Effects of parathion on ions and water balance in the estuarine crab Chasmagnathus granulata (Decapoda, Grapsidae).

MONSERRAT, J.M.; RODRÍGUEZ, E.M.; ANSALDO, M.

NAUPLIUS

Sociedade Brasileira de Carcinología

Año: 1994 vol. 2 p. 87 - 97

0104-6497

The effect of the organophospate insecticide parathion on ionic concentratios and water content of the estuarine crab Chasmagnathus grnulata was studied under different experimental  conditions. No effects on hemolymph K+ and Na+ concentrations were noted in any case, indicating no apparent effects of parathion on ionic regulation processes. In the first experikent, involving a pre-exposure to parathion and 12 ppt salinity, followed by a final exposure to clean water at different salinities (4, 12 or 36 ppt), both a higher branchial and body water content were detected at all salinities. These results could be related to the releasing of osmotically active organic metabolites in blood as response to parathion pre-exposure. In the second experiment, crabs were acclimated for 32 days to different pathion-free salinities (7.5, 15 or 30 ppt), and exposed for a subsequent period of 10 days to parathion at the same salininities. In this case, by the third day of final exposure an increase in body water content was also noted, but the effect of parathion was salinity dependent, indicating a possible damage caused by the insecticide to adaptative osmoregulatory mechanisms that crabs may have developed during the previous acclimation  period. This effect was compensated by the tenth day of exposure to parathion.