Understanding the processes shaping the structures and functioning of ecosystem is key to assess their vulnerability and predict their development under stress. The trait-driver theory (TDT) was recently introduced to describe the relationship between organisms’ characteristics (traits), their assembling in communities and the emerging ecological functions. In so, it mechanistically details the processes underpinning response capacity (RC), the efficiency of a system in maintaining functionality by changing structures when conditions change. Despite being a fundamental concept in resilience theory, no direct measurements of RC has been drawn from empirical observations, so far. Furthermore, a detailed experimental assessment of TDT predictions is missing too. We ran <i>in situ</i> experiments with two distinct lake phytoplankton communities stressed for the first time with a mixture of micropollutants at environmentally realistic concentrations. We drew TDT expectations on community responses using an individual-base model, compared formally elaborated theoretical expectations with the results of the experiment, and found that TDT successfully predicts changes in size distribution, functional group turn-over and functional responses of the two communities. We also provide empirical evidence and a measure of their RC by looking at the rate of change of phytoplankton traits and its correlation with production. An empirical assessment of ecosystem RC is presented here for the first time. RC emerges as a trait-based measure of community responses linked to the maintenance of ecological functions under environmental changes.

Trait driver ecological theory predicts complex responses of phytoplankton exposed to chemical stress

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.