Long-term change in the suitability of welsh streams for dippers Cinclus cinclus as a result of acidification and recovery: a modelling study

Using a recognized and widely used hydrochemical model, MAGIC, long-term changes in acidity were simulated at 104 sites in the acid sensitive region of upland Wales. Conditions were modelled in the future (2010) under different reductions in sulphate deposition from 0 to 90% of 1984 values. Chemical output from the model was used to simulate change in the chemical suitability of streams for a species of river bird, the Dipper Cinclus cinclus, known to be affected by acidification According to simulations, only reductions in sulphate deposition by over 50% of 1984 levels prevented decline in the number of streams chemically suitable for Dippers. Greater reductions in deposition in the model permitted some recovery except where conifer forestry occupied acid sensitive catchments. There are several uncertainties with the models in their present form.