First Investigation of the Composition and Spatial Distribution of Polychaete Feeding Guilds from Essaouira Protected Coastal area (Atlantic Coast of Morocco)

Several researches have been conducted to explain patterns of the abundance, richness and taxonomic diversity of benthic polychaetes; however, such analyses have ignored the functional diversity of polychaete communities, especially feeding guilds in intertidal rocky shores. The present study was carried out to describe and analyse the polychaete feeding guilds on intertidal rocky shores and then examine the effects of environmental factors. Twelve intertidal rocky shores from the coastal protected area of Essaouira (Atlantic coast of Morocco) were sampled during the summer of 2016. A total of 42 polychaete species belonging to 29 genera and 16 families were identified among the 4517 specimens collected. The medium biomass per sampling site was found to be 37.61 ± 15.80 g.m-2 . The polychaete species were classified into five feeding guilds, and nine feeding modes. The filter feeders were the dominant feeding guild (32%) followed by omnivores (23%), burrowers (20%), carnivorous (15%) and surface deposit-feeders (10%). The FDT (filter feeder, discretely motile, with tentacles) was the most abundant feeding mode, accounting for 24% of abundance (mainly represented by Sabellaria alveolata), followed by the ODJ feeding mode (omnivorous, discretely motile, with jaw apparatus) with 22%, and the SDT feeding mode (surface deposit feeder, discretely motile, with tentacles) with 18.9%. The highest trophic importance index and index of trophic diversity values were recorded in the southern region of Essaouira coastline. Based on the canonical correspondence analysis, composition and spatial distribution of polychaete feeding guilds were mainly related to the length of rocky shores and water temperature

Spatial and temporal assessment of metals contamination in the surface sediments of biogenic intertidal reefs of Sabellaria alveolata (Annelida: Polychaeta) from Essaouira protected coastal area (Atlantic coast of Morocco)

In the present study, we assessed the spatial and temporal distributions of metal contents and their environmental risks in the surface sediments from Essaouira protected coastal area (Atlantic coast of Morocco). Surface sediment samples of the biogenic reefs of Sabellaria alveolata (Annelida: Polychaeta) were collected seasonally, and the fine fraction ( Fe > Zn > Cr > Cu > Pb > Cd. Concentrations were lower than mean Earth crustal contents and world average background levels except for Cd. Spatial and temporal variations of metals were highly significant, and largely determined by geochemical background properties and inputs of terrigenous material except for Cd which was associated with upwelling phenomena. Comparison with sediment quality guidelines (SQGs) and ecotoxicological values indicated few exceedances with regard to most metals except for Cd, Cr and Cu. Consequently, the dredged sediment may be dumped at sea with little likelihood of adverse biological effects. However, some sediments had a moderately high Cd content, especially during summer and warrant more detailed assessment