Appendix 5
Reference Document 5-3
Many montane fish species and individuals will be less capable of rapid adaptation to temperature change and will experience changes in mortality and production rates (Myers et al. 2017) . This is concerning because the two most species-rich groups of fish of North Carolina’s montane habitats are minnows and darters and forecasted to be less likely to keep pace with upstream shifts in thermally suitable habitats (Troia et al. 2019) . However, thermal stress may be moderated from changes in precipitation by increasing flows to create deeper habitats and increase thermal refugia for Brook trout within Appalachian streams (Merriam et al. 2017) . Both temperature and precipitation patterns, and their influence on montane fish life history across time must be considered as they form a delicate balance that can both support and limit cold- water fish populations in headwater streams (Andrew et al. 2022) . Aquatic invertebrates of North Carolina’s mountain habitats, such as freshwater mussels, fish, and crayfish, are also experiencing thermal stress as climate change increases average water temperatures and extends the summer season (Waller and Cope 2019; van Ee et al. 2022; Fogelman et al. 2023a) . However, the thermal physiology limits (what temperatures a species can endure) of most of these aquatic species remains unknown. This precludes our understanding of historical elevational limits and prevents accurate forecasts of upslope species shifts under future climate change. For example, a global review for thermal tolerance of freshwater crayfish concluded that thermal tolerance data are available for only 6% of species worldwide, attributing this mostly to the fact that many species are understudied and data-poor (Westhoff and Rosenberger 2016) . Aquatic ectotherms (i.e., cold-blooded animals) such as crayfish are particularly vulnerable to changes in thermal regimes as temperature is a critical factor regulating life history traits such as reproduction, distribution, and mortality (Ern et al. 2015; Westhoff and Rosenberger 2016; Cereja 2020; Fogelman et al. 2023a & b) . Only two species of North Carolina’s montane freshwater mussels have been evaluated for their lethal thermal tolerances: the Brook Floater ( Alasmidonta varicosa ) and Eastern Creekshell ( Villosa delumbis ) (Pandolfo et al. 2010; Fogelman et al. 2023a) . More physiological research, such as identifying thermal limits, on North Carolina’s aquatic montane species are needed to determine their sensitivity to warming waters in the mountain habitats. As some geographic regions are predicted to see increased rates of warming, such as Appalachia, it is important to evaluate the thermal tolerances of mussels within these faunal regions as they have high degrees of endemism to the SAM of North Carolina (Fogelman et al. 2023a) . Adaptation strategies for endemic crayfish have been developed by Taylor et al. (2019). Increasing stream temperatures have also been linked to other dangerous stressors for aquatic freshwater mountain fauna. Dissolved oxygen concentrations in water are essential for the survival of aquatic animals for respiration. Cold mountain streams exhibit higher dissolved oxygen concentrations than warmer ones, supporting species like Brook trout that thrive in well-oxygenated waters. Warming water results in less oxygen in the water, a process called deoxygenation. A recent study revealed persistent warming in 87% and deoxygenation in 70% of 580 rivers across the US (Zhi et al. 2023) . Lower dissolved oxygen concentrations or hypoxia (resulting in ‘dead zones’) could induce acute death and sublethal negative health effects for cold-water fishes, such as trout and darters, in montane habitats (Zhi et al. 2023) .
2025 NC Wildlife Action Plan
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