Acid runoff caused fish loss as an early warning of forest decline

Sulfate, nitrogen, and hydrogen ion deposition in the Laurel Hill region of the Appalachian Plateau province in Pennsylvania has been very high. Records indicate that losses of rainbow trout (Oncorhynchus mykiss) first occurred about 1960, although unrecorded losses probably preceded that date. Research has also attributed loss of brook trout (Salvelinus fontinalis) in this region to chronic and episodic stream acidification. Relatively recently, mortality of northern red oak has become a problem in parts of the region with mortalities as high as 60 percent of standing trees evident in some areas. Preliminary analysis indicates that soil acidification may play a significant role in the observed mortality. If this is the case, it would appear that fish losses due to watershed acidification in the region were evident about 30 years prior to the current mortality of northern red oak. Therefore, fish loss caused by acidification may be a prelude to more widespread ecosystem damage as a consequence of chronic deposition of acidifying elements.