Molecular and organismal ecology of aquatic hyphomycetes

需要新的方法来更好地了解真菌如何促进溪流中植物物质的分解，以及污染和其他人为变化对这一过程的影响。我的研究计划通过应用分子技术来表征真菌及其活动来解决这个问题。河流社区严重依赖进口植物材料作为能源和食物。多达90%以秋天落叶的形式落入溪流。这些叶子不能作为食物，除非它们被微生物定植，微生物会提高碎屑中的氮含量，并将植物的结构多糖（纤维素、半纤维素）分解成可以被无脊椎动物消化的亚基。因此，微生物分解是初级生产者（通过释放营养物质）和无脊椎动物消费者（通过调节碎屑）的关键过程。在大多数溪流中，一种特殊的真菌，即水生菌丝，主导着树叶的分解。它们的生物量占碎屑叶质量的20%，每溪流面积的真菌年产量与细菌和大型无脊椎动物的产量相同。以过程为导向的分解方法对于估计初级生产者和上层营养水平的可用性非常重要，并且已经提出了腐烂率的标准化测量方法作为评估功能流完整性的标准。然而，生物多样性研究表明，为了理解和潜在地预测生态系统对环境变化的响应，这些功能方面必须有结构（分类学）信息的补充。拟议的研究计划将确定树叶分解的主要参与者并估计他们的贡献。除了水生真菌，我们还将考虑其他微生物群，如壶菌、卵菌和细菌。将评估这些群体对人为变化（温度、富营养化、重金属污染）的反应。

There is a need for new approaches to better understand how fungi contribute to decomposition of plant matter in streams, and the impact that pollution and other anthropogenic changes have on this process. My research program tackles this problem by applying molecular techniques to characterize fungi and their activities.Stream communities depend heavily on imported plant material for energy and food. As much as 90 % can be in the form of autumn-shed leaves falling into streams. These leaves are not acceptable as food until they have been colonized by microorganisms, which raises the nitrogen level of the detritus and breaks down the plant's structural polysaccharides (cellulose, hemiculoses) into subunits that can be digested by invertebrates. Microbial decomposition is thus a key process for primary producers (through release of nutrients) and invertebrate consumers (through conditioning of detritus). In most streams, a specialized group of fungi, the aquatic hyphomycetes, dominate the decomposition of leaves. Their biomass accounts for up to 20% of detrital leaf mass and fungal annual production per stream area is of the same order of magnitude as that of bacteria and macroinvertebrates. A process-oriented approach to decomposition is important for estimates of what will be available for primary producers and upper trophic levels, and standardized measures of decay rates have been proposed as criteria to assess functional stream integrity. Biodiversity studies suggest, however, that these functional aspects have to be complemented by structural (taxonomic) information for understanding and potentially predicting ecosystem responses to environmental change. The proposed research program will identify the main participants in leaf decomposition and estimate their contributions. In addition to aquatic fungi, we will consider other microbial groups such as Chytrids, Oomycetes and Bacteria. Responses of these groups to anthropogenic change (temperature, eutrophication, heavy metal pollution) will be evaluated.