A new research initiative at Tvärminne Zoological Station (TZS) brings together long-term research projects and conducts field and laboratory experiments, all in order to understand the function of the Baltic food web and how it is affected by environmental change. The research focuses on a community module consisting of blue mussels, eider ducks and white tailed sea eagles. This module forms a central part of the Baltic ecosystem and contains a keystone species, a mesopredator and a top predator and it links the marine and the terrestrial environments. We investigate the direct and trophically mediated impacts of environmental change within this group of closely interacting species representing three different trophic levels. Special emphasis is put on the trophic interactions surrounding the eider duck and how these affect its population development. The eider populations are in precipitous decline and the species was recently classified as endangered within the EU. We hope to understand what processes are driving the eider populations and to mitigate potential threats.
In 2017 Kim Jaatinen (TZS) and Markus Öst (Åbo Akademi) conducted their traditional fieldwork studying the Tvärminne eider population. This season was especially interesting and worrisome: the research group recorded an all time low in the population’s offspring production. Normally the 12 km wide research area produces between 1000 and 2000 ducklings, but this year only a mere 41 ducklings were seen in the standard duckling survey conducted at the end of June. Predation by sea eagles plays a major role in this low production but also other causes are under investigation.
The blue mussel study conducted by Mats Westerbom, Kim Jaatinen and Alf Norkko focuses this year on analysing the effects of climate change on the population dynamics of this species so central to the Baltic ecosystem. In addition to applying new analysis techniques to the long-term data, the group has continued work on monitoring recruitment of young mussels to the population. This year a new monitoring scheme was started, which aims at following spatial and temporal variations in the condition (i.e., meat content) of the mussels.
The findings of this year’s projects will all shed light on the impact we are having on the Baltic Sea and how its ecosystem will be affected. This knowledge may help us mitigate the bad influence we are having on our environment. Stay tuned for upcoming results!
Text: Dr. Kim Jaatinen, Tvärminne Zoological Station
Photos: Heikki Eriksson & Kim Jaatinen