The capability of some coastal vegetated ecosystems (seagrass meadows, mangrove forests, and tidal marshes) to sequester CO2 and store large organic carbon stocks is drawing increasing attention as a potential means of conservation-based climate change mitigation. Despite the fact that the Caribbean region supports large expanses of seagrass meadows, information on the status and trends and carbon density of Caribbean seagrass meadows is surprisingly sparse. Further, evidence of widespread declines of seagrasses across the region suggest that Caribbean seagrass blue carbon stocks are at risk to add to global warming. To address these uncertainties, the CariCAS project aims to 1) build a collaborative network of Caribbean seagrass scientists interested in blue carbon and to 2) outfit local experts from the new network to collect the data needed to construct inventories of seagrass blue carbon to a depth of 1m from as many seagrass sites across the Caribbean as possible to understand the range, variation, and environmental correlates of seagrass C stocks. These data will be combined with seagrass mapping to generate first-order estimates of the amount of C stored in seagrasses across the region.
This field guide complements online workshops for CariCAS project partners and describes the field and laboratory methods used to characterize blue carbon in seagrass meadows. At each project site, seagrass abundance will be assessed at 16 0.25 m2 quadrats placed at random locations within the site. Eight 15 cm diameter cores will be taken to assess seagrass biomass and to provide the material for seagrass biomass carbon and nutrient content. All seagrasses within each of the three cores will be separated by species and tissue type, washed and scraped to remove epiphytes, then dried and weighed. Following the collection of seagrass biomass cores, a piston core will be taken of uncompressed soils, making an attempt to drive the core 1 m into the sediment or until refusal. Cores will be subsampled at 5 cm depth intervals using small subcores. All subcores will be weighed wet to permit the calculation of porosity and soil dry bulk density. Seagrass tissue and sediment samples will be oven-dried at 60°C, and dry weight recorded. Finally, samples will be shipped to FIU’s Blue Carbon Analysis Laboratory for determination of Loss on Ignition, total carbon content, inorganic carbon content, organic carbon content, and carbon and nitrogen stable isotope ratios. The resulting data will be used to estimate seagrass carbon stocks and their relationship with covariates, as well as being integrated with seagrass mapping efforts led by The Nature Conservancy to quantify seagrass carbon stocks of the Caribbean region.
For more information about this project, please contact Dr. Jim Fourqurean at
fourqure@fiu.edu.