Expanding Greenland seagrass meadows contribute new sediment carbon sinks

Núria Marbà,Carlos M Duarte,Pere Masqué,Dorte Krause-Jensen

doi:10.1038/s41598-018-32249-w

Abstract

The loss of natural carbon sinks, such as seagrass meadows, contributes to grenhouse gas emissions and, thus, global warming. Whereas seagrass meadows are declining in temperate and tropical regions, they are expected to expand into the Arctic with future warming. Using paleoreconstruction of carbon burial and sources of organic carbon to shallow coastal sediments of three Greenland seagrass (Zostera marina) meadows of contrasting density and age, we test the hypothesis that Arctic seagrass meadows are expanding along with the associated sediment carbon sinks. We show that sediments accreted before 1900 were highly 13C depleted, indicative of low inputs of seagrass carbon, whereas from 1940’s to present carbon burial rates increased greatly and sediment carbon stocks were largely enriched with seagrass material. Currently, the increase of seagrass carbon inputs to sediments of lush and dense meadows (Kapisillit and Ameralik) was 2.6 fold larger than that of sparse meadows with low biomass (Kobbefjord). Our results demonstrate an increasing important role of Arctic seagrass meadows in supporting sediment carbon sinks, likely to be enhanced with future Arctic warming.

Highlights

The loss of natural carbon sinks, such as seagrass meadows, contributes to grenhouse gas emissions and, global warming
This trend has led to the hypothesis that marine macrophytes, including kelps and seagrass, would likely expand into the Arctic with future warming and reduced ice cover[9]
Whereas kelps already extend to very high latitudes (e.g. 80°N in Svalbard)[10], the northern limit of eelgrass (Zostera marina), the seagrass species growing at highest latitudes in the Arctic[11], is set around 70°N in areas influenced by warm Atlantic waters[12] and further south, around 64°N in

Summary

Introduction

The loss of natural carbon sinks, such as seagrass meadows, contributes to grenhouse gas emissions and, global warming. We reconstruct the contribution of eelgrass to organic carbon burial in sediments under three contrasting eelgrass meadows in Western Greenland.

Results

Conclusion