Distribuição das espécies de chaetognatha na plataforma continental de Sergipe e Alagoas

Abstract

The present study investigated the Chaetognatha species distribution in the continental shelf off Sergipe and Alagoas States and its relation to the abiotic variables. Samples were collected at eighteen stations along six transects, perpendicular to the coast line in December (2001 and 2002) and June (2002 and 2003), corresponding to the dry and rainy seasons, respectively. Oblique hauls were done with plankton net, mesh size 200 μm. Temperature, salinity, pH, dissolved oxygen and nutrients were measured in three levels of the water column. Subsamples were taken using a Stempel pippette. Correlations analysis between Chaetognatha distribution and environmental parameters were studied using canonical correspondence analysis. Sagitta tenuis and S. enflata were the most adundant species, following by S. hispida, Sagitta spp., Krohnitta pacifica, Pterosagitta draco and S. bipunctata. Density values ranged between 9 ind.m-3, in December 2002, and 4,473 ind.m-3 in June 2002, when Sagitta tenuis and S. enflata were more abundant. Density average values decreased from stations located at 10 meters to that located at 30 meters depth. Temperature, phosphate, salinity and water transparence were correlated (p<0,05) to the Chaetognatha species distribution.