Modelling key variables for understanding the effects of grazing and nutrient recycling by zooplankton on the freshwater microbial loop

Pelagic microbial food webs are structured by zooplankton through grazing and nutrient recycling. Cladocerans copepods assumed to have different effects on the loop prey sizes releasing phosphorus (P) differentially. Here, we assessed this effect of differential recycling dynamics using a combination experimental modelling approaches. We performed field incubation experiments in an oligotrophic mountain lake (north-Patagonian Andes) natural community two dominant taxa: cladoceran (Diaphanosoma chilense) copepod (Boeckella gibbosa). The were separately treatments with direct indirect presence, respectively. built mechanistic model estimate P quotas. was parameterised results from our experiment prior information size-based traits C:P Bayesian approach. Laboratory for excretion also test predictive accuracy model. Our showed that cladocerans contrasting loop. Diaphanosoma chilense grazed mainly picoplankton while B. gibbosa nanoflagellates algae. reduced biomass increased quota picoplankton, nanoflagellates. In contrast, released more P, increasing reducing nanoflagellates, but its quota. Based results, favours higher acquisition rates picoplankton. By would mixed main items quotas strict osmotrophic algae decreasing is useful quantitatively assess key planktonic variables, which usually difficult measure field, such as quotas, conspicuous variables compartments dissolved particulate concentrations. presented here could be used disentangle complex pathways web. relative importance phagotrophy osmotrophy uptake, grazers result understanding ecosystem matter flux resource use efficiency.