The Role of Kelp in the Marine Environment - National Parks ...

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Table 3 Primary production as tonnes of carbon in Strangford Lough. Intertidal macroalgae Subtidal macroalgae Intertidal Sub-tidal 10m TOTAL 24,098 24,098 68,582 68,582 Phytoplankton 812 5,952 3,394 10,158 F. The fate of kelp production It is agreed that little kelp production is grazed directly but enters the food chain as detritus (e.g., Mann, 1988). The Blue Rayed Limpet grazes kelp and is known to cause some older plants to detatch by weakening the holdfast but in general little of the living plant is consumed. This may reflect the low nitrogen content of macroalgae. Phytoplankton differs from kelp in their C:N ratios. Plankton typically has a ratio of 106:16:1 C:N:P but Laminaria is recorded as 239:13:1 and 384:25:1. That is, Laminaria tissue is deficient in N and P compared to plankton and consequently is less nutritious for consumers. Laminaria detritus can be consumed directly or colonized by bacteria which use the material as an energy source and absorb inorganic N to form protein. In turn, the bacteria-detritus aggregate can be consumed by invertebrates. However, some mussel species can digest kelp detritus directly. An interesting result is that only 23% of kelp detritus carbon was available to invertebrate filter feeders (the rest was metabolized by the bacteria) but nearly all the N from the kelp was available. This suggests that nitrogenous compounds limited the ecosystem rather than energy stored in carbohydrate. It also suggests that comparisons based solely on carbon production may overestimate the value of kelp as a food source relative to phytoplankton. A second pathway to invertebrate consumers lies in the flocculation or formation of particulate organic carbon (POC) from DOC that is then colonized and metabolized by bacteria. As DOC can constitute a substantial proportion of kelp production, this pathway may be of importance to higher trophic levels. 25
Several studies have demonstrated the importance of kelp as a food source. Duggins (1989) in a study of kelp beds in the Aletutian Islands found that 40 – 60 % of carbon found in coastal invertebrates could be traced to kelp photosynthesis. Fredrikson (2003) also showed that kelp (L. hyperborea) carbon was incorporated into invertebrates and birds off Norway. Indirect evidence also shows the importance of kelp in coastal ecosystems. Duggins et al. (op. cit.) showed that filter feeders grew considerably slower off islands where the kelp forest had been destroyed by sea urchins. Dugan et al. (2003) showed that biodiversity of birds and invertebrates on sandy Californian beaches could be correlated with the quantity of drift kelp washed ashore and left to decay. As the total removal of the kelp forest not only removes it’s contribution to primary production but also destroys the habitat of many of the species which live on this production, it is difficult to separate the effect of removing a food source from that of destroying a habitat. But as kelp primary production does not accumulate in the ecosystem and it is so intense relative to normal planktonic production, it is reasonable to assume that much of it is consumed by other species. This assumption is supported by the studies noted above. 2. Available Substratum A. Flora All parts of kelps (holdfast, stipe and blade) function as substrata, and with increasing age of kelp plants the number of both individuals and species of kelp associated flora increases significantly (Rinde et al., 1992). The epiphytic flora, generally found on the stipes of Laminaria hyperborea, comprises mainly red algal species, such as Palmaria palmata, Phyllophora spp. and Delesseria sanguinea (Whittick 1983). Along with these leafy species, a substantial number of filamentous, branched species, such as Polysiphonia and Ceramium species, and coralline encrusting algae, such as Lithothamnion spp., can also be found. No peer-reviewed studies have been carried out in Ireland on the epiflora specifically associated with kelp even though its physical structure provides a perfect and convenient sampling unit that can be aged and measured with some degree of 26
Page 1: The Role of Kelp in the Marine Envi
Page 4 and 5: Details of Contributors Birds Fish
Page 6 and 7: Executive Summary Kelp forests have
Page 8 and 9: Birds Acknowledgements Professor R.
Page 10 and 11: Introduction Kelp species represent
Page 12 and 13: Each year the kelp plant renews its
Page 14 and 15: estimate (Birkett et al., 1998) of
Page 16 and 17: Other researchers have highlighted
Page 18 and 19: Figure 2 δ 13 C values from the di
Page 20 and 21: kelp population was estimated by Ar
Page 22 and 23: Figure 4 Growth in length of the la
Page 24 and 25: varies with the age of the plants.
Page 28 and 29: accuracy. Most epiphytic algae are
Page 30 and 31: collected off the Cumbrian coast ri
Page 32 and 33: Lavery et al. (1999) and Dugan et a
Page 34 and 35: (op. cit.) and Lorentsen et al. (op
Page 36 and 37: Laridae (Gulls) e.g., Herring Gull
Page 38 and 39: Interesting studies of the interact
Page 40 and 41: 1985). These birds prey upon e.g. b
Page 42 and 43: as amphipods and crabs beneath. Pur
Page 44 and 45: An interesting and indirect interac
Page 46 and 47: 5-8% lower than velocities above th
Page 48 and 49: Methods of Kelp Harvesting Impact R
Page 50 and 51: Scale of kelp removal It is self ev
Page 52 and 53: Blade cutting vs. complete plant re
Page 54 and 55: � fallow years, as successfully p
Page 56 and 57: trophic and habitat associations (N
Page 58 and 59: Foreman (1984) noted that if sustai
Page 60 and 61: variability in benthic community st
Page 62 and 63: lock was occupied by laminarians an
Page 64 and 65: Laminaria hyperborea (Gunn.) Foslie
Page 66 and 67: Pylophora crispa, 1% Ceramium nodul
Page 68 and 69: Most species on L. digitata were en
Page 70 and 71: after 3 days exposure in September
Page 72 and 73: many species have planktonic larvae
Page 74 and 75: decline in juvenile rockfishe, i.e.
Page 76 and 77:
Species classified as threatened or
Page 78 and 79:
The conservation status of bird spe
Page 80 and 81:
Production Future Research Nearly a
Page 82 and 83:
� Biomass and standing stock surv
Page 84 and 85:
legislative obligations in relation
Page 86 and 87:
Conclusions Even well managed kelp
Page 88 and 89:
waters and with the postulated rise
Page 90 and 91:
Arzel, P. (1998). Les laminaires su
Page 92 and 93:
Bustamante, R. H. & Branch, G. M. (
Page 94 and 95:
Christie, H., Jorgensen, N.M., Nord
Page 96 and 97:
Deady, S. and Fives, J.M. (1995b).
Page 98 and 99:
ecosystems. Bulletin of Marine Scie
Page 100 and 101:
Graham, M. H. (2002). Prolonged rep
Page 102 and 103:
Kain, J. M. (1977). The Biology of
Page 104 and 105:
Mann, K. H. (1988). Production and
Page 106 and 107:
Nicholson, N.L. (1970). Field studi
Page 108 and 109:
Quast, J. C. (1968a). Fish fauna of
Page 110 and 111:
Sellers, R. M. (2004). The Great Co
Page 112 and 113:
Swaby, S.E. and Potts, G.W. (1990).
Page 114 and 115:
Went, A. E. J. (1957). List of Iris
Page 116 and 117:
Appendix 2 Macroinvertebrate specie
Page 118 and 119:
Gibbula umbilicalis Helcion pelluci
Page 120 and 121:
Appendix 3 Description of habitat,
Page 122 and 123:
Appendix 3 continued Anguilla angui
Page 124:
Appendix 4 Conservation status of b
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