Nutrient enrichment of coastal-zone waters is of increasing societal concern due to the importance of these waters to people and economies. The goal of this project is to understand how increased amounts of nutrients from land change the numbers and types of nitrogen-processing bacteria in salt marshes. There are two primary scientific objectives. First, a new, rapid, high-resolution technique for sequencing selected bacterial genes ? the DNA tag method ? will be tested to see if it works in salt-marsh sediments. Second, specific analyses of bacterial genes that are a vital part of the nitrogen cycle will be quantified to determine if microbial communities change significantly in response to two years of fertilization with nitrogen. Human impacts on coastal waters are altering marshes and estuaries and affecting the services they provide to society, such as areas for recreation and as nursery grounds for commercially important fish and shellfish. Salt marshes cleanse waters of human-derived nutrients before rivers and groundwaters reach estuaries, and in this way help prevent nutrient overload or eutrophication. These cleansing activities are mediated by bacteria in the sediments. Despite their importance, bacteria in these sediments, and human-induced changes in bacterial communities, are little known. This project will provide information on promising new techniques and on ways bacteria change as a result of human activities.
