Exploring tipping points in the Arctic Ocean
Sea ice loss, rising temperatures, invasive species: the Arctic marine world is undergoing a lot of change. Predicting the future of marine biodiversity is key, both for the ecosystems themselves and for the local societies that rely on them for their livelihoods. This is challenging due to huge gaps in our knowledge, the largest of which is a lack of understanding of the biological processes that link biodiversity to ecosystem services, and how they react to pressures from human activity. “If we don’t know how the pelagic (open ocean) food webs in the Arctic function or respond to changes, we cannot predict how the fisheries productivity will change, or how much CO2 might be taken up and sequestered in the future ocean through biological processes,” explains Marja Koski, a professor at the Technical University of Denmark’s National Institute of Aquatic Resources and ECOTIP project coordinator. In the ECOTIP project, researchers are shedding light on Arctic marine ecosystems. This includes exploring the drivers and thresholds of ecosystem tipping cascades, where a fundamental shift in the environment moves an ecosystem into a different state, as well as their consequences for Arctic marine biodiversity.
Past and present
The researchers gathered data during expeditions around the coasts of Greenland, combining this with existing time-series data to support advanced modelling. They combined these with historical records, as well as prehistorical sediment data, and developed models to identify the mechanisms and consequences of environmental change – for instance, how subtle changes in the environment can result in ecosystem tipping points. While the project is still ongoing, the team has mapped a lot of past and present biodiversity and its response to external pressures, and developed a new understanding of pelagic food webs and links between the seabed and water column of Arctic ecosystems. “Our modelling results have identified a mechanism for potential ecosystem tipping points, which needs to be verified and refined by the observations which we are currently working on,” says Koski. The researchers have also explored the distribution changes of fish and marine mammals and how this affects the local communities. For instance, an examination of fishing logbook records showed that new fish and whale species spread to East Greenland from the south, whereas the ice-associated mammals (such as walrus and narwhal) withdrew to the north. The results have also improved our understanding of the biological carbon pump – a combination of biological processes that help to draw carbon out of the atmosphere – revealing that particularly large zooplankton and fish are globally important agents of carbon export and sequestration.
Integrating local knowledge
Engagement with Greenlandic society was an important part of the project, and the local ecological knowledge contributed greatly to the outcome. The team are now finalising the data and creating policy recommendations to assist with future management and monitoring. The work will also continue in the EU-funded SEA-Quester project, exploring the carbon sequestration potential of novel polar ecosystems. “We hope that we can build on the insights and data, and continue the collaborations that have been built during ECOTIP,” concludes Koski.
Keywords
ECOTIP, Arctic, historical, observations, ecosystem services, carbon pump, CO2