Physiological responses of the freshwater crayfish, Cherax quadricarinatus, to different experimental salinities

PRYMACZOK, N.; MEDESANI, D.A.; RODRÍGUEZ, E.M.

Buenos Aires

Congreso; XXII Congreso Latinoamericano y 1ro Ibero-Americano de Ciencias Fisiológicas; 2006

Sociedad Argentina de Fisiología

Adult male crayfish Cherax quadricarinatus were exposed to the salinities of  0 (control), 7.5, 15, 25 and 35 gL-1 for 3 weeks. Survival, oxygen consumption rate, hemolymphatic levels of glucose, lactate, sodium, potassium and free amino acids (FAA), as well as FAA concentration in muscle, were determined. Survival was significantly reduced (p<0.05) only at the highest salinity assayed, but both locomotion and feeding were reduced at the two highest concentrations. Although no significant differences (p>0.05) were detected in the oxygen consumption rate, a noticeable drop of this variable was noted at 35 gL-1, while in hemolymph both a significant (p<0.05) increase of glucose and decrease of lactate were observed at that salinity. These results are suggesting that a metabolic depression could have taken place at the highest salinity, probably involved in the exhaustion phase of the stress syndrome. Concerning ions, both hemolymphatic sodium and potassium increased with salinity, but just at 25 and 35 gL-1 a clear overpassing of ionoregulatory mechanisms was observed. No significant (p>0.05) change was seen in hemolymphatic FAA as salinity increased, but FAA content in muscle showed an increase parallel to that of hemolymphatic sodium, in accordance with their expected function in the isosmotic regulation of muscular cells.