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

气候变化和人为富营养化导致的氮和碳生物地球化学循环的变化以一种不可预测的方式改变了沿海地区的海洋食物网。这些变化往往表现为从营养丰富的藻类物种向缺乏脂质、有害的蓝藻水华的戏剧性转变，这可能会危及当前的食物网，包括渔业。到目前为止，我们还没有一个机制来理解像浮游动物这样的低营养水平是如何应对这种缺乏脂肪的条件的。浮游动物生物在海洋的生物生产力中发挥着关键作用，因为它们将藻类提炼成富含蛋白质和脂肪的食物，从而将主要与渔业生产联系起来，同时用其代谢外废物为微生物循环提供燃料。浮游动物的这种生态系统功能可能会受到蓝藻水华传播的严重干扰，因为浮游动物只在营养不良的热带海洋依赖基于蛋白质的新陈代谢，而在热带以外，它们主要代谢脂肪。我和我的同事以前对波罗的海和热带北大西洋的浮游动物样本进行的特定化合物稳定同位素研究证明，当食物浓度较低时，浮游动物中未被研究且通常被认为是不变的氨基酸池会迅速变化，这对目前在生物地球化学模型中使用整体C：N比作为脂：蛋白质指示剂提出了挑战，我们在跨学科期刊《生态学》上的一篇文章中讨论了这一点。我们的工作表明，氨基酸是研究食物质量对海洋食物网中能量代谢的影响的一个敏感参数。在Zet-Change项目中，这一方法将扩展到以波罗的海为模式生态系统，量化每年夏季蓝藻水华期间通过浮游动物物种和群落的氨基酸和脂水池的碳和氮流动。我们假设氨基酸代谢在支持波罗的海浮游动物生产方面发挥着重要作用，并且这一过程受到蓝藻水华和食物颗粒低浓度时期缺乏脂肪的条件的调节。对种群和生态系统水平的影响将通过在野外采样和船载实验相结合的方式探索外代谢废物的释放以及氮和碳流入桡足虫卵，并随后使用纳米级二次离子质谱仪和傅立叶变换离子回旋共振质谱仪等尖端技术进行分析来解决。一个强大的实地项目与多方法方法的结合将把我们的工作置于更广泛的盆地规模的背景下，并使我们能够建立对氨基酸(又名。蓝藻水华期间浮游动物基于蛋白质的代谢。

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.