Sickle Darter (Percina williamsi) Species Status Assessment

Version 1.0

Photo courtesy of Crystal Ruble, Conservation Fisheries, Inc., Knoxville, Tennessee

U.S Fish and Wildlife Service South Atlantic – Gulf Region Atlanta, Georgia

March 2020

Draft Sickle Darter SSA

This document was prepared by Dr. Michael A. Floyd, U.S. Fish and Wildlife Service (Service), Kentucky Ecological Services Field Office, Frankfort, Kentucky.

The U.S. Fish and Wildlife Service greatly appreciates the assistance of Dr. Brian Alford (The Ohio State University), Todd Amacker (Todd Amacker Conservation Visuals), Bart Carter (Tennessee Wildlife Resources Agency (TWRA)), Luke Etchison (North Carolina Wildlife Resources Commission), Brian Evans (Service – Atlanta, Georgia), Krishna Gifford (Service – Hadley, Massachusetts), Kyler Hecke (The University of Tennessee), Karen Horodysky (Virginia Department of Game and Inland Fisheries (VDGIF)), Dr. Bernie Kuhajda (Tennessee Aquarium Conservation Institute (TNACI), David Matthews (Tennessee Valley Authority (TVA)), Dr. Dave Neely (TNACI), Michael Pinder (VDGIF), Pat Rakes (Conservation Fisheries, Inc. (CFI)), Judith Ratcliffe (North Carolina Natural Heritage Program), Jordan Richard (Service – Virginia Field Office), Steve Roble (Virginia Department of Conservation and Recreation), Crystal Ruble (CFI), J.R. Shute (CFI), Jeff Simmons (TVA), Kurt Snider (Service – Tennessee Field Office), Warren Stiles (Service – Tennessee Field Office), Dr. Matthew Thomas (KDFWR), Stephanie Williams (Tennessee Department of Environment and Conservation (TDEC)), and David Withers (TDEC), who provided helpful information and/or review of the draft document.

Suggested reference:

U.S. Fish and Wildlife Service. 2020. Sickle Darter (Percina williamsi) Species Status Assessment, Version 1.0. March 2020. Atlanta, Georgia. 87 pp.

Draft Sickle Darter SSA

Contents

EXECUTIVE SUMMARY ...... 2

CHAPTER 1. INTRODUCTION ...... 6

Background ...... 6 Analytical Framework ...... 6 Resiliency, Representation, Redundancy ...... 7

CHAPTER 2. SPECIES NEEDS AND DISTRIBUTION ...... 9

Biology and Life History ...... 9 Population Needs ...... 13 Species Needs ...... 14 Historical Range and Distribution ...... 15

CHAPTER 3. FACTORS INFLUENCING VIABILITY ...... 20

Habitat Loss and Degradation ...... 20 Reduced Range ...... 25 Climate Change ...... 27 Conservation Actions ...... 28

CHAPTER 4. CURRENT CONDITION AND SPECIES VIABILITY ...... 31

Methodology ...... 31 Habitat Elements ...... 33 Population Elements ...... 33 Current Population Status ...... 34 Current Species Representation ...... 51 Current Species Redundancy ...... 52 Summary of Current Condition ...... 52

CHAPTER 5. FUTURE SCENARIOS AND SPECIES VIABILITY ...... 54

Scenarios ...... 55 Summary of Future Viability ...... 66 Uncertainty ...... 67 Summary ...... 68

LITERATURE CITED ...... 69 APPENDIX A ...... 80 APPENDIX B ...... 82 APPENDIX C ...... 85

Draft Sickle Darter SSA 1 EXECUTIVE SUMMARY

Background

This species status assessment (SSA) describes the analytical process used by the U.S. Fish and Wildlife Service to assess the viability of the Sickle Darter, Percina williamsi. During this process, we evaluated the three conservation biology principles of resiliency, representation, and redundancy (or the “3Rs”) as they pertain to the species. The Sickle Darter is a small fish native to the upper Tennessee River drainage in North Carolina, Tennessee, and Virginia. It can be distinguished from most darters by the presence of a sickle-shaped suborbital bar (curved bar below the eye) and a small black bar subtending (extending below) a medial black spot at the base of the caudal (tail) fin. It can be distinguished from its closest relative, the Longhead Darter (Percina macrocephala) by its larger scales along the side of the body and around the caudal peduncle (posterior end of the body between the dorsal and caudal fins). The species typically occupies flowing pools over rocky, sandy, or silty substrates in clear creeks or small rivers. In these habitats, the species is most commonly observed around boulders, woody debris piles, or beds of water willow (Justicia americana). The species feeds primarily on mayflies and midges. Spawning occurs in late winter (February-March), and the species has a maximum lifespan of 3- 4 years.

Methodology

The SSA process can be categorized into three sequential stages. During the first stage, we considered the Sickle Darter’s life history and used the conservation biology principles of resiliency, redundancy, and representation to better understand the “needs” of populations and the species to maintain viability. The next stage involved an assessment of the historical and current condition of the species’ demographics and habitat characteristics. The final stage of the SSA involved making predictions about future viability while considering the species’ responses to anthropogenic and environmental influences that are likely to occur within its range. This process used the best available information to characterize viability as the ability of a species to sustain populations in the wild over time.

We delineated populations of the Sickle Darter using occurrence data obtained from peer- reviewed articles, unpublished survey reports, and survey records (1888 to present) contained in agency and partner databases (i.e., CFI, North Carolina Natural Heritage Program (NCNHP), Tennessee Department of Environment and Conservation (TDEC), Tennessee Wildlife Resources Agency (TWRA), Tennessee Valley Authority (TVA), and VDGIF). Based on these sources, we identified six extant Sickle Darter populations, each of which occurs in a distinct tributary system of the upper Tennessee River.

We made qualitative assessments of the current condition (viability) of each population through evaluations of components describing the species’ physical environment (Habitat Elements) or its demographics (Population Elements). Habitat elements included physical habitat, connectivity, and water quality. Population elements included reproduction, occurrence extent (total length of occupied streams compared to historical range), and occupied stream length. We further defined how each of these components might vary in terms of condition. These metrics

Draft Sickle Darter SSA 2 were selected because the supporting data were consistent across the range of the species and at a resolution suitable for assessing the species at the population level. The model output was a condition score for each Sickle Darter population that was then used to assess the Sickle Darter’s current condition across its range relative to the “3 Rs” of ecology: resiliency, redundancy, and representation.

The same methodology was used to assess the species’ condition and potential viability under three future scenarios. We chose to model these scenarios at 10, 30, and 50 years because we have data to reasonably predict potential habitat and water quality changes within this timeframe. Scenario 1 modeled the continuation of current trends where we assumed no change in urbanization rate, a moderate atmospheric emission scenario, and no changes in public ownership or conservation actions. Scenario 2 modeled a decreased rate of urbanization, lower emissions, and increased conservation activity across the species’ range. Scenario 3 modeled a decrease in forest cover, an increased rate of urbanization, higher emissions, and reduced conservation activity across the species’ range.

Draft Sickle Darter SSA 3 Conclusions

Current Condition

The Sickle Darter currently occupies portions of the Emory River system (Tennessee), the upper Clinch River system (Virginia), the Little River system (Tennessee), the North Fork Holston River system (Virginia), the Middle Fork Holston River system (Virginia), and the Sequatchie River system (Tennessee) (Figure 7) (Alford 2019, pp. 6-13; CFI and TDEC unpublished data). Populations within the French Broad River, Holston River, Powell River, and South Fork Watauga River systems are considered to be extirpated.

The Emory River and Little River populations exhibit moderate resiliency, as evidenced by the species’ persistence within these systems for over 45 years, recent and repeated evidence of reproduction and recruitment, a relatively long occupied reach in each system (≥ 22.5 km (≥ 14 mi)), and the quality of physical habitat and water quality in both systems. The remaining four populations exhibit low resiliency based on fewer documented occurrences, no evidence of recruitment, shorter occupied reaches, and reduced habitat and water quality conditions.

The species’ representation is low because of its reduced range (i.e., a loss of genetic diversity) and a loss of connectivity caused by dam construction. The Sickle Darter occupies only two of three historical ecoregions (Ridge and Valley and Southwestern Appalachians), likely reducing its ability to adapt to changing environmental conditions over time. The species’ redundancy is low based our evaluation of population resiliency and the amount of isolation observed across the species’ range. This increases the species’ vulnerability to catastrophic events.

Future Condition

Under Scenario 1 (continuation of current trend), conservation efforts by the Service and its partners are expected to continue, and no significant changes are expected with respect to land cover, urbanization, and climate. Three of the Sickle Darter’s six extant populations are expected to persist, with resiliency estimates remaining at current levels. Three extant populations, Clinch River, Middle Fork Holston River, and North Fork Holston River, are expected to be extirpated within 30 years due to small population size and continued degradation of physical habitat and water quality. The resiliency of a fourth population, Little River, is expected to decline within 50 years. The species’ redundancy and representation are expected to remain at low levels.

Under Scenario 2, (improving trend), we predict habitat conditions throughout the upper Tennessee River drainage to improve due to increased conservation efforts and improving land use practices (e.g. greater forest cover and reduced agricultural effects). Based on these factors, resiliency of all extant populations is expected to remain at current levels or strengthen, and the species is expected to be rediscovered or reintroduced into portions of the Powell River system and French Broad River system. The species’ redundancy will increase to a low-moderate level; representation is expected to remain at a low level.

Under Scenario 3 (worsening trend), habitat conditions are expected to decline within the upper Tennessee River drainage due to increased urbanization, more intensive agriculture, and

Draft Sickle Darter SSA 4 worsening climate trends. Combined with reduced conservation efforts, these factors will have a negative effect on population resiliency, resulting in extirpation of the Clinch River, North Fork Holston River, Middle Fork Holston River, and Sequatchie River populations. We also predict reduced resiliency for the Emory River and Little River populations within 30 years. Redundancy and representation will remain at low levels.

Draft Sickle Darter SSA 5 CHAPTER 1. INTRODUCTION

Background

This report summarizes the results of a Species Status Assessment (SSA) conducted for the Sickle Darter (Percina williamsi), a small benthic fish native to the upper Tennessee River drainage in North Carolina, Tennessee, and Virginia. In April 2010, the Sickle Darter was included in a listing petition from the Center for Biological Diversity and others (CBD 2010, entire) requesting that the U.S. Fish and Wildlife Service (Service) list 404 aquatic, riparian, and wetland species as endangered or threatened under the Endangered Species Act of 1973 (Act), as amended. In 2011, the Service found that this petition presented substantial scientific or commercial information indicating that listing may be warranted for 374 species, including the Sickle Darter (76 FR 59836; 76 FR 62260). Based on that finding, we conducted an SSA for the Sickle Darter to compile the best scientific and commercial data available regarding the species’ biology and any factors influencing its viability.

Analytical Framework

The SSA framework (USFWS 2016, entire; Smith et al. 2018, entire) is intended to be 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 easily updated as new information becomes available and to support all functions of the Endangered Species Program, including the cycle from Candidate Assessment to Listing and Recovery, as well as Consultations. As such, the SSA Report will be a living document upon which other decision documents, such as listing rules, recovery plans, and 5-year reviews, would be based if the species warrants listing under the Act.

The SSA will be the biological underpinning of the Service’s 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 does not result in a decision by the Service on whether the Sickle Darter should be proposed for listing as a threatened or endangered species under the Act. Instead, it provides a review of available information strictly related to the biological status of the species. The listing decision will be made by the Service after reviewing this document and all relevant laws, regulations, and policies, and the results of any proposed decision will be announced in the Federal Register, with appropriate opportunities for public review and input.

For the purpose of this assessment, we generally define viability as the ability of the Sickle Darter to sustain natural populations in river and stream systems over time. Using the SSA framework (Figure 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 (Smith et al. 2018, entire).

Draft Sickle Darter SSA 6

Figure 1. Species Status Assessment Framework

Resiliency

Resiliency describes the ability of a species to withstand stochastic disturbance (arising from random factors). Resiliency is positively related to population size, growth rate, and fecundity and may be influenced by connectivity among populations. Generally, populations need sufficient numbers of individuals within habitats of adequate area and quality to maintain survival and reproduction in spite of disturbance. Resilient populations are better able to withstand disturbances such as random fluctuations in birth rates (demographic stochasticity), variations in rainfall (environmental stochasticity), or the effects of anthropogenic activities.

Representation

Representation describes the ability of a species to adapt to changing environmental conditions over time and is characterized by the breadth of genetic and environmental diversity within and among populations (Shaffer and Stein 2000, p. 308). 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 characteristics across the geographical range and other factors as appropriate.

Redundancy

Redundancy describes the ability of a species to withstand catastrophic events (a rare destructive natural event or episode involving many populations). 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). Generally speaking, redundancy is best achieved by having multiple, resilient (connected) populations widely distributed across the species’ range. Having multiple populations reduces

Draft Sickle Darter SSA 7 the likelihood that all populations are affected simultaneously, while having widely distributed populations reduces the likelihood of populations possessing similar vulnerabilities to a catastrophic event. Given sufficient redundancy, single or multiple catastrophic events are unlikely to cause the extinction of a species. Therefore, as redundancy increases, species viability also increases.

To evaluate the biological status of the Sickle Darter both currently and into the future, we assessed a range of conditions to allow us to consider the species’ resiliency, redundancy, and representation (together, the 3Rs). This SSA Report provides a thorough assessment of biology and natural history and assesses demographic risks, stressors, and limiting factors in the context of determining the viability and risks of extinction for the species. 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 Sickle Darter.

Draft Sickle Darter SSA 8 CHAPTER 2. SPECIES NEEDS AND DISTRIBUTION

Biology and Life History

Taxonomy and Genetics

The Sickle Darter (Percina williamsi) is a member of the Class Actinopterygii (ray-finned fishes), Order Perciformes, and Family Percidae (perches) (Etnier and Starnes 1993, pp. 18–25). It was described by Page and Near (2007, pp. 606-608), who examined geographic variation in morphology across the range of the Longhead Darter (P. macrocephala Cope) and determined that individuals from the upper Tennessee River drainage represented a distinct species (P. williamsi). Page and Near (2007, entire) based their determination on a series of scale counts and haplotype differences in the cytochrome b gene (mitochondrial DNA). The Sickle Darter’s taxonomy and common name have been accepted by the scientific community, as evidenced by the species’ inclusion in Page et al. (2013, pp. 142) – a list of common and scientific names of fishes from the United States, Canada, and Mexico published by the American Fisheries Society (7th edition).

Page and Near (2007, p. 611) analyzed cytochrome b DNA sequences for five Sickle Darter specimens collected from the Little River and Emory River, Tennessee. Page and Near (2007, pp. 610-611) found unique haplotypes in all five specimens, and haplotypes within a sampling area (i.e., Little River or Emory River) were more similar than between the two sampling areas. Page and Near (2007, pp. 610-611) did not evaluate individuals from the Clinch River (Copper Creek), Holston River (North Fork Holston River and Middle Fork Holston River), and Sequatchie River systems, so it is unclear if these patterns would hold across the species’ range. Additional collections are needed from across the species’ range to gain a complete and thorough understanding of the species’ population genetics.

Physical Description

The Sickle Darter is a small, compressed fish, with a maximum total length of about 120 mm (4.7 in.) (Figure 2) (Etnier and Starnes 1993, p. 576). The species is characterized by a long, slender body and an elongated, pointed snout (Page and Near 2007, pp. 607-608). The body color is brown to olive above and white to pale yellow below. A thin black stripe extends along the top of the body from the head to the rear of the second dorsal fin. Eight to 14 black blotches extend along each side; the blotches may be fused, forming a black stripe with undulating margins. A narrow yellow stripe may be present on each side above the dark blotches; the stripe is most prominent in juveniles and small adults. The lower sides of the body are typically covered by multiple black specks. A sickle-shaped suborbital bar (or “teardrop”) extends below each eye to the underside of the head. The caudal (tail) fin has a black spot at its base and a black bar extending from the spot to about the ventral edge of the caudal fin. The first dorsal fin has a dusky or black margin, followed by a clear band and a basal dusky band. The dusky band may be bordered by a narrow clear band at the base of the fin. The remaining fins are mostly clear with diffuse dark bands.

Draft Sickle Darter SSA 9

Figure 2. Left lateral view of a Sickle Darter, Emory River, Morgan County, Tennessee (Photo courtesy of Todd Amacker Conservation Visuals, www.toddamacker.com).

Habitat

The Sickle Darter typically occurs in slow flowing pools (mean velocities of 6-7 cm/s (0.20-0.23 ft/s)) of larger, upland creeks and small to medium rivers (Page 1983, p. 37; Kuehne and Barbour 1983, p. 37; Etnier and Starnes 1993, p. 576; Page and Near 2008, p. 609; Alford 2019, p. 8) (Figure 3). Occupied streams tend to have good water quality, with low turbidity and negligible siltation (Etnier and Starnes 1993, p. 576; Alford 2019, p. 9). In these habitats, the species is most often associated with clean sand-detritus or gravel-cobble-boulder substrates, stands of American Water Willow (Justicia americana), or woody debris piles at depths ranging from 0.4- 1.0 m (1.3-3.3 ft) (Etnier and Starnes 1993, p. 576; Page and Near 2008, p. 609; Alford 2019, p. 8). Alford (2019, p. 10) observed Sickle Darters most often in shallow pools near the bank or adjacent to vegetated gravel bars, but these pools were always adjacent to swift currents. Streams supporting Sickle Darters had wetted widths ranging from 9-33 m (29.5-108.3 ft), and riparian canopy cover in these streams ranged from open (41%) to nearly closed (91%) (Alford 2019, p. 8). The species spends most of its time in the water column, often hovering a few centimeters (inches) above the stream or river bottom (Etnier and Starnes 1993, p. 576). The prominent black stripe or series of blotches along the side of P. williamsi is characteristic of darters living near vegetation in flowing pools (Page 1983, p. 177).

Feeding Habits

Sickle Darters feed primarily on larval mayflies (i.e., families Baetidae and Heptageniidae) and midges (family Chironomidae); minor prey items include riffle beetles (family Elmidae), caddisflies (family Hydropsychidae), dragonflies (family Gomphidae), and several other groups of aquatic macroinvertebrates (Page and Near 2007, pp. 609-610; Alford 2019, p. 10). Crayfishes have been reported as a common food item for the closely related Longhead Darter (Page 1978, p. 663); however, crayfishes were absent from 28 gut samples of the Sickle Darter examined by Alford (2019, p. 10). The long snout and large mouth of the Sickle Darter likely facilitates the capture and ingestion of larger prey items such as heptageniid mayflies (Page and Near 2007, p. 609). Etnier and Starnes (1993, p. 576) observed Sickle Darters in the Little River

Draft Sickle Darter SSA 10

Figure 3. Sickle Darter Habitats: Rock Creek at Tennessee Highway 62, Morgan County, Tennessee (top L); Emory River at Greasy Creek Road bridge , Morgan County, Tennessee (top R); Middle Fork Holston River near Chilhowie, Smyth County, Virginia (middle L); Little River downstream of US Highway 441 bridge, Blount County, Tennessee (middle R); and Sequatchie River near Pikeville, Bledsoe County, Tennessee (bottom). (Photos courtesy of Dr. Brian Alford, The University of Tennessee).

Draft Sickle Darter SSA 11 deftly plucking food items from the surfaces of stones and other underwater objects while swimming above the stream bottom.

Reproduction and Life History

In winter, Sickle Darters have been observed in deep pools (depths of up to 3 m (10 ft)) or in slow-flowing, shallow pools in close proximity to cover (Etnier and Starnes 1993, p. 576; Service 2020, p. 1). The species migrates to shallow, gravel shoals (riffles) in late winter or early spring (February-March) to spawn (Figure 4) (Etnier and Starnes 1993 p. 576). Spawning begins when stream water temperatures reach 10-16°C (Table 1) (Petty et al. 2017, p. 3). Breeding males darken in coloration enough to obscure their body pattern, while breeding females may darken without obscuring body pattern. In the Emory River system, Tennessee, Page and Near (2007, p. 609) collected reproductive male and female specimens from a riffle at a depth of 25 cm (10 in) and at a temperature of 8oC (46.4oF). The mature ova of the female equaled 27% of her body mass, and 100 of the 355 mature ova had a mean diameter of 1.62 mm (0.06 in). In the Little River system, Tennessee, eggs laid in March hatched in 27 days at an average stream temperature of 10oC (50oF), with larvae emerging at a length of 10 mm (0.4 in) (Etnier and Starnes 1993, p. 576). The incubation period is likely shorter (about two weeks) when stream temperatures are higher (Service 2020, p. 1). Similar to the Longhead Darter, the pelagic larvae presumably feed on zooplankton and other small macroinvertebrates after depleting yolk sac nutrients (Etnier and Starnes 1993, p. 576; Petty et al. 2017, p. 3). The pelagic larvae become demersal (move to the stream bottom) in about 30 days (Petty et al. 2017, p. 3).

Alford (2019, pp. 7-8, 23) identified multiple size-classes and age groups across the Sickle Darter’s range. Approximate age groups and size classes included age 0 (≤40 mm TL), age 1 (59-85 mm TL), and age 2+ (> 85 mm TL). Page (1978, pp. 662-223) reported three possible age groups for 148 Longhead Darters collected from the Green River, Kentucky, but ages of larger specimens (age 1+) were uncertain because scale annuli were not discernible on most specimens and direct aging of bony structures was not possible. The observed sex ratio of Longhead Darters in the Green River was 1.5 male: 1.0 female, but this ratio could be an artifact of sampling bias (Page 1978, pp. 662-663). Similar to the Longhead Darter, sexually maturity of males occurs at the end of the first year of life (age 11-13 months), while sexual maturity of females occurs at the end of their second year of life (age 22-25 months) (Page 1978, p. 663; Petty et al. 2017, p. 3). Male Sickle Darters tend to be larger than females of the same age (Petty et al. 2017, p. 3).

No information is available on movement behavior of the Sickle Darter; however, studies of movement behavior in two related species, the Longhead Darter and the Frecklebelly Darter (Percina stictogaster) suggest that the Sickle Darter may have similar migratory behavior (Eisenhour et al. 2009, pp. 7-12; Eisenhour et al. 2011, pp. 14-15; Eisenhour and Washburn, pp. 19-24). Eisenhour et al. (2011, pp. 14-15) provided evidence for seasonal movements of the Longhead Darter in Kinniconick Creek, Kentucky. Eisenhour suspected that Longhead Darters were moving from downstream to upstream reaches of Kinniconick Creek following periods of severe drought. This would explain how the species continued to be observed in upstream reaches despite local extirpations or periods of poor recruitment. Eisenhour and Washburn.

Draft Sickle Darter SSA 12 (2016, pp. 19-24) studied the movement behavior of a related species, the Frecklebelly Darter, in the Red River, Kentucky. The Frecklebelly exhibits the same “pelagic” behavior as the Sickle Darter and has a similar body shape and pigment pattern. Eisenhour and Washburn (2016, pp. 19-24) documented frequent upstream and downstream movements of the Frecklebelly Darter, more than any of the other five darters in the study. We speculate that Sickle Darters may exhibit similar behaviors in the upper Tennessee River drainage. The pelagic behavior of juveniles and adults supports the assumption that Sickle Darters have some ability to disperse and/or move within a stream system.

Population Needs

Each population of the Sickle Darter needs to be able to withstand, or be resilient to, stochastic events or disturbances. Even though these events may happen infrequently, they are reasonably likely to occur and can drastically alter Sickle Darter habitats where they occur. Classic examples of stochastic events include drought, major floods, fire, and landslides (Chapin et al. 2002 p. 285 - 288). To be resilient to stochastic events, populations of Sickle Darters need to have a large number of individuals (abundance), cover a large area (spatial extent), and the area occupied needs to occur in multiple non-linear waterways or watersheds (spatial complexity). 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.

Figure 4. Sickle Darter life cycle.

Draft Sickle Darter SSA 13

Species Needs

For a species to persist over time, it must exhibit attributes across its range that relate to either representation or redundancy (Figure 5). Representation is characterized by the breadth of genetic and environmental diversity within and among populations. For the Sickle Darter to exhibit adequate representation, resilient populations should occur in the ecoregions (i.e., Blue Ridge, Ridge and Valley, Southwestern Appalachians) to which it is native (Woods et al. 2003, entire; Griffith et al. 1998, entire); these populations should occur at the widest extent possible across the historical range of the species; and they should occupy multiple tributaries in systems where they are native. The breadth of morphological, genetic, and behavioral variation should be preserved to maintain the evolutionary variation of the species. Finally, connectivity should be maintained between representative populations because it allows for the exchange of novel and beneficial adaptations (Figure 5).

Table 1. Overview of needs of individual Sickle Darters based on our knowledge of the species’ biology, ecology, and life history summarized above.

Life Stage Resources Needed Information Source Fertilized Egg Water temperatures 10-16oC (50-61oF); Page and Near 2007, relatively silt-free, gravel and sand p. 609; Petty et al. substrates in riffles during late winter or 2017,p. 3 early spring (February – March). Larvae Pelagic larvae feed on zooplankton and Etnier and Starnes other small macroinvertebrates; become 1993, p. 576; Petty et demersal (move to stream bottom) about al. 2017, p. 3 30 days after hatching. Juveniles Habitats presumably similar to adults. N/A

Adults Slow flowing pools (mean velocities of 6-7 Etnier and Starnes cm/s (0.20-0.23 ft/s)) of larger, upland 1993, p. 576; Page and creeks and small to medium rivers; stream Near 2007, p. 609; habitats with good water quality, including Petty et al. 2017, p. 3, low turbidity and negligible siltation; Alford 2019, p. 8 species most often associated with clean sand-detritus or gravel-cobble-boulder substrates, stands of American Water Willow (Justicia americana), or woody debris piles at depths ranging from 0.4-1.0 m (1.3-3.3 ft); food availability - mayflies, midges, and other aquatic invertebrates; water temperatures of 10-16oC (50-61oF) for successful spawning (typically February to March).

Draft Sickle Darter SSA 14

Redundancy for the Sickle 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 redundancy, it must have multiple 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 (Figure 5).

Figure 5. How resiliency, representation, and redundancy are related to species viability.

Historical Range and Distribution

To determine the historical and current range of the Sickle Darter, we reviewed all available occurrence data (1888 to present) associated with peer-reviewed research (e.g., Page 1978, Etnier and Starnes 1993, Page and Near 2007), unpublished survey reports (e.g., Petty et al. 2017, Alford 2019), university collections (e.g., The University of Tennessee’s Etnier Ichthyology Collection), agency databases (i.e., NCNHP, TDEC, TWRA, TVA, and VDGIF), and other sources (e.g., CFI, TNACI). The Service’s Tennessee Ecological Services Field Office recently funded a range-wide status survey for the Sickle Darter (Alford 2019, entire); we have incorporated those results into the SSA.

Draft Sickle Darter SSA 15 Historical Range

The species’ historical range (prior to 2005) included nine tributary systems of the upper Tennessee River drainage in North Carolina, Tennessee, and Virginia: Emory River, Clinch River, Powell River, Little River, French Broad River, North Fork Holston River, Middle Fork Holston River, South Fork Holston River, and Watauga River (Figure 6, Table 2) (Menhinick et al. 1974, p. 42; Page 1984, pp. 659-660; Etnier and Starnes 1993, p. 576; Page and Near 2007, pp. 608-609). Jordan (1890, pp. 142-147) provided the first records of the species during explorations of the Allegheny region of North Carolina, Tennessee, and Virginia in the summer of 1888. Jordan (1890, pp. 142-147) reported a single specimen of the Sickle Darter from the Middle Fork Holston River at Glade Spring (Smyth County, Virginia) and three specimens from the North Fork Holston River at Saltville (Smyth County, Virginia). Evermann and Hildebrand (1914, p. 448) provided an additional early record in 1893 ̶ a single specimen collected from Indian Creek, a tributary of the Powell River in Claiborne County, Tennessee. Additional surveys conducted between 1894 and 2004 produced records from 12 additional streams (Table 2). The greatest number of historical occurrence records are available from the Emory River (Morgan County, Tennessee) and Little River (Blount County, Tennessee) systems.

Current Range

The Sickle Darter continues to occupy portions of the Emory River system (Tennessee), the upper Clinch River system (Copper Creek, Virginia), the Little River system (Tennessee), the North Fork Holston River system (Virginia), and the Middle Fork Holston River system (Virginia) (Figure 7) (Alford 2019, pp. 6-13; CFI and TDEC unpublished data). The species appears to be most abundant, with evidence of reproduction and recruitment, in the Emory River system (Morgan County, Tennessee) and Little River system (Blount County, Tennessee). The species likely occurs in low densities in Copper Creek (upper Clinch River), where recent records consist of a single specimen observed by CFI in 2008 (CFI unpublished data). Records of the species in the Middle Fork Holston River and North Fork Holston River are also rare, consisting of 11 occurrences since 2005 (Alford 2019, p. 26; CFI and TVA unpublished data). In 2014, TVA biologists discovered a single specimen of the Sickle Darter in the Sequatchie River, Bledsoe County, Tennessee – a new collection site and range extension for the species (Alford 2019, p. 2; TVA unpublished data). In 2019, Alford (2019, p. 6) confirmed the species’ presence in the Sequatchie River, observing another specimen at the site.

The species has not been observed in North Carolina since 1940 (French Broad River, Buncombe County) and is now considered to be extirpated from the upper French Broad River system (Menhinick et al. 1974, p. 42; Etnier 1997, p. 78; Page and Near 2007, p. 610). The species is also likely extirpated from the Powell River system, Tennessee (not observed since 1893); South Fork Holston River system, Tennessee (not observed since the 1940s); Little Pigeon River (lower French Broad River system), Tennessee (not observed since the 1970s); and the Watauga River system, Tennessee (not observed since the 1980s) (Alford 2019, pp. 12-13; CFI, TDEC, and TVA unpublished data). We provide a detailed overview of the species’ current range and population resiliency in the Current Condition and Species Viability section (Chapter 4).

Draft Sickle Darter SSA 16

Figure 6. Historical distribution of the Sickle Darter in the upper Tennessee River drainage, North Carolina, Tennessee, and Virginia based on positive occurrence records (1888-2004).

Draft Sickle Darter SSA 17 Table 2. Summary of Sickle Darter historical occurrences

Tributary Collection Stream County, State Reference(s)* System Year(s) Clinch River Russell, VA 1992 VDGIF

Copper Creek Scott, VA 1969-1971, Page (1978), USNM, RC Clinch River 1981, 1992 VDGIF Little River Russell, VA 1967 Jenkins and Burkhead (1994), VDGIF Indian Creek Claiborne, TN 1893 Evermann and Hildebrand Powell River (1914), Page (1978), TDEC Emory River Morgan, TN 1975 Page (1978), TDEC, TVA, UT Emory River Rock Creek Morgan, TN 1971, 1996, TDEC, TVA, UT, YPM 2003 Little River Blount, TN 1969-1972, Page (1978), AUM, CFI, 1974-1975, INHS, NCSM, TDEC, Little River 1979, 1981- TVA, UAIC, UF, GMNH, 1982, 1985- UT, VDGIF, YPM 2004 French Broad River Buncombe, NC 1940 Menhinick et al. (1974), Knox, TN Etnier 1997), CUMV, NCNHP French Broad West Prong Little Pigeon River Sevier, TN 1937 Page (1978), UMMZ River Walden Creek (trib of W Prong Sevier, TN 1978 Page (1978), Etnier et al. Pigeon R) (1979), TDEC North Fork North Fork Holston River Smyth, VA 1888, 1928, Jordan (1888), Page Holston River 1971, 1973- (1978), Feeman (1986), 1975, 1986, Hill et al. 1989, Jenkins 2002 and Burkhead (1994), OSUM, RC, TVA, UF, UT, VDGIF Middle Fork Middle Fork Holston River Smyth, VA 1888, 1937 Jordan (1888), Jenkins Holston River and Burkhead (1994), TVA, UT, VDGIF South Fork South Fork Holston River Sullivan, TN 1947 Page (1978), TDEC, Holston River UMMZ Doe River Carter, TN 1984 TDEC, UT Watauga River Watauga River Carter, TN 1947 Page (1978), TDEC, UMMZ *Occurrence records obtained from published literature, agency databases, and museum collections: Auburn University Museum (AUM); Conservation Fisheries, Inc. (CFI); Cornell University Museum of Vertebrates (CUMV); Georgia Museum of Natural History (GMNH); Illinois Natural History Survey (INHS); North Carolina Natural Heritage Program (NCNHP), North Carolina State Museum (NCSM); Ohio State University Museum (OSUM); Roanoke College Freshwater Fish Collection (RC); Tennessee Department of Environment and Conservation (TDEC); Tennessee Valley Authority (TVA); University of Alabama Ichthyological Collection (UAIC); University of Florida (UF); University of Michigan Museum of Zoology (UMMZ); University of Tennessee (UT), U.S. National Museum (USNM); Virginia Department of Game and Inland Fisheries (VDGIF); and Yale Peabody Museum (YPM).

Draft Sickle Darter SSA 18

Figure 7. Current (2005-2019) and historical distribution of the Sickle Darter in the upper Tennessee River drainage, North Carolina, Tennessee, and Virginia, based on positive collection records (1888-present).

Draft Sickle Darter SSA 19 CHAPTER 3. FACTORS INFLUENCING VIABILITY In the following discussion, we summarize negative and positive factors that may affect the viability of the Sickle Darter. We have identified four major factors: habitat loss and degradation (i.e., siltation, water quality degradation, and impoundment effects), reduced range, climate change, and conservation actions.

Habitat Loss and Degradation

Habitat loss and degradation is the principal negative factor affecting the viability of the Sickle Darter across its historical range in North Carolina, Tennessee, and Virginia. The primary stressors associated with this factor are siltation (excess sediments suspended or deposited in a stream), water quality degradation (pollution), and hydrologic alteration (impoundments) (Etnier et al. 1979, pp. 1-3; Etnier and Starnes 1993, p. 576; Jenkins and Burkhead 1993, pp. 101-106; Etnier 1997, p. 78; Page and Near 2007, p. 610; TDEC 2014, pp. 47-50; TDEC 2017, pp. 51- 106; Ahlstedt et al. 2016, pp. 13-14; VDEQ 2018 (Appendix 5), pp. 2313-2531; Alford 2019, p. 2).

Siltation

Etnier and Starnes (1993, p. 576), Jenkins and Burkhead (1993, pp. 101-106), Page and Near (2007, p. 610), and Alford (2019, p. 2) identified siltation as a principal threat to the Sickle Darter; however, the species is sometimes observed in habitats (e.g., Emory River) with at least low to moderate levels of siltation on some substrates (Service 2020, p. 3). Excessive stream siltation is typically caused by soil erosion and stormwater runoff associated with upland land use activities (e.g., agriculture, forestry, mining, road or pipeline construction, and general urbanization), but it can also be caused by activities that directly destabilize stream channels and remove riparian vegetation (e.g., dredging or channelization, construction projects, land development). Excessive sediments can accumulate and cover the stream bottom, filling the interstitial spaces with finer substrates and homogenizing and decreasing the available habitat. In severe cases, sediment can bury even larger substrate particles such as cobble and boulders. Siltation can affect fishes through abrasion of gill tissues, suffocation of eggs or larvae, reductions in disease tolerance, degradation of spawning habitats, modification of migration patterns, and reductions in food availability (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).

Siltation (or sedimentation) continues to be one of the primary stressors of streams in the upper Tennessee River drainage (TDEC 2010, pp. 43-45; TDEC 2014, pp. 48-50; TDEC 2017, pp. 51- 128; VDEQ 2018, pp. 89-91). Sediments can originate from a variety of sources, but state agencies continue to cite land use practices associated with agriculture, land development, and resource extraction (e.g., coal mining) as primary sediment sources (TDEC 2010, pp. 56-65; TDEC 2014, pp. 62-69; VDEQ 2018 (Appendix 5), pp. 2313-2531). Unrestricted livestock access occurs on many streams and has the potential to cause siltation and other habitat disturbance (Fraley and Ahlstedt 2000, pp. 193–194). Grazing may reduce water infiltration rates and increase stormwater runoff; trampling and vegetation removal increases the probability of erosion and siltation (Brim Box and Mossa 1999, p. 103). Croplands have the potential to contribute large sediment loads during storm events, thereby causing increased siltation and

Draft Sickle Darter SSA 20 potentially introducing harmful agricultural pollutants such as herbicides and pesticides. Activities associated with land development contribute to siltation through land conversion (ground disturbance), stream channelization, and removal of riparian vegetation. Stream channelization dramatically alters stream dimensions, stream flow, and instream habitat quality, leading to increased channel instability, erosion of bed sediments, loss of riparian vegetation, and siltation (Allan 2004, p. 262; Allan and Castillo 2007, p. 327). The loss of riparian vegetation contributes to siltation through bank destabilization and the removal of submerged root systems that help to hold sediments in place (Barling and Moore 1994, p. 544; Beeson and Doyle 1995, p. 989; Allan 2004, p. 262; Hauer and Lamberti 2006, pp. 721–723; Minshall and Rugenski 2006, pp. 721–723).

Land use practices such as surface coal mining, oil and gas drilling, and logging also contribute to siltation of stream habitats in the upper Tennessee River drainage, especially the upper Clinch and Powell River systems (TDEC 2017, pp. 94-97; Zipper et al. 2016, pp. 609-610; VDEQ 2018 (Appendix 5), pp. 2313-2531). Activities (e.g., land clearing, road construction, excavation) associated with these land use practices can produce new road networks and large areas of bare soil that, if not protected or controlled through erosion control practices, can contribute large amounts of sediment to streams during storm events. Land use practices associated with surface coal mining, such as the placement of valley fills, influence a small portion of the species’ range, but these activities 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). Similarly, logging activities can adversely affect Sickle Darters through removal of riparian vegetation, direct channel disturbance, and sedimentation of instream habitats. During logging activities, sedimentation occurs as soils are disturbed, the overlying leaf or litter layer is removed, and sediment is carried overland from logging roads, stream crossings, skid trails, and riparian zones during storm events. Logging impacts on sediment production can be considerable, but access and haul roads often produce more sediment than the land harvested for timber (Brim Box and Mossa 1999, p. 102).

Siltation has likely played a role in the Sickle Darter’s current distribution, as the pools and slow raceways (runs) occupied by the species would be impacted by sediment deposition earlier and more readily than habitats with faster moving water (e.g., riffles) (Eisenhour et al. 2009, p. 11). Etnier and Starnes (1993, p. 576) considered the Sickle Darter to be intolerant of siltation, a common sensitivity of darters spending much of their time in pool habitats.

Water Quality Degradation (Pollution)

Information is lacking on the Sickle Darter’s tolerance to specific pollutants, but a variety of contaminants continue to degrade stream water quality within the upper Tennessee River drainage, and these pollutants may affect the Sickle Darter (Locke et al. 2006, p. 197, 202-203; TDEC 2010, pp. 42-48; TDEC 2014, pp. 47-53; Zipper et al. 2016, p. 604; TDEC 2017, pp. 51- 106; VDEQ 2018 (Appendix 5), pp. 2313-2531). Major pollutants within the upper Tennessee River drainage include pathogens, domestic sewage, animal waste, nutrients, metals, and toxic organic compounds.

Draft Sickle Darter SSA 21

Pathogens (fecal indicator bacteria) are a leading cause of stream pollution across the Sickle Darter’s range (Hampson 2000, p. 7; TDEC 2014a, pp. 47-53, TDEC 2017, pp. 51-106; VDEQ 2018 (Appendix 5), pp. 2313-2531). The effect of high bacterial levels on the Sickle Darter is unknown, but high bacterial concentrations may be an indicator of degraded stream conditions (e.g., low dissolved oxygen) or they may indicate the presence of other pollutants of concern that could harm the species. In rural areas, livestock waste is the primary source of bacterial contamination. Pasture is the dominant agricultural land use in the upper Tennessee River drainage, so it is not surprising that animal waste can quickly enter streams during storm events, leading to high bacterial levels. Deteriorating and leaky sewage systems, faulty sewage treatment plants, urban runoff, and combined sewer overflow (CSO) systems are the primary sources of bacterial contamination in urban streams (Hampson 2000, p 7). During wet periods, CSOs overflow occasionally, discharging excess wastewater directly to nearby streams, rivers, or lakes. These sewer systems contain not only stormwater, but also untreated human and industrial waste and toxic materials that could be hazardous to aquatic systems. This can be a major water pollution concern for cities with CSO systems, but we suspect that CSO impacts are localized in the upper Tennessee River drainage and do not represent a significant factor influencing the Sickle Darter’s viability.

Elevated nutrient concentrations (i.e., phosphorus, nitrate/nitrate, ammonia) are another leading cause of stream pollution in the upper Tennessee River drainage (Hampson 2000, p. 8; Price et al. 2011, pp. III-1, IV-1; TDEC 2014, p. 50; TDEC 2017, pp. 51-106; VDEQ 2018, pp. 89-91). Primary sources include wastewater treatment facilities, urban and industrial stormwater systems, and agricultural runoff (i.e., livestock waste and synthetic fertilizers) (Hampson 2000, p. 9; TDEC 2014, p. 50). Elevated concentrations of nutrients (a process called eutrophication) can result in dense growths of algae and other nuisance aquatic plants (Carpenter et al. 1998, entire). Community composition in these streams will likely shift toward aquatic species that can tolerate the excessive growths of algae and the dramatic fluctuations in dissolved oxygen levels (TDEC 2014, p. 50). Subsequent decay of algal blooms can result in foul odors and reduced dissolved oxygen levels, which are harmful to aquatic life. Ammonia can cause direct toxic effects on aquatic life if levels are excessive and aquatic organisms cannot excrete the toxicant sufficiently (EPA 2013, p. 52192). This can lead to a toxic buildup in internal tissues and blood and potentially lead to death (EPA 2013, entire).

Other stream pollutants in the upper Tennessee River drainage include organic compounds (e.g., PCBs, dioxins), metals (e.g., mercury, iron, and manganese), and pesticides (Hampson 2000, pp. 14-19; Soucek et al. 2000, entire; Soucek et al. 2003, entire; Locke et al. 2006, pp. 200-203; Price et al. 2011, p. VI-1; TDEC 2014, pp. 51-53). Industrial development and coal mining activities prior to the passage of the Clean Water Act (CWA) of 1972 and the Surface Mining Control and Reclamation Act (SMCRA) of 1977 have left a legacy of contaminated sediment and polluted waters that continues to affect streams in portions of the upper Tennessee River drainage (Hampson 2000, p. 19). Organic compounds are synthetic chemicals that can accumulate in sediments and pose health threats to aquatic wildlife and humans. Most of these chemicals were produced as part of industrial activities carried out many decades earlier, but the chemicals tend to persist in the environment for many years. The most widespread contaminants are PCBs (poly-chlorinated biphenyls) and mercury, originating mostly from industrial activities

Draft Sickle Darter SSA 22 during the 1950s to early 1970s. In 1908, a paper mill near Canton, North Carolina began discharging wastewater containing dioxin and other pollutants into the Pigeon River, affecting downstream reaches in both North Carolina and Tennessee. These releases continued until plant improvements were instituted in the 1990s (Hampson 2000, p. 19). The upper Tennessee River drainage has a long history (1950s to present) of large chemical spills or releases that have devastated biological communities downstream of the release (Carriker 1980, pp. 25, 35-36; Hampson et al. 2000, p. 22; Jones et al. 2001, p. 20; Ahlstedt et al. 2016, pp. 8-9; Hyde and Jones 2019, pp. 2-4). The majority of these events have involved black-water releases from coal preparation plants and slurry impoundments in the Clinch and Powell river systems (Ahlstedt et al. 2016 , pp. 8-9). Releases were severe enough in the early 1980s that both rivers were said to “occasionally run black” with coal fines (Johnson et al. 2012, p. 84). Polycyclic aromatic hydrocarbons (PAHs) are commonly detected as pollutants in soils and sediments of the Clinch and Powell river systems, reflecting the presence of coal fines from upstream mining activities (Hampson et al. 2000, p. 19).

Coal mining activity has decreased in the Clinch and Powell River systems in recent years; however, current and previous mining activities continue to impact portions of these stream systems in Tennessee and Virginia (TDEC 2014, p. 51; Ahlstedt et al. 2016, pp. 13-14; Zipper et al. 2016, pp. 604-612; TDEC 2017, pp. 94-97). Mined watersheds have the potential to contribute high concentrations of dissolved metals and other dissolved solids to downstream stream reaches that can lower stream pH or lead to elevated levels of stream conductivity (a measure of electrical conductance in the water column that increases as the concentration of dissolved solids increases), alkalinity, hardness, and sulfate (Pond 2004, pp. 6-7; Black et al. 2013, pp. 35–46; Zipper et al. 2016, p. 604). Conductivity is often used as a surrogate of disturbance in mined watersheds, where baseline conductivity values tend to be low (< 100 µS/cm). These conditions have been shown to negatively impact biological communities, including losses of mayfly and caddisfly taxa (Chambers and Messinger 2001, pp. 34–51, Pond 2004, pp. 6–7; Hartman et al. 2005, p. 95; Pond et al. 2008, pp. 721–723; Pond 2010, pp. 189– 198) and decreases in fish diversity (Kuehne 1962, pp. 608–614; Branson and Batch 1972, pp. 507–512; Branson and Batch 1974, pp. 81–83; Stauffer and Ferreri 2002, pp. 11–21; Fulk et al. 2003, pp. 55–64; Mattingly et al. 2005, pp. 59–62; Thomas 2008, pp. 1–9; USFWS 2010, pp. 1– 4, Black et al. 2013, pp. 34–45; Hitt 2014, pp. 11–13; Hitt and Chambers 2014, pp. 919–924). The direct effect of these pollutants on fishes, including the Sickle Darter, is poorly understood, but other Appalachian species, such as Blackside Dace (Chrosomus cumberlandensis) and Kentucky Arrow Darter (Etheostoma spilotum), have shown declines in abundance over time as conductivity levels increased in streams affected by mining (Hitt 2014, pp. 11-13; Hitt et al. 2016, pp. 46-52). It is unclear if Sickle Darters are adversely affected by dissolved solids associated with elevated conductivity, but these pollutants have adversely affected fish communities in the Cumberland Plateau region of Kentucky and Tennessee.

Price et al. (2011, p. V-5) reported that concentrations of total dissolved solids have continued to rise in the Powell and Clinch river systems, with rapid increases in headwaters of the Powell River, where coal mining is most prominent. Price et al. (2014, pp. 845-846) and Zipper et al. (2016, pp. 608-609) found a temporal increase of dissolved solids in the Clinch and Powell Rivers between 1964 and 2010 that corresponds to declining mussel densities in the Virginia portions of each river. In addition, water-column ammonia and sediment metals have been

Draft Sickle Darter SSA 23 detected at levels that are likely contributing to the decline of freshwater mussels (and fishes) in the Virginia portions of each river system (Price et al. 2014, pp. 845-846). The increased levels of ammonia, metals, and dissolved solids were observed in watersheds with both agricultural activity and coal mining; however, mussel declines were greater in close proximity to and downstream of watersheds impacted by coal mining (Powell River and Guest River, a tributary to the Clinch River) (Price et al. 2014, pp. 853-855).

Insecticides, herbicides, and fungicides are widely used in the upper Tennessee River drainage to control insects, fungi, weeds, and other undesirable organisms (Hampson 2000, pp. 14-18). The compounds vary in their toxicity, persistence in the environment, and transport characteristics. The federal government banned the use of some of the more persistent organochlorine pesticides, such as DDT and chlordane, but these compounds continue to be detected in the environment. Although pesticides usually are applied to specific areas and directed at specific organisms, these compounds often become widely distributed in the environment and can pose hazards to non- target organisms such as the Sickle Darter.

Impoundments – Habitat Fragmentation and Loss

Impoundments are often cited as a threat to the Sickle Darter and a major factor influencing the species’ current distribution within the upper Tennessee River drainage (Etnier and Starnes 1993, p. 576; Jenkins and Burkhead 1993, pp. 101-106; Service 2020, p. 3). From 1912 to 1963, TVA constructed a total of 12 dams, impounding waters in each of the Sickle Darter’s historical tributary systems in Tennessee and Virginia (Miller and Reidinger 1998, pp. 35-37) (Figure 8, Table 3). Two dams, Watts Bar (constructed in 1942) and Fort Loudoun (constructed in 1943), were constructed on the Tennessee River mainstem, while the remaining 10 dams were built on tributaries – Clinch River, French Broad River, Holston River, South Fork Holston River, and Watauga River. Tributary impoundments include Melton Hill Reservoir (created in 1963), Norris Reservoir (1936), Douglas Reservoir (1943), Cherokee Reservoir (1941), John Sevier Detention Reservoir (1963), Fort Patrick Henry Reservoir (1953), Boone Reservoir (1952), South Holston Reservoir (1950), Wilbur Reservoir (1912), and Watauga Reservoir (1948). Physical, chemical, and biological changes to these systems have been dramatic, and connectivity of populations within these systems has been diminished and in some cases eliminated.

Impoundments cause dramatic changes in riverine habitats, including loss of riffle and shoal habitats; alteration of water flow, leading to increased sedimentation, nutrients, energy inputs, and outputs; increased sediment deposition; modification of flood pulses; increased water depths; decreased levels of habitat heterogeneity; reductions in bottom stability due to subsequent sedimentation; and creation of fish dispersal and migration barriers (Layzer et al. 1993, pp. 68- 69; Neves et al. 1997, pp. 63-64; Watters 1999, pp. 261-262). Dams can also seriously alter downstream water quality and riverine habitat and negatively impact fishes in tailwater habitats (areas immediately downstream of the dam) (Freeman et al. 2001, p. 183; Power et al. 1996, p. 893). These impacts include changes and fluctuation in flow regime, channel scouring, and bank erosion; reduced dissolved oxygen levels and water temperatures; and changes in resident fish

Draft Sickle Darter SSA 24 Table 3. Summary of TVA reservoirs affecting stream systems in the Sickle Darter’s historical range (reservoirs listed in upstream order by watershed).

Completion Impounded Sickle Length TVA Reservoir Date Dam Location Darter Habitats (km/mi) Clinch River, 32 / 20 Watts Bar Reservoir 1942 Tennessee River Emory River 19 / 12 Fort Loudoun 1943 Tennessee River Little River 11 / 7 Reservoir Melton Hill 1963 Clinch River Clinch River 92 / 57 Reservoir Clinch River, 118 / 73 Norris Reservoir 1936 Clinch River Powell River 90 / 56 French Broad Douglas Reservoir 1943 French Broad River 119 / 74 River

Cherokee Reservoir 1941 Holston River Holston River 95 / 59

John Sevier 1954 Holston River Holston River 16 / 10 Detention Reservoir Fort Patrick Henry South Fork South Fork Holston 1953 17 / 10 Reservoir Holston River River South Fork South Fork Holston 27 / 17 Boone Reservoir 1952 Holston River River, Watauga River 24 / 15 South Holston South Fork South Fork Holston 1950 39 / 24 Reservoir Holston River River

Wilbur Reservoir 1912 Watauga River Watauga River 5 / 3

Watauga Reservoir 1948 Watauga River Watauga River 26 / 16 assemblages (Williams et al. 1993, p. 7; Layzer et al. 1993, p. 69; Neves et al. 1997, pp. 63–64; Watters 1999, pp. 265–266).

Reduced Range

The Sickle Darter has a limited geographic range. The existing populations are localized, and geographically isolated from one another due to impoundments and other habitat degradation, leaving them vulnerable to localized extinctions from intentional or accidental toxic chemical spills, habitat modification, progressive degradation from runoff (non-point source pollutants), natural catastrophic changes to their habitat (e.g., flood scour, drought), other stochastic disturbances, and decreased fitness from reduced genetic diversity. Potential sources of unintentional spills include accidents involving trains or motor vehicles transporting chemicals over railroad or road crossings of streams inhabited by the Sickle Darter, or the accidental or intentional release of chemicals used in agricultural or residential applications into streams.

Draft Sickle Darter SSA 25

Figure 8. Reservoirs within the Sickle Darter’s historical range in North Carolina, Tennessee, and Virginia.

Draft Sickle Darter SSA 26 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). Some small Sickle Darter populations (e.g., Middle Fork Holston River) may be 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 unnatural level of isolation of the Sickle Darter makes repopulation following localized extirpations virtually impossible without human intervention.

Climate Change

In its Fifth Assessment Report, 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 48896, August 12, 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 Sickle Darter to random catastrophic events (McLaughlin et al. 2002, pp. 6060–6074; Thomas et al. 2004, pp. 145–148). The species’ early spawning period (February-March) make it vulnerable to warming temperatures and higher flows – conditions that could interrupt or prevent successful spawning in a given year (Service 2020, p. 3). 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 (range shifts, migration of new predators) (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). Stream temperatures in the Southeast have increased roughly 0.2–0.4oC (0.4– 0.7oF) 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 (Kaushal et al. 2010, p. 465).

Estimates of the effects of climate change using available climate models typically lack the geographic precision needed to predict the magnitude of effects at a scale small enough to apply to the range of a given species. However, data on recent trends and predicted changes for the upper Tennessee River drainage (Alder and Hostetler 2016, entire) provide some insight for

Draft Sickle Darter SSA 27 evaluating the potential impacts of climate change to the Sickle Darter. Alder and Hostetler (2017, entire) use different emission scenarios to calculate estimates of average annual increases in maximum and minimum temperature, precipitation, snowfall, and other variables. These scenarios, called “representative concentration pathways” (RCPs) are plausible pathways toward reaching a target radiative forcing (the change in energy in the atmosphere due to greenhouse gases) by the year 2100 (Moss et al. 2010, p. 752). Depending on the chosen model and emission scenario (RCP 8.5 (high) vs. 4.5 (moderate)), annual mean maximum temperatures for the upper Tennessee River drainage are expected to increase by 2.1 to 3.1oC (3.8 to 5.6oF) by 2074, while precipitation models predict that the upper Tennessee River drainage will experience a slight increase in annual mean precipitation (0.5 cm/month (0.2 in/month)) through 2074 (Girvetz et al. 2009, pp. 1–19; Alder and Hostetler 2016, pp. 1–9).

The upper thermal limits of the Sickle Darter are unknown, but the species’ occurrence in multiple stream sizes (large creeks to medium-size rivers) suggests that it may have some tolerance to warmer water conditions. For similar reasons, we also assume the species may be less vulnerable to droughts, compared to species occurring in lower order or headwater streams. Consequently, the effects of climate change on species’ viability are largely unknown, but limited information suggests the species may have some resilience to the effects of climate change. A “Climate Change Vulnerability Assessment” of more than 700 species in the Appalachian region ranked six other darter species in the genus Percina as “moderately vulnerable” to the effects of climate change (Appalachian Landscape Conservation Cooperative 2017). Moderately vulnerable was defined as “abundance and/or range extent within geographical area assessed likely to decrease by 2050.” The Sickle Darter may have some of the same vulnerabilities due to its similar ecology, life history, and small range.

Conservation Actions

State Listings

The Sickle Darter has been state-listed as Threatened in Tennessee (Tennessee Wildlife Resources Commission (TWRC) 2016, p. 3) and Virginia (VDGIF 2018, p. 1). Under the Tennessee Nongame and Endangered or Threatened Wildlife Species Conservation Act of 1974 (Tennessee Code Annotated §§ 70-8-101-112), “…it is unlawful for any person in Tennessee to take, attempt to take, possess, transport, export, process, sell or offer for sale or ship nongame wildlife, or for any common or contract carrier knowingly to transport or receive for shipment nongame wildlife.” Further, regulations included in the Tennessee Wildlife Resources Commission Proclamation 00-15 Endangered Or Threatened Species state the following: except as provided for in Tennessee Code Annotated, Section 70-8-106 (d) and (e), it shall be unlawful for any person to take, harass, or destroy wildlife listed as threatened or endangered or otherwise to violate terms of Section 70-8-105 (c) or to destroy knowingly the habitat of such species without due consideration of alternatives for the welfare of the species listed in (1) of this proclamation, or (2) the United States list of Endangered fauna. Potential collectors of this species would be required to have a state collection permit." In Virginia, the taking, transportation, possession, sale, or offer for sale of any fish or wildlife appearing on any list of threatened or endangered species published by the United States Secretary of the Interior pursuant to the provisions of the federal Endangered Species Act of 1973 (P.L. 93-205), or any

Draft Sickle Darter SSA 28 modifications or amendments thereto, is prohibited except as provided in § 29.1-568 (Virginia Code §§ 29.1-103 and 29.1-501 (2014)).

State Wildlife Action Plans

The Sickle Darter is identified as a Species of Greatest Conservation Need (SGCN) in the Tennessee and Virginia state wildlife action plans (TWRA 2015, p. 48; VDGIF 2015 (Appendix A), p. 89). A SGCN is a species that is at-risk, threatened, or deserving of conservation action for other reasons. Tennessee’s first comprehensive wildlife strategy was revised for the first time in 2015 (TWRA 2015, entire). Key attributes of the revised plan include an expansion of statewide mapping efforts to include priority problems affecting habitats; the identification of conservation opportunity areas; integration of climate change vulnerability assessments; the revision of Tennessee’s SGCN list, including the addition of plants (as Tier 4); and the targeting of priority conservation actions with both government agency and non-governmental organization partners. Species of Greatest Conservation Need.

The Virginia wildlife action plan identifies the Sickle Darter as a Tier 1c species (critical conservation need) (VDGIF 2015 (Appendix A), p. 89 ). In the Virginia plan, a Tier 1 species is considered to face an extremely high risk of extinction or extirpation. Populations of these species are at critically low levels, face immediate threat(s), and/ or occur within an extremely limited range. Intense and immediate management action is needed. A category of “c” means that managers have failed to identify “on the ground” actions or research needs that could benefit this species or its habitat, or all identified conservation opportunities for a species have been exhausted. The plan describes Sickle Darter habitats as “flowing pools over rocky, sandy, or silty substrates in clear creeks or small rivers.”

Existing Regulatory Mechanisms

The Sickle Darter and its habitats are afforded some protection from water quality and habitat degradation under the Clean Water Act, SMCRA, Tennessee’s Nongame and Endangered or Threatened Wildlife Species Conservation Act of 1974, Tennessee’s Water Quality Control Act of 1977 (T.C.A. 69–3–101), Virginia’s State Water Control Act (Virginia Code § 62.1-44), and additional Tennessee and Virginia statutes and regulations regarding natural resources and environmental protection. While it is clear that the protections afforded by these statutes and regulations have not prevented the degradation of some habitats used by the Sickle Darter, the species has undoubtedly benefited from improvements in water quality and habitat conditions stemming from these regulatory mechanisms.

Incidental Protections Provided by the Endangered Species Act

The Sickle Darter receives incidental protection under the Endangered Species Act of 1973 (Act), as amended (16 U.S.C. 1531 et seq.) because populations in portions of the Clinch River, Emory River, Little River, Holston River, and Sequatchie River share habitats with multiple federally listed fishes and mussels (see Appendix A, Table 9). Some of these species include Cumberlandian Combshell (Epioblasma brevidens), Dromedary Pearlymussel (Dromus dromas), Fanshell (Cyprogenia stegaria), Fluted Kidneyshell (Ptychobranchus subtentum), Littlewing

Draft Sickle Darter SSA 29 Pearlymussel (Pegias fabula), Oyster Mussel (Epioblasma capsaeformis), Rough Pigtoe (Pleurobema plenum), Spectaclecase (Cumberlandia monodonta), Spotfin Chub (Erimonax monachus), and Duskytail Darter (Etheostoma percnurum). Section 7 of the Act requires Federal agencies to consult with the Service on any action that may affect a listed species or any action that may destroy or adversely modify critical habitat. Section 9 of the Act also provides protection against “take” of the species (“take” means to harass, harm, pursue, hunt, shoot, wound, kill, trap, capture, or collect or attempt to engage in any such conduct).

Propagation Efforts

CFI (Knoxville, Tennessee) initiated propagation efforts for the Sickle Darter in 2015 (Petty et al. 2017, pp. 2-6). CFI personnel collected adult broodstock (females and males) from the Little River, Blount County, Tennessee, during July 2015 (6 adults), July and September 2016 (12), July 2017 (2), July and August 2018 (14), and October 2019 (3) (Ruble 2019, pers. comm.). CFI has had limited success with syncing of males and females in captivity, but a total of 25 juvenile Sickle Darters (40-50 mm TL) were produced and released into the Tellico River at Nars Ford, Monroe County, in June 2017. We question the rationale of stocking these individuals in a stream located outside of the species’ historical range, but the propagation effort has provided valuable information on the species’ reproduction and early life history. The current status of the individuals released into the Tellico River is unknown.

Draft Sickle Darter SSA 30 CHAPTER 4. CURRENT CONDITION AND SPECIES VIABILITY

Methodology

In this chapter, we assess and describe the current condition and viability of the Sickle Darter. Each population is described separately with respect to collection history, species abundance, habitat conditions, and specific stressors. Current population resiliency is then assessed for each population using habitat and population metrics (described below), followed by a summary of range-wide redundancy and representation.

To complete our analysis, we used the best available information, including peer reviewed scientific literature, academic reports, and survey data provided by State agencies and academic institutions. Fundamental to our analysis of the Sickle Darter was the determination of analytical units (i.e., populations) at a scale useful for assessing the species. We divided the Sickle Darter’s range into 10 analytical units (populations): Emory River, Clinch River, Powell River, Little River, French Broad River, North Fork Holston River, Middle Fork Holston River, South Fork Holston river, Watauga River, and Sequatchie River (Figure 7). Information on population genetics and movement behavior is lacking for the Sickle Darter; however, we proposed these divisions based on our knowledge of the species’ current and historical distribution within the upper Tennessee River drainage and the level of current geographic isolation observed among tributary systems. The 10 populations are separated from each other by long distances, and they have been further isolated by the construction of several impoundments on the Tennessee River mainstem and its tributaries.

To qualitatively assess current viability, we considered six components that broadly relate to the species’ physical environment (“Habitat Elements”) or its demography (“Population Elements”). Each population’s physical environment was assessed by averaging three components describing physical habitat quality, connectivity, and water quality. Components describing population demography included reproduction, occurrence extent (total length of occupied streams compared to historical range), and occupied stream length. Parameters for each component’s condition category were established by evaluating the range of existing data and separating those data into “High” condition (H), “Moderate” condition (M), “Low” condition (L), or “Zero” (0) based on our understanding of the species’ demographics and habitat (Table 4). Using the demographic and habitat parameters defined in Table 4, we categorized each population as being in “High” condition (H), “Moderate” condition (M), “Low” condition (L), or “presumed extirpated” (0). To aid in the comparison of populations (with each other and under the future scenarios outlined in Chapter 5) and the assessment of the species’ current viability using the 3Rs, we weighted each of the six components equally and determined the average score to describe each population’s current condition.

Draft Sickle Darter SSA 31 Table 4. Component conditions used to assess current condition for populations of the Sickle Darter.

Condition Component High Moderate Low 0 Physical Habitat Slow-flowing pools Slow-flowing pools Slow-flowing pools Habitat unsuitable abundant (ample cover present but not scarce (few pools (species absent) in pools); silt abundant (some pools with cover); silt deposition low; no with cover);silt deposition extensive or deposition moderate; extensive; habitats significant habitat habitat alterations at severely altered and alterations (e.g. recent moderate levels- recognized as channelization, channelization or other impacting the riparian clearing); habitat disturbance species; <25% of >75% of available more widespread; 25- habitats suitable for habitat suitable for the 75% of available the species species habitat suitable for the species Connectivity High immigration Moderate immigration Low immigration No connectivity potential between potential between potential between (populations populations (no dams populations populations isolated; no or other barriers (populations separated (populations immigration separating by a low-head dam) separated by ≥2 potential due to the populations) low-head dams or presence of large other barriers) reservoirs)

Water Quality Minimal or no known WQ issues recognized WQ issues prevalent Habitat unsuitable water quality (WQ) and may impact within system, likely (species absent) issues (i.e., no 303(d) species (i.e., some impacting streams impacting the 303(d) streams, populations (i.e., species, area sparsely unpaved roads more numerous 303(d) populated, few roads) common, moderate streams) housing amounts)

Reproduction Species persisting over Species persisting over Species persisting Extirpated time; clear evidence of time; clear evidence of over time but no reproduction (multiple reproduction direct evidence of age classes present) (juveniles present) reproduction (only adults present) Occurrence Extent <10% decline from 10-50% decline from >50% decline in Extirpated known range known range known range

Occupied Stream ≥ 22.5 km (≥ 14 mi) 11.3–22.5 km (7–14 < 11.3 km (< 7 mi) Extirpated Length (Continuity) mi)

Draft Sickle Darter SSA 32 Habitat Elements

Physical Habitat Quality

Sickle Darters are typically observed in slow flowing pools, glides, or runs (mean velocities of 6- 7 cm/s (0.20-0.23 ft/s)) of large, upland creeks and small to medium rivers with good water quality, clean sand-detritus or gravel-cobble-boulder substrates, and some type of cover - beds of American Water Willow, submerged aquatic vegetation, or woody debris piles (Etnier 1997, p. 78; Etnier and Starnes 1993, p. 576; Page and Near 2008, p. 609; Alford 2019, p. 8) (Figure 3). Based on field observations by Etnier and Starnes (1993, p. 576) and Alford (2019, pp. 9-10) and discussions with species experts, we evaluated the composition and quality of physical habitat in each population, and the magnitude and scope of potential threats, such as channelization, siltation, or riparian vegetation removal (Table 4).

Connectivity

For the purposes of this SSA, connectivity is a measure of immigration potential in the event of a catastrophic event leading to extirpation. The ability for the species to move upstream and downstream and between tributary systems is also important for feeding, spawning migration, seasonal movements, refuge from extreme high or low water events and predators, and the exchange of genetic material. Connectivity for each river system was evaluated based on the number, type, and location of known barriers (e.g., lock & dams, reservoirs) that could affect the species’ life history needs.

Water Quality

We evaluated water quality by determining how many impacts were identified, their severity, and if measures have been taken toward removing the issues. Tennessee’s and Virginia’s Clean Water Act Section 303(d) and Total Maximum Daily Loads (TMDLs) program reports (TDEC 2017, pp. 12-18, 34-39; VDEQ 2018, pp. 62-66, 89-91), watershed reports by various groups, and input from species experts were used to identify impaired stream reaches and potential pollutants that could be impacting the species.

Population Elements

Collection records were used to evaluate population elements, and these records were compiled from a variety of sources as described in Chapter 2 (Historical Range and Distribution). The dataset used in this analysis is not considered exhaustive but represents the best data accessible in the public domain. Each collection record is referenced with geographic coordinates. Records were considered recent (current) if they had been obtained since 2005 and historical if they represented a collection completed prior to 2005.

Reproduction

Evidence of reproduction and recruitment was indicated by species persistence and the presence of one or more age classes (recorded field measurements of total length). Condition categories

Draft Sickle Darter SSA 33 consisted of high (persistence and multiple age classes), moderate (persistence with only one age class - juveniles), low (persistence with only one age class - adults), and extirpated (no fishes observed).

Occurrence Extent

Occurrence extent for the Sickle Darter was evaluated by comparing the species’ current and historical ranges and determining if the species’ historical range had decreased by < 10 percent (high), 10-50 percent (moderate), or > 50 percent (low). Historical and current records were assessed separately to determine and quantify any range reduction or expansion that may have occurred. As stated previously, the historical range of the Sickle Darter consisted of 10 tributary systems of the upper Tennessee River in North Carolina, Tennessee, and Virginia (Figure 6). Within each tributary system, the historical range was calculated from the furthest upstream collection point within each tributary to its confluence with the nearest downstream river or stream. To determine the current range, we used all records obtained between 2005 and 2019 (Figure 7) and evaluated how those records compared to historical collections.

Occupied Stream Length (Continuity)

Occupied stream length is a measure of the amount of continuously occupied habitat in each population. It was perceived that populations would have a greater degree of genetic exchange and greater resiliency in areas that had a greater continuous length of stream connecting the upstream and downstream extent of the population. The exchange and maintenance of genetic material are critical for the persistence of a population. We expect populations that occupy longer stream reaches to be more resilient against extirpation or extinction (Fagan 2002, p. 3244).

Current Population Status

For the Sickle Darter to exhibit high representation, its populations should exhibit high resiliency and should occur in the ecoregion where they are native (e.g., Blue Ridge Mountains, Ridge and Valley, Southwestern Appalachians); these occupied populations should occur at the widest extent possible across the historical range of the species; and they should occupy multiple tributaries in addition to the core population within the mainstem of a river or stream. Finally, connectivity should be maintained between representative populations because it allows for the exchange of novel and beneficial adaptations where connectivity is high or is the mechanism for localized adaption and variation where connectivity is lower and the species is naturally more isolated. It is helpful to consider representation in terms of how much it is reduced if a population is extirpated.

High redundancy for the Sickle Darter is characterized by having 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 if a population becomes extirpated. Additionally, populations should have a low likelihood of extirpation due to catastrophic events.

Draft Sickle Darter SSA 34

For the Sickle Darter to exhibit high representation, all tributary systems (populations) should have high resilience and occur at a wide extent across the upper Tennessee River drainage where the species is native. Within each population, the species should occupy multiple tributaries in addition to the core population within the mainstem.

High redundancy for the Sickle Darter is characterized by having multiple resilient and representative populations distributed within the species’ ecological setting and across its range. Increased connectivity would further improve redundancy by reinforcing existing populations and increase the likelihood for reestablishment of lost populations. The current condition and status of each population is summarized below.

Emory River

The Sickle Darter’s current distribution within the Emory River system is limited to portions of the mainstem Emory River and one of its tributaries, Rock Creek, in Morgan County, Tennessee (Figure 9) (Alford 2019, pp. 7-9). Surveys completed in 2005, 2008, 2013, 2016, and 2017 produced a total of 49 Sickle Darters from the Emory River and 46 individuals from Rock Creek (TVA, unpublished data; Page and Near 2007, pp. 608-609, 612; Russ 2006, p. 138; Alford 2019, pp. 7-9, 25-28). Russ (2006, p. 138) observed Sickle Darters at 1 of 52 200-m (656-ft) sites sampled throughout the Emory River system during 2004 and 2005. Russ (2006, pp. 93- 144) observed 7 individuals in Rock Creek but did not observe the species in the mainstem Emory River (7 sites), Clear Creek, Daddys Creek, Obed River, or other smaller tributaries. Alford (2019, pp. 6-7) observed Sickle Darters in the mainstem Emory River and Rock Creek, but he did not observe the species in survey reaches located on Clear Creek, Crab Orchard Creek, and White Creek – all Obed River tributaries. Alford (2019, pp. 13-14) considered habitats in Clear Creek and White Creek to be suitable for the Sickle Darter; however, he identified gradient and physiography as potential limiting factors in the Sickle Darter’s dispersal into the Obed River system. Length-frequency distributions prepared by Alford (2019, pp. 8-9) indicated the presence of multiple age classes in the mainstem Emory River and Rock Creek, and successful recruitment was evident based on the presence of young-of-year individuals (<40 mm TL). In the Emory River system, Alford (2019, p. 43) observed Sickle Darters in shallow pools with woody debris or submerged aquatic vegetation, and these habitats were in close proximity to runs or riffles (Figure 3).

Using results of snorkeling surveys by Alford (2019, pp. 24-33), we estimated a population size of 1,400-3,500 Sickle Darters in the Emory River system. Our estimate was based on methods used by Eisenhour et al. (2011, p. 15) to estimate population size for the Longhead Darter in Kinniconick Creek, Kentucky. Our estimate assumed that Alford (2019, pp. 24-33) observed 20- 50 percent of Sickle Darters in each survey reach, and we extrapolated from the total survey reach of 1360 m (0.84 mi) to the occupied reach of 22,600 m (14 mi) to arrive at our estimate.

Streams in the Emory River system continue to be degraded by siltation, loss of riparian vegetation, elevated levels of dissolved solids, and nutrient inputs associated with agriculture, legacy mining, municipal point source discharges, petroleum activities, and development (TDEC 2017, pp. 103-106). These stressors are likely limiting the Sickle Darter’s distribution within the

Draft Sickle Darter SSA 35 system, but the species’ persistence and documented recruitment within the mainstem Emory River and Rock Creek suggest that physical habitat and water quality conditions within these reaches are favorable for the species. We consider habitat conditions in these reaches to correspond to a high condition category for physical habitat and a moderate condition category for water quality as summarized in Table 5. In the remainder of the Emory River system, physical habitat and water quality conditions vary in quality from poor (zero) to moderate. Stressors such as siltation, elevated levels of dissolved solids, and nutrient inputs continue to impact these watersheds, and TDEC (2017, pp. 103-106) has identified several impaired stream reaches within the system, including downstream portions of Emory River (from the confluence with Crab Orchard Creek downstream to Watts Bar Reservoir), Copeland Creek, Crooked Fork, Drowning Creek, Little Obed River, Mud Creek, and Obed River. No impoundments have been constructed within occupied reaches of the mainstem Emory River or Rock Creek, but TDEC (2002, p. 14) identified 47 dams in other portions of the system, with 45 of these occupying the western half of the system in Cumberland and western Morgan counties.

Forest is the dominant land use (71.6 percent) within the Emory River system, with lesser amounts of agriculture (13.8 percent) and developed land (8.3 percent). Public ownership within the system is relatively high, but public ownership along occupied reaches of the mainstem Emory River and Rock Creek is limited to a 2-km (1.2-mi) reach at the confluence of the Emory River and Obed River. This reach, and an additional 70 km (41 mi) of the mainstem Obed River and other tributaries are protected as part of the National Wild and Scenic River System (Obed National and Scenic River) managed by the U.S. Park Service. Public ownership in other portions of the Emory River system includes Frozen Head State Park, a 24,000-acre wilderness area in the headwaters of Crooked Fork in eastern Morgan County, and Catoosa Wildlife Management Area, a 82,000-acre large game-management property in Cumberland, Fentress, and Morgan counties.

The species’ persistence within the system (over 40 years), recent evidence of reproduction and recruitment, and the quality of physical habitat and water quality in the mainstem Emory River and Rock Creek indicate moderate-high levels of resiliency. The species’ resiliency is reduced by its continued exposure to nonpoint source pollutants and its low connectivity. The population is isolated from other Tennessee River tributaries by Watts Bar Reservoir, but no significant barriers are located within the occupied reach. Based on all of these factors, we consider the Emory River population to have a moderate resilience to stochastic events (Table 5).

Draft Sickle Darter SSA 36

Figure 9. Current distribution of the Sickle Darter in the Emory River system, Tennessee, based on fish surveys completed since 2005 (Russ (2006), Alford (2019), and TVA unpublished data).

Draft Sickle Darter SSA 37 Clinch River

The Sickle Darter was reported historically from the mainstem Clinch River, Copper Creek, and Little River in Virginia, but current records from the upper Clinch River system are limited to a single observation (2008) in Copper Creek, Scott County, Virginia (Figure 10) (Etnier and Starnes 1993, pp. 575-577; Jenkins and Burkhead 1994, pp. 791-793; Pinder and Jones 2000; Rakes et al. 2009, p. 4; Alford 2019, p. 12; Service unpublished data). The species appears to be extirpated from the mainstem Clinch River and Little River.

Streams in the upper Clinch River system continue to be degraded by pathogens, siltation, elevated levels of dissolved solids, and nutrient inputs (Jenkins and Burkhead 1994, pp. 92-95; Price et al. 2014, pp. 849-855; TDEC 2014, p. 51; Ahlstedt et al. 2016, pp. 13-14; Zipper et al. 2016, pp. 604-612; TDEC 2017, pp. 94-96; VDEQ 2018 (Appendix 5), pp. 2380-2394, 2402- 2416). The primary sources of impairment include agricultural practices (pasture grazing and unrestricted cattle access), legacy coal mining, municipal point source discharges, and residential development. The upper Clinch River system (Tennessee and Virginia) continues to support populations of 15 federally endangered mussels (Appendix A); however, mussel density and richness in the Virginia portion of the mainstem Clinch River has declined significantly over the last 30 years and much of this decline is attributed to anthropogenic disturbance (e.g., chemical releases and spills) (Ahlstedt et al. 2016, pp. 11-14). The Sickle Darter’s persistence within lower reaches of Copper Creek suggests that physical habitat and water quality conditions within these reaches have been sufficient for the species to persist in low densities; however, the species has not been observed since 2008 and these reaches continue to be affected by the same stressors identified previously. Connectivity within the upper Clinch River system is reduced due to the creation of two reservoirs: Melton Hill Reservoir and Norris Reservoir (Table 3, Figure 8). These reservoirs have resulted in the inundation of 134 km (83 mi) of the mainstem Clinch River in Tennessee. This has affected seasonal fish movements within the mainstem Clinch River and essentially halted intertributary movements between the Clinch and Powell Rivers. Impoundments are lacking upstream of Norris Reservoir, allowing fishes to move freely within the system.

Based on the species’ low density within the system and continued habitat degradation and water quality impairment associated with agriculture, legacy coal mining, and development, we consider the upper Clinch River population to have a low resilience to stochastic events (Table 5). Several resiliency measures (e.g., physical habitat, water quality, and connectivity) indicate a low-moderate level of resiliency, but the low number of observations over the past 15 years and the species’ restricted distribution (occurrence extent) and relatively short, occupied reach is more indicative of a low level of resiliency to stochastic events. Considering all these factors, we arrived at an overall resiliency estimate of low.

Draft Sickle Darter SSA 38

Figure 10. Current distribution of the Sickle Darter in the Clinch River and Powell River systems, Tennessee and Virginia, based on fish surveys completed since 2005 (Alford (2019), CFI and TVA unpublished data).

Draft Sickle Darter SSA 39 Powell River

The species has not been observed in the Powell River system since 1893 and is now considered to be extirpated (Figure 10) (Alford 2019, p. 12; Service unpublished data). Alford (2019, p. 12) surveyed the species’ only historical location (Indian Creek, Claiborne County, Tennessee) and an adjacent reach of the mainstem Powell River, but no Sickle Darters were observed. Alford (2019, p. 13) considered physical habitat conditions in the Powell River to be favorable for the species, but the species has not been observed in the system for over 120 years.

Suitable habitat conditions for the Sickle Darter may occur in limited reaches within the Powell River system, but we consider overall physical habitat conditions and water quality to be of moderate quality. The Powell River system continues to be threatened by siltation, nutrients, pathogens, dissolved solids (elevated conductivity and hardness), and untreated wastewater discharges (Johnson et al. 2012, pp. 87-89; Zipper et al. 2016, pp. 609-613; TDEC 2017, pp. 96- 97; VDEQ 2018 (Appendix 5), pp. 2450-2480). Identified sources of impairment include agriculture (unrestricted cattle access, pasture/grazing, animal feeding operations), municipal point source discharges, coal mining, natural gas extraction, land development (urbanized areas), and highway/road runoff. Many of these stressors have been suspected as the cause of mussel declines in the mainstem Powell River (Johnson et al. (2012, pp. 87-89; Ahlstedt et al. 2016, pp. 11-14). Surface coal mining has caused dramatic landscape changes in headwater reaches of the Powell River in Lee and Wise Counties, Virginia, leading to increasing levels of dissolved solids and associated constituents (conductivity, pH, hardness, sulfates) in receiving streams (Zipper et al. 2016, pp. 609-613). These conditions have likely contributed to mussel declines in downstream reaches of the mainstem Powell River, but potential effects on the fish community are unknown. Norris Reservoir restricts fish passage between the Powell and Clinch Rivers, but connectivity is high in upstream reaches of the Powell River.

Due to the species’ 126-year absence from the system and continued threats to physical habitat and water quality from agriculture and other pollutant sources, the Powell River population is considered to be extirpated (Table 5).

Little River

The Sickle Darter was first recorded from the Little River, Blount County, Tennessee, in October 1969 (TDEC; Etnier Ichthyological Collection, University of Tennessee). Since that time, repeated survey efforts by agency biologists, academics, and conservation groups have observed the species at multiple sites within the mainstem Little River (Figure 11) (Heacock 1995, pp. 34- 40; Jett 2010, pp. 22-27; Petty et al. 2017, p.8; Alford 2019, pp. 8-9; Service unpublished data). At present, the species appears to occupy an approximate 22-km (14-mi) reach of the Little River, extending from the Peery’s Mill Dam site at Melrose (rkm 35 (rmi 22)) downstream to the Tennessee Route 33 bridge crossing (rkm 13 (rmi 8) (Petty et al. 2017, pp. 5-6; Service unpublished data). Recent surveys by Petty et al. (2017, p. 8) and Alford (2019, pp. 8-9) demonstrate that the Little River population is represented by multiple age classes, and successful recruitment is evident based on the presence of young-of-year individuals (<40 mm TL). Alford (2019, p. 44) observed Sickle Darters in shallow pools along the bank with beds of Water Willow and in close proximity to areas of current (Figure 3).

Draft Sickle Darter SSA 40

Using results of snorkeling surveys by Alford (2019, pp. 24-33), we estimated a population size of 420-1,050 Sickle Darters in the Little River system. Our estimate was based on methods used by Eisenhour et al. (2011, p. 15) to estimate population size for the Longhead Darter in Kinniconick Creek, Kentucky. Our estimate assumed that Alford (2019, pp. 24-33) observed 20- 50 percent of Sickle Darters in each survey reach, and we extrapolated from the total survey reach of 6,095 m (3.8 mi) to the occupied reach of 24,000 m (15 mi) to arrive at our estimate.

The Little River is a fifth order tributary of the Tennessee River in Blount, Knox, and Sevier counties, Tennessee. The headwaters originate on the north slope of Clingman’s Dome in Great Smoky Mountains National Park, Sevier County, and approximately one-third of the watershed lies within the park boundary. Outside of the park, the Little River flows northwest through Blount and Knox counties, eventually emptying into the Tennessee River (Fort Loudoun Reservoir) in Knoxville. Water quality and habitat conditions in headwater reaches have been described as excellent (Jett 2010,p. 3), but downstream of Great Smoky Mountains National Park, stream habitat and water quality are influenced by a variety of pollutants originating from agricultural, municipal, and residential sources (Layman 1991, p. 483; Petty et al. 2017, p. 2). Degradation of physical habitat and water quality has been most severe in tributaries (e.g., Crooked Creek, Ellejoy Creek, and Rocky Branch), which continue to be affected by siltation, nutrients (nitrate/nitrite, phosphorus), loss of riparian vegetation, stream habitat alteration, and pathogens (TDEC 2017, pp. 84-87). Downstream reaches of the mainstem Little River are affected by these same pollutants, but the species’ persistence and documented recruitment in the Little River suggest that the magnitude and scope of these threats is reduced in the mainstem and physical habitat and water quality conditions are favorable for the species. Physical habitat and water quality within the mainstem Little River is further evidenced by the continued presence of federally listed species such as the Duskytail Darter and Snail Darter (Percina tanasi) (Layman 1991, p. 483) (Table 10, Appendix A). We consider overall physical habitat and water quality in these reaches to be of moderate-high quality (Table 5). Connectivity for the Little River system is zero due to the presence of a low head dam at the Rockford Manufacturing Company site in Rockford (rkm 11 (rmi 7)), Fort Loudoun Dam southwest of Knoxville, and Peery’s Mill dam near Melrose (rkm 35 (rmi 22)) (Figure 10). The low-head dam at Rockford and backwaters of Fort Loudoun Reservoir create impounded conditions in downstream reaches of the mainstem Little River that restrict the species’ movement. Peery’s Mill dam is also a movement barrier, preventing the Sickle Darter from utilizing suitable habitats upstream of the mill dam site (Alford 2019, p. 12).

Draft Sickle Darter SSA 41

Figure 11. Current distribution of the Sickle Darter in the Little River system, Tennessee, based on fish surveys completed since 2005 (Alford (2019), CFI and TVA unpublished data).

Draft Sickle Darter SSA 42

We consider the Little River population to have a moderate resilience to stochastic events (Table 5). Several resiliency measures (e.g., physical habitat, water quality, reproduction occurrence extent, occupied stream length) indicate a moderate-high level of resiliency for the Little River population, but the species is separated from other Sickle Darter populations by Fort Loudoun Reservoir (connectivity is zero), and two smaller dams, Rockford and Peery’s Mill, limit the species’ distribution within the mainstem Little River. Considering all these factors, we arrived at an overall resiliency estimate of moderate.

French Broad River

The only record of the Sickle Darter from the upper French Broad River system in North Carolina was recorded in 1940 near Skyland, Buncombe County, North Carolina (Menhinick et al. 1974, p. 42; Etnier 1997, p. 78). Since 1940, extensive surveys of the French Broad River by TVA biologists and other investigators have produced no additional specimens from the system (Figure 12). Cooper et al. (1977, p. 287) and Etnier (1997, p. 78) considered the species to be extirpated from North Carolina, listing deterioration of water quality in the French Broad River as the primary reason for the species’ decline. The Sickle Darter was also recorded historically from two sites in the Little Pigeon River system (Walden Creek and West Prong Little Pigeon River), but it has not been observed in that system since 1979. Alford (2019, p. 13) considered habitat conditions to be favorable for the species in Walden Creek and West Prong Little Pigeon River (Little Pigeon River system), but portions of the system continue to be affected by siltation, elevated nutrients, pathogens, elevated stream temperatures, and riparian disturbance (TDEC 2017, pp. 69-72). Physical habitat and water quality conditions in the mainstem French Broad River in North Carolina have improved over the last two decades, and habitat conditions in some reaches now appear to be suitable for the species (Service 2020, entire). Douglas Reservoir restricts fish passage between upper and lower reaches of the mainstem French Broad River and adjacent tributaries, so connectivity is considered to be zero. Due to the Sickle Darter’s absence from the system for 40 years and its continued isolation from other Sickle Darter populations (zero connectivity), the French Broad River population is considered to be Extirpated (Table 5).

Draft Sickle Darter SSA 43

Figure 12. Current distribution of the Sickle Darter in the French Broad River system, Tennessee and North Carolina, based on fish surveys completed since 2005 (Alford (2019) and TVA unpublished data).

Draft Sickle Darter SSA 44 North Fork Holston River

Based on surveys completed since 2005, the Sickle Darter occupies a 34-km (21-mi) reach of the mainstem North Fork Holston River upstream of Saltville in Smyth County, Virginia (Figure 13) (Alford 2019, p. 12; Service unpublished data). A total of three individuals have been observed within this reach over the last 15 years (Alford 2019, p. 12; Service unpublished data). The species has not been observed at historical sites located downstream in Scott and Washington counties, Virginia, since the 1970s (Feeman 1980, pp. 17-27; Feeman 1986, pp. 5-8; Hill et al. 1989, pp. 61-70; Alford 2019, p. 12; Service unpublished data).

The North Fork Holston River in Tennessee and Virginia has a long history of anthropogenic disturbance. Habitat degradation was chronic and extensive by the 1920s (i.e., heavy releases of dissolved solids from the Olin Corporation chlor-akali plant located in Saltville, Virginia), and significant pollution events (e.g., chemical releases – sodium and chloride wastes) continued through the 1950s and 1960s (Feeman 1986, pp. 8-9; Jenkins and Burkhead 1994, pp. 92-93). The fish fauna has recovered steadily since the early 1970s (Hill et al. 1989, pp. 61-70; Jenkins and Burkhead, p. 92), but fish samples collected downstream of Saltville continue to show high levels of mercury, and the system continues to be affected by other activities and pollutants, such as siltation, pathogens, nutrients, and instream habitat disturbance associated with agriculture (unrestricted cattle access), rural residential land use, untreated wastewater discharges, and coal mining (Feeman 1986, p. 9; TDEC 2017, pp. 62-67; VDEQ 2018, pp. 89-91, (Appendix 5, pp. 2352-2359)). Alford (2019, p. 12) completed qualitative habitat evaluations at several sites on the mainstem North Fork Holston River. He concluded that these sites appeared to be unsuitable for the Sickle Darter because stream reaches lacked pools with appropriate depths (40-50 cm (16-20 in)), pools did not contain substrates with the right particle composition (mixtures of silt, sand, gravel, and cobble), and most available pools lacked cover in the form of woody debris and aquatic vegetation. The North Fork Holston River is isolated from other Tennessee River tributaries by Cherokee Reservoir.

We consider the North Fork Holston River population to have a low resilience to stochastic events (Table 5). With the exception of occupied stream length, habitat and population element scores generally indicate low levels of resiliency.

Middle Fork Holston River

The Sickle Darter continues to occupy the mainstem Middle Fork Holston River near Chilhowie, Smyth County, Virginia, but the species has not been observed at downstream historical sites in Washington County since the 1930s (Figure 13) (Feeman 1980, pp. 17-27; Alford 2019, pp. 6-7, 11-12; Service unpublished data). Alford (2019, p. 6-7) observed Sickle Darters (total of five adult specimens) at two of three survey sites visited near Chilhowie in 2018. Sickle Darters were observed under fallen woody debris in shallow pools situated along the bank, and these habitats were adjacent to faster current (Alford 2019, p. 45) (Figure 3).

Draft Sickle Darter SSA 45

Figure 13. Current distribution of the Sickle Darter in the upper Holston River system (North Fork Holston River, Middle Fork Holston River, South Fork Holston River, Watauga River) in Tennessee and Virginia, based on fish surveys completed since 2005 (Alford (2019) and TVA unpublished data).

Draft Sickle Darter SSA 46

The mainstem Middle Fork Holston River near Chilhowie contains habitat suitable for the Sickle Darter, but the system continues to be threatened by siltation, pathogens, nutrients, and other chemicals associated with agriculture (unrestricted cattle access, pasture), rural residential land use, untreated wastewater discharges, and highway/road runoff (VDEQ 2018, pp. 89-91). Due to these stressors, downstream reaches of the mainstem Middle Fork Holston River and numerous tributaries (e.g., Greenway Creek, Hall Creek) have been added to Virginia’s 303(d) list of impaired waters (water is not meeting the Aquatic Life use designation) (VDEQ 2018, pp. 53-55, 89-91, (Appendix 5, pp. 2313-2378)). Connectivity in upstream reaches of the Middle Fork is high (no barriers to fish movement), but South Holston Reservoir impounds the lower reaches of the mainstem Middle Fork Holston River, restricting fish passage between the Middle and South Forks.

We consider the Middle Fork Holston River population to have a low resilience to stochastic events (Table 5). The species has persisted in the mainstem Middle Fork Holston River for over 100 years, but habitat and population elements (physical habitat, water quality, reproduction, occurrence extent, and occupied stream length) indicate low levels of resiliency.

South Fork Holston River

The species’ two historical locations (September 1947) are now inundated by South Holston Reservoir, and the species has not been observed in the South Fork Holston River system since that time (Figure 13) (Service, TDEC, and TVA unpublished data). Multiple tributaries of the South Fork Holston River (e.g., Morrell Creek, Paddle Creek) and the mainstem South Fork Holston River downstream of South Holston Dam have been added to Tennessee’s 303(d) list of impaired waters (water is not meeting the Aquatic Life use designation) due to pollution (i.e., siltation, pathogens, and nutrients) associated with agriculture (pasture grazing), land development, upstream impoundments, and septic discharges (TDEC 2018, pp. 51-58). Connectivity for the South Fork Holston River population is zero due to the creation of Fort Patrick Henry Reservoir, Boone Reservoir, and South Holston Reservoir, restricting movement (immigration) of fishes from other Tennessee River tributaries. Based on the species’ absence from the system for over 70 years, habitat loss caused by the creation of Boone Reservoir and South Holston Reservoir, and continued threats from nonpoint source pollutants, the South Fork Holston River population is considered to be extirpated (Table 5).

Watauga River

The species has not been observed in the Watauga River system since 1984 and is now considered to be extirpated (Figure 13) (Table 5) (Alford 2019, p. 12; Service unpublished data). One historical location (Watauga River, September 1947) is now inundated by Watauga Reservoir. The other historical location (Doe River near Valley Forge, August 1984) remains free-flowing, but the species has not been observed in the Doe River since 1984. Multiple tributaries of the Watauga River (e.g., Gap Creek, Roan Creek) and the mainstem Watauga River downstream of Watauga Dam have been added to Tennessee’s 303(d) list of impaired waters (water is not meeting the Aquatic Life use designation) due to pollution (i.e., sediment,

Draft Sickle Darter SSA 47 pathogens, and nutrients) associated with agriculture (pasture grazing), land development, upstream impoundments, and septic discharges (TDEC 2018, pp. 58-62). The Watauga River population is isolated from other Tennessee River tributaries by Boone Reservoir and Watauga Reservoir.

We consider the Watauga River population to have a low resilience to stochastic events (Table 5). The species has not been observed in the system since 1984, habitats in the system continue to be affected by a variety of pollutants, and the population is isolated from other Sickle Darter populations by two reservoirs.

Sequatchie River

The Sickle Darter was first observed in the Sequatchie River system in 2014 (Figure 14) (Alford 2019, p. 2) – a single individual observed by TVA biologists in the Sequatchie River, Bledsoe County, Tennessee (rkm 137.6 (rmi 85.5)). Alford (2019, p. 7) observed a second Sickle Darter at this location during surveys (2017-2019) on the mainstem (four sampling events). The mainstem Sequatchie River near Pikeville, Bledsoe County, contains suitable habitat for the species, but the system continues to be affected by pollutants (sediment, pathogens, and nutrients) associated with agriculture (pasture grazing), land development, upstream impoundments, and septic discharges (TDEC 2018, pp. 125-128). Based on these stressors, multiple tributaries of the Sequatchie River (e.g., Hall Creek, Swafford Branch) and portions of the mainstem Sequatchie River have been added to Tennessee’s 303(d) list of impaired waters (water is not meeting the Aquatic Life use designation) (TDEC 2018, pp. 125-128). The Sequatchie River is isolated from other Tennessee River tributaries by Guntersville, Nickajack, Chickamauga, and Watts Bar reservoirs.

We consider the Sequatchie River population to have a low resilience to stochastic events (Table 5). The species’ recent discovery by TVA is noteworthy; however, the species appears to occur in low densities, the population is isolated from other occupied tributaries, and habitats within the system continue to be affected by a variety of pollutants and land use practices. The species’ habitat and population elements (physical habitat, water quality, reproduction, occurrence extent, and occupied stream length) generally indicate low levels of resiliency.

Draft Sickle Darter SSA 48

Figure 14. Current distribution of the Sickle Darter in the Sequatchie River system, Tennessee, based on fish surveys completed since 2005 (Alford (2019) and TVA unpublished data).

Draft Sickle Darter SSA 49 Table 5. Current resilience estimates for Sickle Darter populations.

Physical Water Occurrence Occupied Current Population Habitat Connectivity Quality Reproduction Extent Stream Length Condition Emory River High 0 Moderate High High High Moderate Upper Clinch River Moderate 0 Moderate Low Low Low Low Powell River Moderate 0 Moderate 0 0 0 Extirpated Little River High 0 Moderate High High High Moderate French Broad River Moderate 0 Moderate 0 0 0 Extirpated North Fork Holston River Low-Moderate 0 Low Low Low High Low Middle Fork Holston River Low-Moderate 0 Low Low Low Low Low South Fork Holston River Low 0 Low 0 0 0 Extirpated Watauga River Low 0 Low 0 0 0 Extirpated Sequatchie River Moderate-High 0 Low Low Low Low Low

Draft Sickle Darter SSA 50

Current Species Representation

Representation describes the ability of a species to adapt to changing environmental conditions over time and is characterized by the breadth of genetic and environmental diversity within and among populations. 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 characteristics across the geographical range and other factors that may be appropriate to the species.

Page and Near (2007, p. 611) studied the genetics of two Sickle Darter specimens collected from the Little River and three Sickle Darter specimens collected from the Emory River, Tennessee. Page and Near (2007, pp. 610-611) found unique haplotypes in all five specimens, and haplotypes within a sampling area (i.e., Little River or Emory River) were more similar than between the two sampling areas. Page and Near (2007, pp. 610-611) did not evaluate individuals from the Clinch River (Copper Creek), Holston River (North Fork Holston River and Middle Fork Holston River), and Sequatchie River systems, so it is unclear if these patterns would hold across the species’ range. Additional collections are needed from across the species’ range to gain a complete and thorough understanding of the species’ population genetics.

Due to a limited amount of species-specific genetic information for the Sickle Darter, we are basing our evaluation of the species’ representation on the extent and variability of environmental diversity (habitat diversity) across the species’ geographical range. Page and Near (2007, pp. 610-611) reported unique haplotypes in five specimens collected from the Emory and Little River systems, but only a limited number of specimens were evaluated and genetics information is lacking for populations in the Clinch River, North Fork Holston River, Middle Fork Holston River, and Sequatchie River.

Historically, the Sickle Darter was known from three Level III ecoregions – Blue Ridge, Ridge and Valley, and Southwestern Appalachians (Woods et al. 2003, entire; Griffith et al. 1998, 2002, entire). The species has been extirpated from the Blue Ridge ecoregion (French Broad River, North Carolina), where it has not been observed since 1940. It continues to occupy the remaining two ecoregions, but it has been extirpated from three tributary systems in the Ridge and Valley ecoregion (Powell River, South Fork Holston River, and Watauga River) and its distribution is limited to short reaches of two streams within the Southwestern Appalachians (Emory River system, Sequatchie River). Based on these factors, there has likely been a reduction in the species’ genetic and environmental diversity over time.

The species’ representation has also been diminished due to construction of multiple dams across the upper Tennessee River drainage. The species’ six extant populations are now isolated, preventing the exchange of novel or beneficial adaptations and reducing the species’ ability to migrate to more suitable habitats when necessary. The species’ representation has been strengthened by its discovery in the Sequatchie River system and the lack of barriers in upstream reaches of some systems (e.g., North Fork Holston River). This has allowed individual Sickle

Draft Sickle Darter SSA 51 Darters to move freely within selected reaches of these systems, thereby maintaining some level of genetic exchange and diversity within each system.

Based on the species’ extirpation from the Blue Ridge ecoregion (e.g. upper French Broad River system); its reduced range within the Ridge and Valley and Southwestern Appalachians ecoregions, including extirpations from several tributary systems; and the loss of connectivity due to dam construction across the upper Tennessee River drainage, we consider the Sickle Darter to exhibit low representation.

Current Species Redundancy

Redundancy describes the ability of a species to withstand catastrophic events. High redundancy “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). For a species to exhibit greater redundancy, the populations should not be completely isolated and immigration and emigration between populations should be achievable.

Redundancy for the Sickle Darter is characterized by having multiple resilient and representative populations distributed across the species’ range. Currently, the species is represented by two populations with moderate resiliency and four populations with low resiliency. Four Sickle Darter populations have been extirpated, including the species’ only population within the Blue Ridge ecoregion. The likelihood that a catastrophic event (e.g., extreme drought) would cause the loss of the Emory River or Little River populations is lower because these populations have higher resiliency than other systems (e.g., higher densities, documented recruitment, and higher occurrence extent), increasing their likelihood of survival during a catastrophic event. The likelihood that a catastrophic event would cause the loss of the remaining populations is higher because the species occurs in lower densities and has more limited distributions within these systems.

Connectivity between extant populations has been eliminated by the construction of dams (e.g., Norris Reservoir) across the upper Tennessee River drainage. If a localized extirpation occurs due to a catastrophic event (e.g., chemical spill), natural recolonization is unlikely because the species’ current populations are isolated and incapable of intertributary movement. Upstream reaches of some systems (e.g., North Fork Holston River) lack movement barriers, allowing the species to move freely within those reaches. This decreases the effect of localized stochastic events that could be detrimental to these populations and lead to extirpation.

Based on our evaluation of population resiliency and the amount of isolation observed across the species’ range, we consider the species to have low redundancy.

Summary of Current Condition

Currently, the Sickle Darter is known from six tributary systems in the Tennessee River drainage – Emory River, Little River, Clinch River, North Fork Holston River, Middle Fork Holston River, and Sequatchie River. Historical populations in the Powell River, French Broad River,

Draft Sickle Darter SSA 52 South Fork Holston River, and Watauga River systems are now considered to be extirpated. Impoundments and water pollution were major factors in the Sickle Darter’s decline during the early to mid-20th Century. Current factors include habitat and water quality degradation, low connectivity, and small population size (e.g., Clinch River). We consider the Emory River and Little River populations to exhibit moderate resiliency, as evidenced by the species’ persistence within these systems for over 45 years, recent and repeated evidence of reproduction and recruitment, a relatively long occupied reach in each system (> 22.5 km (> 14 mi)), and the quality of physical habitat and water quality in both systems. We consider the remaining four populations to exhibit low resiliency. They are represented by fewer documented occurrences, no evidence of recruitment, shorter occupied reaches, and they occur in habitats with limited habitat and water quality. The species’ representation is low because of its reduced range (i.e., a loss of genetic diversity) and a loss of connectivity caused by dam construction. The Sickle Darter occupies only two of three historical ecoregions (Ridge and Valley and Southwestern Appalachians), likely reducing its ability to adapt to changing environmental conditions over time. The species’ redundancy is low based on the number of resilient populations and the amount of isolation observed across the species’ range. This increases the species’ vulnerability to stochastic disturbance and catastrophic events.

Draft Sickle Darter SSA 53 CHAPTER 5. FUTURE SCENARIOS AND SPECIES VIABILITY

In this chapter, we describe how current viability of the Sickle Darter may change over time periods of 10, 30 and 50 years. Similar to our current condition discussion, we evaluate 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 for any of the 3 Rs under each scenario. Our future scenarios differ by considering variations that are predicted in four main elements of change: land cover, urbanization (development), climate, and conservation activity. These scenarios capture the range of plausible viability outcomes that the Sickle Darter will exhibit by 2070. For each scenario, we provide a summary of resilience for each population at 10, 30, and 50 years in the future. Individual components used to characterize future conditions in each scenario are summarized in Appendix B.

To assess changes in land cover, we determined the rate of land cover change between 2006 and 2016 using National Land Cover Database (NLCD) data (Yang et al. 2018, entire). We determined the rate of land cover change for each HUC 8 watershed encompassing Sickle Darter populations. We also reviewed land cover changes at the HUC 10 level in order examine smaller watersheds such as Little River. Total percent forest cover included two NLCD classifications: deciduous forest and evergreen forest. Agricultural land use was calculated using two NLCD classifications: pasture/hay and cultivated crops. Total amount of development included four NLCD development classifications: open space, low intensity, medium intensity, and high intensity. Total amount of wetland was calculated through combining two NLCD classifications: woody wetlands and emergent herbaceous wetlands. Tables summarizing our land use analysis are provided in Appendix C. From 2006 ̶ 2016, dominant land use categories in each tributary system included forest (52.3-71.6 percent of total acreage), developed land (6.0-14.4 percent), and pasture/hay (12.1-36.2 percent). Total percent forest cover increased by 0.4 to 3.7 percent across all tributary systems, while total percent development increased by 0.9 to 3.5 percent. Pasture/hay land use decreased by 1.2 to 3.4 percent across all tributary systems. For our future scenarios, we assumed the same rate of land cover change for Scenario 1 (continuation of current trend) and modified rates of land cover change for Scenarios 2 and 3.

To forecast future development or 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 has been 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. With increased urbanization, forest cover is expected to decrease and water quality and habitat quality are expected to be degraded through increased inputs of point source and non-point source pollutants (e.g., siltation, organic enrichment).

Draft Sickle Darter SSA 54 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 2017). Within the range of the Sickle Darter, the Little River population appears to be most impacted by urbanization. Through 2070, development and urban sprawl is expected to expand and influence areas in Blount County, Tennessee, that previously were unaffected by urbanization. Further, we assess how this increase in developed areas affects populations and the species as a whole.

The Fifth Assessment Report (AR5) by IPCC found that “continued emission of greenhouse gases will cause further warming and long-lasting changes in all components of the climate system, increasing the likelihood of severe, pervasive and irreversible impacts for people and ecosystems” (IPCC 2014, entire). Therefore, we expect climate change to be a driver of change that should be addressed when evaluating the future viability of the Sickle Darter. As described in Chapter 4, the IPCC utilized a suite of alternative emission scenarios (RCPs) in the AR5 to make near-term and long-term climate projections. These scenarios are plausible pathways toward reaching a target radiative forcing. In this assessment, we used a climate change model developed by Alder and Hostetler (2016) to help understand how climate may change in the future and what effects may be observed that impact the Sickle Darter in the upper Tennessee River drainage. We attempt to capture the range of plausible climate outcomes by considering that the frequency and probability of extreme climate scenarios will be greatest under RCP8.5 and intermediate under RCP4.5.

Conservation of the Sickle Darter has been aided by its occupancy of stream systems with multiple listed species (Appendix A) and its inclusion as a species of conservation interest in wildlife conservation strategies in Tennessee and Virginia (TWRA 2015, entire; VDGIF 2015, entire). Over the next 30-50 years, we expect no significant change in public ownership, and we expect state resource agencies to continue to consider the Sickle Darter as a species of management concern.

Scenarios

Scenario 1

In this scenario, public ownership across the Sickle Darter’s range remains at current levels, and actions under state wildlife conservation strategies continue to be implemented. As predicted by the SLEUTH model, small increases in urbanization are expected for all extant populations by 2050 (Figures 15-20) and 2070, with the greatest increase occurring in the Little River system, south of Knoxville, Tennessee (Figure 17). For each 10-year period, we expect changes in forest cover (increase of 1.6 percent), pasture/hay land cover (decrease of 2.2 percent), and developed land (increase of 2.5 percent) to match those observed from 2006-2016 (Appendix C, Tables 19- 20). The current trend in climate continues (moderate RCP of 4.5), and within the next 10 years, a few populations are impacted by either drought or floods, with slightly warmer temperatures. Over the long term (30 – 50 years), drought affects all populations but at intervals and severity levels similar to what has occurred over the last 10 years. A variety of pollutants associated with agriculture and urbanization continue to degrade physical habitat and water quality across the species’ range, and these effects are expected to continue at current levels.

Draft Sickle Darter SSA 55

Figure 15. Probability of urbanization in the Emory River system (HUC 8 shown in blue): 2020 (top) and 2050 (bottom).

Draft Sickle Darter SSA 56

Figure 16. Probability of urbanization in the Clinch and Powell River systems (HUC 10s shown in blue): 2020 (top) and 2050 (bottom).

Draft Sickle Darter SSA 57

Figure 17. Probability of urbanization in the Little River system (HUC 10 shown in blue): 2020 (top) and 2050 (bottom).

Draft Sickle Darter SSA 58

Figure 18. Probability of urbanization in the French Broad River system (HUC 8s shown in blue), 2020 (top) and 2050 (bottom).

Draft Sickle Darter SSA 59

Figure 19. Predicted urbanization levels in the Holston River system (HUC 8s shown in blue), 2020 (top) and 2050 (bottom).

Draft Sickle Darter SSA 60

Figure 20. Predicted urbanization levels in the Sequatchie River system (HUC 8 shown in blue), 2020 (top) and 2050 (bottom).

Draft Sickle Darter SSA 61 Considering all of these factors, we expect both “moderate” populations (i.e., Emory River and Little River) to persist over the next 30 years with no changes in resiliency (Table 6). Over the next 50 years, we expect no change in resiliency for the Emory River population, but we expect resiliency of the Little River population to decrease as a result of increased urbanization in the watershed (Figure 17). We predict no change in resiliency for the Sequatchie River population; however, the low density and short occupied reach of this population increases its vulnerability to stochastic disturbance, such as random fluctuations in birth rates (demographic stochasticity), variations in rainfall (environmental stochasticity), or the effects of anthropogenic activities. We predict reduced resiliency for the Clinch River, North Fork Holston River, and Middle Fork Holston River populations over the next 10-30 years. We expect the Clinch River population to be extirpated within 10 years and the North Fork Holston River and Middle Fork Holston River populations to be extirpated within 30 years due to continued habitat degradation and the effects of small population size.

Table 6. Resiliency of the Sickle Darter under Scenario 1 (red text indicates a negative change in resiliency).

Current Predicted Condition - Scenario 1 Population Condition 10 Years 30 Years 50 Years Emory River Moderate Moderate Moderate Moderate Clinch River Low Extirpated Extirpated Extirpated Powell River Extirpated Extirpated Extirpated Extirpated Little River Moderate Moderate Moderate Low French Broad River Extirpated Extirpated Extirpated Extirpated North Fork Holston River Low Low Extirpated Extirpated Middle Fork Holston River Low Low Extirpated Extirpated South Fork Holston River Extirpated Extirpated Extirpated Extirpated Watauga River Extirpated Extirpated Extirpated Extirpated Sequatchie River Low Low Low Low

Representation

Under Scenario 1, representation of the Sickle Darter is expected to remain at a low level. The species has been extirpated from the Blue Ridge ecoregion (i.e., upper French Broad River system, North Carolina and Tennessee), where it has not been observed since 1940. It continues to occupy historical habitats in its two remaining ecoregions (Ridge and Valley and Southwestern Appalachians), but it has been extirpated from three tributary systems in the Ridge and Valley ecoregion (Powell River, South Fork Holston River, and Watauga River) and its distribution is limited to short reaches of two streams within the Southwestern Appalachians (Emory River system, Sequatchie River). The species’ representation has also been diminished due to construction of multiple dams across the upper Tennessee River drainage. The species’ six extant populations are now isolated, preventing the exchange of novel or beneficial adaptations and reducing the species’ ability to migrate to more suitable habitats when necessary.

The species’ representation has been strengthened by its recent discovery in the Sequatchie River system and the lack of barriers in upstream reaches of some systems (e.g., North Fork Holston

Draft Sickle Darter SSA 62 River). This has allowed individual Sickle Darters to move freely within selected reaches of these systems, thereby maintaining some level of genetic exchange and diversity within each system.

Redundancy

Under Scenario 1, redundancy of the Sickle Darter is expected to remain at a low level. The species is represented by two populations with moderate resiliency and four populations with low resiliency. The species’ low densities and restricted distribution in the Clinch River, North Fork Holston River, Middle Fork Holston River, and Sequatchie River system increase the likelihood that these populations could be extirpated during a catastrophic event (e.g., extreme drought or chemical spill). The species’ resiliency is higher in the Emory River and Little River systems, but the linear distribution of these populations increases their vulnerability to chemical spills or similar catastrophic events.

Connectivity between extant populations has been reduced, or likely eliminated, by the construction of dams (e.g., Norris Reservoir). These populations are now isolated, preventing the exchange of novel or beneficial adaptations and reducing the species’ ability to migrate to more suitable habitats when necessary. If a localized extirpation occurs due to a catastrophic event (e.g., chemical spill), natural recolonization is unlikely because the species’ current populations are isolated and incapable of intertributary movement. Upstream reaches of some systems (e.g., North Fork Holston River) lack movement barriers, allowing the species to move freely within these reaches. This decreases the effect of localized stochastic events that could be detrimental to these populations and lead to extirpation.

Scenario 2

In this scenario, we predict a number of improved conditions and positive outcomes that lead to overall greater resiliency, representation, and redundancy of the Sickle Darter. This scenario assumes no changes in public ownership, but we predict that urbanization rates will be reduced from those predicted by the SLUETH model. For each 10-year period, we expect forest cover to increase by about 2.3 percent (50 percent rate increase compared to Scenario 1), while we expect pasture/hay land cover to decrease at the same level (decrease of 2.2 percent) and developed land to increase by about 3.8 percent (50 percent rate increase) (Figures 19, 21). The current trend in climate improves, with lower annual increases in temperature and less severe droughts or floods in the short term (RCP < 4.5). Over the long term (30 – 50 years), drought affects all populations but at intervals and severity levels lower than what has occurred over the last 10 years. Conservation efforts will increase through state wildlife action plans, and other partnerships with federal, state, and non-governmental partners. These actions will contribute to improved water quality conditions, increases in forest and riparian cover, and reductions in point source and non-point source pollutants in all historical tributary systems. Within the next 10-30 years, we expect improved resiliency in the Clinch River (e.g., Copper Creek) and North Fork Holston River populations, and we predict the rediscovery or reintroduction of the species in the Powell River system and portions of the French Broad River system (e.g., Little Pigeon River), where the species has not been observed since the 1890s and 1970s, respectively (Table 7). We

Draft Sickle Darter SSA 63 also predict the removal of Peery’s Mill Dam and subsequent upstream expansion of the Sickle Darter population in the Little River.

Table 7. Resiliency of the Sickle Darter under Scenario 2 (green text indicates a positive change in resiliency).

Current Predicted Condition - Scenario 2 Population Condition 10 Years 30 Years 50 Years Emory River Moderate Moderate Moderate Moderate Clinch River Low Low Low Low Powell River Extirpated Extirpated Low Low Little River Moderate Moderate Moderate Moderate French Broad River Extirpated Extirpated Low Low North Fork Holston River Low Low Low Low Middle Fork Holston River Low Low Low Low South Fork Holston River Extirpated Extirpated Extirpated Extirpated Watauga River Extirpated Extirpated Extirpated Extirpated Sequatchie River Low Low Low Low

Representation

Under Scenario 2, representation of the Sickle Darter is expected to remain at a low level. Reintroduction of the species in the Powell River and French Broad River systems will bolster the species’ resiliency and redundancy, but the species’ genetic and ecological diversity will remain the same.

Redundancy

Under Scenario 2, redundancy of the Sickle Darter will increase due to the species’ reintroduction in the Powell River and French Broad River systems, and its improved resiliency within the Clinch River and North Fork Holston River systems. These outcomes will decrease the likelihood that a catastrophic event, such as an extreme drought or pollution event, would lead to the species’ extinction.

Connectivity between extant Sickle Darter populations has been reduced, or likely eliminated, by the construction of dams (e.g., Norris Reservoir). No future dams are anticipated under this scenario, allowing the species to move freely within these systems, with no dispersal barriers preventing movement between the mainstem and multiple tributaries. Increased connectivity within these systems decreases the effect of localized stochastic events that could be detrimental to these populations and lead to extirpation. Under Scenario 2, we expect the Sickle Darter to exhibit low-moderate redundancy.

Draft Sickle Darter SSA 64 Scenario 3

In this scenario, we predict that NLCD rates of land use change for agriculture and development will be higher than those observed from 2006-2016, and urbanization rates will be higher than those predicted by the SLEUTH model. For each 10-year period, we expect forest cover to decrease by about 1.5 percent (200 percent rate decrease compared to Scenario 1) and pasture/hay land cover to decrease by about 4.3 percent (100 percent rate decrease). For each 10-year period, we also expect developed land to increase by about 5.2 percent (100 percent rate increase) (Figures 19, 22). The current trend in climate worsens (high RCP of 8.5), and within the next 10 years, populations are impacted by either drought or flood, with warmer stream temperatures. Over the long term (30–50 years), drought affects all populations at slightly higher intervals and severity levels than those observed over the last 10 years. Some conservation actions will continue across the species’ range, but there will be a net decrease in these activities due to reduced agency funding. All of these actions and conditions will result in declining habitat and water quality conditions that will negatively affect the resilience of extant populations. We predict reduced resiliency for the Clinch River, North Fork Holston River, Middle Fork Holston River, and Sequatchie River populations, resulting in the extirpation of these populations within 30 years. Sickle Darter abundance in these systems is low, and stream habitats will continue to be affected by a variety of pollutants associated with agriculture, legacy coal mining, and urbanization. We also predict reduced resiliency for the Emory River and Little River populations within 30 years (Table 8).

Representation

Under Scenario 3, representation of the Sickle Darter is expected to remain at a low level. The species’ genetic and ecological diversity will decrease due to extirpation of the Clinch River, North Fork Holston River, Middle Fork Holston River, and Sequatchie River populations. These extirpations will reduce the species’ genetic and ecological diversity, thereby reducing the species’ ability to adapt to changing environmental conditions.

Table 8. Resiliency of the Sickle Darter under Scenario 3 (red text indicates a negative change in resiliency). Current Predicted Condition - Scenario 3 Population Condition 10 Years 30 Years 50 Years Emory River Moderate Moderate Low Low Clinch River Low Extirpated Extirpated Extirpated Powell River Extirpated Extirpated Extirpated Extirpated Little River Moderate Moderate Low Low French Broad River Extirpated Extirpated Extirpated Extirpated North Fork Holston River Low Low Extirpated Extirpated Middle Fork Holston River Low Low Extirpated Extirpated South Fork Holston River Extirpated Extirpated Extirpated Extirpated Watauga River Extirpated Extirpated Extirpated Extirpated Sequatchie River Low Low Extirpated Extirpated

Draft Sickle Darter SSA 65

Redundancy Under Scenario 3, redundancy of the Relict Darter is expected to remain at a low level. The species’ extirpation from the Clinch River, North Fork Holston River, Middle Fork Holston River, and Sequatchie River systems will reduce its range significantly, making it more vulnerable to catastrophic events such as an extreme droughts or chemical spills. The species’ redundancy will also be weakened by lower resiliency of the Emory River and Little River populations, which will be faced with declining physical habitat and water quality conditions.

Summary of Species’ Future Viability

The future scenario assessment was developed to understand how viability of the Sickle Darter may change over the course of 10, 30, and 50 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 upper Tennessee River drainage and those changes that have the potential to impact the Sickle Darter. These scenarios considered four elements of change: land cover, urbanization, climate, and conservation activity.

Under Scenario 1 (continuation of current trend), conservation efforts by the Service and its partners are expected to continue, and no significant changes are expected with respect to land cover, urbanization, climate, or habitat conditions. Three of the Sickle Darter’s six extant populations are expected to persist, with resiliency estimates remaining at current levels. Three extant populations, Clinch River, Middle Fork Holston River, and North Fork Holston River, are expected to be extirpated within 30 years. The species’ redundancy and representation are expected to remain at low levels.

Under Scenario 2, (improving trend), we predict habitat conditions throughout the upper Tennessee River drainage to improve due to increased conservation efforts and improving land use practices (e.g. greater forest cover and reduced agricultural and development effects). Based on these factors, resiliency of all extant populations is expected to remain at current levels or increase, and the species is expected to be rediscovered or reintroduced into portions of the Powell River system and French Broad River system. The species’ redundancy will increase to a low-moderate level; representation is expected to remain at a low level.

Under Scenario 3 (worsening trend), habitat conditions are expected to decline within the upper Tennessee River drainage due to reductions in forest cover, increased urbanization and agricultural activities, and worsening climate trends. Combined with reduced conservation efforts, these factors will have a negative effect on population resiliency, resulting in extirpation of the Clinch River, North Fork Holston River, Middle Fork Holston River, and Sequatchie River populations. Loss of these populations will contribute to reduced redundancy and representation, with overall species’ redundancy and representation remaining at low levels.

Draft Sickle Darter SSA 66 Uncertainty

Through the course of this analysis, it was necessary to make certain assumptions to assess current and future conditions. These assumptions introduce some uncertainty to our estimates of species viability, and our future scenarios are projections based only on current trends and predictive models. The following are uncertainties recognized in this assessment report:

• We assumed that the species’ historical range is represented by known collection records. The actual historical range prior to European colonization is unknown and may have included other Tennessee River tributaries or portions of the Tennessee River mainstem. • To determine the species’ current range, we used all records obtained between 2005 and 2019 and evaluated how those records compared to historical collections. We chose this time period based on our review of available survey records, the species’ life history, and discussions with species’ experts. • We divided the Sickle Darter’s range into 10 analytical units or populations: Emory River, Clinch River, Powell River, Little River, French Broad River, North Fork Holston River, Middle Fork Holston River, South Fork Holston River, Watauga River, and Sequatchie River. We treated these stream systems as separate populations (analytical units) based on known occurrence records and the species’ fragmented distribution within the upper Tennessee River drainage. • Each component (habitat and population) used to assess the species’ condition (resiliency) was weighted equally. Components and corresponding condition categories were finalized through discussions with the Sickle Darter expert team. • Our population estimates for the Emory River and Little River populations were based on an approach used by Eisenhour et al. (2011, p. 15) to estimate population size for the Longhead Darter in Kinniconick Creek, Kentucky. We used snorkeling survey data (total abundance of Sickle Darters in each reach) collected by Alford (2019, pp. 24-33) at several survey reaches in each system. We assumed that 20-50 percent of Sickle Darters were observed in each survey reach, and we extrapolated from the total survey reach length to the occupied reach length in each system to arrive at our population estimates. Population estimates were not calculated for other systems due to the low abundance in those systems (< 10 individuals observed since 2005). • We assumed that levels of public ownership within extant populations will not change over time. • Future conservation efforts are dependent on funding availability, available conservation opportunities, and the willing cooperation of our partners, so only a portion of actions may be undertaken in the future. • We used an available urbanization (development) model (SLEUTH) to predict how future urbanization could impact habitats used by the Sickle Darter. This model uses spatial observations of past urban growth and transportation networks to make predictions about future urbanization rates. We acknowledge that this model does not account for other potential sources of habitat disturbance or water quality impairment (e.g., agriculture, surface coal mining) that could impact the species in the future. Currently, we are unaware of models that could evaluate future threats associated with these activities.

Draft Sickle Darter SSA 67 Summary

Currently, the Sickle Darter is known from six tributary systems in the Tennessee River drainage – Emory River, Little River, Clinch River, North Fork Holston River, Middle Fork Holston River, and Sequatchie River. Historical populations in the Powell river, French Broad River, South Fork Holston River, and Watauga River systems are now considered to be extirpated. Impoundments and water pollution were major factors in the Sickle Darter’s decline during the early to mid-20th Century. Current factors include continued habitat and water quality degradation, low connectivity, and small population size (e.g., Clinch River). The Emory River and Little River populations exhibit moderate resiliency, as evidenced by the species’ persistence within these systems for over 45 years, recent and repeated evidence of reproduction and recruitment, a relatively long occupied reach in each system (> 24 km (> 15 mi)), and the quality of physical habitat and water quality in both systems. The remaining four populations exhibit low resiliency based on fewer documented occurrences, no evidence of recruitment, shorter occupied reaches, and reduced habitat and water quality conditions. The species’ representation is low because of its reduced range (i.e., a loss of genetic diversity) and a loss of connectivity caused by dam construction. The Sickle Darter occupies only two of three historical ecoregions (Ridge and Valley and Southwestern Appalachians), likely reducing its ability to adapt to changing environmental conditions over time. The species’ redundancy is low based our evaluation of population resiliency and the amount of isolation observed across the species’ range. This increases the species’ vulnerability to catastrophic events.

Our future scenarios assessment used four elements of change (urbanization, land cover change, climate change, and conservation activity) to assess the viability of the species over three time periods – 10, 30, and 50 years. These scenarios captured the range of likely viability outcomes that the Sickle Darter will exhibit by 2070. Under Scenario 1 (continuation of current trend), three of the Sickle Darter’s six extant populations are expected to persist, with resiliency estimates remaining at current levels. Three extant populations, Clinch River, Middle Fork Holston River, and North Fork Holston River, are expected to be extirpated within 30 years. The species’ redundancy and representation are expected to remain at low levels. Under Scenario 2, (improving trend), we predict habitat conditions throughout the upper Tennessee River drainage to improve due to increased conservation efforts and improving land use practices (e.g. greater forest cover and reduced agricultural and development effects). Resiliency of all extant populations is expected to remain at current levels or increase, and the species is expected to be rediscovered or reintroduced into portions of the Powell River system and French Broad River system. The species’ redundancy will increase to a low-moderate level; representation is expected to remain at a low level. Under Scenario 3 (worsening trend), habitat conditions are expected to decline within the upper Tennessee River drainage due to reductions in forest cover, increased urbanization and agricultural activities, and worsening climate trends. All of these factors will have a negative effect on population resiliency, resulting in extirpation of the Clinch River, North Fork Holston River, Middle Fork Holston River, and Sequatchie River populations. Loss of these populations will contribute to reduced redundancy and representation, with overall species’ redundancy and representation remaining at low levels.

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Draft Sickle Darter SSA 78

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Draft Sickle Darter SSA 79 Appendix A

Table 9. Summary of federally endangered and threatened species occupying habitats within the Sickle Darter’s historical range in North Carolina, Tennessee, and Virginia (FE = federally endangered; FT = federally threatened).

Emory Clinch Powell Little French North Fork Middle Fork South Fork Watauga Sequatchie Species River River River River Broad Holston Holston Holston River River Fishes: Erimystax cahni Slender Chub, FT X X Etheostoma percnurum Duskytail Darter, FE X X Noturus flavipinnis Yellowfin Madtom, FT X X Noturus stanauli Pygmy Madtom, FE X Percina tanasi Snail Darter, FT X Cyprinella monacha Spotfin Chub, FE X X X X

Mussels: Cumberlandia monodonta Spectaclecase, FE X X Cyprogenia stegaria Fanshell Mussel, FE X Dromus dromas Dromedary Mussel, FE X X Epioblasma brevidens X X Cumberlandian Combshell, FE Epioblasma capsaeformis X X Oyster Mussel, FE X X Epioblasma florentina aureola Golden Riffleshell, FE X X

Draft Sickle Darter SSA 80 Emory Clinch Powell Little French North Fork Middle Fork South Fork Watauga Sequatchie

Species River River River River Broad Holston Holston Holston River River Epioblasma triquetra Snuffbox Mussel, FE X X Fusconaia cor Shiny Pigtoe, FE X X X Fusconaia cuneolus Finerayed Pigtoe, FE X X X Hemistena lata Cracking Pearlymussel, FE X X Lampsilis abrupta Pink Mucket, FE X X Lemiox rimosus Birdwing Pearlymussel, FE X X X Lexingtonia dolabelloides Slabside Pearlymussel, FE X X X X Pegias fabula Littlewing Pearlymussel, FE X X Plethobasus cyphyus Sheepnose, FE X X Pleurobema plenum Rough Pigtoe, FE X Ptychobranchus subtentum Fluted Kidneyshell, FE X X X X Quadrula cylindrica X X Rough Rabbitsfoot, FE Quadrula intermedia X Cumberland Monkeyface, FE Villosa fabalis

Rayed Bean, FE Villosa perpurpurea Purple Bean, FE X X

Draft Sickle Darter SSA 81 Appendix B

Tables 10-12. Future resilience estimates (10-year, 30-Year, and 50-Year) for the Sickle Darter – Scenario 1.

Physical Water Occurrence Occupied Current 10-Year Population Habitat Quality Connectivity Reproduction Extent Stream Length Condition Future Condition Emory River High Moderate 0 Moderate High High Moderate Moderate Clinch River Low Moderate 0 0 0 0 Low Extirpated Powell River Moderate Moderate 0 0 0 0 Extirpated Extirpated Little River High Moderate 0 Moderate High High Moderate Moderate French Broad River Moderate Moderate 0 0 0 0 Extirpated Extirpated North Fork Holston River Low-Moderate Low 0 Low Low High Low Low Middle Fork Holston River Low-Moderate Low 0 Low Low Low Low Low South Fork Holston River Low Low 0 0 0 0 Extirpated Extirpated Watauga River Low Low 0 0 0 0 Extirpated Extirpated Sequatchie River Moderate-High Low 0 Low Low Low Low Low

Physical Water Occurrence Occupied Current 30-Year Population Habitat Quality Connectivity Reproduction Extent Stream Length Condition Future Condition Emory River Moderate Moderate 0 Moderate High High Moderate Moderate Clinch River Low Low 0 0 0 0 Low Extirpated Powell River Low Low 0 0 0 0 Extirpated Extirpated Little River Moderate Moderate 0 Moderate High High Moderate Moderate French Broad River Low Low 0 0 0 0 Extirpated Extirpated North Fork Holston River Low Low 0 0 0 0 Low Extirpated Middle Fork Holston River Low Low 0 0 0 0 Low Extirpated South Fork Holston River Low Low 0 0 0 0 Extirpated Extirpated Watauga River Low Low 0 0 0 0 Extirpated Extirpated Sequatchie River Moderate-High Low 0 Low Low Low Low Low

Physical Water Occurrence Occupied Current 50-Year Population Habitat Quality Connectivity Reproduction Extent Stream Length Condition Future Condition Emory River Moderate Moderate 0 Moderate High High Moderate Moderate Clinch River Low Low 0 0 0 0 Low Extirpated Powell River Low Low 0 0 0 0 Extirpated Extirpated Little River Low Low 0 Low Low Moderate Moderate Low French Broad River Low Low 0 0 0 0 Extirpated Extirpated North Fork Holston River Low Low 0 0 0 0 Low Extirpated Middle Fork Holston River Low Low 0 0 0 0 Low Extirpated South Fork Holston River Low Low 0 0 0 0 Extirpated Extirpated Watauga River Low Low 0 0 0 0 Extirpated Extirpated Sequatchie River Moderate-High Low 0 Low Low Low Low Low

Draft Sickle Darter SSA 82

Tables 13-15. Future resilience estimates (10-year, 30-Year, and 50-Year) for the Sickle Darter – Scenario 2.

Physical Water Occurrence Occupied Current 10-Year Population Habitat Quality Connectivity Reproduction Extent Stream Length Condition Future Condition Emory River High Moderate 0 Moderate High High Moderate Moderate Clinch River Moderate Moderate 0 Low Low Low Low Low Powell River Moderate Moderate 0 0 0 0 Extirpated Extirpated Little River High Moderate 0 Moderate High High Moderate Moderate French Broad River Moderate Moderate 0 0 0 0 Extirpated Extirpated North Fork Holston River Low-Moderate Low 0 Low Low High Low Low Middle Fork Holston River Low-Moderate Low 0 Low Low Low Low Low South Fork Holston River Low Low 0 0 0 0 Extirpated Extirpated Watauga River Low Low 0 0 0 0 Extirpated Extirpated Sequatchie River Moderate-High Low 0 Low Low Low Low Low

Physical Water Occurrence Occupied Current 30-Year Population Habitat Quality Connectivity Reproduction Extent Stream Length Condition Future Condition Emory River High Moderate 0 Moderate High High Moderate Moderate Clinch River Moderate Moderate 0 Low Low Low Low Low Powell River Moderate Moderate 0 Low Low Low Extirpated Low Little River High Moderate 0 Moderate High High Moderate Moderate French Broad River Moderate Moderate 0 Low Low Low Extirpated Low North Fork Holston River Moderate Low 0 Low Low High Low Low Middle Fork Holston River Moderate Low 0 Low Low Low Low Low South Fork Holston River Low Low 0 0 0 0 Extirpated Extirpated Watauga River Low Low 0 0 0 0 Extirpated Extirpated Sequatchie River Moderate-High Low 0 Low Low Low Low Low

Physical Water Occurrence Occupied Current 50-Year Population Habitat Quality Connectivity Reproduction Extent Stream Length Condition Future Condition Emory River High Moderate 0 Moderate High High Moderate Moderate Clinch River Moderate Moderate 0 Low Low Low Low Low Powell River Moderate Moderate 0 Low Low Low Extirpated Low Little River High Moderate 0 Moderate High High Moderate Moderate French Broad River Moderate Moderate 0 Low Low Low Extirpated Low North Fork Holston River Moderate Moderate 0 Low Low High Low Low Middle Fork Holston River Moderate Moderate 0 Low Low Low Low Low South Fork Holston River Low Low 0 0 0 0 Extirpated Extirpated Watauga River Low Low 0 0 0 0 Extirpated Extirpated Sequatchie River Moderate-High Moderate 0 Low Low Low Low Low

Draft Sickle Darter SSA 83 Tables 16-18. Future resilience estimates (10-year, 30-Year, and 50-Year) for the Sickle Darter – Scenario 3.

Physical Water Occurrence Occupied Current 10-Year Population Habitat Quality Connectivity Reproduction Extent Stream Length Condition Future Condition Emory River High Moderate 0 Moderate High High Moderate Moderate Clinch River Low Low 0 0 0 0 Low Extirpated Powell River Moderate Moderate 0 0 0 0 Extirpated Extirpated Little River High Moderate 0 Moderate High High Moderate Moderate French Broad River Moderate Moderate 0 0 0 0 Extirpated Extirpated North Fork Holston River Low-Moderate Low 0 Low Low Moderate Low Low Middle Fork Holston River Low-Moderate Low 0 Low Low Low Low Low South Fork Holston River Low Low 0 0 0 0 Extirpated Extirpated Watauga River Low Low 0 0 0 0 Extirpated Extirpated Sequatchie River Moderate-High Low 0 Low Low Low Low Low

Physical Water Occurrence Occupied Current 30-Year Population Habitat Quality Connectivity Reproduction Extent Stream Length Condition Future Condition Emory River Low Moderate 0 Moderate Moderate Low Moderate Low Clinch River Low Low 0 0 0 0 Low Extirpated Powell River Low Low 0 0 0 0 Extirpated Extirpated Little River Low Moderate 0 Moderate Moderate Low Moderate Low French Broad River Low Low 0 0 0 0 Extirpated Extirpated North Fork Holston River Low Low 0 0 0 0 Low Extirpated Middle Fork Holston River Low Low 0 0 0 0 Low Extirpated South Fork Holston River Low Low 0 0 0 0 Extirpated Extirpated Watauga River Low Low 0 0 0 0 Extirpated Extirpated Sequatchie River Moderate Low 0 0 0 0 Low Extirpated

Physical Water Occurrence Occupied Current 50-Year Population Habitat Quality Connectivity Reproduction Extent Stream Length Condition Future Condition Emory River Low Moderate 0 Moderate Moderate Low Moderate Low Clinch River Low Low 0 0 0 0 Low Extirpated Powell River Low Low 0 0 0 0 Extirpated Extirpated Little River Low Low 0 Low Low Low Moderate Low French Broad River Low Low 0 0 0 0 Extirpated Extirpated North Fork Holston River Low Low 0 0 0 0 Low Extirpated Middle Fork Holston River Low Low 0 0 0 0 Low Extirpated South Fork Holston River Low Low 0 0 0 0 Extirpated Extirpated Watauga River Low Low 0 0 0 0 Extirpated Extirpated Sequatchie River Low Low 0 0 0 0 Low Extirpated

Draft Sickle Darter SSA 84 Appendix C

Table 19. Land cover summary and percent land cover change for the upper Tennessee River drainage (2006-2016). Percent Land Cover (2006) Tributary System Developed Forest Pasture/Hay Row Crop Shrub/Grass Wetland Barren Land Emory River 8.06 70.37 14.03 0.01 6.02 0.15 0.48 Clinch-Powell River 7.30 64.76 17.00 0.03 8.07 0.08 0.78 Little River 13.96 65.04 18.57 0.79 1.03 0.16 0.03 French Broad River 12.60 70.99 12.41 0.70 1.52 0.13 0.29 Holston River 10.56 63.42 22.43 0.20 2.11 0.10 0.09 Sequatchie River 5.89 64.37 20.89 1.25 6.81 0.48 0.11

Percent Land Cover (2016) Tributary System Developed Forest Pasture/Hay Row Crop Shrub/Grass Wetland Barren Land Emory River 8.33 71.62 13.77 0.05 4.77 0.16 0.44 Clinch-Powell River 7.36 65.79 16.75 0.06 7.24 0.08 0.82 Little River 14.44 65.31 17.93 0.89 0.81 0.16 0.03 French Broad River 12.98 71.20 12.06 0.72 1.24 0.13 0.29 Holston River 10.83 64.17 22.09 0.23 1.44 0.11 0.10 Sequatchie River 6.00 66.73 20.30 1.59 4.57 0.50 0.12

Percent Land Cover Change (2006-2016) Tributary System Developed Forest Pasture/Hay Row Crop Shrub/Grass Wetland Barren Land Emory River 3.36 1.78 -1.84 424.90 -20.71 0.43 -8.88 Clinch-Powell River 0.91 1.59 -1.47 87.61 -10.31 4.43 6.20 Little River 3.47 0.42 -3.45 12.64 -21.40 0.23 -11.39 French Broad River 3.04 0.29 -2.82 3.78 -18.25 5.82 0.36 Holston River 2.52 1.18 -1.53 13.14 -31.80 5.64 6.56 Sequatchie River 1.87 3.66 -2.86 27.04 -32.91 4.95 2.78

Draft Sickle Darter SSA 85 Table 20. Summary of predicted percent forest cover, pasture/hay, and developed land cover at future time periods of 10 and 30 years (Scenario 1). Scenario 1 assumes the same rate of change observed for each land cover type in the upper Tennessee River drainage between 2006 and 2016.

Forest Cover Pasture/Hay Development 2016 % Change Predicted 2030 2050 2016 % Change Predicted 2030 2050 2016 % Change Predicted 2030 2050 Population (%) 2006-2016 Annual (%) (%) (%) 2006-2016 Annual (%) (%) (%) 2006-2016 Annual (%) (%) Change (%) Change (%) Change (%)

Emory River 71.62 1.78 0.178 73.41 75.96 13.77 -1.84 -0.184 13.41 12.91 8.33 3.36 0.336 8.72 9.28

Clinch-Powell River 65.79 1.59 0.159 67.26 69.35 16.75 -1.47 -0.147 16.41 15.91 7.36 0.91 0.091 7.45 7.59

Little River 65.31 0.42 0.042 65.70 66.25 17.93 -3.45 -0.345 17.06 15.83 14.44 3.47 0.347 15.14 16.14

French Broad River 71.20 0.29 0.029 71.49 71.91 12.06 -2.82 -0.282 11.58 10.90 12.98 3.04 0.304 13.53 14.32

Holston River 64.17 1.18 0.118 65.23 66.75 22.09 -1.53 -0.153 21.62 20.94 10.83 2.52 0.252 11.21 11.76

Sequatchie River 66.73 3.66 0.366 70.15 75.03 20.30 -2.86 -0.286 19.49 18.33 6.00 1.87 0.187 6.16 6.38

Table 21. Summary of predicted percent forest cover, pasture/hay, and developed land cover at future time periods of 10 and 30 years (Scenario 2). Scenario 2 assumes a 50 percent rate increase for forest cover, no rate change for pasture/hay, and a 50 percent rate decrease for development compared to land cover changes observed between 2006 and 2016.

Forest Cover Pasture/Hay Development 2016 % Change Predicted 2030 2050 2016 % Change Predicted 2030 2050 2016 % Change Predicted 2030 2050 Population (%) 2006-2016 Annual (%) (%) (%) 2006-2016 Annual (%) (%) (%) 2006-2016 Annual (%) (%) Change (%) Change (%) Change (%)

Emory River 71.62 1.78 0.267 74.30 78.13 13.77 -1.84 0.184 13.41 12.91 8.33 3.36 0.168 8.53 8.81

Clinch-Powell River 65.79 1.59 0.239 67.99 71.13 16.75 -1.47 0.147 16.41 15.91 7.36 0.91 0.045 7.41 7.47

Little River 65.31 0.42 0.063 65.89 66.72 17.93 -3.45 0.345 17.06 15.83 14.44 3.47 0.173 14.79 15.29

French Broad River 71.20 0.29 0.044 71.64 72.26 12.06 -2.82 0.282 11.58 10.90 12.98 3.04 0.152 13.26 13.65

Holston River 64.17 1.18 0.177 65.76 68.04 22.09 -1.53 0.153 21.62 20.94 10.83 2.52 0.126 11.02 11.29

Sequatchie River 66.73 3.66 0.549 71.86 79.19 20.30 -2.86 0.286 19.49 18.33 6.00 1.87 0.094 6.08 6.19

Draft Sickle Darter SSA 86

Table 22. Summary of predicted percent forest cover, pasture/hay, and developed land cover at future time periods of 10 and 30 years (Scenario 3). Scenario 3 assumes a 200 percent rate decrease for percent forest cover, a 100 percent rate decrease for pasture/hay, and a 100 percent rate increase for developed land compared to land use changes observed between 2006 and 2016.

Forest Cover Pasture/Hay Development 2016 % Change Predicted 2030 2050 2016 % Change Predicted 2030 2050 2016 % Change Predicted 2030 2050 Population (%) 2006-2016 Annual (%) (%) (%) 2006-2016 Annual (%) (%) (%) 2006-2016 Annual (%) (%) Change (%) Change (%) Change (%)

Emory River 71.62 1.78 -0.178 69.83 67.28 13.77 -1.84 0.369 13.06 12.04 8.33 3.36 0.369 9.11 10.23

Clinch-Powell River 65.79 1.59 -0.159 64.32 62.23 16.75 -1.47 0.294 16.06 15.07 7.36 0.91 0.181 7.55 7.81

Little River 65.31 0.42 -0.042 64.92 64.37 17.93 -3.45 0.690 16.20 13.72 14.44 3.47 0.694 15.84 17.85

French Broad River 71.20 0.29 -0.029 70.91 70.49 12.06 -2.82 0.564 11.11 9.75 12.98 3.04 0.608 14.08 15.66

Holston River 64.17 1.18 -0.118 63.11 61.59 22.09 -1.53 0.306 21.14 19.79 10.83 2.52 0.503 11.59 12.68

Sequatchie River 66.73 3.66 -0.366 63.31 58.43 20.30 -2.86 0.572 18.68 16.35 6.00 1.87 0.374 6.31 6.76

Draft Sickle Darter SSA 87