Appendix 5
Recent years North Carolina has also seen the largest numbers of very warm nights (Frankson et al. 2022) . The Blue Ridge Ecoregion of North Carolina is projected to experience a reduction in days that drop below freezing (i.e., the number of nights that have minimum temperatures below 32° F): a 17-19% reduction by 2050, and 24-31% reduction by 2075, depending on emission scenario. As low (i.e., nighttime temperatures) rise, some species may also be impacted. Warmer nights can have a profound impact on animal and plant health because temperatures are generally lower at night, normally allowing the environment to cool down. Table 12, Appendix 5 Reference Document 5-2, provides a summary of this information.
Water temperatures
The SAM are a hotspot of aquatic biodiversity such as freshwater crayfish, fish, and mussels and are a region with strong elevational temperature gradients (Pelayo-Villamil et al. 2015; Hossain et al. 2017) . Native aquatic species exhibit a variety of elevational limits and breadths, and therefore associate with different thermal regimes within montane streams (Keck et al. 2014; Troia and Giam 2019) . Some cool-water streams are characterized by highly biodiverse and endemic communities, while others at higher elevations are characterized by one or two cold-water species, such as the culturally and recreationally valuable Brook Trout ( Salvelinus fontinalis ) (Warren et al. 1997; Scott and Helfman 2001) . Water temperature is known to have important effects on various life history traits of aquatic species with species exhibiting specific thermal tolerances (Beitinger et al. 2000; Bennett et al. 2018; Myers et al. 2018) . Consequently, forecasted changes in water temperature are likely to impact aquatic species distributions, including Brook trout, as only slight changes in temperature could promote large shifts in the allocation of production across fish species (Febbe et al. 2006; Ficke et al. 2007; Rahel and Olden 2008; Myers et al. 2018) . A recent study of North Carolina’s cold-water and cool- water streams in Appalachia found that cool-water streams had only a 3.6 °F higher average water temperature in the summer than cold-water streams, and therefore, cold-water fish populations located in cool-water southern Appalachian streams may already rest at the edge of their temperature thresholds (Myers et al. 2018) . Warming water temperature has also increased the prevalence of disease, as warmer temperatures allow disease organisms to complete their life cycle more rapidly and thus attain higher population densities (Paukert et al. 2021) . For example, the nonnative pathogen Myxobolus cerebralix , which causes whirling disease in fish, is likely to increase in impact to fish communities with warming waters (Rahel and Olden 2008) . Fish communities may change as range shifts will likely occur on a species level, not a community level and will add novel biotic pressures to aquatic communities. A recent study found that small-bodied freshwater fishes, such as southern Appalachian minnows (family Cyprinidae) and darters (subfamily Etheostomatinae), are more vulnerable to habitat warming because of their weaker dispersal ability than large-bodied fish (Troia et al. 2019) . In head-water mountain stream habitats, as water temperatures rise, the resilience and persistence of resident cold- and cool-water fish species will be influenced by their capacity for adaptation to novel temperatures or ability to immigrate to more favorable habitats uphill (Wenger et al. 2011) .
2025 NC Wildlife Action Plan
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