Collaborative Studies of Two Resource Ecosystems in Shelf, Slope and Oceanic Regions of the Norwegian and South-China Seas

The waters off Lofoten, Vesterålen and Troms and the heavily populated Guandong region, with several big cities, are characterized as high-productive marine areas on the shelf and continental slopes that lead down to the deep sea. Both areas have traditional fisheries with great importance for the local population and the regions, and large local, regional and international maritime traffic. The South China Sea and the waters outside Northern Norway are affected by climate change and potential pollution and noise from maritime traffic, fisheries and harvesting on several trophic levels, petroleum activity, and in addition, shelf areas outside China are affected by pollution from the big cities. Meso-scale eddies outside Lofoten were described in the Carta Marina as early as 1693, and are well known by local fishermen. These eddie structures are typical of the marine systems both in the South China Sea and in the waters outside Northern Norway. Both areas have a typical bloom system of phytoplankton and an effective lipid-based (marine fat) transport of energy through the ecosystem via herbivorous zooplankton (Calanus and krill) to fish, mammals and seabirds. In this project we studied the physical conditions in the ocean and how the eddy formation affects the distribution of nutrients, the biological processes associated with phytoplankton dynamics, shoals and swarm formation of small crustaceans (structure of zooplankton) and the energy transfer in the ecosystem. We found that the Lofoten-Vesterålen marine ecosystem is particularly productive because of strong front that acts as a transport barrier and allows cod larvae to grow in a spatio-temporal match with their favourite prey. At the same time, we also found that mesoscale eddies in the Norwegian Sea collect Calanus copepods when they overvinter at great depth, and transport the copepods back to the shelf, where they ascend in spring and produce the nauplii, which are the principal prey of cod larvae. All of these processes are related to natural and anthropogenic stressors. Due to the pandemic we could not investigate the system in the northern South China Sea, but results from the Norwegian Sea were possible because we could use both a research vessel with the most modern equipment and autonomous platforms (gliders) equipped with newly developed echosounders to stud eddy formation and zooplankton and fish larvae in the upper water layers. In addition we used a Seaglider that descended from the surface to 1000 m with instruments to study ocean current, temperature and salinity of the eddies. We also significantly advanced on the approach to quantify zooplankton based on ocean colour remote sensing.

The scientific outlet was through 12 open-access articles in peer reviewed scientific journals, along with presentations at international science conferences. Results from Stressor were incorporated into lectures in courses at UiT and SJTU. Results were communicated to fishing companies for improving fishing technologies and efficiency and were also communicated to the Norwegian Directorate of Fisheries to aid in an awareness of mesoscale patterns to prepare against oil spills and to protect fish stocks. Outlet to the wider public was somewhat limited due to the pandemic, so were mostly conveyed through popular science publications.

Marine ecosystems around the world are under threat from a growing number of anthropogenic stressors with large predicted effects on coastal communities. Our Sino-Norway collaborative research proposal STRESSOR directly addresses this issue as outlined in the research area “Integrated multi-stressor impacts on ecosystems” by the joint call. STRESSOR will seek new understandings on responses of shelf-slope-oceanic ecosystems in two pressured slope regions, the northern Norwegian Sea and the northern South China Sea, to anthropogenic impacts and climate change. Both slope regions are biological hot spots with large aggregations of plankton and fish species, and both systems feature permanent shelf slope currents and meso- and submeso-scale eddies that are responsible for the shelf-ocean transport of nutrients, contaminants and populations of key species. The two systems are stressed to a varying degree by heavy fisheries, oil field development, and/or contaminants from megacities and industries. STRESSOR will examine quantitative and qualitative impacts of anthropogenic and natural stressors on the ecosystems by addressing biophysical interactions in the shelf-ocean ecosystems. We will take a holistic systematic approach to study the similarities and differences between Chinese and Norwegian shelf-slope-oceanic ecosystems by developing novel interdisciplinary sensor packages and fieldwork strategies, and by establishing a collaborative Chinese and Norwegian research team. One of our novel technical features is to integrate already developed multiple physical-biogeochemical sensor systems, traditional ship and contemporary automated surface and underwater vehicle based observations, satellite remote sensing and modeling for developing a systematic statistically based approach for mapping and long term monitoring of key stressors so that we can monitor ecosystem and resource changes and delineate anthropogenic and climate change impacts.