AQUASHIFT- the impact of climate variability on aquatic ecosystems
Climate models predict future warming for Germany’s seas and inland waters, especially during the winters. Temperature affects the organisms living in water in many ways: the speed of their growth, the amount of food they eat, and in the case of plants, their photosynthetic ability depend on it. This is why the temperature in the water is an important factor in determining when and where an organism occurs. However, organisms are very different in their reactions to changes in water temperature. This means that it is possible that predator and prey species, which occur at the same time and the same place in the present climate, will not be able to meet in the future. What will be the consequences of that? Will marine food chains be disrupted, with dire consequences for the ecosystems and the fisheries depending on them? Will new predator-prey relationships occur instead of the old ones?
Understanding these and similar questions was the goal of researchers working in the AQUASHIFT program. They studied the effects of warming on different species and whole ecosystems in both marine and well as freshwater systems. To get the whole picture about these complex questions, they used diverse methods- experiments, data analysis and modeling.
The studies in the program reported several instances when increasing water temperature had an effect on the organisms studied: some migrated northwards, some increased their metabolic rates and others occurred earlier than usual in spring. It also became clear during the program that the response of organisms and ecosystems to temperature increase is context-dependent: for example, the amount of nutrients and underwater light (influenced by cloudiness) have an influence on it. Besides of these (so-called abiotic) factors, an organism’s biotic interactions also modified the effects of temperature on it. Disruption of trophic chains was rarely observed during the experiments. Instead, the researchers observed complex responses of the communities depending on the number of interacting species and their relative sensitivities to temperature.
Prof. Dr. Ulrich Sommer
GEOMAR | Helmholtz Centre for Ocean Research Kiel
Düsternbrooker Weg 20
Phone: +49-431 600-4400
Fax: +49-431 600-4402
Phone: +49-43- 600-4401
Dr. Barbara Bauer