Morphological, biochemical and histological analysis of mud crab ovary and hepatopancreas at different stages of development

This study describes the fatty acids, total carotenoids, and cell diameter characteristics of the female ovary and hepatopancreas of the mud crab, Scylla olivacea, with comparisons at different ovarian maturation stages. Seventy-one S. olivacea individuals at all stages of ovarian maturation were sampled from the Setiu wetlands, Terengganu, Malaysia. The ovary and hepatopancreas of each crab were used for morphological studies, histological and biochemical analyses (fatty acid composition and total carotenoids). Morphological observations indicated there was an increase in ovarian gonado-somatic index (GSI), with color changes from translucent to dark red; however, a relatively consistent hepato-somatic index (HSI) in the hepatopancreas, with the color ranging from yellow to yellowish-brown. Histological analysis indicated that oocyte diameter was positively correlated with GSI. Hepatopancreatic tubules had a relatively constant diameter from Stage 2 to 4, with increased proportions of R- and B-cells. Biochemical analysis indicated there was a significant increase in total carotenoids in the ovary during maturation. The hepatopancreas, however, had relatively consistent total carotenoid concentrations that were greater than those of the ovary. Overall, the lipid analysis results indicated there were lesser concentrations of fatty acids in the hepatopancreas, while in the ovary there were increasing concentrations during maturation. The lesser concentrations of fatty acids in the hepatopancreas than ovary suggested that energy was transferred to the ovary for future embryonic and larval development. The relationship between the hepatopancreas and the ovary in nutrient content is an important finding in providing a baseline to formulate an optimal diet for improved mud crab hatchery practices.