Food nutrient availability affects epibiont prevalence and richness in natural Daphnia populations

Abstract

The increased input of nutrients into biological systems has been shown to result in altered biotic interactions through changes in food availability. The aim of this study was to test for an association between phytoplankton nutrient content and epibiont variables in natural zooplankton populations. Via a field survey, we studied how a gradient in food quantity and quality impacted host population density and epibiont variables in Daphnia pulex. We found a significant decrease in epibiont prevalence and infracommunity richness, which could mainly be attributed to a changing phytoplankton N : P ratio (caused by P-limitation). We performed a lab experiment in which we exposed Daphnia magna to different algal nutrient ratios and the epibionts detected in the field study. P-limitation in the algae affected D. magna performance and resulted in similar trends of food quality effects in the epibiont variables. The experiment, however, also reflected subtle differences between different epibiont species.

Physiological and nutritional constraints on zooplankton productivity due to eutrophication and climate change predicted using a resource-based modeling approach

“…Differences between field and lab derived growth rates may also be due to competition and predation experienced in natural environments (Reyserhove et al 2020).…”