SPONGE DISTRIBUTION AT SERGIPE STATE, NORTHEAST BRAZIL

Sponges are among the most diverse and abundant components of benthic tropical communities. The aim of this study is to describe the spatial distribution of marine sponges at the continental shelf of Sergipe State, Northeast Brazil, to increase our understanding of the diversity and distribution of these marine taxa, since the sponge fauna of this region was poorly-known. The collection occurred during the years of 2001 and 2003 by trawling. Samples were taken along six horizontal transects at 10, 20 and 30 m isobaths. In each of the 18 collection sites, we calculated Shannon’s species diversity (H’), Pielou’s evenness (J) and the wet weight (W) of each species. Sponges occurred only in half of the collection sites. Of the 39 species found, 10 were new to science, three of which are still being described. The total Shannon’s diversity and Pielou’s evenness in all collection sites pooled together were H’=1.22 and J=0.77. The total sponge wet weight was about 11.03 kg. The species more abundant were Hyattella cavernosa and Ircinia strobilina (W=1.63 Kg and W=1.59 Kg, respectively), which together with Aiolochroia crassa , Aplysina sp. and Cinachyrella kuekenthali , were the species more widely distributed in the coast. The sponges in sites with gravel substrate were more diverse and abundant (H’=0.87 ± SD=0.22; J=0.75 ± SD=0.07; W=10.58 Kg), followed by sites with sandy substrate (H’=0.13 ± SD=0.15; J=0.31 ± SD=0.43; W=0.37 Kg) and sites with muddy substrate (H’=0.04 ± SD=0.1; J=0.15 ± SD=0.34; W=0.07 Kg). The ANOVA performed show significant differences in diversity and abundance between sites of three types of substrate (F=23.65 and p<0.01 for abundance; F=47.96 and p<0.01 for diversity). Besides, cluster analysis using Jaccard’s coefficient on qualitative (presence/absence) data grouped the sites of similar substrate. The sponge community of Sergipe State has intermediate richness and low diversity when compared with others areas in Brazil. This fact could be explained by the predominance of sand and muddy substrates at continental shelf of Sergipe State. Further studies will be made to establish which variables better explain the distribution of sponges in this region.