Riverscape correlates for distribution of threatened spotfin chub Erimonax monachus in the Tennessee River Basin, USA

Abstract

Globally, aquatic biodiversity is imperiled at an increasing rate, especially in diversity hotspots such as the southeastern USA. The spotfin chub Erimonax monachus is a federally threatened minnow with a disjunct distribution resulting from numerous impoundments on the Tennessee River and its tributaries in the heart of the southeastern USA. Recovery actions required to remove federal protection for E. monachus are dependent on the establishment of additional populations within the historical range of the species, but little is known regarding macroscale habitat requirements that could guide conservation planning. We analyzed local-and networkscale watershed attributes to develop an ecological niche model (ENM) for E. monachus useful for directing conservation actions at sampled and unsampled sites across the Tennessee River Basin. We found E. monachus occurred most often in larger streams with large upstream catchment areas and minimal alteration to forested uplands, but all of these sites were in close proximity to high densities of downstream dams due to populations being restricted to large-stream habitat upstream of reservoirs. The ENM showed the highest probability of E. monachus occurrence among catchment locations with known extant populations; however, additional historical and previously unoccupied catchments showed potential for successful (re)introductions, provided that fine-scale habitats are appropriate. Our framework can be used to identify potential survey and (re)introduction sites for E. monachus as well as other rare riverine fishes and represents a method for identifying areas of high priority for conserving aquatic biodiversity.

Conservation at the nexus of niches: Multidimensional niche modeling to improve management of Prairie Chub

“…Finally, our results revealed that the highest suitability of Prairie Chub was among large stream fragments with high densities of downstream dams (DMD; Cooper et al 2017). This pattern is consistent with the federally listed Spotfin Chub Erimonax monachus that is essentially isolated upstream of large reservoirs (Perkin et al 2019a) and highlights the lack of downstream connectivity that has already contributed to the decline and extirpation of Prairie Chub (Winston et al 1991).…”

“…The local scale is the area of land draining immediately into an interconfluence stream segment, excluding all upstream segments, whereas the network scale includes the focal segment plus all upstream segments (Hill et al 2017). These two scales have been used in ENMs for freshwater fishes in other studies (Perkin et al 2019a) based on the medium-resolution NHD stream identification code (i.e., COMID), which allows for precise mapping of species distributions. Land use and land cover data included attributes such as agriculture, urbanization, and forested land covers, as well as cumulative habitat disturbance assigned to NHD stream segments by Daniel et al (2019).…”

Temporal distribution modelling reveals upstream habitat drying and downstream non‐native introgression are squeezing out an imperiled headwater fish

“…Segments with both Headwater catfish and Channel catfish were denoted as presence locations (class = 1). The TGA method is commonly used in stream fish species distribution modelling implemented with presence–absence model algorithms (Huang & Frimpong, 2015; Malone et al., 2018; Perkin et al., 2019).…”