Coastal Ecosystems: Climate Change and Anthropogenic Impacts

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Salt marshes, grassy meadows flooded by ocean tides, are exceptional carbon sinks as their vegetation fixes carbon dioxide from the atmosphere and stores it in the soil for millennia. My research program will quantify the magnitude of this sink in two Canadian salt marshes. At the same time I will examine the potential for emissions of methane and nitrous oxide, two greenhouse gases that can be emitted from marshes. Emissions of these gases counter the value of stored carbon as they are more potent than carbon dioxide in terms of global warming. By comparing the rates of carbon stored and greenhouse gases emitted we can assess the potential climate feedbacks of salt marshes and how their loss in the past, or future, might affect climate. Ongoing experiments of fertilized marshes will be incorporated into this study to see determine how excess nutrients released to coastal lands and waters will affect gas emissions, thus climate feedbacks. This research will have immediate value to conservation because it will enable us to estimate the value of preventing salt marsh loss or restoring marshes in terms of carbon storage and its climate ramifications. In fact, the carbon stored in salt marshes, called "Blue Carbon", is now being considered for carbon offset programs with expectation that sale of Blue Carbon credits will stimulate preservation and conservation of coastal marshes. However, we have yet to accurately document the amount the amount or rate of carbon stored within an entire marsh. Neither have we performed a comprehensive assessment of the potential for greenhouse gas emissions that could reduce the economic value of the carbon. My research seeks to fill this void by answering the following questions: 1) How do carbon stocks and storage rates vary within a marsh; what are the controls, and what are best predictors of the storage? 3) How much do greenhouse gas emissions vary, what are the controls, and what variables are best predictors of those rates? 4) How does nutrient enrichment affect the storage potential and gas emissions? Answers to these questions will be valuable to planning for coastal management as well.