ABSTRACT: Marl lakes often have microbialite crusts in the littoral zone, containing a community of cyanobacteria and algae. Previous work has shown that these crusts are most prevalent in oligotrophic lakes and that crust metrics, such as chlorophyll content and green algal abundance, are correlated with total phosphorus concentration (TP) in lake waters, with no intact crusts being found when mean TP > 0.02 mg l^-1. Two experiments were carried out to examine how microbialite crust communities respond to nutrient pollution. A culture experiment exposed crusts to various concentrations of nutrients and measured responses over a 43 wk period. In a parallel controlled field experiment, crusts were moved between areas of different trophic state within Lough Carra, a marl lake in the west of Ireland, to see how the community responded. In both experiments, increased nutrient conditions caused a change in relative abundances of taxa in the crust community, leading to a dominance of green algae and degradation of crusts. There were significant differences in chlorophyll concentrations between crusts grown in different nutrient environments. It was concluded that these metrics offer the prospect of a useful quality assessment method for marl lakes.

中文翻译：

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营养污染使爱尔兰马尔湖Lough Carra的微生物分解

摘要：Marl湖泊在沿海地区经常有微双辉石结壳，包含蓝藻和藻类群落。先前的研究表明，这些硬皮在贫营养湖泊中最为普遍，并且硬皮指标（例如叶绿素含量和绿色藻类丰度）与湖水中的总磷浓度（TP）相关，当平均TP>>时，没有发现完整的硬皮。 0.02毫克l ^-1。进行了两个实验，以检验微生物岩地壳群落对养分污染的响应。一项培养实验将地壳暴露于各种浓度的营养物质，并在43周内测量了响应。在一个平行的受控野外实验中，地壳在爱尔兰西部的一个沼泽湖拉夫卡拉内部不同营养状态的区域之间移动，以观察社区的反应。在这两个实验中，营养条件的增加导致地壳群落中分类单元的相对丰度发生了变化，从而导致了绿藻的优势地位和地壳的降解。在不同营养环境下生长的硬皮之间叶绿素浓度存在显着差异。得出的结论是，这些指标为泥灰湖提供了一种有用的质量评估方法的前景。