Can low sea urchin densities control macro-epiphytic biomass in a north-east Atlantic maerl bed ecosystem (Bay of Brest, Brittany, France)?
The distribution, abundance and feeding behaviour of sea urchins ( Paracentrotus lividus, Psammechinus miliaris, Sphaerechinus granularis ) and the macro-algal biomass were assessed in two maerl beds within a north-east Atlantic coastal ecosystem (Bay of Brest, Brittany, France). To study the possib...
| Published in: | Journal of the Marine Biological Association of the United Kingdom |
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| Main Authors: | , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Cambridge University Press (CUP)
2002
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| Subjects: | |
| Online Access: | http://dx.doi.org/10.1017/s0025315402006276 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0025315402006276 |
| Summary: | The distribution, abundance and feeding behaviour of sea urchins ( Paracentrotus lividus, Psammechinus miliaris, Sphaerechinus granularis ) and the macro-algal biomass were assessed in two maerl beds within a north-east Atlantic coastal ecosystem (Bay of Brest, Brittany, France). To study the possible control of herbivorous sea urchins on the macrophytic algae, one maerl bed under the influence of urban sewage (northern site) was compared to one less influenced by urban and industrial outlets (southern site). Macrophytic biomass in the northern site was estimated as 40-fold higher than in the southern site where sea urchins were, on average, 38-times more numerous. Preliminary results support the hypothesis that grazing of sea urchin, even in low densities, can be a factor regulating the macrophytic biomass on maerl beds except in too nutrient enriched environments. So in the northern basin of the Bay, data pointed out the role of anthropogenic impacts on macrophytic biomass increase which was concomitant with the progressive disappearance of sensitive herbivorous species like sea urchins, both processes result in change in the ecosystem. |
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