Distribuição espacial e temporal de espécies de Bledius (Coleoptera, Staphylinidae) em praias arenosas no sul do Brasil

Abstract

Staphylinidae beetles are common in coastal areas fooded by tides, such as sandy beaches, mangroves, salt marshes, estuaries. The aim of this work was to investigate the spatial distribution and temporal variation in abundance throughout the year of the species sampled along two sandy beaches (Assenodi and Cem) in Pontal do Paraná, Brazil. Weekly samples with a 15 cm diameter PVC corer (0.017 m²) buried 5 cm in sediment depth were done from January to December 2012. Assenodi beach showed sediments with high humidity values at supralittoral and backshore. In this beach, Bledius bonariensis was the dominant species, and together with B. fernandezi occurred in the upper beach portion during the whole year. Cem beach showed sediment with high humidity values only at midlittoral and related to the rise and fall of the tide. Here, B. hermani was the dominant species, with B. bonariensis occurring sporadically in some autumn and winter months and related to an increase in precipitation. B. hermani presented a great variation in abundances, with highest values associated with high summer temperatures. Bledius species showed a clear spatial separation related to different environmental requirements that enable their co-occurrence within the same beach, due to environmental variations during the year.