News Article | May 22, 2017
Braving chest-deep water, boot-sucking mud and punishing heat in the cypress swamps of West Tennessee, biologists from the Tennessee Aquarium Conservation Institute and several partner organizations are trying to determine whether a dinosaur-like turtle could be on the downward slide to extinction. The Alligator Snapping Turtle is North America’s largest freshwater turtle species. In the mid-20th century, it was heavily harvested for its meat, and wild turtles are still being removed to supply the pet trade in the U.S. and Southeast Asia. After weathering decades of these parallel threats, no one is quite sure how many Alligator Snapping Turtles remain in Tennessee. Determining the population health of this shelled behemoth is a priority for the United States Fish and Wildlife Service, which is considering listing the Alligator Snapping Turtle under the Endangered Species Act. To determine whether this tri-ridged, fierce-beaked reptile warrants that designation, the service has enlisted the help of scientists to seek it out in its native swamps and rivers. In April 2016, Tennessee Aquarium Conservation Institute biologist Dr. Josh Ennen and representatives from the Tennessee Wildlife Resources Agency and Southern Missouri State University began a three-year research project to evaluate the distribution and population status of Alligator Snapping Turtles in West Tennessee. Using passive integrated transponder (PIT) tags, the researchers are able to uniquely identify any turtles they recover. By visiting the same locations over time and rescanning the turtles they capture, researchers will be able to estimate population numbers in a given area. Alligator Snapping Turtles have struggled against many threats, but fighting to survive is a position in which many turtles find themselves. About half of all turtles species are designated as some degree of vulnerable. “Turtles are one of the most-imperiled vertebrate groups,” Ennen explains. “They have the kind of life history that you can’t overexploit populations because they’re long-lived and slow to mature, so they can’t keep up with that kind of harvesting pressure.” As they conduct their population assessment, researchers also are gathering data to determine whether Alligator Snapping Turtles and other species with which they share their habitat are becoming unsafe for human consumption due to the build-up of mercury and other dangerous substances in their bodies. Particularly due to their longevity, turtles can serve as a kind of long-term litmus test for environmental conditions. By analyzing clippings of turtles’ claws, researchers can evaluate the concentration of toxic heavy metals in the surrounding habitat. If those levels are determined to be dangerously high, it could reflect a general downward trend in local water quality. Ironically, Ennen says, Alligator Snapping Turtles that survived being hunted or captured for the pet trade could be preserved thanks to environmental contamination that renders them unsafe to eat. “Those toxicity levels will serve as an indicator of what the water is like, both for other animals and for humans as well,” Ennen says. “Turtles can be bio-indicator species, so if there’s a contamination issue with turtles, you can have a contamination issue with fish and other animals.” Moving ahead, Ennen says, the hope is to seek an extension for the project to investigate rivers and swamps in Middle Tennessee and, in the near future, to begin using radio tracking to better understand the habitat use of juvenile Alligator Snapping Turtles in the study area. “We need to know where this species is found in the landscape and how it utilizes the habitat where it is found,” he says. “By extending our research of these long-lived animals, we’ll be able to develop a more complete picture of their numbers and individual health. That way, we’ll be better prepared to write a recovery plan if we determine these turtles should be listed as endangered.”
Jones J.,U.S. Fish and Wildlife Service |
Ahlstedt S.,U.S. Geological Survey |
Ostby B.,Virginia Polytechnic Institute and State University |
Beaty B.,Clinch Valley Program |
And 7 more authors.
Journal of the American Water Resources Association | Year: 2014
The Clinch River is located in northeastern Tennessee (TN) and southwestern Virginia (VA) of the United States, and contains a diverse mussel assemblage of 46 extant species, including 20 species listed as federally endangered. To facilitate quantitative monitoring of the fauna, quadrat data were collected from 2004 to 2009 at 18 sites in the river, including 12 sites in TN and 6 sites in VA. Thirty-eight mussel species were collected alive in total from quadrat samples taken annually at sites in the TN section of the river. Over the five-year study period, mussel density averaged 25.5 m-2 at all sites sampled in TN. In contrast, mussel density averaged only 3.1 m-2 at sites sampled in VA. The best historical site in VA was Pendleton Island in Scott County, where mussel density was estimated as high as 25 m-2 in 1979, comparable to current densities recorded in TN. Mussel densities are now <1 m-2, indicating a collapse of the fauna. A severe reduction in mussel abundance has occurred in a 68-km section of the river from St. Paul, VA, downstream to approximately Clinchport, VA (river kilometers 411.5-343.3). While the environmental factors responsible for the faunal decline are largely unknown, they must have been severe and sustained to reduce such large populations to their current low levels. Long-term water and habitat quality monitoring is needed to determine whether environmental degradation is still occurring in the river. © 2014 American Water Resources Association.
Murphy S.M.,University of Kentucky |
Cox J.J.,University of Kentucky |
Clark J.D.,University of Tennessee at Knoxville |
Augustine B.C.,Virginia Polytechnic Institute and State University |
And 3 more authors.
Journal of Wildlife Management | Year: 2015
Animal reintroductions are important tools of wildlife management to restore species to their historical range, and they can also create unique opportunities to study population dynamics and genetics from founder events. We used non-invasive hair sampling in a systematic, closed-population capture-mark-recapture (CMR) study design at the Big South Fork (BSF) area in Kentucky during 2010 and Tennessee during 2012 to estimate the demographic and genetic characteristics of the black bear (Ursus americanus) population that resulted from a reintroduced founding population of 18 bears in 1998. We estimated 38 (95% CI: 31-66) and 190 (95% CI: 170-219) bears on the Kentucky and Tennessee study areas, respectively. Based on the Tennessee abundance estimate alone, the mean annual growth rate was 18.3% (95% CI: 17.4-19.5%) from 1998 to 2012. We also compared the genetic characteristics of bears sampled during 2010-2012 to bears in the population during 2000-2002, 2-4 years following reintroduction, and to the source population. We found that the level of genetic diversity since reintroduction as indicated by expected heterozygosity (HE) remained relatively constant (HE(source, 2004) = 0.763, HE(BSF, 2000-2002) = 0.729, HE(BSF, 2010-2012) = 0.712) and the effective number of breeders (NB) remained low but had increased since reintroduction in the absence of sufficient immigration (NB(BSF, 2000-2002) = 12, NB(BSF, 2010-2012) = 35). This bear population appears to be genetically isolated, but contrary to our expectations, we did not find evidence of genetic diversity loss or other deleterious genetic effects typically observed from small founder groups. We attribute that to high initial genetic diversity in the founder group combined with overlapping generations and rapid population growth. Although the population remains relatively small, the reintroduction using a small founder group appears to be demographically and genetically sustainable. © 2015 The Wildlife Society.
News Article | November 3, 2016
For the Barrens Topminnow, conditions couldn’t get much worse. After months with little to no rain, the Middle Tennessee stream that serves as a vital habitat to one of the last remaining wild populations of endangered Barrens Topminnows has all but dried up. The once sparkling water has been reduced to a series of stagnant pools connected by an anemic trickle of murky water. After monitoring the ecological impact of the region’s exceptional drought for months, representatives from the Tennessee Aquarium Conservation Institute (TNACI) and U.S. Fish and Wildlife Service visited this critical stream on a farm north of Manchester, Tenn., to determine how bad conditions were and whether a rescue effort was warranted. As he looked out on the drought-ravaged scene, however, Tennessee Aquarium Aquatic Biologist Dr. Bernie Kuhajda realized the situation was even worse than anticipated. “I thought it’d be dry. I had no idea there’d be practically no water here,” Dr. Kuhajda said. “I don’t have a lot of hope. This was by far the healthiest population of Barrens Topminnows anywhere. This is pretty cataclysmic.” Despite its diminutive size and limited range, the Barrens Topminnow is part of a delicate ecosystem. Ensuring its survival is crucial to preserving the natural balance of the entire waterway, said Clay Raines, Tennessee Aquarium reintroduction biologist. “All we know for sure is that the more species you have, the more stable the ecosystem is,” he said. “You lose that chain, and no one can say, for certain, what those foundational species are — who’s most important and who’s least important — in that ecosystem. We have to value all aquatic life equally and preserve what we can.” The Middle Tennessee stream system, a tributary waterway of Lewis Creek, once contained hundreds of fish and served as habitat to a large percentage of the two remaining wild populations of Barrens Topminnows known to exist. As they sifted through the grubby catch of each seine net haul from the puddle-thin water, however, the team were finding found just a handful of Barrens Topminnows. Worse yet, they were disconcerted to discover plentiful Western Mosquitofish, a hardy invasive species which preys on Barrens Topminnow young. Mosquitofish had not been found in this tributary before. “The presence of Mosquitofish getting in these upstream headwater habitats is pretty disheartening,” said the Tennessee Aquarium’s Assistant Curator of Fishes Matt Hamilton, whose involvement in the Barrens Topminnow recovery program dates back to 1999. Once Mosquitofish begin to reproduce, he said, the demise of the Barrens Topminnows will become an almost foregone conclusion. “It’ll be a numbers game at that point,” he said. “Mosquitofish numbers are going to increase, and the Barrens Topminnows are going to decrease. These topminnows are a short-lived species, so it won’t be long until they are gone.” When environmental conditions become bad enough to place an entire species’ survival at risk, conservation scientists sometimes resort to bringing an entire wild population into human care to create an “ark population” to safeguard against the possibility of extinction. Within the Southeast, many such captive populations and propagation programs soon will be housed at TNACI’s flagship freshwater field station near downtown Chattanooga. This state-of-the-art facility on the banks of the Tennessee River opened on Oct. 27 and already serves as the headquarters for propagation programs for Southern Appalachian Brook Trout and Lake Sturgeon. After two and a half hours of work and dozens of seine hauls, the field team recovered just 64 Barrens Topminnows, an amount that previously could have been acquired in a single net drag. These individuals were placed in bags of clean, oxygenated water and taken to a TNACI facility as part of a new ark population. “Without taking this last-resort action, this population would be gone forever,” said Dr. Kuhajda. “Now there’s hope to keep this genetically distinct population intact with the long-term goal of re-establishing a healthy population here again.” The drought conditions are having a dramatic impact on many species throughout the Southeast’s extremely bio-diverse waterways. After witnessing the devastated conditions they found in Middle Tennessee, TNACI representatives will visit sites on Walden Ridge near Spring City, Tenn. This is one of the few remaining locations where the federally endangered Laurel Dace is found. If the streams conditions prove to be as bone-dry as the spring-fed waters in Middle Tennessee, whatever Laurel Dace remain will be rescued for another ark population. In the Cherokee National Forest, the ongoing exceptional drought and record-high temperatures have resulted in streams that are shallower, slower-flowing and warmer. These conditions are wreaking havoc on the native Southern Appalachian Brook Trout, whose habitat was already just 12 percent of its historical extent. Trout, which prefer cooler water, are concentrating in deeper pools. At lower elevations, their proximity to one another is leading to increased rates of disease and predation, said Jim Herrig, a forest aquatic biologist with the U.S. Forest Service Forest. “When we get to higher elevations, the larger streams are suffering really bad,” he said. “The water is getting so warm that the trout aren’t able to persist.” The Southern Appalachian Brook has been the subject of a long-term, collaborative restoration effort between TNACI, the U.S. Forest Service and the Tennessee Wildlife Resources Agency. Thanks to the reduced water flow, however, the facilities involved in this effort have been largely shuttered. “Nobody is going to be raising any Brook Trout this year,” Herrig said. The U.S. Fish and Wildlife Service has found a similarly deadly byproduct of the drought in a mass die-off of mussels in the Clinch River system of Northeast Tennessee and Southwest Virginia, where water levels are a fraction what they were in wetter months. “It’s definitely the driest we’ve ever seen it, and it’s been dry all around the state,” said Stephanie Chance, a USFWS listing and candidate conservation biologist, who assisted with the Barrens Topminnow recovery. “It’s troubling.” The work of conserving native species is complex and, in times like these, frustrating for biologists. Healthy populations of aquatic animals can deal with natural cycles that bring periods of drought, disease or other environmental stresses. But, when a species is already on the brink, the tipping point is easier to reach. Kuhajda believes shoring up these fragile ecosystems requires considering the important role fresh water plays in our daily lives and doing everything we can to safeguard it. “When our rivers and streams dry up, people really focus on water,” he said. “But we should be thinking about our most important resource throughout the year.” About Barrens Topminnows: Size: Up to 4 inches Range: Found only on the Barrens Plateau of Middle Tennessee Conservation Status: Endangered in Tennessee and currently under review for listing by the U.S. Fish and Wildlife Service. If approved, this species would be protected under the Endangered Species Act. Threats: The introduction of the Western Mosquitofish, which eats very young Barrens Topminnows, drought, water quality, and alteration of springs and small streams. Conservation Efforts: The Tennessee Aquarium monitors the Barrens Topminnow population and has worked with conservation partners to release more than 44,000 Barrens Topminnows into their natural habitat. Aquarium guests can see this ongoing work inside the Barrens Topminnow Lab Exhibit, which is located in the River Journey building.
Habera J.W.,Tennessee Wildlife Resources Agency |
Kulp M.A.,Great Smoky Mountains National Park |
Moore S.E.,Great Smoky Mountains National Park |
Henry T.B.,University of Plymouth |
Henry T.B.,University of Tennessee at Knoxville
North American Journal of Fisheries Management | Year: 2010
We evaluated three-pass depletion sampling for both AC and pulsed-DC electrofishing for estimating the population size of rainbow trout Oncorhynchus mykiss in a representative low-conductivity (20-μS/cm) southern Appalachian stream with limited habitat complexity. Trout capture efficiencies in such streams could be expected to exceed those observed in streams in which habitat is more complex; thus, depletion estimates could be much more accurate in the former. We also compared the results for two trout length-groups to investigate size-related differences. Measured capture efficiency was 0.88 ± 0.04 (95% confidence interval) for trout greater than 100 mm (typically adults) and 0.65 ± 0.09 for trout less than 100 mm (age 0). Population size was underestimated in each depletion sample. The errors for trout over 100 mm were generally small (mean, 12%; range, 3-23%), and the upper 95% confidence limits were usually within 10% of the true population size (N). Underestimates of N were larger for trout under 100 mm (mean, 32%; range, 5-60%), although the upper 95% confidence limits were within 20% of the N for half of the samples. The results of a laboratory study confirmed that trout over 100 mm were immobilized at significantly lower voltage gradients than were smaller trout in both electric fields. We conclude that three-pass depletion sampling is relatively accurate in typical southern Appalachian trout streams and that the underestimation errors for rainbow trout larger than 100 mm would be acceptable given basic inventory and monitoring goals. © American Fisheries Society 2010.
Vander Yacht A.L.,University of Tennessee at Knoxville |
Keyser P.D.,University of Tennessee at Knoxville |
Buehler D.A.,University of Tennessee at Knoxville |
Harper C.A.,University of Tennessee at Knoxville |
And 2 more authors.
Journal of Wildlife Management | Year: 2016
Oak (Quercus spp.) woodlands and savannas throughout the Mid-South, USA have become closed-canopy forests through succession in the absence of fire, contributing to declines in disturbance-dependent avian species. Restoration could ameliorate these trends, but effects of such management practices on avian communities of the Mid-South are poorly understood. We implemented an experiment on the Cumberland Plateau, Tennessee with treatments involving fall (Oct) or spring (Mar) fire with woodland (14 m2/ha) or savanna (7 m2/ha) residual basal area and unmanaged control stands (20 ha each). We conducted fixed-radius point counts 3 times annually (2010–2012) and analyzed trends in naïve occupancy for 41 species. For 20 species with adequate data (10 early-, 10 late-successional), we performed multiple-season, robust-design occupancy modeling and accounted for detection bias. We then used mixed-model polynomial regression to define relationships between occupancy and measures of live and dead basal area, midstory density, and herbaceous groundcover. Restoration substantially altered forest structural characteristics but did not affect the occupancy of most late-successional species. In contrast, the presence of early-successional species increased as live basal area decreased and herbaceous groundcover increased. Only 3 of 41 species (hooded warbler [Setophaga citrina], ovenbird [Seiurus aurocapilla], and worm-eating warbler [Helmitheros vermivorum]) exhibited reduced occupancy as woodland and savanna conditions were approached. The presence of all other species, including 13 regionally and 2 continentally declining, remained constant or increased as restoration progressed. Woodland conditions of 10 m2/ha live basal area and 20% herbaceous groundcover maximized occupancy of early-successional species with little consequences for late-successional species. Proceeding further toward savanna conditions negatively affected species associated with lower strata of mature-forests but further increased the presence of some early-successional species. Midstory density and dead basal area were poor predictors of occupancy and thus may be necessary but not sufficient in promoting early-successional species. Our results suggest implementing oak woodland and savanna management in the Mid-South could benefit disturbance-dependent birds of high conservation priority with minimal negative impacts on the presence of late-successional species. © 2016 The Wildlife Society. © The Wildlife Society, 2016
Bettoli P.W.,U.S. Geological Survey |
Scholten G.D.,Wallace State Office Building |
Hubbs D.W.,Tennessee Wildlife Resources Agency
North American Journal of Fisheries Management | Year: 2010
We developed an anchoring system for submersible ultrasonic receivers (SURs) that we placed on the bottom of the riverine reaches of three main-stem reservoirs in the upper Tennessee River. Each anchor consisted of a steel tube (8.9 × 35.6 cm) welded vertically to a round plate of steel (5.1×40.6 cm). All seven SURs and their 57-kg anchors were successfully deployed and retrieved three times over 547 d by a dive team employing surface air-breathing equipment and a davitequipped boat. All of the anchors and their SURs remained stationary over two consecutive winters on the hard-bottom, thalweg sites where they were deployed. The SUR and its anchor at the most downriver site experienced flows that exceeded 2,100 m3/s and mean water column velocities of about 0.9 m3/s. © by the American Fisheries Society 2010.
Blomquist S.M.,Tennessee Technological University |
Johnson T.D.,Tennessee Technological University |
Smith D.R.,U.S. Geological Survey |
Call G.P.,U.S. Fish and Wildlife Service |
And 5 more authors.
Journal of Fish and Wildlife Management | Year: 2010
We developed components of a decision structure that could be used in an adaptive management framework for responding to invasion of hemlock woolly adelgid Adeleges tsugae on the Cumberland Plateau of northern Tennessee. Hemlock woolly adelgid, an invasive forest pest, was first detected in this area in 2007. We used a structured decision-making process to identify and refine the management problem, objectives, and alternative management actions, and to assess consequences and tradeoffs among selected management alternatives. We identified four fundamental objectives: 1) conserve the aquatic and terrestrial riparian conservation targets, 2) protect and preserve hemlock, 3) develop and maintain adequate budget, and 4) address public concerns. We designed two prototype responses using an iterative process. By rapidly prototyping a first solution, insights were gained and shortcomings were identified, and some of these shortcomings were incorporated and corrected in the second prototype. We found that objectives were best met when management focused on early treatment of lightly to moderately infested but relatively healthy hemlock stands with biological control agent predator beetles and insect-killing fungi. Also, depending on the cost constraint, early treatment should be coupled with silvicultural management of moderately to severely infested and declining hemlock stands to accelerate conversion to nonhemlock mature forest cover. The two most valuable contributions of the structured decision-making process were 1) clarification and expansion of our objectives, and 2) application of tools to assess tradeoffs and predict consequences of alternative actions. Predicting consequences allowed us to evaluate the influence of uncertainty on the decision. For example, we found that the expected number of mature forest stands over 30 y would be increased by 4% by resolving the uncertainty regarding predator beetle effectiveness. The adaptive management framework requires further development including identifying and evaluating uncertainty, formalizing other competing predictive models, designing a monitoring program to update the predictive models, developing a process for re-evaluating the predictive models and incorporating new management technologies, and generating support for planning and implementation.
Twedt D.J.,U.S. Geological Survey |
Somershoe S.G.,U.S. Geological Survey |
Somershoe S.G.,Tennessee Wildlife Resources Agency |
Hazler K.R.,University of Georgia |
Cooper R.J.,University of Georgia
Journal of Wildlife Management | Year: 2010
Forest restoration has been undertaken on >200,000 ha of agricultural land in the Mississippi Alluvial Valley, USA, during the past few decades. Decisions on where and how to restore bottomland forests are complex and dependent upon landowner objectives, but for conservation of silvicolous (forest-dwelling) birds, ecologists have espoused restoration through planting a diverse mix of densely spaced seedlings that includes fast-growing species. Application of this planting strategy on agricultural tracts that are adjacent to extant forest or within landscapes that are predominately forested has been advocated to increase forest area and enhance forested landscapes, thereby benefiting area-sensitive, silvicolous birds. We measured support for these hypothesized benefits through assessments of densities of breeding birds and reproductive success of 9 species on 36 bottomland forest restoration sites. Densities of thamnic (shrubscrub dwelling) and silvicolous birds, such as yellow-breasted chat (Icteria virens), indigo bunting (Passerina cyanea), and white-eyed vireo (Vireo griseus) were positively associated with 1) taller trees, 2) greater stem densities, and 3) a greater proportion of forest within the landscape, whereas densities of birds associated with grasslands, such as dickcissel (Spiza americana) and red-winged blackbird (Agelaius phoeniceus), were negatively associated with these variables. Vegetation structure, habitat edge, and temporal effects had greater influence on nest success than did landscape effects. Taller trees, increased density of woody stems, greater vegetation density, and more forest within the landscape were often associated with greater nest success. Nest success of grassland birds was positively related to distance from forest edge but, for thamnic birds, success was greater near edges. Moreover, nest success and estimated fecundity of thamnic species suggested their populations are self-sustaining on forest restoration sites, whereas these sites are likely population sinks for grassland and open-woodland species. We recommend restoration strategies that promote rapid development of dense forest stands within largely forested landscapes to recruit breeding populations of thamnic and silvicolous birds that have reproductive success sufficient to sustain their populations. © The Wildlife Society.
Elkin K.,The Nature Conservancy |
Lanier S.,Tennessee Wildlife Resources Agency |
Rebecca M.,Richland Creek Watershed Alliance
Ecohydrology | Year: 2013
Fish Index of Biotic Integrity (IBI), macroinvertebrate North Carolina Biotic Integrity Index (NCBI) data, and Tennessee Macroinvertebrate Index (TMI) data were collected in 2009 and 2010 along with the hydrology to determine if a golf course water withdrawal was degrading the stream's aquatic life. Campostoma anomalum dominated the stream, and there were low numbers of Ephemeroptera-Plecoptera-Trichoptera (EPT) taxa. Richland Creek is a 28-square-mile watershed located in a highly urbanized area. The golf course withdraws a daily average of 400000(1514 cubic metre) gallons of water over a 60 to 155day period. McCabe Golf Course withdraws >10% of the flow in the low-flow months of June through October. Fish IBI scores were poor throughout Richland Creek with the upstream IBI being higher than downstream of the withdrawal. TMI scores were moderately impaired upstream and downstream of the golf course withdrawal, with the TMI being marginally better upstream of the withdrawal than downstream. The natural flow regime (Annear et al., 2004) is not maintained in Richland Creek because of the urban nature of the stream and the increased stormwater runoff into the stream. Tennessee Wildlife Resources Agency's instream flow policy statement states that flow should not be <20% above the September median flow, which is 12cfs (0·39 cms). The hydrology of the stream is altered by one major water withdrawal with its associated low-head dam as well as urbanization, which affects the fish and macroinvertebrate diversity. © 2012 John Wiley & Sons, Ltd.