Current, reconstructed past, and projected future status of brook trout (Salvelinus fontinalis) streams in Virginia

Abstract

Southern Appalachian streams host a rich diversity of fishes, but the Southern Appalachian Assessment concluded that 70% of stream locations showed significant fish community degradation, partly due to acid deposition. About 40% of total Southern Appalachian trout stream length occurs in Virginia. Our research in Shenandoah National Park, Virginia, has documented both chronic and episodic acidification in streams and brook trout (Salvelinus fontinalis) mortality during acid episodes. Here, we analyze a representative sample of 60 Virginia brook trout streams on noncarbonate bedrock with minimal human disturbance in their watersheds. Of more than 300 such streams in Virginia, only about 50% are currently suitable for brook trout, based on their acidification status. For the population of brook trout streams to which this analysis applies, model-based projections indicate that continued sulfate deposition at 1991 levels will result in about 70 additional streams becoming chronically acidic and unsuitable for brook trout. A 40% reduction will result in about 48 additional chronically acidic streams. Even a 70% reduction will likely result in about 15 additional streams becoming acidified. We conclude that reductions in sulfate deposition greater than 70% (relative to 1991 levels) are needed to prevent more brook trout stream losses in Virginia.