Surface complexity enhances epibenthic biodiversity in a non-native oyster bed: Quantifying the response of benthic communities to the degradation of seabed complexity by bottom fishing gear
Stäbler, M. (2011). Surface complexity enhances epibenthic biodiversity in a non-native oyster bed: Quantifying the response of benthic communities to the degradation of seabed complexity by bottom fishing gear. MSc Thesis. School of Ocean Sciences, University of Wales-Bangor: Bangor. 22 pp.
Throughout numerous marine habitats, seabeds are ploughed by the gear of bottom fisheries. The damage this causes to emergent seabed organisms and physical structures like rocks and canyons leads to a decline of the bottom's complexity. Surface complexity has been associated with beneficial properties, such as provision of food and shelter from predation and water currents, and was found to enhance epibenthic biodiversity in several habitats. This study investigates how benthic biodiversity is expected to react to the loss of seabed complexity. It measures epibenthic species richness, abundance and biomass across a gradient of surface complexity in an intertidal, non-native oyster bed. By choosing Ostrea chilensis as a model organism, this study also contributes to the debate on the role of surface complexity in the effect of introduced species on native communities. The topography provided by the oyster shells was measured and digitized with a modified profile gauge and four indices of surface complexity were calculated from each profile. Epibenthic species richness and abundance increased linearly with all indices of complexity. This illustrates that through reducing the surface complexity of benthic habitats, bottom fishing can have a severe effect on epibenthic biodiversity. Through trophic relationships and recruitment, this can affect the targeted stock, and therefore needs to be considered in management plans. By showing the direct and indirect consequences of fishing on the habitat and how fisheries can benefit from healthier ecosystems, this study shows the advantages of an ecosystem approach to fisheries.
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