Predicting the synergy of multiple stress effects.
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. Although non-compliance with regulations might be contributing, the widespread existence of these impacts suggests that for example 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 (pesticides, trace metals) by a factor of up to 100. To predict this dependence, we developed the "Stress Addition Model" (SAM). With the SAM, we assume that each individual has a general stress capacity towards all types of specific stress that should not be exhausted. Experimental stress levels are transferred into general stress levels of the SAM using the stress-related mortality as a common link. These general stress levels of independent stressors are additive, with the sum determining the total stress exerted on a population. With this approach, we provide a tool that quantitatively predicts the highly synergistic direct effects of independent stressor combinations.
UFZ - Helmholtz Centre for Environmental Research, Dept. System-Ecotoxicology, Permoserstrasse 15, D-04318 Leipzig, Germany.|RWTH Aachen University, Institute for Environmental Research (Biology V), Worringerweg 1, 52074 Aachen, Germany.
Matthias
M
Liess
UFZ - Helmholtz Centre for Environmental Research, Dept. System-Ecotoxicology, Permoserstrasse 15, D-04318 Leipzig, Germany.
Kaarina
K
Foit
UFZ - Helmholtz Centre for Environmental Research, Dept. System-Ecotoxicology, Permoserstrasse 15, D-04318 Leipzig, Germany.
Saskia
S
Knillmann
University Koblenz-Landau, Institute for Environmental Sciences, Fortstrasse 7, 76829 Landau in der Pfalz, Germany.
Ralf B
RB
Schäfer
University of the Bundeswehr München, Faculty EIT, W-Heisenberg-Weg 39, 85577 Neubiberg, Germany.
Hans-Dieter
HD
Liess
D000818:Animals; D059001:Aquatic Organisms / Q000502:physiology*; D056808:Biostatistics / Q000379:methods*; D004781:Environmental Exposure; D007448:Invertebrates / Q000502:physiology*; D018570:Risk Assessment; D013312:Stress, Physiological; D016019:Survival Analysis