Population Biology of the Crab Goniopsis Cruentata: Variation in Body Size, Sexual Maturity, and Population Density

We studied two key traits in the life of organisms, body size and sexual maturity, and a population attribute, density, of the crabGoniopsis cruentata. Also, we evaluated the role of environmental factors on population density. We caught crabs in two mangrove sites that are under different influence of tidal fluctuation, and obtained pH and salinity of mangrove soil from each site as well as rainfall data for the period of study. Both body size and sexual maturity differed between sites, in which individuals from the small-bodied population matured at smaller sizes than their counterparts from the large-bodied population, which matured at larger sizes. In addition, density of the small-bodied population was lower than that of the large-bodied one. We did not detect any influence of the environmental factors on population density. Our finding indicate that key life history traits and population characteristics can vary on a very small spatial scale which may help to further elucidate the biology of natural populations.