Anthropogenic impact of oyster farming on macrofauna biodiversity in an eelgrass (Zostera marina) ecosystem of the English Channel

Abstract Zostera marina flourish along the west coast of Cotentin, in cohabitation with extensive oyster cultivation. In 2016, seasonal sampling was carried out based on five combinations of conditions involving vegetated and unvegetated areas, presence or absence of oyster tables and a control station without either eelgrass or oyster cultivation. The sediments consisted of muddy sandy gravel and no significant difference of sediment composition was observed between stations and seasons. A total of 147 taxa and 8404 individuals were recorded over a period of the one year with a sampling effort of 5 m 2 . The effects of oyster farming are relatively limited, and are not a handicap for the extension of Zostera meadows in this part of the English Channel. Nevertheless, low Taxonomic Richness and abundances characterize the tractor pathway. Macrofauna abundances, biomasses and number of eelgrass shoots are similar to those reported at other sites in the English Channel and from the North-eastern Atlantic.