Pattern of invasion by Weed Shiner (<Emphasis Type="Italic">Notropis texanus</Emphasis>), a nonindigenous cyprinid in the Bear Creek system (Tennessee River drainage), USA

Invasive species increasingly threaten global biodiversity with faunal homogenization, and are of specific concern in the highly diverse aquatic systems of the Southeast United States. However, patterns of invasion and variables influencing invasion success remain poorly understood. This study followed the introduction, establishment, and invasion processes of nonindigenous Weed Shiner (Notropis texanus, Family: Cyprinidae), and examined environmental correlates of their persistence. Potential shifts in the native fish assemblage in Bear Creek, Alabama and Mississippi, USA, due to Weed Shiner presence were also investigated. Assemblage shifts were evaluated using Jaccard and Morisita similarity indices and nonmetric multidimensional scaling (NMDS) ordination. Weed Shiner exhibited an initial rapid expansion in range and abundance, followed by a range contraction in 2012, and range and abundance decline in 2013 and 2014. Weed Shiner persists at the most human-impacted, downstream sites in Bear Creek. Similarity indices and NMDS indicated that despite rapid initial proliferation of Weed Shiner, native fish assemblage did not significantly change. Rather, the native fish assemblage structure in Bear Creek is temporally variable and influenced by watershed area, land-use, high intensity development, mixed-hardwood forest and evergreen forest (pine monoculture). Limiting future Weed Shiner impacts in the system and successful conservation of the Bear Creek fish assemblage will rely on managing land use changes and mitigating development effects in the watershed.