Spatial Distribution of Uca sindensis (Crustacea, Ocypodidae) along the coast of Pakistan

Spatial distribution of Uca sindensis was studied along the coast of Pakistan. The density, size distribution, population structure, sex ratio and handedness were investigated. U. sindensis crabs were collected through quadrate (0.5 m2 quadrates were placed during low tide periods) and transect (low tide mark to high tide mark) method from nine different sites along the coast. Results indicated that the substratum properties (organic content, size,and heterogeneity) were of primarily importance for the distribution of U. sindensis. The spatial variation was observed in the density distribution and was ranged from 4 to 48 m-2. The overall sex ratio was differed significantly from the expected 1:1 (χ2 =22.4; P = 0.004). The sizes of the male and female crabs were significantly different at all studied sites. The carapace (CW) of males ranged from 8.3 to 17.3 mm and of females from 6.2 to 14.4 mm indicating sexual dimorphism. The occurrence of dextral and sinistral males was overall in the 1:1 ratio.