Phytoplankton Blooms "Like It Colorful"(BLIC) - The relative influence of biodiversity and biotic interactions on the early stages of phytoplankton bloom formation

全球生物多样性的丧失在水生生态系统中也很明显。生物多样性是如何影响生态系统功能的，从机制上来说，人们只了解了一部分。这种生物多样性-生态系统功能关系已经在初级生产者、浮游植物和浮游植物的初级生产者一级得到了记录。浮游植物参与了全球约50%的初级生产量，基本上控制着全球重要元素的循环，是渔业等重要生态系统服务的基础。浮游植物的特点是具有特殊的动态，能够快速积累大量的生物量。这些所谓的浮游植物水华通常可以定期发生(例如，在春季，即所谓的春季水华)，为更高的营养水平提供重要的食物，或者可以由外部因素(例如，外部营养供应、富营养化)触发。浮游植物水华通常由一个或几个物种支持；对于有毒或可食性差的物种，水华可能会对食物网中的能量和物质转移产生重大的负面影响。一个基本上只从理论上研究的问题是，浮游植物群落的多样性是否对浮游植物水华的形成有影响。随着多样性的增加，群落中有一个物种能够垄断资源并形成水华的概率更高(选择效应)。与此同时，随着多样性的增加，资源利用的互补性和效率可能会增加，垄断资源变得越来越困难(互补效应)。BLIC正在使用一种机械放大的方法来调查这个问题。在受控的实验室实验中，日益多样化的群落暴露在营养脉冲中，选择效应和互补性的强度被量化。下一步，受多样性操控的田间群落将暴露在营养脉冲下，并调查多样性的变化在多大程度上使水华更有可能发生。最后，计划对自然多样性梯度上的自然浮游植物群落进行中游实验。所有实验都将以同样的方式在海洋和淡水实验室和野外社区进行。除了实验方法，BLIC的第二个支柱是对这些研究问题的理论模型分析。基于所谓“特征”的多维数学模型将详细分析浮游植物水华的早期阶段。这些模型将从实验中获得重要的参数，同时对个别实验的执行有重要影响，然后可以详细地研究由该模型产生的特别有趣的环境组合。

The global loss of biodiversity is also visible in aquatic ecosystems. How biodiversity affects ecosystem functions is mechanistically only partially understood. Such biodiversity - ecosystem function relationships are already documented at the level of primary producers; phytoplankton in pelagic systems. Phytoplankton is involved in about 50% of the global primary production, essentially controls global cycles of important elements and is the basis of important ecosystem services such as fisheries. Phytoplankton is characterized by a special dynamic, the ability to quickly accumulate large amounts of biomass. These so-called phytoplankton blooms can often occur on a regular basis (e.g., in spring, so-called spring blooms) and provide important food for higher trophic levels, or can be triggered by external factors (e.g., external nutrient supply, eutrophication). Phytoplankton blooms are usually supported by one or a few species; in the case of toxic or poorly edible species, blooms can have significant negative effects on the transfer of energy and matter in food webs. A question that has been studied essentially only theoretically is whether the diversity of phytoplankton communities has an impact on the formation of phytoplankton blooms. With increasing diversity, the probability that there is a species in the community that can monopolize resources and form blooms is higher (selection effect). At the same time, as diversity increases, complementarity and efficiency of resource use may increase, and it becomes increasingly difficult to monopolize resources (complementarity effect). BLIC is investigating this issue using a mechanistic up-scaling approach. In controlled laboratory experiments, increasingly diverse communities are exposed to nutrient pulses and the strength of selection effects and complementarity are quantified. In a next step, diversity-manipulated field communities will be exposed to nutrient pulses and investigated to what extent the change in diversity makes blooms more likely or not. Finally, mesocosm experiments are planned with natural phytoplankton communities along natural diversity gradients. All experiments will take place in the same way with marine and freshwater laboratory and field communities. Besides experimental approaches, the second pillar of BLIC is the theoretical model analysis of these research questions. So-called "trait" based multidimensional mathematical models will analyse in detail the early stages of phytoplankton blooms. The models will receive important parameterizations from the experiments and at the same time have an important influence on the execution of individual experiments, which can then investigate particularly interesting environmental combinations for bloom formation arising from the model in detail.