View/Open - HPS Repository - Arizona State University

22 researchThe High Cost of Coastal LivingUnderstanding West Falmouth Harbor’s Responseto Nitrogen PollutionThe beautiful beaches and harbors of Cape Cod seem to encourage more developmentand more residents each year. MBL Ecosystems Center scientists have found the perfectlaboratory for studying just how costly this popularity may be for the local environment:West Falmouth HarborFor 17 years, the Town of Falmouth’s main wastewater treatment facility has operated inthe West Falmouth Harbor watershed. Nitrogen inputs to the harbor have increased twofoldover the last few years and are expected to increase further over the next three to five yearsas a plume of nitrogen-contaminated groundwater originating from Falmouth’s wastewatertreatment plant reaches the estuary. Wastewater transported through groundwater toestuaries is a major supplier of nitrogen in densely populated watersheds, and contributesto coastal eutrophication, a condition that can cause suffocating algae growth and death ofanimal life from lack of oxygen.To assess the response of West Falmouth Harbor to rapid increases in nitrogen pollution,MBL Ecosystems Center scientists Anne Giblin, Kenneth Foreman, and Jane Tucker, andtheir colleagues from Cornell University and the University of Virginia, are studying themechanisms behind changes in the West Falmouth Harbor ecosystem during differentstages of nitrogen enrichment. The project is funded by a major National ScienceFoundation biocomplexity grant. The whole-ecosystem “experiment” mimics the transitionfrom low to moderate, and ultimately to high, nutrient loading within the ecosystem.“Because the nitrogen inputs [coming from the treatment plant] are well documented, WestFalmouth serves as a model system to study how internal nitrogen processing is altered byincreasing nitrogen pollution,” says GiblinThe scientists working on the study hypothesize that West Falmouth Harbor will respondto nitrogen pollution in phases. As wastewater inputs of nitrogen begin to increase,they expect that nitrogen fixation—the process by which bacteria convert nitrogen gasfrom the air into forms that can be used by plants and animals—will be reduced. But atthe same time, the loss of nitrogen from the system through another bacterial process(denitrification) may increase. As a result, during the early stages of nitrogen pollution inWest Falmouth Harbor, plants and animals within the ecosystems may show only a modestresponse to the contaminated groundwater generated by the plume. “In West Falmouththere has been some eel grass loss but there are large areas of the harbor where eel grassremains,” says Giblin.