Gonadal and molecular indices in the sea-urchin Lytechinus variegatus (Echinoidea: from Cariaco Gulf, Venezuela

Active extraction of sea -urchin Lytechinus variegatus from the northeast of Venezuela could cause a reduction in the populational density. Therefore, knowledge about somatic growth and gonadal production is relevant for the rational exploitation and sustainable management of sea -urchin populations. During an annual cycle, this study examined the reproductive biology and growth molecular indices (RNA:DNA and Protein:DNA) of a population of L. variegatus sea -urchin from Cariaco Gulf (Venezuela); a marine ecosystem influenced by the seasons of stratification and coastal upwelling. Sea -urchin population was composed of homogeneous sizes, with significant increase of the total fresh mass (MF) and gonadosomatic index (IG) during stratification. Significant regression models were obtained during upwelling and stratification periods, particularly among the MF with testa dimensions and Aristotle's lantern. Gonadal development was continuous, showing partial spawning during the upwelling period. RNA:DNA ratio increased during stratification season, but not Protein:DNA index. Principal Component Analysis indicated association among molecular growth indices with seston, conversely to phytoplankton biomass, and seawater surface temperature. Reproductive cycle of L. variegatus presented a seasonal pattern associated with temperature and primary productivity; particularly during upwelling it actively spawns, and the gametogenesis is enhanced during stratification, when the metabolic processes are greater.