RESPONSES OF CHASMAGNATHUS-GRANULATA DANA (DECAPODA, GRAPSIDAE) TO SALT-MARSH ENVIRONMENTAL VARIATIONS

The relationship between annual abundance (individuals/m2) of the crab Chasmagnathus granulata Dana and selected environmental factors (temperature, salinity and dissolved oxygen) was investigated in a salt marsh in the Patos Lagoon estuary, southern Brazil. Sampling was performed on a monthly basis over 16 months. Highest abundances, which occurred during periods of moderate increasing temperature and salinity, may be explained by the species' reproductive and recruitment strategies. Burrows seem to attenuate temperature and salinity variations and the hypoxia to which crabs are constrained when burrowed is solved by metabolic depression. Although C. granulata is a good hyper-osmotic regulator, its resistance to low salinities is decreased when subjected to low temperatures, suggesting a temperature-salinity interaction.