Temporal variation of the larval diet of Bregmaceros bathymaster (Pisces: Bregmacerotidae) along the coast of Jalisco and Colima, Mexico, during one annual cycle (1996).

Abstract

Temporal variations in the larval diet of Bregmaceros bathymaster on the coast of Jalisco and Colima during 1996 were analyzed. An increase in feeding incidence (from 10% in preflexion stage to 80% in transformation stage), in trophic spectrum (from 10 to 20 prey items), and in prey size (from 0.15 to 0.45 mm) was observed in relation to larval development. The index of relative importance showed that copepods in different stages of development dominated the larval diet with >80% of the total prey in preflexion larvae (nauplii and calanoids) and >60% in larvae in transformation (Euterpina spp. and calanoids). The Morisita index defined three groups of sampling stations based on larval diet and zooplankton environment. In the winter group, calanoid copepods, Euterpina spp., and Subeucalanus spp. dominated the diet, coinciding with the predominance of copepods in the environment. In the spring group, the cladoceran Penilia avirostris and ostracods dominated the diet and the zooplankton. In the summer/autumn group, calanoid copepods, Acrocalanus spp., and ostracods dominated the diet, whereas ostracods and copepods dominated the zooplankton. The results indicate that the temporal changes in the larval diet of B. bathymaster are associated with the variation in zooplankton, corresponding to three climate periods that affect the study area.