Ascorbic acid in the gonads of North Sea dab (Limanda limanda) during the reproductive cycle

Abstract

Total ascorbic acid was measured in the gonads of North Sea dab (Limanda limanda) throughout one reproductive cycle. In the ovaries, the concentration of ascorbate began to increase during the resting period in summer and reached maximum values of 400 μg .g fresh weight (fw)-1 at the onset of ovary maturation in fall. Concentrations declined rapidly towards the spawning period in spring and reached the lowest values of 80-100 μg .g fw-1. The maximum deposition of ascorbate in the ovaries amounted to 2.5 mg .organ-1 and occurred in late winter, corresponding to the beginning of the spawning period. In the testes, ascorbate concentrations were lower than in the ovaries, reaching a maximum of 170 μg .g fw-1 in early fall. The lowest values of 20-60 μg .g fw-1 appeared in winter and spring. In the testes the highest deposition of ascorbate amounted to 110 μg .organ-1 and appeared at the beginning of maturation. The sexual differences and seasonal variations are discussed in relation to the reproductive biology of dab.