Environmental stress enhances the effects of pollutants

Environmental stress enhances the effects of pollutants

Each and every organism on Earth is exposed to the influence of various environmental conditions and of other living organisms. These factors can trigger stress and make the living organism more vulnerable to external influences. A team of researchers has now succeeded in using aquatic organisms to demonstrate that the presence of environmental stress multiplies the effects of pollutants on organisms. Furthermore, they have developed a model that makes it possible to use the intensity of the environmental stress as a basis to predict the increased impact of pollutants.

Each and every organism on Earth is exposed to the influence of various environmental conditions and of other living organisms. These factors can trigger stress and make the living organism more vulnerable to external influences. A team headed by researchers from the Helmholtz Centre for Environmental Research has now succeeded in using aquatic organisms to demonstrate that the presence of environmental stress multiplies the effects of pollutants on organisms. Furthermore, they have developed a model that makes it possible to use the intensity of the environmental stress as a basis to predict the increased impact of pollutants. They published their findings in the Scientific Reports journal.

Animals and plants are simultaneously exposed to a multitude of natural and human-made ("anthropogenic") stressors. These may arise, for example, from the lack of water associated with competition for food, infestation with parasites or confrontation with environmental chemicals such as pesticides. It is known from all fields of ecology that such simultaneous effects of a variety of stressors can have great implications for plants and animals within an ecosystem, while, individually, the stressors trigger virtually no discernible effects.

As now demonstrated by the findings of the research team from the Helmholtz Centre for Environmental Research (UFZ), the University of Koblenz-Landau and the Bundeswehr University, Munich, the presence of environmental stress can multiply the effects of pollutants by a factor of up to 100.

In order to devise measures aimed at preserving biodiversity in a more effective and targeted manner, the ability to predict what impact a combination of different stressors has on individual populations is really important in any case. It therefore comes as a surprise that, despite a large number of research papers centring on this topic and the awareness of the impact of individual stressors, there is, to date, no universal approach to such predictions of their effects as an entirety.

Thanks to these research findings, it will now be possible to make predictions of this kind, confirms Prof. Dr. Matthias Liess of UFZ who headed the study: "We have developed a model that allows us to calculate the overall quantitative stress exerted on an organism. We achieved this by determining the interrelationships among the individual stressors and also taking account of individual stress capacity in this context." This factor does vary considerably between the organisms contained in a population; most of them have a medium level of stress capacity, some cannot cope with even a low level of stress, and others stand up to high levels of stress without any problems.