Abstract
Growth, metabolic rate, and energy reserves of Cherax quadricarinatus (von Martens, 1868) juveniles were evaluated in crayfish acclimated for 16 weeks to either 25ºC (temperature near optimum) or 20ºC (marginal for the species). Additionally, the modulating effect of ecdsyone on acclimation was studied. After 12 weeks of exposure, weight gain of both experimental groups acclimated to 25ºC (control: C25, and ecdysone treated: E25) was significantly higher than that of those groups acclimated to 20ºC (C20 and E20). A total compensation in metabolic rate was seen after acclimation from 25ºC to 20ºC; for both the control group and the group treated with ecdysone. A Q10value significantly higher was only observed in the group acclimated to 20ºC and treated with ecdysone. A reduction of glycogen reserves in both hepatopancreas and muscle, as well as a lower protein content in muscle, was seen in both groups acclimated to 20ºC. Correspondingly, glycemia was always higher in these groups. Increased lipid levels were seen in the hepatopancreas of animals acclimated to 20ºC, while a higher lipid level was also observed in muscle at 20ºC, but only in ecdysone-treated crayfish.
Highlights
The Q10 is the factor by which a reaction rate is increased by an increase of ambient temperature by 10°C reflecting the relationship of physiological processes such as metabolic rate, to acute temperature changes
This study was aimed to assess the effects of acclimation to a temperature lower than the optimum on: metabolic rate, the utilization of energy reserves, and growth rate of C. quadricarinatus juveniles
weight gain (WG) of the C25 group begins to be significantly (p
Summary
Most poikilotherms display compensatory mechanisms against temperature change; several species are even capable of full compensation and hold their metabolic rate at the same level they had at a higher temperature after an acclimation period to the new lower temperature (Hill et al, 2004). This process, known as metabolic compensation, allows poikilothermic species to minimize the effects of ambient temperatures on physiological processes and to maintain their level of activity at low temperatures (Lagerspetz, 2006). We hypothesized that juveniles acclimated to a sub-optimum temperature will be able to compensate their metabolic rate, being facilitated this process by ecdysone
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