Gross growth efficiencies of protozoan and metazoan zooplankton and their dependence on food concentration, predator-prey weight ratio, and taxonomic group

Abstract

A comprehensive dataset on the gross growth efficiency (GGE) of planktonic protozoans and metazoans was gathered from the literature in order to (1) identify typical ranges of values, (2) to reexamine the taxon specificity of GGE, and (3) to evaluate the impact of food concentration, predator-prey weight ratio, and temperature on GGE. All taxa (i.e. nano/microflagellates, dinoflagellates, ciliates, rotifers, cladocerans, and copepods) were found to have mean and median GGE of ~20-30%. Contrary to the common practice of using different values of GGE for ciliates and crustaceans, I found that the GGE hardly differed between taxa. Variability within all taxa was high and could only partially be attributed to the independent variables mentioned above. The dependency of GGE on food concentrations was the most reliable relationship identified by multiple regression. Establishing further generalizations regarding the dependency of GGE on other factors was hampered by methodological differences among studies and taxa and the lack of information on other potentially important factors such as the elemental composition of prey items. Future studies of GGE should recognize the importance of these factors.