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Stream mitigation is widely used to offset and restore anthropogenic stream degradations, yet ecosystem health is not always improved. Specific mitigation type may play a role in the potential for biotic improvement, with differing common mitigation practices including restoration and habitat enhancement. By looking at small factors in stream communities, such as macroinvertebrates, a larger connection can be made to the overall biotic integrity and quality of the aquatic habitat. This study used a Before-After-Control-Impact design to evaluate changes to biotic integrity of four streams in western North Carolina that underwent either complete restoration or habitat enhancement as compensatory mitigation under provisions of the United States Clean Water Act. We developed a Habitat Quality Improvement Index (HQII) to compare macroinvertebrate family-based metrics of habitat quality between 2011 (pre-mitigation) and 2021 (post-mitigation) and used a multivariate analysis to examine changes in macroinvertebrate family composition at each site. Analysis of HQII values using a Monte Carlo resampling procedure showed significant improvement at restored sites, whereas habitat quality declined significantly at sites that underwent habitat enhancement only. Our results indicate that restoration practices can have positive impacts on stream health, especially where habitat degradation is localized, and macroinvertebrate populations at high-quality upstream sections can provide a source for recolonization once habitat conditions improve. [ABSTRACT FROM AUTHOR]

The Eastern Hellbender (Cryptobranchus alleganiensis alleganiensis) is a large aquatic salamander found in cool, highly oxygenated rivers and streams of the eastern United States. Hellbender populations have been steeply declining over the past century, and they are a protected species in many states, including North Carolina where they are listed as a species of special concern. North Carolina contains over 2,000 waterways that could potentially support hellbender populations. It is vital to survey these waterways to better understand the distribution of the Eastern Hellbender and the environmental factors necessary to support populations. Although small streams could potentially act as refugia for both larval and adult hellbenders, most surveys have focused on large rivers, generally using substrate composition and cover rock presence as site selection determinants. In early summer of 2013, we surveyed Bent Creek, a small (25.3 km²) catchment in the Pisgah National Forest beginning at the confluence with the French Broad River and concluding upstream to the Lake Powhatan dam. We documented four adult Eastern Hellbenders, including two captures and two tactile encounters/escapes. These represent the first records for C. a. alleganiensis in this catchment. In October 2013, we compared the number of cover rocks, water temperature, dissolved oxygen and substrate composition of three occupied and three unoccupied stream reaches. Although temperature and dissolved oxygen did not vary among reaches, occupied stream reaches had coarser substrates and amuch higher occurrence of cover rocks than unoccupied reaches. Our findings suggest that commonly used surveying techniques relying on potential cover rocks and substrate composition are effective methods for selecting survey sites. Future research could examine whether the Eastern Hellbender population at Bent Creek is, or has the potential to become, a viable breeding population, as well as assessing population size upstream from Lake Powhatan. Suitability of stream conditions to consistent larval recruitment should also be evaluated. Our findings suggest that smaller streams such as Bent Creek can support viable populations of C. a. alleganiensis, and that restricting surveys to largerwatersheds has the potential to miss important populations of this imperiled species. [ABSTRACT FROM AUTHOR]

We investigated the attributes of shelters used by Eastern Hellbenders (Cryptobranchus alleganiensis alleganiensis) in two 500-m stretches of the French Broad River basin in North Carolina during June 2010. We quantified attributes at each Hellbender shelter and at a corresponding unoccupied shelter located <25 m away to determine whether the attributes selected differed from those available in the surrounding environment. We identified 41 Hellbender shelters, each occupied by a single animal. Hellbenders selected shelters that had larger cover rocks and deeper cavities than the unoccupied shelters. No other attributes differed between occupied and unoccupied shelters, and there were no significant relationships between total length of Hellbenders and size of the cover rock or cavity depth. All Hellbender shelters were formed by large rocks with flat bottoms. Most had a single entrance that was oriented downstream and a cavity floor consisting of sand and gravel. Shelters were generally located in shallow, fast-flowing water with <10% of their surface area embedded in the substrate. Our results suggest that Hellbenders prefer shelters with attributes that maximize cavity space. Larger cavities likely provide greater protection from predators and greater concealment from sunlight. In addition, larger cavities allow more space for Hellbenders to rock back and forth to maximize oxygen uptake through their skin during periods of low flow when oxygen levels drop. [ABSTRACT FROM AUTHOR]