Macroalgal forests export much of their production, partly supporting food webs and carbon stocks beyond their habitat, but evidence of their contribution in sediment carbon stocks is poor. We test the hypothesis that macroalgae contribute to carbon stocks in arctic marine sediments. We used environmental DNA (eDNA) fingerprinting on a large-scale set of surface sediment samples from Greenland and Svalbard. We evaluated eDNA results by comparing with traditional survey and tracer methods. The eDNA-based survey identified macroalgae in 94 % of the sediment samples covering shallow nearshore areas to 1460 m depth and 350 km offshore, with highest sequence abundance nearshore and with dominance of brown macroalgae. Overall, the eDNA results reflected the potential source communities of macroalgae and eelgrass assessed by traditional surveys, with the most abundant orders being common among different methods. A stable isotope analysis showed a considerable contribution from macroalgae in sediments although with high uncertainty, highlighting eDNA as a great improvement and supplement for documenting macroalgae as a contributor to sediment carbon stocks. Conclusively, we provide evidence for a prevalent contribution of macroalgal forests in arctic surface sediments, nearshore as well as offshore, identifying brown algae as main contributors.
Bibliographical noteFunding Information:
This research was supported by the Independent Research Fund Denmark ( 8021-00222 B , ‘CARMA’) and the Greenland Monitoring Program to DK-J, and King Abdullah University of Science and Technology through baseline funding provided to CMD. We are thankful to Fréderic Olivier, Laurant Chauvaud, Silvian Chauvaud, Erwan Amice, Mie Winding, Ole Gertz, Tage Dalsgaard, Camilla Andresen and Egon Frandsen for assistance in sampling surface sediments, and we thank Ruben Diaz-Rua, Wajitha Sait and Kitte Gerlich for assistance in the laboratory. We are also thankful to Thomas Larsen for providing advice on the Bayesian mixing model analysis. Finally, we thank the Arctic research station in Qeqertarsuup tunua, Greenland, and the multiple scientific cruises that provided a platform for our widespread sampling in both Greenland and Svalbard.
© 2023 The Authors
- Blue carbon
- Carbon stocks
- Environmental DNA
- Stable isotopes
ASJC Scopus subject areas
- Environmental Engineering
- Environmental Chemistry
- Waste Management and Disposal