Effect of incubation temperature on eggs and larvae of lumpsucker (Cyclopterus lumpus L.)

Abstract

In this study the aim was to investigate how incubation temperature effected lumpsucker eggs and larvae; by comparing early cell symmetry, egg/embryo development, mortality, hatching success and early larvae size weight and histomorphology. Two batches of eggs were incubated at 3 temperature regimes; 1- Ambient seawater 4-6°C (cold), 2-Ambient seawater for 10 days then gradually increased to 10°C (gradient), 3- constant 10°C seawater (warm). Early cell symmetry, development and hatching time was similar with regard to day degrees between all temperature groups, although faster (in days) with warmer temperature. The eggs incubated in cold water had the highest egg mortality and lowest hatching success. The warm group had lowest egg mortality while the gradient group had highest hatching success. The gradient group also had the most synchronized hatching; most of the eggs hatched during the first day. The warm and cold group both had a hatching peak 3 days post first hatching. The larvae mortality was highest in the warm group and lowest in the gradient group. The cold group had the longest, heaviest and thickest larvae followed by the gradient and warm group respectively. Newly hatched larvae from the warm group had most body deformities. Larvae from all groups kept fed at 10°C for two weeks showed a difference in body size; larvae from the cold regime being largest. No difference between groups were found in mortality or body deformeties. Studies of organ and tissue histomorphology of hatched and two week old larvae did not reveal differences between the temperature groups. This study demonstrated that incubation temperature will effect: mortality, hatching success and early larvae conditions of lumpsucker. A gradual rise in incubation temperature at an early embryo stage seemed to be most beneficial