The Keystone Role of Heterotrophic Microbes in Driving Ecosystem-level Effects of Nutrient Enrichment

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The keystone role of heterotrophic microbes in driving ecosystem-level effects of nutrient enrichment A. D. Rosemond, J. B. Wallace, K. Suberkropp This project builds on a previous nutrient addition to a headwater stream in the southern Appalachian Mountains. This addition resulted in rapid decomposition of terrestrially derived organic matter, enhanced microbial production, especially fungi, and elevated invertebrate productivity. The proposed study is designed to separate the relative importance of fungi and bacteria in detritus-based systems. We will continue to add nutrients and eliminate the fungal component of the microbial community by adding a fungicide to the treatment stream. By greatly reducing fungi we will assess their importance to ecosystem processes such as litter decomposition, overall microbial production and respiration, invertebrate secondary production, suspended particle export, and organic matter storage. Our hypotheses will test the nature, and types of relationships between fungi and bacteria in detritus-based systems, i.e. do fungi and bacteria compete for carbon and nutrients or do they complement each other? This study adds to our understanding the importance of microbial diversity in ecosystem functions.