ABSTRACT: Shallow lakes are complex environments that play an important role in ecology. Their relationships with the surrounding areas make these lentic water bodies susceptible to alterations in response to human activity. For example, the input of polyphenols could be critical in altering species interactions. The shallow lakes located in the pampean plain of Argentina are major reservoirs of diversity, with the environmental habitats of the Salado River basin in particular having become impacted by human activities. The aim of this work was to evaluate the effects of different polyphenol concentrations (i.e. tannins) on changes in the plankton assemblages and on the abundance of bacteria in San Miguel del Monte Lake. Factorial experiments under laboratory conditions (4 tannin concentration levels and 4 response times) revealed that high tannin concentrations affected neither the phyto- and zooplankton assemblages nor bacterial abundances. Major changes both in assemblages and in the bacterioplankton abundances were dependent on exposure time. We found that the initial food web of grazers shifted to detritivorous feeding, thus producing a simplification of the community toward early succession. Although no effects of polyphenols were registered here, what proved striking was the resilience of the system and the capability to support high tannin concentrations throughout the experiment. Therefore, future investigations are necessary to elucidate the key role of such humic substances in the structuring of plankton assemblages of shallow lakes from strongly impacted areas, such as those found in the pampean region.

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多酚对庞氏浅湖浮游生物组成和细菌丰度的影响：实验研究

摘要：浅湖是在生态中起着重要作用的复杂环境。它们与周围地区的关系使这些胶体水体易于响应人类活动而发生变化。例如，多酚的输入对于改变物种相互作用可能至关重要。位于阿根廷高原平原上的浅湖是主要的生物多样性储集区，尤其是萨拉多河流域的环境栖息地已受到人类活动的影响。这项工作的目的是评估圣米格尔德尔蒙特湖中不同浓度的多酚（即单宁酸）对浮游生物组成的变化和细菌含量的影响。在实验室条件下的析因实验（4种单宁浓度水平和4个响应时间）表明，高单宁浓度既不影响浮游植物和浮游动物的组合，也不影响细菌的丰度。组装和浮游细菌丰度的重大变化均取决于暴露时间。我们发现，放牧者的最初食物网转移到有害的饲料上，从而简化了社区朝着早期继承的方向发展。尽管此处未发现多酚的作用，但令人惊讶的是该系统的弹性以及在整个实验过程中支持高单宁浓度的能力。因此，