POPULATION STRUCTURE OF UCA VOCATOR (HERBST, 1804) (DECAPODA, OCYPODIDAE) IN TWO MANGROVES FROM SÃO PAULO NORTHERN COAST, BRAZIL

COLPO KARINE; NEGREIROS-FRANSOZO MARIA LUCIA

Sao Pedro - SP - Brasil

Congreso; I Congresso Brasileiro sobre Crustáceos; 2000

Brachyurans of the genus Uca are very abundant in subtropical mangroves. The population structure of U. vocator from the mangroves of Indaia (23°24´ S and 45°03´ W) and Itapanhau (23°49´ S and 46°09´ W) rivers, SP, Brazil was investigated during one year. Crabs were sampled by two collectors during 30 minutes. For each specimen, the carapace width (CW) was measured and sex and ovigerous condition were recorded. A total of 1102 crabs from Indaia and 1032 from Itapanhau rivers were obtained. The number of males was significantly (p<0.05) greater than females for both sites (1 :0.61 and 1:0.79, respectively). Ovigerous females represented 2% of the sampled population from Indaia and 6.3% from Itapanhau. The crabs larger than the smallest ovigerous females were considered adult (10.9 mm, Indaia and 11.7 mm, Itapanhaú). The mean size for adults and young was statistically different between sites (p<0.05). The size frequency distribution was symmetric in Indaia, and asymmetric in Itapanhau, with constant recruitment during the study period. These features are typical of tropical and subtropical semiterrestrial brachyurans, suggesting a natural equilibrium of a population.