THE EFFECTS OF AN ABANDONED ROAST YARD ON THE FISH AND MACROINVERTEBRATE COMMUNITIES OF SURROUNDING BEAVER PONDS

Recently formed beaver-ponds surrounding an abandoned copper-nickel or e roast yard near Sudbury, Ontario, Canada, were influenced by highly acidic and heavy-metal contaminated effluent. Fish, including Culaea i nconstans, Phoxinus neogaeus, Phoxinus eos, and Pimephales promelas, w ere found in the ponds upstream of the roast yard only. Macroinvertebr ate taxon richness and diversity were greater in the upstream ponds th an in the downstream ponds. Acid intolerant taxa, including Mollusca a nd Hyalella azteca, were found upstream only; acid tolerant taxa, incl uding Enallagma and Ishnura (Odonata: Coenagrionidae) were found in th e downstream ponds. One taxon, a species of Chironomus, was especially tolerant of both acid and metal stresses, and was the only invertebra te taxon found in the pond located directly on the roast yard itself. We conclude that long-abandoned mining and refining sites can continue to have a marked effect on aquatic communities.