Abstract

DIAZ, Marina et al. Comer o ser comido: factores que determinan la condición nutricional de larvas de Engraulis anchoita de la población patagónica de la especie. Ecol. austral [online]. 2016, vol.26, n.2, pp.120-133. ISSN 1667-782X.

Eat or be eaten: factors that determine nutritional condition of Engraulis anchoita larvae from patagonian population of the species. The Patagonian population of Engraulis anchoita inhabits the coastal sector comprised between 42° and 46° S. Its spawning and rearing areas are associated with the tidal frontal system of Peninsula Valdés, which forms in late spring and breaks during early autumn. Oceanographic frontal conditions can enhance primary production and zooplankton biomass, representing an enriched food source for fsh larvae. Larval nutritional condition was estimated using three indices: Fulton's Condition Index, RNA/DNA ratio and growth performance. Two oceanographic sections were compared, one in which the presence of the frontal system was observed and another devoid of such effect. Condition indices refected an enhanced nutritional condition of anchovy larvae in the section where the front persisted. Generalized linear models were applied to determine the effect of environmental variables on larval condition. RNA/DNA ratio was considered as the dependent variable, whereas surface chlorophyll concentration, copepod nauplii abundance, jellyfsh volume and larval standard length were used as predictors. In general, the nutritional condition improved with the abundance of copepod nauplii, potential food source for the anchovy larvae. In contrast, the RNA/DNA ratio decreased with the increase of jellyfsh abundance, suggesting that, in the study area, these organisms might act as competitors of anchovy larvae.

Keywords : Anchovy larvae; RNA/DNA ratio; Peninsula Valdés frontal system.