Grazing resistance and poor food quality of a widespread mixotroph impair zooplankton secondary production

• DOI: 10.1007/s00442-020-04677-x
• Publication Date: 2020-06-05T20:02:45Z
• Authors: Csaba F. Vad; Claudia Schneider; Dunja Lukić; Zsófia Horváth; Martin J. Kainz; Herwig Stibor; Robert Ptacnik
• Keywords: Mixotroph; Dominance (genetics)

Growing evidence suggests that global climate change promotes the dominance of mixotrophic algae especially in oligotrophic aquatic ecosystems. While theory predicts mixotrophy increases trophic transfer efficiency food webs, deleterious effects some mixotrophs on consumers have also been reported. Here, using a widespread algal genus Dinobryon, we aimed to quantify how colonial taxa contribute secondary production lakes. We, therefore, studied dietary Dinobryon divergens Cladocera (Daphnia longispina) and Copepoda (Eudiaptomus gracilis), representing two main taxonomic functional groups zooplankton. In feeding experiments, showed was largely grazing resistant even inhibited uptake high-quality reference Daphnia. Eudiaptomus could extent compensate with selective feeding, but negative long-term quality effect evident. Besides, more sensitive pure diet than Low lipid content high C:P elemental ratio further supported low nutritional value mixotroph. stable isotope approach analysing natural plankton community, found carbon not conveyed efficiently Our results show increasing can result reduced energy at higher levels. wider perspective, favours detrimental which may constrain pelagic systems, similarly cyanobacteria eutrophic