Spatial Modeling to Project Southern Appalachian Trout Distribution in a Warmer Climate

Abstract

Abstract.-In the southern Appalachian Mountains, the distributions of native brook trout Salvelinus fontinalis and introduced rainbow trout Oncorhynchus mykiss and brown trout Salmo trutta are presently limited by temperature and are expected to be limited further by a warmer climate. To estimate trout habitat in a future, warmer climate, we produced a regional map of wild trout habitat based on information from stream samples, expert knowledge, and suitable land cover. We then developed a quantile regression model of the elevation-latitude boundary for the present distribution of trout; this constitutes a more direct, spatially explicit approach to modeling trout distribution than the use of thermal limits. In combination with a lapse rate model, the boundary model was used to project future wild trout distributions over a range of higher temperatures. If the predictions of the Hadley Centre global circulation model (GCM) are assumed, about 53% of trout habitat would be lost; if the more extreme Canadian Centre GCM is used, 97% would be lost. With increasing temperature, fragmentation would increase, leaving populations in small, isolated patches vulnerable to extirpation because of the decreased likelihood of recolonization. The regional trout habitat map and the models produced here were useful for making these predictions, and the map could be used for assessing the impacts of other regional stressors.

Effects of climatic variability and change on forest ecosystems: a comprehensive science synthesis for the U.S

“…A combination of higher air temperature and lower water quality may significantly reduce trout abundance across the southeast during the coming decades (Flebbe et al 2006). …”

Summer temperature variation and implications for juvenile Atlantic salmon

“…As a result of deforestation, agriculture, and urbanization within a watershed, temperatures can increase even in less-developed areas (Poff et al, 1997). Thus, in areas that marginally support coolwater species, direct alterations within the watershed or indirect alterations through global climate change could reduce fish distribution (Eaton & Scheller, 1996;Flebbe et al, 2006;Crozier et al, 2006;Preston, 2006).…”

Potential impacts of climate change on brook trout (Salvelinus fontinalis) populations in streams draining the Laurel Hill in Pennsylvania

“…The resulting fragmentation would confine remaining populations to small isolated patches vulnerable to extirpation due to loss of avenues of connectivity for potential colonizers (Fleebe et al 2006;Letcher et al 2007). The strong correlation between air/stream temperatures in the cool-water receiving streams (Figure 8) indicates potentially narrowing windows for movement of brook trout and other cold-water species through their respective tributary networks, creating the potential for genetic isolation.…”