Visual Inspection Surveys of Southern Two-lined Salamander (Eurycea cirrigera) Population Numbers in Kankakee River State Park, Illinois

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Prepared by: Eric L. Peters, Ph.D., Professor of Ecology and Environmental Science

The geographical distributions of species are shaped by their tolerances to their environments. Populations at the edges of a species’ geographical range are often exposed to extremes of abiotic and biotic conditions that are not experienced by populations closer to the center of the range. Also, contiguous areas with appropriate conditions for a given species may become broken up over time due to factors such as climate change and human activities. The result may be a progressive fragmentation of the species’ range, resulting in small residual (relict) populations becoming progressively more isolated from each other. Such populations are often vulnerable to extinction, but if they persist long enough in isolation, they may evolve into distinct new species.

The southern two-lined salamander (Eurycea cirrigera, Fig. 1) belongs to a group of salamanders that are commonly known as brook salamanders. Eurycea is one of several genera within the family Plethodontidae (lungless salamanders), the largest family of salamanders (with more than 350 species, AmphibiaWeb 2010). There are 26 known species within the genus (AmphibiaWeb 2010), most of which live in eastern and central North America (several species are confined to the Edwards Plateau in central Texas). The majority of Eurycea species are endangered, restricted in range, or are known from only isolated caves, springs, or artesian wells.

Figure 1. The southern two-lined salamander, Eurycea cirrigera (Conant 1998). The scale is approximately life size.

Eurycea cirrigera closely resembles the northern two-lined salamander (E. bislineata) and is considered by some taxonomists to be a subspecies of E. bislineata (E. b. cirrigera), rather than a distinct species. Both salamanders are approximately 6.5 to 8.9 cm in total length, with a maximum length of about 11.5 cm (about 55-60% of this length is the tail, Conant 1998). Both species generally have a broad yellow stripe down the center of the back (which is occasionally orange-, brown, green, or bronze). This dorsal stripe is often sprinkled with small back spots (which occasionally join together and form a thin dorsal stripe), and is bordered by two broad black longitudinal stripes. E. cirrigera is distinct in having 14 lateral folds (costal grooves), on the body, compared with 15 or 16 in E. bislineata (Conant 1998). Males have a small tentacle” beneath their Two-lined salamanders inhabit small streams, brooks, and other wet areas throughout their range. They are absent from aquatic habitats where predatory fishes are present. E. cirrigera’s range extends from southern Virginia west to eastern Illinois, and south to northern Florida (Fig. 2). They are usually found under rocks, logs, piles of wet leaves, and other objects adjacent to and in small streams and springs. Once uncovered, they will quickly run or swim away. In warm, wet weather they may forage for food in adjacent woodlands at night. They feed mostly on small aquatic invertebrates (especially arthropods), and the larvae also prey upon freshwater crustaceans.

Initially, three subspecies of a single species of two-lined salamander was recognized (Kozak and Montanucci 2001), ranging across the U.S. east of the Mississippi River from Louisiana to southern Ontario (Fig. 2): Eurycea b. bislineata (the northern two-lined salamander, a northeastern form), E. b. wilderae (the Blue Ridge two-lined salamander, found in the Appalachian Mountains from southwest

Visual Inspection Surveys of Southern Two-lined Salamander (Eurycea cirrigera) Population Numbers in Kankakee River State Park, Illinois

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Eurycea bislineata

Eurycea cirrigeraEurycea wilderae

KRSPWC

AC

Figure 2. Distribution of E. cirrigera (southern two-lined salamander) as well as E. wilderae and E. bislineata in North America (redrawn from Conant 1998). The map shows the approximate locations of the Kankakee River State Park, Illinois (KRSP), Warren County, Indiana (WC), and Aiken County, South Carolina locations (AC) sampled by Boyle (1995).

Virginia to northern Georgia), and E. b. cirrigera (the southern two-lined salamander, a lowland form of the Atlantic and Gulf Coastal Plains (Conant 1998). The debate over whether the members of this “Eurycea bislineata complex” represent subspecies or full species was addressed by Petranka (1998), who did not recognize E. cirrigera as a separate species. Two subsequent studies (Kozak and Montanucci 2001, Camp et al. 2000) disagreed with this more conservative view, finding significant genetic differences between cirrigera and wilderae. Both groups are, in the absence of any geographical barrier, occupying contact zones (i.e., both “species” occupy the same niche), however there is little or no gene exchange, nor any evidence of hybridization (Kozak and Montanucci 2001, Camp et al. 2000). Based on these results and on morphological analyses (e.g., the differences in the number of costal grooves mentioned above), these authors agreed that E. cirrigera and E. wilderae, should be regarded as separate species.

E. cirrigera’s presence in northeastern Illinois was first documented from a single specimen collected in 1932 in Custer Park, Will County (Mierzwa 1989). Two additional specimens were collected in 1953 at Rock Creek within the Kankakee County area of Kankakee River State Park (KRSP). In 1988, a new population was found in the Will County area of the KRSP (Mierzwa 1989). Several other Illinois populations were discovered in 1995 (Mauger et al. 2000). Populations have since been found in tributaries on both the north and south bank of the Kankakee River within the KRSP.

Recently, evidence of the genetic distinctiveness of the isolated KRSP populations was obtained from microsatellite DNA samples of populations living in tributaries on both banks of the Kankakee River (Fig. 3). Microsatellite DNA samples from KRSP locations were also compared with the next nearest population (in Warren County, Indiana), and a distant population in Aiken County, South Carolina (Boyle 2005). Pair-wise comparisons indicated significant differences at all seven loci between the KRSP and Aiken County samples and significant differences in six out of seven loci between the KRSP and Indiana population samples. There was a significant correlation (r = 0.98) between the mean genetic and geographical distance over all population locations. Differentiation within the KRSP samples showed significant variability at three of the seven loci, with pair-wise comparisons of Fst (a correlation measurement of genetic difference between pairs of populations) indicating statistically-significant genetic differences were present in eight out of ten population matches. This included two of three site

Visual Inspection Surveys of Southern Two-lined Salamander (Eurycea cirrigera) Population Numbers in Kankakee River State Park, Illinois

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Figure 3. Map of sampling locations within the Kankakee River State Park (KRSP), Will County IL (the park is bordered on the north and south by Illinois State Routes 102 and 113, respectively). The Park is bisected by the Kankakee River. All locations (also see Mauger et al. 2000) lie along small, unmapped springs and seeps that are tributaries of the river.

comparisons on the north and south sides of the Kankakee River, suggesting that the river forms an isolating boundary between these locations.

Populations E. cirrigera inhabiting tributaries of the Kankakee River within the Will County portion of the KRSP have been monitored by students enrolled in biology classes at Chicago State University since 1996, primarily along the north bank of the Kankakee River (Fig. 3, we will be visiting the 102-2, 102-3, and 102-5 sites today). A previously-known site on Rayn’s Creek (102-1) was flooded by a beaver dam built in 2002-03 and this site has not been sampled since. In 2003, our class found a previously unreported population at what we designated as 102-5 (the Rock Creek picnic ground, where we will make our first stop).

The method used is known as a Visual Inspection Survey (VIS, also sometimes known as a Visual Encounter Survey). In these surveys, students in the class are divided into 4-5 groups and use tape measures to establish 4-5 linear transects at each habitat. One group of 3-4 students makes the environmental measurements. The students in each group then conduct a timed search along one of the transects, carefully shifting and immediately replacing cover items (rocks, fallen logs, and piles of leaves) that lie within and immediately adjacent to the stream channels. The students count the numbers of adults and larvae revealed (but do not attempt to capture the salamanders). The data are normalized to the number and length of the stream transects searched, the number of students searching, and the search time. These are tabulated as the number of individual adult or larval salamanders encountered per meter of stream searched per person searching per minute. In addition, environmental data that might influence the abundance of salamanders, including light levels, soil and water temperatures, and water quality parameters such as the pH, conductivity (in ppm: representing the number of anions and cations per mL of water), and (occasionally) dissolved oxygen (dO2, in mg of O2 per mL of water) concentrations of the stream waters may be recorded.

The purpose of this field exercise is to continue monitoring the population size and habitat preferences of this isolated population of E. cirrigera, which is located at the extreme northern and western part of the species’ range. The goal will be to note any apparent changes in the abundances of this species at the KRSP, and to identify what kinds of habitats appear to support the most individuals. This information may then be used in developing recommendations for proper management of the habitat for the conservation of these Illinois populations.

Literature Cited

AmphibiaWeb. amphibiaweb.org (accessed 16 September 2010).

Visual Inspection Surveys of Southern Two-lined Salamander (Eurycea cirrigera) Population Numbers in Kankakee River State Park, Illinois

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Boyle, M. Genetic distinctiveness of a peripheral Illinois population of the southern two-lined salamander (Eurycea cirrigera). 2005. Masters Thesis. Chicago State University

Camp, C., J. Marshall, K. Landau, R. Austin, and S. Tilley. 2000. Sympatric occurrence of two species of the two-lined salamander (Eurycea bislineata) complex. Copeia 2000: 572-578.

Conant, R. 1998. A Field Guide to Reptiles and Amphibians of Eastern and Central North America. 3nd Ed. Boston, Houghton Mifflin Company.

Kozak K., and R. Montanucci. 2001. Genetic variation across a contact zone between montane and lowland forms of the two-lined salamander (Eurycea bislineata) species complex: a test of species limits. Copeia 2001: 25-34.

Mierzwa, K.S. 1989. Distribution and habitat of the two-lined salamander, Eurycea cirrigera, in Illinois and Indiana. Bull. Chicago Herp. Soc. 24:61-69.

Mauger, D., T. Bell, and E.L. Peters. 2000, Distribution and habitat of the two-lined salamander, Eurycea cirrigera, in Will County, Illinois: implications for inventory and monitoring. Pages 168-174 In H. Kaiser, G.S. Casper, and N. Bernstein (Eds.), Proceedings of the Midwest Declining Amphibians Task Force: Joint Meeting of the Great Lakes & Central Division Working Groups of the Declining Amphibian Populations Task Force, Milwaukee Public Museum, Milwaukee, WI. 21-22 March 1998.

Petranka J. 1998. Salamanders of the United States and Canada. Smithsonian Institution Press, Washington, DC.