Seabirds can transfer significant amounts of marine nutrients to terrestrial ecosystems and thereby species communities adjacent to breeding colonies. This marine-terrestrial ecosystem coupling can operate through a range of different pathways e.g., seabirds derived nutrients have been shown to result in complex changes in spider and insect communities and general productivity increase terrestrial plants.

This project focus on runoff from the largest seabird colony that create favorable conditions for Chironomidae (Diptera), which in turn are important in the diet of terrestrial insectivorous birds. The study will investigate this around the largest seabird colony in the Baltic Sea, the island of Stora Karlsö.

Factors explaining high Chironomidae abundance in the Baltic Sea are not well known but appears to correlate with high nutrients and low oxygen levels. Thus, a combination of seabird-driven nutrient enrichment and the current oxygen depletion in the area between Öland and Gotland may have created optimal conditions for Chironomidae, with possible positive effects on terrestrial insectivorous bird populations.  

This project will study the hydrographical and geochemical conditions and abundance of Chironomidae larvae through vessel-based sampling at 15 stations in a transect from the seabird colony towards deeper waters west of the colony.

This project includes analysing previously collected data from the Baltic Sea soft sediment monitoring program to investigate in detail what hydrographical and geochemical conditions favor high Chironomidae abundances. That data will be compared to the obtained results obtained from this specific sampling program.

Researchers and departments:
Jonas Hentati-Sundberg, Stockholm Resilience Centre & SLU-Aqua
Henrik Österblom, Stockholm Resilience Centre
Caroline Raymond, Department of Ecology, Environment and Plant Sciences (DEEP)
Ola Svensson, DEEP
Jonas Gunnarsson, DEEP
Stefano Bonaglia, Department of Geology, Lund University