Presentation Abstract
Carbon storage in marine vegetated habitats (blue carbon) is increasingly being considered in carbon financing and coastal ecosystem management. Amongst other ecosystem functions, seagrass meadows are reported to be highly efficient at sequestering and storing significant amounts of carbon. However, seagrass blue carbon data remain sparse and regionally biased to tropical regions. In the Pacific Northwest, we lack information on the magnitude and variability of carbon stocks, as well as local drivers of variability. We collected sediment cores from six eelgrass meadows on the central coast of British Columbia, Canada, to quantify sedimentary organic carbon (Corg) stocks and accumulation rates. Carbon stocks exhibited 10-fold variability (335.35 – 3664. 48 g Corg m-2) in the top 20cm of sediment; these values align with other temperate eelgrass meadows, but are lower than reported global seagrass values. On average, Corg stocks within seagrass beds and adjacent unvegetated habitat overlapped, although stocks in the meadow interior (1392.05 g Corg m-2) were greater than those along meadow edges (1129.82 g Corg m-2) and in adjacent unvegetated sediments (977.10 g Corg m-2). Corg accumulation rates ranged from 12.57 to 50.45 g Corg m-2 year-1, lower than the global average reported for seagrasses (138 g Corg m-2 year-1), but again similar to other eelgrass meadows. Further, Corg in sediments beneath eelgrass meadows appears to be largely from non-eelgrass sources (terrestrial, benthic microalgae and macroalgae). Generalized linear mixed effects models suggest that hydrodynamic regime is the strongest driver of carbon stocks in the top 5cm of sediment, more important than the structural complexity of seagrass beds, or the proportion of fine sediments. Lower water velocities may allow greater deposition of particles within meadows, together with reduced erosion and resuspension. These results support physical characteristics over seagrass features as primary determinants of blue carbon storage in nearshore soft sediment habitats.
Session Title
Seagrass Cross-Border Connections: Management
Keywords
Eelgrass, Blue carbon
Conference Track
SSE4: Ecosystem Management, Policy, and Protection
Conference Name
Salish Sea Ecosystem Conference (2018 : Seattle, Wash.)
Document Type
Event
SSEC Identifier
SSE4-38
Start Date
5-4-2018 4:15 PM
End Date
5-4-2018 4:30 PM
Type of Presentation
Oral
Genre/Form
conference proceedings; presentations (communicative events)
Contributing Repository
Digital content made available by University Archives, Heritage Resources, Western Libraries, Western Washington University.
Subjects – Topical (LCSH)
Eelgrass--Carbon content--British Columbia
Geographic Coverage
British Columbia
Rights
This resource is displayed for educational purposes only and may be subject to U.S. and international copyright laws. For more information about rights or obtaining copies of this resource, please contact University Archives, Heritage Resources, Western Libraries, Western Washington University, Bellingham, WA 98225-9103, USA (360-650-7534; heritage.resources@wwu.edu) and refer to the collection name and identifier. Any materials cited must be attributed to the Salish Sea Ecosystem Conference Records, University Archives, Heritage Resources, Western Libraries, Western Washington University.
Type
Text
Language
English
Format
application/pdf
Included in
Fresh Water Studies Commons, Marine Biology Commons, Natural Resources and Conservation Commons, Terrestrial and Aquatic Ecology Commons
Hydrodynamic regime determines the magnitude of surface sediment 'blue carbon' stocks in British Columbia eelgrass meadows
Carbon storage in marine vegetated habitats (blue carbon) is increasingly being considered in carbon financing and coastal ecosystem management. Amongst other ecosystem functions, seagrass meadows are reported to be highly efficient at sequestering and storing significant amounts of carbon. However, seagrass blue carbon data remain sparse and regionally biased to tropical regions. In the Pacific Northwest, we lack information on the magnitude and variability of carbon stocks, as well as local drivers of variability. We collected sediment cores from six eelgrass meadows on the central coast of British Columbia, Canada, to quantify sedimentary organic carbon (Corg) stocks and accumulation rates. Carbon stocks exhibited 10-fold variability (335.35 – 3664. 48 g Corg m-2) in the top 20cm of sediment; these values align with other temperate eelgrass meadows, but are lower than reported global seagrass values. On average, Corg stocks within seagrass beds and adjacent unvegetated habitat overlapped, although stocks in the meadow interior (1392.05 g Corg m-2) were greater than those along meadow edges (1129.82 g Corg m-2) and in adjacent unvegetated sediments (977.10 g Corg m-2). Corg accumulation rates ranged from 12.57 to 50.45 g Corg m-2 year-1, lower than the global average reported for seagrasses (138 g Corg m-2 year-1), but again similar to other eelgrass meadows. Further, Corg in sediments beneath eelgrass meadows appears to be largely from non-eelgrass sources (terrestrial, benthic microalgae and macroalgae). Generalized linear mixed effects models suggest that hydrodynamic regime is the strongest driver of carbon stocks in the top 5cm of sediment, more important than the structural complexity of seagrass beds, or the proportion of fine sediments. Lower water velocities may allow greater deposition of particles within meadows, together with reduced erosion and resuspension. These results support physical characteristics over seagrass features as primary determinants of blue carbon storage in nearshore soft sediment habitats.
