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Seasonal effect on the gonadal development and biochemical composition in the sea urchin Echinometra lucunter lucunter (Echinodermata: Echinometridae) from Lobos Islet, Venezuela

Abstract:

Fresh roes of rock-boring urchin sea Echinometra lucunter lucunter has a high food value, which enhances its fishery and mariculture; however, biochemical composition and development are influenced by environmental conditions. To evaluate protein, lipid, and carbohydrate content, and be able to establish how it varies the storage in the gonads during upwelling (high primary productivity/22-24°C) and stratification (low primary productivity/28-30°C) seasons, adult sea-urchins (> 30 mm) were monthly collected from Lobos Islet (Venezuela). Salinity, temperature, dissolved oxygen, transparency, total seston and chlorophyll a in superficial seawater were averaged. Biometric parameters, sex, reproductive stage, gonadosomatic index (GI), and biomolecule content in the gonads were determined per individual. Gonadal development of E. lucunter lucunter occurs during the upwelling-stratification transition, corresponding with the seawater temperature increase. Biomolecules showed temporal variations associated with gonadal production; a negative relationship existed between the preferential use of carbohydrates and lipids. Maximal gonad production and accumulated carbohydrate and protein were reached during stratification; however, during upwelling synchronized spawns were observed as well as a respective decrease in lipids and carbohydrates. The environmental conditions during stratification stimulate the gonadal development of E. lucunter lucunter, in comparison the coastal upwelling acts as a trigger of synchronized spawning for both sexes. The energy biomolecules are stored in the roes mainly during stratification, using with preference to carbohydrates to metabolic demand.