Sistemática e Evolução - Pôsteres - 29/11/2023 - 15:30 h às 16:30 h

Polychaetes are mostly marine annelids, which usually dominate benthic communities on soft and hard substrates, contributing to nutrient cycling and sediment aeration. In Brazil, 1343 species, 463 genera and 76 families of polychaetes have been recorded, of which 62 families are present along the coast of Rio de Janeiro state. The Cagarras Island Natural Monument is a no-take Marine Protected Area (MPA)- located from 4 to 8 km southward of the Ipanema beach. However, studies on the diversity of polychaetes in this MPA and its surrounding waters are still scarce. The present study aims to fill this knowledge gap. Sediment samples were recovered in seven stations between 11 and 40m depth in the vicinity of Redonda, Palmas and Comprida islands using a Van Veen grab on 14 February 2022. The samples were elutriated, sieved in a 0.5 mm mesh and fixed in ethanol 92.8% in the field. Specimens were sorted and identified under stereomicroscope. A total of 609 specimens were identified to 23 polychaete families. The families Syllidae Grube, 1850, Spionidae Grube, 1850, and Terebellidae Johnston, 1846 were the most abundant and widely distributed. Among these, Syllidae had a more uniform distribution, being the most abundant one in the majority of the stations, while the other two families had a high relative abundance in few stations. The relative abundance of the families contrasts with those observed for Guanabara Bay despite their proximity. These differences could be explained by contrasting environmental variables such as pollution, substrate, water flow and input of fresh water. These are preliminary results and future perspectives include finishing the identification of all samples and further analyses of the biodiversity.