In this post, Matthias Liess from the Helmholtz Centre for Environmental Research (UFZ) reports on their recent paper “Predicting the synergy of multiple stress effects”.

Environmental stress increases toxicant sensitivity of various aquatic organisms. The magnitude of environmental stress is expressed as mortality without toxicant exposure. The increase in toxicant sensitivity is based on observations of aquatic vertebrate and invertebrate studies including 6 different environmental stressors, 5 toxicants and 10 species.

Toxicants and other, non-chemical environmental stressors contribute to the global biodiversity crisis. Examples include the loss of bees and the reduction of aquatic biodiversity. The widespread existence of these impacts suggests that the current approach of pesticide risk assessment fails to protect biodiversity when multiple stressors concurrently affect organisms. To quantify such multiple stress effects, we analysed all applicable aquatic studies and found that the presence of environmental stressors increases individual sensitivity to toxicants by a factor of up to 100. To predict this dependence, we developed the “Stress Addition Model” (SAM). With this approach, we provide a tool that quantitatively predicts the highly synergistic direct effects of independent stressor combinations. We provide an EXCEL spreadsheet to calculate own data.

If you want to know how SAM is working, then read the paper in SCIENTIFIC REPORTS, authored by Matthias Liess, Kaarina Foit, and Saskia Knillmann, who are with the Department of System-Ecotoxicology at the UFZ, as well as  Ralf B. Schäfer and Hans-Dieter Liess.

For further information or a collaboration on this subject contact Matthias Liess.