Estudo da distribuição, abundância, e aspectos reprodutivos da scylla serrata no saco da Ilha da Inhaca

Abstract

The study on the distribution, abundance, and reproductive aspects of the crab scylla serrata (Forskal) was carried out from January to February on Inhaca Island. The biomass, density, population structure and reproductive aspects (frequency of ovated females), maturation of males and females were investigated in different habitats that make up the intertidal zone of the Inhaca bag. The aim of the work was to study the variation of the above mentioned parameters as a function of habitat, tides and moon cycles. The samplings were carried out in two zones: -Forest zone consisting of three habitats according to the specified predominant mangrove composition (Rhyzophora mucronata, Avicennia marina and Rhyzophora mucronata +Ceriops tagal). -Exposed area, so called due to the absence of vegetation cover, in this area cages were used to capture crabs, while in the first area the captures were carried out using the hoe method. The average biomass and population structure showed variations along the habitats, as well as in relation to the tides, although there are no variations in the different phases of the moon. Density and reproductive aspects did not show a significant evolution in general in relation to the moon phases, but showed a great variation in the analyzed habitats. The females and males studied were made up of juveniles and sub-adults, and the occurrence of adult individuals was not reported. The ratio of males to females was 2:1 in all habitats analyzed except the mud habitat where the ratio was 1:1. The studied crabs were mostly in the inter molting stage. Despite the smaller number of samples, it is clear that sexual maturity in both sexes is reached with a carapace width greater than 90 mm, regardless of the analyzed zone, however it appears that different population categories explore the intertidal zone at different levels .