Influence of depth on bryozoan richness and distribution from the continental shelf of the northern coast of Bahia State, north-eastern Brazil

Abstract

Biological and abiotic processes infl uence ecosystem structure and species distribution. For bryozoan assemblages, depth, substratum and habitat structure are among the main factors infl uencing their distribution. Ecological studies on bryozoan fauna from Brazil are scarce and factors affecting the distribution and/or diversity of this common group are obscure. Here we attempted to verify the infl uence of bathymetry on bryozoan richness on the north shore of Bahia State, northeastern Brazil. We identifi ed 57 bryozoan taxa, comprising 35 families and 50 genera, all belonging to the Cheilostomata. Retevirgula multipunctata Winston, Vieira & Woollacott, 2014 and Tetraplaria dichotoma (Osburn, 1914) and the genus Aimulosia Jullien, 1888 were recorded for the fi rst time from Bahia State. Species growing as encrusting sheets were dominant at all depths. There was a signifi cant difference in richness among samples at different depths, with highest values of richness at 40 meters (Kruskal-Wallis Test). Analysis of similarities revealed a signifi cant difference among the bryozoan assemblages, mainly when comparing assemblages from 10 and 20 meters with deeper ones. Also, shallower assemblages composition varied much than assemblages from 30 and 40 meters. Since depth is a proxy for several environmental parameters, further studies are needed to identify other factors infl uencing bryozoan distribution.

Morphotectonic and morphostructural investigation in northwestern Minas Gerais State, Brazil: a lineament mapping assessment

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