Zooplankton Energy Turnover in a Changing Environment (ZET-Change)

• Applicant: Dr. Natalie Loick-Wilde
• Subject Area: Ecology and Biodiversity of Animals and Ecosystems, Organismic Interactions ; Animal Physiology and Biochemistry
• Term: from 2013 to 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 253351799

Changing nitrogen and carbon biogeochemical cycles as a consequence of climate change and anthropogenic eutrophication alter marine food webs of coastal areas in an unpredictable way. These changes often manifest in the dramatic shift from nutritious algae species to lipid-poor, harmful cyanobacteria blooms that may endanger current food webs including fisheries. So far we don’t have a mechanistic understanding how lower trophic levels like zooplankton cope with such lipid-poor conditions. Zooplankton organisms play a key role in the biological productivity of the ocean as they refine algae into protein- and lipid-rich food and thus link primary to fishery production while fueling the microbial loop with their exometabolomic waste products. This ecosystem function of zooplankton may be profoundly disturbed by spreading cyanobacteria blooms because zooplankton organisms rely on a protein based metabolism only in the nutrient poor tropical ocean, while beyond the tropics they principally metabolize lipids.Previous compound-specific stable isotope work of my colleagues and me on zooplankton samples from the Baltic Sea and tropical North Atlantic proved that the understudied and generally as invariant considered amino acid pool in zooplankton rapidly changes when food concentrations are low, which challenges the current use of bulk C:N ratios as lipid: protein indicator in biogeochemical models, which we discuss in an article for the interdisciplinary journal Ecology. Our work shows that amino acids are a sensitive parameter to investigate the impact of food quality on the energy metabolism in marine food webs. In the ZET-Change Projekt this approach will be expanded to quantify the carbon and nitrogen flows through the amino acid and lipid pools of zooplankton species and communities during annual summer-time cyanobacteria blooms using the Baltic Sea as model ecosystem. We hypothesize that amino acid metabolism plays a significant role in supporting zooplankton production in the Baltic Sea, and that this process is modulated by lipid-poor conditions as found during cyanobacteria blooms and during times of low food particle concentrations. The effect on the population and ecosystem level will be tackled by exploring the exometabolomic waste product release and the flow of nitrogen and carbon into copepod eggs in combined field sampling and ship based experiments and subsequent analysis using cutting edge technologies like nanometer scale secondary ion mass spectrometry and Fourier transform ion cyclotron resonance mass spectrometry. The combination of a strong field program with a multiple method approach will place our work in a broader, basin-scale context and allow us to establish a mechanistic understanding of the role of an amino acid (a.k.a. protein) based metabolism in zooplankton during cyanobacteria blooms.

• DFG Programme: Research Grants
• Major Instrumentation: Gaschromatographie-Verbrennungssystem
• Instrumentation Group: 1700 Massenspektrometer