Estimating Carbon Storage in Eelgrass Meadows in the Gulf of Maine

Seagrass meadows can be hotspots for carbon storage and sequestration, but the data currently available shows an enormous amount of variability. Carbon storage varies with seagrass species and region, and with meadow condition, where healthy meadows sequester carbon but those that are declining may be sources of inorganic carbon to the atmosphere. Very little is known about carbon storage in Zostera marina (eelgrass) meadows in the Gulf of Maine, where they are threatened by poor water quality and physical disturbance. In 2014 we studied two eelgrass meadows in coastal Massachusetts, U.S.A. We sampled biomass and measured carbon content in above- and below-ground plant tissues, sediments, and particulate organic matter in the water column. We estimated bed density and extent using a combination of sonar, visual imaging, and diver surveys. To investigate persistence of carbon storage in sediments, we also sampled sediments from an area where a meadow had historically existed, but had died back in 2012. Results of this work will not only support eelgrass restoration and protection measures locally, but will also help clarify our global understanding of carbon storage in blue habitats.