ROLE OF BIVALVES IN CYCLING AND ... - Wageningen UR

ROLE OF BIVALVES IN CYCLING AND STORAGE OF NUTRIENTS:
FEEDBACKS FROM FILTER FEEDERS
Summary report of the WIAS minisymposium, June 4, 2012
FOR THE POWER POINT PRESENTATIONS GO TO :
www.imares.wur.nl/NL/onderzoek/aquacultuur/Produs/
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Mini symposium on June 4 th , 2012 in Wageningen, Zodiac, de Elst 1, 6708 WD Wageningen,
building 122, room C 85:
ROLE OF BIVALVES IN CYCLING AND STORAGE OF NUTRIENTS:
FEEDBACKS FROM FILTER FEEDERS
This symposium is organized by WIAS, the Aquaculture and Fisheries group (AFI) and the Institute of
Marine Resources and Ecosystem Studies (IMARES) of Wageningen UR, at the occasion of the PhD
defense of Henrice Jansen.
Program:
9.30 Welcome with coffee
9.40 Opening by symposium chair Dr Marc Verdegem, AFI-WUR
9.45 Introduction – prof dr Aad Smaal – AFI-WUR, Imares, NL
10.00 Nutrient regeneration by filter feeders – Ir Henrice Jansen – Imares, Yerseke, NL
10.20 Shellfish farming in low nutrient environments – Dr Ovind Strand – IMR, Bergen, Norway
10.40 Feedbacks of shellfish on nutrients and primary production - Dr Theo Prins, Deltares, NL
11.00 Coffee break
11.20 Filtration and biodeposition impacts of mussel seed on ecological carrying capacity - drs
Wouter van Broekhoven & ir Pascalle Jacobs, WUR and Imares Yerseke / Texel, NL
11.40 Nutrient extraction through mussel farming – Dr Jens Petersen, Shellfish Center,
Nykobing, Denmark
12.00 Extractive mussel aquaculture: balancing ecological good, services and impacts – Dr
Peter Cranford – Bedford Institute, Halifax, Canada
12.20 general discussion
12.45 closure
16.00 PhD defense of Henrice Jansen
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INTRODUCTION
Aad Smaal – AFI / Imares, WUR, NL; aad.smaal@wur.nl
See power point
CV
Aad Smaal is senior scientist at the Delta Department of the Institute of Marine Resources and Ecosystem
Studies (IMARES) in Yerseke, NL and he has a chair in sustainable shellfish culture at Wageningen
University. He started his carrier at the public works department, studying the impacts of the coastal
engineering Delta project on the ecology of the Oosterschelde and adjacent ecosystems. He has been
working in the field of ecology and bivalve aquaculture for over 30 years and has published over 50 peer
reviewed papers. He is member of the board of directors of the European Aquaculture Society
NUTRIENT REGENERATION BY FILTER FEEDERS
Henrice Jansen – Imares, Yerseke, NL, henrice.jansen@wur.nl
See power point
CV
Henrice Jansen has finished a PhD project at IMR Norway, studying the nutrient turnover by suspended
mussel communities in oligotrophic fjords, in the framework of the CANO project. Previously she worked
at Imares Ijmuiden in the field of aquaculture and aquatic ecology. She is now staff member of the
aquaculture department of Imares in Yerseke, NL working on IMTA and other projects.
SHELLFISH FARMING IN LOW NUTRIENT ENVIRONMENT.
Øivind Strand - IMR, Bergen, Norway, Ovind.strand@imr.no
Shellfish farming is typically found in coastal areas supplied nutrients from freshwater runoff and
upwelled deeper water supporting phytoplankton production. Still, a large fraction of the biogeographical
distribution of bivalves is in habitats characterized by oligo- to mesotrophic conditions. The water column
stratification in fjords derived from the freshwater input limits nutrient supply to the euphotic layers after
the spring blooms, creating oligotrophic conditions and low phytoplankton concentrations. This affects
shellfish farming in Norway and questions has been raised if the low nutrient environments is constraining
further development of the industry. I will present research on feeding behavior, food requirements for
growth, seston depletion, and enhancement through controlled upwelling of nutrient rich deep water, all of
relevance for demonstrating how shellfish farming can be maximized in such low nutrient environments.
CV
Øivind Strand is a Principal scientist at Institute of Marine Research in Bergen, Norway. He is a marine
biologist with research experience in bivalve ecology and aquaculture, with a focus on bivalveenvironment
interactions, scallop sea ranching and enhancement of carrying capacity of mussels by
controlled up-welling in fjords. He is also the leader of the CANO (-bivalve) project.
FEEDBACKS OF SHELLFISH ON NUTRIENTS AND PHYTOPLANKTON
Theo Prins, Deltares, PO Box 177, 2600 MH Delft, The Netherlands theo.prins@deltares.nl
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In many estuarine and coastal ecosystems, bivalve suspension feeders exert a strong grazing
pressure on the phytoplankton, resulting in a top-down control on phytoplankton and increased
nutrient cycling, a flux of nutrients from phytoplankton biomass to the sediment and the dissolved
inorganic nutrient pool, and shifts in phytoplankton composition.
The Oosterschelde (SW Netherlands) is an example of a coastal embayment with high stocks of
bivalve suspension feeders. Since 1990, external nutrient loading (N, P) to the Oosterschelde have
decreased significantly due to measures to reduce coastal eutrophication. As a consequence, the
relative importance of internal nutrient cycling in the Oosterschelde to sustain primary production
and phytoplankton biomass has increased. Monitoring data of nutrients, phytoplankton species
composition and biomass in the period 1990-2010 in the Oosterschelde were analyzed.
Developments in nutrients and phytoplankton were compared to trends observed in the coastal
waters of the North Sea, where the role of bivalve suspension feeders isless dominant. The effects
of bivalve suspension feeders on nutrient cycling and on phytoplankton in the Oosterschelde will
be discussed.
CV
Theo Prins is a marine ecologist who has been involved in basic and applied ecological research
and in management and policy advice for more than 25 years. He has a broad background in
estuarine and marine ecology, in field and experimental studies as well as in desk studies,
covering the ecological impacts of infrastructural works, eutrophication and other human
activities in estuarine and marine systems. He finished his PhD on the role of bivalves in estuarine
nutrient cycling in 1996.
FILTRATION AND BIODEPOSITION IMPACTS OF MUSSEL SEED ON ECOLOGICAL
CARRYING CAPACITY
Wouter van Broekhoven & Pascalle Jacobs, AFI/Imares, WUR, NL, wouter.vanbroekhoven@wur.nl
Impact of seed mussel collectors on carrying capacity through nutrient regeneration
Bivalves can be key mediators of nutrient circulation in aquatic ecosystems. Effects of bivalve aquaculture
on carrying capacity, defined here as the level at which an ecosystem is able to support a particular (group
of) species, may therefore be substantial. Bivalves may impair as well as stimulate carrying capacity as a
result of their control of nutrient circulation by affecting nutrient circulation and thereby primary
production. Primary production rates may be impaired by nutrient losses through harvest, denitrification
and burial. Conversely, stimulation may occur as nutrients are recycled to primary producers through direct
excretion or regeneration from waste products. Furthermore, nutrient stoichiometry may be changed if
nutrients are absorbed and released on unequal timescales or in unequal proportions. In this study we
estimate nutrient regeneration rates of seed mussels grown on Seed Mussel Collector (SMC) systems in the
Netherlands. Deployed at an increasingly large scale, SMCs provide substrate for Mytilus edulis spat
collection in macrotidal Dutch coastal systems. The summer period during which nutrient concentrations
are lowest partly coincides with the period of highest SMC biomass. To be able to estimate effects on
ecosystem functioning, we model mussel growth on SMCs using Dynamic Energy Budget modelling.
Uptake and excretion rates from intact SMC sections are measured under field conditions using a
mesoscale experiment. Furthermore, we define nutrient release from decomposing biodeposits because
little is known about the fate of solid mussel waste in macrotidal systems.
CV
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Wouter van Broekhoven is a marine ecologist (University of Groningen, Netherlands) with an interest in
anthropogenic controlling factors of ecological processes. After graduating he worked in shellfish ecology
during an exchange year at the National Institute of Environmental Studies of Japan. Then after two years
working in water and nature policy for the Dutch ministry of Water, he obtained a second MSc in
Conservation Science from Imperial College London. He is currently working on a PhD thesis at IMARES
investigating nutrient feedback processes of mussel seed.
Pascalle Jacobs
Impact of seed mussel collectors on plankton communities in tidal ecosystems
Bivalve grazing can have large effects on the carrying capacity of an area, due to both grazing and
excretion of waste products. Grazing is expected to negatively impact the food availability for both SMC
themselves as other filter feeders. Not only do bivalve cultures remove large amounts of phytoplankton,
due to low clearance rates of the smallest algae, a change in phytoplankton composition is expected. A
positive effect of mussel grazing might be the increased light penetration in the water, due to the removal
of both debris and phytoplankton. At times when the growth of the phytoplankton community is light
limited, grazing by mussels might increase the primary production. Another, less studied aspect of mussel
grazing, is the removal of micro zooplankton like ciliates and the potential effect of changes in the micro
zooplankton food web. In this study we focus on the effect of grazing by SMC seed mussels on the
plankton community. By means of incubation experiments using natural phytoplankton community in
mesocosms, clearance rates of both pico- and nanoplankton as well as micro zooplankton will be
established. After the incubation experiments, development of the phytoplankton community will be
monitored to investigate the recovery of the plankton community.
CV
Pascalle Jacobs started her PhD titled “Impact of seed mussel collectors on plankton communities in tidal
ecosystems” in 2010 under supervision of Roel Riegman. Previously she obtained a M.Sc. degree in
marine ecology and a M.Sc. in forest ecology. She worked as research assistant for the Universities of
Wageningen and Edinburgh, as junior policy employee at the Netherlands Organisation for Scientific
Research and as assistant press officer at Wageningen University and Research centre
NUTRIENT EXCTRACTION THROUGH MUSSEL FARMING
Jens Kjerulf Petersen, Danish Shellfish Centre, jkp@skaldyrcenter.dk
With the Water Framework Directive, goals have been set for water quality in coastal waters. In Denmark
have these goals been translated into reduction in loading of coastal waters with nutrients and in particular
with nitrogen (N). Much focus has been given to various means of reduction on land, e.g. by changing
agricultural practices, by establishing of wetlands in sensitive areas or by reducing animal husbandry or
use of artificial fertilizers.
An alternative or supplementary means of mitigation is by removing nutrients in the recipient. Mussel
farming has been suggested as a way of mitigating effects of eutrophication: a) harvesting the mussels will
remove nutrients; b) mussels will through their feeding mode improve water clarity and hence contribute to
the achievement of environmental goals; and c) mussels can also mitigate effects of internal sources in
coastal habitats. However, mitigation cultures have not yet been established in full scale and much of the
expected impact has been restricted to theoretical considerations.
A current Danish research project – Mussels, mitigation and feed for husbandry (MuMiHus) – has as aim
to study the potential of using mussels as a means of mitigating excess nutrient loading. The project has
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had a Danish standard size mussel farm (approx. 18 ha) producing at full scale as experimental platform.
The project has focussed on as well practical issues optimizing production volume as well as
environmental impact, ecosystem effects and management models. In this presentation, principal
considerations and first results of the MuMiHus are presented.
Jens Kjerulf Petersen is M.Sc. in marine biology from University of Copenhagen, Ph.D. from University
of Southern Denmark and is currently managing director at the Danish Shellfish Centre, an independent,
private research unit located in Nykobing Mors. JKP has specialised in estuarine ecology with special
focus on bentho-pelagic coupling, suspension feeder biology and ecology and shellfish production.
EXTRACTIVE MUSSEL AQUACULTURE: BALANCING ECOLOGICAL GOODS,
SERVICES AND IMPACTS.
Peter Cranford, Bedford Institute of Oceanography, Peter.Cranford@dfo-mpo.gc.ca
The ecological engineering concept of introducing bivalve aquaculture as a means of extracting
excess nutrients from coastal environments is derived from long-standing concepts on the
ecological benefits provided by natural bivalve populations. The capacity to provide these
services at both a commercial and environmental profit has added additional fuel to the rapid
development of the bivalve aquaculture industry. Case studies on the use of extensive/intensive
suspended mussel culture operations as biofilters to extract excess nutrients in coastal waters from
land-use (i.e. eutrophication bioremediation) and from fish culture (Integrated Multi-Trophic
Aquaculture) will be presented. The high complexity of aquaculture environment interactions will
be highlighted to illustrate the need to balance the beneficial aspects of nutrient extraction against
any concurrent ecological changes that could destabilize trophic pathways and nutrient dynamics.
The intensity of impacts from bivalve culture operations are always site-specific, owing largely to
local hydrodynamic conditions, and the goods and services provided will also vary with location.
The capacity to balance the goods, services and impacts associated with these ecological
engineering schemes is a fine art that will require an ecosystem-based approach and additional
research effort.
CV Peter Cranford is an oceanographer working for the Canadian government at the Bedford
Institute of Oceanography and is an Adjunct Professor with the Department of Oceanography at
Dalhousie University. His research specialties include bivalve physiological ecology and
aquaculture environment interactions.
General discussion with the speakers: O Strand, P. Cranford, T. Prins, J. Petersen & W. van Broekhoven
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