Estudo de alguns aspectos eco- etológicos do caranguejo dotilla fenestrata na praia do bairro Triunfo, Maputo

Abstract

The species Dotifla fenestrata was studied at Triunfo beach, Maputo, in March, April, June and July 1994. The study aimed at aspects related to distribution, density, biomass and also the population size structure and some aspects of the behavior of this species. The samples were taken along two level transects, the first located near the maximum tidal line and the second near the minimum tidal line. Sampling was done during low tide. It was verified for both transects that: This species occurs throughout the entire sampling period, and the mean density was 448/m2 and 289/m2 respectively for the first and second transects. Biomass seems to vary with density. According to Morisita's index, the pattern of distribution of individuals in the two transects is gregarious. Males, females and juveniles occur throughout the entire sampling period and at all levels, inferior, medium and superior. Adults (male and female) make up 52% ​​of individuals in transect 1; while in transect 2 they correspond to 70%. There is a dominance of males throughout most of the sampling period. There is a strong correlation between the size (width of the carapace) of individuals and their weight (g). There are ovated females on all sampling days In relation to behavioral aspects, it was found that: There are differences in the speed of emergence of crabs in tides of different amplitude. There seems to be no preference in the direction of food movement. (TRADUÇÃO NOSSA)