New ecotoxicological model to simulate survival of aquatic invertebrates after exposure to fluctuating and sequential pulses of pesticides.
Aquatic nontarget organisms are exposed to fluctuating concentrations or sequential pulses of contaminants, so we need to predict effects resulting from such patterns of exposure. We present a process-based model, the Threshold Damage Model (TDM), that links exposure with effects and demonstrate how to simulate the survival of the aquatic invertebrate Gammarus pulex. Based on survival experiments of up to 28 days duration with three patterns of repeated exposure pulses and fluctuating concentrations of two pesticides with contrasting modes of action (pentachlorophenol and chlorpyrifos) we evaluate the new model and compare it to two approaches based on time-weighted averages. Two models, the Threshold Damage Model and the time-weighted averages fitted to pulses, are able to simulate the observed survival (mean errors 15% or less, r2 between 0.77 and 0.96). The models are discussed with respect to their theoretical base, data needs, and potential for extrapolation to different scenarios. The Threshold Damage Model is particularly useful because its parameters can be used to calculate recovery times, toxicokinetics are separated from toxicodynamics, and parameter values reflect the mode of action.
Ashauer
Roman
R
Environment Department, University of York, Heslington, York YO10 5DD, United Kingdom. r.ashauer@csl.gov.uk
Boxall
Alistair B A
AB
Brown
Colin D
CD
D033304:Amphipoda / Q000187:drug effects; D000818:Animals; D004390:Chlorpyrifos / Q000633:toxicity*; D007928:Lethal Dose 50; D008954:Models, Biological; D010416:Pentachlorophenol / Q000633:toxicity*; D010575:Pesticides / Q000633:toxicity*; D018570:Risk Assessment; D014874:Water Pollutants, Chemical / Q000633:toxicity
D010575:Pesticides; D014874:Water Pollutants, Chemical; D010416:Pentachlorophenol; D004390:Chlorpyrifos