Effects of chemicals on ecosystems: extrapolating from individuals to ecosystem function

Chemicals released into the environment can have adverse effects on ecosystems and the benefits they provide to people (i.e. ecosystem services). However, current regulatory approaches largely fail to provide the scientifically robust evidence required to optimise the trade-off between societal benefits and environmental impacts of chemical use. This is because the tools needed to assess the risks to ecosystem functions and the ecosystem services we wish to protect do not exist. In order to effectively manage chemicals in the environment and protect the ecosystem services on which we depend, there is an urgent need to develop approaches that enable the extrapolation of measurements of the effects of chemicals on individual organisms to ecosystem functions and, hence, to the ecosystem goods and services they support. This project will begin to address this need.

Most studies measure the effect of chemicals on individual organisms and do not consider impacts on the population characteristics and ecological processes. Scientific experts from European regulatory authorities, the chemical industry and academia have recently evaluated the implementation of an ecosystem services approach to the ecological risk assessment of chemicals [1]. They concluded that a major limitation to adopting this approach was the inability to link endpoints derived from current toxicity tests to impacts on ecosystem function and ecosystem services. Also, the need to develop mechanistic models to extrapolate adverse effects across different levels of biological organization (e.g. individual to population) was rank 4th in a recent prioritization of research needed for sustainable environmental quality in Europe [2]. Feeding inhibition is a sensitive and general response to chemical exposure that is linked to important ecological functions including nutrient cycling and pest control. Individual-based dynamic energy budget models (DEB-IBM models) can be used to extrapolate chemical-induced reductions in invertebrate feeding to population abundance and to incorporate the impact of chemical-induced changes in resource availability.

The aim of this project is to combine ecological understanding and modelling to develop approaches for extrapolating from individual-level measurement endpoints derived in toxicity tests to the potential risk to ecosystem functions and the services they deliver. The specific objectives are to:
1. generate dynamic energy budget models for a range of freshwater invertebrates that vary in their sensitivity to environmental pollutants.
2. calibrate models using information using a database of invertebrate community data from over 700 minimally impacted freshwater sites.
3. quantify the effect of exemplary chemicals on the feeding rate of the study species
4. use the models to predict changes in population dynamics and ecosystem function from information on chemical-induced feeding inhibition.
5. To use models to explore the relationship between the individual-level effect of chemical exposure and risk to ecosystem services.

The post would suit a motivated student interested in ecological modelling, with enthusiasm for a mix of laboratory and computer-based work. This is a CASE studentship with Syngenta.