Status and Life-history Aspects of Villosa constricta (Conrad 1838) (Notched Rainbow), in the Upper Neuse River Basin, North Carolina
Chris B. Eads, Arthur E. Bogan, and Jay F. Levine
Southeastern Naturalist, Volume 5, Number 4 (2006): 649–660
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2006 SOUTHEASTERN NATURALIST 5(4):649–660
Status and Life-history Aspects of Villosa constricta
(Conrad 1838) (Notched Rainbow), in the Upper Neuse
River Basin, North Carolina
Chris B. Eads1,*, Arthur E. Bogan2, and Jay F. Levine1
Abstract - We report the findings of stream-survey data, a length-at-age study, and
host-fish determination for Villosa constricta (notched rainbow). Visual surveys
were done for freshwater mussels at 44 bridge crossings in the upper Neuse River
basin in North Carolina. Three surveyors, each searching a 1-m wide lane, covered a
600-m long stream reach at each site. All mussels found were identified to species
and measured, and females were checked for gravidity. Of the 24 sites where V.
constricta occurred, the median number found was 3.5 (range = 1–54). We cut thinsections
of 71 individual shells collected from middens at 1 survey site and counted
growth lines to determine mussel age. Shell ages ranged from 3 to 14 years. Lab trials
determined that Etheostoma flabellare (fantail darter) served as a suitable host for
Villosa constricta (Conrad) (notched rainbow; Bivalvia:Unionidae)
ranges along the mid-Atlantic slope from the Catawba River basin in North
Carolina north to the James River basin in Virginia (Johnson 1970). It
primarily occurs in coarse sand in areas with some current, with a brooding
season from August to June (Johnson 1970), and is listed as a species of
special concern (Williams et al. 1993). Other crucial life-history information
is relatively unknown. The type locality for this species is the North River in
Rockbridge County, VA (Bogan 2002).
The national strategy for the conservation of freshwater mussels lists
answering basic biology and ecology questions as a high priority to protect
imperiled species (NNMCC 1998). In addition to determining the status of
this species in the upper Neuse River basin, we sought to further study
aspects of its basic life history. Watters et al. (1999) used lab trials to report
several potential hosts for this species; however, a majority of those reported
hosts do not co-occur with Villosa constricta, and transformation success
was limited with not more than 5 juveniles produced from any single fish
species. One of our objectives was to conduct host-fish trials to enhance our
understanding of V. constricta life history and facilitate captive propagation.
Also, discovery of muskrat middens containing a large number of shells of
this species presented a unique opportunity to gain valuable life-history
information on this species such as longevity and length-at-age data.
1Department of Population Health and Pathobiology, College of Veterinary Medicine,
North Carolina State University, 4700 Hillsborough Street, Raleigh, NC 27606.
2North Carolina State Museum of Natural Sciences, 4301 Reedy Creek Road, Raleigh,
NC 27607. *Corresponding author - Chris_Eads@ncsu.edu.
650 Southeastern Naturalist Vol. 5, No. 4
The survey study area was defined as the Neuse River basin above Falls
Lake (Fig. 1). The 1686-km2 region covers portions of Orange, Durham,
Person, Granville, and Wake counties in North Carolina. The main drainages
in the area are the Eno, Little, and Flat River watersheds, but several other
smaller watersheds feed directly into Falls Lake from Granville and Wake
Figure 1. Upper Neuse River basin study area.
2006 C.B. Eads, A.E. Bogan, and J.F. Levine 651
counties. The geology in this area results in a variety of stream types from
rocky to sandy, and a diversity of stream-channel types are represented in
this relatively small portion of the Piedmont. Durham, Hillsboro,
Creedmoor, and Butner are the primary municipalities in the region, with
Durham being the largest (population = 190,000). The dominant land uses
within the sub-basin included forest (61%), urban (16%), and agriculture
(18%). Various wetland types comprised 4% of the land cover (EPA 2000).
With the exception of two sites along the mainstem Eno River where the
setting was somewhat more urban, mussel-survey sites were restricted to
rural areas where stream riparian zones are well buffered by forest and
agricultural use was not intensive.
A total of 44 study sites were selected to cover the study area and
surveyed from 24 April–21 August 2001 (Fig. 2). At each site, 3 surveyors
each searched 1-m wide lanes (one next to each bank and one in the center of
the stream) using view scopes and snorkeling to visually locate mussels.
Surveyors covered the two 300-m stream reaches immediately upstream and
downstream of the road crossing as well as the area under the crossing
structure. To maximize consistency through time and between surveyors,
only surface visual searches were done, and no excavation or rock flipping
was used to locate mussels. Tactile searching was used as necessary when
murky water, debris piles, or undercut banks made visual searches difficult;
Figure 2. Map of 2001 study area and 44 survey sites in the upper Neuse River basin.
Solid circles indicate sites containing Villosa constricta, and open circles represent
sites where the species was not found.
652 Southeastern Naturalist Vol. 5, No. 4
however, only mussels felt on the sediment surface were taken. We collected
all mussels found in the three lanes, and no mussels were included in the
survey that fell outside of a surveyor’s measured lane. All but 2 sites were
completed within the same day. Those 2 sites were each completed in 2
consecutive days, and no substantial weather changes or rain occurred between
days. We identified all mussels and recorded length, gender, and
gravidity state for all sexually dimorphic species.
Age and growth
A total of 71 (47 male, 24 female) Villosa constricta shells were collected
for age and growth studies from middens at the West Fork Eno River
at the most downstream crossing of SR 1004 in Orange County. We measured
the length of each shell and assigned them unique identification
numbers. Using a Buehler® low-speed, precision saw, a cut was made
through both valves of each shell along the posterior ridge, creating four
shell pieces for each individual. We then used an epoxy resin to adhere the
cut side of the four resultant shell pieces to glass microscope slides. When
the epoxy had cured, a final cut was made through the adhered shells to
create thin-sections with a thickness of 500 m attached to the glass slides
(Fig. 3). We then determined age by counting internal growth lines using a
stereomicroscope (Neves and Moyer 1988). Final age for a mussel was
determined by examining all four thin-sections. In most shells, the first year
of growth had been eroded away, so one year was added to the age of those
shells eroded in the area where the first year’s growth line was typically
located (Hanlon and Levine 2004). Lines not originating at the umbo or
extending to the periostracum were assumed to be false annuli and not
counted (Neves and Moyer 1988).
Three fish-host trials were conducted in the laboratory (Zale and Neves
1982) to determine a suitable host for Villosa constricta. We collected 5
gravid females on 11 May 2004 from Deep Creek in Person County and 13
fish species by seine and backpack electrofisher from Richland Creek in
Wake County, NC. On 12 May 2004, glochidia were extracted from mussels
by flushing the marsupium with a water-filled syringe and tested for
viability by exposure to a solution of NaCl. Glochidia were 100% viable
according to this test. Fish were put into a tank containing 31 L of water at
20 ºC, which was aerated vigorously. The glochidia were then dumped into
the tank with the fish and stirred periodically to keep them in suspension.
We checked the gills of some fish for infestation periodically throughout
the exposure, and removed the fish from the glochidial suspension after 30
minutes. Fish were then maintained in 38-L aquaria at 20–22 ºC and fed
either commercial pellet food, frozen blood worms, or live earthworms.
Each tank contained only a single species of fish. Tanks were then siphoned
every 2–3 days through a 105-mm-mesh sieve, and the trial ended
on 21 June 2004 (41 days post-infestation).
2006 C.B. Eads, A.E. Bogan, and J.F. Levine 653
For the second trial, one gravid female Villosa constricta was collected
in March 2005 from the Little River in Randolph County in the Yadkin-Pee
Dee River basin and was maintained in a laboratory tank chilled to 6 ºC until
the trial began. Using a backpack electrofisher, a total of 16 species of fish
was collected from Horse Creek in Wake County, NC (Neuse basin) in
March 2004 to be used in the trial. Fish were maintained in the laboratory at
18 ºC and fed regularly. On 19 April 2004, glochidia were extracted from the
mussel by flushing the marsupium with a water-filled syringe. We anesthetized
the fish with MS-222, and pipetted glochidia directly onto their gills.
The fish were placed in a recovery tank and then moved back to their
individual aquaria where they were fed daily. Individual aquaria contained
only a single species. Tanks were siphoned every 2–3 days for 27 days postinfestation
to check for live transformed juveniles.
The third trial used 7 gravid V. constricta collected from the North Fork
Little River in Orange County, NC in April 2005 and fish collected from
Upper Barton Creek in Wake County, NC on 18 May 2005. Gravid mussels
were maintained in a tank in the laboratory at 6 ºC until the trial began. On
18 May 2005, glochidia were extracted from the females and directly
pipetted onto one gill of 123 Etheostoma flabellare (Rafinesque) (fantail
darters) and 6 Percina roanoka (Jordan and Jenkins in Jordan) (Roanoke
darters) as described in the second trial. Fish were then maintained in 45-L
tanks at 18 ºC, fed regularly, and checked routinely for transformed juveniles
until 43 days post-infestation.
We found Villosa constricta at 24 of the 44 sites surveyed (Fig. 2), and
numbers found ranged from 1 to 54 (Table 1), totaling 190 individuals (143
males, 47 females) across all sites. The median number of individuals found at
sites where the mussel occurred was 3.5 (quartiles = 1.75 and 8.25). This
species tended to occur in coarse sand and sand/gravel mixtures in areas with
some current. The surveyor in the middle of the stream found 114 individuals
Figure 3. Left and right
valve of an individual
Villosa constricta cut
along the posterior ridge.
The four thin-sections
created from each individual
were adhered to
654 Southeastern Naturalist Vol. 5, No. 4
compared to only 41 along the left bank and 35 along the right bank. The sites
where the greatest number of individuals were found (Deep Creek, and the
North Fork Little River) were characterized by stable and consolidated sand,
gravel, and cobble mixes across the entire channel. Gravid females were
found on 4 May, 11 June, 12 July, and 20 August (Table 1). Mean length of all
males (42.9 ± 6.8 mm) was significantly larger than that of females (35.5 ± 5.8
mm) (t-test, p < 0.001).
Age and growth
The collected shells ranged in age from 3–14 years (Fig. 4), with a
median age of 5 (quartiles = 4 and 8). Shells that were three years of age
clearly exhibited sexual dimorphism. Age in female shells collected was
fairly evenly distributed from age 3 to age 10 with a median age of 7
(quartiles = 4.75 and 9.25); however, male shells were much more abundant
at ages 3–5 with a median age of 5 (quartiles = 4 and 7) (Fig. 5). Males and
females were closest in size at the youngest ages, but males grew at a faster
rate than females. The largest and oldest shell found in the midden was a 14-
year-old male measuring 54 mm in length that looked quite old and eroded.
Table 1. Number of Villosa constricta found, gravidity, and mean length at 24 sites where the
species occurred in surveys of 44 sites in the upper Neuse River basin in North Carolina during
2001. M = # of males found, F = # of females found, and T = total # found.
% of Mean
Sub- Road Date females length (mm)
basin Stream crossing surveyed M F T as gravid (min, max)
Eno Stroud’s Cr. SR 1002 18 May 2 0 2 - 43 (42, 44)
Eno Stroud’s Cr. SR 1555 24 May 0 1 1 0 54 (54, 54)
Eno McGowan Cr. SR 1338 30 May 3 0 3 - 44 (43, 47)
Eno Eno R. SR 1336 27 June 3 2 5 0 39 (25, 49)
Eno W. Fork Eno R. SR 1004 3 July 1 0 1 - 61 (61, 61)
Eno E Fork Eno R. SR 1332 6 July 1 0 1 - 48 (48, 48)
Eno Sevenmile Cr. SR 1120 12 August 1 1 2 0 55 (55, 55)
Eno W. Fork Eno R. SR 1004 20 August 5 1 6 100 38 (27, 53)
Eno Eno R. SR 1561 21 August 2 0 2 - 54 (42, 65)
Flat Deep Cr. SR 1723 4 May 0 4 4 50 42 (39, 44)
Flat Deep Cr. SR 1734 11 June 38 16 54 18.8 38 (28, 52)
Flat S. Flat R. SR 1125 20 June 10 3 13 0 44 (33, 54)
Flat Flat R. SR 1614 28 June 1 2 3 0 39 (31, 47)
Flat S. Flat R. SR 1123 5 July 5 1 6 - 46 (38, 53)
Flat S. Flat R. US 501 18 July 12 4 16 0 38 (29, 46)
Flat N. Flat R. SR 1715 25 July 1 0 1 - 33 (33, 33)
Flat Flat R. SR 1771 9 August 1 0 1 - 41 (41, 41)
Little Forrest Cr. SR 1548 24 April 1 0 1 - 41 (41, 41)
Little S. Fork Little R. SR 1538 25 June 6 0 6 - 37 (31, 44)
Little S. Fork Little R. NC 157 26 June 10 1 11 0 54 (48, 60)
Little N. Fork Little R. SR 1538 12 July 19 9 28 12.5 42 (24, 55)
Little S. Fork Little R. NC 57 19 July 7 2 9 0 46 (41, 52)
Little S. Fork Little R. SR 1540 23 July 3 0 3 - 46 (38, 50)
Little S. Fork Little R. SR 1461 14 August 3 0 3 - 54 (48, 60)
2006 C.B. Eads, A.E. Bogan, and J.F. Levine 655
Trial 1 yielded only two live individuals, which transformed on
Lepomis cyanellus (Rafinesque) (green sunfish) (Table 2). This fish species
was used again in Trial 2 along with other Lepomis spp., but that
Figure 4. Length-at-age for male and female Villosa constricta in the West Fork of
the Eno River in Orange County.
Figure 5. Age-frequency distribution of male and female Villosa constricta shells
found in the West Fork of the Eno River in Orange County.
656 Southeastern Naturalist Vol. 5, No. 4
infestation produced juvenile mussels only from the fantail darters
(Table 3). A total of 14 juveniles were produced by 5 Etheostoma
flabellare with a transformation time of 22 (n = 13) and 26 (n = 1) days,
so we decided to focus our efforts in Trial 3 on this darter species. By
hand-infesting one gill each on 123 E. flabellare, we produced a total of
192 juvenile mussels with a mean transformation time of 35.9 ± 4.3 days
(SD) (Range = 21–44 days) at 18 ºC. The only other species in that trial,
Percina roanoka, did not produce any transformed mussels.
Table 2. Number of fish infested with Villosa constricta and the number of live juveniles
produced during Trial 1.
# of days to juvenile
Fish species Fish species # of fish complete mussels
(common name) (scientific name) exposed metamorphosis recovered
Bluegill L. macrochirus 6 n/a 0
Bluehead chub Nocomis leptocephalus 6 n/a 0
Fantail darter E. flabellare 5 n/a 0
Flat bullhead Ameiurus platycephalus 2 n/a 0
Green sunfish Lepomis cyanellus 8 22 2
Johnny darter Etheostoma nigrum 5 n/a 0
Largemouth bass Micropterus salmoides 3 n/a 0
Margined madtom Noturus insignis 8 n/a 0
Northern hogsucker Hypentelium nigricans 3 n/a 0
Redbreast sunfish L. auritus 2 n/a 0
Swallowtail shiner Notropis procne 6 n/a 0
White shiner Luxilus albeolus 5 n/a 0
Table 3. Number of fish infested with Villosa constricta and the number live juveniles produced
during Trial 2.
# of days to juvenile
Fish species Fish species # of fish complete mussels
(common name) (scientific name) exposed metamorphosis recovered
Bluegill Lepomis macrochirus 2 n/a 0
Bluehead chub Nocomis leptocephalus 3 n/a 0
Fantail darter Etheostoma flabellare 4 22–26 14
Flat bullhead Ameiurus platycephalus 1 n/a 0
Glassy darter Etheostoma vitreum 1 n/a 0
Green sunfish Lepomis cyanellus 2 n/a 0
Largemouth bass Micropterus salmoides 4 n/a 0
Margined madtom Noturus insignis 3 n/a 0
Northern hogsucker Hypentelium nigricans 2 n/a 0
Notchlip redhorse Moxostoma collapsum 4 n/a 0
Redbreast sunfish Lepomis auritus 1 n/a 0
Roanoke darter Percina roanoka 1 n/a 0
Satinfin shiner Cyprinella analostana 5 n/a 0
Swallowtail shiner Notropis procne 1 n/a 0
Warmouth Lepomis gullosus 1 n/a 0
White shiner Luxilus albeolus 4 n/a 0
2006 C.B. Eads, A.E. Bogan, and J.F. Levine 657
According to our surveys, this mussel was widespread across the study
area and was the second-most abundant species next to Elliptio complanata
(Lightfoot) in the Upper Neuse basin; however, rarely was it locally abundant.
Despite surveying 600 m of stream length at each site, we found more
than 10 individuals at only 5 sites and young individuals less than 40-mm
long at only 12 sites. Of those 12 sites containing only larger Villosa
constricta, only 1 of them had more than 3 individuals. Although growth
rates may likely differ between sites, our age and growth data showed that
the average males of this species are likely 7 years old before they reach 40
mm in length. The lack of individuals under 40 mm indicates that multiple
year classes are missing in areas where the species is sparse (i.e., lack of
In summary, there are few relatively healthy populations in the area
that are consistently experiencing recruitment. Those sites with the
healthiest populations were in highly stable channels with riffle-run complexes.
By contrast, sites where the species was not found tended to be
characterized by unstable shifting substrates. Mussels require stable substrates
to persist in streams (Di Maio and Corkum 1995, Johnson and
Brown 2000, Strayer 1999), but many of the streams in the upper Neuse
basin are highly incised and lack the instream refugia that unionids require.
Although much of the study area is currently forested and streams
are generally well buffered, the habitat suffers from past land use and
subsequent stream degradation (Trimble 1974). Many other mussel species
in North Carolina are rarer than Villosa constricta, yet even this
species of special concern, was rarely abundant at individual sites. Our
survey findings serve to emphasize the importance of protecting unspoiled
streams from further development to prevent the disappearance of
rare species that depend on high quality habitats.
Overall, we only found 7 gravid females during the 2001 surveys. This
was largely due to the fact that Villosa constricta was most abundant at sites
surveyed at the end of the brooding season. The single individual we found
gravid in July was fully gravid and likely just late in releasing its glochidia
compared to the several other females found at the site. According to
Johnson (1970), the brooding season begins in August and ends in June, so
the individual found on 20 August was likely at the beginning of the next
Age and growth
Thin-sectioning is an effective means of estimating the age of freshwater
mussels (Neves and Moyer 1988). In this study, female Villosa constricta
appear closest in size to males at age 3 (the youngest shells found), but over
time, males grow at a faster rate. This trend has been documented in other
Lampsilines (Hanlon and Levine 2004, Rogers et al. 2001) and may be due to
658 Southeastern Naturalist Vol. 5, No. 4
females investing more energy into brooding rather than into shell growth.
Overall, the male:female sex ratios were 2:1 in the middens. The abundance of
males in shell middens was primarily due to the year classes aged 3 to 5, where
males outnumbered females 3:1. Older mussels in middens had sex ratios
closer to 1:1. Possible reasons why more young mussels were male include an
actual higher number of males in certain year classes, differences in behavior
at those ages resulting in increased predation of males, or delayed maturity of
females causing their shells to appear more like that of a male. We clearly saw
sexual dimorphism in age-3 shells, indicating that this species may be sexually
mature at this age. Toxolasma pullus (Conrad) (Savannah lilliput),
another Lampsiline from the North Carolina piedmont, was sexually dimorphic
at age three (Hanlon and Levine 2004), and Lampsilis cardium
(Rafinesque), Lampsilis fasciola (Rafinesque), and Villosa iris (I. Lea) have
been shown to spawn and become gravid at age 3+ in captivity (James B.
Layzer, Tennessee Technological University, Cookeville, TN, pers. comm.).
However, perhaps some individuals of the species may mature at a slower rate
while not exhibiting the female shell form until after age three. If so, this could
cause misidentification of the sex of younger shells and an incorrectly skewed
male:female ratio in these year classes.
The oldest shell in this study was estimated to be 14 years of age, and it
appeared quite old and eroded. Of the 190 live Villosa constricta seen in our
surveys of the upper Neuse basin, only 10 individuals (5.3%) were larger
than this mussel. We suspect few mussels of this species live much longer
than this. Although some freshwater mussel species may be extremely longlived
(Ziuganov et al. 2000), V. constricta appears to live less than two
decades in this area. This appears to be the case with other small Lampsilines
in coastal drainages in North Carolina (Hanlon and Levine 2004). This study
demonstrates that useful life-history data important to species management
can be garnered from shell middens.
Additional testing was needed to determine the host(s) this species actually
uses for natural recruitment to occur. We used a batch-infestation
method in the first trial in an attempt to expose each fish to the same
concentration of glochidia; however, the larvae were likely too dilute in the
exposure tank for sufficient infection of the fishes’ gills. The lone producer
of juvenile mussels (Lepomis cyanellus) in the first trial was retested by
hand infestation and found not to support metamorphosis. Often when one
species of Lepomis is found to serve as a host of a given mussel species,
congeners will also serve as hosts for that species (C.B. Eads, unpubl. data;
Fuller 1974; Jenkinson 1982). We used 16 individuals of the genus Lepomis
in Trial 1 and 6 individuals in Trial 2, yet only 2 live juveniles were
produced. Watters et al. (1999) used a total of 19 fish representing 4 species
of this genus and also had poor transformation rates (total of 3 juvenile
mussels). We conclude that Lepomis are poor hosts and would not recommend
them for propagation of Villosa constricta.
2006 C.B. Eads, A.E. Bogan, and J.F. Levine 659
Both the second and third trials indicated that Etheostoma flabellare is a
suitable host for this species; however this species is rare in the Cape Fear
River basin (Menhinick 1991) where Villosa constricta is abundant. So there
is likely another natural host for this species. Since Etheostoma nigrum
(Rafinesque) (johnny darter), was only used in our initial trial that was
unsuccessful, we believe additional trials with this species and its close
relative, Etheostoma olmstedi (Storer) (tessellated darter), should be conducted
to determine viable hosts in the Cape Fear basin. Etheostoma
olmstedi was one of the hosts reported by Watters et al. (1999) that does cooccur
with V. constricta.
Our knowledge of the basic biology of freshwater mussels is still markedly
deficient—particularly in the Atlantic Slope, where few life-history studies
have been conducted. This study represents one step towards understanding
these species, but additional work is needed to: 1) refine our understanding of
freshwater mussel reproductive strategies; 2) develop a clear understanding
of freshwater mussel diets, growth, and metabolism; 3) assess the effects of
anthropogenic activity and environmental perturbation on population health,
survival, and abundance; 4) clarify these species’ role in sustaining the health
of freshwater ecosystems; and 5) define the conservation measures that
support the stewardship of freshwater mussel populations.
This study was made possible by funds from the North Carolina Department of
Transportation. We thank Chris Wood, Heather Boyette, April Lee, and Leroy
Humphries for assisting with mussel surveys. Heather also processed and prepared
thin-sections of the shells. John Barr, Paul Hubert, Joshua Johnson, and Erin
Schubert assisted with host-fish trials. We also thank all reviewers of this manuscript
for their helpful comments.
Bogan, A.E. 2002. Workbook and Key to the Freshwater Bivalves of North Carolina.
North Carolina Museum of Natural Sciences, Raleigh, NC. 101 pp., 10
Di Maio, J., and L.D. Corkum. 1995. Relationship between the spatial distribution of
freshwater mussels (Bivalvia: Unionidae) and the hydrological variability of
rivers. Canadian Journal of Zoology 73:663–671.
Environmental Protection Agency (EPA). 2000. Neuse River basin landuse/
landcover data. US EPA Landscape Characterization Branch, Research Triangle
Fuller, S.L.H. 1974. Clams and mussels (Mollusca: Bivalvia). Pp. 215–273, In C.W.
Hart and S.L.H. Fuller (Eds.). Pollution Ecology of Freshwater Invertebrates,
Academic Press, New York, NY.
Hanlon, S.D., and J.F. Levine. 2004. Notes on the life history and demographics of
the Savannah lilliput (Toxolasma pullus) (Bivalvia: Unionidae) in University
Lake, NC. Southeastern Naturalist 3(2):289–296.
660 Southeastern Naturalist Vol. 5, No. 4
Jenkinson, J.J. 1982. Cumberlandian mollusk conservation program. Pp. 95–103, In
A.C. Miller (Ed.). Report of Freshwater Mollusks Workshop. US Army Engineer
Waterways Experimental Station, Vicksburg, MS. 185 pp.
Johnson, P.D., and K.M. Brown. 2000. The importance of microhabitat factors and
habitat stability to the threatened Louisiana pearl shell, Margaritifera hembeli.
Canadian Journal of Zoology 78:271–277.
Johnson, R.I. 1970. The systematics and zoogeography of the Unionidae (Mollusca:
Bivalvia) of the southern Atlantic Slope Region. Bulletin of the Museum of
Comparative Zoology 140(6):263–449.
Menhinick, E.F. 1991. The Freshwater Fishes of North Carolina. North Carolina
Wildlife Resources Commission, Raleigh. 227 pp.
National Native Mussel Conservation Commission (NNMCC). 1998. National strategy
for the conservation of native freshwater mussels. Journal of Shellfish
Neves, R.J., and S.N. Moyer. 1988. Evaluation of techniques for age determinism of
freshwater mussels (Unionidae). American Malacological Bulletin 6:179–188.
Rogers S.O., B.T. Watson, and R.J. Neves. 2001. Life history and population
biology of the endangered tan riffleshell (Epioblasma florentina walkeri)
(Bivalvia: Unionidae). Journal of the North American Benthological Society
Strayer, D.L. 1999. Use of flow refuges by unionid mussels in rivers. Journal of the
North American Benthological Society 18(4):468–476.
Trimble, S.W. 1974. Man-induced soil erosion on the southern piedmont 1700–1970.
Soil Conservation Society of America, Ankeny, IA.
Watters, G.T., S.H. O’Dee, S. Chordas, and J. Rieger. 1999. Potential hosts for
Villosa constricta. Triannual Unionid Report 17:35.
Williams, J.D., M.L. Warren, Jr., K.S. Cummings, J.L. Harris, and R.J. Neves. 1993.
Conservation status of the freshwater mussels of the United States and Canada.
Zale, A.V., and R.J. Neves. 1982. Fish hosts of four species of lampsiline mussels
(Mollusca: Unionidae) in Big Moccasin Creek, Virginia. Canadian Journal of
Ziuganov, V., E. San Miguel, R.J. Neves, A. Longa, C. Fernandez, R. Amaro, V.
Beletsky, E. Popkovitch, S. Kaliuzhin, and T. Johnson. 2000. Life-span variation
of the freshwater pearl shell: A model species for testing longevity mechanisms
in animals. Ambio 29(2):102–105.