Growth of Odonthestes bonariensis larvae feeding on suboptimal zooplankton densities

HORACIO ZAGARESE

ENVIRONMENTAL BIOLOGY OF FISHES

Año: 1996 vol. 45 p. 191 - 198

0378-1909

In this study we investigate the effect of food availability (zooplankton biomass) on the growth of Odontesthesbonariensis (Atherinidae) larvae . The larvae were stocked in four 45 mz outdoor tanks at relatively highdensities (100 and 200 larvae M-2) . Because of the high stocking densities, the zooplankton biomass was depletedin all tanks. However, the patterns of food limitation, and particularly periods of severe food shortage,differed in tanks stocked at different densities . We could therefore, observe the effect of food limitation inlarvae that differed in weight and age . The effects of variables suspected to influence O. bonariensis growthrates (age and weight of larvae, available zooplankton biomass, mean individual weight of available preys,total ingested prey weight, and mean weight of ingested preys) were investigated using standard multipleregression methods, and a model assuming : (1) an allometric relationship between maximum growth rates andweight of larvae, and (2) an inverse relationship between growth depression and the available zooplanktonbiomass. Both methods were consistent in showing that only the weight of larvae, and the availability ofzooplankton prey had significant effects on the growth of O . bonariensis. The model's results additionallysuggest that, if the observed growth rates are scaled by the maximum growth rate corresponding to the larvaweight, the effect of zooplankton biomass is largely independent of age and weight of larvae .