POTENTIAL EFFECTS OF GLOBAL CLIMATE WARMING ON BROOK TROUT GROWTH ANDPREY CONSUMPTION IN CENTRAL APPALACHIAN STREAMS, USA

The effects of global warming trends on growth and food consumption ra tes for a brook trout Salvelinus fontinalis population were simulated with a bioenergetics model. We examined the hypothesis that improved g rowth conditions during cooler months will offset the opposing effects of extreme temperatures during the summer. Annual growth increments o f brook trout were determined from a population in a high elevation st ream in West Virginia, USA, and baseline stream temperatures were meas ured in mid to high elevation streams. The mean annual stream temperat ure was increased by 2 and 4 degrees C to simulate the effects of clim atic warming. Brook trout populations at high elevations in the Appala chian Mountains could either benefit from increased growth rates in sp ring and fall, or suffer from shrinking habitat and reduced growth rat es in summer, depending on the magnitude of temperature change and on food availability. An increase of 2 degrees C or less could very likel y increase brook trout growth, but the effect of larger temperature in creases is less predictable due to greater dependence on higher prey p roduction. A 15 to 20% increase in food consumption would be required to maintain present rates of growth with an increase of 2 degrees C, a nd 30 to 40% more food would be required with an increase of 4 degrees C.