Estudo da relação entre a cobertura do mangal e a distribuição do caranguejo do gênero Uca no estuário dos Bons Sinais, província da Zambézia

Abstract

The violin crab of genus Uca (Leach, 1814) is characterized the high level of sexual dimorphism and globally distributed in tropical and subtropical countries in Asia, Africa, America and Oceania. Currently, 97 species are described for genus Uca and several aspects such as ecology and species physiology have been described. The present study focused on the mangrove species composition and density of Uca crab in two areas of Bons Sinais Estuary, one with higher mangrove coverage and other with low coverage. Sampling was carried out during August-November 2017 for both mangrove and Uca populations. The data showed that mangrove density was higher at Ilha do Chuabo Dembe with 1800 tree/hectare and low at Inhangome with 988 trees/hectare; the same pattern was followed by Uca spp with high density at Ilha do Chuabo Dembe of 33.92 ind/m2 while at Inhangome the density found was 21/08 ind/m2. Statistical analysis showed that both sampling areas had a moderate and negative correlation between mangrove density and Uca crab density, which means that high density of mangrove results in low density of Uca crab. The intricacies of Uca distribution are related to the feeding behaviour of the species, as the higher density areas are generally at low tide watermark where Uca feed during low tide and build the holes for court and residence and middle and high tide zones. Other factors, such as sediment composition should be taken into attention to study the ecology of Uca spp.