Bacteria-zooplankton interactions: a key to understanding bacterial dynamics and biogeochemical processes in lakes?

在世界范围内，后生浮游动物代表了远洋系统中巨大的表面和生物量，但它们与细菌的联系被认为是相当间接的（通过营养循环和营养级联）。然而，动物园动物的身体携带着大量的不同细菌，这可以解释浮游细菌的相当大的比例和多样性。浮游动物体内是富含有机物的微环境，支持细菌快速生长。它们的物理化学条件与周围的水不同，因此选择不同的细菌群落。到目前为止，关于细菌-浮游动物相互作用的信息仍然只限于少数浮游动物群体和环境，特别是沿海和河口沃茨的桡足类。因此，我们的建议集中在湖泊中的细菌浮游动物的相互作用。由于浮游动物类群可以有非常不同的生活史特征，我们将比较大量的浮游动物类群在各种湖泊。在现场和实验室研究中，我们将以高空间和时间分辨率研究这些相互作用。我们将讨论4个主题：A）细菌-浮游动物组合的时空变化，B）浮游动物肠道微生境中的微生物动力学，C）浮游动物迁移对细菌的扩散，D）仲夏浮游动物减少对微生物活动的影响。我们的目标是从根本上改变我们理解浮游食物网和细菌后生动物相互作用的生态作用的方式。

Worldwide, metazoan zooplankton represents an enormous surface and biomass in pelagic systems but their linkage with bacteria has been assumed to be rather indirect (via nutrient cycling and trophic cascades). However, a zooplankter’s body carries a high abundance of diverse bacteria, which can account for a substantial fraction and diversity of pelagic bacteria. Zooplankton bodies are organic-rich micro-environments that support fast bacterial growth. Their physical-chemical conditions differ from those in the surrounding water and hence select for different bacterial communities. Until now, information on bacteria- zooplankton interactions is still limited to only a few zooplankton groups and environments, in particular copepods in coastal and estuarine waters. Therefore, our proposal focuses on bacteria-zooplankton interactions in lakes. Since zooplankton taxa can have very different life history traits we will compare a large number of zooplankton taxa in a variety of lakes. In field and lab studies we will investigate these interactions with a high spatial and temporal resolution. We will address 4 topics: A) spatial and temporal variations in bacteria-zooplankton association, B) microbial dynamics in the zooplankton gut microhabitat, C) bacterial dispersal by migrating zooplankton and D) effects on microbial activities during the mid-summer zooplankton decline. We aim to fundamentally change the way we understand pelagic food webs and the ecological role of bacteria-metazoan interactions.