Arrow darter

Abstract: The Kentucky Arrow Darter (KAD), Etheostoma spilotum, is an endemic species to the Upper Kentucky River Basin and is currently proposed for listing as threatened under the Endangered Species Act. The ecology and population status of this benthic species is poorly understood, so this study was designed to investigate the species’ movement capabilities, population dynamics, and overall ecology in two streams (Gilberts Big and Elisha Creek) in the Red Bird Ranger District, Daniel Boone National Forest, Kentucky. Project objectives included quantification of movement patterns, identification of microhabitat use, and estimation of population size in both streams. Sampling was conducted during three seasons (spring summer, and fall) in 2013 utilizing a probabilistic sampling design, with a total of 752 microhabitat plots being sampled from 23 reaches across those seasons. Utilizing passive integrated transponder (PIT) tags for continuous tracking, movements of 121 KADs ranged from 28-4,078m in both up and downstream directions. Population estimates ranged from 80-1498 individuals but varied depending on stream and season, with the spring season yielding the lowest estimate. Habitat associations between occupied and unoccupied reaches and plots were compared both seasonally and across all seasons. Results suggested that pool habitats with cobble, higher mean depths, and lower composition of sand, gravel, and boulders were more commonly associated with KAD presence.

Abstract: This study presents a geographic information system (GIS)-based predictive habitat suitability model for the Kentucky arrow darter (Etheostoma spilotum), a fish species of the upper Kentucky River system that is a candidate for federal listing by the U.S. Fish and Wildlife Service. Five habitat factors were identified by experts for modeling the habitat: gradient, canopy coverage, land cover, riparian zone width, and stream order. Using a GIS, values for the five habitat factors were calculated and then combined for all stream segments of the upper Kentucky River system at 100-m intervals. Habitat factor combinations were assigned an overall habitat suitability rating using a weighted calculation system derived through input from aquatic biologists. The resulting model was tested against presence data using locational modeling statistics. A total of 97.33 percent of occurrences were located in the two higher rated categories of habitat suitability. Only two occurrences were located on stream segments of t...

Abstract: This study presents a Geographic Information Systems (GIS)-based predictive habitat suitability model for the Kentucky arrow darter (Etheostoma spilotum), a fish species of the upper Kentucky River basin that is a candidate for federal listing by the U.S. Fish and Wildlife Service. The model is based on previous work: the development of a similar predictive model for identifying the habitat of the blackside dace, a threatened minnow species of the upper Cumberland River basin in Southeastern Kentucky. The research describes a weighted, rules-based system which incorporates expert knowledge about habitat preferences for the arrow darter. For this model, five habitat factors were identified by experts as essential to modeling the habitat: stream gradient, canopy coverage, land cover, riparian zone width, and stream order. Using a GIS, the five habitat factors were parameterized and combined across the entire Kentucky River basin stream network. Experts evaluated combinations of habitat factors to determine habitat suitability. Using locational modeling statistics, the resulting model was tested against known Kentucky arrow darter occurrences. The analysis demonstrated successful identification of streams where the arrow darter was likely — and unlikely — to exist. Model results could be useful to transportation planners, particularly when determining sensitive landscape that could be impacted by transportation planning processes. This model may help planners save money on habitat mitigation when transportation initiatives take place in known unsuitable arrow darter habitats. A GIS model similar to the one developed in this study may be applicable to other endangered species.

Abstract: The Kentucky Arrow Darter (Etheostoma sagitta spilotum) is federally listed as threatened and known only from five tributary systems in the Kentucky River system, Kentucky, USA. Recent surveys revealed considerable population decline, with individuals detected in only 45% of known historical localities. Impacts of these declines on the genetic structure of E. s. spilotum may be exacerbated by limited dispersal capabilities and small initial population size resulting in high levels of isolation among extant populations. Long standing genetic isolation may also be evident in contemporary genetic signatures; populations that have undergone historic isolation may be prime candidates for intensive conservation efforts. To address contemporary and historic genetic isolation, we generated genotypic (11 microsatellite loci) and mtDNA sequence (ND2 gene) data from multiple locations spanning the taxon’s range. We recovered seven haplotypes with low divergence levels, shared among and within multiple Kentucky River tributary systems, indicating absence of long-standing isolation among localities examined. In contrast, microsatellite data suggested all nine populations are functionally isolated, with little to no admixture among populations, even among those within the same tributary system. The drastic decline of E. s. spilotum populations has likely combined with limited dispersal, resulting in extensive contemporary genetic isolation among extant populations. Conservation management plans to enhance stability and maintain survivability of E. s. spilotum must address the severe genetic isolation identified here and work towards increasing gene flow among extant populations.