Will marsh restoration in eutrophic ecosystems provide ecosystem services of nitrogen removal and carbon sequestration?
Salt marshes play a critical role in the structure and function of coastal ecosystems, including the reduction of anthropogenic nitrogen (N) loading. Salt marshes have experienced significant declines over the last century, due in part to eutrophication. Large scale salt marsh restoration efforts are common worldwide and are often motivated towards regaining lost ecosystem services such as N removal, carbon (C) sequestration, and mitigation of storm surge. Many restorations are underway in the eutrophic Hudson River estuary (HRE), but it is not clear if restored marshes have the capacity for N removal and C retention in eutrophic environments. In this research, we are measuring how eutrophic conditions alter biogeochemical cycles in urban salt marshes. We are measuring N removal and C retention across a chronosequence of restored salt marshes in Jamaica Bay and the Harlem River to determine the age and environmental conditions under which salt marsh restoration may become an effective strategy for ecosystem services in eutrophic environments. Our results will illustrate how controls on different pathways of N cycling within urban salt marshes may lead to the sustained N availability or promote N removal from the ecosystem.
Understanding the impacts of restored oyster reefs on nitrogen cycling in eutrophic environments
Excess nitrogen (N) inputs to estuaries result in a number of environmental problems, including occurrence of harmful algal blooms and low-oxygen conditions. As one of the most eutrophic estuaries in North America, the Hudson River Estuary (HRE) requires mitigation of N loads. Efforts to improve ecosystem health in the HRE and elsewhere include restoration of habitats such as oyster reefs. Recent studies suggest oyster reefs may enhance N removal (i.e. denitrification), however, we require better understanding of N removal pathways in and surrounding restored reefs in eutrophic environments. Therefore, our work aims to determine if recently restored oyster reefs in NYC will enhance N removal through multiple pathways. We measure N removal via denitrification and oyster filtration and assimilation.