Effect of ecdysone on thermal acclimation of Cherax quadricarinatus juveniles

CHAULET, A.; PRYMACZOK, N.C.; RODRÍGUEZ, E.M.

Kuopio

Congreso; 17 th Symposium of the International Association of Astacology; 2008

International Association of Astacology

Juveniles of Cherax quadricarinatus with a body weight (BW) of 1.00 ± 0.03 g (N=48) were randomly assigned to four experimental groups (N=12/group). Two groups were fed on fish commercial food (Tetra Diskus ®) and acclimated to either 22 or 27 ºC (groups T22 and T27 respectively), while the other two were fed on the same diet added with ecdsyone at 10-10 mol/g BW and also acclimated to either 22 or 27 ºC (groups E22 and E27 respectively). Each juvenile was placed in a glass recipient having 800 mL of dechlorinated freshwater, with a refuge and continuous aeration. Photoperiod was held at 14:10 (L:D). All animals were daily fed at a 3 % of their biomass throughout the experiment. Water from all recipients was renewed twice a week. After five months, the oxygen consumption (metabolic rate, MR) of each juvenile was acutely measured in a closed chamber by means of a digital oxymeter, at both 22 and 27 ºC. Mean MR of T22 group was lower than that of T27 group at both temperatures, indicating that no metabolic compensation seems to have occurred in normal conditions On the contrary, mean MR of E22 group was always higher than the corresponding to E27 group, suggesting that a certain metabolic compensation has been mediated by the ecdysone added to food. Since 22 ºC is far from being the optimal temperature for growing and survival of C. quadricarinatus juveniles, the possible compensatory effect of ecdysone is discussed  as a potential tool for aquaculture.