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Using Nitrogen Stable Isotope Tracers to Track Climate Change Impacts on Coastal Salt Marshes
Citation:
Oczkowski, A., C. Wigand, E. Watson, Alana Hanson, AND E. Markham. Using Nitrogen Stable Isotope Tracers to Track Climate Change Impacts on Coastal Salt Marshes. Presented at Coastal and Estuarine Research Federation (CERF) 22nd Biennial Conference, San Diego, CA, November 03 - 07, 2013.
Impact/Purpose:
Climate change is expected to change precipitation pattern in the northeast U.S., where there will be more extreme storms and longer periods of drought. This will change the timing and delivery of water to sensitive coastal salt marshes and estuaries. This work presents the results of multiple-stressor experiments focused on the potential impacts of climate change associated alterations in precipitation patterns, sea level rise, and increasing anthropogenic nutrient inputs to coastal salt marshes. We found that, in the future, it is likely that salt marshes will be less efficient at intercepting and retaining nutrients before they reach downstream estuaries.
Description:
Climate change impacts on coastal salt marshes are predicted to be complex and multi-faceted. In addition to rising sea level and warmer water temperatures, regional precipitation patterns are also expected to change. At least in the Northeast and Mid-Atlantic U.S., more severe storms and longer droughts are predicted. As the ecological community is gaining a better understanding of how individual factors may impact salt marsh communities, we conducted experimental work to examine at how the combination of sea level rise, precipitation changes, and variations in nutrient loading may stress the salt marshes. These multiple stressor experiments are complicated and data rich but nitrogen stable isotope (δ15N) tracers have proven to be a valuable tool in unraveling some of the complexities—particularly those that don’t present clearly in measured physical parameters (aboveground biomass, plant height, etc.). By adding δ15N enriched in the heavy isotope (15N), we can quantify how efficiently nitrogen is taken up by the system and how it is allocated by plants. Our results from multiple mesocosm experiments and an in-situ salt marsh organ experiment indicate that climate change will decrease the ability of coastal salt marshes to intercept and retain nutrients before they reach sensitive coastal waters.