Trophic Cascades and Interacting Control Processes in a Detritus-Based Aquatic Ecosystem

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Human activity is changing local and global environments at unprecedented rates. Some of the most significant changes involve widespread nutrient enrichment and changes in species composition as well as global warming and sea level rise. Predicting the effects of these multiple stresses is particularly important in coastal salt marshes because they are among the most biologically productive areas in the world and are heavily used by humans for a variety of purposes. Coastal areas are now experiencing changes in nutrient loading, species composition and sea level rise 5-10 fold higher than measured over the last century. This project addresses the question: Over the long run, how will an increase in nutrients interact with changes in species composition to alter coastal ecosystem structure and function? We will conduct field experiments in which salt marsh ecosystems are altered by addition of nutrients and by removal of an abundant and important fish, the mummichog. We will follow the effects of these manipulations on the food web and nutrient cycles for four years. The experiments will be linked to a model that can be used to predict the saltmarsh response over decades. The results of this research will be useful to managers who are faced daily with resolving the conflicts among the many ways that humans use coastal regions.