The effect of water temperature on the number of moults and growth of juvenile signal crayfish Pacifastacus leniusculus Dana
2009
Kozak, P.,Jihoceska Univ., Vodnany (Czech Republic). Vyzkumny Ustav Rybarsky a Hydrobiologicky | Buric, M.,Jihoceska Univ., Vodnany (Czech Republic). Vyzkumny Ustav Rybarsky a Hydrobiologicky | Kanta, J.,Jihoceska Univ., Vodnany (Czech Republic). Vyzkumny Ustav Rybarsky a Hydrobiologicky | Kouba, A.,Jihoceska Univ., Vodnany (Czech Republic). Vyzkumny Ustav Rybarsky a Hydrobiologicky | Hamr, P.,Upper Canada Coll., Ontario (Canada). Science Dept. | Policar, T.,Jihoceska Univ., Vodnany (Czech Republic). Vyzkumny Ustav Rybarsky a Hydrobiologicky
The growth rate, frequency of moulting, and intermoult intervals of juvenile Pacifastacus leniusculus were studied under experimental conditions over a period of 3 months. Juveniles were reared individually in small boxes at two different temperatures: 14.31+/-0.64 deg C (cold water, C) and 20.54+/-0.69 deg C (warm water, W). Although the average weight and length of consecutive stages were similar at both temperatures, juveniles in W attained more moults. Within the age group juveniles achieved a higher length and weight in W than in C. Three month-old animals reached 147 mg and 18.5 mm in C at the 6th stage of development, and 259 mg and 22.2 mm in W at the 8th stage. Specific growth rate (SGR) decreased (5.6 and 10.4 for C and W in the first stage, respectively) and reached final values of 1.4 and 1.5 after 3 months of growth. SGR was significantly higher in W and showed negative correlations with the number of days after hatching and number of moults. Duration of intermoult periods was significantly influenced by water temperature, with five moults attained in C compared with seven in W. All intermoult periods were significantly longer in C than in W. The average percent weight and length increments decreased with increasing number of moults, length, weight and number of days after hatching. Increments were higher in W than in C. However, the final values were similar at both temperatures (about 36% and 11% for weight and length, respectively). Although the temperature influenced growth due to the number of moults, the duration of individual intermoult periods did not affect the weight and length of juveniles in particular stages.
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