Dinâmica espaço-temporal da macrofauna bentônica em duas praias arenosas da ecorregião marinha leste do Brasil
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Data
2015-06-16
Autores
Coutinho, Mariane Silva
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Universidade Federal do Espírito Santo
Resumo
Sandy beaches are dynamic environmentalunder strong interaction among sand grain size, waves energy and tidal variation. This type of beach hasa great economic and ecologic importance because they dominate the most coastal areas. Associated with beaches sediments, benthic invertebrates assemblages are closely related to hydrodynamic, chemistry and biological forces of these ecosystems, resulting in spatialand temporal distribution patches. These heterogeneity assemblagesoccurin local, regional and also latitudinal spatial scales, exhibit biogeographic patterns well know in benthic abundance, biomass and species richness.Numerous efforts in description of benthic macrofauna spatial-temporal variation on sandy beaches were realized in Brazil, mostly concentrated in Southeastern Marine Ecoregion between Rio de Janeiro, São Paula and Paraná States.This study search understand spatial and temporalscales of variability in benthic macrofauna (i.e.>500µm) through a hierarchical sampling oftwo sandy beaches within Eastern Marine Ecoregion of Brazil in two different times (the winter of 2011 and the summer of 2012). By sampling on beaches with similar morphodynamic, we tested the hypothesisthat spatial variation (i.e., meters to hundreds meters scales) in benthic assemblages structure will be more significant and directly related to abiotic variables compared to seasonal fluctuations of temperature, productivity (measure by availabilityorganic sediment) and morphodynamic beach. As expected, the beaches showed small spatial and temporal differences in abiotic and morphodynamic, but some differences in faunal composition were evident. Hierarchical sampling showeddifferencesin faunal composition and density in local spatial scales (meters to hundreds meters) and temporal scales (winter and summer). The macrofauna abundance and composition respondeddirectly to the contentof organic matter and sand grain size. The beaches of Eastern Marine Ecoregion had some particularpatterns compared to other beacheson Brazilian coast, as the presence of Nemertea and Oligochaeta betweenmacrofauna. In general, we confirm the hypothesisthat spatial variability of macrofauna assemblages of these beaches is greaterthansmall spatial scales duechanges sedimentary parameters