Benthic biodiversity along the central coast in the Brazilian EEZ (OBIS South America, BRAZIL) (OBIS South America, BRAZIL)
The main objectives of the REVIZEE Program were the species inventory and the evaluation of the sustainable yield of living resources from the Brazilian Exclusive Economic Zone. In this context, the benthos has an important role, since it is one of the main components of marine food webs, being food to many pelagic and demersal fishing resources or as a living resource itself. This work presents a characterization of the phyto- and zoobenthos from the continental shelf and slope of the central Brazilian coast, between Salvador, in Bahia (13°00’S- 38°31’W) to São Tomé Cape, in Rio de Janeiro State (22°12’S - 41°15 W). Samples were taken in 222 stations, during 4 oceanographic cruises (1996-2002). Sampling was made basically using rectangular dredges, Van Veen grab and a box-corer. The region presents a rich benthic fauna and flora, especially at areas such as Abrolhos reefs, Vitória-Trindade and Almirante Salda nha seamounts and near Salvador (BA) and São Tomé Cape (RJ). Macroalgae occurred mainly at continental shelf and upper slope, with green algae as the most rich and abundant group, despite the biomass contribution of brown algae in some places. Thirty-one macrobenthic groups were found, with one third occurring in more than 70% of stations. Most organisms belong to epifauna (animals living on the substrate), in part due to the kind of equipment used (basically dredges) and also to the main bottom type found in the region (mainly biogenic substrata, with algae nodules and calcareous sediment). This substrate favours the presence of epifauna, composed mainly by sessile animals such as sponges and corals, the most abundant organisms in terms of biomass (ca. 85%). Infauna (animals that live buried in the sediment) was represented by various taxa of polychaets, sipuculans, echinoderms, small crustaceans and mollusks, the two latter being numerically dominant. The macrofauna composition and abundance were r elated to botto m characteristics and local depth, with organisms being dominant in shallow waters (up to 100m depth) with biogenic substrate such as red algae nodules. Environmental heterogeneity given by differences in shelf and slope substrata, the presence of a biogenic bottom, estuaries, coral reefs, seamounts and canyons provides a great variety of microhabitats and it seems to be responsible for high benthic diversity found. Despite the lack of a precise evaluation of the economic potential of benthic living resources, the REVIZEE program provided an excellent species inventory, identifying species with economic value, new species occurrences to Brazilian coast and new species to Science, specially from the outer shelf and continental slope.
Apr 3, 2007
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