Trophic interactions are key to understanding food web processes and ecosystem functioning. Nutrients are transferred from primary producers to higher trophic levels, while at the same time, predation is one of the main drivers for natural selection. In response to predation, many aquatic prey species have evolved defences that reduce the predation impact. However, defence against one predator could render the prey more vulnerable to other predators. Hence, phenotypic plasticity in defensive traits in prey is a widespread mechanism to cope with a frequently changing predator spectrum. This plasticity may imply changing demands in resources, e.g., for changes in morphology or life history (e.g., number and size of offspring). Therefore, the composition of the phytoplankton community, and thereby the nutrient availability for grazers, may lead to nutrient limitations that potentially also constrain the expression of defences. To get a more comprehensive understanding of how prey suffers from insufficient nutrient supply, we will study the impact of nutrient availability on the expression of defences in cladocerans of the genus Daphnia. Daphnia are unselective filter-feeders, which play a crucial role in the nutrient transfer from primary producers to higher trophic levels in lentic freshwater ecosystems and provide a well-established model system in research on predator-prey interactions and nutritional ecology. However, under climate change, Daphnia will be subjected to increased nutrient limitations, e.g., by cyanobacterial blooms.

In this project, combining adaptive plasticity and trophic interactions under nutritional constraints, we will explore the impact of food quantity and quality on the expression of inducible defences using established predator-prey systems. It is in cooperation with the working group of C. Laforsch from the University of Bayreuth and D. Martin-Creuzburg from the Research station for Aquatic Ecology in Bad Saarow of the University of Technology, Cottbus-Senftenberg. We will evaluate how defence expression and resource allocation in Daphnia is influenced by the availability of carbon and important nutrients, like essential lipids, and how the different defensive traits are affected by supplying single nutrients and different combinations of nutrients. Furthermore, we will assess the demand of Daphnia for total carbon as well as other nutrients during simulated predator exposure. By exploring these changes and assessing nutritional costs for inducible defences, we will be able to gain an improved mechanistic understanding of how inducible defences in Daphnia are affected by the phytoplankton community and how nutrient limitations may constrain the expression of defences and how this affects ecosystem stability. This will contribute to our understanding of trophic interactions, population dynamics and food web processes.

Shatto, C., Kiene, M., Hofmann, P., Walentowitz, A., Wilkens, V., Heuser, T., & Weiser, F. (2024). Assessing the recovery of Pinus canariensis stands after wildfires and volcanic eruption on La Palma, Canary Islands. Forest Ecology and Management, 572, 122317. doi.org/10.1016/j.foreco.2024.122317

Wild, A. J., Steiner, F. A., Kiene, M., Tyborski, N., Tung, S. Y., Koehler, T., ... & Pausch, J. (2024). Unraveling root and rhizosphere traits in temperate maize landraces and modern cultivars: Implications for soil resource acquisition and drought adaptation. Plant, Cell & Environment. doi.org/10.1111/pce.14898

Kiene, M., Schott, M., Martin‐Creuzburg, D., & Laforsch, C. (2024). Food quantity and quality modulates inducible defenses in a common predator–prey system. Limnology and Oceanography, 69(7), 1535-1546. doi.org/10.1002/lno.12595

Diel, P., Kiene, M., & Laforsch, C. (2024). Variation in defensive spines across juvenile instars of Daphnia magna. Journal of Plankton Research, 46(4), 452-458. doi.org/10.1093/plankt/fbae033

Kiene, M.; Wacker, A.; Martin-Creuzburg, D. (2023). Omega-3 versus Omega-6: Are We Underestimating the Ecological Significance of Arachidonic Acid in Aquatic Systems? Biomolecules, 13, 791. doi.org/10.3390/biom13050791

Diel, P. & Kiene, M.; Martin-Creuzburg, D.; Laforsch, C. (2020). Knowing the Enemy: Inducible Defences in Freshwater Zooplankton. Diversity, 12, 147. doi.org/10.3390/d12040147

Cladocera XII 2024 – Presentation: Food quantity and quality modulate inducible defences in a
common predator-prey system.

Jahrestagung der Deutschen Gesellschaft für Limnologie 2023 – Presentation: Defence evaluation of distinct morphological trait changes.

Conference of the International Society of Limnology 2022 – Presentation: The Defence Index: A framework to simplify studies on complex defence strategies.

Cladocera XII 2024 – 2. Place: „Outstanding student presentation“