Southeastern Naturalist 101 M.A. Anderson, et al. 22001144 SOUTHEASTERN NATURALIST 1V3o(1l.) :1130,1 N–1o0. 71 Population Survey of the Streamside Salamander in the Nashville Basin of Tennessee Michael A. Anderson1, Joshua R. Campbell1, Alison N. Carey1, Derec R. Dodge1, Ryan A. Johnston1, Emily R. Mattison1, Ryan J. Seddon1, Nathan L. Singer1, and Brian T. Miller1,* Abstract - Ambystoma barbouri (Streamside Salamander) inhabits upland deciduous forests associated with ephemeral first- and second-order streams throughout middle Tennessee. The distribution of Streamside Salamanders is centered in north-central Kentucky and extends into adjacent southeastern Indiana and southwestern Ohio. Disjunct populations are known from West Virginia, southern Kentucky, and middle Tennessee. Extant populations for middle Tennessee occur only within the southern Inner Nashville Basin (INB) ecological subregion of the Interior Plateau. Populations were found in Davidson and Jackson counties within the Outer Nashville Basin (ONB) during the 1960s and early 1970s, respectively; however, the status of these populations is unknown. To better determine the distribution of this species in the northern INB and the eastern ONB, we surveyed first- and second-order streams for eggs and larvae. We found Streamside Salamanders at only 2 of 78 localities. One of these breeding sites was adjacent to a previously known breeding stream in Wilson County, and the second site was in Trousdale County in the ONB, approximately 35 km north of the Wilson County sites and 49 km west of the historic Jackson County site. The distribution of Streamside Salamanders is still insufficiently k nown in middle Tennessee. Introduction Ambystoma barbouri Kraus and Petranka (Streamside Salamander) is a streambreeding member of the family Ambystomatidae (mole salamanders). Although previously recognized as a variant of A. texanum Matthes (Small-mouthed Salamander), Streamside Salamander was elevated to species status based on substantial differences between these species in morphology, behavior, and reproduction (Kraus and Petranka 1989). Streamside Salamander distribution is centered in north-central Kentucky and extends northward into adjacent southeastern Indiana and southwestern Ohio (Petranka 1998). Disjunct populations are known from West Virginia, southern Kentucky, and middle Tennessee (Kraus and Petranka 1989, Miller 2011, Petranka 1998). Adults inhabit upland deciduous forests associated with ephemeral first- and second-order streams in which breeding activities occur (Petranka 1982, 1984a). Breeding activities of Streamside Salamanders in Tennessee have been reported from early December to early April (Miller 2011; Niemiller et al. 2006, 2009). Eggs are typically deposited in a monolayer on the undersurface of submerged rocks in fishless pools and runs of streams associated with exposed limestone bedrock 1Department of Biology, Middle Tennessee State University, Murfreesboro, TN 37132. *Corresponding author - Brian.Miller@mtsu.edu. Manuscript Editor: Karen Powers Southeastern Naturalist M.A. Anderson, et al. 2014 Vol. 13, No. 1 102 (Holomuzki 1991, Kats and Sih 1992, Niemiller et al. 2006, Regester and Miller 2000). However, eggs have been found attached to submerged vegetation (Niemiller et al. 2009), as well as wholly or partially submerged foreign objects such as street signs (M.A. Anderson and B.T. Miller, pers. observ.). Oviposition in low-order streams associated with cedar glade habitats, including terrestrial breeding, has recently been reported (Mattison and Miller 2011, Niemiller et al. 2011). Although pond-breeding and stream-breeding Streamside Salamander populations have been reported (Petranka 1984b, Venesky and Parris 2009), only stream-breeding variants are known from Tennessee (Niemiller et al. 2009). Extant Tennessee populations occur in Bedford, Marshall, and Rutherford counties (Niemiller et al. 2006, 2011; Regester and Miller 2000). Historically, breeding populations were found in Davidson County (Ashton 1966, Scott et al. 1997), and juveniles have been reported from Jackson County (Scott et al. 1997). However, the status of these populations is unknown, with the former presumed extirpated as a result of urbanization of metropolitan Nashville (Niemiller et al. 2006). Furthermore, recently discovered populations have been associated only with the Inner Nashville Basin (INB); whereas, the aforementioned historic sites are located in the Outer Nashville Basin (ONB). Although the reported absence of Streamside Salamanders at two historic sites in Rutherford County (Niemiller et al. 2006)—a region that is experiencing tremendous human population growth (Mackun and Wilson 2011)—may indicate a potential decline in the middle Tennessee populations, the relatively recent discovery of eggs and larvae in a first-order stream in the Cedars of Lebanon State Forest (CLSF) in Wilson County (INB; Niemiller et al. 2011) indicates that our understanding of this species’ distribution in Tennessee is still poor. The Tennessee Wildlife Resources Agency currently classifies the Streamside Salamander as deemed in need of management, a rank analogous to the special concern category used in other conservation classification schemes (Withers 2009). The International Union for Conservation of Nature (IUCN) lists Streamside Salamander as near threatened because the species has a limited range, and declining habitat extent and quality (Hammerson 2004). Because Streamside Salamanders are associated with ephemeral streams in deciduous habitats, nearstream development and deforestation may have severe detrimental effects on the survivorship of this species throughout its range (Petranka 1998, Watson and Pauley 2005). To ascertain the status of historic populations and to determine the connectivity of ONB and INB populations, we surveyed for breeding activity in first- and second-order streams in the eastern section of the northern ONB and northern INB of middle Tennessee. Methods We searched for eggs, larvae, and adult Streamside Salamanders in 78 first- and second-order streams at road crossings in Davidson, DeKalb, Jackson, Smith, Sumner, Trousdale, and Wilson counties from January to April 2011 (Fig. 1). All streams surveyed were located within the northern INB and western and eastern ONB Southeastern Naturalist 103 M.A. Anderson, et al. 2014 Vol. 13, No. 1 ecological subregions of the Interior Plateau in the Cumberland, Caney Fork and Stones River watersheds (Griffith et al. 1997). We chose these sites based on similarity of habitat and proximity to historic and current breeding localities. Streams were low gradient and characterized by large expanses of exposed bedrock. Many of the streams surveyed were ephemeral, and all lacked predatory fish populations. We deemed streams with predatory fish (larvae, fry, or adults) as unlikely breeding localities and did not sample them. Our sampling methods closely followed Niemiller et al. (2006). Because we were not extrapolating density data, simple presence/absence data were sufficient. We sampled survey sites ≈100 m upstream and downstream from road crossings. Although streams may intersect roads at multiple points, we considered each road crossing as a distinct locality. We sought to maximize our search area and number of sites sampled, and therefore, visited each site only once. We lifted all rocks and other cover objects within streams to search for eggs and along stream banks to locate adults. We returned all cover objects to their original position to minimize habitat disturbance. We visually inspected pool and riffle habitat for larvae. Figure 1. First- and second-order streams surveyed for Ambystoma barbouri (Streamside Salamander) between January and April 2011. All search efforts were within the northern Outer Nashville Basin and northern Inner Nashville Basin, including portions of Davidson, DeKalb, Jackson, Smith, Sumner, Trousdale, and Wilson counties. Historic sites and currently known breeding sites are also noted. Sites indicated by a solid square are newly found breeding localities. Southeastern Naturalist M.A. Anderson, et al. 2014 Vol. 13, No. 1 104 Results We observed Streamside Salamanders at 2.6% (2 of 78) of streams sampled (Fig. 1). We found several clutches of eggs and many larvae in a first-orde r stream ≈3 km from the known Wilson County breeding locality in the CLSF, and we observed one clutch of eggs comprising three live and many dead embryos in various stages of development in a first-order stream in Trousdale County (TC). These findings documented new breeding localities for Streamside Salamander, and the TC site is the northern-most known extant breeding locality in Tennessee. Discussion Streamside Salamander populations in Tennessee are known only from the Inner Nashville Basin and Outer Nashville Basin ecoregions. The INB comprises most of Rutherford and Wilson counties, northern Bedford County, and extreme eastern Maury County. The Nashville Basin (Inner and Outer) is characterized by relatively flat terrain with many low- to moderate-gradient streams. At least 1322 named streams, and countless unnamed tributaries, occur within the INB and ONB (USGS 1981). We do not know how many of these streams are ephemeral, but of the 60 named streams in Rutherford County, only 15 are free-flowing throughout the year. If a similar proportion exist in other counties in the Nashville Basin, then there are likely >990 ephemeral streams in the Nashville Basin that provide potential breeding habitat for Streamside Salamanders. To date, breeding of this species has been documented in fewer than 25 (0.03%) streams in the Nashville Basin (Ashton 1966, Niemiller et al. 2006, Scott et al. 1997). However, Streamside Salamanders have not been found in more southern and western regions of the Nashville Basin (e.g., streams in Maury, Moore, Lincoln, and Giles counties). These four counties account for 433, nearly 33%, of named streams in the Nashville Basin. If we assume that breeding Streamside Salamanders are absent from these streams, and we eliminate them from the list of potential breeding localities, Streamside Salamanders have been found in 0.04% of presumed suitable streams in the Nashville Basin. Regardless of potential streams, Niemiller et al. (2006) found this species breeding in 12.5% of the streams they sampled in Rutherford, Bedford, and Marshall counties, and we found the species breeding in 2.6% of streams we sampled. Most known populations are clustered in the center of the Nashville Basin in southern Rutherford and northern Bedford counties, so our data represent survey efforts in distant localities, generally in locations nearing the northern and eastern boundaries of the Highland Rim, the upland area surrounding the Nashville Basin. Although our survey efforts were thorough, small populations might have gone undetected. Niemiller et al. (2006) reported an absence of individuals in sites where Streamside Salamander presence has since been confirmed (current study, Estabrooks 2010, Miller 2011). The lack of breeding populations observed at the sites we sampled may be a consequence of continuous habitat alteration and dissection by roadways. Whereas the new Wilson County locality represents a new breeding site, the Trousdale County Southeastern Naturalist 105 M.A. Anderson, et al. 2014 Vol. 13, No. 1 population represents a new county record for Streamside Salamander, as well as the only known breeding population in the Outer Nashville Basin. We did not find evidence of breeding near the historic sites in Jackson and Dav idson counties. Although we discovered eggs in a first-order stream in Trousdale County (TC), most of the embryos were dead in the only clutch found. The lack of viable embryos within the solitary clutch, as well as the lack of additional clutches in what appears to be suitable habitat is perplexing. Apart from a small riparian forest buffer, this breeding location is surrounded by land used for agriculture on the north and west sides. Similar habitat supports relatively large populations of Streamside Salamander (based on egg densities) in southern Rutherford and northern Bedford counties (Estabrooks 2010). However, all of TC is contained within the Old Hickory Lake watershed, in which 50% of the landscape is mixed or deciduous forest, with agricultural activities, such as row crops and pastures, accounting for less than 40% of land use (Goodhue et al. 2007). Data concerning stressor-pathogen effects on amphibians— pesticides, UV-B radiation, temperature, parasites, bacteria, viruses—are conflicting, and seem to be context-dependent (Forson and Storfer 2006, Mann et al. 2009). The apparent lack of additional fertilized egg masses at the TC site may be a temporal artifact, resulting from the date of our survey, which occurred late in the breeding season. Likewise, the lack of Streamside Salamander larvae does not necessarily indicate their absence; the stream was fast-flowing, which may have precluded larvae from persisting near the site of egg deposition. Although we found Streamside Salamanders in only 2 of 78 streams surveyed, our documentation of the TC breeding site extended the known breeding range in Tennessee by 35 km, and added a site adjacent to a recently discovered locality (Wilson County site; Niemiller et al. 2011). In addition, the TC site represents the only known Streamside Salamander population in the Outer Nashville Basin. Our results increase the number of documented current breeding localities from 16 to 18. 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