Notes on the Reproduction of the Streamside Salamander,
Ambystoma barbouri, from Rutherford County, Tennessee
Matthew L. Niemiller, Brad M. Glorioso, Christina Nicholas,
Julie Phillips, Jessica Rader, Elizabeth Reed, Kyle L. Sykes, Jason Todd,
George R. Wyckoff, Elizabeth L. Young, and Brian T. Miller
Southeastern Naturalist, Volume 8, Number 1 (2009): 37–44
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2009 SOUTHEASTERN NATURALIST 8(1):37–44
Notes on the Reproduction of the Streamside Salamander,
Ambystoma barbouri, from Rutherford County, Tennessee
Matthew L. Niemiller1, Brad M. Glorioso1, Christina Nicholas1,
Julie Phillips1, Jessica Rader1, Elizabeth Reed1, Kyle L. Sykes1, Jason Todd1,
George R. Wyckoff
1, Elizabeth L. Young1, and Brian T. Miller1,*
Abstract - Populations of Ambystoma barbouri (Streamside Salamander) have
recently been identified in the Central Basin of middle Tennessee. Little is known
regarding the distribution, natural history, and health of populations in Tennessee,
resulting in the salamander being “deemed in need of management” by state agencies.
Here we provide information regarding reproduction for the only known extant
populations in Rutherford County, TN. In February 2005, fifty-one egg masses from
three first-order streams were digitally photographed and analyzed to determine size
of egg mass, stage of development, ovum diameter, and embryo length. Number of
eggs per mass, size of ova, and size of embryos were comparable to that reported
in the literature. Egg masses varied noticeably in stage of embryonic development;
we estimate that oviposition in 2005 occurred between early December and early
February. Eurycea cirrigera (Southern Two-lined Salamanders) oviposited in the
same first-order streams and during the same time period as Streamside Salamander.
Continued deforestation and land development associated with urban sprawl from
the city of Murfreesboro threaten existing populations of Streamside Salamander.
The information in this study can be used to provide a basis for developing conservation
plans for the Streamside Salamander in middle Tennessee and for scheduling
construction activities such that they least affect breeding activities.
Ambystoma barbouri Kraus and Petranka (Streamside Salamander)
is a stream-breeding member of the Family Ambystomatidae (mole
salamanders) with a contiguous distribution in southeastern Indiana and
southwestern Ohio into central and northern Kentucky; isolated populations
are known from Livingston and Russell counties, KY, Wayne County, WV,
and Davidson, Jackson, and Rutherford counties in middle Tennessee (Kraus
and Petranka 1989, Niemiller et al. 2006, Petranka 1998, Regester and Miller
2000, Scott et al. 1997). Tennessee populations have only recently been
assigned to the Streamside Salamander (Scott et al. 1997) from reevaluation
of specimens collected during 1967 in Davidson County, 1973 in Jackson
County, and 1996 in Rutherford County that were originally identified as
A. texanum (Matthes) (Small-mouthed Salamander). The streams and surrounding
countryside used by Streamside Salamander in Davidson County
(Ashton 1966) have been greatly altered during the past 40 years with the
growth of metropolitan Nashville, and several attempts by B.T. Miller and
1Department of Biology, Middle Tennessee State University, Murfreesboro, TN
37132. *Corresponding author - email@example.com.
38 Southeastern Naturalist Vol. 8, No. 1
his students to locate breeding sites in this area during the past decade have
been unsuccessful. The status of the Jackson County population is currently
unknown, but breeding populations are extant in Rutherford County (Niemiller
et al. 2006, Regester and Miller 2000).
Most of the information on Streamside Salamander natural history is
derived from populations in Kentucky. Outside of the breeding period,
adults inhabit upland deciduous forests in the vicinity of ephemeral first- and
second-order streams with beds formed of exposed limestone slabs or bedrock
(Petranka 1998). Adults migrate to breeding streams from late October
through March (Petranka 1984), and females oviposit from mid-January to
early April (Barbour 1971, Keen 1975, Petranka 1984). Females typically
deposit eggs singly in a monolayer on the undersurface of submerged, fl at
rocks (Ashton 1966; Kraus and Petranka 1989; Niemiller et al., in press; Petranka
1982; Regester and Miller 2000). Autumn breeding migrations have
not been reported for the Tennessee populations, but breeding activities, as
determined by the presence of egg masses, begin during early December and
extend into March (Niemiller et al. 2006).
The distribution, natural history, and health of Streamside Salamander
populations within Tennessee remain largely unknown, with information on
these topics limited to that contained in the brief reports of Ashton (1966),
Scott et al. (1997), Regester and Miller (2000), and Niemiller et al. (2006).
Because of the limited distribution of the species and lack of information on
natural history, Streamside Salamander is “deemed in need of management”
by the Tennessee Wildlife Resources Agency (TWRA; Withers et al. 2004).
This state listing is analogous to the “special concern” category of other
states, and is used by the TWRA when the executive director believes that a
species (or subspecies) should be investigated so that a database can be created
on distribution, demography, habitat needs, limiting factors, and other
pertinent natural history information (Withers et al. 2004). The database is
then used to develop management measures to ensure the continued survival
of the populations. The purpose of our study was to provide information on
reproduction of the only known populations of the Streamside Salamander
Materials and Methods
On 16 February and 23 February 2005, we searched for egg masses of
Streamside Salamander ca. 100 m upstream and downstream from road
crossings of the three streams east of Christiana in Rutherford County: a firstorder
tributary to Long Creek (35º43'03"N, 86º22'29"W; datum NAD27; 16
Feb 2005), a first-order tributary to Middle Fork Stones River (35º40'52"N,
86º20'59"W; 16 Feb 2005), and a first-order tributary to Hurricane Creek
(35º43'59"N, 86º17'43"W; 23 Feb 2005). These localities are found within
the Inner Nashville Basin ecological subregion of the Interior Plateau in the
Stones River watershed (Griffith et al. 1997). This region is characterized
by gently rolling terrain with shallow soils and outcrops of Ordovician-age
2009 M.L. Niemiller et al. 39
limestone. These streams are of low gradient, fl ow over large expanses of
exposed bedrock, and are ephemeral, becoming reduced to isolated pools or
fl owing underground during late summer and fall.
Rocks within pool, run, and riffl e habitat were carefully lifted to locate
egg masses. Lifted rocks and other cover objects were returned to their
original positions to minimize habitat disturbance. Egg masses from the
three localities were photographed with a Sony Cybershot® DSC-F707
digital camera from a distance of 10–20 cm. Photographs were taken under
natural light conditions with a fl ash, and a ruler was positioned adjacent to
each mass to reference size. A digital image (1280 x 960 pixels) of each egg
mass was analyzed in Photoshop 6.0 (Adobe Systems, Inc., San Jose, CA)
to determine total number of eggs per mass (EPM), stage of development,
ovum size (mean diameter), and embryo length (mean total length). Stage
of development was determined according to Harrison (1969). Most eggs
forming a mass were at the same stage, although a few eggs varied as much
as two stages from the modal stage. We used the modal stage of each mass
for all calculations. Because of accumulation of silt and the growth of algae
on eggs, not all ova or embryos could be measured within an individual mass
(Fig. 1). Furthermore, internal ova of females collected from middle Tennessee
populations in 2002 and accessioned into the Middle Tennessee State
Herpetology Collection were counted to determine potential clutch size.
Fifty-one egg masses were photographed. EPM varied markedly at all
three localities, ranging overall from 1–211 (Table 1). Although the mean
EPM did not differ significantly between localities (F2,48 = 3.02, P = 0.058),
small sample size makes it difficult to interpret these results. Masses with
few eggs were at an advanced stage of development, and many were near
Figure 1. Comparative images of Ambystoma barbouri (Streamside Salamander) egg
masses observed on the undersurfaces of fl at submerged rocks. Ova and embryos
are easily observed and counted in recently laid masses or masses laid in sedimentfree
sections of streams (A), but visibility of developing ova and embryos may be
obscured by the accumulation of silt and algal growth in stream sections subject to
40 Southeastern Naturalist Vol. 8, No. 1
hatching when discovered. Consequently, mean EPM may be skewed towards
a smaller size. Among all three localities, stage of development of
egg masses ranged from Harrison stage 10 to stage 42, with the majority
of masses either at stages 10–14 (19.6%; n = 9) or stages 37–42 (68.6%;
n = 35). Mean stage of development could not be determined for two masses
because of accumulation of silt and algal growth. Mean diameter of stage
10–14 ova ranged from 2.3 mm to 4.2 mm and was significantly different
between sites (t = 7.93, df = 502, P < 0.0001; Table 1). All ova from Hurricane
Creek tributary were at stage 37 or greater. Mean total length of stage
37–42 embryos differed significantly between localities (F2,415 = 31.85, P <
0.0001). Females examined from museum specimens collected in 2002 contained
98–278 mature ova (n = 3).
As in other states, Tennessee populations of Streamside Salamander
breed in ephemeral first-order streams, depositing eggs singly in monolayers
on the undersurfaces of fl at, limestone rocks. Nearly all masses were
found within stream runs or pools; one egg mass with two eggs was found
attached to submerged grasses along the shoreline of a pool at the tributary to
Hurricane Creek. Streamside Salamanders breed syntopically with Eurycea
cirrigera (Green) (Southern Two-lined Salamander) in Rutherford County.
Three egg masses, two with attending females, of Southern Two-lined Salamander
were discovered on the undersurface of submerged rocks in riffl es
(two egg masses) and runs (one egg mass) within two meters of Streamside
Salamander egg masses in the tributary to the Middle Fork of the Stones
River. Larval Southern Two-lined Salamander were also present at this locality.
Both larvae and adult Southern Two-lined Salamander were observed
at another Streamside Salamander breeding locality; however, egg masses
of Southern Two-lined Salamander were not observed. The effects, if any,
of competition for oviposition sites, egg and larval development, and egg
Table 1. Reproductive data for 51 egg masses of Ambystoma barbouri (Streamside Salamander)
from three first-order streams in Rutherford County, TN. Locality = tributary of stream; # =
number of egg masses observed at locality; EPM = mean number of eggs per egg mass ± 1SD;
n = number of eggs measured; Diameter = mean diameter of ova in mm ± 1SD; TL = mean total
length of embryos ± 1SD. Stages according to Harrison (1969).
Ova (stages 10–14) Embryos (stages 37–42)
Locality # EPM Min–Max n1 Diameter Range n1 TL Min–Max
Long Creek 14 38.1 ± 43.8 2–170 67 2.7 ± 0.2 2.3–3.3 59 14.0 ± 1.7 11.8–18.5
Middle Fork 12 79.3 ± 58.6 16–191 437 3.1 ± 0.3 2.3–4.2 81 12.8 ± 0.9 10.8–14.3
Hurricane 25 35.7 ± 54.4 1–211 NA NA NA 278 14.2 ± 1.6 10.9–18.6
Total 51 46.6 ± 54.8 1–211 504 3.0 ± 0.3 2.3–4.2 418 13.9 ± 1.6 10.8–18.6
1Not all eggs or embryos in an individual egg mass could be measured because of algal or silt
2009 M.L. Niemiller et al. 41
and larval survivability between Streamside Salamander and Southern Twolined
Salamander are unknown, but warrant further study.
EPM in the present study is comparable to that reported in the literature.
Petranka (1984) reported from 8 to 1142 EPM, considerably greater than the
1 to 211 range observed in this study. Regester and Miller (2000) also reported
low EPM from nearby Puckett’s Creek in Rutherford County (range 5–65,
n = 10). The low EPM may suggest lower fecundity of Tennessee Streamside
Salamander populations, but it might be attributable to timing of oviposition.
Forty-five percent of the egg masses observed during this study contained
20 or fewer eggs. Of these 23 egg masses, 78.3% were beyond stage 37
(mean stage of development of eggs within a mass). The jelly coating of
the egg capsule deteriorates soon after hatching; consequently, egg masses
with few eggs may represent the last remaining eggs of larger clutches. Egg
masses with low numbers of eggs also may be refl ective of females that
were disturbed during oviposition, or those egg masses that were partially
ingested by predators. Few reports of the natural predators of eggs or adults
of Streamside Salamander exist, although Lepomis cyanellus Rafinesque
(Green Sunfish), crayfish, Nerodia sipedon Linnaeus (Northern Watersnake),
and the planarian Phagocata gracilis (Halderman) have been reported to
feed on larvae (Holomuzki 1989, Kats 1986, Petranka 1998, Petranka et al.
1987). Kats and Sih (1992) found that pools that contained predatory fish had
significantly lower densities of egg masses than nearby pools without fish.
Although Lepomis were not observed at the three stream localities, Cottus
carolinae (Gill) (Banded Sculpin) and Cambarus sp. (crayfish) were noted.
Additionally, N. sipedon pleuralis (Cope) (Midland Watersnakes) are locally
common and may be active on warm, rainy nights in late winter/early spring
(M.L. Niemiller, pers. observ.).
Petranka (1984) found an average of 262 (min-max = 184–397) mature
ova per adult female (n = 14) examined. These values exceeded those observed
in Rutherford County, TN (Regester and Miller 2000, present study).
However, our mean diameter of early stage ova lies within the min-max values
(2.4–3.8) reported by Petranka (1998). Consequently, it is unlikely that
differences in observed EPM between Kentucky and Tennessee populations
are the result of a tradeoff between ovum size and clutch size. Rather, female
Streamside Salamanders in Rutherford County, TN, likely distribute their
clutches among multiple, smaller egg masses under separate rocks. Other
species of Ambystoma (e.g., A. talpoideum (Holbrook) [Mole Salamander]
and Small-mouthed Salamander) have been reported to distribute eggs
in smaller masses or scatter their eggs singly (Semlitsch and Walls 1990,
Trauth et al. 1990) rather than deposit their entire clutch in a single mass.
Both diameter of ova and total length of late-term embryos differed
significantly between localities. Rather than being correlated to tradeoffs
between ovum size and clutch size, the observed difference may be an artifact
of small sample size. Although diameter of ova differed between two
of the localities surveyed (Long Creek and Middle Fork Stones River),
42 Southeastern Naturalist Vol. 8, No. 1
means and min-max values of both localities fall within the values reported
by Petranka (1998).
We conclude that female Streamside Salamander at our field sites oviposited
between early December 2004 and early February 2005. This estimate
is based on the observation of egg masses in differing stages of embryonic
development and assumes a 29–82 day incubation period (Petranka 1998).
Furthermore, hatchlings were observed on 23 February 2005 in a roadside
ditch hydrologically connected to the Hurricane Creek tributary. Timing of
oviposition during this study is consistent with the late December through
mid-February period reported by Regester and Miller (2000), and the late
December through early April period reported by Ashton (1966) for middle
Tennessee populations. By comparison, breeding occurs in central Kentucky
from late December to mid-April (Petranka 1998).
Streamside Salamander populations in middle Tennessee are threatened
by deforestation and development of land around breeding streams
(Niemiller et al. 2006). Road and other construction associated with the
expansion of the city of Murfreesboro are occurring near or adjacent to
known Streamside Salamander breeding sites (Niemiller et al. 2006, Regester
and Miller 2000). Such habitat disturbance is also the main threat
facing many populations of Streamside Salamander outside of Tennessee
(Petranka 1998, Watson and Pauley 2005). This urban sprawl will continue
to threaten Streamside Salamander populations in Rutherford County;
the human population of the county was predicted to increase nearly 75%
from 2000 to 2025 (Arnwine et al. 2003). Roads heavily dissect the area
inhabited by Streamside Salamander in Rutherford County (Niemiller
et al. 2006) and, during the breeding season, adult salamanders migrating
to breeding streams are killed unintentionally by motorists during
evening and nighttime rainstorms (B.T. Miller and M.L. Niemiller, pers.
observ.). Several forested riparian zones that support terrestrial activities
of Streamside Salamander are being converted to residential lawns (B.T.
Miller, pers. observ.). The continued loss of forested riparian habitat will
ultimately pose an insurmountable obstacle for the survival of Rutherford
County populations of Streamside Salamander. Loss of forested riparian
habitat increases insolation, water temperature, and exposure to ultraviolet
light (Corn et al. 2003), and also increases sedimentation and silt load,
which can negatively impact development of amphibian eggs (Corn and
Bury 1989, Corn et al. 2003). Nevertheless, the reproductive information
presented in this study should be used by both state and local agencies as
they develop conservation plans for these threatened populations. As development
escalates in southern Rutherford County, construction activities
should be curtailed from December through April to least affect breeding
and developing Streamside Salamander embryos. Limiting construction
to non-breeding periods will also reduce the amount of heavy traffic during
periods when transformed Streamside Salamander are surface active.
Moreover, forested land adjacent to first- and second-order stream breeding
2009 M.L. Niemiller et al. 43
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habitat and surrounding forests inhabited by adult Streamside Salamander.
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