Ecological risk assessment and food webs: multiple stressor effects on biodiversity and ecosystem function

Ecological risk assessment is used to determine the likelihood of adverse ecological effects resulting from human impacts on the environment. Most regulatory toxicity studies measure the effect of chemicals on individual organisms and do not consider impacts on higher levels of biological organisation, including biodiversity, ecosystem function and ecosystem services.

The assumption is that by basing the regulatory decision on individual-level endpoints of sensitive taxa exposed to single chemicals under standardised conditions, the biodiversity and ecological functions of ecosystems that deliver ecosystem services will also be protected.

Although regulatory assessments based on standard toxicity studies are intended to be protective of ecological biodiversity, they are not intended to be predictive nor is there any supportive evidence of how protective they are of ecosystem function There is a need, therefore, to develop approaches that enable the extrapolation of what has been frequently measured (i.e. the effects of single chemicals on individual organisms) to what we want to protect (i.e. biodiversity and ecosystem functions underpinning ecosystem service delivery) and that consider the risk of chemicals in a more realistic, multi-stressor context. This is an important and fundamental objective for ecotoxicological research, especially in the context of global climate change.