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On Thursday 1 October 2020, Gea van der Lee will defend her PhD thesis

Detail Summary
Date 1 October 2020
Time 16:00

Oudezijds Voorburgwal 229 - 231
1012 EZ Amsterdam

Organisms make ecosystems function: Identifying functional indicators of anthropogenic stress in aquatic ecosystems

To gain insight into how aquatic ecosystems change under anthropogenic stress, we need suitable indicators. Traditionally, most biomonitoring schemes have relied on structural indicators based on single point-in-time taxonomic inventories of species groups that comprise the ecosystem, assuming these are representative of the functioning of an ecosystem. However, anthropogenic stress may impact ecosystem structure and functioning differently. It has thus been argued that direct measurements of ecosystem functioning are necessary. The aim of this thesis was, therefore, to identify functional indicators of anthropogenic stress in aquatic ecosystems using ecosystem processes and functional roles of organisms, and to explore their potential use in biomonitoring schemes. To this purpose multiple field studies were conducted in linear shaped small and shallow lowland water bodies. It was shown that 1) detailed quantification of environmental processes, such as  discharge dynamics and dissolved oxygen dynamics, is necessary to comprehend the temporal patterns in abiotic features leading to biotic changes, 2) these environmental processes are an important factor in setting the context in which organisms fulfill their functional roles in resource use, and therewith regulate ecological processes, 3) the impact of anthropogenic stressors on ecological processes, such as decomposition and ecosystem metabolism, is often complex, as there is usually a combination of multiple stressors involved. I recommended that future research on ecosystem functioning should focus on the potential trophic and non-trophic functional roles fulfilled by organisms within different contexts changing over time, as ultimately orga