Relações entre distribuição e abundância de larvas de Trichoptera (Insecta), em córregos de cerrado no entorno do Parque Estadual da Serra de Caldas (Caldas Novas, estado de Goiás)

Abstract

Abundance-occupancy relationships of Trichoptera larvae, estimated in two seasons, were compared to evaluate the following hypothesis: hydrologic instability during the rain season is the main mechanism which reduces the magnitude of these relationships in streams located in the Cerrado region, Centre-West of Brazil. The larvae density was determined from 18 sampling stations in a region surrounding the Parque Estadual da Serra de Caldas, Caldas Novas, Estado de Goiás, by Surber sampler. The distribution of each taxon was given by the number of occurrences in the region. During the dry season (July), a significant correlation between abundance-occupancy was detected (r =0.606; n = 20; P < 0.005). On the other hand, such relationships were not significant during rainy periods. These results support the hypothesis that, during the periods of hydrological stability, abundance and distribution patterns of Trichoptera were controlled by the interaction of organisms tolerance and environment gradients. Besides, the relative importance of stochastic and deterministic, acting on benthonic insects may be temporally dependent.