Effect of temperature on the egg and yolk-sac larval development of common pandora, Pagellus erythrinus

Temperature is one of the most critical environmental factors for fish ontogeny, affecting the developmental rate, survival and phenotypic plasticity in both a species- and stage-specific way. In the present paper we studied the egg and yolk-sac larval development of Pagellus erythrinus under different water temperature conditions, 15 degreesC, 18 degreesC and 21 degreesC for the egg stage and 16 degreesC, 18 degreesC and 21 degreesC for the yolk-sac larval stage. The temperature-independent thermal sum of development was estimated as 555.6 degree-hours above the threshold temperature ( the temperature below which development is arrested), i.e. 7 degreesC for the egg and 12.1 degreesC for the yolk-sac larval stage. Higher hatching and survival rates occurred at 18 - 21 degreesC. At the end of the yolk-sac larval stage, body morphometry differed significantly ( p< 0.05) between the temperatures tested. The growth rate of the total length increased as temperature rose from 16 degrees C to 18 degrees C, while in the range of 18 - 21 degrees C it stabilized and was independent of water temperature. The estimated Gompertz growth curve for the yolk-sac larvae of P. erythrinus was TL = 3.035 center dot e (-0.505 center dot e -0.041 center dot t) (r(2)= 0.992) for the 16 degrees C, TL = 2.926 center dot e (- 0.509 center dot e - 0.106 center dot t) (r(2)= 0.991) for the 18 degrees C and TL = 2.801 center dot e (-0.482 center dot e - 0.104 center dot t) ( r(2)= 0.981) for the 21 degrees C treatment. The efficiency of vitelline utilization during the yolk-sac larval stage was higher at 18 degrees C.