Abstract

The eastern hellbender (Cryptobranchus alleganiensis alleganiensis) has experienced widespread declines due to anthropogenic effects. Extreme hydrologic events have recently increased in severity and frequency due to climate change, posing a threat to stream ecosystems; however, there is a lack of research on how these events, such as major floods and hurricanes, impact aquatic species such as eastern hellbenders. In the fall of 2024, Tropical Storm Helene devastated Western North Carolina, bringing floods up to 20 feet above base flow, washing debris and pollutants through waterways. This study assessed pre- and post-Helene eastern hellbender populations from nine reaches across the Upper French Broad Watershed. Sites were sampled prior to the storm in 2023 and 2024 and after in the summer of 2025. Using diurnal rock lift and dive light methods all substrates about six cm or larger were checked, ensuring all life stages were considered. Pre- and post-Helene population estimates were analyzed using paired t-tests to compare estimated abundances of hellbender age classes across all sites, as well as total estimates by site. The adult abundance significantly declined, with an average of one less adult per site. Adult decline raises concern about reproductive and recovery rates. The effects of Helene were site-specific, indicating that further investigation is necessary to identify factors responsible for population changes. Our results suggest that disturbances like Helene may decrease populations, threatening species already at increased risk. This data provides a baseline understanding of hellbender response; however, more research must be done to track population change over time and expand on the different factors influencing populations.

Keywords

freshwater, hellbender

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