FIELD ACUTE TOXICITY METHOD FOR THE ASSESSMENT OF ACID-MINE DRAINAGE USING MACROINVERTEBRATES

An experimental flow through chamber was designed and tested to evalua te a field toxicity method for rivers receiving acid mine drainage. It was found to produce reliable and reproducible results. Three test ma cro-invertebrates were evaluated Gammarus duebeni, Ephemerella ignita and Baetis rhodani. Only the former species proved both robust and sen sitive enough for toxicity assessment work using the chambers. While t he field toxicity tests indicated that only the mixing zone was impact ed, routine biological surveillance has shown the impact to be on a mo re extensive scale with the entire river below the mines and into the estuary (12km) severely damaged. These results suggest that factors ot her than water toxicity are responsible for the elimination of species in the lower Avoca, although the water quality may result in long ter m chronic toxicity.