Multiple Stressor Research
Multiple stressors: From the individual specimens to community responses in the field
We're living in a world where typically multiple stressors act on biota simultaneously. Classical ecotoxicological assays typically assess stressor-response relationships of individual species in response to individual stressors such as individual chemical compounds (e.g. pesticides). From the resulting data, threshold levels are derived, which also inform regulatory decisions. A main scientific challenge of our time is that the response of individual species on stressors depends on confounding additional abiotic and biotic factors/stressors.
Typically, one stressor alone induces a characteristic response for that organism (e.g. escape, physiological responses). However, if the organism is exposed to a second stressor at the same time (e.g. increased temperature) this second stressor can modulate the response of the first stressor. Therefore, the combined response of two stressors can increase the response (synergistic) or lower the response (antagonistic) in comparison to the anticipated additive effects.
Scheme of stressor responses
Additive: 1+1=2 (stressors multiplicate)
Synergistic: 1+1=3 (stressors enhance each other)
Antagonistic: 1+1=1 (stressors inhibit each other)
In addition to that, biotic interactions among species in a habitat can further modulate stressor responses, making the inference and prediction of distinct response difficult.
Together with national and international cooperation partners our group uses innovative outdoor experiments (ExStream experiments in particular) to investigate the effect of multiple stressors on species, communities, and ecosystem functionality.
Beermann, Arne J., Elbrecht, V., Karnatz, S., Ma, L., Matthaei, C.D., Piggott, J.J., Leese, F., 2018a. Multiple-stressor effects on stream macroinvertebrate communities: A mesocosm experiment manipulating salinity, fine sediment and flow velocity. Science of The Total Environment 610–611, 961–971. https://doi.org/10.1016/j.scitotenv.2017.08.084
Beermann, A. J., Elbrecht, V., Karnatz, S., Ma, L., Matthaei, C.D., Piggott, J.J., Leese, F., 2018. Multiple-stressor effects on stream macroinvertebrate communities: A mesocosm experiment manipulating salinity, fine sediment and flow velocity. Science of The Total Environment 610, 961–971.
Beermann, A.J., Werner, M.-T., Elbrecht, V., Zizka, V.M.A., Leese, F., 2021. DNA metabarcoding improves the detection of multiple stressor responses of stream invertebrates to increased salinity, fine sediment deposition and reduced flow velocity. Science of The Total Environment 750, 141969. https://doi.org/10.1016/j.scitotenv.2020.141969
Beermann, Arne J., Zizka, V.M.A., Elbrecht, V., Baranov, V., Leese, F., 2018b. DNA metabarcoding reveals the complex and hidden responses of chironomids to multiple stressors. Environmental Sciences Europe 30, 26. https://doi.org/10.1186/s12302-018-0157-x
Elbrecht, V., Beermann, A.J., Goessler, G., Neumann, J., Tollrian, R., Wagner, R., Wlecklik, A., Piggott, J.J., Matthaei, C.D., Leese, F., 2016. Multiple‐stressor effects on stream invertebrates: a mesocosm experiment manipulating nutrients, fine sediment and flow velocity. Freshwater Biology 61, 362–375.