Adaptive Osmotic Responses of Macrobrachium Acanthurus (Wiegmann) and Macrobrachium Carcinus (Linnaeus) (Decapoda, Palaemonidae) From the Southern Gulf of Mexico
The osmotic response of adult prawns, Macrobrachium acanthurus and Macrobrachium carcinus from the coast of the southern Gulf of Mexico was studied in an adaptive sense. Four experimental treatments were employed to test the effects of gradual and abrupt changes in salinity. M. acanthurus is a hyperosmotic regulator in salinities between 0 and 20 psu, reaching its isosmotic point at 632 mOsm kg-1. Beyond this point, the species is hyposmotic. M. carcinus is a hyperosmotic regulator in salinities from 0 to 15 psu, with an isosmotic point at 490 mOsm kg -1 and showing a tendency to hypoconforming in high salinities. The maximum salinities tolerated were 25 psu for M. acanthurus and 30 psu for M. carcinus.