Species Status Assessment Report for the Ashy Darter (Etheostoma Cinereum) Version 1.0

Species Status Assessment Report for the Ashy Darter (Etheostoma cinereum) Version 1.0

Photo Credit: Bernard Kuhajda, Tennessee Aquarium Conservation Institute

March 2018

Contents CHAPTER 1. INTRODUCTION ...... 1 CHAPTER 2. SPECIES NEEDS AND DISTRIBUTION ...... 3 Taxonomy ...... 3 Genetic Diversity ...... 3 Morphological Description ...... 3 Habitat ...... 5 Population Needs ...... 8 Species Needs ...... 8 Range and Distribution ...... 10 Historical Range...... 10 CHAPTER 3. FACTORS INFLUENCING VIABILITY ...... 13 Impoundments...... 13 Physical Habitat Disturbance ...... 14 Contaminants ...... 15 Sedimentation ...... 15 Reduced Range/Isolation ...... 16 Climate Change ...... 16 Conservation Actions ...... 17 CHAPTER 4. CURRENT MANAGEMENT UNIT CONDITION ...... 18 Population Elements ...... 18 Habitat Elements ...... 19 Current Population Status ...... 20 Upper Tennessee Management Unit ...... 21 Elk River Management Unit ...... 26 Duck River Management Unit ...... 27 Current Species Level Status ...... 29 Representation...... 29 Redundancy...... 30 CHAPTER 5: FUTURE SCENARIOS AND SPECIES VIABILITY ...... 31 Scenarios ...... 32 Scenario F ...... 32 Scenario W ...... 35 Scenario S ...... 38 i

Status Summary ...... 40 Future viability ...... 40 Uncertainty ...... 41 Overall Summary ...... 41 References ...... 43 Appendices ...... 50

CHAPTER 1. INTRODUCTION

The ashy darter (Etheostoma cinereum) is a fish in the family Percidae (Shepard and Burr 1984, p. 696) endemic (restricted to a locality or region) to the Tennessee River system. The ashy darter was designated a Category 2 Candidate species in 1994 (59 FR 58997), and remained such until that list was discontinued in 1996 (61 FR 64481). The ashy darter was petitioned to be listed under the Endangered Species Act of 1973, as amended (Act), as part of the Center for Biological Diversity’s 2010 Petition to List 404 Aquatic, Riparian and Wetland Species from the Southeastern United States (CBD 2010, p. 428-431).

In this report, we use the Species Status Assessment (SSA) framework (Smith et al. 2018, entire) to conduct an in-depth review of the species’ biology and threats, an evaluation of its biological status, and an assessment of the resources and conditions needed to maintain long-term viability. The intent is for the SSA Report to be updated as new information becomes available and to support all functions of the Endangered Species Program from Candidate Assessment to Listing, to Consultations and Recovery. As such, the SSA Report will be a living document upon which other decision documents would be based if the species warrants listing under the Act, including listing rules, recovery plans, and 5-year reviews.

This SSA Report for the ashy darter provides the biological support for the decision on whether or not to propose to list the species as threatened or endangered and, if so, where to propose designating critical habitat. Importantly, the SSA Report is not the decision by the Service on whether to propose the ashy darter for listing as a threatened or endangered species under the Act. Instead, this SSA Report provides a review of the available information strictly related to the biological status of the ashy darter. The listing decision will be made by the Service after reviewing this document and all relevant laws, regulations, and policies, and the results of a proposed decision will be announced in the Federal Register, with appropriate opportunities for public input.

For the purpose of this assessment, we generally define viability as the ability of the ashy darter to sustain natural populations in the Tennessee River system over time. Using the SSA framework (Figure 1.1), we consider what the species needs to maintain viability by characterizing the status of the species in terms of its resiliency, redundancy, and representation (Shaffer and Stein, 2000, entire; Wolf et al. 2015, entire).

● Resiliency describes the ability of populations to withstand stochastic events (arising from random factors). We can measure resiliency based on metrics of population health; for example, birth versus death rates and population size. Highly resilient populations are better able to withstand disturbances such as random fluctuations in birth

1 rates (demographic stochasticity), variations in rainfall (environmental stochasticity), or the effects of anthropogenic activities.

● Representation describes the ability of a species to adapt to changing environmental conditions. Representation can be measured by the breadth of genetic or environmental diversity within and among populations and gauges the probability that a species is capable of adapting to environmental changes. The more representation, or diversity, a species has, the more it is capable of adapting to changes (natural or human caused) in its environment. In the absence of species- specific genetic and ecological diversity information, we evaluate representation based on the extent and variability of habitat Figure 1.1 Species Status Assessment characteristics across the geographical range Framework and other factors as appropriate.

● Redundancy describes the ability of a species to withstand catastrophic events. Measured by the number of populations, their resilience, and their distribution (and connectivity), redundancy gauges the probability that the species has a margin of safety to withstand or can bounce back from catastrophic events (such as a rare destructive natural event or episode involving many populations).

To evaluate the biological status of the ashy darter, both currently and into the future, we assess a range of conditions to consider the species’ resilience, redundancy, and representation (together, the 3Rs). This SSA Report provides a thorough assessment of biology and natural history, and evaluates demographic risks, stressors, and limiting factors in the context of determining the viability and risks of extinction for the species. The format for this SSA Report includes (1) the resource needs of individuals and populations (Chapter 2); (2) the ashy darter’s historical distribution and a framework for determining the distribution of resilient populations across its range for species viability (Chapter 3); (3) the likely causes of the current and future status of the species and determining which of these risk factors affect the species’ viability and to what degree (Chapter 4); and (4) a description of viability in terms of resilience, redundancy, and representation (Chapter 5). This document is a compilation of the best available scientific and commercial information and a description of past, present, and likely future risk factors to the ashy darter.

CHAPTER 2. SPECIES NEEDS AND DISTRIBUTION

Biology and Life History Taxonomy In 1845, the ashy darter species was first described as Etheostoma cinereum by Storer (Shepard and Burr 1984, p. 693) based on specimens collected near Florence, Alabama. Bailey and Gosline (1955; in Shepard and Burr 1984, p. 693-4) placed the species in the monotypic subgenus Allohistium based on morphology (Family: Percidae).

Genetic Diversity In 2004 there were three distinct ashy darter management units recognized using the cytochrome b gene and morphological analyses Powers et al. (2004, entire): (1) Cumberland River (now recognized as redlips darter), (2) Duck River, and (3) upper Tennessee River drainages. Based on an analysis of meristic, morphometric, pigment, and genetic variation within and among populations of the ashy darter, the Cumberland River drainage management unit was described as a new taxon (Powers et al. 2012, entire), the redlips darter (Etheostoma maydeni). That same analysis indicated within species variation is such that ashy darter populations in the Duck, Elk, and upper Tennessee rivers are separate management units (Powers et al. 2012, p. 52).

Morphological Description

The ashy darter (Figure 1) is large relative to most other darter species, attaining a maximum total length of about 3.9 inches (in) (100 millimeters (mm)) (Shepard and Burr 1984, p. 696). It has thick papillose lips, with a long, pointy snout (Powers et al. 2012, p. 52; Shepard and Burr 1984, p. 696). On arches 1-3, the gill rakers are reduced, occurring in 7-9 discrete clusters. The breast and nape are unscaled and there are no palatine teeth. On the each side of the fish there is a mid-lateral row of 10-13 black rectangles that expand into diagonal bands of gray-brown. The bands are darker below the lateral line and form an interrupted lateral strip that extends through the eye and to the tip of the snout (Shepard and Burr 1984, p.696). There are usually four rows of orange dots on the upper sides of the darter.

Mature males have elongate and distally rounded second dorsal fins that nearly reach the caudal (tail) base when depressed. They have iridescent blue rays on anal and pelvic fins (Shepard and Burr 1984, p. 696). The ashy darter differs from the newly described redlips darter (E. maydeni), in that it does not have blood red on the lips, has 12 dorsal spines, 13 dorsal rays, and 25 caudal peduncle (area of body next to the tail fin) scales (Powers et al. 2012, p. 52).

Figure 2-1. Left lateral view of the ashy darter. (Photo Credit: Tennessee Aquarium Conservation Institute).

Figure 2-2. Ashy darter habitat: A, Elk River, Tennessee; B, Emory River, Tennessee (large boulder microhabitat). (Elk River photo by USFWS; Emory River photo curtesy of Tennessee Aquarium Conservation Institute.)

Habitat

Because the ashy darter was recently recognized as a species separate from the redlips darter, in 2012, the following information refers to observations that may be of either closely related species. However, species identity can be inferred if the basin (Cumberland or Tennessee) or year of observation (post 2012) is specified. The ashy darter occurs in medium-sized streams with silt free substrates (Shepard and Burr 1984, p. 708). These are typically clear, cool to warmwater streams with a moderate gradient (Jenkins and Burkhead 1993, p. 818). Collections have consistently occurred in the margins of pools with slow or moderate current above and below riffle habitat (Shepard and Burr 1984, p. 703). The ashy darter tends to occupy depths of 1.6 to 6.6 feet (ft) (0.5-2 meters (m)) in areas of bedrock or clean gravel substrate with rocks and boulders (Shepard and Burr 1984, p. 708). In the upper Tennessee River system, the ashy darter occupies backwater or pool habitats with slab rocks containing a slight layer of silt (Jenkins and Burkhead 1993, p. 818). The ashy darter has been found in close proximity to or underneath boulders (Etnier and Starnes 1993, p. 481) and in or near beds of water willow (Shepard and Burr 1984, p. 708).

A closely related species, the redlips darter, is associated with boulders, with adults found in pools and margins of run habitats with little or no flow (Compton and Taylor 2013, p. 188). Redlips darter adults were often associated with channel margins, while juveniles were distributed evenly across the channel and in area with gravel and pebble substrates (Compton and Taylor 203, p. 188-189). In the Cumberland River system, Comiskey and Etnier (1972, p. 143) occasionally found redlips darters in riffle habitats, but usually in pools approximately 3.3 ft (1 m) deep.

Feeding Habits

Midge (Chironomidae) larvae, burrowing mayfly larvae (Ephemera), and oligochaete worms are the primary prey items of the ashy darter complex; however, redlips darters showed a greater reliance on burrowing mayflies and oligochaetes (Shepard and Burr 1984, p. 711). Smaller individuals (< 1.6 in (40 mm) standard length (SL)) of both species fed almost exclusively on midges, while larger individuals (1.6-2.4 in (41-60 mm) SL) fed on a mixture of mayflies, oligochaetes, and midges (Shepard and Burr 1984, p. 711). Stomachs of the largest individuals (> 2.4 in (60 mm) SL) were dominated by larger food items such as mayflies, stoneflies (Plecoptera), and caddisflies (Trichoptera). Other reported food items included amphipods, isopods, mayflies (Stenonema), and limpets (Ferrissia) (Shepard and Burr 1984, p. 711; Powers and Mayden 2002, p. 264). The dominance of midge larvae, burrowing mayflies, and aquatic worms reinforce previous observations that the species’ principal habitat is sandy-bottomed pools where these prey items occur (Shepard and Burr 1984, p. 711). The species’ feeding behavior is unknown, but its elongated snout and papillose lips may be specializations for feeding on burrowing organisms.

Figure 2-3. Ashy darter lifecycle.

Lifecycle

Spawning likely occurs on the sides of boulders and on vegetation such as water willow stems (Etnier and Starnes 1993, p. 481) at a temperature of 48-68° Fahrenheit (F) (9-20° Celcius (C)) (Jenkins and Burkhead 1993, p. 818). The spawning season ranges from late January to mid- April (Etnier and Starnes 1993, p. 481; Shepard and Burr 1984, p. 711). Individuals from Little River, Tennessee, have been observed spawning in mid-February and early March (Jenkins and Burkhead 1993, p. 818). Based on laboratory observations of reproductive behavior, Rakes et al. (2015, p. 15-16) hypothesized that adults come into reproductive condition in the wild by early February and begin spawning when water temperatures exceed about 46°F (8°C). If water temperatures stay close to 50°F (10°C) or do not rise and stay above 59°F (15°C), spawning may last for one month or more.

Males and females become sexually mature by year 2 (all males > 2 in (50 mm) SL and females > 2.2 in (55 mm) SL) (Shepard and Burr 1984, p. 709), and females produce 50-250 ova (eggs) per year (Shepard and Burr 1984, p. 710). Spawning habitat and behavior in the wild are not completely understood, but the conical-shaped genital papilla of gravid females suggests the species may bury the eggs or attach them to hard substrates (Shepard and Burr 1984, p 711). In aquaria, both sexes participated in courting behavior with males tending to display slightly more courting activity until oviposition occurred, during which one egg was released per spawning act (Jenkins and Burkhead 1993, p. 818). Also in aquarium settings, females deposited eggs on filter tubes and pleated paper filters, which may have simulated water willow stems or roots, or rock crevices (Etnier and Starnes 1993, p. 481; Rakes et al. 2017, p. 5). Fertilization and deposition of eggs on the vertical side of a plastic box filter in an aquarium was observed (Jenkins and Burkhead 1993, p. 818) suggesting the sides of boulders may be spawning substrate in the wild.

Regarding the timing of spawning, eggs and larvae produced in the laboratory did not successfully develop at temperatures below 59°F (15°C) (optimal temperatures for spawning) (Rakes et al. 2017, p. 6). Based on these laboratory observations of spawning temperature, a successful hatch and recruitment may depend upon (1) the critical chance that occurrence and persistence of warmer temperatures overlap with the end of spawning or (2) the placement of eggs and the subsequent development of larvae in microhabitats that are warmer than the rest of the river, such as sun-warmed shallows. Attachment of eggs to water willow stems or other substrates in shallow, warmer marginal habitats would fit this scenario. In the Little River, Tennessee, upstream migration took place during the spring in preparation for spawning Greenberg (1991, p. 390).

The early life history of ashy darter is unknown, with the life stages of yolk-sac larvae and post yolk-sac larvae remaining undescribed (Simon and Wallus 2006, p. 160). In one study (Shepard and Burr 1984, pp. 709-710), 88 percent of males were sexually mature at age one, and 65 percent of one-year-old females were sexually mature. All fish were sexually mature at age two. Ashy darter total lengths of 1.6-3.0 in (40-75 mm) at age one, 2.0-3.0 in (50-94 mm) at age two, and 2.8-3.9 in (70-99 mm) at age three have been documented (Etnier and Starnes 1993, p. 481). The maximum size ranges from 3.3-3.9 in (83-100 mm) SL (Etnier and Starnes 1993, p. 481). No significant difference has been found in the growth rate of males versus females (Shepard and Burr 1984, p. 709). Ashy darter growth rates fastest in the Duck River system (Etnier and Starnes 1993, p. 481). Normal life span is three to four years (Etnier and Starnes 1993, p. 481), and the maximum is about 52 months (Shepard and Burr 1984, p. 708).

Life Stage Resources Needed Information Source Fertilized Egg Water temperatures > 59oF (15oC) (laboratory Rakes et al. 2017 setting); water willow stems/roots or rock crevices in shallow marginal habitats? Larva Water temperatures > 59oF (15oC) (laboratory Rakes et al. 2017 setting); water willow stems/roots or rock crevices in shallow marginal habitats? Juvenile Clear pools, runs, and glides of free-flowing Shepard and Burr 1984, medium to large upland streams and rivers; pp. 708-711; Etnier and cobble and boulder substrates throughout the Starnes 1993, p. 481; channel; stands of water willow, and woody Rakes et al. 2017, entire debris – with low amounts of siltation; food availability - Chironomidae (midge) larvae

Adult Clear pools, runs, and glides of free-flowing Shepard and Burr 1984, medium to large upland streams; large cobble pp. 708-711; Etnier and and slab-rock boulders (generally > 1.6 ft (0.5 Starnes 1993, p. 481; m)), especially along stream margins and with Powers and Mayden minimal embeddedness and siltation; food 2002, p. 264; Rakes et availability - burrowing mayflies, oligochaetes, al. 2017, entire midges, stoneflies, amphipods, isopods, and caddisflies.

Table 2-1. Overview of ashy darter individual needs.

Population Needs

Each population of the ashy darter needs to be able to withstand, or be resilient to, stochastic events or disturbances. Although they are infrequent, stochastic events are reasonably likely to occur and they can drastically alter the ecosystem where they happen. Classic examples of stochastic events include drought, major storms (hurricanes), fire, and landslides (Chapin et al. 2002, p. 285-288). To be resilient to stochastic events, populations of ashy darter need to have a large number of individuals (several hundred) (abundance), and occupy multiple sites in multiple subwatersheds (spatial extent). Additionally, populations need to exist in locations where environmental conditions provide suitable habitat and water quality such that adequate numbers of individuals can be supported. Without all of these factors, a population has an increased likelihood for localized extirpation.

Species Needs

For a species to persist and thrive over time, it must exhibit attributes across its range that relate to either representation or redundancy (Figure 2-4). Representation describes the ability of a species to adapt to changing environmental conditions over time and encompasses the “ecological and evolutionary patterns and processes that not only maintain but also generate species” (Shaffer and Stein 2000, p. 308). It is characterized by the breadth of genetic and

8 environmental diversity within and among populations. For the ashy darter to exhibit adequate representation, resilient populations should occur in the ecoregions and watersheds where it is native. These populations should occur at the widest extent possible across the historic range of the species and they should occupy multiple tributaries in drainages where they are native. Connectivity among populations maintains representation by facilitating genetic exchange

Redundancy describes the ability of a species to withstand catastrophic events. It “guards against irreplaceable loss of representation” (Redford et al. 2011, p. 42; Tear et al. 2005, p. 841) and minimizes the effect of localized extirpation on the range-wide persistence of a species (Shaffer and Stein, p. 308). Redundancy for the ashy darter is characterized by having multiple, resilient and representative populations distributed in each of the watersheds (e.g., Clinch, Elk, and Duck rivers) historically occupied by the species. For the ashy darter to exhibit redundancy, it must have multiple resilient populations with connectivity maintained among them because connectivity allows for immigration and emigration and increases the likelihood of recolonization should a population become extirpated.

Figure 2-4. How resiliency, representation, and redundancy are related to species viability.

Range and Distribution

Historical Range

In 1845, the ashy darter species was first described as Etheostoma cinereum by Storer (Shepard and Burr 1984, p. 696) based on specimens collected near Florence, Alabama. Whether this record is from the mainstem Tennessee River or a tributary is uncertain. Prior to large-scale impoundment, the historical range of the ashy darter encompassed the Tennessee River drainage, and probably included the mainstem Tennessee River (Etnier and Starnes 1993, p. 481). Historical records of the ashy darter are from the Clinch, Little, Emory, Elk, Duck, and Buffalo rivers; South Chickamauga Creek; and a limited number of tributaries to these rivers (Figure 2- 5). The species occurred in Lauderdale County, Alabama; Catoosa County, Georgia; Bedford, Blount, Hancock, Lawrence, Lewis, Lincoln, Maury, and Morgan counties in Tennessee; and Russell and Scott counties, Virginia.

Figure 2-5. All known ashy darter sites, current (2018 – 2008), historic (2007 – 1964), and extirpated (1962 – 1854).

Current Range

Currently, the ashy darter occupies Tennessee River tributaries in Bedford, Blount, Hancock, Lawrence, Lewis, Lincoln, Maury, and Morgan counties in Tennessee; and Scott and Russell counties, Virginia (Table 2-2). The ashy darter is considered extirpated in Alabama, near the time it was first described as a species in 1845, and in Georgia, where there is a single record from South Chickamauga Creek in 1953 (Etnier and Starnes 1993, p. 482; Alabama Wildlife Action Plan (ALWAP) 2015, entire; and Georgia Department of Natural Resources 2015, entire) and rare in Virginia (Jenkins and Burkhead 1993, p. 819). Moving east to west, the historical and current range includes the Ridge and Valley, Cumberland Plateau, Eastern Highland Rim, Nashville Basin, and Western Highland Rim physiographic provinces.

Location Date of Last Record Data Source Clinch River Guest River 2016 TVA Copper Creek 2015 TVA Clinch River, VA 2016 CFI Clinch River, TN 2015 TVA Little River Little River 2017 TVA Tellico River Little Tennessee River 1975 Shepard and Burr 1984 Tellico River* 2015 CFI reintroduction Emory River Emory River 2017 TVA South Chickamauga Creek South Chickamauga Creek 1953 Shepard and Burr 1984 Elk River Elk River, TN 2015 TVA Tennessee River or tributaries near Florence, AL Tennessee River 1845 Shepard and Burr 1984 Duck River Garrison Fork 2005 TVA Flat Creek 1999 TVA Duck River 2017 TVA Little Buffalo River 2008 TVA Buffalo River 2008 TVA

Table 2-2. All known ashy darter populations (in gray), with known tributaries and year of last collection. *Tellico River record indicates a reintroduction from Little River source stock.

CHAPTER 3. FACTORS INFLUENCING VIABILITY

Many factors influence ashy darter viability (Figure 3-1), including impoundment, chemical spills, coal mining, and siltation (Shepard and Burr 1984, p. 702).

Figure 3-1. Stressor influence diagram for the ashy darter.

Impoundments

Impoundments cause dramatic modification of riffle and shoal habitats and the resulting loss of fish resources, especially in larger rivers. Dams interrupt most of a river’s ecological processes by modifying flood pulses; controlling impounded water elevations; altering water flow, sediments, nutrients, energy inputs, and outputs; increasing depth; decreasing habitat heterogeneity; and decreasing bottom stability due to subsequent sedimentation. In addition, dams can seriously alter downstream water quality and riverine habitat and negatively impact tailwater fish populations. These changes include thermal alterations immediately below dams; changes in channel characteristics, habitat availability, and flow regime; daily discharge fluctuations; and increased silt loads. Coldwater releases from large, non-navigational dams and scouring of the river bed from highly fluctuating, turbulent tailwater flows have also been implicated in the demise of fish faunas (Layzer and Scott 2006, entire). 13

There are several large reservoirs in the Tennessee River system (Table 3-1). By 1971, approximately 3,700 river kilometers (rkm) (2,300 river miles (rmi)) of the Tennessee River and its tributaries with drainage areas of 65 square km (25 square mi) or greater were impounded by the TVA (TVA 1971, p. 5). In total, the length of this impounded area encompassed 20% of the Tennessee River system in 1971. The subsequent completion of additional major impoundments on tributary streams (e.g., Duck River in 1976, Little Tennessee River in 1979) significantly increased the total river kilometers impounded behind the 36 major dams in the Tennessee River system. There are many smaller impoundments in the range of the ashy darter that affect habitat and connectivity. For example, there are at least 25 mill dams on the Duck River (Ahlstedt et al. 2004, p. 6 [citing LaForest and Oliveira 1979]).

Reservoir Closure Date River Impounded Length (rmi/rkm) Affected Ashy Darter Habitats Norris 1936 Clinch and Powell 73 (117.5) Clinch River 56 (90) Fort Loudon 1943 Tennessee River 49.9 (80.3) Tennessee and Little rivers Tellico 1979 Little Tennessee 33 (53) Little Tennessee River and Tellico rivers Melton Hill 1963 Clinch River 44 (70.8) Clinch River Watts Bar 1942 Tennessee and 72.4 (116.5) Tennessee, Clinch, Clinch 23.1 (37.2) and Emory rivers Chickamauga 1940 Tennessee 58.9 (94.5) Tennessee River Nickajack 1967 Tennessee 46.3 (74.5) Tennessee River Guntersville 1939 Tennessee 75.7 (121.8) Tennessee River Wheeler 1936 Tennessee 74.1 (119.3) Tennessee and Elk rivers Wilson 1924 Tennessee 15.5 (24.9) Tennessee River Pickwick Landing 1935 Tennessee 52.7 (84.8) Tennessee River Kentucky 1944 Tennessee 184.3 (296.6) Tennessee, Duck, and Buffalo rivers

Table 3-1. Major reservoirs impounding the Tennessee River and tributaries.

Physical Habitat Disturbance

Common types of stream habitat modification include channelization, loss of riparian habitat (through tree cutting, mowing, or livestock grazing along stream banks), changes in land use that affect flow regimes, dams, and gravel mining (Tennessee Department of Environment and Conservation (TDEC) 2014, p. 48). Channelization is typically conducted for drainage improvements, and is any combination of widening, straightening, and deepening of streams, and often includes removal of riparian vegetation (Brooker 1985, p. 63). The reduction or loss of riparian vegetation results in the elevation of stream temperatures, destabilization of stream banks and resulting siltation, and removal of submerged root systems that provide habitat for fish and macroinvertebrates (Minshall and Rugenski 2006, pp. 721–723). Other channelization

effects include accelerated erosion, decreased habitat diversity, channel instability, and riparian canopy loss (Hartfield 1993, p. 131; Hubbard et al. 1993, pp. 136–145). Following channelization of a Tennessee stream there was a decline in fish diversity and abundance, and macroinvertebrate richness, and an increase in substrate instability and habitat homogeneity (Etnier 1972, pp. 373–375).

In Tennessee, 5,686 km (3,533 mi) of streams are impaired because of channelization, 4,865 km (3,023 mi) are impaired due to riparian habitat removal, and 10,029 km (6,232 mi) are impaired due to grazing in riparian areas (TDEC 2014, p. 63-4). In parts of the Tennessee River watershed, such as the Little River, where the ashy darter occurs, rapid commercial and residential development is leading to increased areas of impervious surfaces (TDEC 2014, p. 62).

Contaminants

Sources of water quality impairment in the Tennessee River Basin in Virginia include unrestricted cattle access, rural residential areas, unknown sources, coal mining, sewage discharges in unsewered areas, and surface mining (VADEQ 2017, p. 83). Except for coal mining, these sources of impairment are the same in the Tennessee portion of the Basin. Activities associated with surface coal mining (e.g., land clearing, road construction, excavation) produce large areas of bare soil that, if not protected or controlled through various erosion control practices, can contribute large amounts of sediment into streams during storm events. Land use practices such as the placement of valley fills for mining or road construction can affect sediment and water discharges into downstream stream reaches, leading to increased erosion or sedimentation patterns, destruction or modification of in-stream habitat and riparian vegetation, stream bank collapse, and increased water turbidity and temperature (Wiley et al. 2001, pp. 1– 16; Messinger 2003, pp. 17–20). Increased levels of ammonia, metals, and dissolved solids have been observed in the Guest River, a tributary to the Clinch River in Virginia where a significant portion of the surrounding land use is active, reclaimed, and abandoned coal mining (Price et al. 2014). Total dissolved solids concentrations have continued to rise in the mainstem Clinch River as well (Price 2011).

Sedimentation

Excess sediment can bury instream habitats used by fishes for foraging, reproduction, and sheltering, and can disrupt the dynamic equilibrium of channel width, depth, flow velocity, discharge, channel slope, roughness, sediment load, and sediment size that maintains stable channel morphology (Allan 2004, p. 262). Loss of stream-side vegetation promotes bank erosion that alters stream courses and introduces large quantities of sediment into the channel. This can lead to channel instability and further degradation of instream habitats. Excessive suspended and deposited sediment has been shown to damage and suffocate fish gills and eggs, larval fishes, bottom dwelling algae, and other organisms; reduce aquatic insect diversity and abundance; and, ultimately, negatively affect fish growth, survival, and reproduction (Berkman and Rabeni 1987, pp. 285–294; Waters 1995, pp. 5–7; Wood and Armitage 1997, pp. 211–212; Meyer and Sutherland 2005, pp. 2–3). In addition to the aforementioned land uses that are sources of contaminants, logging activities without sufficient erosion and sedimentation controls can affect ashy darters by increasing instream sediment loads.

Reduced Range/Isolation

The ashy darter has a limited geographic range and the size of its populations is unknown. Existing populations are localized, and geographically isolated from one another, leaving them vulnerable to extirpation from intentional or accidental toxic chemical spills, habitat modification, progressive degradation from runoff (non-point source pollutants), environmental stochasticity, and decreased fitness from reduced genetic diversity. Potential sources of unintentional spills include accidents involving vehicles transporting chemicals over road crossings of streams inhabited by the ashy darter, or the accidental or intentional release of chemicals used in agricultural or residential applications into streams.

Species that are restricted in range and population size are more likely to suffer loss of genetic diversity due to genetic drift, potentially increasing their susceptibility to inbreeding depression, decreasing their ability to adapt to environmental changes, and reducing the fitness of individuals (Soulé 1980, pp. 157–158; Hunter 2002, pp. 97–101; Allendorf and Luikart 2007, pp. 117–146). Although the genetic diversity of ashy darter populations remains mostly unstudied, it is possible that some ashy darter populations are below the effective population size required to maintain long-term genetic and population viability (Soulé 1980, pp. 162–164; Hunter 2002, pp. 105– 107). The long-term viability of a species depends on the conservation of numerous local populations throughout its geographic range (Harris 1984, pp. 93–104). These separate populations are essential for the species to recover and adapt to environmental change (Harris 1984, pp. 93–104; Noss and Cooperrider 1994, pp. 264–297). The current level of isolation in ashy darter populations, owing primarily to large impoundments, makes natural repopulation following extirpations virtually impossible without human intervention in certain parts of the range. However, we have no evidence that restricted range and population size are causing ongoing declines in ashy darter populations. The species’ relatively broad distribution and high number of occupied streams increases its resiliency (capacity of a species to withstand stochastic events) and redundancy (capacity of a species to withstand catastrophic events).

Climate Change

The Intergovernmental Panel on Climate Change (IPCC) concluded that warming of the climate system is unequivocal (IPCC 2014, p. 3). Numerous long-term climate changes have been observed, including changes in arctic temperatures and ice, widespread changes in precipitation amounts, ocean salinity, wind patterns and aspects of extreme weather including droughts, heavy precipitation, heat waves, and the intensity of tropical cyclones (IPCC 2014, p. 4). Species that are dependent on specialized habitat types, limited in distribution, or at the extreme periphery of their range may be most susceptible to the impacts of climate change (75 FR 2010, p. 48911); however, while continued change is certain, the magnitude and rate of change is unknown in many cases. Climate change has the potential to increase the vulnerability of the ashy darter to random catastrophic events (McLaughlin et al. 2002, pp. 6060-6074). An increase in both severity and variation in climate patterns is expected, with extreme floods, strong storms, and droughts becoming more common (Cook et al. 2004, pp. 1015-1018; Ford et al. 2011, p. 2065; IPCC 2014, pp. 58-83). Thomas et al. (2004, pp. 145-148) report that frequency, duration, and

intensity of droughts are likely to increase in the Southeast as a result of global climate change. Predicted impacts of climate change on fishes include disruption to their physiology (such as temperature tolerance, dissolved oxygen needs, and metabolic rates), life history (such as timing of reproduction, growth rate), and distribution (Jackson and Mandrak 2002, pp. 89-98; Heino et al. 2009, pp. 41-51; Strayer and Dudgeon 2010, pp. 350-351; Comte et al. 2013, pp. 627-636). According to Kaushal et al. (2010, p. 465), stream temperatures in the Southeast have increased roughly 0.4-0.7oF (0.2-0.4oC) per decade over the past 30 years, and as air temperature is a strong predictor of water temperature, stream temperatures are expected to continue to rise.

Conservation Actions

From 2011-2016, Conservation Fisheries, Inc. (CFI) monitored and collected ashy darters from the Little River with the intent of captive propagation and reintroduction into the Tellico River. From 2012 to 2016, ashy darters were reintroduced into the Tellico River from Little River source stock (Rakes et al. 2017, p. 12).

There are no public lands adjacent to ashy darter occupied habitat. However, the Emory River watershed contains the Catoosa Wildlife Management Area (WMA) and The Nature Conservancy (TNC) owns lands in the Clinch River watershed. The Virginia Department of Conservation and Recreation (VADCR) and TNC are working to develop a Clinch River State Park on the Virginia side of the Clinch River, which would consist of a series of riverside properties. Funds have been secured and lands are being acquired from willing sellers/donors.

The Service along with TNC, local Soil and Water Conservation Districts, the Natural Resources Conservation Service, Farm Service Agency, Clinch-Powell Resource Conservation and Development Council, and many State agencies and local partners are working together to protect aquatic biodiversity in the Clinch River watershed by providing monetary and technical assistance to facilitate the protection and recovery of riparian corridors and the reduction and prevention of non-point source pollution on private lands. Similarly, through their Landowner Incentive Program, TNC has provided monetary and technical assistance to facilitate protection of riparian corridors along the Duck River to prevent non-point pollution from private lands.

There are numerous federally listed species and there is federally designated critical habitat for freshwater mussels throughout the range of the ashy darter (i.e., Clinch, Elk, Duck, Buffalo rivers) (Appendix 1, 2). The Virginia Department of Game and Inland Fisheries (VDGIF) considers the ashy darter a Tier 1 species, and have developed research needs for the darter (VDGIF 2015, entire). The ashy darter is listed as threatened by the State of Tennessee, and is a Tier 1 species in the Tennessee Statewide Wildlife Action Plan (TNSWAP 2015, entire).

In 2017, a range-wide status survey was conducted (TNACI 2017, unpublished data). While there is not a monitoring program specifically for the ashy darter, the Tennessee Valley Authority (TVA), TNACI, CFI, and Tennessee Wildlife Resources Agency (TWRA) collect the darter in routine fish surveys.

CHAPTER 4. CURRENT MANAGEMENT UNIT CONDITION

Current habitat and population conditions within each management unit are described below. This section details specific stressors acting within the occupied range of the species. Additionally, collection history and extent of occurrence data for populations within the management units are provided. Current population resilience is assessed for each location and population specifically, followed by a summary of range-wide redundancy and representation.

To assess current viability we considered six components that broadly relate to either characteristics about the population specifically (“Population Elements”) or the physical environment (“Habitat Elements”). Habitat elements consisted of an evaluation of physical habitat, connectivity, and water quality. Population elements consisted of occurrence (species recently detected), occurrence extent, and occurrence complexity. We further defined how each of these components might vary in terms of condition (see Table 4-1).

There are no population genetic or movement data to indicate whether ashy darters in each tributary system function as a single population or multiple populations. Therefore, for or our analysis, we divided the species’ range into “populations” as separated by major impoundments on the Tennessee River, because there is no connectivity between these populations.

Population Elements

To evaluate the population elements, we used Heritage database records, results of a recent (2017-2018) range-wide survey for ashy darter conducted by TNACI (TNACI 2018, entire), and collections conducted since 2017 by the TVA (TVA 2017, unpublished data).

Sampling methods varied among collections, and because not all sampling specifically targeted the ashy darter, we did not analyze abundance. Instead, we documented the presence or absence (occupancy) of ashy darters observed in each tributary system during recent surveys (since 2008). A tributary system was considered to be extirpated if no individuals were observed since 1962 (despite surveys) and general habitat conditions were considered unsuitable for the species. We considered current occupancy condition to be high if the ashy darter was observed in collections since 2008 and unsuitable if there were no records since 2008.

Occurrence extent for the ashy darter was evaluated by measuring the distance between the most upstream record and the most downstream record. When applicable (e.g., Little and Buffalo rivers) historical and current records were assessed separately to determine and quantify any range reduction that may have occurred. To determine the current range, we used all records obtained between 2008 and 2018 and evaluated how those records compared to historical collections. Currently, the ashy darter occupies approximately 80% of its historically known range using the method described above.

Occurrence complexity is a measure of the spatial complexity of the occupied habitat. For aquatic species that inhabit large streams or rivers, complex spatial occurrence relates to a species occupying multiple tributaries and the river mainstem as opposed to only inhabiting the river mainstem. If connectivity is sufficient, then a more complex and dendritic (tree-like) spatial

arrangement of occupied habitat will be more resilient against extinction (Fagan 2002, p. 3244). We considered high occurrence complexity to exist when individuals occupied the river mainstem in addition to at least two major tributaries. Low occurrence complexity would exist if a species only inhabited a short reach of the river mainstem.

Habitat Elements

The quality of physical habitat was evaluated by determining how well it suited the needs of the ashy darter. We considered any habitat stressors, such as disturbance from activities associated with agriculture, resource extraction, or development.

Connectivity was determined based on of fish passage barriers within the population. The ability for species to move upstream and downstream is important for feeding, spawning migration, seasonal movements, and refuge from extreme high or low water events, as well as the exchange of genetic material.

We evaluated water quality by determining how many impacts were identified, their severity, and if measures have been taken toward removing the issues. State Clean Water Act Section 303(d) reports and other water quality reports were used to identify impacted water quality and mitigation measures if they applied.

Quality High Medium Low Unsuitable Physical Habitat No known Known low level Habitat heavily Unable to support alteration alterations to altered and survival habitat recognized as impacting species Connectivity No known Passage barriers Passage barriers Unable to support barriers to fish known but do not identified as survival passage impact species negatively impacting populations Water Quality Minimal or no Issues recognized WQ issues known Unable to support known water (e.g., 303d to impact survival quality issues streams) populations Present in None observed Occupancy Collections since N/A N/A 2008-Present 2008 Occurrence Entire known <30% decline >30% decline in Extirpated Extent range currently from known range known range occupied Occurrence Occupies main Occupies main Occupies main Extirpated Complexity channel and channel and one channel multiple tributary tributaries Table 4-1. Definitions of conditions for components used to assess current condition.

Current Population Status

For the ashy darter to exhibit high representation, its populations should exhibit high resiliency and should occur in all physiographic provinces where they are native. These occupied populations should occur at the widest extent possible across the historical range of the species and they should occupy at least one tributary in addition to the core population within the mainstem of a river in the Upper Tennessee, Elk River, and Duck River management units. Within each population there should be multiple viable, occupied sites to reduce the chance of extirpation. Finally, connectivity should be maintained between representative populations because it allows for the exchange of novel and beneficial adaptations. Where connectivity is naturally lower and the species is more isolated, this isolation can serve as a mechanism for localized adaption and variation.

High redundancy for the ashy darter is characterized by having multiple resilient and representative populations distributed within the species’ ecological setting and across its range. For this species to exhibit high redundancy it must have highly resilient populations with connectivity maintained among them. Connectivity allows for immigration and emigration between populations and increases the likelihood of recolonization should a population become extirpated. Additionally, populations should have a low likelihood of extirpation due to catastrophic events.

Upper Tennessee Management Unit

Clinch River Population

The ashy darter occupies 121 rmi (195 rkm) in the Clinch River, Tennessee and Virginia, and the mouths of Guest River and Copper Creek (Figure 4-1). There has been no loss of historical known occupancy and there has been an expansion of the species’ range in the river (TNACI 2018, p. 3). After a chemical spill in 1967, the species was assumed extirpated from the Clinch River in Virginia. However, the species was rediscovered in Virginia in 2004 (Rakes and Shute 2008, p. 2).

Chemical spills and inundation by Norris Lake were important factors that contributed to the species’ decline within the Clinch River system historically (Shepard and Burr 1984, p. 702). Portions of the Clinch River, Copper Creek, and the Guest River are 303d listed in Virginia (VADEQ 2017, pp. Appendix I-65, 69, 70-72). Sources of water quality impairment in the Tennessee River Basin in Virginia include unrestricted cattle access, rural residential areas, unknown sources, coal mining, sewage discharges in unsewered areas, and surface mining (VADEQ 2017, p. 83). Except for coal mining, the land use in the Tennessee portion of the Clinch River is the same as in Virginia.

Other than Norris Lake, which isolates the Clinch River watershed from the rest of the Upper Tennessee River system, no significant fish passage barriers are known. Therefore, in the Clinch River, connectivity does not appear to be a hindrance to seasonal movements, refuge from extreme high or low water events, feeding behavior, or the exchange of genetic material.

The Clinch River population continues to occupy the entirety of its historically known range in the mainstem, as well as the lowest ends of the Guest River and Copper Creek. Due to low impacts to habitat and population elements, the Clinch River population has a high resilience to stochastic events (Table 4-2).

Figure 4-1. Clinch River population of the ashy darter.

Little River Population

The ashy darter occupies approximately 12 rmi (19 rkm) in the Little River, Tennessee (Figure 4- 2). This represents a 5 rmi (8 km) loss of historically occupied habitat. The species was collected between 2011 and 2013 at two sites by CFI and again in 2017 by TVA and TNACI (Petty et al. 2013, p. 16; TNACI 2018, p. 4; TVA 2017, unpublished data).

Connectivity and ashy darter passage is limited within Little River, with Perry’s Mill Dam preventing upstream range expansion. The Fort Loudon Lake impoundment at the mouth of Little River prevents movement into the Tennessee River and contact with other populations in its tributaries.

The Little River population continues to occupy 58% of its historically known range. Due to moderate impacts to both habitat and population elements, the Little River population has a medium resilience to stochastic events (Table 4-2).

Figure 4-2. Little River population of the ashy darter.

Tellico River Population

The ashy darter has not been observed in the Little Tennessee River since 1975, in a reach of the river now impounded by Tellico Lake (Figure 4-3). In 2012, 25 ashy darters were first introduced into the Tellico River, a Little Tennessee River tributary, from Little River source stock. In 2015, 107 ashy darters were introduced into one site in the Tellico River by CFI, followed by 57 in 2016 (Rakes et al. 2015, p.15-19; Rakes et al. 2017, p. 12). The introduction sites were chosen based on the availability of habitat in the probable historical range, in close proximity to the Little River population (Rakes et al. 2015, p. 12). Although one individual was seen a few months after reintroduction, introductions will need to proceed for several years before this population can become fully established (Rakes et al. 2015, p. 15).

The Little Tennessee River is a 303d listed stream due to upstream impoundment (TDEC 2016, p. 94). No significant fish passage barriers are known from the Tellico system, so connectivity does not appear to be an issue with respect to seasonal movements, refuge from extreme high or low water events, feeding behavior, or the exchange of genetic material.

The Tellico River population has been recently established through stocking efforts. It is too early to tell if stocking will be successful. Due to moderate impacts to both habitat and population elements, as well as population augmentation efforts, the Tellico River population has a medium resilience to stochastic events (Table 4-2).

Figure 4-3. Tellico River population of the ashy darter.

Emory River Population

The ashy darter occupies 8 rmi (13 rkm) in the Emory River, Tennessee (Figure 4-4). This represents a loss of 3 rmi (5 rkm) of historically known occupied habitat. In 2017 there were multiple collections of ashy darters, with one darter found per collection (TNACI 2017, unpublished data; TVA 2017, unpublished data).

Coal mining, pollution, and inundation by Watts Bar Lake were identified as factors modifying ashy darter habitat in the Emory River (Shepard and Burr 1984, p. 702). Emory River is a 303d listed stream due to atmospheric mercury contamination (TDEC 2016, p. 103).

No significant fish passage barriers are known in the Emory River, but it is isolated from the rest of the Tennessee River system by Watts Bar Lake at its mouth. Therefore, within the Emory River connectivity does not appear to be an issue with respect to seasonal movements, refuge from extreme high or low water events, feeding behavior, or the exchange of genetic material.

The Emory River population continues to occupy 62% of its historically known range. Due to moderate impacts to both habitat and population elements, the Emory River population has a medium resilience to stochastic events (Table 4-2).

Figure 4-4. Emory River population of the ashy darter.

South Chickamauga Creek Population There is one record of ashy darter from South Chickamauga Creek, Georgia, from 1953, which is the only observation of the species in the state. Siltation and industrial and domestic pollution have been identified as important factors in the species’ decline within the South Chickamauga Creek system (Shepard and Burr 1984, p. 702). The South Chickamauga Creek population is extirpated.

Elk River Management Unit

Elk River Population

The ashy darter occupies 29 rmi (47 rkm) in the Elk River, Tennessee (Figure 4-5). This represents a loss of two rmi (three rkm) of historically known occupied habitat. From 1981 to 2015, single individuals have been sporadically collected in TVA fish samples (TVA 2017, unpublished data).

The Elk River is a 303d listed stream due to pasture grazing and upstream impoundment (TDEC 2016, p. 130-134). The Elk River has at least one known barrier, Harms Mill Dam, so connectivity is hampered with respect to seasonal movements, refuge from extreme high or low water events, feeding behavior, and the exchange of genetic material. The Elk River population continues to occupy 93% of its historically known range. Due to moderate impacts to both habitat and population elements, the Elk River population has a medium resilience to stochastic events (Table 4-2).

Figure 4-5. Elk River population of the ashy darter.

Tennessee River (or Tributaries) Population

In 1845, the ashy darter species was first described based on specimens collected near Florence, Alabama (Figure 2-5) (Shepard and Burr 1984). The species is considered extirpated from Alabama and there are no subsequent records from the mainstem Tennessee River or its tributaries near Florence. Siltation, isolation, and inundation by Pickwick Landing, Wilson, and Wheeler lakes have been identified as important factors in the species’ decline within the system (Shepard and Burr 1984, p. 702). The Tennessee River (or tributaries) population is extirpated.

Duck River Management Unit

Duck River Population

The ashy darter occupies 113 rmi (182 rkm), 66 percent of historically occupied habitat, in the Duck River system, Tennessee (Figure 4-6). This represents a loss of 9 rmi (14 rkm) of historically known occupied habitat in the mainstem Duck River. Recent collections (2008-2017) found between one and six individuals, with as many as 30 collected at a site in 2011, some of the highest abundance observations ever recorded for the species (TNACI 2017, unpublished data; TVA 2017, unpublished data). There are no current records in the historically occupied mouths of Flat Creek and Garrison Fork, although there are no recent surveys specifically for the ashy darter in these Duck River tributaries.

The ashy darter occupies 3 rmi (5 rkm) in the Buffalo River system (major Duck River tributary), in Little Buffalo Creek and the mouth of Grinder’s Creek. The ashy darter was historically known from a 55 rmi (89 rkm) reach of the Buffalo River; this represents a loss of 52 rmi (84 km) of historically known occupied habitat. The only current record, from 2008, is from the mouth of Grinder’s Creek where a single individual was found (TVA 2017, unpublished data). In 2008, two individuals were found at one site (two separate occasions) in Little Buffalo Creek (TVA 2017, unpublished data). The ashy darter has been lost from 95% of its known historical range in the mainstem Buffalo River. It is not known whether the decline in range is due to the difficulty in detecting ashy darters when present or is a true indicator of local extirpations.

Inundation by Normandy Lake was identified as a factor modifying ashy darter habitat in the Duck River (Shepard and Burr 1984, p. 702). Fountain Creek is a 303d listed stream due to unrestricted cattle access (TDEC 2016, p. 139). Other portions of the Duck River are 303d listed due to stormwater discharge, upstream impoundment, collection system failure, atmospheric deposition of mercury, pasture grazing, municipal point source pollution, and phosphorus mining (TDEC 2016, p. 140-146). Portions of the Buffalo River are 303d listed due to atmospheric deposition of mercury (TDEC 2016, p. 148). Despite the historical impacts incurred by the Duck River, water quality and freshwater mussel populations, which are sensitive to pollutants, have improved dramatically since the late 1980s (Ehlo and Layzer 2014, pp. 3, 12)

There are several low-head dams and one large flood control dam on the Duck River that reduce connectivity, which hampers seasonal movements, refuge from extreme high or low water events, feeding behavior, and the exchange of genetic material.

The Duck River population continues to occupy 66% of its known historical range in the mainstem Duck and Buffalo rivers and in one additional tributary. Due its high water quality, physical habitat, and occurrence complexity (habitat and population elements) the Duck River population has a high resilience to stochastic events (Table 4-2).

Figure 4-6. Duck River population of the ashy darter.

Physical Connectivity Water Quality Occupancy Occurrence Occurrence Current Habitat Extent Complexity Condition Clinch River High High Medium High High High High Little River Medium Medium Medium High Low Low Medium Tellico River* Medium High High High Low Low Medium Emory River High High Medium High Low Low Medium South Chickamauga Low Low Low Extirpated Extirpated Extirpated Extirpated Creek Elk River Medium Medium Medium High Medium Low Medium Tennessee River Low Low Low Extirpated Extirpated Extirpated Extirpated tributaries at Florence, AL Duck River High Medium High High Medium High High Table 4-2. Current resilience of ashy darter populations (*indicates a stocked site/reintroduction effort).

Current Species Level Status

Representation

Representation describes the ability of a species to adapt to changing environmental conditions over time and encompasses the “ecological and evolutionary patterns and processes that not only maintain but also generate species” (Shaffer and Stein 2000, p. 308). We estimate that the ashy darter has a medium adaptive potential. The ashy darter has multiple populations occurring over a wide extent across the Tennessee River watershed, in the Upper Tennessee, Elk River, and Duck River management units, and all physiographic provinces where the species is native. Within each population should be multiple viable, occupied sites to reduce the chance of extirpation. There are no population level genetic studies available for the ashy darter, so our evaluation of the species’ representation is based on the extent and variability of environmental diversity (habitat diversity) across the species’ geographical range.

The species has suffered a loss of connectivity due to dam construction, especially along the mainstem Tennessee River. Ashy darter populations are now isolated, preventing the exchange of novel or beneficial adaptations and reducing the species’ ability to migrate and found new populations or replace lost ones. Despite the isolation of populations, the species’ representation has been strengthened by its expansion in the Clinch River, and its widespread occurrence and persistence throughout its historical range.

Redundancy

Redundancy describes the ability of a species to withstand catastrophic events. It “guards against irreplaceable loss of representation” (Redford et al. 2011 p. 42; Tear et al. 2005 p. 841) and minimizes the effect of localized extirpation on the range-wide persistence of a species (Shaffer and Stein 2000, p. 308). It is characterized by having multiple, resilient populations distributed throughout the species ecological setting and across its range. For a species to exhibit greater redundancy the populations should not be completely isolated and immigration and emigration between populations should be achievable. The ashy darter is regarded to have medium redundancy because it maintains all but two historic populations (i.e., Tennessee River or tributaries near Florence, Alabama; South Chickamauga Creek, Georgia).

Currently, the ashy darter has two populations with high resilience, four populations with moderate resilience, and two populations that are extirpated. Connectivity between extant populations has been reduced, or likely eliminated, by major impoundments (e.g., Norris Lake). However, within most occupied tributary systems, ashy darter populations have few dispersal barriers between the mainstem and multiple tributaries. The connectivity within these systems decreases the effect of localized stochastic events that could be detrimental to these populations and lead to extirpation. The likelihood that a catastrophic event, such an extreme drought, or chemical spill would cause the extirpation of a population is highest for the Little River, Tellico River, and Emory River populations; and there is little or no opportunity for any eliminated population to recolonize naturally. Because these three populations are spaced apart and isolated, it is very unlikely a catastrophic event would result in simultaneous extirpations.

CHAPTER 5: FUTURE SCENARIOS AND SPECIES VIABILITY

In this chapter, we describe how current viability of the ashy darter may change over a period of 3-5 years and a period of 30 years. As in the current condition discussion, we evaluate the species viability in terms of resilience at the population scale, and representation and redundancy at the species scale (3 Rs). Here we describe three plausible future scenarios and whether there will be a change, from current conditions, to any of the 3 Rs under each scenario. Our future scenarios differ by considering variations that are predicted in three main elements of change: conservation activity, urbanization, and climate. These scenarios capture the range of plausible viability outcomes that the ashy darter will exhibit by 2050.

Since 2012, there have been efforts to reintroduce the ashy darter into its historical range in the Tellico River. While it is too soon to know if these efforts have been successful, they are important for improving redundancy. Landowner conservation in the Clinch, Duck, and Elk rivers will continue to improve water quality on private lands. We will use different levels of conservation commitment to determine differences in future scenarios.

The human population in the southeastern United States has grown at an average rate of 36.7% since 2000, making it the fastest growing region in the country (U.S. Census 2016). Within the range of the ashy darter, the Little River population appears to be most affected by urbanization. Through 2050, development and urban sprawl is expected to expand and influence areas that previously were unaffected by urbanization. Further, we assess how this increase in developed areas affects populations and the species as a whole.

To forecast future urbanization, we consider future scenarios that incorporate the SLEUTH (Slope, Land use, Excluded area, Urban area, Transportation, Hillside area) model, which simulates patterns of urban expansion that are consistent with spatial observations of past urban growth and transportation networks, including the sprawling, fragmented, “leapfrog” development that has been dominant in the southeastern United States. (Terando et al. 2014, p. 2). The extent of urbanized areas is predicted to increase across the southeastern United States by approximately 100 - 192 % based on the “business-as-usual” (BAU) scenario that expects future development to match current development rates (Terando et al. 2014, p. 1). We use this range of percent change in urbanization to develop our future scenarios described below.

In the Southeast, the clear trends in climate predictions are limited. Variability in weather is predicted to increase, resulting in more frequent and more extreme dry years and wet years over the next century, though increases in variability are already being observed (Mulholland et al. 1997, entire; Ingram et al. 2013, entire). Average and extreme temperatures are also expected to increase over time. More droughts will increase the likelihood that an ashy darter site is impacted by reduced river discharge, resulting in the reduction of affected populations’ condition. Droughts will also increase reliance on groundwater for irrigation of crops in the Tennessee River basin and may force municipalities to use secondary water sources, which has the potential to further reduce discharge throughout the basin. More wet weather and altered temperatures could result in reduced spawning success. We use either little or no noticeable change in climate over our projected time span, moderate change in climate, or strongly noticeable change in climate in the prediction of our future scenario.

Scenarios

Scenario F

In Scenario F, the ashy darter is being reintroduced into the Tellico River and private land conservation practices are being pursued in the Clinch, Duck, and Elk river populations. According to the SLEUTH model, urbanization increases in the Little River watershed through 2050. The current trend in climate continues, and within the next 3-5 years, a few populations are impacted by either drought or flood and the water warms slightly. In the long term, an increase in drought frequency affects all populations.

Population Resilience:

Clinch/Duck River Populations

Under Scenario F, the Clinch and Duck river populations will continue to experience a moderate level of private lands conservation. Additionally, urbanization is not expected to change from current levels. Drought frequency and intensity and stream temperatures will increase slightly. We expect the Clinch and Duck river populations to have a high resilience in the short term and the long term, and the same as current resilience.

Little River Population

Under Scenario F, the Little River has a greater than 95% certainty of undergoing urban growth in the lower portion of the river near Maryville, Tennessee, and in the area occupied by the ashy darter (Figure 5-1). We expect the Little River population to have a medium resilience in the short term and low resilience the long term, due to the projected urban growth and its effects on an already reduced population range.

Figure 5-1. SLEUTH model predictions for urban growth in the Little River watershed at 2020 and 2050.

Tellico/Emory/Elk River Populations

Under Scenario F, the Tellico, Emory, and Elk River populations will continue to experience a moderate level of private lands conservation. Urbanization is not expected to change from current levels. Frequency and intensity of drought and stream temperatures will continue at current levels. We expect these populations to have a medium resilience in the short term and the long term, the same as current resilience . South Chickamauga Creek/Tennessee River tributaries near Florence, Alabama

Under Scenario F, private lands conservation in South Chickamauga Creek and Tennessee River or tributaries near Florence, Alabama populations will continue at a low level. Additionally, urbanization will increase slightly from current levels. Frequency and intensity of drought, and stream temperatures will continue at current levels. We expect these populations to remain extirpated in the short term and the long term.

Species Representation:

Representation of the ashy darter is expected to slightly decline under Scenario F. The low resiliency of the Little River population will reduce overall representation. However, the species will continue to occupy all historical physiographic provinces and will retain a medium level of representation.

Species Redundancy:

Under Scenario F, the species has two populations with high resilience, three populations with moderate resilience, one population with low resilience, and two populations that are extirpated. The likelihood that a catastrophic event, such an extreme drought, or chemical spill will cause the extirpation of a population is highest for the Little River, Tellico River, and Emory River populations. There will be little or no opportunity for any eliminated population recolonize naturally.

The ashy darter will continue to have medium redundancy under Scenario F because it maintains all but two historic populations (i.e., Tennessee River or tributaries near Florence, Alabama; South Chickamauga Creek, Georgia).

Physical Connectivity Water Quality Occupancy Occurrence Occurrence Future Habitat Extent Complexity Condition Clinch River High High Medium High High High High Little River Low Medium Low High Low Low Low Tellico River* Medium High High High Low Low Medium Emory River High High Medium High Low Low Medium South Chickamauga Low Low Low Extirpated Extirpated Extirpated Extirpated Creek Elk River Medium Medium Medium High Medium Low Medium Tennessee River Low Low Low Extirpated Extirpated Extirpated Extirpated tributaries at Florence, AL Duck River High Medium High High Medium High High Table 5-1. Ashy darter resilience under scenario F (*indicates a stocked site/reintroduction effort).

Scenario W

In Scenario W, the ashy darter will continue to be reintroduced into the Tellico River and will be reintroduced into South Chickamauga Creek. Private land conservation practices are being pursued in the Clinch, Duck, and Elk River populations. According to the SLEUTH model, urbanization increases in the Little River watershed through 2050. The current trend in climate continues, but effects to populations by either drought, flooding, or slight warming of water in the short term and long term are minimal.

Population Resilience:

Clinch/Duck River Populations

Under Scenario W, the Clinch and Duck river populations will experience a high level of private lands conservation. Additionally, urbanization is not expected to change from current levels. Frequency and intensity of drought, and stream temperatures will continue at current levels. We expect the Clinch and Duck river populations to have high resilience in the short term and the long term, which is unchanged from current resilience.

Little River Population

Under Scenario W, the Little River has a greater than 95% certainty of urban growth in the lower portion of the river near Maryville, Tennessee, and in the area occupied by the ashy darter. However, private lands conservation will be prioritized in the watershed. We expect the Little River population to have a medium resilience in the short term and long term, the same as current resilience.

Tellico River Population

Under Scenario W, the Tellico River population will receive additional funding for reintroduction efforts. Additionally, urbanization is not expected to change from current levels. We expect this population to persist and grow due to reintroductions and to continue to have a medium resilience in the short and long term, the same as current resilience.

Emory/Elk River Populations

Under Scenario W, populations in the Emory and Elk rivers will experience moderate to high levels of private lands conservation. Additionally, urbanization is not expected to change from current levels. Frequency and intensity of drought, and stream temperatures will continue at current levels. We expect these populations to have a medium resilience in the short term and the long term, the same as current resilience.

South Chickamauga Creek

Under Scenario W, reintroduction efforts will be initiated in the South Chickamauga Creek population. In 30 years, we expect that the ashy darter population will begin to show growth. We expect this population at a minimum, would have low resilience in the short and long term, which is improved from its current state of extirpation.

Tennessee River tributaries near Florence, Alabama

Under Scenario W, the Tennessee River or tributaries near Florence, Alabama population will continue to see a low level of private lands conservation. Additionally, urbanization is not expected to change from current levels. Frequency and intensity of drought, and stream temperatures will continue at current levels. We expect the population to remain extirpated in the short term and the long term, with resilience remaining unchanged from the current level. Species Representation

Representation of the ashy darter is expected to improve slightly under the Scenario W. Reestablishment of a population in South Chickamauga Creek will improve representation, but overall, the species will retain a medium level of representation.

Species Redundancy:

Under Scenario W, the species has two populations with high resilience, four populations with moderate resilience, one reestablished population with low resilience, and one population that is extirpated. The likelihood that a catastrophic event, such an extreme drought, or chemical spill will cause the extirpation of a population is highest for the South Chickamauga Creek, Little River, Tellico River, and Emory River populations; and there will be little or no opportunity for any eliminated populations recolonize naturally. However, because these populations are in separate, unconnected tributaries, a single catastrophic event would affect one population rather than all of them simultaneously.

The ashy darter will continue to have medium redundancy, and maintains all but the Tennessee River or tributaries near Florence, Alabama population under Scenario W.

Physical Connectivity Water Quality Occupancy Occurrence Occurrence Future Habitat Extent Complexity Condition Clinch River High High Medium High High High High Little River Medium Medium Medium High Low Low Medium Tellico River* Medium High High High Low Low Medium Emory River High High Medium High Low Low Medium South Chickamauga Low Low Low Low Low Low Unknown? Creek* Elk River Medium Medium Medium High High Medium Medium Tennessee River Low Low Low Extirpated Extirpated Extirpated Extirpated tributaries at Florence, AL Duck River High Medium High High High High High Table 5-2. Ashy darter resilience under Scenario W (*indicates a stocked site/reintroduction effort).

Scenario S

In Scenario S, ashy darter reintroduction efforts into the Tellico River will cease. Additionally, private land conservation practices are reduced in the Clinch, Duck, and Elk River populations under this scenario. According to the SLEUTH model, urbanization increases in the Little River watershed through 2050. The current trend in climate continues, and within the next 3-5 years, a few populations will be slightly impacted by either drought or flood and the water warms slightly. In the long term, drought moderately impacts all populations.

Population Resilience:

Clinch/Duck River Populations

Under Scenario S, the Clinch and Duck river populations will experience a low level of private lands conservation. Additionally, urbanization is not expected to change from current levels. Frequency and intensity of drought, and stream temperatures will increase slightly. We expect the Clinch and Duck river populations to have a high resilience in the short term and the long term, the same as current resilience under this scenario.

Little/Tellico River Populations

Under the Scenario S, the Little River has a greater than 95% certainty of experiencing urban growth in its lower reach near Maryville, Tennessee and in the area occupied by the ashy darter. Private land conservation will not occur and water quality will decline. We expect these populations to become extirpated, with no resilience in the short term and long term, which is worse than the current level of medium resilience.

Emory/Elk River Populations

Under Scenario S, populations in the Emory and Elk rivers will experience a low level of private lands conservation. Additionally, urbanization is not expected to change from current levels. Frequency and intensity of drought, and current temperatures are expected to increase slightly. We expect these populations to have a medium resilience in the short term and the long term under this scenario, which is the same as current resilience.

South Chickamauga Creek/Tennessee River tributaries near Florence, Alabama

Under the Scenario S, the South Chickamauga Creek and Tennessee River or tributaries near Florence, Alabama populations will continue to experience a low level of private lands conservation. Additionally, urbanization is not expected to change from current levels. These rivers will experience ongoing levels of drought and temperatures. We expect these populations to remain extirpated in the short term and the long term under this scenario.

Species Representation:

Representation of the ashy darter is expected to slightly decline under Scenario S. The Little and Tellico river populations will become extirpated, reducing overall representation. However, the species will retain a medium level of representation.

Species Redundancy:

Under Scenario S, the species has two populations with high resilience, two populations with moderate resilience, and four populations that are extirpated. The likelihood that a catastrophic event, such an extreme drought, or chemical spill will cause the extirpation of a population is highest for the Emory River population, and there will be little or no opportunity for any eliminated population to recolonize naturally. Although one population currently with medium resiliency and one population currently being reintroduced are predicted to become extirpated under this scenario, the species will continue to have medium redundancy, with populations remaining in each ecoregion.

Physical Connectivity Water Quality Occupancy Occurrence Occurrence Future Habitat Extent Complexity Condition Clinch River High High Medium High High High High Little River Medium Medium Low Extirpated Extirpated Extirpated Extirpated Tellico River* Medium High High Extirpated Extirpated Extirpated Extirpated Emory River High High Medium High Low Low Medium South Chickamauga Low Low Low Extirpated Extirpated Extirpated Extirpated Creek Elk River Medium Medium Medium High Medium Low Medium Tennessee River Low Low Low Extirpated Extirpated Extirpated Extirpated tributaries at Florence, AL Duck River High Medium High High Medium High High Table 5-3. Ashy darter resilience under Scenario S (*indicates a stocked site/reintroduction effort).

Status Summary

Future viability

The future scenario assessment has sought to understand how viability of the ashy darter may change over the course of 30 years in the terms of resilience, representation, and redundancy. To account for considerable uncertainty associated with future projections, we defined three scenarios that would capture the breadth of changes likely to be observed in the Tennessee River watershed to which the ashy darter will be exposed. These scenarios considered three elements of change: conservation activity, urbanization, and climate. While we consider these scenarios plausible, we acknowledge that each scenario has a different probability of materializing at different time steps. To account for this difference in probability, probability categories (Table 5- 4) were used was used to describe the likelihood a scenario will occur (Table 5-5).

Confidence Terminology Explanation Very likely Greater than 90% certain Likely 70-90% certain As likely as not 40-70% certain Unlikely 10-40% certain Very unlikely Less than 10% certain Table 5-4. Explanation of confidence terminologies used to estimate the likelihood of a scenario (after IPCC guidance, Mastrandrea et al. 2011)

Scenario F Scenario W Scenario S 3-5 years Very Likely As likely as not As likely as not 20-30 years As likely as not As likely as not Likely Table 5-5. Likelihood of a scenario occurring at 3-5 and 30 years.

In Scenario F, it was assumed that ashy darter is being reintroduced into the Tellico River and private land conservation practices are being pursued in the Clinch, Duck, and Elk river populations. According to the SLEUTH model, urbanization increases in the Little River watershed through 2050. The current trend in climate continues, and within the next 3-5 years, a few populations are impacted by either drought or flood and the water warms slightly, and in the long term drought affects all populations.

Under Scenario F, the species has two populations with high resilience, three populations with moderate resilience, one population with low resilience, and two populations that are extirpated. This scenario will retain a medium overall redundancy and representation for the species. This scenario is considered very likely in 3-5 years, and as likely as not over the next 30 years.

In Scenario W, the ashy darter will continue to be reintroduced into the Tellico River and will be reintroduced into South Chickamauga Creek. Private land conservation practices are being pursued in the Clinch, Duck, and Elk river populations. According to the SLEUTH model, urbanization increases in the Little River watershed through 2050. The current trend in climate continues, but populations are not impacted by either drought, flooding, or slight warming of water in the short or long term.

Under Scenario W, the species has two populations with high resilience, four populations with moderate resilience, one population with unknown resilience, and one populations that is extirpated. This scenario will retain a medium overall redundancy and representation for the species. This scenario is considered as likely as not in 3-5 years and over the next 30 years.

In Scenario S, the ashy darter will no longer be reintroduced into the Tellico River. Private land conservation practices are reduced in the Clinch, Duck, and Elk river populations. According to the SLEUTH model, urbanization increases in the Little River watershed through 2050. The current trend in climate continues, and within the next 3-5 years, a few populations will be slightly impacted by either drought or flood and the water warms slightly, and in the long term drought moderately impacts all populations.

Under Scenario S, the species has two populations with high resilience, two populations with moderate resilience, and four populations that are now extirpated. This scenario will retain a medium overall redundancy and representation for the species. This scenario is considered as likely as not in 3-5 years, and likely over the next 30 years.

Uncertainty

Our analysis of current and future conditions contains uncertainty because we are unable to know the exact current status of the ashy darter and our future scenarios are projections based only on current trends. The following are uncertainties recognized in the report:

● Because of the nature of the ashy darter’s habitat and limited sampling in the past, it is impossible to truly know how many sites were historically occupied by this species. Similarly, sampling has been limited to known sites and sites where permission was granted to access the sites. It is possible that there could be additional sites. ● Without genetic material, it is unknown what level of differentiation exists between the populations of ashy darter. ● Future conservation efforts are dependent on funding opportunities and the capacities of our partners, so only a portion of actions may be taken.

Overall Summary

Currently, the ashy darter is known from six tributaries to the Tennessee River, which are isolated from one another by large impoundments. Because these six rivers are isolated, we defined each as a separate population of ashy darter. Currently, the species has two populations with high resilience, four populations with moderate resilience, and two populations that have been extirpated since circa 1854 and 1953. We estimate that the ashy darter has a medium adaptive potential (representation). The ashy darter has multiple populations occurring over a wide extent across the Tennessee River watershed, in the Upper Tennessee, Elk River, and Duck River management units, and all physiographic provinces where the species is native. There are no population level genetic

41 studies available for the ashy darter, so our evaluation of the species’ representation is based on the extent and variability of environmental diversity (habitat diversity) across the species’ geographical range. The ashy darter is regarded to have medium redundancy because it maintains all but two historic populations (i.e., Tennessee River or tributaries near Florence, Alabama; South Chickamauga Creek, Georgia).

The main stressors to the ashy darter are reduced range, impoundments, siltation, contaminants, and climate change. The species has suffered a loss of connectivity due to dam construction, especially along the mainstem Tennessee River. However, within most occupied tributary systems, ashy darter populations have few dispersal barriers between the main stem and multiple tributaries. Despite the isolation of populations, the species’ representation has been strengthened by its expansion in the Clinch River, and continues to be supported by its widespread occurrence and persistence throughout most of its historical range.

Our future scenarios assessment considered the current viability of the species to project future viability given plausible scenarios of conservation activity, urbanization, and climate. Under scenario F, two populations have high resiliency, three populations have medium resiliency, one population has low resiliency, and two populations are extirpated. Under scenario W, two populations have high resiliency, four populations have medium resiliency, one population has low resiliency, one populations has unknown resiliency, and one population is extirpated. Under scenario S, two populations have high resiliency, two populations have medium resiliency, and four populations are extirpated. Under all future scenarios, the ashy darter will continue to retain a medium level of representation and a medium level of redundancy.

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Appendices

Appendix 1. Existing critical habitat units found within the range of the Ashy darter.

River Species Critical Habitat Copper Creek Purple bean, 69 FR 53136 Oyster mussel, Cumberlandian combshell, Rough rabbitsfoot, Yellowfin madtom, 42 FR 47840 Fluted kidneyshell 78 FR 59556

Clinch River Purple bean, 69 FR 53136 Oyster mussel, Cumberlandian combshell, Rough rabbitsfoot, Slender chub, 42 FR 47840 Yellowfin madtom, Fluted kidneyshell, 78 FR 59556 Slabside pearlymussel

Elk River Fluted kidneyshell, 78 FR 59556 Slabside pearlymussel

Duck River Oyster mussel, 69 FR 53136 Cumberlandian combshell, Rabbitsfoot, Fluted kidneyshell, 78 FR 59556 Slabside pearlymussel Buffalo River Fluted kidneyshell, 78 FR 59556 Slabside pearlymussel

Appendix 2. Other federally listed or proposed species with range of the ashy darter.

River Federally Listed or Proposed Species Present Copper Creek, VA finerayed pigtoe Fusconaia cuneolus littlewing pearlymussel Pegias fabula oyster mussel Epioblasma capsaeformis purple bean Villosa perpurpurea rough rabbitsfoot Quadrula cylindrica strigillata shiny pigtoe Fusconaia cor duskytail darter Etheostoma percnurum yellowfin madtom Noturus flavipinnis Fluted kidneshell Ptychobranchus subtentum Clinch River, TN, VA Appalachian monkeyface Quadrula sparsa birdwing pearlymussel Lemiox rimosus cracking pearlymussel Hemistena lata Cumberland bean Villosa trabalis Cumberlandian combshell Epioblasma brevidens Cumberland monkeyface Quadrula intermedia dromedary pearlymussel Dromus dromas fanshell Cyprogenia stegaria finerayed pigtoe Fusconaia cuneolus Epioblasma torulosa green blossom pearlymussel gubernaculum littlewing pearlymussel Pegias fabula oyster mussel Epioblasma capsaeformis pink mucket Lampsilis abrupta purple bean Villosa perpurpurea rayed bean Villosa fabalis rough pigtoe Pleurobema plenum rough rabbitsfoot Quadrula cylindrica strigillata sheepnose Plethobasus cyphyus shiny pigtoe Fusconaia cor snuffbox Epioblasma triquetra spectaclecase Cumberlandia monodonta Epioblasma florentina walkeri tan riffleshell (=E. walkeri) Epioblasma florentina yellow blossom florentina fluted kidneyshell Ptychobranchus subtentum slabside pearlymussel Pleuronaia dolabelloides pygmy madtom Noturus stanauli slender chub Erimystax cahni

Appendix 2, continued.

Elk River, AL, TN Alabama lampmussel Lampsilis virescens birdwing pearlymussel Lemiox rimosus cracking pearlymussel Hemistena lata Cumberlandian combshell Epioblasma brevidens Cumberland monkeyface Quadrula intermedia dromedary pearlymussel Dromus dromas fanshell Cyprogenia stegaria finerayed pigtoe Fusconaia cuneolus littlewing pearlymussel Pegias fabula pale lilliput Toxolasma cylindrellus rabbitsfoot Quadrula cylindrica cylindrica rayed bean Villosa fabalis shiny pigtoe Fusconaia cor snuffbox Epioblasma triquetra spectaclecase Cumberlandia monodonta tan riffleshell Epioblasma florentina walkeri tubercled blossom pearlymussel Epioblasma torulosa torulosa turgid blossom pearlymussel Epioblasma turgidula Epioblasma florentina yellow blossom florentina fluted kidneyshell Ptychobranchus subtentum slabside pearlymussel Pleuronaia dolabelloides boulder darter Etheostoma wapiti snail darter Percina tanasi Duck River, TN birdwing pearlymussel Lemiox rimosus clubshell Pleurobema clava cracking pearlymussel Hemistena lata Cumberlandian combshell Epioblasma brevidens Cumberland monkeyface Quadrula intermedia littlewing pearlymussel Pegias fabula oyster mussel Epioblasma capsaeformis pale lilliput Toxolasma cylindrellus pink mucket Lampsilis abrupta rayed bean Villosa fabalis sheepnose Plethobasus cyphyus snuffbox Epioblasma triquetra spectaclecase Cumberlandia monodonta tan riffleshell Epioblasma florentina walkeri tubercled blossom pearlymussel Epioblasma torulosa torulosa turgid blossom pearlymussel Epioblasma turgidula

Appendix 2, continued.

Duck River, TN winged mapleleaf Quadrula fragosa Epioblasma florentina yellow blossom florentina pygmy madtom Noturus stanauli rabbitsfoot Quadrula cylindrica cylindrica fluted kidneyshell Ptychobranchus subtentum slabside pearlymussel Pleuronaia dolabelloides Buffalo River, TN pale lilliput Toxolasma cylindrellus spotfin chub Erimonax monachus rabbitsfoot Quadrula cylindrica cylindrica fluted kidneyshell Ptychobranchus subtentum slabside pearlymussel Pleuronaia dolabelloides