Polychaete associations in a subtropical environment (Sao Sebastiao Channel, Brazil): A structural analysis

Analysis of polychaetes from 60 quantitative soft bottom samples (November 1993 - August 1994) from the Sao Sebastiao Channel at 10 to 45 m yielded 126 species from a total of 12,003 individuals. The distribution of both the bottom sediment type and species was patchy. Abundance data were analysed with multivariate techniques and revealed a strong correlation between species and sediment variables. Polychaetes were more diverse, abundant and richer in species number in those sites with higher sandy fractions. On the other hand, sites where silt, clay and organic carbon predominated showed a poor annelid fauna. Here, pollution by the sewage discharge of a submarine pipe, the oil terminal activities and the clandestine oil tank washing have an important impact on the bottom fauna. Only little temporal variation in the composition of the polychaete associations was found during the study period.