PARENT SESSION
WA2 Assessing and predicting toxicant effects in an ecologically complex world
9:00 AM to 12:30 PM, Wednesday, 09 May 2001
Session Chair: P. Calow, V. Forbes
Room 2

(300) From mesocosms to metapopulations: developing approaches to assess aquatic risks of pesticides in ecologically complex agroecosystems.

Maund, Steve¹, Hamer , Mick ¹, Hendley, Paul², Kedwards, Tim¹, Tattersfield, Lisa¹, Warinton, Jacqui¹, ^{1 2}

ABSTRACT- As a first step to identifying potential concerns in pesticide aquatic risk assessment, laboratory toxicity data with representative species and sensitive life-stages are compared to extreme worst-case exposure scenarios. From an ecological perspective, these assessments are simplistic, but by applying a safety factor they generally appear to have the advantage of being conservative. When concerns are identified, further consideration of the potential for effects in the environment is required. A number of possible approaches to such higher-tier risk assessment in the EU have been proposed. These have tended to focus on the 'toxicological' aspects of ecotoxicology (e.g., refining 'effect' concentrations under more realistic exposure, species sensitivity distributions), rather than more 'ecological' components (although micro- and mesocosm studies do address some aspects of ecological complexity). Put simply, ecology is the study of organisms in their 'homes'. For a more ecological approach to ecotoxicology, we need to consider not just the attributes of organisms themselves (although there is much to do in this respect) but also consider how their home environment (at a number of spatial and temporal scales) could influence the impacts of a pesticide. This raises a number of broader issues: What are the characteristics of aquatic habitats in agroecosystems? Which organisms are associated with those habitats? How is the organism likely to be exposed in such habitats? What do those organisms do, when are they present, where and how do they live, and can we understand how that might influence pesticide impacts? Examples of how we might begin to include such considerations in aquatic risk assessment for pesticides in the future will be presented.

Key words: ecology, aquatic, risk, pesticides