Ontogenetic development of digestive enzymes and elemental composition of sesarmid crab Episesarma singaporense

Abstract

This work investigates the ontogenetic development of the main digestive enzymes and elemental composition of sesarmid crab Episesarma singaporense. All observed digestive enzyme activity changed significantly with the developmental stages. The lowest pepsin-specific activity appeared in fertilized eggs (FE), then increased dramatically and maintained level during the zoeal stages, and decreased significantly in megalopa and crab I. The highest activity of trypsin and chymotrypsin were observed in FE and crab I, and the trend was increasing with age during zoeal stages. Amylase-specific activity remained about constant from FE until zoea II, dramatically increased from zoea III to zoea IV, and then decreased in the megalopal stage of newly hatched crabs. The lowest lipase-specific activity was in FE and zoea I, but increased dramatically and was maintained during zoea II to zoea IV. Significantly decreased activity was observed in megalopa relative to the maximum value in zoea III, and then the activity was regained in crab I stage. These changes were also associated with elemental composition in terms of carbon (C), hydrogen (H), nitrogen (N) and the C:N ratio. Overall findings from the current study inform about the physiological adaptations during early development, and could support the design of feeding regimens for larviculture of this species.