MARINE QUALITY ASSESSEMENT OF AMAZON MANGROVES USING BENTHIC AND DIVERSITY INDICES BASED ON POLYCHAETE FAUNA

The aim of this study was to evaluate the impact of environmental disturbances in two mangroves in the Gulf of Maranhão, Brazil, based on the composition of polychaete communities. We collected samples from two sites: Buenos Aires stream, which is located near the Port of Itaqui, and Quebra Pote. We collected samples from three different zones at each site to evaluate possible gradients of environmental disturbance. We used biotic indices (AMBI, M-AMBI, BENTIX) and diversity indices to assess the level of disturbance. We found 731 specimens of polychaetes belonging to 11 families. The highest polychaete abundance occurred when there was a period of lower salinity in March 2014. The species Paraonis sp. and Syllis sp. were the most abundant. Further analysis of these indices revealed there were likely different sources of environmental disturbance between the two study sites. We suggest that at the Buenos Aires stream, the pollution probably comes from the sea towards the continent, whereas at the Quebra Pote, pollution is likely to originate from the continent and flow into the sea. We strongly encourage that thorough monitoring of mangrove forests is imperative for the survival and health of benthic communities