Estrutura populacional e distribuição espaço-temporal dos Portunídeos (Crustacea: Decapoda) da Baía de Sepetiba, RJ

Abstract

The portunids more abundant in Sepetiba Bay are Callinectes ornatus, Callinectes danae and Achelous spinimanus. This work aimed to study the population structure and spatial-temporal distribution of these three species in Sepetiba Bay, RJ. Samples were collected monthly between September 2011 and August 2012 in three areas of Sepetiba Bay in relation to salinity gradient: internal, intermediary and external. Was captured a total of 4,116 specimens of which 2546 were C. ornatus, 1244 C. danae and 326 A. spinimanus. The sex ratio differed from 1:1 among adults of the three species, with a predominance of females in C. danae. Comparing the two congeneric species, among demographic groups, there was a significant difference only between the proportions of ovigerous females. In C. ornatus, ovigerous females have been infrequent, however in C. danae was representative throughout the entire study period. The carapace width of males of the three species was greater than that of females. It was not possible to an indication of an seasonal pattern of distribution during the study period, possibly due to the occurrence of atypical fluctuations of abiotic factors. However it was observed a certain pattern of temporal variation in species abundance and their demographics. The correlations with abiotic factors were positive for salinity in ovigerous females of Callinectes danae and positive pluviosity for both sexes of Callinectes ornatus. The spatial distribution also varied depending on the species and size of the carapace. Callinectes ornatus has presented distribution of adult individuals in the external area and juveniles in the intermediary. The juveniles and adult males of Callinectes danae were more abundant in the internal area. The adult individuals of Achelous spinimanus were more abundant in the intermediate area.