Diversity of Bivalve Mollusks Associated with Macroalgae on the Continental Shelf in the States of Alagoas Sergipe and Bahia Northeastern Brazil

摘要

The phytal environment is a complex system that involves the association between marineorganisms and macroalgae. In this paper, we investigate the diversity of bivalvesassociated with macroalgae on the continental shelf between the states of Alagoas andBahia, including Sergipe, in northeastern Brazil. Macroalgae and associated fauna werecollected during two sampling campaigns under the MARSEAL project (February and July 2011[dry and rainy seasons, respectively]), covering 24 stations and three isobaths (10, 25and 50 m). The following ecological descriptors were calculated: abundance (N), richness(S), diversity (H') and evenness (J). A total of 1384 individuals from 20 families, 28genera and 44 species were obtained. Arcidae was the most abundant group, followed by thefamilies Pteriidae and Mytilidae. The most abundant species were Arcazebra, Anadara sp. 1 and Pinctada imbricata,representing 71% of the total abundance. The families Arcidae, Corbulidae and Mytilidaewere considered constant, as they occurred in more than 50% of the samples. A higherabundance was recorded during the rainy season. No seasonal differences were foundregarding S, H' or J. Richness increased with increasing depth, whereas the other indices(N, H' and J) were not influenced by bathymetry. This reveals that the 50 m isobath has agreater support capacity and houses richer, more diverse fauna. Bivalve richness andcomposition data from this study expand the information on mollusk biodiversity associatedwith the phytal environment on the continental shelf off northeastern Brazil.