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Box 3 -1. A detailed assessment of the potential impact of climate change on brook trout Brook trout (Salvelinus fontinalis), sometimes called the Eastern brook trout, are one of the most popular gamefish in the Northeast (Crossman and Scott 1973 in Roberts 2000), and the only trout species native to North Carolina (Southern Division American Fisheries Society Trout Committee (SDAFSTC) 2005). Because brook trout are coldwater fish, they are extremely sensitive to changes in stream temperature, particularly in their southern and lower elevation ranges. The upper thermal tolerance for brook trout is 72.3 °F (Eaton and Shell- er 1996) and maximal weight gain in juveniles occurs at temperatures less than 65 °F (McCormick et al. 1972). As of 2002, only 24% of potential stream locations nationwide were cool enough to support brook trout (O'Neal 2002). In addition, average summer stream temperatures at sites across the U.S. are projected to rise 0.7 -1.4 °F by 2030, 1.3 -3.2 °F by 2060, and 2.2 -4.9 °F by 2090 (O'Neal 2002), potentially shrinking the already much - diminished available habitat for brook trout by 26-41% by 2090 under the higher emissions scenarios. Although this study focused on the impacts of climate change on water temperature, other potential climate change effects may have a significant impact on the amount and quality of available trout habitat, including the magnitude or timing of precipitation, evaporation rates, or stream flow changes. Additional secondary effects of climate change, such as the impact of warming waters on food supply, water quality, pesticide toxic- ity or disease, may impact the viability and persistence of brook trout in North Carolina, although further research is clearly needed. Brook trout may also face demographic threats as populations become ever more confined to the highest elevation and coldest streams. The loss of this widely popular recreational species from North Carolina waters could have a significant impact on local and regional economies (Responsive Management 2009). ,, ' Change Fl 1r o'ect111i`o ,wm fror° NoII "th ° a1a' °oill'IC'lr'o Climate Wizard (Zganjar et al. 2009) can also be used to derive middle and end of century precipi- tation projections for North Carolina. Unlike the temperature projections shown in the previ- ous section, which vary in the magnitude but not the direction of effect among models, precipitation projections provide divergent results in the direction (wetter or drier) of change. One way to visualize this is to look at the range of projections generated by the ensemble models (Figure 3 -6). The lowest 20% of projected values from the ensemble suggest less precipitation across the state; whereas the highest 20% of projected values from the ensemble suggest more precipitation, although there appears to be less variability in some seasons than others. Although the seasonal ensemble averages suggest that coastal areas may be drier in the spring and wetter in the fall and winter, with less variability in the western portion of the state (Figure 3 -7), caution should be used in interpreting results from ensembles for which there is high disagreement among the input models. Seasonal averages are also likely to be less biologically relevant to many organisms, which are often more influenced by increased variability and changes in the timing and amount of precipitation during particu- lar time periods, rather than changes in the magni- tude of seasonal averages. The guidance provided by Climate Wizard cautions that projections should be used for making climate decisions only in areas with high model agree- ment (Zganjar et al. 2009), which is often not the case when assessing future projected precipitation. 60 Chapter 3: Projected Impacts of Climate Change in North Carolina