| Bivalve mollusks of the continental shelf of Cabo Frio upwelling ecosystem were sampled monthly from February 1986 to February 1987 along a 30 to 60 m depth gradient. Mactra petiti Orbigny, 1846, and Tellina gibber Ihering, 1907 were constant species in 30 m; Nucula puelcha Orbigny, 1846, Adrana patagonica Orbigny, 1846, T. petitiana, T. gibber, and Corbula patagonica Orbigny, 1846 in 45 m; and N. puelcha, T. gibber, C. patagonica, and C. caribaea in 60 m. The number of rare species was similar along the depth gradient, ranging from six to ten species. The number of common species was higher in 60 m than in 30 m. Some species showed a continuous distribution but changed the frequency and abundance along the bathymetric gradient. The mean density was higher... |
