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Projekt Druckansicht

Mechanismen von Ressourcen-Co-Limitierung auf Planktongemeinschaftsebene

Antragsteller Professor Dr. Alexander Wacker, seit 4/2024
Fachliche Zuordnung Ökologie und Biodiversität der Tiere und Ökosysteme, Organismische Interaktionen
Ökologie und Biodiversität der Pflanzen und Ökosysteme
Förderung Förderung von 2020 bis 2024
Projektkennung Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 449402474
 
Erstellungsjahr 2025

Zusammenfassung der Projektergebnisse

The availability of limiting resources shapes the diversity of food webs and ecosystems. Across natural systems, organisms or communities are often co-limited, because their growth response is limited by more than one resource simultaneously. Nitrogen (N) and phosphorus (P) are the primary limiting resources for autotrophs, and both nutrients frequently co-limit the growth of primary producer communities. On the other hand, excessive N and P supplies to aquatic autotrophs can lead to eutrophication and proliferation of toxic phytoplankton species. In addition, not only the amount but also the relative supply (N:P ratio) of nutrients is important for the growth response of autotrophs. Depending on nutrient amount and ratios and thus limiting conditions, phytoplankton communities can show large variations in biomass, nutrient stoichiometry, species composition, and biochemical composition. These changes can lead to consequences for the growth of herbivores feeding on phytoplankton, impacting the trophic transfer efficiency in food webs. Despite being well-studied and understood in primary producers, there is lack of information on the observed mechanisms leading to co-limitation at the community level. Furthermore, there are knowledge gaps about how co-limitation translates across trophic levels from primary producers to consumers, the relative importance of nutritional and community traits, and how the response of herbivores changes in the presence of predators. The project aims to fill these gaps and provides novel data on N and P co-limitation in the community context across trophic levels through microcosm and mesocosm experiments. Our experiments showed that, among possible mechanisms, the dominance of species or groups with similar traits regarding nutrient requirements explains (co-)limitation patterns observed at the community level in phytoplankton. Across trophic levels, the response of distinct zooplankton species to N and P (co-)limited communities differs from that of their food (i.e. the phytoplankton). An interplay between food nutritional traits, in particular stoichiometry, and traits related to community composition play a major role in the herbivores’ response. When predators are introduced in the systems, the response to N and P additions changed in phytoplankton and zooplankton communities due to competition and nutrient remineralization. Finally, in a more natural setting, selective predation on herbivores can trigger trophic cascades and modify phytoplankton community composition and biomass patterns overcoming the effects of nutrient co-limitation. As nutrient manipulations and loading are currently altering global biogeochemical cycles, disrupting food chains, and triggering toxic algal blooms, our findings highlight the importance of understanding and predicting the response of organisms in aquatic communities to changes in nutrient availability.

Projektbezogene Publikationen (Auswahl)

 
 

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