Reproductive patterns of the black starry sea urchin Arbacia stellata in Punta Banda, Baja California, Mexico

Abstract

AbstractWidely distributed species such asArbacia stellataadjust patterns of their life history according to local conditions. In the present study the reproductive cycle of this species was analysed throughout a sampling year. Gonadal development cycle, sex ratio, actual fecundity and oocyte size distribution were characterized and the relationship of these reproductive characteristics with environmental variables such as sea surface temperature, photoperiod, chlorophyllaand net primary production evaluated. Our results showed thatA. stellatais a gonochoric sea urchin. Gametogenesis was classified into six stages for both sexes (immature, growth, pre-maturity I, pre-maturity II, mature and spawning) and no synchrony was observed for the gonads between individuals. The female to male ratio was close to 1:1 in most months. The gonadosomatic index (GSI) showed significant differences between sexes or months; however, the highest values were observed during spring, with positive correlation with chlorophylla. No significant differences were observed in the maturity index (MI) between sexes, with a positive correlation with temperature but negative with chlorophyll. Actual fecundity showed wide variations throughout the year and correlation with chlorophyllaand temperature. Oocyte size distribution was unimodal and the predominant frequency was that of mature oocytes. The reproductive cycle ofA. stellatahas a semi-continuous pattern for both sexes and partial spawning throughout the year in the sampling site. We observed nutrient assimilation in the gonads during spring and a larger reproductive activity from late summer to early winter.