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D.E. Schilling, A.T. Phipps, J.W. Jones, and E.M. Hallerman
22001177 SOUTHEASTERN NATURALIST 1V6o(1l.) :1160,5 N–1o1. 61
A Survey of Freshwater Mussels (Unionidae) in Little River,
Blount County, Tennessee
Daniel E. Schilling*,1, Andrew T. Phipps1, Jess W. Jones1,2, and Eric M. Hallerman1
Abstract - Following the collection of a putative undescribed species in the genus Pleurobema
in 2012, we surveyed the freshwater mussel fauna of Little River, Blount County,
TN, to determine species diversity and relative abundances. At 18 main-stem sites, we
sampled 3053 live specimens representing 12 mussel species and 1 fresh-dead individual
representing another. An additional species represented by a relic shell was collected, bringing
the total to 14 mussel species sampled during this survey. Villosa species comprised 77%
of total live mussels sampled. Among the extant mussels were two federally endangered
species: Fusconaia cuneolus (Finerayed Pigtoe) was confirmed to persist in the river, while
Pleuronaia dolabelloides (Slabside Pearlymussel) represents a new drainage record. Several
other mussels collected are considered imperiled globally, including Alasmidonta viridis
(Slippershell Mussel), Lampsilis ovata (Pocketbook), Medionidus conradicus (Cumberland
Moccasinshell), Pleurobema oviforme (Tennessee Clubshell), Pleuronaia barnesiana (Tennessee
Pigtoe), and Villosa vanuxemensis (Mountain Creekshell). A total of 319 individuals
of the putative new species Pleurobema sp. cf. oviforme were sampled at 9 sites, 215 at 1
site. A total of 857 individuals of a putative undescribed species in the genus Villosa were
sampled at 9 sites. These 2 putative species (Pleurobema sp. cf. oviforme and Villosa sp. cf.
iris) are likely endemic to Little River, TN, and may be in need of state and federal protection.
Mussel densities declined downstream from the mouth of Ellejoy Creek, indicating
that water-quality issues may be occurring in this reach of the river.
Introduction
North America has the highest diversity of freshwater mussels in the world,
with 302 recognized species (Haag 2012). However, the number of recognized
mussel species is increasing with the description of new taxa based primarily on
the application of more intensive morphological and molecular genetic assessments
(Haag and Williams 2014). Such assessments, especially molecular genetics, have
revealed previously unrecognized cryptic species (Bickford et al. 2007). Because
freshwater taxa extinction rates are 5 times greater than those of terrestrial taxa
(Ricciardi and Rasmussen 1999), it is likely that many unrecognized freshwater
taxa have already gone extinct.
The Tennessee River system contains the most diverse mussel fauna in North
America, with a total of 102 mussels recorded as native and 15 as endemic (Parmalee
and Bogan 1998). The upper Tennessee River system above Walden’s Gorge
1Department of Fish and Wildlife Conservation, Virginia Polytechnic Institute and State
University, Blacksburg, VA 24061-0321. 2US Fish and Wildlife Service, Department of Fish
and Wildlife Conservation, Virginia Polytechnic Institute and State University, Blacksburg,
VA 24061-0321. *Corresponding author: Daniel Schilling - dschilli@vt.edu.
Manuscript Editor: Arthur Bogan
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historically contained 82 species (Parmalee and Bogan 1998). Little River is located
in east Tennessee and flows into the Tennessee River at approximately river
kilometer (rkm) 1022.7 (river mile 635.5). Only 2 previous studies documented the
mussel fauna of the Little River drainage (Table 1). Ortmann (1918) reported on
collections from 4 sites in Little River and 1 site in a tributary, Pistol Creek, documenting
12 species in the mainstem and 5 species from Pistol Creek, for a total of
14 species. However, visual inspection of specimen photographs by D. Schilling in
2016 provided by the Carnegie Museum of Natural History revealed that Ortmann
likely also collected the 2 additional putative species sampled and reported in this
study, which could bring the total known historically from the drainage to 16 species.
The Tennessee Valley Authority (TVA) sampled mussels from 2 mainstem
sites in 1981 and recorded 7 species in their unpublished report (Hickman and
Harned 1981). Because the mussel fauna of the river is not well known, contains
species that are now federally listed, and contains putative undescribed species in
the genera Pleurobema and Villosa (Schilling et al. 2015), a systematic survey of
the river’s mussel fauna was undertaken to document mussel diversity and abundance
in the river.
Table 1. Freshwater mussels of the Little River, Blount County, TN, recorded by Ortmann (1918)A
at 4 sites sampled in the early 1900s and by Hickman and Harned (1981) at 2 sites sampled in 1981,
and by the current study at 18 sites sampled in the river mainstem. * indicates federally endangered
species; + indicates collections made during previous surveys in Little River at sites now inundated
by Fort Loudoun Reservoir.
This
Scientific name Common name Authority 1918 1981 study
Actinonaias pectorosa Pheasantshell (Lamark) X
Alasmidonta viridis Slippershell Mussel (Rafinesque) X FD
Amblema plicata+ Threeridge+ (Say) X
Cumberlandia monodonta*+ Spectaclecase*+ (Say) X
Elliptio dilatata Spike (Rafinesque) X X
Epioblasma triquetra*+ Snuffbox*+ (Rafinesque) X
Fusconaia cuneolus* Finerayed Pigtoe* (Lea) X X
Lampsilis fasciola Wavyrayed Lampmussel Rafinesque X X X
Lampsilis ovata Pocketbook (Say) X X X
Lasmigona costata Flutedshell (Rafinesque) R
Medionidus conradicus Cumberland Moccasinshell (Lea) X X
Pleurobema oviforme Tennessee Clubshell (Conrad) X X
Pleurobema sp. cf. oviforme X X
Pleuronaia barnesiana Tennessee Pigtoe (Lea) X X X
Pleuronaia dolabelloides* Slabside Pearlymussel* (Lea) X
Villosa iris Rainbow (Lea) X X X
Villosa sp. cf. iris X X
Villosa vanuxemensis Mountain Creekshell (Lea) X X X
Total 14 7 14
A Visual inspection of specimen photographs provided by Carnegie Museum of Natural History revealed
that Ortmann likely collected Pleurobema sp. cf. oviforme and Villosa sp. cf. iris in addition
to P. oviforme and V. iris. Ortmann (1918) also reported Fusconaia cuneolus and Toxolasma lividum
Rafinesque (Purple Lilliput) from Pistol Creek, a tributary to Little River that confluences at rkm 8.2.
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Field-Site Description
The study area for this project was the Little River mainstem located in Blount
County, TN (Fig. 1). The Little River originates in Great Smoky Mountains National
Park (GSMNP) and flows northwest for ~95 rkm until its confluence with
Tennessee River. The Little River drains ~982 km2, of which ~65% is forested,
20% agricultural, 10% residential, 4% commercial, and 1% water or wetlands (TVA
2003). The Little River watershed is within 2 physiographic provinces: the Blue
Ridge occupying 649 km2 or ~66% of the upper watershed, and the Ridge and Valley
occupying 333 km2 or ~34% of the lower watershed. Transition between these
2 provinces occurs at approximately rkm 29.9. The headwaters of the Little River
are protected by GSMNP until rkm 56.0, contributing to excellent water quality in
its headwaters. The Little River has 3 intact low-head dams at rkm 54.1, 35.2, and
10.5, respectively. Immediately downstream of the third intact low-head dam, the
course of the Little River is inundated by the Fort Loudoun impoundment for 10.5
km before reaching the Tennessee River.
Methods
We qualitatively sampled live mussels during 2013 and 2014 at 18 sites in the
Little River mainstem based on ability to survey without scuba equipment and each
site having a minimum of a riffle, run, and pool (Fig. 1, Table 2). No tributaries
Figure 1. Sampling localities for mussels in the Little River, Blount County, TN, from 2013
through 2014. River km are shown for each site.
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were surveyed during this study because most are listed as water-quality impaired
by the Tennessee Department of Environment and Conservation (TDEC 2014a).
Sample sites were distributed across 41.5 rkm of the mainstem, with sites 1.4 to
3.9 kms apart. The upper 13 sites were located in the Blue Ridge Physiographic
Province, while the lower 5 sites were located in the Valley and Ridge Physiographic
Province. Each site was 200 m in length irrespective of stream width, and
we used a Nikon rangefinder to measure boundary extents of each site. Experienced
surveyors began at the downstream survey boundary, snorkeling or slowly walking
side-to-side (where too shallow to snorkel) in an upstream direction. We sampled
all surface-visible mussels and flipped some larger rocks to search underneath. We
recorded search time to estimate catch-per-unit-effort (CPUE). Mussels were identified
to species, enumerated, and measured to the nearest millimeter (mm) using
calipers; gender was recorded for sexually dimorphic species. We did not count
fresh dead shells except for Alasmidonta viridis (Slippershell Mussel), which was
represented by a single fresh dead specimen during our study and included in the
live mussels totals. We retained select mussels for genetic analyses and returned
all others to the substrate. Fresh dead and relic shells were placed in bags labeled
with site and date and deposited at the Parmalee Malacological Collection located
in McClung Museum at the University of Tennessee.
Results
An average of 10.5 person hours (h) was spent at each site, for a total of 189.5 h
for the entire survey of Little River (Table 3). During the survey, 3053 individuals
were found, representing 12 live species and 1 species obtained only as fresh-dead
Table 2. Locality information of sites sampled for mussels during this study in the Little River, Blount
County, TN, from 2013 through 2014.
Site name River mile River km Latitude Longitude
Lazy Daze Campground 34.2 55.0 35.67839 -83.71786
Wears Valley Road 33.3 53.6 35.68036 -83.73205
Webb Road 31.8 51.2 35.67807 -83.75499
Handicap Access 30.0 48.3 35.68006 -83.78287
Kinzel Springs 29.2 47.0 35.68473 -83.79350
Capshaw Branch 28.1 45.2 35.69740 -83.79805
Picnic Stop 26.5 42.6 35.70272 -83.81465
Foothills Parkway 25.0 40.2 35.71812 -83.81609
Walland 24.2 38.9 35.72551 -83.81806
Mystic Campground 22.9 36.9 35.73893 -83.82698
Below Melrose Dam 21.9 35.2 35.74978 -83.83699
Coulters Bridge 20.6 33.2 35.76372 -83.85268
Davis Ford 19.4 31.2 35.77712 -83.85373
US Route 411 17.2 27.7 35.78721 -83.88261
Above River Jons 14.8 23.8 35.79638 -83.88695
Brakebill Island 12.4 20.0 35.81029 -83.89973
Singleton Bend 10.4 16.7 35.81584 -83.92414
TN State Route 33 8.4 13.5 35.81964 -83.93701
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Table 3. Species and counts of live mussels sampled at sites in the Little River, Blount County, TN, from 2013 through 2014. * indicates federally endangered
species. + indicates survey in same locale as TVA survey; ‡ indicates sites in which Villosa sp. cf. iris was present, but we recognized it as V. iris at
the time of collection; FD = single fresh dead specimen.
River River Person Total Total
Site name mile km hours number species
Lazy Daze Campground 34.2 55.0 6.0 0 0
Wears Valley Road 33.3 53.6 6.0 10 10 1
Webb Road 31.8 51.2 12.0 49 3 6 358 416 4
Handicap Access ‡ 30.0 48.3 12.0 3 5 215 68 127 418 5
Kinzel Springs 29.2 47.0 15.0 FD 5 3 30 57 7 81 184 7
Capshaw Branch 28.1 45.2 11.5 7 13 21 56 202 299 5
Picnic Stop ‡ 26.5 42.6 7.0 3 55 35 93 3
Foothills Parkway 25.0 40.2 13.0 4 2 4 2 73 425 98 608 7
Walland 24.2 38.9 10.0 6 4 2 4 37 131 41 225 7
Mystic Campground 22.9 36.9 10.5 4 2 2 103 215 23 349 6
Below Melrose Dam 21.9 35.2 8.0 2 4 15 1 22 4
Coulters Bridge ‡ 20.6 33.2 12.0 14 30 1 3 58 70 1 177 7
Davis Ford 19.4 31.2 9.0 8 3 1 3 6 1 22 6
US Route 411 17.2 27.7 10.0 13 2 3 7 13 1 1 40 7
Above River Jons 14.8 23.8 11.0 5 7 5 6 34 4 4 1 66 8
Brakebill Island 12.4 20.0 15.5 1 1 10 1 13 3 29 6
Singleton Bend+ 10.4 16.7 11.0 1 7 14 1 2 11 3 1 40 8
TN State Route 33 8.4 13.5 10.0 11 6 1 2 32 2 1 55 7
Totals 189.5 1 7 19 106 9 53 11 319 164 4 522 857 981 3053 13
Alasmidonta viridis
Elliptio dilatata
Fusconaia cuneolus
Lampsilis fasciola
Lampsilis ovata
Medionidus conradicus
Pleurobema oviforme
P. sp. cf. oviforme
Pleuronaia barnesiana
Pleuronaia dolabelloides
Villosa iris
V. sp. cf. iris
Villosa vanuxemensis
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(Table 3). The CPUE per site ranged from 0 to 46.8 mussels/h and averaged 16.1
mussels/h. The most abundant species sampled during the survey, in order of relative
abundance, were: Villosa vanuxemensis (Mountain Creekshell; 32.1%), Villosa
sp. cf. iris (28.1%), Villosa iris (Rainbow; 17.1%), and Pleurobema sp. cf. oviforme
(10.5%). The remaining 8 species sampled live represented a combined 12.2% of
total relative abundance. Lasmigona costata (Flutedshell) was added to the fauna
from a relic shell, raising the total number of species sampled to 14. Two of these
species are listed as federally endangered, Fusconaia cuneolus (Finerayed Pigtoe)
and Pleuronaia dolabelloides (Slabside Pearlymussel), with the latter being a new
record for the Little River. Villosa sp. cf. iris was not recognized as distinct from
V. iris during the surveys at 3 sites (rkms 48.3, 42.6, and 33.2), but visual inspection
of photographs for sampled specimens suggests it was present at these sites;
thus, abundances of each of these 2 species at these 3 sites are unknown. Based
on field-level observations of morphological differences, we performed molecular
genetic analyses and concluded that there is a putative taxon separate from V. iris
in the Little River (Schilling et al. 2015). Lasmigona costata was collected at rkm
23.8 during preliminary reconnaissance to locate suitable sampling localities; this
individual was not included in results for the survey, as it was obtained without
CPUE estimates, but is listed as collected during the year of the surveys in Table 1.
A total of 319 individuals of Pleurobema sp. cf. oviforme were sampled at 9
sites; 215 individuals were sampled at 1 site, rkm 48.3. Shell lengths of live individuals
ranged from 17 mm to 100 mm and averaged 60.6 mm (Table 4); however,
an individual was collected for additional analyses outside of the survey that had
a length of 104 mm. Minimum length of P. sp. cf. oviforme typically increased at
collection sites downstream from the Townsend, TN, area.
Discussion
Mussel sampling
Historically, 14 mussel species have been recorded in the Little River drainage.
Excluding the relic shell and the putative new species, we sampled 11 of those 14
mussel species. Mussels were patchily distributed at sites in Little River, with the
highest mussel abundances being found in areas of the stream with stable substrate,
including stream edges and areas adjacent to islands containing Justicia spp. (water
willow). Mussels were occasionally located away from these areas, but in most
instances they typically were found between or under large rocks with interstitial
spaces. Any future studies aimed at determining quantitative abundances using
techniques such as quadrat sampling should be aware of the patchy mussel distribution
in this river.
Four federally endangered mussel species are now known from Little River,
including Cumberlandia monodonta (Spectaclecase), Epioblasma triquetra (Snuffbox),
Fusconaia cuneolus, and Pleuronaia dolabelloides. Pleuronaia dolabelloides
had not been documented in Little River until our survey. While the minimum size
sampled was 62 mm, 2 of the 4 individuals sampled during this survey were gravid,
suggesting that reproduction and possibly recruitment may be occurring. This
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Table 4. Mean length and range of lengths (mm) of each mussel species by site sampled in the Little River, Blount County, TN, from 2013 to 2014. - indicates
none or too few specimens to analyze; FD = fresh dead specimen only.
River km
55.0 53.6 51.2 48.3 46.8 45.2 42.6 41.0 38.9
Alasmidonta viridis - - - - FD - - - -
- - - - - - - - -
Fusconaia cuneolus - - - - - - - - -
- - - - - - - - -
Elliptio dilatata - - - - - - - - -
- - - - - - - - -
Lampsilis fasciola - - - 59 50 63 59 55 54
- - - (45–69) (26–71) (41–80) (53–65) (37–64) (29–78)
Lampsilis ovata - - - - - - - - -
- - - - - - - - -
Medionidus conradicus - - - 40 48 - - 53 43
- - - (35–56) (38–53) - - (48–57) (36–46)
Pleurobema oviforme - - - - - - - - -
- - - - - - - - -
Pleurobema sp. cf. oviforme - - 47 65 53 56 - 49 64
- - (21–88) (29–100) (17–77) (32–85) - (39–57) (63–64)
Pleuronaia barnesiana - - - - - - - 53 57
- - - - - - - (44–62) (46–68)
Pleuronaia dolabelloides - - - - - - - - -
- - - - - - - - -
Villosa iris - - 42 40 40 46 38 39 46
- - (30–53) (20–60) (15–73) (30–63) (15–52) (15–58) (22–63)
Villosa sp. cf. iris - - 39 - 42 41 - 38 37
- - (30–56) - (34–48) (21–57) - (11–57) (12–56)
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Table 4, continued.
River km
55.0 53.6 51.2 48.3 46.8 45.2 42.6 41.0 38.9
Villosa vanuxemensis - 39 35 40 38 39 39 38 39
- (33–54) (10–55) (14–55) (14–56) (15–58) (20–49) (11–58) (24–55)
Alasmidonta viridis - - - - - - - - -
- - - - - - - - -
Fusconaia cuneolus - - - - - - 34 54 48
- - - - - - - (37–72) (24–70)
Elliptio dilatata - - - - - 73 57 76 -
- - - - - (34–119) - - -
Lampsilis fasciola 56 56 59 54 54 64 50 56 49
(39–72) (44–67) (32–88) (29–78) (36–68) (51–72) (30–60) (31–74) (38–67)
Lampsilis ovata - - - - 109 104 - 78 97
- - - - (105-113) (39-124) - - -
Medionidus conradicus 37 - 40 43 44 - 43 - -
(28–45) - (18–53) (40–48) (41–46) - - - -
Pleurobema oviforme - - 66 - - 62 - 42 41
- - - - - (42–78) - (36–48) (34–48)
Pleurobema sp. cf. oviforme 62 - 72 68 - - - - -
(57–66) - (66–80) - - - - - -
Pleuronaia barnesiana - - 59 52 53 47 37 45 38
- - (24–87) (48–54) (36–73) (23–79) (18–55) (25–60) (19–58)
Pleuronaia dolabelloides - - - - - 75 - - -
- - - - - (62–86) - - -
Villosa iris 40 39 48 42 50 45 39 50 38
(19–59) (31–46) (20–66) (25–55) (31–63) (43–48) (23–63) (44–57) (28–48)
Villosa sp. cf. iris 34 32 - 38 52 - - - -
(12–53) (20–46) - - - - - - -
Villosa vanuxemensis 34 31 39 - 48 67 - 39 37
(15–52) - - - - - - - -
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observation adds a new river of occurrence for the species, which could assist recovery
efforts aimed to downlist or delist the species. This species may also occur
in lower reaches of the Little River that were not included in this survey. Fusconaia
cuneolus previously has been documented in the Little River by TVA (Hickman and
Harned 1981), but due to lack of sampling in Little River over the last few decades,
its range and occurrence in the river was unknown; their study documented 1 individual
F. cuneolus at rkm 15.4. During our survey, 19 individuals of this species were
sampled at 3 sites from rkm 20.0 to 13.5. Shell lengths ranged from 24 mm to 72 mm
and averaged 49.2 mm, which indicates multiple year-classes and recent recruitment.
We did not find Cumberlandia monodonta or Epioblasma triquetra during the survey
of the Little River. Both species were recorded over a century ago by Ortmann (1918)
only from the lower-most portions of the Little River in Knox County that are now inundated.
It is possible that C. monodonta persists in unsampled lower reaches of the
river if appropriate habitat occurs (large slab boulders or bedrock shelves); however,
E.triquetra is likely extirpated from Little River.
In addition to the 2 federally listed mussels, several other extant species from
Little River are considered imperiled globally (Williams et al. 2008). These species
include Alasmidonta viridis, Lampsilis ovata (Pocketbook), Medionidus conradicus
(Cumberland Moccasinshell), Pleurobema oviforme (Tennessee Clubshell),
Pleuronaia barnesiana (Tennessee Pigtoe), and Villosa vanuxemensis. Thus, about
70% of the currently recognized mussel species extant in Little River are imperiled;
this proportion excludes the 2 putative new species.
Two of the 3 sites contained individuals that were field-identified by 3 biologists
as Fusconaia cor (Conrad) (Shiny Pigtoe), but molecular genetic analyses using the
mitochondrial gene ND1 and the nuclear gene ITS1 determined that all individuals
were F. cuneolus (Schilling 2015). Misidentification of multiple individuals of
F. cuneolus as F. cor suggests that either contemporary morphological identification
characters are inadequate, or perhaps that introgression and/or hybridization has occurred
between these 2 species and was not detected at the molecular markers used.
Ortmann (1918) reported Actinonaias pectorosa (Pheasantshell) from the Little
River. This imperiled species is known only from this single record of 1 specimen.
Steve Ahlstedt, retired United States Geological Survey malacologist, examined
the specimen and noted that it resembles Lampsilis fasciola (Wavyrayed Lampmussel)
and therefore, it could be misidentified (S. Ahlstedt, Knoxville, TN, 13
December 2015 pers. comm.).
The highest densities of Pleurobema sp. cf. oviforme occurred upstream of Chilhowie
Mountain toward the lower-gradient section of the river near Townsend, TN.
Live individuals were sampled at sites in a 20-rkm reach from rkm 51.2 to rkm 31.2.
Populations of P. sp. cf. oviforme and Pleurobema oviforme overlapped for only
2.0 km, with P. sp. cf. oviforme occurring in the upper portions, and P. oviforme
occurring in the lower portions. Failure to obtain individuals of P. sp. cf. oviforme
at sites sampled outside of Little River drainage coupled with no mention of this
species outside of the drainage in the historical literature indicates that P. sp. cf.
oviforme may be endemic to Little River. Schilling (2015) recorded the maximum
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size of P. sp. cf. oviforme as 104 mm, while he recorded the largest size of P. oviforme
as 94 mm from North Fork Holston River, Smyth County, VA, indicating that
maximum size differences between the 2 species may exist.
The Villosa sp. cf. iris were sampled in a 23.5-rkm reach from rkm 51.2 to rkm
27.7, with several smaller-sized individuals less than 30 mm observed (Table 4), indicating
recent recruitment of this putative species. This species closely resembles V. iris
and therefore was not recognized in past surveys in the drainage. The maximum
size of V. iris sampled during the survey was 73 mm, while the maximum size of
V. sp. cf. iris was 57 mm. While V. iris occurred broadly throughout our survey
sites, the largest densities of V. sp. cf. iris occurred from rkm 25.5 to rkm 22.9.
Future surveys to document species’ ranges outside of Little River should be cognizant
of cryptic species such as P. sp. cf. oviforme and V. sp. cf. iris.
Little River water quality
Generally, mussel densities declined downstream from the confluence of
Ellejoy Creek just upstream of Davis Ford (rkm 31.2). Areas upstream of this confluence
contained more mussels based on higher CPUE metrics; fine sediment in
the substrate also appeared to be lower upstream of the creek’s confluence with
Little River. Little River watershed quality is of concern; pristine waters originating
from the GSMNP are degraded downstream towards its confluence with the
Tennessee River. For example, Jett (2010) quantitatively documented a drastic increase
in turbidity after the entry of water from Ellejoy Creek relative to upstream
reaches. TVA (2003) estimated that the Ellejoy Creek drainage has the most
linear meters of eroding stream bank and the most eroding hectares of unpaved
roads within the Little River watershed. While Hart (2006) did not find significant
differences in total suspended solids from headwater to downstream sites,
she suspected that solids remained suspended in the water column in upstream
or higher-gradient areas and were being deposited from the water column in the
downstream, lower-gradient areas of the river. Hart (2006) also noted high turbidity
levels in Ellejoy Creek, but suspected the sediments were deposited from
the water column before reaching her next mainstem site of Little River. While
we did not collect quantitative data on sediment attributes, we noticed higher
substrate instability, increased fine sediment, and higher embeddedness during
mussel surveys in 2013 and 2014 in lower reaches of Little River downstream of
Ellejoy Creek. The additional deposited sediments could be negatively impacting
the benthic communities in lower reaches. Thus, more analyses are needed to
understand sediment impacts of Ellejoy Creek and other tributaries on the water
quality and aquatic fauna of the Little River.
The river topologies and historical mussel faunas of Little River and its neighbor,
Little Pigeon River, are similar. However, Little Pigeon River mussels have
declined in its West Prong due to a range of anthropogenic impacts of commercial,
industrial, and residential development. Most notable was a spill in 2011 that resulted
in an estimated 1.5–3.2 million gallons of raw or treated sewage entering
the river (Donovan 2011). Previous elevated levels of fecal coliform in 1993 led
to warnings by the Tennessee Department of Environment and Conservation for
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citizens to avoid contact with water in the river (TDEC 2014b). No recent mussel
surveys exist for the West Prong Little Pigeon River or sections downstream of
this area due to these advisories; however, large mussel declines were observed
in the 1980s and 1990s (G. Dinkins, Curator of Malacology and Natural History,
McClung Museum of Natural History and Culture, University of Tennessee, Knoxville,
TN, 12 January 2016 pers. comm.).
Summary
The Little River has a unique and imperiled fauna with 14 extant species, of
which 2 are federally endangered species (F. cuneolus and Pleuronaia dolabelloides),
2 are putative new species (Pleurobema sp. cf. oviforme and V. sp. cf. iris),
and several other imperiled mussels. Due to the maintenance of excellent water
quality in upstream areas of the Little River, the waterway should be the focus for
future conservation efforts in order to avoid negative impacts observed in the West
Prong Little Pigeon and other nearby systems. Previous mussel surveys of Little
River did not document Lasmigona costata, Pleuronaia dolabelloides, Pleurobema
sp. cf. oviforme, or V. sp. cf. iris. Brief survey attempts during this study did not
locate additional populations of P. sp. cf. oviforme or V. sp. cf. iris outside of the
Little River drainage. The similar-looking shells of mussel species in the genera
Fusconaia, Pleurobema, and Pleuronaia have led to inconsistent identification and
estimates of species abundance in Little River and throughout the Tennessee River
valley (Schilling 2015). Future conservation efforts should focus on intensive spatial
sampling in the Tennessee River basin and additional molecular genetic characterization
in order to determine cryptic biodiversity and the conservation status
of putative species.
Acknowledgments
We are grateful to Bill Reeves and Don Hubbs of the Tennessee Wildlife Resources
Agency (TWRA) for financial support of this project. We especially thank Jon Mollish for
his assistance with field work and providing valuable resources to complete this project. We
also appreciate Hugh Faust’s willingness to travel to sites and assist with field sampling for
this project. We thank Bob Butler of United States Fish and Wildlife Service, Bobby Brown
and Allen Pyburn of TWRA, Chuck Howard of Tennessee Valley Authority, and Jen Rogers of
Virginia Tech for assistance with field sampling. Gerry Dinkins and Steve Ahlstedt contributed
valuable knowledge to complete sampling. We also are indebted to Tim Pearce of Carnegie
Museum of Natural History for photographing and lending the specimen of Actinonaias
pectorosa. Support for E.M. Hallerman’s participation in this work was provided in part by
the Virginia Agricultural Experiment Station and the Hatch Program of the National Institute
of Food and Agriculture, US Department of Agriculture. The views expressed in this article
are the authors and do not necessarily represent those of the US Fish and Wildlife Service.
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