Role of SAV in estuarine inorganic carbon cycling

Accurate climate prediction requires a detailed understanding of the global carbon cycle. A key carbon cycle feature is the transport of carbon from land to the open ocean. Before reaching the ocean, carbon carried by rivers passes through estuaries, where significant transformations take place. Many of these transformations are mediated by living organisms, such as oysters, clams, salt marshes, mangroves, and seagrasses. However, these “macrobiota” are generally ignored in models of carbon transformations in estuaries. This project aims to advance our understanding of the role that macrobiota play in estuarine carbon dynamics and, ultimately, the large-scale marine cycles of carbon.

Our lab’s role is to measure alkalinity fluxes in SAV beds in the York and Potomac Rivers using incubation chambers deployed in the field. We know that SAV and seagrasses are “blue carbon” ecosystems because the plant material they grow by taking up carbon dioxide during photosynthesis is often buried and stored as organic carbon in the underlying sediments. Therefore, they sequester carbon. However, we know much less about how the plants affect alkalinity, or the buffering capacity of the water. Since alkalinity can affect how much carbon dioxide the water can absorb from the atmosphere, any changes in alkalinity can ultimately affect whether an estuary is a source or sink for carbon dioxide.

Ray Najjar, a biogeochemist from Pennsylvania State University, is the project lead, with collaborators specializing in ecology, organismal biology, chemistry, and physics from Woods Hole Oceanographic Institution, the Virginia Institute of Marine Science, and the University of Maryland Center for Environmental Science Chesapeake Biological Laboratory.

This project is funded by the National Science Foundation.