Functional ecology of interactome-predicted key ciliates in deep temperate lakes

• Applicant: Professor Dr. Thorsten Stoeck
• Subject Area: Ecology and Biodiversity of Animals and Ecosystems, Organismic Interactions
• Term: since 2015
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 273766911

Revealing the extraordinarily complex relationships among the involved key players in aquatic food webs is a central topic in freshwater ecology. Such key players are species with important functions in the plankton community and which, when lost because of e.g. climate stressors, could cause the collapse of the interactome networks. Aquatic food webs consist of microscopic organisms, including bacteria and protists, and small metazoans that co-occur in seasonal cycles. The analyses of environmental DNA metabarcodes, obtained from plankton samples, and subsequent integration of these massive sequence datasets into interactome network analyses emerged as a very powerful tool to uncovered the entirety of interactions, biotic and abiotic, in these complex aquatic food webs. Among others, statistical analyses of network properties allow for the detection of key species. In such DNA-based networks obtained from two deep alpine lakes in previous project, especially ciliates emerged as a most important taxon group. Unfortunately, due to the incompleteness of nucleotide databases, the sequences of numerous ciliates which are key species in interactome networks cannot be taxonomically assigned beyond phylum level. This failure hampers further research and the exploitation of network results. For example, no cultures can be established to conduct autecological experiments to reveal the functional traits, lifestyle and ecological importance as proposed by the interactome structures. Also, in situ observations of the morphospecies in their natural environments to infer ecological information is not possible. Therefore, the goal of the proposed extension project is to investigate the functional role of previously unidentified key ciliates hiding in the plankton interactome of two deep temperate lakes (Lake Mondsee and Lake Zurich) using state-of-the-art molecular and microscopy techniques, cultivation techniques, lab-based experiments (microcosms) and also field observations. The expected results will help to better predict changes in lake ecosystem function, as well as the resilience and response of these lakes under stress (climatic and other stressors).

• DFG Programme: Research Grants