In the present study, Siberian sturgeon (Acipenser baerii) larvae were subjected to 16°C, 19°C and 22°C from hatching until the yolk-sac was completely absorbed. Sampling was performed at hatching, schooling and complete yolk-sac absorption stage. Larval development length, survival rate, somatic growth, whole body cortisol and IGF-1 expression were assessed at the same developmental stage for each temperature, in order to evaluate the impact of temperature during the endogenous feeding phase in this species.. Larvae subjected to 22°C showed a faster absorption of the yolk-sac than larvae subjected to 19°C or larvae subjected to 16°C. There were no significant differences across temperatures regarding overall survival rate Larval weight significantly increased from one stage of development to the other. Until the schooling stage, there were no differences concerning larval weight but, at the yolk- sac full absorption stage, larvae reared at 16°C weighed significantly more than those reared at 19°C (P <.0.05). Whole body cortisol significantly increased from schooling to the yolk-sac absorption stage. At schooling, larvae reared at 16°C showed a lower level of cortisol than those reared at 19°C or 22°C (P < 0.05). Also at the end of the trial larvae reared at 16°C presented lower cortisol levels than those reared at 19°C or 22°C, but these differences were highly significant (P < 0.01). IGF-1 immunopositivity was particularly evident at 16°C than at 19°C or 22°C both in schooling and in the yolk-sac absorption stage. These results suggest that larvae in this stage of development are sensitive to temperature regimes and that cooler temperatures could be more suitable for larval development. It appears, indeed, that lower temperatures in this phase of development of Siberian sturgeon larvae may have a positive effect on growth and that higher temperatures may lead to a stress response.
Environmental temperature variation on reared Acipenser baerii yolk-sac larvae: effect on cortisol and IGF-1 skeletal muscle fibres.
Bertotto D.;Radaelli G.;
2017
Abstract
In the present study, Siberian sturgeon (Acipenser baerii) larvae were subjected to 16°C, 19°C and 22°C from hatching until the yolk-sac was completely absorbed. Sampling was performed at hatching, schooling and complete yolk-sac absorption stage. Larval development length, survival rate, somatic growth, whole body cortisol and IGF-1 expression were assessed at the same developmental stage for each temperature, in order to evaluate the impact of temperature during the endogenous feeding phase in this species.. Larvae subjected to 22°C showed a faster absorption of the yolk-sac than larvae subjected to 19°C or larvae subjected to 16°C. There were no significant differences across temperatures regarding overall survival rate Larval weight significantly increased from one stage of development to the other. Until the schooling stage, there were no differences concerning larval weight but, at the yolk- sac full absorption stage, larvae reared at 16°C weighed significantly more than those reared at 19°C (P <.0.05). Whole body cortisol significantly increased from schooling to the yolk-sac absorption stage. At schooling, larvae reared at 16°C showed a lower level of cortisol than those reared at 19°C or 22°C (P < 0.05). Also at the end of the trial larvae reared at 16°C presented lower cortisol levels than those reared at 19°C or 22°C, but these differences were highly significant (P < 0.01). IGF-1 immunopositivity was particularly evident at 16°C than at 19°C or 22°C both in schooling and in the yolk-sac absorption stage. These results suggest that larvae in this stage of development are sensitive to temperature regimes and that cooler temperatures could be more suitable for larval development. It appears, indeed, that lower temperatures in this phase of development of Siberian sturgeon larvae may have a positive effect on growth and that higher temperatures may lead to a stress response.Pubblicazioni consigliate
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