Cold-Water Corals. Distribution of fauna and ... - Jacobs University

Cold-Water Corals. Distribution of fauna and responses to 

environmental perturbation 

by 

Autun Purser 

A thesis submitted in partial fulfilment of the requirements for the doctorial degree of 

Date of Defense: 10 th May 2010 

School of Engineering and Science 

Doctor of Philosophy 

in Geosciences 

Approved, thesis committee: 

Prof. Dr. Laurenz Thomsen 

Jacobs University, Germany 

Name and title of chair 

Prof. Dr. Jelle Bijma 

Alfred Wegener Institute, Germany 


Name and title of committee member 

Prof. Dr. Vikram Unnithan 


Name and title of committee member 

Dr. Andres Rüggeberg 

University of Ghent, Belgium 

Name and title of committee member

Cold-Water Corals. Distribution of fauna and responses 

to environmental perturbation 

by 

Autun Purser 

A thesis submitted in partial fulfilment of the requirements for the doctorial degree of 

Doctor of Philosophy 

in Geosciences 

Autun Purser 09

Frontispiece: Brisingid sea stars (Novodinia semicoronata) utilising coral structure to 

attain height from the substrate, presumably with the purpose of 

increasing particle flux to the fan arranged arms:

Abstract 

Over the last decade, the importance of Cold-Water Coral (CWC) reefs as hotspots of 

elevated biodiversity on the European continental margin has become firmly established in 

scientific literature. Reefs are formed predominantly by the calcium carbonate skeletons of 

successive generations of Scleractinian corals such as Lophelia pertusa (Linnaeus, 1758). 

This skeletal structure often forms complex 3D structures which can provide a host of habitat 

niches for other fauna. Advances in remote sensing techniques has led to the location of a 

large number of reef structures, commonly in regions with elevated flow or productivity, such 

as on the Norwegian margin. Often these reefs are associated with high commercial fish 

stocks, and structural damage to reef ecosystems from fishing activity has led to 

progressively more CWC reefs being closed to fishing by various national legislations. The 

oil and gas industry also operates in regions and at depths where extensive reef structures 

can are found, and there is a level of concern over the potential negative impact this industry 

may have on these ecosystems. 

The variation in faunal composition across and between reefs has only been investigated in 

a few studies to date. Likewise, the fundamental functioning of some of the key ecosystem 

species, such as Lophelia pertusa, is not well understood. In this thesis a selection of 

techniques were used to fill some of these knowledge gaps. 

A novel method was developed utilising machine-learning algorithms to swiftly and semiautomatically 

quantify percentage coverage of substrate by living coral polyps. The system 

was used to assess live coral coverage across a trawl damaged region of the Tisler reef, 

Norway. The machine-learning algorithm method performed as accurately as a human in 

quantifying coverage (using standard methodologies), but in considerably less time. 

Distribution of a selection of fauna across and between Norwegian reefs was investigated 

using a large dataset collected as part of the Hotspot Research on the Margin of European 

Seas (HERMES) project. Previously unreported distribution patterns were observed on a 

variety of spatial scales for a number of the species investigated. 

Laboratory work was conducted to determine the degree to which flow velocity related to net 

zooplankton capture rates by Lophelia pertusa. The investigation clearly indicated that a 

significantly higher capture rate was attainable under 0.025 m s -1 than 0.05 m s -1 flow 

velocity, a surprising result given the high flow velocities often prevalent at reef locations. 

Additional laboratory investigations subjecting Lophelia pertusa polyps to doses of various 

anthropogenic materials (waste from drilling operations, trawl resuspended sediments) were 

conducted, with results indicating a general resilience of the species to particle exposure.

List of publications 

Papers presented in the context of this thesis: 

Purser A, Bergmann M, Lundälv T, Ontrup J, Nattkemper TW (2009). Use of machinelearning 

algorithms for the automated detection of cold-water coral habitats: a pilot study. 

Published: Marine Ecology Progress Series 397: 241-251. 

Purser A, Orejas C, Gori A, Thomsen L, Tong R, Unnithan V. Local and regional distribution 

of cold-water coral reef species on the Norwegian margin. 

In preparation. 

Purser A, Larsson AI, Thomsen L, Van Oevelen D. An experimental assessment of the 

influence of flow velocity and food concentration on Lophelia pertusa (Scleractinia) 

zooplankton capture rates. 

Submitted to The Journal of Experimental Marine Biology and Ecology, February 2010. 

Purser A, Larsson AI, Thomsen L. Change in polyp behaviour of the cold-water coral 

Lophelia pertusa (Scleractinia) following exposure to drill cuttings or resuspended 

sediments. 

In preparation. 

Papers completed as co-author during PhD studies, but not presented within the context of 

this thesis: 

Wagner H, Purser A, Thomsen L, Jesus CC, Lundälv T. Particulate organic matter fluxes 

and hydrodynamics at the Tisler Cold-Water Coral Reef. 

Submitted to the Journal of Marine Systems, February 2010. 

Allers E, Abed RMM, Wehrmann LM, Wang T, Larsson AI, Purser A, de Beer D. Effects of 

sedimentation load and sediment type on the cold-water coral Lophelia pertusa. 

Under revision.

Oral presentations: 

List of presentations 

1. "The impact of increased suspended particle load on the scleractinian coral Lophelia 

pertusa." - Purser A, Larsson AI, Thomsen L. 

43rd European Marine Biology Symposium, University of the Azores, Portugal. 8- 

12th Sept 2008. 

2. "The applicability of machine-learning algorithms for the automated detection and 

classification of cold-water coral habitats from video transect data." - Purser A, 

Bergmann M, Lundälv T, Nattkemper TW, Ontrup J. 

4th ISDSC Deepsea Coral Symposium, NIWA, New Zealand. 1-5th Dec 2008. 

3. "The applicability of machine-learning algorithms for the automated detection and 

classification of cold-water coral and sponge habitats from video transect data." - 

Purser A, Bergmann M, Lundälv T, Nattkemper TW, Ontrup J. 

HERMES final meeting, Faro, Portugal. 2-6th March 2009. 

4. "Insights from the Coral Risk Assessment, Modelling and Monitoring (CORAMM) 

project: Cold-water coral reefs and anthropogenic drilling waste." - Purser A, 

Thomsen L, Abed R, Allers E, Bergmann M, de Beer D, Johnsen S, de Laender F, 

Larsson AI, Lundälv T, Nattkemper TW, Nilssen I, Van Oevelen D, Ontrup J, Rønning 

I, Smit M, Unnithan V, Wagner H, Wang T. 

HERMIONE - Anthropogenic impacts workshop, CSIC, Spain. 20-21st Oct 2009. 

Posters prepared and presented: 

1. "The aggregation and deposition of 'drill cuttings' in Norwegian waters, and the 

potential for impact on Cold Water Coral reefs." - Purser A, Thomsen L, Lundälv T. 

2rd HERMES meeting, Faro, Portugal. March 2007. 

2. "Local variation in oxygen concentration across cold-water coral reefs." - Purser A, 

Thomsen L. 

3rd HERMES meeting, Faro, Portugal. March 2008.

3. "The CORAMM (Coral Risk Assessment, Monitoring and Modelling) Project" - 

Purser A, Thomsen L, Abed R, Allers E, Bergmann M, de Beer D, Johnsen S, de 

Laender F, Larsson AI, Lundälv T, Nattkemper TW, Nilssen I, Van Oevelen D, Ontrup 

J, Rønning I, Smit M, Unnithan V, Wagner H, Wang T. 

4th ISDSC Deepsea Coral Symposium, NIWA, New Zealand. 1-5th Dec 2008. 

Revised version additionally presented at Geohab 2009, Trondheim, Norway, May 

2009 by Bergmann M. 

Posters prepared: 

4. "HERMES developing technologies: Automated analysis of marine images." - Purser 

A, Thomsen L, Unnithan V, Bergmann M, Lundälv T, Ontrup J, Nattkemper TW. 

HERMES Science policy meeting, Brussels, May 2009. Presented by Sybille van den 

Hove. 

Revised version additionally presented at Geohab 2009. 

Cruise participation 

ARK XXII / 1a FS Polarstern. 

Norwegian margin HERMES cruise, Germany – Norway, May - June 

2007. 

CE0915 RV Celtic Explorer. 

Geogenic reefs in Irish waters. Marine Institute, Ireland, October 2009.

Abstract 

Publications 

Presentations 

Cruise Participation 

Contents 

Figures 

Tables 

Contents 

Chapter 1 – Introduction 1 

1.0 Introduction 2 

1.1 PhD study within the HERMES and CORAMM projects 2 

1.1.1 The HERMES project 2 

1.1.2 The CORAMM project 3 

1.1.3 Aims of PhD research 5 

1.2 Cold-Water Corals 7 

1.2.1 Scleractinia 8 

1.2.2 Octocorallia 11 

1.2.3 Stylasteridae, Antipatharia and Zoanthidae 13 

1.3 Other reef species 14 

1.4 Reef morphologies 14 

1.5 Cold-Water Coral reefs on the Norwegian margin 16 

1.5.1 Exploration and mapping 16 

1.6 Anthropogenic threats 17 

1.6.1 Fishing 17 

1.6.2 Oil and Gas industry 17 

1.6.3 Rubbish 21 

1.6.4 Climate change 21 

1.7 References 21 

Chapter 2 - Paper 1 25 

"Use of machine-learning algorithms for the automated detection 

of cold-water coral habitats: a pilot study" 

Abstract 26 

Introduction 26 

Materials and methods 27 

Results 31 

Lophelia pertusa coverage estimations 31 

Sponge coverage estimations 32 

Assessment effort 32 

Discussion 32 

Auto analysis approach: Strengths and weaknesses 32 

Applicability for reef mapping 34 

Applicability for management and monitoring 35 

Acknowledgements 35 

Literature cited 35


"Local and regional distribution of cold-water coral reef species on the 

Norwegian margin" 

Abstract 38 

Introduction 38 

Methodology 41 

Survey sites 41 

Video sampling 43 

Substrate categories and investigated species 43 

Statistical study 47 

Results 49 

Species density variation 49 

Lophelia pertusa 55 

Madrepora oculata 56 

Primnoa resedaeformis 57 

Paragorgia arborea 57 

Fish 60 

Mycale lingua 60 

Geodia baretti 61 

Acesta excavata 61 

Anthropogenic material 61 

Discussion 62 

General reef morphology 62 

Species distributions 62 

Anthropogenic impacts 65 

Conclusions 65 


References 66 


"An experimental assessment of the influence of flow velocity and food 

concentration on Lophelia pertusa (Scleractinia) zooplankton capture rates" 

Abstract 71 

1 Introduction 71 

2 Materials and Methods 73 

2.1 Sample site and sampling technique 73 

2.2 Lophelia pertusa preparation 74 

2.3 Flume setup 75 

2.4 Food characterisation 76 

2.5 Experimental runs 76 

2.6 Control runs 78 

2.7 Statistics 78 

3 Results 78 

3.1 C and N concentration or Artemia salina nauplii 78 

3.2 Maximum capture rate 79 

3.3 Artemia salina removal over 24 hrs 80 

4 Discussion 82 

4.1 Flow speed and capture rates 82 

4.2 Food concentration and capture rates 84 

4.3 Polyp size and net capture rate 85 

4.4 Carbon capture 85 

4.5 Outlook 86

5 Conclusion 86 


References 86 


"Change in polyp behaviour of the cold-water coral Lophelia pertusa 

(Scleractinia) following exposure to drill cuttings or resuspended sediments" 

Abstract 93 

1 Introduction 94 

2 Materials and Methods 96 

2.1 Lophelia pertusa polyp collection and preparation 96 

2.2 Drill cutting and local sediment preparation 97 

2.3 Experimental methodology 98 

2.4 Percentage surface clearance 100 

2.5 Statistical analysis 100 

3 Results 101 

3.1 Percentage surface clearance 101 

3.2 Polyp activity 101 

4 Discussion 107 

4.1 Particle clearance rates 107 

4.2 Polyp Behaviour following exposure 107 

4.3 Recommendations 108 


References 110 

Chapter6 - Summary and Future plans 114 

Summary 115 

Future plans 117 


Appendix 119 

Appendix 1 – Small scale flow conditions around reef structures 119 

Appendix 2 – Size variation with depth of drill cuttings from the ‘Nona’ Well 121

Chapter 1 – Introduction 

Figures 

Figure 1. Large rear face of living Røst reef Lophelia pertusa bank. 9 

Figure 2. Typically species rich section of structural cold-water coral substrate. 15 

Figure 3. Typical drill cutting material from a 17.5” well hole section. 19 

Figure 4. Two size distribution profiles of

Figure 8. MDS plots of fourth root transformed abundance data from each 55 

of the JAGO dives. 

Figure 9. Lophelia pertusa polyp coverage of structure substrate at 56 

each reef. 

Figure 10. Average Paragorgia arborea size variation observed at Røst, 59 

Sotbakken and Traena reefs. 

Figure 11. Average Paragorgia arborea colony colour variation observed 59 

at Røst, Sotbakken and Traena reefs. 

Chapter 4 - Paper 3 



Figure 1. Scale diagram of re-circulating flume setup. 75 

Figure 2. Artemia salina concentration over time in flume B during 4 81 

experimental runs with initial concentration of 1030 A. salina l -1 . 

Figure 3. Artemia salina concentration over time in flume C .3 experimental 81 

runs are shown, with 345, 690 and 1035 A. salina l -1 initial 

concentrations. 

Figure 4. Artemia salina concentration over time under 0.025 m s -1 flow in 83 

flume A. 




Figure 1. Size distribution of particles used in coral exposures. 98 

Figure 2. The three classifications of polyp activity used in this study. 99 

Figure 3. Percentage of polyp activity found across the three replicate 105 

aquaria for the three local sediment exposure concentrations. 

Figure 4. Percentage of polyp activity found across the three replicate 106 

aquaria for the three drill cutting exposure concentrations.


Tables 

"Use of machine-learning algorithms for the automated detection 

of cold-water coral habitats: a pilot study" 

Table 1. Results of cross-correlation comparisons between the various 31 

tested methodologies in identification of Lophelia pertusa and 

the sponges Geodia baretti and Mycale lingua. 

Table 2. Mean time spent analysing each video frame with the different 32 

methodologies. 




Table 1. Date, location, depth and length of each survey transect. 42 

Table 2. Species densities observed on each substrate type throughout 50 

each of the survey dives. 

Table 3. Morisita’s index scores for each species and substrate type. All 58 

regions of uniform substrate (>20m length) were analysed. 




Table 1. Table showing the number of live Lophelia pertusa polyps, the 77 

average polyp diameters and buoyant weights of all branches 

used in each of the experimental flumes. 

Table 2. Table showing maximum rates of Artemia salina removal 79 

from suspension within each flume during the initial 6 hrs 

of each experimental run. 




Table 1. Depth, latitude and longitude of Lophelia pertusa coral blocks. 96 

Table 2. Percentage clearance ability of 29 Lophelia pertusa fragments 103 

exposed to local sediments. 

Table 3. Percentage clearance ability of 30 Lophelia pertusa fragments 104 

exposed to drill cuttings.

Chapter 1 

Introduction 

1

1.0 Introduction 

Cold-Water Coral (CWC) ecosystems are amongst the most biologically diverse and 

commercially significant habitats on the European continental margin (Roberts et al, 2009). 

They are formed predominantly by the accumulation over time of biogenic calcium carbonate 

skeletal material secreted by azooxanthellate coral animals with growth. This skeletal 

material forms a complex, three-dimensional structure which provides habitat niches for a 

host of other organisms. Over the last two decades improvements in remote sensing 

technology and international collaborative research projects such as HERMES, HERMIONE 

and CORAMM have allowed these often remote ecosystems to be studied quantitatively. 

The papers and findings presented in this thesis were produced during my PhD studies as a 

graduate student within the HERMES and CORAMM research projects. In this chapter I will 

present the aims of my PhD research within the framework of these two projects and 

introduce to the interested reader some of the fauna, history and distribution of CWC reefs 

on the Norwegian margin. 

1.1 PhD study within the HERMES and CORAMM projects 

My PhD studies were conducted as a graduate student within the recently completed 

HERMES and CORAMM research projects, and as such were partially directed by the goals 

of these projects. 

1.1.1 The HERMES project 

The Hotspot Ecosystems Research on the Margins of European Seas (HERMES) was a 

particularly successful project funded by the European Commission's Sixth Framework 

Programme. The project ran from April 2005 to March 2009 and was aimed at combining 

together a number of partner organisations in (primarily biological) research at a selection of 

the more biodiverse regions of the European seafloor. By project close, 50 partner 

organizations from 17 nations had taken part in the research. The project was structured 

around 10 interrelated workpackages, five of which dealt with study of varying ecosystems, 

with a further five covering cross-cutting issues such as data management and education 

and outreach (this particular workpackage was co-ordinated by Jacobs University, Bremen). 

Workpackage 2 dealt with cold-water corals and carbonate mound systems. The results from 

2

investigations into reef formation, growth histories, distribution and faunal composition 

produced by this workpackage have been published widely, with new HERMES papers still 

coming to press periodically. 

1.1.2 The CORAMM project 

The Coral Risk Assessment, Monitoring and Modelling (CORAMM) project was a ~3 year 

initiative co-ordinated by Jacobs University, Bremen and funded by Statoil, Norway. The 

project brought together 7 principal partners in trying to develop a novel approach to 

investigating seafloor cold-water coral ecosystems. CORAMM partners were:- 

Jacobs University, Bremen, Germany 

Alfred Wegener Institute for Marine and Polar Research (AWI), Germany 

Gothenburg University, Sweden 

The Max Plank Institute for Marine Microbiology (MPI) 

The Netherlands Institute for Ecology (NIOO) 

Bielefeld University, Germany 

Statoil, Norway 

Additional project support: 

Partners from the International Consortium on Continental Margins (IRCCM) and 

HERMES were involved in some of the research and infrastructure support. 

Institute of Marine Research (IMR), Norway, gave permission for sampling of 

Lophelia pertusa from the protected Tisler Reef, Norway for use in experimental 

studies. 

From the outset the intention of the CORAMM project was to produce a cohesive results 

dataset which would both increase general understanding of these dynamic ecosystems, 

and also feed as directly into future ecosystem management strategies. CORAMM 

attempted to fill a number of the many gaps in knowledge about how best to assess and 

monitor reef health, and the degree to which key ecosystem species are impacted by 

exposure to anthropogenically produced particulate material. A primary aim of CORAMM 

was to investigate whether or not exposure to 'drill cuttings', (waste products from drilling 

operations, section 1.6.2) would have a negative impact on coral health. CORAMM 

consisted of four workpackages:- 

3

Workpackage 1 

This workpackage concentrated on developing new image analysis techniques to allow swift, 

accurate assessment of cold-water coral reef condition from video survey data. As is 

discussed further in section 1.6.1, at time of writing a number of reefs have been and 

continue to be damaged by fishing action. A rapid quantification of reef condition and the 

improvement of monitoring strategies could benefit from developments in video image 

analysis. Two such developments focused on within the framework of the CORAMM project 

were video mosaicing and automated image analysis. In videomosaicing, video data 

collected by submarine, remove operated vehicle (ROV) or by towed camera sled is semiautomatically 

arranged within a computer to produce a larger composite image or seabed 

map. The second CORAMM focus was on developing automated methods to allow a 

computer to 'learn' how to recognise fauna species or reef health status directly from video 

data. 

Workpackage 2 

This workpackage focused on getting accurate, time series data on nutrient supply, particle 

size, particle flux, temperature, flow speed and flow direction data from within and around 

the Tisler cold-water coral reef, Norwegian Skagerrak. The reason for doing so was to try 

and assess the maximum, minimum and average levels of these parameters a particular reef 

experiences. Snapshot readings from a selection of reefs recorded during research cruises 

have been made at a number of sites (Kiriakoulakis et al, 2005; Kiriakoulakis et al, 2007; 

Davies et al, 2009), but time series data was still rather lacking at commencement of the 

CORAMM project, although some nutrient and flow velocity studies have recently been 

published (Lavaleye et al, 2009). Such data is useful for helping locate other reefs using 

niche factor analysis (Davies et al, 2008 ) in constructing dynamic energy budget models of 

reefs and to aid in determining what volume of material held in suspension within benthic 

boundary layers of the ocean may reach and interact with reef ecosystems. 

Workpackage 3 

Workpackage 3 consisted of a number of experimental investigations aimed at addressing 

some of the gaps in knowledge of Lophelia pertusa feeding, reproduction, respiration, 

susceptibility to particle exposure and growth. 

4

Workpackage 4 

This workpackage aimed to take the results from the other workpackages and use them in 

developing a Dynamic Energy Budget (DEB) model of a healthy CWC reef. The completed 

model will be incorporated into the Environmental Risk Assessment (ERA) strategy utilised 

by Statoil, with the aim of further minimising potential risks to the benthic environment posed 

by company activities. Within the CORAMM project architecture, the modellers played a 

major role in all stages of experimental work, helping to ensure results were produced in the 

laboratory or field in such a way as to be suitable for direct inclusion into their models. Such 

an early involvement with the modellers was a novel and very successful approach, with a 

host of papers currently submitted or in preparation produced from the collaborative results. 

1.1.3 Aims of PhD research 

Prior to my PhD studies I studied for a very interdisciplinary 'MSc Oceanography' 

qualification at the National Oceanography Centre, Southampton, UK. As one of the few 

PhD students involved in the CORAMM project there was a great opportunity to carry out 

further interdisciplinary studies. The start of my PhD coincided with the start of the CORAMM 

project and so my initial research aims were focused on the fundamental early requirements 

of that project. 

Drill cuttings 

As mentioned in 1.1.2, the CORAMM project was particularly interested in assessing 

whether or not exposure to drill cuttings could a negative impact on CWC organisms and 

ecosystems. Such a question is difficult to address wholly in the lifetime of a three year 

project, made doubly difficult considering the variety in composition and particle size 

distribution of drill cuttings discharged to sea (see 1.6.2). An early focus of my research work 

was to try and address these issues. 

Within the lifetime of the CORAMM project Statoil delivered ~100 different drill cutting 

samples from 4 drilling operations. I was the principal investigator assessing the particle size 

composition and settling rates of these samples. These parameters are of critical importance 

when attempting to determine transport of the material following release to the ocean. 

5

Analysis showed that between 25 and 75% of the drill cuttings (by dry weight) could be of 

and gas industry, where environmental assessments prior and post activity are required, 

developments to improve such monitoring strategies are of interest. As part of my thesis I 

worked with CORAMM partners on developing a system to automatically assess the seabed 

coverage of a selection of organisms of interest when assessing reef health. By marking on 

a number of still video images taken from a standard ROV monitoring video collected from 

the Tisler reef, Norway, a computer algorithm was used to 'teach' the computer to recognise 

the fauna in other images. The technique proved to be very time effective and accurate in 

assessing Lophelia pertusa seabed coverage, the monitoring of which is of crucial concern 

in CWC management plans for CWC reefs on the Norwegian margin. The first paper 

produced from this fruitful strand of CORAMM work forms chapter 2 of this thesis. 

Cold-water coral faunal homogeneity across the Norwegian margin 

As a HERMES PhD student I had the opportunity to take part in a cruise to three reefs on 

the Norwegian margin. ~36 hours of video transect data was collected from these reefs by 

submarine. From these video data I quantified distributions of a selection of key reef species 

spatially. Although presence / absence data for a number of species is reasonably well 

known across and between some Norwegian reefs there had previously been little work 

done in assessing relative densities. My aim in carrying out this work was two-fold. Firstly, to 

see whether there were any major patterns in distribution, and secondly, to determine 

whether reefs were likely to be reasonably similar in total faunal composition or quite distinct. 

This work fed into HERMES workpackage 2 and quantifies distributions of a selection of 

species for the first time. The results from this investigation form chapter 3. 

1.2 Cold-Water Corals 

Cold-Water Corals are unfortunately not wholly easy to define, with the term applied broadly 

to cover species from a selection of orders and classes within the phylum Cnidaria. These 

species can inhabit, but do not exclusively do so, waters colder than those associated with 

tropical or warm water corals. One of the most significant differences between cold and 

warm water corals is that cold-water corals never live in association with algal symbionts, as 

is commonly the case with tropical corals (Rogers, 1999; Roberts et al, 2006) – cold-water 

corals are exclusively azooxanthellate. This lack of an algal associate means the coral 

animal must collect its energy directly from food or dissolved organic matter, with no ‘on tap’ 

supply to be received as required from an algal symbiont. This difference has led to the 

7

commonly observed slower growth rates in cold-water corals, and the freeing up of the 

aphotic zone for coral colonisation. Depth ranges of many species can be measured in the 

1000s of meters, (Freiwald et al, 2004), although in European waters the majority of coral 

biomass is found at depths associated with the continental margin and shelf (Del Mol et al, 

2002; Dorschel et al, 2005; Huvenne et al, 2007). 

A percentage of CWC species are habitat engineers. With growth they develop a structure 

which can provide habitat niches for other organisms. Such niches can be structural, 

providing suitable substrate for sessile organisms (Henry, 2001; Jensen and Frederiksen et 

al, 1992), for small mobile arthropods (Buhl-Mortensen and Mortensen, 2004), or refuges for 

fish (Kreiger and Wing, 2002). Growth can also alter the local hydrodynamic conditions, 

providing regions of increased and reduced flow (Dorschel et al, 2005; White, 2007), again 

adding complexity to the seafloor environment. Certain species of these habitat engineer 

CWC’s can over time, given favourable environmental conditions and nutrient supply, 

produce colonies of kilometres in length and tens of meters in height (Fosså et al, 2002; 

Freiwald et al, 2002), with the vigour of reef growth often changing with environmental 

perturbation, such as associated with glaciation events (Rüggeberg et al, 2007). 

Habitat engineer CWC species are predominantly from five of the cnidarian taxa, each of 

which will be introduced briefly here. The interested reader is forwarded to the recent book 

by Roberts et al, (2009), for a more detailed overview. 

1.2.1. Scleractinia 

Of the 711 known species of scleractinian corals, all but 89 are azooxanthellate and capable 

of growth at depths where light penetration is not sufficient for photosynthesis. These corals 

are the predominant hard, rocky members of both tropical and cold-water coral reefs. 

Species can be colonial or solitary in growth, with the colonial species being the most 

significant in the development of large reef structures. Individual coral polyps in these 

colonies tend to bud off from the parent (sexual and asexual reproduction a possibility with 

most species) and grow near vertically from them, forming a hard calcium carbonate (in the 

aragonite form) skeleton with growth. The reef structure is built up by progressive 

generations of live polyps growing on the skeletal structure deposited by previous 

generations (figure 1). Commonly, live corals meet and calcify together, adding additional 

rigidity to the reef structure. In European waters, the major species are Lophelia pertusa, 

Madrepora oculata and perhaps Solensomilia variabilis. At individual tropical coral reefs a 

8

selection of scleractinian species are often represented, whereas at CWC reefs structure is 

generally produced by one species. Populations of a second and/or third species can be 

present at a CWC reef, but are usually in much lower abundance. 

SCALE photograph height ~1.5m Photo: A Purser from JAGO submersible (IFM-GEOMAR) 

Figure 1. Large rear face of living Røst reef Lophelia pertusa bank. Note thin fringe of living polyps at the top of 

the photograph. 

Lophelia pertusa 

Lophelia pertusa is the primary framework building coral at the majority of European CWC 

reefs (Roberts et al, 2009). Initial reef development is likely only possible if a sufficiently 

large region of an appropriate hard substrate is available for settlement. Small patches of 

Lophelia pertusa growth can also be found on isolated drop stones or on substrates of 

anthropogenic origin (shipwrecks, oil rigs etc.), and given time, even these small growths 

can potentially develop into large reef structures, with dead skeletal material falling from the 

small colonies to produce an ever expanding area of suitable hard substrate for settlement 

and growth. 

9

The majority of the living biomass is within the ~1cm diameter calcium carbonate cups, but a 

living, very thin coenosarc covers the exterior of the coral skeleton, often running in an 

unbroken sheet from one living polyp to its adjacent neighbours. Each individual polyp 

probably lives

comparable area of seabed, there is a strong likelihood that there is a reef affect still in 

evidence, particularly downstream of the reef in regions with prevailing current directions. 

Recent studies have shown that the mucus from cold-water coral reefs can be readily 

suspended or dissolved, and carried in such a fashion a considerable distance from point of 

release by the reef (Wild et al, 2008), thus influencing nutrient supply to these surrounding 

seafloor regions. 

Madrepora oculata 

Similar in distribution and appearance to Lophelia pertusa, this species is distinguished from 

L. pertusa by having generally smaller polyp diameters (

individual polyps gathered together onto the various branches of the octocoral ‘tree’. There is 

great variety in growth form and lifestyle found across species, and there are many 

unknowns regarding feeding behaviour, growth rates and distribution strategies of even the 

most common species. 

With growth, Octocorals can provide substrates and habitat niches for other organisms, 

sometimes with a single colony hosting dozens of associate species (Mortensen and Buhl- 

Mortensen, 2004). Fish commonly take advantage of the cover provided by the octocoral 

branches, or the variation in benthic current flow resulting from colony morphology (Krieger, 

1993, Krieger and Wing, 2002). Octocorals are not (in the majority of species) as rigid as 

scleractinians, and although they tend to have a central, firm axis, a degree of flexibility is 

provided by not fusing the components of this axis (Roberts et al, 2009). 

Commonly at CWC reefs in European waters, octocorals add additional habitat complexity to 

that provided by the more substantial underlying reef structure built up by scleractinian 

growth. Two species, Paragorgia arborea and Primnoa resedaeformis, are two of the most 

significant octocorals within European reef environments. 

Paragorgia arborea (Linnaeus, 1758) 

Often the most colourful member of European CWC reef communities, Paragorgia arborea 

can form bright pink, salmon or white tree-like structures with growth (Mortensen and Buhl- 

Mortensen, 2005). Commonly they are referred to as ‘bubblegum’ corals, because of the 

distinct lumpy morphology of the colony branches. Their association with scleractinian CWC 

reefs has been noted on both sides of the Atlantic, and colonies are additionally found away 

from reef structures, on the continental margin and slope, down to considerable depths (). 

Substrate is a limiting factor in maximum colony growth size in many cases, with larger 

colonies falling over under high flow conditions if rooted to partially mobile substrates, such 

as stones. 

Growth of colonies is often near vertical, into the prevailing currents and into the 

progressively less turbid waters found above the substrate (Warner, 1977). A consequence 

of this morphology, however, is an increased susceptibility to the majority of fishing 

techniques that can be employed at reef locations, such as trawling and long-line fishing. 

Paragorgia arborea is a commonly reported bycatch in fishing areas where it is distributed. 

Attempts to gauge the speed of colony growth have been frustratingly unsuccessful to date 

12

(Mortensen and Buhl-Mortensen, 2005), but a relatively slow growth rate of just a few mm a 

year is likely. As with other slow growing deep sea organisms, populations can rapidly 

decline if stocks not given a chance to recover following fishing or anthropogenic 

perturbation of the seafloor. 

Primnoa resedaeformis (Gunnerus, 1763) 

Often found in close association with Paragorgia arborea, Primnoa resedaeformis again 

forms a branched, tree-like structure with growth, but one of considerably less rigidity. 

Branches are often draped on or close to the substrate, and seldom stand high into the 

prevailing current. It is hypothesised that the coral can utilise a more refractory food source 

than P. arborea, such as can be delivered in the form of resuspended material in the bottom 

currents. 

Some success has been made in gauging growth of Primnoa resedaeformis colonies, and 

for much of the colony lifespan, longitudinal extension of branches is measured in a few mm 

yr -1 (Mortensen and Buhl-Mortensen, 2005). Despite colony growth form being more closely 

aligned with the seabed than Paragorgia arborea, colonies are also often reported as fishing 

bycatch (Mortensen et al, 2005). 

1.2.3. Stylasteridae, Antipatharia and Zoanthidae 

Stylasterids are colonial, calcium carbonate secreting colonial corals (in both aragonite and 

calcite forms, depending on species). Although much like scleractinians in composition and 

rigidity, they often appear more similar to octocorals in growth morphology, forming a 

branched, tree-like structures with growth. They are not spatially significant structural 

components of the reefs on much of the European margin, although they are present in low 

abundances at many reef sites. 

Antipatharians, or black corals, can form branched tree-like colonies or whip like forms with 

growth, and some individuals seem to live for in excess of 2000 years. They are common at 

great depth, and are often host to a selection of associate fauna. As with Stylasteridae, they 

seem variable in their association with scleractinian reefs on the European margin. During 

my research cruises carried out within the timeframe of this PhD I saw a selection of species 

13

on the Irish margin, but very few at comparable reef locations on the Norwegian margin. 

They are not discussed at length in this thesis. 

Zoanthidae, soft bodied colonial animals for the most part have only a few harder-bodied 

species providing habitat niches for other species. With these hard bodied species rare in 

European waters, this taxa is not discussed further within this thesis. 

1.3 Other reef species 

Cold-water coral reef communities often consist of representatives from a great range of 

families and species (figure 2, Roberts et al, 2008). Very few, if any, species are endemic to 

reef structures. Reefs tend to be high density foci of species occurring under comparable 

oceanographic conditions in the general region. This localisation of so many species into a 

comparatively small area is the cause of the regional high biodiversity reported from reef 

sites by alpha- and beta- diversity investigations (Henry and Roberts, 2007). Fish densities 

are often observed to be higher in the vicinity of reef structures than on adjacent areas of the 

seabed (Costello et al, 2005). 

1.4 Reef morphologies 

Underlying substrate and seabed relief are predominant factors determining reef morphology 

at many locations. Following considerable periods of reef growth, development can overwrite 

the initial reef morphology as successive generations of polyps generate increasing volumes 

of calcium carbonate skeletal structure. Sediment baffling within this dead material can lead 

to large mound development (Dorschel et al, 2005). Oceanic flow conditions as well as 

depositional rates can also determine overall reef morphology, as can nutrient supply (Fosså 

et al, 2005). 

14

Scale x 0.5 A. Purser 09 

Figure 2. Typically species rich section of structural cold-water coral substrate on the border of the coral rubble 

region. In the illustration some clumps of living Lophelia pertusa overgrow an area of eroded dead coral 

substrate. A number of sessile species (several sponges, two ascidians, anemones, damaged antipatharian coral 

colonies) also utilise the hard substrate. Mobile ophiuroids and Pandalus sp. also utilise habitat niches. 

15

1.5 Cold-Water Coral reefs on the Norwegian margin 

The scientific study of cold-water corals originated in the 18th century in Norway with the first 

documented findings of Lophelia pertusa being made in Norwegian waters (Linneaus, 1758). 

Over the last 250 years the country has led CWC research, with the extensive reefs in the 

countries waters the most comprehensively documented worldwide, even so, large reef 

structures are still likely to be located and the great majority of relationships between species 

and environmental conditions have yet to be identified and / or fully understood. 

1.5.1 Exploration and mapping 

Until the closing decade of the 20th century knowledge of the spatial distribution of CWC 

habitats was limited. Although generally deep (>50m depth) a selection of the fjord reefs 

(such as Trondheimfjord, (Broch, 1912)) were the only ones accurately located. Fishermen, 

however, have known the rough locations of many reef structures for many years, having 

caught fragments of coral periodically in equipment employed in nets deployed in the 

generally quite productive reef areas (Fosså et al, 2005; Fosså et al, 2010). 

The concerns of gillnet and longline fishermen over the degrading of reef habitats associated 

with trawl fishing in the late 1990s prompted the IMR, Norway to commence the first largescale 

scientific studies of reef areas. From 2000 onward, the IMR employed acoustic 

Multibeam Echo Sounders (MBE) to remotely image the seabed, with online data processing 

systems identifying possible regions of cold-water corals in real-time (with groundtruthing by 

ROV or dropcam). Technology is moving swiftly in this area, and accuracy of seabed 

classification systems is increasing rapidly (Guinan et al, 2009). Generally, however, such 

remote systems can identify only broad seabed habitat types by the acoustic signal (such as 

regions of coral structure, regions of soft sediment). Within this thesis (chapter 2) a novel 

method to semi-automatically classify fauna and substrates from the ROV or dropcam data 

is presented. For an overview of the history and ongoing exploration and mapping strategies 

employed on the Norwegian margin, see Fosså and Skjoldal (2010). 

16

1.6 Anthropogenic threats 

1.6.1 Fishing 

Probably the most significant and immediate anthropogenic threat to CWC habitats is that 

posed by fishing activity. Throughout European waters many of the reefs located have to 

some extent been damaged by fishing. Although historically cold-water coral organisms have 

been a reported bycatch of trawl and longline fishing, developments in fishing equipment 

have placed a progressively higher percentage of the seabed at risk. Development of the 

rockhopper fishing system in the 1980s allowed the trawling of cold-water coral reefs (Fosså 

and Skjoldal, 2010) with the reduced likelihood of damage to fishing equipment. The 

concerns of fishermen over declining reef stocks associated with this development led to the 

investigation and closure of a number of reef sites to bottom trawling in Norwegian waters 

(Fosså et al, 2005; Fosså and Skjoldal, 2010). Throughout European, US and Canadian 

seas nations have begun to protect their CWC reefs similarly (Brock et al, 2009), and 

developments in vessel monitoring systems are helping to ensure compliance with the 

regulations (Hall-Spencer et al, 2009). The majority of protective measures ban bottom 

trawling, which is assumed the most damaging form of fishing to the structure of CWC reefs. 

In many cases, gillnet and longline fishing are not at time of writing banned from these 

regions. Growing evidence shows that these can have significant long-term negative effects 

on gorgonian corals and associate organisms at the least (Krieger, 1993). The International 

Council for the Exploration of the Seas (ICES) recommends a cessation of all bottom-fishing 

techniques in the vicinity of protected reefs. 

A further possible hazard to reefs might be posed by the elevated exposure to resuspended 

material mobilised by trawling in the vicinity of reefs. This resuspension has clearly been 

observed in shallow trawling sites, including regions adjacent to some CWC reefs (T. 

Lündalv, pers. com.). The possible impact on Lophelia pertusa of exposure to such 

resuspended material is unknown. 

1.6.2 Oil and Gas industry 

The Norwegian margin is one of great interest and utilization by the oil and gas industry. 

There are three main areas of concern for CWC habitats related to their operations: 

17

Direct physical disturbance 

Coral reef structures could potentially be damaged by direct physical damage caused by the 

large amount of anchors, pipelines, seabed cables etc. associated with modern exploratory 

and production well drilling. The actual level of risk posed by these activities in Norwegian 

waters is currently low, with the Norwegian Petroleum Activities Act requiring in-depth site 

investigations to be carried out prior to the granting of drilling licences. 

Deposition of waste material 

A secondary concern relates to the release into the ocean of the waste material generated 

by drilling operations, the 'drill cuttings'. As introduced in section 1.1.3 these drill cuttings are 

predominantly the bits of broken up rock strata through which the drill is driven (figure 3). 

There is an additional component consisting of various lubricating chemicals and weighting 

agents (usually barite) used to maintain a positive pressure during drilling and to lubricate 

the process, the 'drilling mud'. For commercial reasons, as much as possible of this drilling 

mud is cleaned from the rock chippings on the drilling rig prior to reuse in the drilling 

process, but a percentage remains stuck to the rock fragments. 

18

SCALE 1:1 A PURSER 

Figure 3. Typical drill cutting material from a 17.5" well hole section. 

These rock chippings consist of various size fractions of material, with the fine fraction likely 

to travel some distance from point of release, possibly aggregating with phytoplankton and 

detritus during surface mixing and sinking. The size distribution of the material is the result of 

a combination of factors, primarily the composition of the rock being drilled and the 

composition of the drilling mud being used. Both of these factors can change quickly within a 

drilling operation, making the drill cuttings delivered to the see relatively inhomogeneous. 

See Appendix 2 for an example of size distribution variation with drilling depth from the 

Heidrun field, Norway. 

The majority of drilling carried out on the Norwegian margin consists of a number of discreet 

stages, characterised to a degree by the diameter of the drill hole. Commonly, the drill hole 

gets progressively narrower in diameter with drill depth. At the seabed surface, a 26" drill is 

commonly employed to drill through the near surface strata. In most cases, these initial rock 

cuttings are left on the seabed and not returned to the drilling platform. As the rock strata get 

more compact with depth, progressively narrower drills are used, with 17.5", 12.25" and 8.5" 

drill diameters used in turn prior to penetration of the reservoir rocks, with drill cutting 

19

material returned to the drill rig for cleaning prior to release. Within European waters, only 

cuttings produced by drill sections bored with water based drilling fluids are released to the 

ocean. Occasionally, and particularly when approaching the reservoir rocks, an oil based 

lubricant is used in the drilling operation, with the drill cuttings produced whilst using such 

lubricants carried to shore for disposal. 

Two examples of drill cutting size distributions are given in figure 4, with further information 

on chemical composition and size variation given in the appendix. 

Figure 4. Two size distribution profiles of the

Pollution events 

The potential impact a pollution event may have on CWC ecosystems is not well known. All 

oil and gas industry production in Norwegian waters is only allowed after submission of 

pollution mitigation and cleanup plans being submitted to the authorities prior to 

commencement of production (Fosså and Skjoldal, 2010). 

1.6.3 Rubbish 

A concern of the HERMIONE project is the increase in plastic marine litter across the deep 

sea ecosystems. The direct effect of such waste on fauna is unclear in many cases. Such 

rubbish has been found in great quantity within Mediterranean coral thickets, and although 

present within Norwegian margin reefs, densities of waste material seem lower and this 

potential hazard to reef health will not be discussed at length within this thesis. 

1.6.4 Climate change 

The major structure forming scleractinian corals found at CWC sites secrete calcium 

carbonate skeletons with growth - they are calcifying organisms. The ability for such 

organisms to produce skeletons in progressively more acidic seas is one of the principal 

concerns over ocean acidification. Additionally, the majority of predictive models expect that 

the oceans of higher latitudes will suffer the most rapid increase in acidity over the 

forthcoming years. This is of prime concern for reefs on the Norwegian margin, some of 

which may be below the aragonite saturation horizon within 100 years. 

1.7 References 

Broch H (1912) Die Alcyonarien des Trondhjemsfjordes II. Gorgonacea. Kgl Norske Vidensk 

Selskabs Skrifter 2: 1-48 

Brock R, English E, Kenchington E, Tasker M (2009) The alphabet soup that protects coldwater 

corals in the North Atlantic. Mar Ecol Prog Ser 397: 355-360 

Buerk L, Freiwald A (2005) Bioerosion patterns in a deep-water Lophelia pertusa 

(Scleractinia) thicket (Propeller Mound, northern Porcupine Seabight). In: Freiwald A, 

Roberts JM (eds) Cold-Water Corals and Ecosystems, Springer, Berlin, p 915-936 

21

Buhl-Mortensen L, Mortensen PB (2004) Crustaceans associated with the deep-water 

gorgonian Paragorgia arborea (L., 1758) and Primnoa resedaeformis (Gunnerus, 1763). J 

Nat His 38: 1233-1247 

Costello M, McCrea M, Freiwald A, Lundälv T, Jonsson L, Bett B, Weering T, Haas H, 

Roberts J, Allen D (2005) Role of cold-water Lophelia pertusa coral reefs as fish habitat in 

the NE Atlantic. In: Freiwald A, Roberts JM (eds) Cold-Water Corals and Ecosystems, 

Springer, Berlin, p 771-805 

Davies AJ, Duineveld GCA, Lavaleye MSS, Bergman MJN, Van Haren H, Roberts J M 

(2009) Downwelling and deep-water bottom currents as food supply mechanisms to the 

cold-water Lophelia pertusa (Scleractinia) at the Mingulay Reef complex. Limnol Oceanogr 

54(2): 620-629 

De Mol B, Van Rensbergen P, Pillen S, Van Herreweghe K, Van Rooij D, McDonnell A, 

Huvenne V, Ivanov M, Swennen R, Henriet JP (2002) Large deep-water coral banks in the 

Porcupine Basin, southwest of Ireland. Mar Geol 188: 193-231 

Dodds LA, Black KD, Orr H, Roberts JM (2009) Lipid biomarkers reveal geographical 

differences in food supply to the cold-water coral Lophelia pertusa (Scleractinia). Mar Ecol 

Prog Ser 397: 113-124 

Dorschel B, Hebbeln D, Rüggeberg A, Dullo WC, Freiwald A (2005) Growth and erosion of a 

cold-water coral covered carbonate mound in the Northeast Atlantic during the Late 

Pleistocene and Holocene. Earth Planet SC Lett 233: 33-44 

Dorschel B, Hebbeln D, Foubert A, White M, Wheeler AJ (2007) Hydrodynamics and coldwater 

coral facies distribution related to recent sedimentary processes at Galway Mound 

west of Ireland. Mar Geol 244: 184-195 

Dullo WC, Flögel S, Rüggeberg A (2008) Cold-water coral growth in relation to the 

hydrography of the Celtic and Nordic European continental margin. Mar Ecol Prog Ser 371: 

165-176 

Fosså JH, Skjoldal HR (2010) Conservation of Cold-Water Coral Reefs in Norway. In: . 

Grafton RQ, Hilborn R, Squires D, Tait M, Williams M (eds) Handbook of Marine Fisheries 

Conservation and Management. Oxford University Press, US. p215-240 

Fosså JH, Lindberg B, Christensen O (2005) Mapping of Lophelia reefs in Norway: 

experiences and survey methods. In: Freiwald A, Roberts JM (eds) Cold-Water Corals and 

Ecosystems, Springer, Berlin, p 359-391 

Fosså JH, Mortensen PB, Furevik DM (2002) The deep-water coral Lophelia pertusa in 

Norwegian waters: distribution and fishery impacts. Hydrobiologia 471: 1-12 


experiences and survey methods. . In: Freiwald A, Roberts JM (eds) Cold-Water Corals and 


Freiwald A, Hühnerbach V, Lindberg B, Wilson JB, Campbell J (2002) The Sula Reef 

complex, Norwegian Shelf. Facies 47: 179-200 

Guinan J, Grehan AJ, Dolan MFJ, Brown C (2009) Quantifying relationships between video 

observations of cold-water coral cover and seafloor features in Rockall Trough, west of 

Ireland. Mar Ecol Prog Ser 375: 125-138 

22

Hall-Spencer JM, Tasker M, Soffker M, Christiansen S, Rogers S, Campbell M, Hoydal K 

(2009) Design of Marine Protected Areas on high seas and territorial waters of Rockall Bank. 

Mar Ecol Prog Ser 397: 305-308 

Henry LA (2001) Hydroids associated with deep-sea corals in the boreal north-west Atlantic. 

J Mar Biol Assoc UK 81: 163-164 

Henry LA, Roberts JM (2007) Biodiversity and ecological composition of macrobenthos on 

cold-water coral mounds and adjacent off-mound habitat in the bathyal Porcupine Seabight, 

NE Atlantic. Deep Sea Res Pt I 54: 654-672 

Huvenne V, Bailey W, Shannon P, Naeth J, di Primio R, Henriet J, Horsfield B, de Haas H, 

Wheeler A, Olu-Le Roy K (2007) The Magellan mound province in the Porcupine Basin. Int J 

Earth Sci 96: 85-101 

Jensen A, Frederiksen R (1992) The fauna associated with the bank-forming deepwater 

coral Lophelia pertusa (Scleractinaria) on the Faroe shelf. Sarsia 77: 53-69 

Kiriakoulakis K, Fisher E, Wolff GA, Freiwald A, Grehan A, Roberts JM (2005) Lipids and 

nitrogen isotopes of two deep-water corals from the North-East Atlantic: initial results and 

implications for their nutrition. In: Freiwald A, Roberts JM (eds) Cold-Water Corals and 


Kiriakoulakis K, Freiwald A, Fisher E, Wolff G (2007) Organic matter quality and supply to 

deep-water coral/mound systems of the NW European Continental Margin. Int J Earth Sci 

96: 159-170 

Krieger KJ (1993) Distribution and abundance of rockfish determined from a submersible 

and by bottom trawling. Fisheries Bulletin 91: 87-96 

Krieger KJ, Wing BL (2002) Megafauna associations with deepwater corals (Primnoa spp.) 

in the Gulf of Alaska. Hydrobiologica 471: 83-90 

Lavaleye M, Duineveld G, Lundälv T, White M, Guihen D, Kiriakoulakis K, Wolff GA (2009) 

Cold-Water corals on the Tisler Reef. Oceanography 22(1): 76-84 

Lepland A, Mortensen P (2008) Barite and barium in sediments and coral skeletons around 

the hydrocarbon exploration drilling site in the Træna Deep, Norwegian Sea. Environ Geol 

56: 119-129 

Mortensen PB, Buhl-Mortensen L (2005) Morphology and growth of the deep-water 

gorgonians Primnoa resedaeformis and Paragorgia arborea. Mar Biol 147: 775-788 

Mortensen PB, Buhl-Mortensen L, Gordon DC (2005) Effects of fisheries on deepwater 

gorgonian corals in the Northeast Channel, Nova Scotia. In: Barnes PW, Thomas JP (eds) 

Benthic Habitats and the Effects of Fishing. American Fisheries Society Symposium 41: 369- 

382 

Orejas C, Gori A, Lo lacono C, Puig P, Gili JM, Dale MRT (2009) Cold-water corals in the 

Cap de Creus canyon, northwestern Mediterranean: spatial distribution, density and 

anthropogenic impact. Mar Ecol Prog Ser 397: 37-51 

Roberts JM, Wheeler AJ, Freiwald A (2006) Reefs of the Deep: The Biology and Geology of 

Cold-Water Coral Ecosystems. Science 312: 543-547 

23

Roberts J, Henry LA, Long D, Hartley J (2008) Cold-water coral reef frameworks, 

megafaunal communities and evidence for coral carbonate mounds on the Hatton Bank, 

north east Atlantic. Facies 54: 297-316 

Roberts JM, Wheeler A, Freiwald A, Cairns S (2009) Cold-Water Corals. The Biology and 

Geology of Deep-Sea Coral Habitats. Cambridge, UK 

Rogers AD (1999) The biology of Lophelia pertusa (LINNAEUS 1758) and other deep-water 

reef-forming corals and impacts from human activities. Int Rev Hydrobiol 84: 315-406 

Rüggeberg A, Dullo C, Dorschel B, Hebbelm D (2007) Environmental changes and growth 

history of a cold-water carbonate mound (Propeller Mound, Porcupine Seabight). Int J Earth 

Sci 96: 57-72 

Waller RG, Tyler PA (2005) The reproductive biology of two deep-water, reef-building 

scleractinians from the NE Atlantic Ocean. Coral Reefs 24: 514-522 

Warner GF (1977) On the shapes of passive suspension feeders. In: Keegan BF, Ceidigh 

PO, Boaden PJS (eds) Biology of benthic organisms, Pergamon, Oxford, p 567-576 

White M (2007) Benthic dynamics at the carbonate mound regions of the Porcupine Sea 

Bight continental margin. Int J Earth Sci 96: 1-9 

Wild C, Mayr C, Wehrmann L, Schöttner S, Naumann M, Hoffmann F, Rapp HT (2008) 

Organic matter release by cold-water corals and its implication for fauna-microbe interaction. 


24

Chapter 2 

"Use of machine-learning algorithms for 

the automated detection of cold-water 

coral habitats: a pilot study" 

Autun Purser 1 ,*, Melanie Bergmann 2 , Tomas Lundälv 3 , Jörg Ontrup 4 , 

Tim W. Nattkemper 4 

Paper 1 

Published in: 

Marine Ecology Progress Series, 397: 241-251, 2009 

1 Jacobs University, Campus Ring 1, 28759 Bremen, Germany 

2 Alfred Wegener Institute for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Germany 

3 Sven Lovén Centre for Marine Sciences, University of Gothenburg, Tjärnö, 452 96 Strömstad, Sweden 

4 Bielefeld University, Faculty of Technology, Biodata Mining & Applied Neuroinformatics Group, PO Box 100131, 

33501 Bielefeld, Germany 

25

Chapter 3 



Autun Purser 1,* , Covadonga Orejas 2,3 , Andrea Gori 2 , Laurenz Thomsen 1 , Ruiju 

Tong 1 , Vikram Unnithan 1 

Paper 2 

In preparation for submission in June 2010 to 

Marine Ecology Progress Series 


2 Instituto de Ciencias del Mar (CSIC), Pg Maritim de la Barceloneta 37-49, 08003, Barcelona, Spain 

3 Centro Oceanografico de Santander (IEO) Promontorio de San Martin s/n, 93004, Santander, Spain 

37

ABSTRACT 

Cold-water coral reefs are numerous on the Norwegian margin, and they are commonly 

described as regions of high biodiversity and as significant habitats for fish. The degree to 

which the population density of reef fauna varies spatially, across and between reefs is not 

well understood. In this study three reefs on the Norwegian margin (the Røst, Traena and 

Sotbakken reefs) were investigated by 13 manned submersible video transect surveys. 

Substrate type and population density of a selection of species were logged throughout each 

dive. Four substrate categories were used (coral structure, coral rubble, hardground, soft 

sediment). Densities of Lophelia pertusa, Madrepora oculata, Paragorgia arborea, Primnoa 

resedaeformis, Mycale lingua, Geodia baretti, Acesta excavata, fish sp. and occurrences of 

anthropogenic material were logged throughout each dive. For the gorgonian coral 

Paragorgia arborea, colony colour and size was also logged. From the dive transect data, 

the relationship between population density of each species and substrate type, reef location 

and other species was assessed by comparing density and MDS plots. The degree to which 

species occurrence was random or clumped along each dive transect was assessed with 

Morisita’s index of patchiness. 

Population structure and density for the majority of investigated species varied with both reef 

location and substrate. The majority of the sessile organisms were clumped in distribution 

and occurrence peaks often correlated with particular substrates (particularly coral substrate 

with a density of living coral polyps). A great variety in Acesta excavata densities was 

observed at the various reefs, with populations many times greater logged at the Sotbakken 

reef than elsewhere. Fish were likewise present in greatest abundance at the Sotbakken 

reef. The majority of snagged ropes and anthropogenic material was observed at the Røst 

reef, as were smaller average Paragorgia arborea colony sizes than elsewhere, indicative of 

historical levels of physical disturbance above that experienced at the other reefs. 

By focusing on a few key species, a great variation in faunal composition across and 

between reefs on the Norwegian margin is indicated by this study. 

INTRODUCTION 

Scleractinian corals such as Lophelia pertusa (Linnaeus, 1758) and Madrepora oculata 

(Linnaeus, 1758) are recognised as important components of European cold-water coral 

(CWC) reefs (Roberts et al. 2009). These azooxanthellate corals produce complex 3D 

38

calcium carbonate skeletons with growth, and provided a suitable substrate and nutrient 

supply is available reefs can develop over kilometres of the seabed, and attain heights of 

tens of meters (De Mol et al, 2002; Fosså, 2010). Although growth rates of these corals 

tends to be of a lower order than found in tropical corals (Mikkelsen et al, 1982; Orejas et al, 

2008) the lack of an algal partner allows for a vertical distribution below the photic zone. 

Developed reefs provide a host of habitat niches for other organisms (Jensen and 

Frederiksen, 1992; Rogers, 1999), by providing suitable substrates for sessile organisms 

(Roberts et al, 2006), structure for fish (Husebø et al. 2002; Costello et al, 2005) and by 

altering the hydrodynamics of bottom water flow to the benefit of filter feeding organisms 

(White et al, 2007). As reefs develop, distinct broad habitat categories are often formed 

(Wilson, 1979). Commonly, a core area of living coral is surrounded by an area of coral 

rubble - dead skeletal material broken from the main reef by bio or physical erosion. Beyond 

this rubble zone, the substrate depends on underlying geology or oceanic processes, and on 

the Norwegian margin is often soft sediment or hardground resulting from previous 

glaciations and / or the prevailing hydrodynamic conditions (Wheeler et al, 2007). 

Scientifically and commercially the protection of these CWC reefs is desirable, scientifically 

to preserve them as seafloor islands of biodiversity (Rogers, 1999; Roberts et al, 2006) and 

commercially to preserve them as habitats for commercial fish species (Mortensen et al, 

2005). 

In recent years understanding of the influence of various parameters, such as temperature 

(Dodds et al, 2007), density (Dullo et al, 2008) and nutrient availability (Kiriakoulakis et al, 

2005; Kiriakoulakis et al, 2007; Dodds et al, 2009; van Oevelen et al, 2009) on successful 

CWC reef growth has improved. From these studies techniques have been developed to try 

and predict where undiscovered reefs are likely to be located (Davies et al, 2008). 

Verification of such predictive efforts is becoming progressively easier with reef structures 

being distinguished on acoustic seabed surveys with increasing accuracy (Guinan et al, 

2008). 

These advances have allowed increasingly broad areas of the seabed to be designated as 

CWC habitat, but an understanding of how species distribution and habitat structure on the 

metre scale varies within and between these CWC habitat regions is not well understood. 

Often, knowledge of species found on a particular reef is derived from discreet grab 

sampling, box coring or historically, dredge surveys of a particular reef (Jensen and 

Frederiksen, 1992). In this study we present the results of a video investigation assessing 

how the densities of a selection of reef species can vary across and between three reefs on 

the Norwegian margin - the large Røst reef (Fosså et al. 2005), the smaller Traena reef 

39

(figure 1) and the northerly Sotbakken reef. The same survey technique was employed at 

each reef location. In addition to investigating species distributions, evidence of 

anthropogenic impacts at each of the reefs was also quantified. 

Figure 1. The Norwegian margin. Locations of investigated reefs marked. 1 - Røst reef, 2 - Traena reef, 3 - 

Sotbakken reef. 

The Norwegian margin is an important fishery (Fosså, 2010) and area of production for the 

petrochemical industry (Lepland and Mortensen, 2008). Historically, bottom trawling has 

caused considerable degradation of CWC habitats, (Fosså et al. 2000, 2002; Wheeler et al, 

40

2005), although in Norwegian waters the larger reefs are now under protective legislation 

from bottom trawling (Fosså and Skjoldal, 2010). The aim of carrying out this study was to 

quantitatively assess the individuality of these Norwegian reefs, to better understand these 

diverse ecosystems and to aid in development of future management plans. 

METHODOLOGY 

Survey sites 

Cold-water coral reefs on the Norwegian margin can be extensive and many have been 

located over recent years (Roberts et al, 2009). The interest of the offshore industry in 

exploration of the region has resulted in reef discoveries, as has concerns for the 

maintenance of viable fishing stocks. Three of these Norwegian reefs, the Røst, Traena and 

Sotbakken reefs were investigated with the 'FS Polarstern' during the ARKXXII/1a cruise, 

June 2007 (table 1, figure 1). In all cases the dominant scleractinian reef forming coral at 

each is Lophelia pertusa. All three reefs are exposed primarily to the Norwegian North 

Atlantic Current, flowing SW – NE parallel to the Norwegian coast. The shallower, less saline 

Norwegian Coastal Current runs close to all study sites, but flows at depths shallower than 

where the corals occur, and although it has a role in regional hydrography , its direct 

influence on the CWC ecosystems is probably limited (Dullo et al, 2008). 

The Røst reef is one of the most spatially extensive in Norwegian waters (Nordgulen et al, 

2006), and has been under protection from bottom trawling since 2003, soon after its 

location and scientific investigation in 2002 (Fosså et al, 2002). It is formed from a number of 

healthy coral banks on the crests of ridges formed by the Traenadjupet landslide in the 

Cenozoic (Damuth, 1978), situated on edge of the continental margin. Between each heavily 

coral populated ridge are located areas of coral rubble and less vigorously growing coral 

thickets (Wehrmann et al, 2009). 

The Traena reef area contains a number of elongated coral structures, up to ~150m in 

length, growing into the prevailing current direction on the continental shelf. Previous 

investigation has shown these coral structures to consist of a living head or front section, 

behind which is commonly found a more degraded region of coral structure with sparse fresh 

coral growth, then a surrounding area of coral rubble (Fosså et al, 2005). 

41

Prior to this study, we are unaware of any previous detailed investigations of the Sotbakken 

reef by ROV or submarine survey. At 70 o 45’N the reef is close to the northerly limit of 

(documented) Lophelia pertusa occurrence, currently marked by a reef near Hjelmsøybank 

at 71 o 21’N in the Barents Sea (Fosså et al, 2000). 

All of the reefs were associated with the continental margin and open shelf, with none of the 

coastal fjord or sill reefs (such as found at Trondheimfjord or Tisler) being investigated here. 

Video sampling 

At each reef, the manned submersible JAGO was used to collect HD quality video data with 

imbedded GMT timecode from across a variety of reef habitats. Accurate submarine 

positioning was maintained throughout the dives with the LinkQuest TrackLink 1500 HA 

positioning system. For the majority of each dive, a pair of parallel lazer pointers positioned 

50cm apart was used to provide image scale. The camera was mounted in a fixed position 

and provided a view of roughly 10m 2 of seabed, given a submarine altitude of a metre or so 

above the seafloor. Following the cruise, the videos were replayed and the occurrence of 

each substrate category and species of interest (see below) logged by timecode from a 1.5m 

wide strip (the strip being the 50cm separated by the lazer pointers, and the 50cm either side 

of this strip) throughout the videos. Following this logging stage, the submarine position data 

recorded from the LinkQuest system was used in combination with the video timecodes to 

assign a linear distance from start of transect for each logged observation. These 

observations were then binned together to form 1 x 1.5 m transect quadrats for the whole 

length of each video survey. Wherever image quality was low due to excess turbidity or 

unsuitable viewing angle, a gap was recorded in the transect data. Additionally, conductivity, 

temperature and depth readings were recorded with a standard CTD mounted on the 

submarine throughout each dive. 

Substrate categories and investigated species 

Substrate was categorized throughout each dive transect, with timecodes of substrate 

change noted and later converted to distance from the LinkQuest positioning data as 

described above. The aim of assessing substrate type was to identify any relationship 

between the densities of the various investigated organisms with substrate type. Four 

43

categories of substrate were used:- Hardground, rubble, soft and structure. Additionally, in 

regions where pebbles, rocks or cobbles were observed, they presence was also logged in 

addition to underlying substrate type (Figure 2). In some regions of the each transect two 

substrates were present within the 1.5m width transect line, and in these cases the dominant 

substrate category was assigned. 

Figure 2. Substrate categories used in the study. a) coral rubble. b) soft sediment. c) soft sediment with scattered 

stones. d) hardground. e) coral framework. 

Rather than attempt to log all observed organisms throughout all transects a selection was 

made based on ease of identification, level of previous study, ecosystem importance and 

commercial significance. No attempt was made to assess the alpha and beta-diversity 

patterns that may be present on or between reefs on the Norwegian margin. The aim was 

rather to investigate the variability in the population densities of a few key species. These 

species are described below and shown in figure 3. 

Lophelia pertusa, the most widespread and significant habitat building scleractinian coral in 

European waters (Roberts et al, 2009) was logged by live polyp coverage throughout each 

transect. Five grades of coverage were selected:- No cover, 1 – 25%, 25 – 50%, 50 – 75% 

and 75 – 100%. Given the difficulty in settlement for many sessile organisms on live L. 

pertusa, the aim of determining degree of substrate cover by live coral was to assess 

whether or not some of the investigated organisms were present at higher density in areas 

44

with lower L. pertusa coverage. Additionally, by comparing the percentages of substrate 

covered by live polyps at each reef the relative health status of each reef could be roughly 

assessed. 

Figure 3. Species investigated across the reefs. a) Lophelia pertusa b) Madrepora oculata c) Paragorgia arborea 

d) Primnoa resedaeformis e) Mycale lingua f) Geodia baretti g) Acesta excavata h and i) various fish. 

Madrepora oculata forms less expansive reef structures and is of lower structural resilience 

(Zibrowius, 1984) than Lophelia pertusa, with a widely reported distribution on the 

Norwegian margin. In this study the coral was logged by patch occurrence, as observed 

patches were not extensive in substrate coverage. 

Paragorgia arborea (Linnaeus, 1758) gorgonian coral colonies are amongst the more 

visually resplendent components of CWC ecosystems, often positioned prominently on the 

top of ridges or boulders, curving into the prevailing current. Colonies can measure meters in 

height (Smith, 2001), form distinct, brightly coloured ‘bubblegum’ colonies (Mortensen and 

Buhl-Mortensen, 2005) and provide niches for a selection of invertebrates (Buhl-Mortensen 

45

and Mortensen, 2004) and habitats for fish (Krieger, 1993). Colonies are reported as 

generally being of one of three colours:- deep pink, salmon pink or white (Mortensen and 

Buhl-Mortensen, 2005). Throughout the transects in this study P. arborea colonies were 

logged under these three colour categories, although from the video collected, differentiating 

between white and salmon pink colonies was difficult. In addition to colony colour, colony 

size was also logged for each observation. Two size categories were selected:- >50 cm and 

habitats the aim was to see to what degree substrates produced by CWC growth (rubble or 

structure) are more suitable for G. baretti colonisation than other Norwegian margin 

substrates (hardground or soft sediment). 

Acesta excavata is the largest of the bivalves commonly found in association with CWC 

habitats on the Norwegian margin (López Correa et al, 2005). Although widely reported, 

variation in population density between and across reefs has not been described in detail. 

This bivalve is often situated on the edges of vertical structures within reefs, or on the edges 

of reef crests within the live Lophelia pertusa structure. 

Fish were not logged to species level, although those commonly observed included various 

Sebastes sp., Pollachius virens and Brosme brosme. To quantify fish distribution across the 

reefs a slightly different logging strategy was used than for the other species. Each fish 

coming into the cameras field of view was logged on first observation, regardless of whether 

it actually passed within the 1.5m transect swathe. Fish densities were determined along the 

survey transects with this in mind, based on the 10 m 2 average coverage recorded by the 

HD camera. Fish densities have historically been assessed by survey trawls conducted over 

large areas (Gordon, 2001), whereas in this study the aim was to assess numbers at a 

smaller spatial scale and see if observations correlated with particular substrates or benthic 

species occurrence. 

Anthropogenic impacts were logged, and consisted primarily of observations of rubbish or 

lost fishing equipment. 

From the substrate and species observations density plots were produced for each transect. 

Where accurate positioning was not available from the LinkQuest system captured video 

was not analysed. Periodically the JAGO paused for sampling, and during these periods the 

collected video was likewise not used. 

Statistical study 

Species and substrate correlations 

Given that occurrence of individuals across a selection of substrates was logged for each 

transect, the densities of each species on each of the substrate types could be determined 

for each dive by totaling the number of individuals observed on a particular substrate type 

and dividing be the area of substrate covered by the dive transect. Since Lophelia pertusa 

47

individuals were not logged, (rather the percentage cover of the seabed as described 

above), for this species presence / absence for each meter of transect was used instead. 

From these results the densities of each species on each of the four substrate categories 

was computed for each dive transect. 

To determine whether variations in community structure correlated more with substrate or 

reef location, multi-dimensional scaling (MDS) plots were produced from the species density 

data logged for each substrate during each dive. The PRIMER 6 software (Clarke, 1993) 

was used to produce the plots using a 4.2 GB quad-core desktop PC. Fourth root 

transformed data was used for this analysis, to reduce the significance of the higher density 

species in the plot. 

Species distribution patterns 

Morisita's index of patchiness (Morisita, 1959) was used to assess whether individuals or 

colonies of the target species tended to be distributed randomly along the dive transects, or 

whether they tended to be more clumped together. The index is the scaled probability that 

two individuals present on a survey transect will be present in the same transect quadrat. 

Scores below 1 indicate a reasonably random distribution, with higher scores indicating a 

progressively greater degree of clumping. Given the lack of homogeneity within the dive 

transects, only sections of transect data where substrate type was stable for >20 m was 

used in computing this index score. Following analysis of all dive data from a particular reef, 

the average Morisita's index score for each species on each substrate type was determined 

for each reef. 

Paragorgia arborea colour and size variations 

Statistical analyses were carried out using the program SPSS v. 17.0. One-way ANOVA 

tests were used to determine whether average colony colour differed significantly between 

reef sites. One-way ANOVA tests were also carried out to see whether there was a 

significant difference in colony size between reef sites. All data was tested against a 

significance level of 0.05. In cases where the collected data did not meet the ANOVA test 

criteria of regular distribution or homogeneity of variance, the Kruskal-Wallis test was applied 

48

instead. Post-hoc testing for ANOVA tests was carried out using a LSD test, with a Mann- 

Whitney U test used for post-hoc analysis of Kruskal-Wallis test results. 

Results 

Species density variation 

Species densities observed varied significantly with both changes in substrate and transect 

location. Table 2 shows that densities could vary on a local scale, with differing densities for 

most species being observed on sections of transects carried out over a particular substrate 

category at different locations on the same reef. The total lengths of each of the four 

substrates surveyed during each dive varied considerably, and in some cases not all four 

substrate types were observed during a particular dive. No hardground substrate was 

observed during dives at the Sotbakken or Traena reefs. Some of the comparatively high 

and low population densities presented in the table from dives over small areas of substrate 

(such as rubble substrate during Røst dives 1 and 2), are likely the result of this patchiness 

of sampling rather than greatly different population densities (e.g. over rubble substrate 

during Røst dives 3, 4, 5, 7 and 8) . Figures 4 (Røst dive 5), 5 (Traena dive 1) and 6 

(Sotbakken dive 1) show representative population density plots from each of the surveyed 

reefs. The density plots produced from the other 10 dive transects are available in the 

ONLINE SUPPLIMENTARY MATERIAL. 

49

Table 2. Species densities observed on each substrate type throughout each of the survey transects. 

50

Figure 4. Species density plot produced from the quadrat transect data from Røst dive 5. Colours indicate 

substrate type. Green - soft sediment, red - coral rubble, purple - structure, black - hardground. In quadrats 

where cobbles, stones or boulders are present, a black bar is shown in the substrate section. Anthropogenic 

material is represented by asterisks. 

51

Figure 5. Species density plot produced from the quadrat transect data from Traena dive 1. Colours indicate 




52

Figure 6. Species density plot produced from the quadrat transect data from Sotbakken dive 1. Colours indicate 




Figure 7 shows that the average densities observed for each species differs between reefs, 

and with substrate. In general, species were observed in higher densities at the Røst reef 

than at the Traena or Sotbakken reefs. Density variation between reef sites is described by 

species below. Figure 8 shows the MDS plots derived from the species abundance and 

substrate category data from each dive. 

53

Figure 7. Average density of each species observed at each reef over each substrate type. ND represents no 

substrate of that category observed during dives. 

54

Figure 8. MDS plots of fourth root transformed abundance data from each substrate type surveyed during each 

of the JAGO dives. a) plot with reef location as factor b) plot with substrate type as factor, with dive numbers 

additionally plotted. 

Lophelia pertusa 

At the Røst and Sotbakken reefs, living Lophelia pertusa was found at least at low density 

within almost 100% of every m 2 of framework substrate. At the Traena reef 10% of substrate 

m 2 did not contain any living L. pertusa. Live L. pertusa was present in ~50% of rubble 

transect quadrats at the Røst reef, ~15% at the Traena reef and 0% of rubble quadrats at 

the Sotbakken reef. Approximately 25% of soft substrate quadrats at the Røst reef contained 

live L. pertusa, (growing on isolated stones in some dive transects) with

100 

75 

50 

25 

0 

Rost Traena Sotbakken 

75 to 100 

50 to 75 

25 to 50 

1 to 25 

0 

Figure 9. Lophelia pertusa polyp coverage of structure substrate at each reef. Lophelia pertusa coverage 

estimates are based on the % of each transect quadrat covered by live L. pertusa. 

Madrepora oculata 

Differentiating Madrepora oculata from Lophelia pertusa can be problematic from a distance. 

On the Norwegian margin both scleractinians can be either white or orange in surface 

colouration, and although growth morphology can be distinctive at close range, at a distance 

the difference in polyp branching between the two species was more difficult to identify. It 

was particularly difficult to pick the two corals apart in areas of high density coral growth. The 

generally darker background afforded by growth in less densely populated areas (such as on 

hardground, rubble, or on cobbles amongst soft sediments) made the task easier. Because 

of this the colony density results for this organism presented here should be considered with 

a degree of caution. 

No Madrepora oculata colonies were observed from either the Traena or Sotbakken reef 

sites. Densities of M. oculata patches on the Røst reef were low. Density was observed to be 

highest on rubble substrate regions, ~0.014 colonies m -2 . Lower densities of ~0.009, 0.008 

and 0.006 colonies m -2 were observed on hardground, soft and structure substrates 

respectively. 

56

Primnoa resedaeformis 

This gorgonian was found at all three reef sites, with densities highest at each on structure 

substrates. At the Røst reef an average density on structure substrate was ~0.21 colonies m - 

2 -2 

, with lower densities of ~0.13 and ~ 0.03 colonies m observed on comparable substrate at 

the Traena and Sotbakken reefs respectively. At the Røst reef an average density of ~0.11 

colonies m -2 was logged on hard substrates, with ~0.05 colonies m -2 on rubble substrates. A 

very low density (90% respectively. At the Røst 

Reef an average density of 0.05 colonies m -2 was observed on hardground. Very low 

densities (50cm in height did differ significantly between reefs (ANOVA, 

F(2,10)=14.31, p=0.01). The Sotbakken and Traena reef colonies were significantly larger 

than those observed at the Røst reef (LSD, p=0.004 and p=0.001 respectively). Figure 10 

shows that ~20% of colonies observed at Røst reef were of >50cm height, whereas at the 

Sotbakken and Traena reefs ~80% of observations made were of colonies >50cm in height. 

Colony colour did not vary significantly between sites. As figure 11 shows, >60% of colonies 

at the Røst and Sotbakken reefs were white in colour, with the colours of the remaining 

colonies being divided roughly equally between red and salmon. At the Traena reef, the 

percentage of colonies of each colour was roughly equal, at ~33%. The sizable standard 

deviation observed at each reef site is indicative of a considerable variation in colouration 

observed across the various dives at each reef. 

57

100 

75 

50 

25 

0 

Rost Sotbakken Traena 

Figure 10. Average Paragorgia arborea size variation observed at Røst, Sotbakken and Traena reefs. White 

boxes represent colonies 50cm in length. . Error bars represent 1 SD. 

100 

75 

50 

25 

0 

Rost 

Sotbakken 

Traena 

Figure 11. Average Paragorgia arborea colony colour variation observed at Røst, Sotbakken and Traena reefs. 

White boxes represent white coloured colonies, black boxes represent deep pink colonies and grey boxes 

represent salmon coloured colonies. Error bars represent 1 SD. 

59

Wherever observed in numbers during video transects, patchiness in distribution was 

indicated for Paragorgia arborea colonies (Table 3). 

Fish 

Average fish densities observed varied with both substrate and reef. The greatest densities 

were observed at the Sotbakken reef, where densities of ~0.03 and 0.025 individuals m -2 

were recorded above rubble and structure substrates respectively. At the Røst and Traena 

reef highest densities were observed in association with structure substrates, with individual 

densities of ~0.015 and ~0.012 fish m -2 respectively. At the Røst reef an average density of 

~0.005 fish m -2 was observed across hardground, rubble and soft substrates. A comparable 

density was also observed above soft sediments at the Sotbakken reef. No fish were 

observed at the Traena reef above soft substrates, and a comparatively low abundance of 

~0.002 fish m -2 were found in association with rubble substrate. 

Although species identification was not considered in this analysis, the utilization of certain 

habitats by some species was apparent. Some species, such as Brosme brosme was often 

spotted in cracks within coral structure (figure 3), Sebastes sp. were also observed using 

these shelters. The use of such features and the ability fish had to disappear following 

disturbance by the submarine may indicate underestimations in the individual densities for 

such habitats presented here. Distribution pattern varied considerably from reef to reef and 

substrate to substrate (figures 4, 5, 6, table 3). 

Mycale lingua 

These sponges were found in greater abundance across all substrates at the Røst reef than 

across comparable substrates at other reefs. By far the greatest average density was 

observed on structure substrate at the Røst reef, with >0.8 individuals m -2 being observed. 

~0.21 individuals m -2 were observed in association with rubble substrates at the reef, with 

~50% less being observed in hardground and soft quadrats. At the Traena reef an average 

~0.1 individuals m -2 were present on structure and rubble substrates, with ~0.025 m -2 in soft 

sediment transect quadrats. At the Sotbakken reef, the average highest density was again 

observed on structure substrates (0.015 individuals m -2 ), with

Geodia baretti 

Overall most abundant in association with the Røst reef, this sponge was averaged higher 

densities on substrates other than structure at all reef sites. At Røst, average densities of 

~0.2 individuals m -2 were observed across hardground, rubble and soft sediment quadrats, 

with a 60% lower density observed on structure substrates. At the Traena reef no individuals 

were observed in soft sediment quadrats, and average densities of ~0.1 and ~0.05 

individuals m -2 were observed on rubble and structure substrates respectively. Average 

densities of ~0.05 m -2 were found across rubble, soft and structure substrates at the 

Sotbakken reef. Generally one of the most randomly distributed of the investigated species 

(Table 3). Large densities and a high patchiness were indicated on some areas of soft 

sediment at the Sotbakken reef. 

Acesta excavata 

Differences in abundance of this species across reefs and substrates were pronounced. 

Only 2 individuals were logged at the Røst reef (table 2), on structure substrate. A few 

patches of individuals were logged at the Traena reef, on both rubble and structure 

substrates, giving estimated average densities of ~0.01 and ~0.025 individuals m -2 

respectively. At Sotbakken, however, great swathes of structure substrate contained high 

densities of individuals, giving an average density of ~2.1 individuals m -2 across that 

substrate. Distribution was patchy (table 3), often with shells lining the underside of any 

overhangs in the coral structure. No individuals were observed at the reef in association with 

any other substrate type. 

Anthropogenic material 

Clear evidence of anthropogenic damage or human activity was surprisingly sparse 

throughout the various dive transects. Lost ropes were periodically observed on the Røst 

reef in particular, with a lesser number observed on the Traena reef. No lost nets were 

observed during any of the survey dives. No ropes were observed at the Sotbakken reef. 

Occasional pieces of plastic rubbish were observed across all dives, particularly at the Røst 

and Traena reefs. 

61

Discussion 

General reef morphology 

Species utilization of the various available substrate types varied greatly across and 

between the three reefs investigated in this study. Broad differences in Lophelia pertusa 

coverage of structural substrate were expected between the Røst and Traena reefs, 

following previous investigations of the two sites (Fosså et al, 2005). Nutrient supply to the 

various reefs was not investigated in this study, but consumption of any fresh material 

delivered to the Traena reefs by the live high density Lophelia pertusa ‘head’ sections of the 

elongated structures could well account for the variability in coverage by live L. pertusa 

observed. The higher flows found on the edge of the continental slope and possible Ekman 

transport of fresh material to the Røst reef (Thiem et al, 2006), could provide the higher 

nutrient input required for the more substantial reef growth observed there. The Sotbakken 

reef transects showed significant reef development, with the large, cauliflower shaped 

mounds associated with healthy reef growth much in evidence. 

Species distributions 

Generally, most species or groups investigated were observed in greater abundance at the 

Røst reef than at the Traena or Sotbakken reefs. 

One of the most striking differences between the reefs investigated was the near total 

absence of Acesta excavata from the Røst reef. Despite being the subject of 8 survey dives, 

only 2 A. excavata individuals were observed. On one of the two Traena reef dives ~25x this 

number were observed, although none were logged on the other Traena dive. Although not 

greatly studied, A. excavata are hypothesised to be adapted for regions of low, steady 

temperature and / or poor food availability (Järnegren and Altin, 2006). Given the 

comparable temperatures observed at the Røst and Traena reef during this study it is 

unlikely that variations in temperature between these two spatially close reefs accounts for 

their abundance at one site and near absence at the other. Occurrence of A. excavata 

individuals at the Traena reef correlates closely with the peaks in Lophelia pertusa coverage 

density. This indicates that only the head sections of the Traena reef elongated structures 

are suitable for their growth, perhaps allowing them to filter a large volume of suspended 

material reaching the reef before other filter feeders (even if of a low lability) or utilise first 

any periodic deliveries of fresh material. Both these strategies have been proposed as 

62

feeding strategies for L. pertusa in certain locations (Davies et al, 2009) and under different 

nutrient availability regimes (Kiriakoulakis et al, 2005). The pattern of A. excavata 

distribution at the Sotbakken reef is however very different. Wherever L. pertusa structure 

was observed, A. excavata were also observed in great abundance, with density peaks in 

one species appearing to be unrelated to density peaks in the other (figure 5). The healthy 

L. pertusa reef structure apparent at the Sotbakken site does not indicate a lack of suitable 

food reaching the reef, for L. pertusa growth at least. A possible explanation for the high A. 

excavata abundance at this reef could be its facility to filter very large volumes of water 

swiftly at low temperatures despite maintaining a low respiration rate (Järnegren and Altin, 

2006), not a characteristic shared by L. pertusa (Dodds et al, 2007), allowing it some 

advantage in settlement and establishment in the colder waters. 

Fish densities varied with both substrate and reef. Generally, fish densities were higher in 

association with reef structure substrate than the other substrate types, with structure clearly 

providing niches for various species as previously observed (Husebø et al, 2002). Fish were 

observed in highest density at the Sotbakken reef, with >0.025 individuals m -2 observed in 

association with both rubble and structure substrates. As can be seen from the density plots, 

periodic shoals of numerous fish were more common at this reef than at the Røst or Traena 

reefs, with these accounting for a percentage of the greater abundance. 

The densities of the gorgonians varied greatly with substrate and reef. Primnoa 

resedaeformis and Paragorgia arborea were logged at comparable concentrations across 

each substrate at the Røst and Traena reefs, but at the Sotbakken reef colonies of P. 

resedaeformis were observed in far fewer numbers than those of P. arborea. The 

temperature difference between Sotbakken and the other two reefs is unlikely to be the 

cause of this difference, with temperatures from both sites (at time of study) comfortably 

within ranges reported for both species (Leverette and Metaxas, 2005; Bryan and Metaxas, 

2007). The two species utilise slightly different food sources. P. arborea often grows near 

vertically into the stronger, less-turbulent waters found above the seabed (Wainwright and 

Dillon 1969; Warner 1977), as observed generally across reefs in this study, whereas P. 

resedaeformis tends to form loosely branched colonies draped on or just above the seabed, 

with such a growth form tending to represent utilisation of more turbid waters, commonly 

containing more degraded, resuspended material for nutrient supply. P. resedaeformis 

throughout the transects studied occupied a similar niche to Acesta excavata, with 

potentially the bivalve outperforming the gorgonian in utilising this nutrient supply at the cold, 

northerly Sotbakken reef, occupying much of the substrate available to the two organisms. 

63

Paragorgia arborea varied significantly in both colony size and abundance between reef 

locations. Although present in densities of ~0.25 colonies m -2 on structure substrates at both 

the Røst and Sotbakken reefs (a lower density of ~0.15 colonies m -2 on comparable 

substrate at Traena reef), average colony size was considerably smaller at the Røst reef 

than at the other two reef sites. Although in this study colony height was divided into just two 

categories, > and

some morphological or flow regime feature associated with the reef bank structure is 

unclear. Densities of the sponge were ~40% lower at the less fished Sotbakken reef, 

however. 

Anthropogenic impacts 

Clear evidence of anthropogenic impact on the reefs was limited to the scattered rubbish 

observed across the various reefs, and the lost ropes present amongst the coral structure 

(and occasionally rubble areas) of the Røst and Traena reefs. The various survey dives were 

chosen with the aim of investigating as great a range of reef habitats as possible, and did not 

focus on the edges of the reef regions, those often damaged more extensively by fishing 

activity (T Lundälv, pers comm.). The smaller, likely younger Paragorgia arborea colonies 

observed at the Røst reef, particularly in combination with the greater number of lost ropes 

observed at that reef, do indicate a greater degree of physical disturbance there than at the 

other reefs. The pieces of plastic rubbish logged during the dive transects are probably just a 

fraction of those trapped and incorporated into the reef. During breaks in the collection of 

transect data required for fauna sampling, the submarine cameras were often used for 

surveying the region around the sample. Often, during these close-up video sequences, 

small pieces of plastic material could be seen within the coral structure. 

Conclusions 

By using a uniform sampling technique and by focusing on densities of a few select species 

a considerable variety in the faunal composition across the various Norwegian reefs is 

indicated. Substrate was observed to be the defining factor in habitat selection for many 

species, but on the regional scale, utilisation of comparable habitat at the different reefs was 

observed to be very different for some species. Variable nutrient delivery or the variable 

ability of the species to utilise nutrients under different flow and temperature regimes may 

explain a percentage of these observations, with fishing activity probably impacting on 

gorgonian colony size at the Røst reef. Given the variety in species composition and species 

population densities indicated by this study, management plans for the CWC regions of the 

Norwegian margin should not be based around the assumption that all areas of the seabed 

labelled as CWC habitat are comparable and interchangeable in morphology or population 

composition. Reefs with broadly similar live Lophelia pertusa substrate coverage can clearly 

have quite a different associate fauna population. 

65

Acknowledgements 

This work was funded by Statoil and the FP6 EU-project HERMES (EC contract no GOCE- 

CT-2005-511234) and is a CORAMM group collaboration. We would like to thank the onboard 

scientific party and crew of ARKXXII-1A for their assistance in producing this work, 

particularly the IFM-GEOMAR JAGO team (J.Schauer, K. Hissmann, S. Floegel and A. 

Rüggeberg). 

References 

Andrews AH, Cordes EE, Mahoney MM (2002) Age, growth and radiometric age validation 

of a deep-sea, habitat-forming gorgonian (Primnoa resedaeformis) from the Gulf of Alaska. 

Hydrobiologica 471: 101-110 

Broch H (1912) Die Alcyonarien des Trondhjemsfjordes II. Gorgonacea. Kgl Norske Vidensk 

Selskabs Skrifter 2: 1-48 

Bryan TL, Metaxas A (2007) Predicting suitable habitat for deep-water gorgonian corals on 

the Atlantic and Pacific continental margins of North America. Mar Ecol Prog Ser 330: 113- 

126 

Buhl-Mortensen L, Mortensen PB (2004) Crustaceans associated with the deep-water 

gorgonian Paragorgia arborea (L., 1758) and Primnoa resedaeformis (Gunnerus, 1763). J 

Nat His 38: 1233-1247 

Clarke KR (1993) Non-parametric multivariate analyses of changes in community structure. 

Aust J Ecol 18: 117-143 

Costello M, McCrea M, Freiwald A, Lundälv T, Jonsson L, Bett B, Weering T, Haas H, 

Roberts J, Allen D (2005) Role of cold-water Lophelia pertusa coral reefs as fish habitat in 

the NE Atlantic. In: Freiwald A, Roberts JM (eds) Cold-Water Corals and Ecosystems, 

Springer, Berlin, p 771-805 

Damuth JE (1978) Echo Character of Norwegian-Greenland Sea: Relationship to Quaternary 

Sedimentation. Mar Geol 28: 1-36 

Davies AJ, Wisshak M, Orr JC, Murray Roberts J (2008) Predicting suitable habitat for the 

cold-water coral Lophelia pertusa (Scleractinia). Deep Sea Res Pt I 55: 1048-1062 

Davies, AJ, Duineveld GCA, Lavaleye MSS, Bergman MJN, van Haren H, Roberts JM 

(2009) Downwelling and deep-water bottom currents as food supply mechanisms to the 


54(2): 620-629 

66




Dodds LA, Roberts JM, Taylor AC, Marubini F (2007) Metabolic tolerance of the cold-water 

coral Lophelia pertusa (Scleractinia) to temperature and dissolved oxygen change. J Exp 

Mar Biol Ecol 349: 205-214 



Prog Ser 397: 113-124 

Dullo WC, Flögel S, Rüggeberg A (2008) Cold-water coral growth in relation to the 

hydrography of the Celtic and Nordic European continental margin. Mar Ecol Prog Ser 371: 

165-176 

Fosså JH, Skjoldal HR (2010) Conservation of Cold-Water Coral Reefs in Norway. In: 






Fosså JH, Mortensen PB, Furevik DM (2000) Lophelia-korallrev langs norskekysten 

forekomst og tilstand. Fisken og Havet 2: 1-94 






Gordon JDM (2001) Deep-water fisheries at the Atlantic Frontier. Cont Shelf Res 21: 987- 

1003 

Guinan J, Grehan AJ, Dolan MFJ, Brown C (2009) Quantifying relationships between video 

observations of cold-water coral cover and seafloor features in Rockall Trough, west of 

Ireland. Mar Ecol Prog Ser 375:125-138 

Heifetz J (2002) Coral in Alaska: distribution, abundance, and species associations. 

Hydrobiologica 471: 19-28 

Henry LA (2001) Hydroids associated with deep-sea corals in the boreal north-west Atlantic. 

J Mar Biol Assoc UK 81: 163-164 

Husebø A, Nøttestad L, Fosså JH, Furevik DM, Jørgensen SB (2002) Distribution and 

abundance of fish in deep-sea coral habitats. Hydrobiologica 471: 91-99 

Järnegren J, Altin D (2006) Filtration and respiration of the deep living bivalve Acesta 

excavata (J.C. Fabricius, 1779) (Bivalvia; Limidae). J Exp Mar Biol Ecol 334: 122-129 

Jensen A, Frederiksen R (1992) The fauna associated with the bank-forming deepwater 

coral Lophelia pertusa (Scleractinaria) on the Faroe shelf. Sarsia 77: 53-69 

67

Kiriakoulakis K, Fisher E, Wolff GA, Freiwald A, Grehan A, Roberts JM (2005) Lipids and 

nitrogen isotopes of two deep-water corals from the North-East Atlantic: initial results and 

implications for their nutrition. In: Freiwald A, Roberts JM (eds) Cold-Water Corals and 




96: 159-170 

Krieger KJ (1993) Distribution and abundance of rockfish determined from a submersible 

and by bottom trawling. Fisheries Bulletin 91: 87-96 

Krieger KJ, Wing BL (2002) Megafauna associations with deepwater corals (Primnoa spp.) 

in the Gulf of Alaska. Hydrobiologica 471: 83-90 



56: 119-129 

Leverette TL, Metaxas A (2005) Predicting habitat for two species of deep-water coral on the 

Canadian Atlantic continental shelf and slope. In: Freiwald A, Roberts JM (eds) Cold-Water 

Corals and Ecosystems, Springer, Berlin, p 467-479 

López Correa M, Freiwald A., Hall-Spencer J, Taviani M (2005) Distribution and habitats of 

Acesta excavata (Bivalvia: Limidae) with new data on its shell ultrastructure. In: Freiwald A, 

Roberts JM (eds) Cold-Water Corals and Ecosystems, Springer, Berlin, p 173-205 

Mikkelsen N, Erlenkeuser H, Killingley JS, Berger WH (1982) Norwegian corals: radiocarbon 

and stable isotopes in Lophelia pertusa. Boreas 11: 163-171 

Mortensen PB, Buhl-Mortensen L (2005) Morphology and growth of the deep-water 

gorgonians Primnoa resedaeformis and Paragorgia arborea. Mar Biol 147: 775-788 

Mortensen PB, Buhl-Mortensen L, Gordon DC (2005) Effects of fisheries on deepwater 

gorgonian corals in the Northeast Channel, Nova Scotia. In: Barnes PW, Thomas JP (eds) 

Benthic Habitats and the Effects of Fishing. American Fisheries Society Symposium 41: 369- 

382 

Nordgulen O, Bargel TH, Longva O, Ottesen D (2006) A preliminary study of Lofoten as a 

potential World Heritage Site based on natural criteria. Geological Survey of Norway 

Orejas C, Gori A, Gili JM (2008) Growth rates of live Lophelia pertusa and Madrepora 

oculata from the Mediterranean Sea maintained in aquaria. Coral Reefs 27: 255 

Purser A, Bergmann M, Lundälv T, Ontrup J, Nattkemper T (2009) Use of machine-learning 

algorithms for the automated detection of cold-water coral habitats: a pilot study. Mar Ecol 

Prog Ser 397: 241-251 

Roberts JM, Wheeler AJ, Freiwald A (2006) Reefs of the Deep: The Biology and Geology of 

Cold-Water Coral Ecosystems. Science 312: 543-547 


Geology of Deep-Sea Coral Habitats. Cambridge, UK 

68



Thiem Ø, Ravagnan E, Fosså JH, Berntsen J (2006) Food supply mechanisms for coldwater 

corals along a continental shelf edge. J Marine Syst 60: 207-219 

Van Oevelen D, Duineveld G, Lavaleye M, Mienis F, Soetaert K, Heip CHR (2009) The coldwater 

coral community as a hot spot for carbon cycling on continental margins: A food-web 

analysis from Rockall Bank (northeast Atlantic). Limnol Oceanogr 54(6): 1829-1844 

Wainwright SA, Dillon JR (1969) On the orientation of sea fans (genus Gorgonia). Biol Bull 

136: 130-139 

Warner GF (1977) On the shapes of passive suspension feeders. In: Keegan BF, Ceidigh 

PO, Boaden PJS (eds) Biology of benthic organisms, Pergamon, Oxford, p567-576 

Wehrmann LM, Knab NJ, Pirlet H, Unnithan V, Wild C, Ferdelman TG (2009) Carbon 

mineralization and carbonate preservation in modern cold-water coral reef sediments on the 

Norwegian shelf. Biogeosciences 6: 663-680 

Wheeler AJ, Bett BJ, Billet DSM, Masson DG, Mayor D (2005) The impact of demersal 

trawling on northeast Atlantic deepwater coral habitats: the case of the Darwin Mounds, 

United Kingdom. In: Barnes PW, Thomas JP (eds) Benthic Habitats and the Effects of 

Fishing. American Fisheries Society Symposium 41: p 807-817 

Wheeler AJ, Beyer A, Freiwald A (2007) Morphology and environment of deep-water coral 

mounds on the NW European margin. Int J Earth Sci 96: 37-56 

Wilson JB (1979) 'Patch' development of the deep-water coral Lophelia pertusa (L.) on 

Rockall Bank. J Mar Biol Assoc UK 59: 165-177 



Zibrowius H (1984) Taxonomy in ahermatypic scleractinian corals. Palaeontographica 

Americana 54: 80-85 

69

Chapter 4 


concentration on Lophelia pertusa (Scleractinia) zooplankton capture 

rates" 

Autun Purser 1,* , Ann I. Larsson 2 , Laurenz Thomsen 1 , Dick Van Oevelen 3 

Paper 3 

Submitted to: 

Journal of Experimental Marine Biology and Ecology 

February 2010 

Returned with minor revisions requested: 

April 2010 

Revised version to be returned to journal: 

June 2010 


2 Department of Marine Ecology, University of Gothenburg, Tjärnö, SE-452 96 Strömstad, Sweden 

3 Centre for Estuarine and Marine Ecology, Netherlands Institute of Ecology (NIOO-KNAW), POB 140, 4400 AC 

Yerseke, The Netherlands 

70

ABSTRACT 

Lophelia pertusa is the most significant framework building scleractinian coral in European 

seas. Many fundamental questions about the mode of life of the species however, remain 

unanswered. Reproduction, longevity, growth and food uptake rates are still poorly 

understood. In this work an experimental investigation into the ability of L. pertusa to capture 

zooplankton from suspension was conducted. By direct ROV sampling ~350 L. pertusa 

polyps were collected from the Tisler reef, Norway and maintained in temperature controlled 

conditions in recirculating flumes. These polyps were subdivided into three groups of ~120 

polyps and maintained in waters with flow velocities of 0.025 m s -1 or 0.05 m s -1 . Suspended 

Artemia salina nauplii food concentrations of between 345 and 1725 A. salina l -1 were 

introduced. L. pertusa net capture rates were assessed by monitoring the reduction in 

suspended A. salina concentration in each flume over 24 hrs. Maximum observed net 

capture rates were higher in flumes with a 0.025 m s -1 flow regime (74.6 A. salina polyp -1 hr -1 

/ SD 27.2) than those with 0.05 m s -1 flow (27.1 A. salina polyp -1 hr -1 / SD 12.9). Net capture 

rates were lower in flumes with A. salina densities of

found in many regions of the world ocean (Wilson, 1979; Roberts et al., 2006), often many 

meters in height and km 2 in coverage area (De Mol et al., 2002), implying that the longevity 

of such reefs is in the order of 100 to 1,000 ky. The extent of these calcium carbonate 

skeletons may make L. pertusa reefs significant long-term carbon storage reservoirs (van 

Weering et al., 2003; Noé et al., 2006). 

It is hypothesised that Lophelia pertusa reefs are hotspots of biodiversity (Henry and 

Roberts, 2007) and carbon cycling on continental margins (Van Oevelen et al., 2009) and 

potentially of commercial significance for fisheries, with their variegated structure providing 

refuge for juvenile fish (Costello et al., 2005). This hypothesis is particularly prescient on the 

Norwegian Margin where L. pertusa reefs are particularly well-developed (Mortensen et al., 

2001) and where fishery activity is high (Fosså et al. 2002; Hall-Spencer et al., 2009). The 

Norwegian Margin is also a region where the offshore hydrocarbon industry is in operation, 

and there is concern to understand and minimise any potential impact of this industry on reef 

ecosystems (Lepland and Mortensen, 2008). In Norway, and progressively elsewhere in 

European waters, the location of new reefs is followed swiftly by the instigation of protective 

legislation (such as fishing exclusion zones) aimed at protecting these sites (Davies et al., 

2007). A host of environmental factors influence reef distribution, with food availability and 

suitability of substrate being of paramount importance (Hirzel et al., 2002; Davies et al., 

2008). Moreover, Lophelia pertusa reefs are associated with regions of elevated current 

velocities at the sediment, e.g. on seamounts and carbonate mounds (Dorschel et al., 2005; 

Huvenne et al., 2007), shelf margins (Fosså et al., 2002) or sills (Jonsson et al., 2004). At 

many of these sites, however, there are also periodic low flow velocities, often associated 

with tides (Davies et al., 2009). 

At Lophelia pertusa reef sites, living polyps form a thin surface layer on top of the dead 

skeletal material laid down by previous generations (Riding, 2002), and these can produce a 

mucus layer to assist in cleaning and possibly food capture. The dead skeletal reef material 

provides a varied habitat for both sessile and mobile benthic organisms (Mortensen et al., 

1995). The complex reef structure can also greatly influence the local hydrodynamics 

(Dorschel et al., 2007; Roberts et al., 2008). 

The diet of Lophelia pertusa has been investigated by analysis of stable isotope values 

(Duineveld et al., 2004) and fatty acid composition (Kiriakoulakis et al., 2005) of polyp 

samples collected from cold-water coral carbonate mounds of the northeast Atlantic (;. 

These direct analyses indicate that the diet of L. pertusa varies from site to site, and that the 

organism may well be generally heterotrophic, taking whatever is available from the water 

72

column, as is observed in other scleractinian corals (Sebens et al., 1996; Rosenfeld et al., 

2003; Houlbreque et al., 2004; Van Oevelen et al., 2009). Samples collected with sediment 

traps or in-situ pumps have shown a great variety both temporally and spatially in the quality 

of organic material entering the reefs, either in suspension within bottom currents or from 

sinking / advection (Kiriakoulakis et al., 2007; Dodds et al., 2009). 

Although there have been a host of experimental investigations of prey capture rates carried 

out with tropical scleractinian corals or gorgonians ( Coles, 1969; Sebens and Johnson, 

1991; Sebens et al., 1996; Ferrier-pages et al., 2003; Hii et al., 2009 ) and other anthozoans 

(Anthony, 1997) few have been conducted with scleractinian cold-water corals (Tsounis et 

al., 2010). The objective of this study was to investigate in the laboratory whether the ability 

of Lophelia pertusa to capture zooplankton from suspension is influenced by either flow 

velocity or food density. Such information would not only add to the current level of 

understanding of this important organism, but also to improve the accuracy of models 

attempting to predict reef distribution from oceanographic data. Assessing the maximum 

amount of food which the coral polyps can capture under varying flow and food availability 

scenarios could also assist in determining the significance of the reefs in carbon storage. 

Two hypotheses were investigated - 1) that the food capture rate of Lophelia pertusa 

increases with flow velocity increase, and 2), that the food capture rate of L. pertusa 

increases with increasing food availability. 

This work was carried out as part of the Coral Risk Assessment, Monitoring and Modelling 

(CORAMM) project and as such the results from this study are intended to feed into a 

Dynamic Energy Budget (DEB) model for Lophelia pertusa being developed by project 

partners. This DEB model is aimed at assisting in the development of risk assessment and 

mitigation strategies for the activities of the offshore hydrocarbon industry and fisheries in 

European waters, by allowing various possible scenarios to be modelled. The rate of food 

capture under various flow regimes is an important consideration in modelling reef health. 

2. Materials and Methods 

2.1 Sample site and sampling technique 

The live coral fragments used in this study were collected from the Tisler reef in the 

Norwegian section of the Skagerrak, several km north of the Swedish border, first surveyed 

in 2002 (Lavaleye et al., 2009). The reef forms an elongated structure ~1200m by ~200m on 

73

a sill between the Tisler islands and the Norwegian mainland, in water depths of 70-155 m. 

The reef is made up of a large number of ~2m diameter, ~1m high Lophelia pertusa thickets 

surrounded by fields of coral rubble (Purser et al., 2009). In some areas the thickets have 

merged into larger horizontal structures but there is little of the vertical growth apparent at 

some L. pertusa reef sites, such as those found on the Norwegian continental margin 

(Mortensen et al., 2001; Freiwald et al., 2002) or the Porcupine Seabight (Huvenne et al., 

2007). Free stream velocities over the sill can vary between 0 and 0.4 m s -1 throughout the 

year (H. Wagner, unpublished data). 

The composition of particulate material entering the Tisler reef has been investigated in 

several studies (Kiriakoulakis et al., 2005) and in-situ pump collections have shown 

periodically high concentrations of fresh phytoplankton and zooplankton swimmers within the 

bottom waters at the site during spring and summer (Lavaleye et al., 2009). Investigation by 

Remote Operated Vehicle (ROV) has shown extensive trawl damage to the reef and 

Norwegian fishery regulations protecting the reef from further bottom trawling were put in 

place in 2003. Due to the sensitivity of the ecosystem selective sampling was carried out 

using the specially modified arm of a Sperre SubFighter 7500 DC ROV in July 2008. 

Approximately 350 polyps were collected from one of a number of trawl-displaced coral 

blocks originating in a less pristine section of the reef ( 58° 59.695 N; 10° 58.240 E). During 

collection by ROV, the coral branches were broken into fragments each containing between 

10 and 50 polyps. These fragments were placed in a collection drawer on the ROV for return 

to the surface. On deck they were transferred swiftly into a large coolbox filled with 8 o C 

bottom water and transported to the Sven Loven Centre for Marine Sciences, Tjärnö, 

Sweden. The total transport time from seabed to Sven Loven Centre was less than 2 hrs. 

2.2 Lophelia pertusa preparation 

At the Sven Loven Centre the Lophelia pertusa fragments were transferred to a 

thermoconstant laboratory room maintained at 8 o C. The fragments were then further divided 

manually by cracking with latex-gloved fingers into 45 fragments, each consisting of between 

5 and 25 live polyps. Each of these new fragments was then photographed using a Fujifilm 

E900 9.0 megapixel digital camera and placed on a plastic grid in one of three flow-through 

25l plastic aquaria. Each aquarium was delivered sand-filtered seawater direct from the 

Kosterfjord from a depth of 45m at a rate of ~2 l min -1 . These coral fragments were 

maintained under these conditions for three weeks prior to the commencement of the 

experimental investigations, with a daily dose of ~0.5g freshly hatched Artemia salina nauplii 

74

delivered to each aquarium. The Sven Loven Centre has maintained L. pertusa successfully 

for a number of years under these flow and feeding regimes. 

Each Lophelia pertusa fragment was numbered and number of living polyps counted. The 

diameter of each living polyp cup was determined by analysing the photographs with the 

ImageJ 1.42q software application using a 4 gigabyte quad-core desktop PC. 

Following completion of the experimental runs, the buoyant weight of the coral fragments in 

each flume was determined as described in Davies (1989). The coral fragments were 

weighed in seawater of 8 °C and salinity of 33. Total buoyant weights, number of polyps, and 

polyp feeding area estimations determined for polyps within each of the experimental flumes 

are given in Table 1. Flume A contained ~10% more polyps than the other two flumes, with 

these polyps having a slightly greater diameter on average. 

2.3 Flume setup 

Three replicate recirculating flumes (Fig. 1) were set up in an 8 o C thermoconstant room. 

Each flume was of 58 litre volume and constructed primarily out of plexiglass, with a plastic 

return pipe fitted with a motor driven propeller to maintain recirculation. The flumes are 

described in detail in Berntsson et al. (2004). 

Fig. 1. Scale diagram of re-circulating plexiglass flume setup. For all experimental runs, three identical flumes 

were maintained. a) coral branches in plastic mount. b) direction of circulation. c) Artemia salina delivery point 

and location of sampling for A. salina concentration determination. d) motor. e) opaque plastic return pipe. 

The 45 coral pieces were randomised with 15 pieces placed in the test section of each 

flume. These fragments were arranged in rows in acrylic stands attached to the flume bases, 

with the broken ‘root’ of each fragment being carefully pushed into a 1cm silicone tube 

75

section drilled into the stand. The motor driven propeller in each flume was capable of 

maintaining a constant flow of up to 0.07 m s -1 . The same Lophelia pertusa fragments were 

maintained in each flume for all the experimental runs. 

2.4 Food characterisation 

Freshly hatched Artemia salina nauplii were used in the experimental runs. A. salina are a 

standard food source used in coral cultivation in the laboratory (Coles, 1969; Lasker, 1981; 

Dai & Lin, 1993;Houlbréque et al., 2004) and have been used at the Sven Loven centre for 

maintaining Lophelia pertusa for over 5 years. New cysts were hatched under standard 

conditions in an incubation aquarium. Following hatching, the concentration of Artemia salina 

was determined by taking five 1 ml subsamples from the incubation aquaria and filtering 

these onto 0.45 micron filter papers. The number of A. salina on each filter paper was 

counted under a dissecting microscope at 25x magnification, with an average count taken 

from the five subsamples. From this average the volume of water from the incubation 

chamber required to deliver a known quantity of A. salina to each of the experimental flumes 

could be determined. Food concentrations used in the experimental runs varied from 20,000 

to 100,000 A. salina individuals per flume, representing an A. salina density range of 345 - 

1725 Artemia l -1 . To assess the C and N concentration within freshly hatched nauplii 

triplicate 0.2 ml samples of freshly hatched A. salina were taken on two hatching days. The 

number of A. salina in each sample was counted on a glass slide under a dissecting 

microscope before the sample being analysed for total C and total N in a EURO EA 

Elemental Analyser after the method in Pike & Moran (1997). 

2.5 Experimental runs 

After transfer to the recirculating flumes, the coral fragments were maintained in the dark at 

8 o C for a week under a constant flow of 0.025 m s -1 to allow for acclimatisation. Every 24 

hrs during this period the water in each flume was replaced with fresh seawater pumped 

directly from the Kosterfjord by simultaneously siphoning out the old water and piping in new 

water. To ensure a significant changeover, this process was conducted for 30 mins in each 

flume with an inflow of ~3 l min -1 being maintained. During this acclimatisation week no food 

was delivered to the coral fragments until day 5, when each flume was given a moderate 

quantity of Artemia salina. Any food remaining after 24 hrs was removed by the siphoning 

process and additional filtering. 

76

Following the acclimatisation period the experimental runs commenced. For each run, a 

known concentration of Artemia salina nauplii was delivered to each flume as the food 

source. To assess whether flow was a factor in net capture rates, two flow speeds were 

used in this study, 0.025 m s -1 and 0.05 m s -1 , with both flow velocities comparable with 

those recorded regularly at both at the Tisler reef (Lavalaye et al., 2009) and the nearby 

Säcken Reef (Wisshak et al., 2005). In each experimental run an equal initial food 

concentration and flow speed were maintained across all three flumes. The Artemia salina 

food was delivered by large syringe directly into the flume water at 2 cm depth near the start 

of the flume return section (Fig. 1). 

After delivery of the food, the Artemia salina concentrations in suspension within each flume 

were monitored over a 24 hr period. Monitoring was conducted by taking triplicate 

subsamples of ~100 ml volume periodically from each flume (~2 – 8 hrs between samples). 

These samples were taken by siphoning out water directly from the flume from 2 cm depth 

(Fig. 1). A 1 cm diameter silicone hose was used for extraction with the open end facing into 

the direction of flow. After each subsample was taken its volume was determined and then 

filtered onto a 0.45 micron filter paper. The number of A. salina on each filter paper was 

counted under a dissecting microscope and the average A. salina concentration within each 

flume determined for each sampling time. 

The maximum net capture rate for each flume was defined as the slope of the concentration 

decrease of the Artemia salina concentration over the first 6 hrs of each experimental run. 

This figure was divided by polyps flume -1 (Table 1) to determine the maximum net capture 

rate polyp -1 . 

Table 1. Table showing the number of live Lophelia pertusa polyps, the average polyp diameters and buoyant 

weights of all branches used in each of the experimental flumes. 

Flume polyp Buoyant Total feeding Mean polyp Mean polyp Median Mode 

No. weight (g) area (mm 2 ) area (mm 2 ) / SD dia. (mm) / SD dia.(mm) dia. (mm) 

A 128 45 4338 37.5 / 11.3 6.5 6.0 7.0 

B 115 42 3398 33.5 / 12.2 6.2 6.0 7.0 

C 116 36 3539 34.8 / 20.6 5.9 5.0 7.0 

After each 24 hr experimental run the water in each flume was replaced with new piped 

seawater over a 30 minute period (see 2.4). A 63 micron sieve was then placed in each 

flume at the sampling position for 3 hrs to catch any remaining suspended Artemia salina. 

77

Each flume was then left undisturbed but under constant flow (the flow speed as used in the 

experiment) for 21 hrs prior to commencement of the next experimental run. 

Experimental runs were conducted at 0.025 and 0.05 m s -1 flow velocities, with Artemia 

salina densities of 345, 690, 1035, 1380 and 1725 A. salina l -1 . 

2.6 Control runs 

To ensure that any variation in Artemia salina concentration observed during experimental 

runs was not purely the result of the A. salina either becoming stuck within the coral 

structure or deposited somewhere within the flume, control runs were carried out following 

the live coral experimental runs. For these runs 15 dead coral fragments of comparable size 

to those used in the live experimental runs were placed in each flume in the same plastic 

mounts used previously. Control runs were carried out with flow velocities of 0.025 and 0.05 

m s -1 , with 1035 A. salina l -1 nauplii density. The A. salina concentration within each flume 

was monitored as during the live experimental runs (see 2.5). Data was treated similarly to 

the living coral treatments. 

2.7 Statistics 

All statistical analyses were carried out using the program SPSS v. 17.0. One-way ANOVA 

tests were used to determine whether maximum net capture rates in the initial 6 hours of 

each experimental run varied significantly with flow velocity or food concentration. One-way 

ANOVA tests were also carried out to see whether there was a significant difference in net 

capture rates between flumes containing dead corals and those containing live corals. All 

data was tested against a significance level of 0.05. In cases where the collected data did 

not meet the ANOVA test criteria of regular distribution or homogeneity of variance, the 

Kruskal-Wallis test was applied instead. Post-hoc testing for ANOVA tests was carried out 

using a LCD test, with a Mann-Whitney U test used for post-hoc analysis of Kruskal-Wallis 

test results. 

3 Results 

3.1 C and N concentration of Artemia salina nauplii 

Total C concentration found within each freshly hatched Artemia salina nauplii was 0.905 µg 

C A. salina nauplii -1 (SD=1.614 x 10 -2 ). Total N concentration was 0.175 µg N A. salina 

nauplii -1 (SD=3.696 x 10 -3 ). 

78

3.2 Maximum capture rate 

Net maximum capture rate ranged from 26.8 to 74.6 Artemia salina polyp -1 hr -1 at 0.025 m s - 

1 -1 -1 -1 

and from 8.7 to 27.1 A. salina polyp hr at 0.05 m s (Table 2). Control runs (with dead 

coral fragments in the flumes) showed negligible depletion of A. salina over the initial 6 

hours,

was made in food delivery to flume A, rendering the collected data meaningless and results 

are therefore only data from flumes B and C were used in the Kruskal-Wallis test. 

Comparisons between experiments conducted under 0.025 and 0.05 m s -1 flow velocities but 

with the same initial food concentrations showed significant differences in some instances. 

With an initial food concentration of 345 Artemia salina l -1 no significant difference was 

observed between maximum uptake rates at each of the two flow velocities (Kruskal-Wallis, 

χ² = 1.19, df=1, p=0.28). With an initial concentration of 690 A. salina l -1 a significant 

difference was observed between flow velocities (ANOVA, F(1,4)=34.25, p=0.004). No 

significant difference was observed between uptake rates under the two flow velocities in the 

experimental runs carried out with dead coral fragments (ANOVA, F(1,4)=25.2, p=0.67). 

3.3 Artemia salina removal over 24 hrs 

Artemia salina net capture over 24 hours was greater in the experimental flumes under flow 

velocities of 0.025 m s -1 than 0.05 m s -1 (Fig.2). A rapid reduction of >50% in A. salina 

concentration over the first 4-6 hrs under a flow velocity of 0.025 m s -1 was observed, 

followed by a slower rate of removal over the remainder of the 24 hrs, with a log curve best 

fitting the concentration data over time. Under a flow regime of 0.05 m s -1 this initial rapid 

removal was not observed. Under this higher flow velocity, an exponential curve best fits the 

concentration data observed across 24 hrs. Under 0.05 m s -1 flow, ~50% of the initial A. 

salina concentration was removed from suspension over the 24 hr period. Throughout all 

experimental runs live coral polyp tentacles were clearly deformed by water flow. The polyp 

tentacles were observed to be swept backward with the direction of water flow, and to a 

greater degree in runs carried out under 0.05 m s -1 flow velocity. 

Removal rates over 24 hrs were similar under 0.05 m s -1 flow for runs with initial 

concentrations of 690 and 1035 Artemia salina l -1 (Fig. 3). In these two runs a food 

concentration reduction of ~15 A. salina l -1 h -1 was observed, with the a slight, progressive 

reduction in this rate over time. A total reduction in concentration of between 350 and 400 A. 

salina l -1 was observed by the end of the 24hr runs given these initial food concentrations, 

across all replicate flumes. This rate of removal was not observed in runs with an initial 

concentration of 345 A. salina l -1 . Here the observed rate of removal was lower, at ~6-10 A. 

salina l -1 h -1 , again with this rate decreasing slightly over the 24 hrs (~150 A. salina l -1 

reduction over 24 hrs). 

80

Fig. 2. Artemia salina concentration over time in flume B during 4 experimental runs with initial concentration of 

1035 A. salina l -1 . Black squares represent 0.025 m s -1 flow and live coral , black triangles 0.05 m s -1 flow and live 

coral, white squares 0.05 m s -1 flow and live coral, white triangles 0.05 m s -1 flow and dead coral. Concentration 

curves were similar in each replicate flume. 

Fig. 3. Artemia salina concentration over time under 0.05 m s -1 flow in flume C. 3 experimental runs 

shown, with 345 (crosses), 690 (white triangles) and 1035 (black triangles) A. salina l -1 initial 

concentrations. Concentration curves were similar in each replicate flume. 

81

In runs carried out under 0.025 m s -1 flow and with initial concentrations of 1035 and 1380 

Artemia salina l -1 , a reduction of ~700 A. salina l -1 was observed over 24 hrs, with the 

majority of removal occurring in the first 4 hrs. In runs with initial concentrations of 690 and 

345 A. salina l -1 this reduction was not observed, and the concentration curves flatten out 

after a more moderate initial decrease during the first 4 hrs. 

4. Discussion 

4.1 Flow speed and capture rates 

Given that Lophelia pertusa is most commonly found in regions with at least periodically high 

bottom current velocities (Messing, et al., 1990; Thiem et al., 2006; White, 2007) it is 

interesting to observe in this study that the net capture rate of L. pertusa (given Artemia 

salina as food source) is greater under slower flow conditions. The experimental control runs 

show that entrapment of A. salina hydrodynamically within or against the not actively feeding 

coral framework is not a significant component of the net removal rate (Table 2, Fig. 2). 

Tsounis et al. (2010) observed the ability of L. pertusa to remove A. salina nauplii from 

suspension even when the polyp tentacles were partially retracted. This removal possibly 

explained by entrapment of A. salina within mucus produced by the live coral polyps, as 

observed in warm water corals (Sebens and Johnson, 1991). The swept back polyp 

tentacles observed in this study were still mucus covered and likely able to capture passing 

A. salina. The Tsounis et al. study was conducted using warmer water Mediterranean 

Lophelia pertusa specimens, a different experimental setup, higher A. salina concentration 

(~10 x the maximum concentration investigated in this study) and a lower flow velocity of 

~0.01 m s -1 than employed here, thus their results are not directly comparable. However, 

they reported a maximum capture rate of 284 A.salina polyp -1 hr -1 ( SD 130), ~4x the 

maximum capture rate observed in this study under 0.025 m s -1 flow. Since in this study 

increasing food density above 690 A. salina l -1 (under 0.025 m s -1 flow) little impact on 

maximum net uptake rates (Table 2, Fig. 4), it would seem more likely that the lower flow 

velocity used in the Tsounis et al. study would explain the larger maximum net capture rates 

they observed, rather than the greater food flux. Differences in metabolism between the 

north Atlantic and Mediterranean L. pertusa samples relating to seawater temperature 

(Dodds et al., 2007) would be a further possible explanation. 

82

Fig. 4. Artemia salina concentration over time under 0.025 m s -1 flow in flume A. 4 experimental runs shown, with 

345 (crosses), 690 (white triangles), 1035 (Black squares) and 1380 (black diamonds) A. salina l -1 initial 

concentrations. Concentration curves were similar in each replicate flume. 

From this study it is not possible to determine the degree to which Lophelia pertusa is 

removing Artemia salina from suspension by active feeding or by passive entrapment in 

surface mucus. Given the initial rapid removal rate followed by a slower removal rate 

observed under 0.025 m s -1 flow during runs with high initial A. salina densities (fig. 4) it 

would appear that passive mucus entrapment is unlikely to be the sole removal agent. It 

would appear that coral polyps gather food swiftly on initial food availability (start of 

experimental run), and reduce their capture effort after a time. 

A higher flow velocity can be expected to deliver a greater flux of food to the corals at any 

particular food density and thereby increase the encounter rate per surface area of feeding 

apparatus (Best, 1988). However, in this study, flow at 0.05 m s -1 was observed to deform 

the polyp tentacle arrangement to a greater degree than flow at 0.025 m s -1 , decreasing 

feeding surface area. The net effect may have been decreased encounter rates per polyp at 

the higher flow velocity. Such deformation in polyp tentacles above particular velocities has 

been observed a selection of soft corals (Fabricius et al.,1995), anemones (Anthony, 1997), 

gorgonians (Dai and Lin, 1993) and scleractinians (Sebens & Johnson, 1991), although in all 

these studies polyp tentacles are observed in extension under higher flow conditions than 

83

those employed here. Increasing flow velocity may also have reduced successful captures of 

A. salina by L. pertusa in two further ways. Firstly, adhesion to the polyp tentacles may be 

less likely in faster flow conditions and secondly, prey dislodgement following capture could 

potentially be more likely, as observed in octocorals (Wainwright and Koehl, 1976; 

Patterson, 1984; McFadden, 1986). To maintain active tentacle extension under increasing 

flow velocity increases respiration, therefore has an energy expenditure cost (Dai and Lin, 

1993), and presumably below some level of food availability or above a particular flow 

velocity it is no longer efficient for L. pertusa to maintain tentacle extension. 

This study indicates that potentially Lophelia pertusa, whilst requiring periodic fast current 

velocities to deliver fresh food to a reef and remove sedimentation may benefit from periods 

of low flow for increased prey capture. Such flow speed variations may be common at the 

majority of known L. pertusa reef sites (Davies et al., 2009) , and can clearly be seen in 

published records from the Tisler reef, the source of the corals used in this study (Lavaleye 

et al., 2009). It is however important to realize that the unidirectional, constant flow 

conditions employed in this flume study cannot be easily compared with current velocities 

and flow variations that polyps may be exposed to in the field. Within the complex 3D 

structure of a natural L. pertusa reef there will be many areas of reduced flow, as found in 

tropical reefs (Sebens et al.,1997), and within some dense coral thickets near stagnant 

diffusion dominated regions are likely develop (Kaandorp et al., 2005). 

4.2 Food concentration and capture rates 

Available Artemia salina concentration clearly has an impact on net capture rate, at least 

within the range of densities investigated. It was observed that at flow rates of 0.025 m s -1 

given an initial A. salina density of ≥ 1035 A. salina l -1 capture rates will reduce the available 

prey concentration by ~700 Artemia l -1 over 24 hrs, with the majority of this reduction 

occurring in the first 4 hrs (Fig.4). This could indicate that for the number of polyps used in 

these experiments that ~40000 A. salina nauplii (~340 A. salina polyp -1 ) are the maximum 

daily uptake, and that this amount of food could be captured swiftly given suitable flow 

conditions. Under 0.05 m s -1 flow velocity, capture rates are insufficiently high to allow the 

capture of this quantity of A. salina even with high food availability densities (Fig. 3). Under 

this flow velocity, only ~23000 A. salina nauplii were removed from suspension over 24 hrs 

(~196 A. salina polyp -1 ). At the lower food densities tested, this ~700 A. salina l -1 

concentration reduction could not be reached under either flow regime, with concentration 

levels observed to reduce more gradually over time (Figs. 3 & 4), indicating that at low 

84

densities net uptake is reduced by inability of Lophelia pertusa polyps to capture at 

maximum efficiency. 

4.3 Polyp size and net capture rate 

Flume A contained ~10% more polyps than flumes B and C. Polyp cup diameters within this 

flume tended to be slightly greater, and therefore feeding area overall was considerably 

larger (table 1), with the polyps likely to be on average older. Other cnidarians have been 

observed to capture food at a significantly slower rate as maximum organism growth size is 

approached (Medridium senile anemones, (Anthony, 1997)). Whether this is the case with 

scleractinians and Lophelia pertusa in particular is unknown, but it could account for the 

tendency in net capture rate observed to be slightly lower within flume A than in the other 

flumes during the majority of experimental runs (table 2), despite the greater polyp number 

and feeding surface area. 

4.4 Carbon capture 

Net capture rates determined in this study do not necessarily equal the number of Artemia 

salina nauplii successfully consumed by Lophelia pertusa polyps. They do however 

represent the removal from suspension of the A. salina nauplii and their delivery to the small 

flume 'reef' environment, by either direct consumption, entrapment within coral surface 

mucus or by weighing down the nauplii following contact with mucus. In the field such 

zooplankton would then provide input into the complex reef food web (van Weering et al., 

2003), most likely to be consumed and cycled by the suspension and filter-feeding reef 

associated organisms (Van Oevelen et al., 2009). Given the ~340 A. salina nauplii captured 

over 24 hrs polyp -1 under 0.025 m s -1 flow (see 4.2), this equates to ~307 µg C polyp d -1 . 

Provided suitable flow and prey density conditions, L. pertusa seems capable of acquiring 

this quantity within a few hours, as may be required in regions where food supply is periodic 

in quantity or variable in quality (Davies et al., 2009). 

Using the results from this study to estimate carbon delivery to reefs in the field by the 

actions of Lophelia pertusa would be difficult without knowledge of naturally occurring polyp 

densities and an understanding of the reef effect on flow velocity within and across a 

particular reef structure. 

85

4.5 Outlook 

Not investigated here is the role that density of polyps may have on net capture rates, a 

factor significant in other scleractinian reefs (Sebens et al., 1997). Assessing the ability of 

Lophelia pertusa to capture zooplankton of various sizes under differing flow velocities and 

the possible role colony size and morphology may have on this (Robinson et al., 2007) 

would be a useful next step in further developing our understanding of how this important 

reef building organism functions. 

5. Conclusion 

Within this study maximum net capture rates of Artemia salina by the coral Lophelia pertusa 

were observed to be significantly higher under 0.025 m s -1 than 0.05 m s -1 flow velocity. Net 

capture rates were reduced at prey densities below a particular threshold. The results from 

this work have immediate application in modelling L. pertusa reef ecosystems. 



CT-2005-511234) and is a CORAMM group collaboration. The Institute of Marine Research 

(IMR), Norway, is thanked for allowing the sampling of coral polyps from the Tisler Reef 

used in this study. T. Lündalv is gratefully acknowledged for piloting the ROV during the 

sampling stage of this work. We also thank L. Jonsson for assistance during sampling, A. 

Moje, H. Wagner and G. Mirelis for lab support. This is publication XXXXXXXXXXX of the 

Netherlands Institute of Ecology (NIOO-KNAW), Yerseke. 

References 

Anthony, K.R.N., 197. Prey capture by sea anemone Metridium senile (L.): Effects of body 

size, flow regime, and upstream neighbors. Biol. Bull. 192, 73-86. 

Berntsson, K. M., Jonsson, P.R., Larsson, A. I., Holdt, S., 2004. Rejection of unsuitable 

substrata as a potential driver of aggregated settlement in the barnacle Balanus improvisus. 

Mar. Ecol. Prog. Ser. 275, 199-210. 

Best, B.A., 1988. Passive suspension feeding in a sea pen: effects of ambient flow on 

volume flow rate and filtering efficiency. Biol. Bull. 175, 332-342. 

Coles, S.L., 1969. Quantitative Estimates of Feeding and Respiration for Three Scleractinian 

Corals. Limnol. Oceanogr. 14, 949-953. 

86

Costello, M., McCrea, M., Freiwald, A., Lundälv, T., Jonsson, L., Bett, B., Weering, T., Haas, 

H., Roberts, J., Allen, D., 2005. Role of cold-water Lophelia pertusa coral reefs as fish 

habitat in the NE Atlantic, Cold-Water Corals and Ecosystems, pp. 771-805. 

Dai, C.F., Lin, M.C., 1993. The effects of flow on feeding of three gorgonians from southern 

Taiwan. J. Exp. Mar. Biol. Ecol. 173, 57-69. 

Davies, A.J., Roberts, J.M., Hall-Spencer, J., 2007. Preserving deep-sea natural heritage: 

Emerging issues in offshore conservation and management. Biol. Conserv. 138, 299-312. 

Davies, A.J., Wisshak, M., Orr, J.C., Murray Roberts, J., 2008. Predicting suitable habitat for 

the cold-water coral Lophelia pertusa (Scleractinia). Deep Sea Res. Pt I. 55, 1048-1062. 

Davies, A.J., Duineveld, G.C.A., Lavaleye, M.S.S., Bergman, M.J.N., van Haren, H., 

Roberts, J. M., 2009. Downwelling and deep-water bottom currents as food supply 

mechanisms to the cold-water Lophelia pertusa (Scleractinia) at the Mingulay Reef complex. 

Limnol. Oceanogr. 54(2), 620-629. 

Davies, P.S., 1989. Short-term growth measurements of corals using an accurate buoyant 

weighing technique. Mar. Biol. 101, 389-395. 

De Mol, B., Van Rensbergen, P., Pillen, S., Van Herreweghe, K., Van Rooij, D., McDonnell, 

A., Huvenne, V., Ivanov, M., Swennen, R., Henriet, J.P., 2002. Large deep-water coral 

banks in the Porcupine Basin, southwest of Ireland. Mar. Geol. 188, 193-231. 

Dodds, L.A., Roberts, J.M., Taylor, A.C., Marubini, F., 2007. Metabolic tolerance of the coldwater 

coral Lophelia pertusa (Scleractinia) to temperature and dissolved oxygen change. J. 

Exp. Mar. Biol. Ecol. 349, 205-214. 

Dodds, L.A., Black, K.D., Orr, H., Roberts, J.M., 2009. Lipid biomarkers reveal geographical 

differences in food supply to the cold-water coral Lophelia pertusa (Scleractinia). Mar. Ecol. 

Prog. Ser. 397, 113-124. 

Dorschel, B., Hebbeln, D., Rüggeberg, A., Dullo, W.-C., Freiwald, A., 2005. Growth and 

erosion of a cold-water coral covered carbonate mound in the Northeast Atlantic during the 

Late Pleistocene and Holocene. Earth Planet SC. Lett. 233, 33-44. 

Dorschel, B., Hebbeln, D., Foubert, A., White, M., Wheeler, A.J., 2007. Hydrodynamics and 

cold-water coral facies distribution related to recent sedimentary processes at Galway 

Mound west of Ireland. Mar. Geol. 244, 184-195. 

Duineveld, G.C.A., Lavaleye, M.S.S., Berghuis, E.M., 2004. Particle flux and food supply to a 

seamount cold-water coral community (Galicia Bank, NW Spain). Mar. Ecol. Prog. Ser. 277, 

13-23. 

Fabricius, K.E., Genin, A., Benayahu, Y., 1995. Flow-Dependent Herbivory and Growth in 

Zooxanthellae-Free Soft Corals. Limnol. Oceanogr. 40, 1290-1301. 

Ferrier-Pagès, C., Witting, J., Tambutté, E., Sebens, K.P., 2003. Effect of natural 

zooplankton feeding on the tissue and skeletal growth of the scleractinian coral Stylophora 

pistillata. Coral Reefs 22, 229-240. 

Fosså, J.H., Mortensen, P.B., Furevik, D.M., 2002. The deep-water coral Lophelia pertusa in 

Norwegian waters: distribution and fishery impacts. Hydrobiologia 471, 1-12. 

87

Freiwald, A., Hühnerbach, V., Lindberg, B., Wilson, J.B., Campbell, J., 2002. The Sula Reef 

complex, Norwegian Shelf. Facies. 47, 179-200. 

Freiwald, A., Fosså, J.H., Grehan, A., Koslow, T., Roberts, J. M., 2004. Cold-water Coral 

Reefs. Cambridge, UK. 

Gass, S.E., Roberts, J. M., 2006. The occurrence of the cold-water coral Lophelia pertusa 

(Scleractinia) on oil and gas platforms in the North Sea: colony growth, recruitment and 

environmental controls on distribution. Marine Pollut. Bull. 52, 549-559. 

Hall-Spencer, J.M., Tasker, M., Soffker, M., Christiansen, S., Rogers, S., Campbell, M., 

Hoydal, K., 2009. Design of Marine Protected Areas on high seas and territorial waters of 

Rockall Bank. Mar. Ecol. Prog. Ser. 397, 305-308. 

Henry, L.A., Roberts, J.M., 2007. Biodiversity and ecological composition of macrobenthos 

on cold-water coral mounds and adjacent off-mound habitat in the bathyal Porcupine 

Seabight, NE Atlantic. Deep-Sea Res. Pt 1. 54, 654-672. 

Hii, Y.-S., Soo, C.-L., Liew, H.-C., 2009. Feeding of scleractinian coral, Galaxea fascicularis, 

on Artemia salina nauplii in captivity. Aquacult. Int.17, 363-376. 

Hirzel, A.H., Hausser, J., Chessel, D., Perrin, N., 2002. Ecological-niche factor analysis: How 

to compute habitat-suitability maps without absence data? Ecology 83, 2027-2036. 

Houlbreque, F., Tambutte, E., Allemand, D., Ferrier-Pages, C., 2004. Interactions between 

zooplankton feeding, photosynthesis and skeletal growth in the scleractinian coral 

Stylophora pistillata. J. Exp. Biol. 207, 1461-1469. 

Huvenne, V., Bailey, W., Shannon, P., Naeth, J., di Primio, R., Henriet, J., Horsfield, B., de 

Haas, H., Wheeler, A., Olu-Le Roy, K., 2007. The Magellan mound province in the 

Porcupine Basin. Int. J. Earth Sci. 96, 85-101. 

Jonsson, L.G., Nilsson, P.G., Floruta, F., Lundälv, T., 2004. Distributional patterns of macro- 

and megafauna associated with a reef of the cold-water coral Lophelia pertusa on the 

Swedish west coast. Mar. Ecol. Prog. Ser. 284, 163-171. 

Kaandorp, J.A., Sloot, P.M.A., Merks, R.M.H., Bak, R.P.M., Vermeij, M.J.A., Maier, C., 1995. 

Morphogenesis of the branching reef coral Madracis mirabilis. Proc. R. Soc. B. 272, 127- 

133. 

Kiriakoulakis, K., Fisher, E., Wolff, G.A., Freiwald, A., Grehan, A., Roberts, J.M., 2005. Lipids 

and nitrogen isotopes of two deep-water corals from the North-East Atlantic: initial results 

and implications for their nutrition. Cold-Water Corals and Ecosystems, pp. 715-729. 

Kiriakoulakis, K., Freiwald, A., Fisher, E., Wolff, G., 2007. Organic matter quality and supply 

to deep-water coral/mound systems of the NW European Continental Margin. Int. J. Earth 

Sci. 96, 159-170. 

Lasker, H., R., 1981. A comparison of the feeding abilities of three species of gorgonian soft 

coral. Mar. Ecol. Prog. Ser. 5, 61-67. 

Lavaleye, M., Duineveld, G., Lundälv, T., White, M., Guihen, D., Kiriakoulakis, K., Wolff, 

G.A., 2009. Cold-Water corals on the Tisler Reef. Oceanography. 22(1), 76-84. 

88

Lepland, A., Mortensen, P., 2008. Barite and barium in sediments and coral skeletons 

around the hydrocarbon exploration drilling site in the Træna Deep, Norwegian Sea. Environ. 

Geol. 56, 119-129. 

McFadden, C.S. 1986. Colony fission increases particle capture rates of a soft coral: 

advantages of being a small colony. J. Exp. Mar. Biol. Ecol. . 103, 1-20. 

Messing, C.G., Neuman, A.C., Lang, J.C., 1990. Biozonation of deep-water lithoherms and 

associated hardgrounds in the northeastern Straits of Florida. Palaios. 5, 15-33. 

Mikkelsen, N., Erlenkeuser, H., Killingley, J. S., Berger, W. H., 1982. Norwegian corals: 

radiocarbon and stable isotopes in Lophelia pertusa. Boreas. 11, 163-171. 

Mortensen, P.B., Rapp, H.T., 1998. Oxygen and carbon isotope ratios related to growth line 

patterns in the skeletons of Lophelia pertusa (L.) (Anthozoa, Scleractinia): implications for 

determining of linear extension rates. Sarsia. 83, 433-446. 

Mortensen, P.B., Hovland, M., Brattegard, T., Farestveit, R., 1995. Deep water bioherms 

ofthe scleractinian coral Lophelia pertusa (L.) at 64 o N on the Norwegian shelf: structure and 

associated megafauna. Sarsia. 80, 145-158. 

Mortensen, P.B., Hovland, M., Fosså, J.H., Furevik, D.M., 2001. Distribution, abundance and 

size of Lophelia pertusa coral reefs in mid-Norway in relation to seabed characteristics. J. 

Mar. Biol. Assoc. UK. 81, 581-597. 

Noé, S., Titschack, J., Freiwald, A., Dullo, W.-C., 2006. From sediment to rock: diagenetic 

processes of hardground formation in deep-water carbonate mounds of the NE Atlantic. 

Facies 52, 183-208. 

Orejas, C., Gori, A., Gili, J.M., 2008. Growth rates of live Lophelia pertusa and Madrepora 

oculata from the Mediterranean Sea maintained in aquaria. Coral Reefs 27, 255. 

Patterson, M.R., 1984. Patterns of prey capture in the soft coral Alcyonium siderium. Biol. 

Bull. 167, 613-629. 

Pike, S.M., Moran, S.B., 1997. Use of Poretics(R) 0.7 mu m pore size glass fiber filters for 

the determination of particulate organic carbon and nitrogen in seawater and freshwater. 

Mar. Chem. 57(3-4), 355-360. 

Purser, A., Bergmann, M., Lundälv, T., Ontrup J., Nattkemper, T., 2009. Use of machinelearning 

algorithms for the automated detection of cold-water coral habitats: a pilot study. 

Mar. Ecol. Prog. Ser. 397, 241-251. 

Riding, R., 2002. Structure and composition of organic reefs and carbonate mud mounds: 

concepts and categories. Earth-Sci. Rev. 58, 163-231. 

Roberts, J.M., Wheeler, A.J., Freiwald, A., 2006. Reefs of the Deep: The Biology and 

Geology of Cold-Water Coral Ecosystems. Science 312, 543-547. 

Roberts, J., Henry, L.A., Long, D., Hartley, J., 2008. Cold-water coral reef frameworks, 


north east Atlantic. Facies 54, 297-316. 

Roberts, J.M., Wheeler, A., Freiwald, A., Cairns, S., 2009. Cold-Water Corals. The Biology 

and Geology of Deep-Sea Coral Habitats. Cambridge, UK. 

89

Robinson, H.E., Finelli, C.M., Buskey, E.J., 2007. The turbulent life of copepods: effects of 

water flow over a coral reef on their ability to detect and evade predators. Mar. Ecol. Prog. 

Ser. 349, 171-181. 

Rogers, A.D., 1999. The biology of Lophelia pertusa (LINNAEUS 1758) and other deepwater 

reef-forming corals and impacts from human activities. Int. Rev. Hydrobiol. 84, 315- 

406. 

Rosenfeld, M., Bresler, V., Abelson, A., 2003. Sediment as a possible source of food for 

corals. Ecol. Lett. 2, 345-348. 

Sebens, K.P., Johnson, A.S., 1991. Effects of water movement on prey capture and 

distribution of reef corals. Hydrobiologia 226, 91-101. 

Sebens, K.P., Koehl, M.A.R., 1984. Predation on zooplankton by the benthic anthozoans 

Alcyonium siderium (Alcyonacea) and Metridium senile (Actiniaria) in the New England 

subtidal. Mar. Biol. 81, 255-271. 

Sebens, K.P., Vandersall, K.S., Savina, L.A., Graham, K.R., 1996. Zooplankton capture by 

two scleractinian corals,Madracis mirabilis and Montastrea cavernosa, in a field enclosure. 

Mar. Biol. 127, 303-317. 

Sebens, K.P., Witting, J., Helmuth, B., 1997. Effects of water flow and branch spacing on 

particle capture by the reef coral Madracis mirabilis (Duchassaing and Michelotti). J. Exp. 

Mar. Biol. Ecol. 211, 1-28. 

Thiem, Ø., Ravagnan, E., Fosså, J.H., Berntsen, J., 2006. Food supply mechanisms for 

cold-water corals along a continental shelf edge. J. Marine Syst. 60, 207-219. 

Tsounis, G., Orejas, C., Reynaud, S., Gili, J.M., Allemand, D., Ferrier-Pagès, C., 2010. Preycapture 

rates in four Mediterranean cold-water corals. Mar. Ecol. Prog. Ser. 398, 149-155. 

Van Oevelen, D., Duineveld, G., Lavaleye, M., Mienis, F., Soetaert, K., Heip, C.H.R., 2009. 

The cold-water coral community as a hot spot for carbon cycling on continental margins: A 

food-web analysis from Rockall Bank (northeast Atlantic). Limnol. Oceanogr. 54(6), 1829- 

1844. 

Van Weering, T.C.E., de Haas, H., de Stigter, H.C., Lykke-Andersen, H., Kouvaev, I., 2003. 

Structure and development of giant carbonate mounds at the SW and SE Rockall Trough 

margins, NE Atlantic Ocean. Mar. Geol. 198, 67-81. 

Wainwright, S.A., Koehl, M.A.R., 1976. The nature of flow and the reaction of benthic 

cnideria to it. In: Mackie, G.O. (Ed.), Coelenterate ecology and behaviour. Princeton 

University Press, Princeton, New Jersey, USA, 423 pp. 

Wilson, J.B., 1979. 'Patch' development of the deep-water coral Lophelia pertusa (L.) on 

Rockall Bank. Jour. Mar. Biol. Assoc. UK. 59, 165-177. 

White, M., 2007. Benthic dynamics at the carbonate mound regions of the Porcupine Sea 

Bight continental margin. Int. J. Earth Sci. 96, 1-9. 

90

Wisshak, M., Freiwald, A., Lundälv, T., Gektidis, M., 2005. The physical niche of the bathyal 

Lophelia pertusa in a non-bathyal setting: environmental controls and palaeoecological 

implications, Cold-Water Corals and Ecosystems, pp. 979-1001. 

Zibrowius, H., 1989. Taxonomy in ahermatypic scleractinian corals. Palaeontographica 

Americana 54, 80-85. 

91

Chapter 5 


(Scleractinia) following exposure to drill cuttings or resuspended 

sediments" 

Autun Purser 1,* , Ann I. Larsson 2 , Laurenz Thomsen 1 

Paper 4 

In preparation 


2 Department of Marine Ecology, University of Gothenburg, Tjärnö, SE-452 96 Strömstad, Sweden 

92

Abstract 

The Cold-Water Coral (CWC) Lophelia pertusa is the most significant framework building 

coral at the majority of CWC reef sites in European seas. Over the last ten years, the 

importance of these reefs as hotspots of biodiversity on the seafloor has become 

progressively more apparent. The high productivity often associated with the reef 

environments has led to considerable damage to reef structures by fishing practices over the 

years, and legislation protecting growing numbers of these reef structures from bottom 

trawling has been put in place in recent years. 

Although the immediate threat to reef structures by direct fishing damage has been reduced 

by the protective legislation, two possible anthropogenic threats to reefs have yet to be 

investigated in detail. Firstly, there is the potential hazard posed to reefs by increased 

particle exposure following the re-suspension of the seabed by trawling in close proximity to 

reef structures. Secondly, there is the possible hazard posed to reef structures by exposure 

to waste materials from the oil and gas industry – often active at depths and in regions of 

extensive coral growth. 

In this laboratory study Lophelia pertusa branches were placed in flow through aquaria and 

exposed to doses of particulate material. Doses of 6.6 and 66 mg cm -1 of both locally derived 

surface sediments and waste drilling material produced by the offshore industry were 

deposited onto the coral branches. Control aquariums were also maintained. Following 

exposure, the percentage of the exposed coral surface successfully cleared of material over 

24 hrs was measured. Additionally, the percentage of coral polyps extended following 

treatment was monitored over 96 hrs. In treated aquariums, ~70% of coral branches were 

free of settled material within 24 hrs. ~20% fewer extended polyp tentacles was observed in 

the treatment aquariums than in the controls, regardless of treatment particulate type or 

material concentration, for up to 48 hrs after exposure. 

The results of this investigation indicate that after exposure to settling particulate material, 

Lophelia pertusa can clear the majority of its surface efficiently. Also indicated is a moderate 

change in polyp behaviour following such exposure, although this change is short term. 

KEYWORDS: Lophelia pertusa, particulate exposure, drill cuttings, sediment cover, 

oil and gas industry. 

93

1. Introduction 

The cold-water scleractinian coral Lophelia pertusa is the most spatially widespread and 

structurally expansive of the reef building Cold-Water Corals (CWC's) in European waters 

(Roberts et al, 2009). The species is moderately slow growing (commonly observed ~1cm 

polyp extension yr -1 (Mortensen, 2001)), forming bushy, branched calcium carbonate 

structures with growth. These bushes eventually anastomose into larger reef structures 

given favourable conditions (Henry and Roberts, 2007). As an azooxanthellate species 

(Rogers, 1999), L. pertusa is not restricted in distribution to the photic zone, and has been 

found from 39m depth in Trondheimsfjord, Norway (Roberts, et al., 2009) down to 3383 m on 

the New England Seamount chain (Zibrowius, 1980). The most extensive reef structures are 

found at depths associated with the continental shelf and shelf margin, often in regions with 

enhanced flow velocities, such as seamounts (De Mol et al, 2002; Dorschel et al, 2007), 

fjords containing sills (Fosså et al, 2002; Fosså et al, 2005) or the shelf edge (Freiwald et al, 

2002). Whether L. pertusa is associated with such locations because the enhanced flow is 

required to remove sedimentation from the slow growing organism or because the flow rate 

provides a higher food flux (Duineveld et al, 2004; Kiriakoulakis et al, 2007; Thiem et al, 

2006; Dodds et al, 2009) is unclear. Both these factors, as well as others such as substrate 

suitability, temperature, or seawater density are likely involved in determining observed 

distribution patterns (Davies et al, 2008). 

The living Lophelia pertusa polyps on a developed reef form a thin living layer on top of a 

more expansive volume of dead calcium carbonate material. Often this area of live coverage 

is interspersed with cracks exposing the dead skeletal framework, or the coral favours 

growth in a particular direction (often into the direction of current flow) leaving a dead, 

exposed coral face behind (Fosså et al, 2004). These breaks in the living polyp layer and 

exposed, dead regions provide useful habitat niches for a number of sessile and motile 

benthic organisms (Roberts et al, 2008) and commercial fish species (Husebø et al. 2002). 

The size and angular structure of even moderately sized reef structures can have an 

influence on benthic flow conditions across the reef (White et al, 2007), again increasing 

habitat niche diversity. 

As understanding of the importance of Lophelia pertusa reefs as islands of elevated species 

richness on the continental seafloor has grown, concern for the protection of the reef 

environment has likewise increased. The association between commercial fish and reef 

94

structures has led to widespread degradation of CWC reefs throughout European waters 

(Fosså et al, 2002; Hall-spencer, 2009), the other side of the Atlantic (Reed et al, 2007), the 

Mediterranean (Orejas et al, 2009) and elsewhere through the action of bottom trawling 

(Fosså and Skjoldal, 2010) and long-line fishing (Orejas et al, 2009). In recent years a 

number of reef areas have been closed to bottom trawling via national legislation initiatives 

(Brock et al, 2009) and the direct threat posed by fishing reduced (Davies et al, 2007; 

Armstrong & van den Hove, 2008), although fishing with unlicensed or unmonitored vessels 

is ongoing in some areas (Hall Spencer et al, 2009). 

Even with the cessation of the direct threat to coral structure posed by bottom trawling, such 

activity in the vicinity of Lophelia pertusa reefs may cause a negative impact on reef health. 

Bottom-trawling commonly results in large-scale resuspension of bottom sediments 

(Palanques et al, 2001; Dellapenna et al, 2006) which can be transported, potentially into the 

reef environment, by benthic currents. The negative impact elevated particle exposure has 

on tropical scleractinian corals has been investigated in-situ and in the laboratory (Weber et 

al, 2006). In tropical corals, following coverage of the coral surface, anoxic conditions can 

rapidly develop leading to sulphate reducing bacterial damage to the coral, coral bleaching 

(Anthony and Fabricius, 2000) or smothering (Kelmo et al, 2003). Development of anoxic 

conditions and bacterial damage have not been observed in laboratory exposure studies 

carried out with L. pertusa (Allers et al, submitted), and as L. pertusa has no zooxanthellae 

partner, bleaching is not an issue. Smothering of L. pertusa could kill the coral if sufficient 

volume of material was deposited but given the complex three-dimensional branched 

structure of the coral this would be unlikely without a very large material input. 

The discovery of many Lophelia pertusa reefs within European waters has been made 

during exploration dives by the offshore oil and gas industry (Fosså et al, 2004). With many 

of the more extensive reefs located on the continental margin, at depths and in regions of 

interest and commercial use by this industry, there is concern that this industry my have a 

negative impact on CWC reef environments. The direct threat posed by drilling is minimal, 

with a spatially limited seabed region likely disturbed by the drilling operations (Jones et al, 

2006). As with fishing activity there could be the secondary threat posed to the reef 

environment by increased particle exposure, however – in this case from the sea 

sequestration of ‘drill cuttings'. Drill cuttings are the broken up bits of rock produced by the 

drilling operation, mixed with a selection of non-toxic chemicals, the lubricating ‘drilling mud’, 

required by the drilling process. During the drilling process the majority of these drill cuttings 

are brought to the surface and the drill rig before being released to the ocean after as much 

of the drilling mud as possible is removed from the cuttings and reused. At present, only drill 

95

cuttings produced using water-based drilling mud are released to the ocean in European 

waters. 

In this work we investigated whether exposure to elevated concentrations of particles 

impacts on the behaviour of Lophelia pertusa. Given the sensitivity of the L. pertusa reef 

environment and complexities of carrying out experimental work at depth, laboratory 

experiments were conducted. Given the sessile nature of L. pertusa, coral polyp tentacle 

activity was taken as a potential indicator of stress, as has been observed in tropical 

scleractinians and other cnidarians. The hypothesis under investigation was that exposure to 

a single pulse of a high concentration of either resuspended local sediments or drill cuttings 

would result in a period of tentacle retraction. Such a retraction, though not harmful to the 

coral in itself, would indicate a reduction in feeding activity, which could be significant if 

exposure events are repeated over time, as might be expected in areas close to regular 

trawling or throughout the ~4 weeks required for most commercial drilling operations. 

2. Material and Methods 

2.1 Lophelia pertusa polyp collection and preparation 

Lophelia pertusa polyps were collected for use in this study from the Tisler Reef, Norwegian 

Skagerrak in June 2008. The reef covers a section of a sill between the Tisler islands and 

the Norwegian mainland, an area of ~1200m by ~200m. The reef has been protected from 

bottom trawl fishing since 2003 (Lavalaye et al, 2009), but prior to this had suffered quite 

extensive trawl damage (Purser et al, 2009). Polyps were collected with a SPERRE 600 

Remote Operated Vehicle (ROV) from three large, trawl displaced coral blocks (table 1). 

Table 1. Depth, latitude and longitude of Lophelia pertusa coral blocks used in this study 

Coral block Collection depth (m) Latitude Longitude 

1 121 58 o 59 737 N 10 o 57 979 E 

2 115 58 o 59 759 N 10 o 57 971 E 

3 121 58 o 59 734 N 10 o 57 985 E 

Following collection, the Lophelia pertusa branches were transported to the Sven Loven 

Centre for Marine Research, Sweden and placed in 22 l flow-through aquaria in a 

96

temperature controlled laboratory (air temperature 7 o C, water temperature ~8 o C, pumped 

and sand-filtered from 40m depth in the Kosterfjord, approximately 10km from the Tisler 

reef) .The corals were fed daily on live Artemia salina nauplii under a flow regime of

a 

b 

Figure 1. Size distribution of particles used in coral exposures. Figure shows average concentrations of various 

size classes from 10 replicate readings. a) Drill cuttings. b) Local sediments. 

2.3 Experimental methodology 

All experimental work was conducted in a temperature controlled laboratory at the Sven 

Loven Centre for Marine Sciences, Gothenburg University, Strömstad, Sweden in July and 

August 2008. The laboratory was maintained with an air temperature of 7 o C and a piped 

supply of seawater from the Kosterfjord at a flow-through temperature of ~8 0 C. 

98

Two experimental runs were carried out in this work. From July 30th – 18 th August 2008 the 

first experimental run assessed polyp activity following exposure to two concentrations 

(66mg / cm -2 and 6.6mg / cm -2 ) of drill cutting fine fraction. The concentrations used are 

comparable with previous studies on warm water reef behaviour following particle exposure 

(Weber et al, 2006) and to the maximum deposition concentration guidelines used by the 

offshore industry. From August 19 th – August 23 rd 2008 polyp reactions to exposure to local 

sediment at the same concentrations was investigated. 

From July 30 th 2008 polyp activity was observed every 4 – 8 hrs in the 9 aquaria, with each 

rack of Lophelia pertusa branches photographed from above and every polyp on every 

branch examined individually. Each polyp was classified as being in one of three states – A) 

Extended, B) Visible or C) Retracted. Extended polyps have been identified to represent 

attempts at active feeding (Mortensen, 2001) or respiration (Dodds et al, 2007) in L. pertusa, 

and changes in the percentages of polyps carrying out these functions following exposure 

would indicate an impact on the coral. Figure 2 shows examples of the three states. Given 

that each aquarium contained a different number of polyps, the percentages of ‘extended’, 

‘visible’ and ‘retracted’ polyps were determined for each aquarium at each observation. 

‘Extended’ polyps were also noted as being ‘visible’ – i.e. a particular branch could have 

20% Extended polyps, 50% visible polyps and 50% retracted, with 40% of the visible polyps 

additionally being classified as extended. 

Figure 2. The three classifications of polyp activity used in this study. A) Fully extended polyps. B) Visible polyps. 

C) Retracted polyps. 

After 6 days of monitoring polyp activity in the 9 aquaria, the two concentrations of drill 

cutting material were each delivered to 3 aquaria by suspending the fine fraction in 200 ml of 

the laboratory piped seawater, then slowly pouring the suspension onto the surface water in 

each aquarium, attempting to homogenise distribution of material across the water surface. 

99

24 hrs after exposure, the majority of material delivered to the aquaria had settled and a low 

flow of seawater (

epeated measures designs. All analysis was carried out using SPSS 17.0 on a standard 

desktop PC. 

3. Results 

3.1 Percentage surface clearance 

The percentage of coral surface free from settled particulate material was similar following 

both particle type treatments. On average, ~70% of total coral surfaces in the high exposure 

dose treatment aquariums were clear of sedimentation. Standard deviations of ~25% 

indicate that clearance on individual branches could vary quite widely. Table 2 shows the 

clearance rate data from the local sediment treatment, with table 3 showing the data from 

the drill cutting treatment aquariums. 

3.2 Polyp activity 

Percentage of visible polyps 

Percentages of polyps classified as ‘visible’ did not vary significantly with treatment, 

treatment concentration or observation time, with 80% - 90% visible before and after 

treatment in all aquariums. 

Exposure to local sediments 

Percentages of polyps classified as ‘extended’ did differ significantly following treatment in 

some cases. Figure 3 shows the average percentages of extended polyps across the three 

aquariums for each treatment type. 

The repeated one-way ANOVA indicated no significant difference in average percentage of 

extended polyps before or after the delivery of treatments in the local sediment-free control 

aquariums (ANOVA, F(1,2)=1.77, p=0.315). 

Significant differences (ANOVA, F(1,2)=7.64, p=0.018) in extended polyp percentages prior 

and post exposure to the 6.6 mg cm -2 concentration of local sediments. LSD comparisons 

showed that during both the 0-48 hrs and 72-96 hrs post-treatment periods the percentages 

101

of exposed polyps differed from the pre-treatment period (p

103

104

Figure 3. Percentages of polyp activity found across the three replicate aquaria for the three concentration 

exposures to local sediments before and after exposure. Percentages shown for polyp activity in discreet time 

periods. (48 – 0 hrs before treatment, 0 – 48hrs after treatment, 48 – 72 hrs after treatment and 72 – 96 hrs after 

treatment). Averages based on between 4 and 12 separate polyp assessment periods. Error bars represent one 

standard deviation. * represents a significant difference (p

Figure 4. Percentages of polyp activity found across the three replicate aquaria for the three concentration 

exposures to drill cuttings before and after exposure. Percentages shown for polyp activity in discreet time 

periods. (48 – 0 hrs before treatment, 0 – 48hrs after treatment, 48 – 72 hrs after treatment and 72 – 96 hrs after 

treatment). Averages based on between 4 and 12 separate polyp assessment periods. Error bars represent one 

standard deviation. * represents a significant difference (p

was similar to that observed in the 6.6 mg cm -2 exposure aquariums (48-0 hrs pre treatment, 

M=45.5, 0-48 hrs post treatment, M=38.24, 48-72 hrs post-treatment, M=39.5, 72-96 hrs 

post-treatment, M= 41.0). 

4. Discussion 

4.1 Particle clearance rates 

As has been observed previously, Lophelia pertusa can be very successful in cleaning itself 

of settled particles swiftly (Mortensen, 2001). In this study ~70% of the L. pertusa exposed to 

particle settling was cleared within 24 hrs, for both particle types investigated here. The large 

standard deviations on this figure, and the low particle clearance observed from some 

fragments (tables 2 and 3) indicates that there is a degree of natural variation here. Although 

the coral fragments used in this study were as a homogenous selection as was available, 

variations in the life history of individual polyps or levels of damage to the coenosarc during 

collection could account for this variability in clearance rate. An additional cause could be 

branch orientation, with more horizontal regions of skeleton, or joints between branches, 

more likely to catch settling material mechanically. Lepland and Mortensen (2008) note that 

accumulations of barite associated with drilling operations can indeed accumulate in such 

structural features of L. pertusa following exposure to drill cuttings in suspension, and can 

remain within the calcium carbonate skeleton structure as polyp growth continues, calcifying 

over the deposited material. 

4.2 Polyp behaviour following exposure 

The moderately reduced percentage of polyp tentacles extended following the delivery of a 

pulse of particulate material represents only a minor behavioural change in polyp behaviour. 

For the two doses tested, concentration did not appear to be a significant factor in 

determining polyp response. Although in the case of local sediments, a significant reduction 

was only observed in the low concentration dose, and in the case of drill cuttings, the 

significant reaction was only observed in the high concentration dose, the average 

magnitude of extended polyp reductions was comparable (figures 3 and 4), with the large 

standard deviations observed rendering a treatment concentration for each particle type not 

significant. 

107

It is not surprising that Lophelia pertusa is resilient to particle exposure, given that it is often 

situated in regions where turbidity can often be high (Brooke et al, 2009; Davies et al, 2009; 

Lavaleye et al. 2009; Orejas 2009). Heightened deposition in areas of the reef structure, 

even with high prevailing current velocities is also likely, with the complex scleractinian reef 

structure often producing regions of low flow (Kaandorp et al, 2005; Appendix 1). Whether 

or not the energy cost to the organism in clearing settled material from the surface via mucus 

production is comparable with costs associated with buffeting by similar material in 

suspension is unknown. 

The local sediments were derived from the vicinity of a CWC reef, from a region actively 

trawled and probably reasonably representative (in terms of size classes and lability) of the 

type of material commonly resuspended by trawling close to the shallower reef sites, drill 

cuttings can be more variable in composition. Commonly, the bulk of material released into 

the ocean is from 12.25” drill sections, but within this work we have not investigated whether 

an alternative weighting agent or other variation in the chemical components of the drilling 

mud might not have elicited a more pronounced reaction from the Lophelia pertusa polyps. A 

great variation in particle size, colour, chemical composition and smell has been observed in 

drill cuttings produced from different depths of from the same well (Appendix 2), and 

therefore extrapolating the laboratory experimental run results to predict coral polyp 

behaviour after exposure to all released drill cuttings is not possible. 

4.3 Recommendations 

A useful follow up to this work would be to assess whether or not Lophelia pertusa polyps 

stay retracted for considerable periods if under constant exposure to particulate material. 

Palanques et al (2001) indicated heightened seabed turbidity for 5 days following trawling 

activity, and therefore trawling in the vicinity of a reef may cause such constant exposure. 

Likewise, drilling operations can last for up to a month, and so exposure to drill cutting 

concentrations, if released at a reasonably close proximity to the reef, could be near 

constant for such a period. 

108



CT-2005-511234) and is a CORAMM group collaboration. The Institute of Marine Research 

(IMR), Norway, is thanked for allowing the sampling of coral polyps from the Tisler Reef 

used in this study. T. Lündalv is gratefully acknowledged for piloting the ROV during the 

sampling stage of this work. We also thank L. Jonsson for assistance during sampling, H. 

Wagner and G. Mirelis for lab support. Katsia Pabortsava is thanked for assistance with 

particle size analysis. 

109

References 

Abramoff MD, Magelhaes PJ, Ram SJ (2004) Image processing with ImageJ. Biophotonics 

International 11(7): 36-42 

Armstrong CW, van den Hove S (2008) The formation of policy for the protection of coldwater 

coral off the coast of Norway. Mar Policy 32: 66-73 

Anthony KRN, Fabricius KE (2000) Shifting roles of heterotrophy and autotrophy in coral 

energetics under varying turbidity. J Exp Mar Biol Ecol 252: 221-253 

Brock R, English E, Kenchington E, Tasker M (2009) The alphabet soup that protects coldwater 

corals in the North Atlantic. Mar Ecol Prog Ser 397: 355-360 

Brooke SD, Holmes MW, Young CM (2009) Sediment tolerance of two different 

morphotypes of the deep-sea coral Lophelia pertusa from the Gulf of Mexico. Mar Ecol Prog 

Ser 390: 137-144 

Davies AJ, Duineveld GCA, Lavaleye MSS, Bergman MJN, Van Haren H, Roberts J M 

(2009). Downwelling and deep-water bottom currents as food supply mechanisms to the 


54(2): 620-629 

Davies AJ, Roberts JM, Hall-Spencer J (2007). Preserving deep-sea natural heritage: 

Emerging issues in offshore conservation and management. Biol Conserv 138: 299-312 

Dellapenna TM, Allison MA, Gill GA, Lehman RD, Warnken KW (2006) The impact of shrimp 

trawling and associated sediment resuspension in mud dominated, shallow estuaries. Estuar 

Coast Shelf S 69: 519-530 




Dodds LA, Roberts JM, Taylor AC, Marubini F (2007) Metabolic tolerance of the cold-water 

coral Lophelia pertusa (Scleractinia) to temperature and dissolved oxygen change. J Exp 

Mar Biol Ecol 349: 205-214 



Prog Ser 397: 113-124 

Dorschel B, Hebbeln D, Foubert A, White M, Wheeler AJ (2007) Hydrodynamics and coldwater 

coral facies distribution related to recent sedimentary processes at Galway Mound 

west of Ireland. Mar Geol 244: 184-195 

Duineveld GCA, Lavaleye MSS, Berghuis EM (2004) Particle flux and food supply to a 

seamount cold-water coral community (Galicia Bank, NW Spain). Mar Ecol Prog Ser 277: 

13-23 

Fosså JH, Skjoldal HR (2010) Conservation of Cold-Water Coral Reefs in Norway. In: 



110






Freiwald A, Hühnerbach V, Lindberg B, Wilson JB, Campbell J (2002) The Sula Reef 

complex, Norwegian Shelf. Facies 47: 179-200 

Hall-Spencer JM, Tasker M, Soffker M, Christiansen S, Rogers S, Campbell M, Hoydal K 

(2009) Design of Marine Protected Areas on high seas and territorial waters of Rockall Bank. 


Henry LA, Roberts JM (2007) Biodiversity and ecological composition of macrobenthos on 

cold-water coral mounds and adjacent off-mound habitat in the bathyal Porcupine Seabight, 

NE Atlantic. Deep Sea Res Pt I 54: 654-672 

Husebø A, Nøttestad L, Fosså JH, Furevik DM, Jørgensen SB (2002) Distribution and 

abundance of fish in deep-sea coral habitats. Hydrobiologica 471: 91-99 

Jones DOB, Hudson IR, Bett BJ (2006) Effects of physical disturbance on the cold-water 

megafaunal communities of the Faroe-Shetland Channel. Mar Ecol Prog Ser 319: 43-54 

Kaandorp JA, Sloot PMA, Merks RMH, Bak RPM, Vermeij MJA, Maier C (1995) 

Morphogenesis of the branching reef coral Madracis mirabilis. Proc R Soc B 272: 127-133 

Kelmo F, Attrill MJ, Jones MB (2003) Effects of the 1997-1998 El Nińo on the cnidarian 

community of a high turbidity coral reef system (northern Bahia, Brazil). Coral Reefs 22: 541- 

550 



96: 159-170 

Lavaleye M, Duineveld G, Lundälv T, White M, Guihen D, Kiriakoulakis K, Wolff GA (2009) 

Cold-Water corals on the Tisler Reef. Oceanography 22(1): 76-84 



56: 119-129 

Mortensen PB (2001) Aquarium observations on the deep-water coral Lophelia pertusa 

(L.,1758) (Scleractinia) and selected associated invertibrates. Ophelia 54: 83-104 

Orejas C, Gori A, Lo lacono C, Puig P, Gili JM, Dale MRT (2009) Cold-water corals in the 

Cap de Creus canyon, northwestern Mediterranean: spatial distribution, density and 

anthropogenic impact. Mar Ecol Prog Ser 397: 37-51 

Palanques A, Guillén J, Puig P (2001) Impact of bottom trawling on water turbidity and 

muddy sediment of an unfished continental shelf. Limnol Oceanogr 46: 1100-1110 

Purser A, Bergmann M, Lundälv T, Ontrup J, Nattkemper T (2009) Use of machine-learning 

algorithms for the automated detection of cold-water coral habitats: a pilot study. Mar Ecol 

Prog Ser 397: 241-251 

111

Reed JK, Koenig CC, Shepard AN (2007) Impacts of bottom trawling on a deep-water 

Oculina coral ecosystem off Florida. Bull Mar Sci 81: 481-496 

Roberts J, Henry LA, Long D, Hartley J (2008) Cold-water coral reef frameworks, 


north east Atlantic. Facies 54: 297-316 


Geology of Deep-Sea Coral Habitats. Cambridge, UK. 



Thiem Ø, Ravagnan E, Fosså JH, Berntsen J (2006) Food supply mechanisms for coldwater 

corals along a continental shelf edge. J Marine Syst 60: 207-219 

Weber M, Lott C, Fabricius KE (2006) Sedimentation stress in a scleractinian coral exposed 

to terrestrial and marine sediments with contrasting physical, organic and geochemical 

properties. J Exp Mar Biol Ecol 336: 18-32 



Zibrowius H (1980) Taxonomy in ahermatypic scleractinian corals. Palaeontographica 

Americana 54: 80-85 

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113

Chapter 6 

Summary & Future Plans 

114

Summary 

Within this thesis we present results from a selection of the work carried out by the 

CORAMM (Coral Risk Assessment, Monitoring and Modelling) project. The project had a 

broad research remit, with the overall aim being to improve both the level of understanding 

of the processes operating at Cold-Water Coral (CWC) ecosystems and also to gauge the 

level of risk posed to the ecosystem by various anthropogenic activities. CORAMM was 

envisioned from the outset to be a scientific project producing findings ideally of immediate 

usefulness to the oil and gas industry and regulatory authorities overseeing reef protection in 

CWC areas. 

In the first paper presented (chapter 2) we describe a wholly new method for investigating 

and / or monitoring the health status of Lophelia pertusa coral reefs. Within the CORAMM 

project we had the advantage of working with a diverse set of partners, with a great variety 

of skills and infrastructures available for collaborative use. In association with a biodata 

mining group from the University of Bielefeld we successfully developed a machine-learning 

system capable of identifying fauna on video still images. The main aim of the system was to 

quantify percentage seafloor coverage by living Lophelia pertusa corals. The system 

performed at a level of accuracy comparable to that achieved by a human using standard 

survey techniques. Crucially, the time taken for analysis was significantly less when using 

the new machine-learning method. 

The second paper (chapter 3) focused on assessing the degree to which a selection of 

faunal components of CWC reefs vary in abundance across and between reefs. Such 

information is important for the development of well thought out management plans, as if 

reefs are inhomogeneous in faunal composition, care must be taken to ensure protection of 

as diverse a selection of habitats and species assemblages as possible. In the paper we 

focus on eight key species, and track their distributions across three reef areas on the 

Norwegian Margin. We found that at particular reefs, substrate played the most significant 

role in determining relative abundance across reef. Between reefs, however, other factors 

must be at play, as we found great densities of some species on some reefs almost wholly 

or wholly absent from comparable substrate on other reefs - even spatially close reefs. One 

coral reef on the Norwegian margin is not necessarily much like another. 

The third paper in the thesis (chapter 4) presents findings from one of the numerous 

experimental investigations into the functioning of the scleractinian, structure building coral 

Lophelia pertusa carried out by CORAMM. In this paper we show experimentally that the 

115

coral captures zooplankton with considerably greater efficiency under unidirectional flow 

conditions of 0.025 m s -1 rather than 0.05 m s -1 . This was a surprising finding, as in the 

majority of literature the organism is described as requiring a high flow velocity to thrive. 

Possibly, a generally high flow to bring pulses of fresh material, remove sedimentation etc. is 

required periodically. Periodic occurrences of reduced flow (as might be associated with 

tides) could provide a window for the best utilisation by the coral of this fresh material. The 

findings in this paper also quantify the carbon uptake rates by coral polyps over a given 

period under varying flow conditions. This information is of great use in food web and 

dynamic energy budget modelling of the reef environment. 

The fourth paper in the thesis (chapter 5) also describes experimental work we carried out 

with Lophelia pertusa. In this case the work focused on the response of the coral polyp 

tentacles following exposure to different concentrations of particulate matter of various 

compositions was monitored. Additionally investigated was the degree to which the coral 

branches could clean themselves of particulate material in the absence of strong currents. 

We found that following exposure to high levels of resuspended local seabed particles or drill 

cutting waste material from the oil and gas industry (see 1.6.2) the percentage of polyps with 

their tentacles extended was reduced for a period up to ~72 hrs by ~20% following 

exposure. The degree to which this retraction is an indication of stress is uncertain, but 

certainly polyps with retracted tentacles are not actively feeding. Potentially, repeated 

exposure would use up the corals food reserves if the polyps never had the opportunity to 

actively feed, but this possibility was beyond the scope of the study presented here. We also 

observed that following the ~72hrs of retraction, a statistically significant greater percentage 

of polyps extended their tentacles than had prior to exposure, perhaps a stress response. 

We also report in chapter 4 that the majority of material settling on Lophelia pertusa 

branches (at least healthy branches collected from the Tisler reef, Norway), fails to remain 

settled on the coral, even under very moderate flow regimes. We propose that the curved 

structure of the coral makes coverage mechanically less likely that with flat, tropical 

scleractinian species. Mucus production clearly also played a role in cleaning of the coral 

surface, with the coenosarc covered skeleton regions freeing themselves almost wholly of 

sedimentary material very quickly after contact. 

Overall, within the papers in this thesis we take CWC coral research and monitoring 

strategies in some new directions, we challenge the paradigm that high flow velocities are 

required for food capture and demonstrate the resilience of the organism to short-term 

exposure to a selection of particulate materials at elevated concentrations. 

116

Future plans 

Although the CORAMM project officially ended in January 2010, a number of experimental 

investigations are in the process of being finalised and written up and we are actively 

involved in further developing useful video image assessment methods. 

Building on the successes with machine-learning presented in chapter 2, we are taking the 

system further to try and use it to address some interesting biological questions on species 

associations. ~10,000 images have been collected from two Norwegian margin reef 

locations by video sled. We are in the process of training the computer system to 

automatically identify, in addition to Lophelia pertusa, the gorgonians Paragorgia arborea 

and Primnoa resedaeformis, and the shrimps Pandalus sp. on these images. We are also 

training the system to identify substrates as either 'structure', 'rubble' or 'soft'. The aim of this 

study is for the first time to be able to assess accurately the degree to which small, mobile 

organisms (Pandalus sp.) tend to congregate in close proximity to the other species or 

substrate types. Such mobile organisms are always under sampled by box corers and grab 

samplers, and are difficult to accurately count using any but the most labour intensive video 

survey methods. By training the automated system to do so we will be able to process very 

large datasets swiftly. We are convinced of the usefulness of this approach, and see great 

promise in the first results of this new work. 

In addition to the collection of the video data used to assess species distribution patterns in 

chapter 3, a number of oceanographic measurements were also taken across the various 

studied reefs. Since completion of that study the dataset available has grown following 

further field work at other reefs. We are particularly interested in oxygen variation across reef 

sites, and are building up a collection of both opportunistic field data observations and 

planned time series datasets of dissolved oxygen concentration amongst reef structures. In 

the near future we would like to make a comparison between fauna, coral growth 

morphology, substrates and flow velocities within and outside the regions where we have 

observed these periodic oxygen reductions. 

The results presented in chapters 4 and 5 were preliminary investigations into coral feeding 

and reaction to exposure. We are currently finalising the last of a host of experiments 

investigating whether or not daily delivery of high sedimentary pulses (as might be expected 

in the vicinity of much bottom trawling resuspension or during the ~month of a drilling 

operation) negatively impacts on coral growth rates, feeding or causes mortalities. 

117


Lots of people made the completion of my PhD possible. I expect I have forgotten a host of 

important people. 

Primary thanks to: 

Rhianon Williams Putting up with me leaving a well paid job to 

mess about in Scandinavia and Germany 

Laurenz Thomsen Letting me carry out this PhD, giving me a lot 

of freedom of direction, not making me drive. 

Hannes Wagner, Annika Moje, Pedro de All the OceanLab people, for generally helping 

Jesus Mendez, Verena Klevenz, Vincent and not moaning when I broke stuff 

Rwehumbiza, Rosalyn Harrison, Sibila (well, Annika moaned but is thanked anyway). 

Pando, Handsome Geerd, Brian Alexander, 

Jule Marwick, Daniela Meißner, Maik 

Dressel, Michael Hofbauer,Stefan 

Baltrusch, Torsten Behnke, Volker Karpen, 

Rosa Garcia, Katsia Pabortsava, Serkan, 

Thomas Viergutz greatly, Texas Mike, 

plus transients... 

Ingunn Nilssen, Ingeborg Ronning, Ståle CORAMM partners 

Johnsen, Dick van Oevelen, Ann Larsson, 

Tim W Nattkemper, Dirk de Beer, Mathijs 

Smit, Frederick de Laender, Jörg Ontrup, 

Tomas Lundälv, Melanie Bergmann, 

Vikram Unnithan, Raeid Abed, Elke Allers 

Covadonga Orejas, Andrea Gori, Ruiju Further co-authors 

Tong, Laura Wehrmann, Tao Wang 

Andres Rüggeberg, Jan Helge Fosså, Thesis committee not previously thanked 

Jelle Bijma 

Tjarnö staff and students (Geno esp.) Lots of lab assistance (and equipment) 

STATOIL and IMR Funding and corals access 

Non-corals related Acknowledgements:- 

Leto and Loki Purser Williams Not drawing over ALL in prep manuscripts 

Pfanders, Tonia, Elgala’s, Michael, CIII For providing cheap accommodation etc. 

Keith and Mhaire Purser All sorts 

Other Pursers and McLeans Varying levels of 'support'... 

Other Williamses Ditto 

Sean Ames Software ‘assistance’ 

MTV transmission staff (Particularly Constant sarcasm 

Pete, Diane, Stu, Karl, Becky, 

Nick the Greek, Ward) 

Tristan, Staves, Mei, Bill, others Misc. 

118

Appendix 1 

Appendix 

Small scale flow conditions around reef structures 

Using the 10 m racetrack flume at Jacobs University Bremen, the flow conditions around a 

selection of dead coral fragments was investigated and mapped in three dimensions using a 

Nortek flow meter. A number of different flow speeds were utilised in the investigation, with 

data from a 5 cm s -1 run presented here. Behind the coral structures a distinct ‘wake effect’ 

was observed, regardless of the ambient flow speed of the flume water. In most runs, there 

was a net flow back towards the coral fragments downstream of the fragments in the bottom 

few cm of the water column, as shown in figures 1 and 2. 

Figure 1. Cross-sectional plot of benthic flow velocity in front and behind a Lophelia pertusa coral 

fragment placed in the centre of a 10m racetrack flume. Regions in green show flow back toward the 

coral fragment in its wake. The ambient flume flow velocity was 5 cm / s. Each cross represents a 

sampling point (approx 150). The red line indicates the rough outline of the coral fragment. 

119

Figure 2. Plan of benthic flow velocity in front and behind a Lophelia pertusa coral fragment placed in 

the centre of a 10m racetrack flume at 3cm above flume bed. Regions in green show flow back 

toward the coral fragment in its wake. The ambient flume flow velocity was 5 cm / s. Each cross 

represents a sampling point (approx 130). The red line indicates the rough outline of the coral 

fragment. 

120

Appendix 2 

Size variation within the 0 – 500 micron fraction of drill cuttings from the ‘Nona’ well 

(6407/2-5S) from the Heidrun field – drilled 12/8/09 

Using a Lazer In-Situ Scanning Transmissometer (LISST) the size fractions of material from 

2500 m – 2806 m drill depth drill cutting samples was analysed. Results from 15 samples 

from known depths are presented here. In all cases, drill cuttings were agitated for two hours 

and suspended in filtered water prior to sizing with the LISST instrument. The size 

distributions presented in the figures are based on 10 replicate sample runs within the 

LISST. Katsia Pabotsava is acknowledged for assistance with the LISST instrument and 

production of the presented size distribution graphs. 

% Total 

15.0 

10.0 

5.0 

0.0 

Particle size distribution DC 2500m (1) 

2.72 

3.2 

3.78 

4.46 

5.27 

6.21 

7.33 

8.65 

10.2 

12.1 

14.2 

16.8 

19.8 

23.4 

27.6 

32.5 

38.4 

45.3 

53.5 

63.1 

74.5 

87.9 

104 

122 

144 

170 

201 

237 

280 

331 

390 

460 

Median size, µm 

Figure 1. Size distribution from drill cuttings collected from drill depth of 2500m. 

% Total 

15 

10 

5 

0 


2.72 3.2 3.784.465.276.217.338.6510.2 12.114.216.8 19.823.427.632.538.445.353.563.174.587.9 104 122 144 170 201237280 331390 460 


psd, µm 


121

% Total 

15.0 

10.0 

5.0 

0.0 


2.72 

3.2 

3.78 

4.46 

5.27 

6.21 

7.33 

8.65 

10.2 

12.1 

14.2 

16.8 

19.8 

23.4 

27.6 

32.5 

38.4 

45.3 

53.5 

63.1 

74.5 

87.9 

104 

122 

144 

170 

201 

237 

280 

331 

390 

460 



% Total 

15.0 

10.0 

5.0 

0.0 


2.72 

3.2 

3.78 

4.46 

5.27 

6.21 

7.33 

8.65 

10.2 

12.1 

14.2 

16.8 

19.8 

23.4 

27.6 

32.5 

38.4 

45.3 

53.5 

63.1 

74.5 

87.9 

104 

122 

144 

170 

201 

237 

280 

331 

390 

460 



% Total 

15.0 

10.0 

5.0 

0.0 


2.72 

3.2 

3.78 

4.46 

5.27 

6.21 

7.33 

8.65 

10.2 

12.1 

14.2 

16.8 

19.8 

23.4 

27.6 

32.5 

38.4 

45.3 

53.5 

63.1 

74.5 

87.9 

104 

122 

144 

170 

201 

237 

280 

331 

390 

460 



122

% Total 

15.0 

10.0 

5.0 

0.0 


2.72 

3.2 

3.78 

4.46 

5.27 

6.21 

7.33 

8.65 

10.2 

12.1 

14.2 

16.8 

19.8 

23.4 

27.6 

32.5 

38.4 

45.3 

53.5 

63.1 

74.5 

87.9 

104 

122 

144 

170 

201 

237 

280 

331 

390 

460 



% Total 

15.0 

10.0 

5.0 

0.0 


2.72 

3.2 

3.78 

4.46 

5.27 

6.21 

7.33 

8.65 

10.2 

12.1 

14.2 

16.8 

19.8 

23.4 

27.6 

32.5 

38.4 

45.3 

53.5 

63.1 

74.5 

87.9 

104 

122 

144 

170 

201 

237 

280 

331 

390 

460 



% Total 

15.0 

10.0 

5.0 

0.0 


2.72 

3.2 

3.78 

4.46 

5.27 

6.21 

7.33 

8.65 

10.2 

12.1 

14.2 

16.8 

19.8 

23.4 

27.6 

32.5 

38.4 

45.3 

53.5 

63.1 

74.5 

87.9 

104 

122 

144 

170 

201 

237 

280 

331 

390 

460 



123

% Total 

15.0 

10.0 

5.0 

0.0 


2.72 

3.2 

3.78 

4.46 

5.27 

6.21 

7.33 

8.65 

10.2 

12.1 

14.2 

16.8 

19.8 

23.4 

27.6 

32.5 

38.4 

45.3 

53.5 

63.1 

74.5 

87.9 

104 

122 

144 

170 

201 

237 

280 

331 

390 

460 



% Total 

15.0 

10.0 

5.0 

0.0 


2.72 

3.2 

3.78 

4.46 

5.27 

6.21 

7.33 

8.65 

10.2 

12.1 

14.2 

16.8 

19.8 

23.4 

27.6 

32.5 

38.4 

45.3 

53.5 

63.1 

74.5 

87.9 

104 

122 

144 

170 

201 

237 

280 

331 

390 

460 



% Total 

15.0 

10.0 

5.0 

0.0 


2.72 

3.2 

3.78 

4.46 

5.27 

6.21 

7.33 

8.65 

10.2 

12.1 

14.2 

16.8 

19.8 

23.4 

27.6 

32.5 

38.4 

45.3 

53.5 

63.1 

74.5 

87.9 

104 

122 

144 

170 

201 

237 

280 

331 

390 

460 



124

% Total 

15.0 

10.0 

5.0 

0.0 


2.72 

3.2 

3.78 

4.46 

5.27 

6.21 

7.33 

8.65 

10.2 

12.1 

14.2 

16.8 

19.8 

23.4 

27.6 

32.5 

38.4 

45.3 

53.5 

63.1 

74.5 

87.9 

104 

122 

144 

170 

201 

237 

280 

331 

390 

460 



% Total 

15 

10 

5 

0 




% Total 

15 

10 

5 

0 


2.72 

3.2 

3.78 

4.46 

5.27 

6.21 

7.33 

8.65 

10.2 

12.1 

14.2 

16.8 

19.8 

23.4 

27.6 

32.5 

38.4 

45.3 

53.5 

63.1 

74.5 

87.9 

104 

122 

144 

170 

201 

237 

280 

331 

390 

460 



125

% Total 

15 

10 

5 

0 


2.72 

3.2 

3.78 

4.46 

5.27 

6.21 

7.33 

8.65 

10.2 

12.1 

14.2 

16.8 

19.8 

23.4 

27.6 

32.5 

38.4 

45.3 

53.5 

63.1 

74.5 

87.9 

104 

122 

144 

170 

201 

237 

280 

331 

390 

460 



Results summary 

These data show that there can be a large difference in particle size distributions 

within drill cuttings extracted from drill depths only a few meters apart. 

126

Cold-Water Corals. Distribution of fauna and ... - Jacobs University

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