The Effect of Episodic Stream Acidification on the Southern Appalachian Brook Trout (Salvelinus Fontinalis)

The Southern Appalachian Brook Trout (Salvelinus fontinalis) are currently undergoing declines in their native ranges; major causes of these declines are episodic stream acidification events. The habitats in which these animals live can regularly experience pH drops of up to 0.5-2.0 units (Neff, Schwartz, Henry, Robinson, Moore, & Kulp, 2009). When environmental pH drops this low, organisms must prevent these acids from affecting their systemic pH. The primary method of accomplishing this is through the use of the ion transporting mechanisms (Claiborne, Edwards, & Morrison-Shetlar, 2002). Previous studies on the Rainbow Trout (Oncorhynchus mykiss) have shown the H+-ATPase and NHE3 to increase expression when exposed to low environmental pH (Perry, Shahsavarani, Georgalis, Bayaa, Furimsky, & Thomas, 2003). It was hypothesized that these ion transporters would be used when Southern Appalachian Brook Trout were exposed to a lowered environmental pH and that the stream sodium level would dictate which transporter was most highly expressed. To date, we have shown the presence of the H+-ATPase and NHE3 transporters in the gills of the Southern Appalachian Brook Trout, as well as suggested that these animals change use of transporter based on current energy level and sodium content of the stream.