Alternative states of a simple predator-prey system induced by competition between small edible and large inedible algae and fungal parasitism (APPS)

由小型可食用藻类和大型不可食用藻类之间的竞争以及真菌寄生引起的简单捕食者-猎物系统的替代状态（APPS）

• 批准号: 394716440
• 负责人: Professor Dr. Hans-Peter Grossart
• 金额: --
• 依托单位: Abteilung 3: Plankton- und mikrobielle Ökologie
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/394716440?language=en
• 关键词: Alternative; states; simple; predator; prey

In the presence of grazers, phytoplankton communities often shift to dominance of large inedible algae, limiting energy flow up the grazing chain. This can be counteracted by parasitic fungi (e.g. chytrids), which can infect large algae and make them available to zooplankton grazing (e.g. micro- and macrozooplankton) via zoospores. This so-called “Mycoloop” has profound consequences for food web interactions. In the absence of a feeding link between zooplankton grazers and fungi, parasitic fungi are able to reduce large algae, thereby favouring edible green algae. However, in the presence of a strong feeding link from fungi to zooplankton may even foster inedible algae through decreased infection rates. Trait variability in the host population may enable shifts to more resistant genotypes, decreasing the direct top-down control on inedible algae and weakening the grazer-fungi link. We aim to link trait variability, zooplankton grazing and fungal parasitism to investigate host-parasite/predator-prey interactions and competition of edible vs. inedible phytoplankton in the presence of either fungal parasitism or grazing and in combination. We hypothesize that fungal parasitism has the potential to shift our model system into different alternative states with dominance of either edible or inedible phytoplankton, modulated by the strength of the fungi-zooplankton link. We want to experimentally test the effect of fungal parasitism and the strength of the mycoloop on food web dynamics. We expect the strength of the positive feedback loop on large inedible algae to be dependent on the strength of the grazer-fungi link and on grazer identity. We expect the link to be strongest for selective grazers (copepods) compared to unselective grazers (daphnids). Theoretical investigations of a corresponding food web model will give insights on how different drivers and interaction strength affect competition between small well edible and large inedible algae. In combination, this will enable to determine how fungal parasitism modulates food web dynamics and its implications for phytoplankton diversity and functionality.

在食草动物存在的情况下，浮游植物群落常常转向大型不可食用藻类的主导地位，从而限制了放牧链上的能量流动，这可以通过寄生真菌（例如壶菌）来抵消，寄生真菌可以感染大型藻类并使它们可供浮游动物吃草。例如，通过游动孢子的微型和大型浮游动物），这种所谓的“Mycoloop”对人类具有深远的影响。在浮游动物和真菌之间缺乏摄食联系的情况下，寄生真菌能够减少大型藻类，从而有利于可食用的绿藻，然而，在真菌与浮游动物之间存在强大的摄食联系的情况下，寄生真菌甚至可能培育不可食用的藻类。通过降低宿主群体的感染率来控制藻类可能会转变为更具抵抗力的基因型，从而减少对不可食用藻类的直接自上而下的控制并削弱其能力。我们的目标是将性状变异、浮游动物放牧和真菌寄生联系起来，以研究寄主-寄生虫/捕食者-猎物之间的相互作用以及在真菌寄生或放牧以及真菌组合存在的情况下可食用浮游植物与不可食用浮游植物的竞争。寄生有可能将我们的模型系统转变为不同的替代状态，以可食用或不可食用的浮游植物为主，我们希望通过实验来测试真菌寄生和真菌环对食物网动态的影响，我们预计大型不可食用藻类的正反馈环的强度取决于食草动物与真菌之间联系的强度以及食草动物的身份，我们预计与非选择性食草动物相比，选择性食草动物（桡足类）的联系最强。 （水蚤）相应的食物网模型的理论研究将深入了解不同的驱动因素和相互作用强度竞争如何影响小型可食用藻类和大型不可食用藻类，这将有助于确定真菌寄生如何调节食物网动态及其。对浮游植物多样性和功能的影响。