Revisited Syllidae of the coarse sand benthic communities from the English Channel
Résumé
Under the RESOMAR French Marine Laboratories framework, a Syllid course was organised in June 2015 at the Banyuls-surmer Marine Station to revisit the taxonomy and distribution of the Syllidae from the English Channel (EC), mainly for the current studies on the coarse sand community in the eastern part of the Channel. This habitat is one of the more extended in the EC and known as a favourable niche for the small polychaete fauna. A two year survey (winter and summer sampling periods) on 19 stations on the Branchiostoma lanceolatum coarse sand community offshore Dieppe-Le Tréport permit to identify 29 taxa including 26 species. Among them seven are new for the EC polychaete fauna and six other are sampled for the first time in the eastern part of the EC. Species richness and abundances show high seasonal variations with maximum in summer and minimum in winter. Shannon-Wiever diversity is estimated with and without identification of Syllidae to specific level showing the importance of high expertise level to express the diversity of such coarse sand habitat. Our results are compared with the historic data existing for the EC and the recent study of Olivier et al., (2011) of the intertidal coarse sand community from the Chausey Island western part of the EC. It appears that the Syllidae list recorded in Dauvin et al., (2003) need to be amended and the Syllidae diversity re-evaluated using recent taxonomic works. Today, at least, 90 species had been recorded for the whole English Channel.