The diversity and richness patterns of bivalve molluscs were studied on the continental shelf of Ubatuba (23º38'S, 45º14'W and 23º25'S, 44º51'W) between 15-120 metres depth. The samples were taken with a rectangular dredge and a beam trawl. The results showed higher values of richness, diversity and evenness for inner shelf (from coast to nearly 50 m depth) and greater values of abundance for outer shelf (from 50 to around 120 m depth). This pattern might be due to the higher instability of the inner shelf, which is influenced by the seasonal intrusion of the South Atlantic Central Water (SACW) and the occurrence of cold fronts. Sanders' rarefation curves, distribution and abundance curves and DIMO model were used and the results compared. The Qinghong's model proved to be a good tool for summarizes the results of diversity in a such plural account.
Biodiversity; community structure; macrobenthos; spatial distribution; soft-bottom
