Jamie Roberts

Georgia Southern University | GSU · Department of Biology

Projects to assess environmental impact or restoration success in rivers focus on project-specific questions but can also provide valuable insights for future projects. Both restoration actions and impact assessments can become "adaptive" by using the knowledge gained from long-term monitoring and analysis to revise the actions, monitoring, concept...

A common strategy for recovering endangered species is ensuring that populations exceed the minimum viable population size (MVP), a demographic benchmark that theoretically ensures low long-term extinction risk. One method of establishing MVP is population viability analysis, a modeling technique that simulates population trajectories and forecasts...

Spatial population structure plays an important role in species persistence, evolution and conservation. Benthic stream fishes are diverse and frequently imperilled, yet the determinants and spatial scaling of their population structure are understudied.We investigated the range‐wide population genetic structure of Roanoke logperch (Percina rex), a...

The dispersal ecology of most stream fishes is poorly characterised, complicating conservation efforts for these species. We used microsatellite DNA marker data to characterise dispersal patterns and effective population size (Ne) for a population of Roanoke logperch Percina rex, an endangered darter (Percidae). Juveniles and candidate parents were...

The reticulated flatwoods salamander (Ambystoma bishopi), an endangered species endemic to the longleaf-pine savanna ecosystem of the southeastern U.S., persists in a small number of remnant habitat patches. Breeding ponds and associated populations are threatened by habitat loss, degradation, and fragmentation stemming from fire suppression and la...

A correction to this paper has been published: https://doi.org/10.1007/s10592-021-01367-w

Reticulated flatwoods salamander (Ambystoma bishopi) populations began decreasing dramatically in the 1900s. Contemporary populations are small, isolated, and may be susceptible to inbreeding and reduced adaptive potential because of low genetic variation. Genetic variation at immune genes is especially important as it influences disease susceptibi...

Roanoke bass (Ambloplites cavifrons) persist in five river basins in the eastern US, where they are threatened by invasive species, habitat loss and degradation, and hydrologic fragmentation. We conducted the first conservation genetic study of A. cavifrons, analyzing variation at 19 nuclear microsatellite DNA loci and the cytochrome b mitochondria...

Environmental DNA (eDNA) studies show great promise for non-invasive surveys of aquatic organisms, but should account for imperfect detection and the influences of biotic and abiotic conditions on detection. We evaluated an eDNA protocol for Roanoke logperch (RLP) Percina rex, an endangered fish of the eastern United States occupying habitats rangi...

North American sunfishes (Centrarchidae) are frequently introduced beyond their native ranges, where they may negatively impact and eventually replace native taxa through a combination of competition and hybridization. Congeneric centrarchids often lack reproductive isolating barriers and appear particularly susceptible to hybridization, though the...

The raccoon (Procyon lotor) is an ecologically important mesopredator that threatens at least 11 species of beach-nesting and colonial waterbirds on the Virginia barrier islands. An understanding of population dynamics, reproductive sources and sinks, and dispersal pathways among the islands and the adjacent Delmarva Peninsula mainland will help pr...

The rock bass (Ambloplites rupestris) is a popular sport-fish native to the Mississippi and Great Lakes basins of North America. The species has been widely introduced outside its native range, including into Atlantic-slope streams of Virginia where it may hybridize with an imperiled, similar-looking congener, the Roanoke bass (Ambloplites cavifron...

Introduction The purpose of this chapter is to outline methods for standardized sampling of stream fishes in Panama. For the purposes of this document, we define "stream fishes" to mean any fish species (classes Petromyzontida, Chondrichthyes, Sarcopterygii, and Actinopterygii) that spends any portion of its life in freshwater streams that are shal...

Although groups of bats may be genetically distinguishable at large spatial scales, the effects of forest disturbances, particularly permanent land use conversions on fine-scale population structure and gene flow of summer aggregations of philopatric bat species are less clear. We genotyped and analyzed variation at 10 nuclear DNA microsatellite ma...

The purpose of this study was to continue annual monitoring of Roanoke logperch (Percina rex), an endangered fish, in the Smith River immediately upstream from Philpott Reservoir. This river reach is owned by the U.S. Army Corps of Engineers (USACE), which must ensure that appropriate actions are undertaken to aid in recovery of logperch. Monitorin...

Spatial variation in extinction and colonization is expected to influence community composition over time. In stream fish communities, local species richness (alpha diversity) and species turnover (beta diversity) are thought to be regulated by high extinction rates in headwater streams and high colonization rates in downstream areas. We evaluated...

Identifying and conserving functioning headwater ecosystems is essential for ensuring the structure and function of natural ecosystem processes. The Passage Creek watershed (PCW) in Virginia is an upland tributary system of the North Fork Shenandoah River, which is found within the Potomac River basin. The PCW appears to maintain an array of terres...

Ecological theory predicts that small dispersal rates can have large effects on population persistence and gene flow. Mark-recapture studies of individual stream fish typically conclude that movement is restricted to the reach scale (101-103 m). In contrast, less direct studies of dispersal (e.g., occupancy models, genetic studies) often find water...

The adaptive significance of inter-habitat movements by fishes generally is linked to seeking resources needed to complete life cycles; essential habitat-types include those facilitating survival, growth, and reproduction. Inter-habitat movement can satisfy a fish’s need to find complementary (distinct habitat-type) or supplementary (replicate habi...

Humans have altered the structural connectivity of rivers to an extent unrivaled in any other landscape type. A dramatic example is the upper Tennessee River basin (UTRB), which is bisected by 24 hydroelectric dams. While dams themselves likely are strong barriers to movement of riverine species, associated reservoirs and tailwaters may also impede...

Abstract –  Using mark–recapture methods, we studied movements of endangered Roanoke logperch (Percina rex Jordan & Evermann), a benthic darter, at 12 riffle–run sites over a 9-year-long period in the Roanoke River, Virginia, USA. Our primary objective was to characterise movements among transects within sites, but we opportunistically recorded two...

The Roanoke logperch (Percina rex Jordan and Evermann), an endangered fish, occurs in only six watersheds in the Roanoke and Chowan river drainages of Virginia, USA. The species' population genetic structure is poorly known. We developed 16 microsatellite markers that were reliably scorable and polymorphic P. rex. Markers were also screened in seve...

Although the efficacy and design of terrestrial movement corridors have received considerable attention, the potential role of corridors in connecting stream habitats has not. We studied the movements of three benthic species of fish, fantail darters Etheostoma flabellare, riverweed darters E. podostemone, and Roanoke darters Percina roanoka, among...

Relationships between environmental variability and movement are poorly understood, due to both their complexity and the limited ecological scope of most movement studies. We studied movements of fantail (Etheostoma flabellare), riverweed (E. podostemone), and Roanoke darters (Percina roanoka) through two stream systems during two summers. We then...

Externally visible injected marks provide valuable information to scientists, but their presence may increase an individual's susceptibility to predation. In a laboratory experiment, we evaluated the feeding preferences of rock bass (Ambloplites rupestris) and smallmouth bass (Micropterus dolomieu) for unmarked, green-VIE-marked, and yellow-VIE-mar...

Visible implant elastomer (VIE) and injectable photonic dye (IPD), two types of injectable fluorescent marks, have shown promise in previous applications in a variety of fishes but have not been extensively tested on darters. We marked a species from each of two genera of darters, Percina and Etheostoma, in a laboratory experiment to determine the...

Abstract – We examined the reproductive characteristics of 38 female longnose dace (Rhinichthys cataractae) from one of the southernmost populations of this species during two sampling periods in 1999 (ES=March 1999, LS=June 1999). Our data indicated that ES fish had not spawned, whereas LS fish had begun spawning. The smallest mature female captur...