LRI AWARD 2005: Predicting the response of aquatic invertebrates to stress using species traits and stressor mode of action

Description

In the field of ecotoxicolgy the quantification of differences in species susceptibility to toxic substances is mainly estimated using statistical approaches. Although these approaches are very useful for use in Environmental Risk Assessment, they aim at quantifying the variation in species sensitivity rather than understanding it; i.e. it remains uncertain which species will be affected. Surprisingly little attention has been paid to the question WHY species differ in their sensitivity to stressors. A mechanistic understanding of the relation between species properties and traits and the stressors mode of action could answer explain the variability in species sensitivity and be the first step to reduce its uncertainty. So the central theme of the project is the development of a new methodology that identifies the ecological risk posed by single stressors using species traits by linking our understanding of species characteristics (e.g. body size, mode of reproduction, dispersal ability) with knowledge of species sensitivity to stressors (e.g. toxicity databases, ecophysiology literature). The main achievement of this work will be an increased insight into the factors that determine the response of species to chemical stressors. This will lead to a better estimation of the uncertainty associated with species sensitivity and thereby to better risk assessment methodology.
In the light of the Water Framework Directive, in recent years huge effort has been made to improve biomonitoring and assessment methods to more efficient tools for aquatic environmental management, especially in case of macroinvertebrates. As mentioned above, species sensitivity towards stressors could be seen as a function of various species properties and traits. If so, the most important properties and traits should be defined for classified ecosystems and the variation of these traits among the invertebrate kingdom assessed. By doing so one can be able to translate the biomonitoring measurement endpoint (which is community composition defined by abundance of species) to a more meaningful assessment endpoint, the composition of important species traits, which hypothetically represent the causal basis for varying species sensitivity. From this, the species traits that are over- and underrepresented at a certain sampling site compared to a pristine reference site can be assessed and a possible stressor as a cause identified.