Publication Abstract

PhD Thesis Examination: Aurelie Foveau, Universilty of Lille, Wimereux Marine Station, France

R. Coggan*

This study is devoted in providing an updated knowledge on the macrobenthic community structure and biodiversity in the eastern English Channel in the early 2000s. Results obtained were compared with results obtained by L. Cabioch and colleagues for the period of 1971-1976. The distribution of macrobenthic communities is highly governed by the sedimentary cover. The Folk classification was used for sedimentology and mapping of bottom type characterization for the two study periods. A relative stability of the sedimentary cover was observed wherein 69% of the study area showed slight or no change in sedimentary cover in the last 25 years. This is mainly due to the hydrodynamics in the area which is a dominant and structuring factor in the eastern English Channel. Variations were observed in bays, near the mouth of the estuaries and in the sand bank areas. The macrobenthic communities were studied separately for each period then compared. However, due to differences in methodologies applied for each period, considerable observations from comparative studies were difficult to detect. Geographical mapping results revealed that four entities or communities seemed recurrent in time depending on sediment type associations: (1) average sand; (2) coarse sand; (3) sandy gravel and (4) pebbles. Analysis done on two latter sediment types showed that the various geographical entities constituting associated communities are distinct at the scale of the eastern English Channel. Species diversity, abundance and richness are significant with 875 taxa identified from 318 sampled sites, where the latter is still considered underestimated. Finally, statistical methods were applied to modeling and prediction of potential habitats of 22 benthic invertebrates. Habitat modeling results obtained are in accordance with field observations and showed that for the majority of considered species (average and fine sand-associated species excluded) occupy their suitable niches/habitat.