Eelgrass (Zostera marina) meadows provide many ecosystem goods and services but high rates of carbon sequestration may not be one of them
Presentation Abstract
Coastal wetlands are known to be efficient carbon sinks due to carbon burial by mineral sediments, high rates of primary productivity, and low rates of decomposition. Of the three coastal wetland types: tidal marshes, tidal forests, and seagrass meadows, carbon burial by seagrasses is relatively under-studied, with reported rates ranging widely from 45 to 190 g C m-2 yr-1. Additionally, most of these seagrass data are from the species Posidonia oceanica and not from Zostera marina, the species common to the Pacific Northwest. In this study, we measured sediment organic matter and long-term accretion rates to estimate carbon stocks and sequestration rates for a Z. marina meadow in Padilla Bay, a U.S. National Estuarine Research Reserve in the Salish Sea. We found rates of carbon sequestration to be quite low, averaging 20 g C m-2 yr-1, due to both low sediment organic content and low rates of accretion. We postulate here that Padilla Bay’s low carbon sequestration capacity may be representative of most Z. marina meadows rather than an outlier, and that Z. marina meadows have an inherently low carbon sequestration capacity due to the species’ low tolerance for suspended sediment (which limits light availability) and sediment organic content (which leads to toxic sulfide levels). We note here that we are reporting only on the rates of carbon sequestration and not the standing stock, which can still be quite high despite low rates of sequestration. As a next step, research should focus on measuring carbon sequestration rates from other Z. marina meadows, particularly from sites that exhibit, a-priory, a potential for higher rates of carbon sequestration (i.e., existing beds in active depositional zones, if such a thing exists).
Session Title
The Role of Eelgrass Ecosystems in the Salish Sea
Conference Track
Habitat
Conference Name
Salish Sea Ecosystem Conference (2016 : Vancouver, B.C.)
Document Type
Event
Start Date
2016 12:00 AM
End Date
2016 12:00 AM
Location
2016SSEC
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--Effect of sediments on--Washington (State)--Padilla Bay; Carbon sequestration--Washington (State)--Padilla Bay
Geographic Coverage
Padilla Bay (Wash.); Salish Sea (B.C. and Wash.)
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
Eelgrass (Zostera marina) meadows provide many ecosystem goods and services but high rates of carbon sequestration may not be one of them
2016SSEC
Coastal wetlands are known to be efficient carbon sinks due to carbon burial by mineral sediments, high rates of primary productivity, and low rates of decomposition. Of the three coastal wetland types: tidal marshes, tidal forests, and seagrass meadows, carbon burial by seagrasses is relatively under-studied, with reported rates ranging widely from 45 to 190 g C m-2 yr-1. Additionally, most of these seagrass data are from the species Posidonia oceanica and not from Zostera marina, the species common to the Pacific Northwest. In this study, we measured sediment organic matter and long-term accretion rates to estimate carbon stocks and sequestration rates for a Z. marina meadow in Padilla Bay, a U.S. National Estuarine Research Reserve in the Salish Sea. We found rates of carbon sequestration to be quite low, averaging 20 g C m-2 yr-1, due to both low sediment organic content and low rates of accretion. We postulate here that Padilla Bay’s low carbon sequestration capacity may be representative of most Z. marina meadows rather than an outlier, and that Z. marina meadows have an inherently low carbon sequestration capacity due to the species’ low tolerance for suspended sediment (which limits light availability) and sediment organic content (which leads to toxic sulfide levels). We note here that we are reporting only on the rates of carbon sequestration and not the standing stock, which can still be quite high despite low rates of sequestration. As a next step, research should focus on measuring carbon sequestration rates from other Z. marina meadows, particularly from sites that exhibit, a-priory, a potential for higher rates of carbon sequestration (i.e., existing beds in active depositional zones, if such a thing exists).
