Spatial patterns of ecosystem services and chemical risk assessment in freshwater catchments.

The ecosystem services concept has useful applications in chemical risk assessment, but there is a need to better understand spatial patterns of ecosystem service delivery and chemical risk assessment. With recreational fishery as a case study, a cultural ecosystem service enjoyed by millions of anglers at risk from chemical pollution, this thesis aims to investigate how effects of chemical stressors on a recreational fishery at local scales relate to ecosystem service delivery and risk assessment at the catchment-scale.

This thesis has three main objectives. First, to use a rapid evidence assessment to establish what ecosystem services tools are available. Second, to adapt and use a spatially explicit individual-based model to predict the effects of chemical stressors on a recreational fishery in a river reach. Third, to use the same model to investigate how effects within-reach translate to effects on a catchment-level. Finally, the implications of these findings for both angler satisfaction and ecological risk assessment were considered.

The effects of chemical stress on a recreational fishery varied spatially at the reach, river network, and landscape-scale. Isolated reach populations were most sensitive to stress effects on survival and resistant to effects on fecundity. Fish populations could recover from chemical stress but angler satisfaction decreased under all chemical stress scenarios. Impacts on angler satisfaction were not as apparent on the landscape-scale and spatial patterns did not directly translate from the local reach to the river network. The impacts of chemical stress on angling stock were variable at the local scale and neighbouring reaches could mitigate impacts at the catchment-scale.

Chemical risk assessment would be best applied with a local scale assessment to highlight the impact of chemicals coupled with a wider, landscape-scale assessment to better include dynamics as spatial patterns are useful in understanding chemical effects.