Polychaetes associated with seagrass meadows, Posidonia oceanica at Salloum Marine Protected Area, Mediterranean Sea, Egypt

Posidonia oceanic meadows are one of the most important subtidal communities in the Mediterranean Sea and are very rich in micro and macrofauna. The present study investigated the associated polychaetes with P. oceanica from Salloum Marine Protected Area that extends along the northwestern coast of the Egyptian Mediterranean Sea from autumn 2018 to summer 2019. A total of 37 species of polychaete species were recorded, within 33 genera belonging to 18 families and 6 orders. Order Phylloida was the dominant, represented by 14 species (37.84 % of all species) within 11 genera and 6 families (33.33% of all families). It was followed by orders Eunicida and Terebellida; each was represented by 4 families and 7 species. The results showed that families Nereididae, Syllidae, Serpulidae, and Terebellidae were dominant; each comprised four species and were represented together by 16 species of 43.24 % of all recorded polychaetes. Out of the recorded species, 30 were recorded at sites S1 and S2, declined into 19 and 17 species at S3 and S8, respectively. The abundance of collected polychaetes showed spatial and seasonal fluctuations. A total of 879 individuals of recorded species were obtained. The highest number of individuals was 352 (40.05 %), collected at S1 and declined to 295 at S2 and reached the lowest (117 and 115 individuals) at S3 and S8, respectively. Seasonally, winter had the highest number of individuals (283) and declined sharply to 144 individuals in autumn. These results showed that sites S1 and S2 were characterized by the highest number of species and individuals than the eastern sites, S3 and S8. Thus, there are 31 infaunal species, living either in permanent burrows or temporarily buried in the soft bottom around seagrasses compared with only 6 sessile or sedentary species, living attached to or fixed on P. oceanica parts.