Publication Date:
2016-04-27
Description:
Although seagrasses cover only a minor fraction of the ocean seafloor, their carbon sink capacity account for nearly one-fifth of the oceanic carbon burial and thus play a critical structural and functional role in many coastal ecosystems. We sampled 10 eelgrass (Zostera marina) meadows in Finland and 10 in Denmark to explore the seagrass carbon stocks (Corg stock) and the carbon accumulation (Corg accumulation) in the Baltic Sea area. The study sites represent a gradient from sheltered to exposed locations in both regions to reflect expected minimum and maximum stocks and accumulation. The Corg stock integrated over the top 25 cm of the sediment averaged 627g C m−2 in Finland, while in Denmark the average Corg stock was over six times higher (4324 g C m−2). A conservative estimate of the total carbon pool in the regions ranged between 8.6–46.2 t ha−1. Our results suggest that the Finnish eelgrass meadows are minor carbon sinks compared to the Danish meadows, and that majority of the Corg produced in the Finnish meadows is exported. Similarly, the estimates for Corg accumulation in eelgrass meadows in Finland (〈 0.002–0.033 t C y−1) were over two orders of magnitude lower compared to Denmark (0.376–3.636 Corg t y−1). Our analysis further showed that 〉 40 % of the variation in the Corg stocks was explained by sediment characteristics (density, porosity and silt content). In addition, the DistLm analysis showed, that root: shoot- ratio of Z. marina explained 〉 12 % and contribution of Z. marina detritus to the sediment surface Corg pool 〉 10 % of the variation in the Corg stocks, whereas annual eelgrass production explained additional 2.3 %. The mean monetary value for the present carbon storage and sequestration capacity of eelgrass meadows at Finland and Denmark, were 346 and 1862 € ha−1, respectively. We conclude that in order to produce reliable estimates on the magnitude of eelgrass Corg stocks, Corg accumulation and the monetary value of these services, more Blue Carbon studies investigating the role of sediment biogeochemistry, seascape structure, plant species architecture and hydrodynamic regime for seagrass carbon storage capacity are in urgent need.
Print ISSN:
1810-6277
Electronic ISSN:
1810-6285
Topics:
Biology
,
Geosciences
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