Environmental factors modulating the abundance and distribution of Callinectes danae (Decapoda: Portunidae) from two areas of the southeastern coast of Brazil

Abstract

The distribution and abundance of marine organisms are directly or indirectly a function of biotic and abiotic features such as sediment and water properties. In this study we analyzed the spatial and temporal distribution of Callinectes danae in two distinct littoral areas of the northern coast of the State of São Paulo, Brazil and associated them with local geomorphologic features and environmental factors. We collected specimens on a monthly basis, from July 2001 to June 2003, using a fishing boat equipped with double-rig net, in two locations: Ubatuba (UBA) and Caraguatatuba (CAR). Collecting was carried out in seven transects with different depths, which were further subdivided into two regions: bay region (5, 10, 15 and 20 m deep); and inner shelf region (25, 30 and 35 m deep). Samples from different periods and transects differed significantly in abundance. A positive correlation was found between the abundance of C. danae and the following parameters: temperature at the bottom, organic matter content and Phi (grain diameter). By contrast, a negative correlation was established between specimen abundance and salinity at the bottom. The total abundance was highest in 5 m deep transects in both regions. Summer was the season when individuals were least abundant in both areas. We concluded that the spatial and temporal distribution of C. danae are determined by a set of environmental factors and not just by one single factor.