Structure and dynamics of a shelf amphipod taxocoenosis in southeastern Brazil

The distributional patterns of amphipods were examined biannually (summer and winter) at 18 sites located between 10 and 120 m in depth over the continental shelf of São Paulo State in southeastern Brazil. Multivariate analysis showed that water masses and sea depth, primarily, and sediment texture, secondarily, are the factors structuring the amphipod assemblages. Ordination analysis disclosed three distinct assemblages: (1) a coastal assemblage influenced by the coastal water; (2) an inner shelf assemblage influenced by a mixed zone with coastal water and south Atlantic central water; (3) an outer shelf assemblage within the south Atlantic central water domain. Species diversity, which increased with depth, was related to environmental stability.