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` 1 INFLUENCE OF GEOMORPHOLOGY ON THE POPULATION STRUCTURE AND ECOLOGY OF THE HELLBENDER SALAMANDER ( CRYPTOBRANCHUS ALLEGANIENSIS) By KIRSTEN A. HECHT KARDASZ A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2011
` 2 2011 Kirsten A. Hecht Kardasz
` 3 To my son, Dmitry, and those who have dedicated their lives to conserving the natur al world for future generations
` 4 ACKNOWLEDGMENTS I am indebted to Dr. Max Nickerson and Dr. Perran Ross for their advice, ideas, and assistance with my research project and manuscript. I would also like to thank them in addition to The School of Natural Resources and Environment and the Ross Family Syndicate for financ ial assistance that prevented homelessness and starvation during my time as a student. Thank you to Phil Colclough and the Knoxville Zoo, Dr. Michael Freake, and Dr. Marcy Souza for providing data, technical support and input. Special thanks to Andrea D rayer for help and advice, members of the Williams Lab at Purdue University and all volunteers for their field assistance, and Melrose Flockhart for lending me a vehicle during my time in need. Financial support for this research was provided by the Great Smoky Mountains Conservation Association: Carlos C. Campbell Fellowship, The Reptile and Amphibian Conservation Corp, and the Cryptobranchid Interest Group: Jennifer Elwood Conservation Grant. For housing assistance during my field research I would like to thank The Great Smoky Mountains Institute at Tremont, the Lodge at Valley View, and Century 21 Great Smoky Mountains Realty. I would also like to acknowledge the Great Smoky Mountains National Park and Paul Super for allowing me to conduct my re search within the park and for their assistance. Last but certainly not least, I would like to thank my family, particularly my husband and mother, for their support. This work would not have been possible without them. Research was conducted under National Park Service scientific research permit GRSM 2008 SCI 0052 and University of Florida ARC Protocol #017 08WEC.
` 5 TABLE OF CONTENTS page ACKNOWLEDGMENTS ................................ ................................ ................................ .. 4 LIST OF TABLES ................................ ................................ ................................ ............ 7 LIST OF FIGURES ................................ ................................ ................................ .......... 8 LIST OF ABBREV IATIONS ................................ ................................ ........................... 10 ABSTRACT ................................ ................................ ................................ ................... 11 CHAPTER 1 INTRODUCTION ................................ ................................ ................................ .... 13 Factors Influencing Animal Populations ................................ ................................ .. 13 The Eastern Hellbender ................................ ................................ .......................... 17 General Description ................................ ................................ .......................... 18 Life His tory ................................ ................................ ................................ ....... 20 Population Studies ................................ ................................ ........................... 21 Geomorphology of the Smoky Mountains and Geology of Little River .................... 23 Objectives ................................ ................................ ................................ ............... 25 2 MATERIALS AND METHODS ................................ ................................ ................ 34 Study Site ................................ ................................ ................................ ............... 34 Field Sampling Methods ................................ ................................ ......................... 36 Data Analysis ................................ ................................ ................................ .......... 38 3 RESULTS ................................ ................................ ................................ ............... 44 General Results ................................ ................................ ................................ ...... 44 Population Structure ................................ ................................ ............................... 44 Microhab itat ................................ ................................ ................................ ............ 45 Body Condition ................................ ................................ ................................ ....... 46 Larval Diet ................................ ................................ ................................ ............... 47 4 DISCUSSION ................................ ................................ ................................ ......... 68 Population Struc ture ................................ ................................ ............................... 68 Microhabitat ................................ ................................ ................................ ............ 72 Body Condition ................................ ................................ ................................ ....... 78 Larval Diet ................................ ................................ ................................ ............... 80 5 CONCLUSIONS ................................ ................................ ................................ ..... 88 APPENDIX: WENTWORTH PARTICLE S IZE CATEGORIES ................................ ...... 91
` 6 LIST OF REFERENCES ................................ ................................ ............................... 92 BIOGRAPHICAL SKETCH ................................ ................................ .......................... 10 1
` 7 LIST OF TABLES Table page 3 1 Variable estimates and odds ratios from an ordinal logistic regression model based on streambed particle size classes at sites used by larval (n=25), sub adult (n=26), and adult (n=38 ) hellbenders ( Cryptobranchus alleganiensis ) captured in Little River, TN. ................................ ................................ ................ 49 3 2 Variable estimates and odds ratios from a binomi al logistic regression model based on streambed particle size classes at sites used by hellbenders ( Cryptobranchus alleganiensis ) (n=89) and random locations (n=50) within Little River, TN. ................................ ................................ ................................ ... 50 3 3 Variable estimates and odds ratios from a binomial logistic regression model based on streambed particle size classes (with particles <32 mm combined into one category) at sites used by hellbenders ( Cryptobranchus alleganiensis ) (n=89) and random locations (n=50) within Little River, TN. ........ 51 3 4 Variable estimates a nd model fit for linear regressions of hellbender ( Cryptobranchus alleganiensis ) body condition (mass (g) vs. transformed total length (mm)) in three rivers. ................................ ................................ ........ 52 3 5 Contents of diet samples taken from larval hellbenders ( Cryptobranchus alleganiensis ) in Little River, TN ................................ ................................ ......... 53
` 8 LIST OF FIGURES Figure page 1 1 Historic range of the eastern hellbender ( Cryptobranchus alleganiensis alleganiensis ) and the Ozark hellbender ( Cryptobranchus alleganiensis bishopi ) in the eastern United States ................................ ................................ .. 28 1 2 Adult hellbender ( Cryptobranchus alleganiensis ) in Little River, T N demonstrating morphological adaptations to the s tream environment including dorsally flattened body, cryptic coloration, lateral folds, and toe discs. ................................ ................................ ................................ .................. 29 1 3 Gilled larval hellbender ( Cryptobranchus alleganiensis ) measuring 69 mm in total length capt ured in Little River, TN. ................................ ............................. 30 1 4 Percentage of larval hellbenders in sampled populations of hellbenders in the North Fork of White River, MO (n=10); Nia ngua River, MO (n=3); Little River, TN (n=16), and other Missouri rivers (n=1) (Spring River, Eleven P oint River, Gasconade River, Big Piney River).. ................................ ................................ .. 31 1 5 Histogram of the size distribution of hellbenders captured in 2000 (n=33) during surveys of Little River, TN. ................................ ................................ ....... 32 1 6 Physiographic provinces of the Appalachians ................................ .................... 33 2 1 Human recreati onal use on Little River, TN in Great Smoky Mountains National Park. ................................ ................................ ................................ .... 42 2 2 Study site (Little River, TN; USA). ................................ ................................ ...... 43 3 1 Histogram of size distribution of captured hellbenders ( Cryptobranchus alleganiensis ) from 2000 2010 in Little River, TN (n=500). ................................ 54 3 2 Yearly size distribution histograms of captured hellbenders (Cryptobranchus alleganiensis ) from 2000 2010 in Little River, TN. ................................ .............. 55 3 3 Comparison of hellbender ( Cryptobranchus alleganiensis ) size class distributions sampled from Little River, TN in 2006 (n=113) and 2008 (n=117), with the North Fork of the White River, MO in 1969 (n=478) ................ 56 3 4 Scatter plot with linear regression line of water temperature ( C) vs. hellbender total length (mm) in Little River, TN (n=102). ................................ .... 57 3 5 Scatter plot with linear regression line of water depth (mm) vs. hellbender total length (mm) in Little River, TN (n=104). ................................ ...................... 58
` 9 3 6 Scatter plot with linear regression line of shelter size (mm ) vs. hellbender total length (mm) in Little River, TN (n=217). ................................ ...................... 59 3 7 Box plots comparing shelter size (mm) among three hellbender stage classes, larvae (n=61), sub adults (n=56), and adults (n=100), in Little River, TN ................................ ................................ ................................ ..................... 60 3 8 Bar graph showing me an standard error of the mean (SEM) for shelter size (mm) used by three stage classes of hellbenders, larvae (n=61), sub adults (n=56), and adults (n=100), in Little River, TN.. ................................ .................. 61 3 9 Results of Wolman pebble count survey in the Little River, TN showing streambed particle size distribution in Little River, TN (D50=small cobble). ....... 62 3 10 Bar graph comparing streambed particle size categories found below shelter rocks among hellbender stage classes, larvae (n=25), sub adults (n=26), and adults (n=38) in Little River, TN. ................................ ................................ ......... 63 3 11 Bar graph comparing streambed particle size categories found at sites used by hellbenders (n=89) and random loc ations (n=50) in Little River, TN. ............. 64 3 12 Examples of abnormalities of Cryptobranchus alleganiensis captured in Little River, TN. ................................ ................................ ................................ .......... 65 3 13 Scatter plot with regression lines comparing body condition of hellbenders ( Cryptobranchus alleganiensis ) from three rivers (Little River, TN (n=527); Hiwassee River, TN (n=507); North Fork of the White River; MO (n=463) with differing crayfish relative frequencies. ................................ ................................ 66 3 14 Pie chart of total food items identified from larval hellbender ( Cryptobranchus alleganiensis ) diet samples (n=23) taken from Little River, TN. .......................... 67 4 1 Grouped histogram showing differences in size class distributions of hellbenders ( Cryptobranchus alleganiensis ) captured in Little River, TN from 2000 2010 (n=500) and the North Fork of the White River, MO in 1969 (n=478). ................................ ................................ ................................ .............. 85 4 2 Map of the eastern United States showing protected areas in the southern Appalachian and O zark regions ................................ ................................ .......... 86 4 3 Annual peak streamflow at Little River, TN USGS station within Great Smoky Mountains National Park ................................ ................................ .................... 87
` 10 LIST OF ABBREVIATION S ANCOVA Analysis of covariance ANOVA Analysis of variance CITES Convention on International Trade in Endangered Species of Wild Fl ora and Fauna FISP Federal Interagency Sedimentation Project GSM Great Smoky Mountains GSMNP Great Smoky Mountains National Park HR Hiwassee River, Tennessee IUCN International Union for Conservation of Nature LR Little River, Tennessee MPLR Middle Prong of Little River, Tennessee NFWR North Fork of the White River Missouri PIT Passive Integrated Transponder SVL Snout vent length TDS Total dissolved solids TL Total length USGS United State s Geological Survey VIE Visible Implant Elastomer
` 11 Abstract of Thesis Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Science INFLUENCE OF GEOMORPHOLOGY ON THE POPULATION STRUCTURE AND ECOLOGY OF THE HELLB ENDER SALAMANDER ( CRYPTOBRANCHUS ALLEGANIENSIS ) By Kirsten A. Hecht Kardasz December 2011 Chair: Max A. Nickerson Cochair: James Perran Ross Major: Interdisciplinary Ecology The hellbender ( Cryptobranchus alleganiensis ) is an imperiled salamander that has experienced declines in many parts of its range. L ittle knowledge of the general ecology of the larval stage exists because studies including all stage classes, particularly larvae, are rare In 2000, a brief study in Grea t Smoky Mountains National Park discovered a population of C. alleganiensis where larvae were regularly encountered and few adults were captured. The authors of the 2000 study hypothesized that the size structure of hellbenders in Little Riv er, Tennessee was potentially influenced by differences in larval hellbender habitat and crayfish abundance from other studied localities due to the geologic structure of the streambed. To further investigate this hypothesis, this study examined three mai n components: trends in hellbender population structure, microhabitat use of hellbender stage classes within Little River, and body condition of hellbenders in rivers with different crayfish abundances. Diurnal skin diving surveys were conducted in the su mmer and early fall months of 2008 2010 to locate hellbenders and collect habitat, morphometric, and diet data. Surveys conducted since 2000 in Little River suggest that the hellbender
` 12 population appears stable, with abundant larvae and regular recruitmen t. The number of larvae in Little River appears to be much higher than in most studied hellbender populations. Flooding induced mortality of larvae may affect long term population structure in Little River due to the influence of stream geomorphology on larval habitat use. Of the habitat variables measured during this survey, only shelter size appears to differ among stage classes, with larvae utilizing smaller shelters on average than adults and sub adults. Very coarse gravel was positively associated with hellbender occupancy in Little River. Abundance of crayfish, based on crayfish relative frequencies, correlated to overall body condition of hellbenders in the three rivers examined. Stomach samples collected from larvae suggest that hellbenders exp erience an ontogenetic shift in diet, with young individuals primarily consuming aquatic insect larvae. These results help fill in knowledge gaps regarding the larval stage of the hellbender, as well as highlight the potential impacts of stream geomorphol ogy on the ecology of a hellbender population.
` 13 CHAPTER 1 INTRODUCTION Factors Influencing Animal Populations Mechanisms influencing dynamics and regulation of animal populations have been a major research focus and a source of debate thro ughout the history of ecology (Murdoch, 1994). Although understanding these mechanisms can shed light on a number of ecological questions including the dynamics of communities, biotic interactions, evolutionary history, and conservation status of populati ons, determining which factors ultimately affect populations is complex as several factors, both biotic and abiotic, can work concurrently (Murdoch, 1994; Rodenhouse et al., 1997). Furthermore individual populations and even subsets within a particular po pulation can experience different responses to similar mechanisms (Dobson and Oli, 2001). Despite these inherent difficulties, identifying mechanisms is important because of their influence on the basic demographics of populations including birth and deat h rates, immigration, emigration, growth rates, and fecundity. Factors influencing populations are often classified into density dependent and density independent categories. The impacts of biotic factors such as disease and biotic interactions, including predation and competition, are typically linked to population densities and are therefore considered density dependent. In contrast, many abiotic factors are categorized as density independent. Climatic extremes and natural disasters such as flooding are examples of factors that work independently of population den sity. The physical habitat where a population lives may also serve as an important abiotic influence on population dynamics. Habitat characteristics such as
` 14 shelter type and availability, chemistry, soils, and geology all potentially affect the demograph ics of populations. In aquatic systems the role of the physical environment is particularly important. Obligate aquatic species cannot typically relocate to new environments due to physiologic limitations. Physical tolerances also limit the range of spec ies within the aquatic system itself. Stream environments are unique and harsh environments to inhabitant due to constant environmental fluctuations and large spatial and temporal variation (Giller and Malmqvist, 1998 ; Peterson et al., 1983 ). The environment, therefore, is a critical factor in determining the density, structure, and distribution of populations within streams. The range of stream organisms is essentially a marriage of the physiochemical environments present in the stream wi th the physical tolerances of the animals (Giller and Malmqvist, 1998). Habitat variables that influence inhabitants vary depending on scale. At smaller scales stream flow patterns, temperature, and substrate are key components which influence how and wh ere organisms live in the stream environment (Giller and Malmqvist, 1998). The geologic setting, riparian vegetation, and land use surrounding streams become more important factors at larger scales (Giller and Malmqvist, 1998). Geomorphology, defined as shape them, directly and indirectly shapes many stream attributes. The geologic history of a stream determines its bedrock structure, which in turn affects stream characteristics and processes. Geomor phology can influence benthic substrate, flow patterns, pH, water chemistry, and nutrient levels within a stream, thereby influencing stream biota and communities on both local and regional scales (Swanson, 1980). Differences in
` 15 production and density of stream macro fauna have been linked to variations in geomorphology at both local levels and between different geologic provinces (Huryn and Wallace, 1987; Hwa Seong and Ward, 2007; Raymond Bouchard, unpubl. data). Eco regions based on geological provinces have also been noted to contain different assemblage groups (Rashleigh, 2004). Research examining influences on population dynamics has historically focused on overall population density or abundance, which can give an incomplete picture of population sta tus. The structure of a population can reveal a great deal more about the status of a population than population size estimates alone and is particularly valuable in conservation where understanding the threat of extinction for a population is important ( Alexander 1958; Downing 1980; Gillespie 2010) In species of conservation concern, age or stage composition can indicate overall population stability and lead to more accurate predictions regarding future p opulation trends (Crowder et al., 1994). A po pulation composed primarily of older individuals may be at risk of decline or extirpation due to low recruitment (Alexander 1958; Downing 1980). A population with few older individuals, but many young individuals could indicate population growth, high a dult mortality, or a failure to recruit young life stage classes into adults (Alexander 1958; Downing 1980) Understanding the structure of a population is also important because different age or stage classes can react differently to their environment and dissimilarly affect overall population dynamics (Dobson and Oli, 2001). In aquatic environments organisms often adapt life strategies that can cause differences in demographic rates among age or stage classes. Many stream species,
` 16 including fish, aqua tic insects, and amphibians develop complex life cycles or ontogenetic shifts in habitat use and diet, which are believed to be adaptations for increasing survival in a stressful environment (Werner and Gilliam, 1984; Foster et al., 1988; Giller and Malmqv ist, 1998). These shifts can serve as a type of refugia, limiting intra specific competition and predation (Werner and Gilliam, 1984; Colley et al., 1989; McGrath et al., 2007). While these adaptations may help reduce individual mortality, they can also make studying populations more complicated. Studies examining amphibian population structures are particularly needed. While amphibian populations are currently declining worldwide (Alford and Richards, 1999; V i et al., 2009), population dynamics and dem ographics of many amphibians remain unstudied (Duellman and Trueb, 1986; Alford and Richards, 1999; Swanack et al., 2009; Gillespie, 2010; Lips, 2011). As obtaining amphibian population and life history data that accurately considers all stage classes is difficult due to complex life cycles and ontogen e tic shifts data is often lacking for specific size or stage classes (Swanack et al., 2009; Gillespie 2010). L arval and juvenile classes can be difficult to study because they are generally cryptic, small, and sometimes use different habitat than other stages (Gillespie, 2010) Therefore, understanding the class st ructured dynamics of amphibian populations remains problematic The resulting information gaps have hindered researchers from fully comprehendi ng the scope of amphibian declines and prevented the identification of mechanisms affecting individual populations (Alford and Richards, 1999; Gillespie, 2010; Lips, 2011). Once population declines occur, information is even more difficult to obtain as in dividuals become rare (Gillespie 2010).
` 17 One amphibian species with few studies regarding its basic demographics and population dynamics is the hellbender salamander, Cryptobranchus alleganiensis (Daudin 1803) Currently listed as near threatened on the I nternational Union for Conservation of Nature (IUCN) red list (Hammerson and Phillips, 2004), hellbender populations appear to be declining in many parts of the range (Trauth et al., 1992; Wheeler et al., 2003; Briggler et al., 2007; Foster et al., 2009; N ickerson et al., 2009; Burgmeier, 2011b). The exact cause or causes of the declines remain difficult to pinpoint, but stream siltation, disease, collection, species introductions, and habitat loss are just a few of the cited problems facing this species ( Trauth et al., 1992; Hiler et al., 2005; Briggler et al., 200 7; Nickerson and Briggler, 2007; Nickerson et al., 2009). Due to these declines the hellbender is protected at the state level throughout most of its range, and was recently listed in Appendix I II of CITES (Convention on International Trade in Endangered Species of Wild Flora and Fauna) and the Federal endangered species list ( Anonymous 2011) The Eastern Hellbender Cryptobranchus alleganiensis is a member of the ancient giant salamander family Cryptobranchidae, which was present over 160 million years ago in China based on the fossil record (Gao and Shubin, 2003). Evidence of Cryptobranchidae in North America begins in the Upper Paleocene (Naylor, 1981). Today, the lone extant North American s pecies of these long lived, large, aquatic salama nders resides primarily in cool, oxygen rich streams in the mountainous regions of the eastern United States. There are currently two accepted subspecies: C. a. alleganiensis the eastern hellbender, which is found in the majority of the range, and C. a. bishopi the Ozark hellbender which is found in a small area of Misso uri and Arkansas (Figure 1 1).
` 18 General Description Hellbenders are one of the largest salamander species in North America. The largest he llbender ever recorded was captured in the Little Pigeon River just outside Great Smoky Mountains National Park (GSMNP) in Gatlinburg, TN. This female measured 740 mm in total l ength (TL) (Fitch, 1947). The largest known male at 686 mm TL was captured ne ar the same locality in 1936 (King, 1939). Despite females generally reaching overall longer lengths than males (Bishop, 1941; Humphries and Pauley, 2005), the length specific mass of the sexes can vary depending on locality and time of year (Bishop, 1941 ; Taber et al., 1975; Peterson et al., 1983; Peterson et al., 1998). Studies also suggest that the sexes differ in age at sexual maturity with females generally being older and thus larger before reaching adulthood (Dundee and Dundee, 1965; Taber et al., 1975 ; Peterson et al., 1983 ). Due to the lack of distinct morphological differences, the sexes are extremely difficult to differentiate in the field throughout most of the year (Bishop, 1941; Hillis and Bellis, 1971; Taber et al., 1975). During the breed ing season in late summer and early fall, however, males develop swollen cloacae making them easy to discern from females (Bishop, 1941; Nickerson and Mays, 1973). Cryptobranchus alleganiensis has adapted to life in stream riffles by developing many life s trategies common to animals in stream environments (Figure 1 2). Cryptic coloration helps them blend in with the streambed substrate where they reside (Nickerson and Mays, 1973). Coloration includes dark brown, grey, olive green, orange, and yellow with darker mottling commonly present (Nickerson and Mays, 1973; Petran ka, 1998). A large keeled tail and rough toe pads assists the hellbender in navigating stream bottoms (Nickerson and Mays, 1973). Their heads and bodies are
` 19 dorso laterally flattened allow ing them to squeeze into small spaces beneath rocks and minimize resistance from stream flow (Nickerson and Mays, 1973). The hellbender produces skin secretions, which may help them slide beneath rocks as well as serve other adaptive purposes (Nickerson an d Mays, 1973). These secretions are believed to be somewhat toxic and distasteful, serving as a potential defensive mechanism against predation (Brodie, 1971; Nickerson and Mays, 1973). them slippery and difficult to handle, which may represent an additional deterrent against predators. M ucous skin secretions may also aid in respiration (Nickerson and Mays, 1973). The genus Cryptobranchus reference to the lack of external gills in adults. Although external gills are lost as larvae transition into sub adults (Bishop, 1941), hellbenders retain gill slits throughout life, and are thus considered paedomorphic (Nickerson a nd Mays, 1973; Petranka, 1998; Nickerson, 2003). Mature C. alleganiensis primarily respire cutaneously with lateral folds on the body trunk assisting in this process (Guimond, 1970; Nickerson and Mays, 1973). Adults also possess lungs, but these appear to serve mostly as instruments for buoyancy, as they are essentially non functioning for respiration (Hughes, 1967; Guimond, 1970). Despite small lidless eyes, which are flattened like many aquatic amphibians, hellbenders appear to rely on visual cues in a ddition to chemical and tactile stimulus for feeding (Nickerson and Mays, 1973). They predominantly consume whole live food items by asymmetrical suction feeding where suction is created when one side of the
` 20 mandible rapidly descends (Nickerson, 2003). C ryptobranchus alleganiensis is largely nocturnal and forages at night and occasionally during overcast daylight hours (Nickerson and Mays, 1973). Throughout their range, crayfish comprise the majority of the adult hellbender diet, but they are known to co nsume a number of additional prey items including fish, snails, worms, aquatic insects, amphibians, aquatic reptiles, carrion, and even lampreys in some localities (Smith, 1907; Netting, 1929; Green, 1935; Bishop, 1941; Nickerson and Mays, 1973; Nickerson et al., 1983, Peterson et al.,1989). Cryptobranchus alleganiensis is also cannibalistic and will eat eggs and smaller conspecifics (King, 1939; Nickerson and Mays, 1973; Humphries et al., 2005). Non food items including rocks and leaves have been found in stomach samples and are believed to be incidental due to the feeding strategy of C. alleganiensis (Netting, 1929; Nickerson and Mays, 1973; Peterson, 1989 ). Life History C ryptobranchus alleganiensis passes through four distinct life stages: egg, larva, sub adult, and adult. Reproductive timing varies throughout the species range, but generally occurs in the late summer and early fall months (Smith, 1907; Smith, 1912; Green, 1933; King, 1939; Bishop, 1941; Dundee and Dundee, 1965; Nickerson and M ays, 1973). Hellbenders congregate at large boulder nest rocks and sometimes exhibit communal breeding (Smith, 1907; Peterson, 1988). After courtship, females lay large strings containing approximately 270 to 450 eggs, which are fertilized externally by males and often cannibalized by both sexes (Smith, 1907; Bishop, 1941; Nickerson and Mays, 1973; Peterson, 1988). Following fertilization one male guards the nest from inc ubate approximately 1 2 months before hatching ( Bishop, 1941; Peterson, 1988).
` 21 Hatchlings emerge at approximately 20 30 mm TL with a yellow yolk sac visible in their abdomen s external gills, and undeveloped limbs (Smith,1907; Bishop 1941). They are drab in color and lack the lateral skin folds noted on adults. Larvae quickly adapt the typical coloration of C. alleganiensis and absorb their yolk sac (Figure 1 3). After 1 2 years individuals attain 130 mm TL (Bishop, 1941) and reabsorb their external gill s, becoming sub adults. Sub adults closely resemble adult C. alleganiensis but have not yet reached maturity. Although location and sex appear to influence the timing of adulthood hellbenders generally reach sexual maturity between 5 8 years of age (Dund ee and Dundee, 1965; Taber et al., 1975; Peterson et al., 1988). Life expectancy is unknown in the wild, but one individual lived 29 years in captivity (Nigrelli, 1954). While a basic understanding of the life cycle of the hellbender is known, much less i s known about the sub adult stage of this species, and virtually nothing is known about larvae in the wild. Only two larval diet samples have been published (Smith, 1907; Pitt and Nickerson, 2006) and very few studies have focused on the ecology, habitat and behavior of larvae mostly due to the rarity of encountering larvae in most localities. In contrast, knowledge of the ecology and natural history of the adult hellbender, despite some gaps, is relatively abundant. It is therefore not surprising that s tudies regarding the population ecology of the species have been biased towards larger individuals. Population Studies Despite the conservation interest in C. alleganiensis data is sparse regarding the population dynamics of this species. Many localities lack historic data regarding population size and status, and many demographics of this species remain poorly understood. Population studies have primarily focused on snapshot estimates of
` 22 population size or adult population structure. Few studies have e xamined growth rates, fecundity, and survivability, and these studies have only been completed in a few localities in the Ozark region, which may not be representative for hellbenders across their range, particularly for the eastern subspecies (Topping and Ingersol 1971; Taber et al. 1975; Peterson et al. 1988). Limited historical data from a few previously studied drainages in New York and Missouri have given better insight into long term population trends (Wheeler et al. 2003; Foster et al. 2009). Recent research in these areas indicated that some populations are declining as well as shifting in overall structure. Comparisons of historical and recent data in Missouri populations suggested that in declining hellbender populations, size class distrib utions were shifting towards larger individuals, possibly indicating inadequate recruitment (Wheeler et al. 2003) Foster et al. (2009) noted not only overall decline Alleghany River drainage, but also shifts in sex ratio towards a male biased population In both of these studies, young individuals <20 cm (i.e. larvae and small sub adults) were missing from samples. It remains uncertain whether these size classes were absent from the population or ina dequately sampled perhaps due to their association with interstitial spaces in gravel beds (Nickerson and Krysko 2003). Regardless, little is known about larval hellbenders and few studies include data on larvae. However, in 2000 Nickerson et al. (2002 ) discovered a unique hellbender population while conducting research in a Tennessee stream During efforts by the U.S. Geological Survey (USGS) to catalog the amphibians C.
` 23 alle ganiensis as well as Necturus maculosus the common mudpuppy A short survey of the hellben der population in Little River (LR), Tennessee yielded 33 individuals, of which 48% (n= 16) were larval sized (<130 mm) (Nickerson et al. 2002). This percentage wa s in stark contrast to those recorded for other hellbender populations (e.g. Peterson et al. 1988; Wheeler et al. 2003; Foster et al. 2009) (Figure 1 4) Furthermore, the proportion of adult hellbenders to larvae within LR (Figure 1 5) was the lowest o f any studied river system (Nickerson et al. 2003 ). Additional research has confirmed that larvae are regularly captured in this stream from year to year, and that although adult hellbenders are more abundant than originally thought, very large adults ar e still rare (Freake, unpubl. data). Geomorphology of the Smoky Mountains and Geology of Little River The Great Smoky Mountains (GSM) are part of the Southern Appalachian Region, which lies within the Appalachian Highlands of the eastern United States. Th is area is comprised primarily of four physiographic provinces: Appalachian Plateau, Valley and Ridge, Blue Ridge, and Piedmont (Figure 1 6). Fenneman (1917) formed these classifications based primarily on differences in geomorphology and geologic histor y. Rocks in Southern Appalachia vary throughout the region and include limestone, dolomite, shale, sandstone, siltstone, gneiss, schist, phyllite, as well as a variety of metamorphosed rock. The Appalachian region displays this diversity in rock type and structure due to the unique geologic history of each province. The GSM are located within the Blue Ridge Province. The Blue Ridge Province is a high mountainous area of the Southern Appalachians and also includes the Unaka and Blue Ridge Mountains. Met amorphic rock comprises most of the region. Rocks underlying the Southern Appalachians,
` 24 including the Blue Ridge Province formed over one billion years ago, when the supercontinent Rodinia formed. As the continental crust expanded 750 million years ago, Rodinia began to pull apart, forming a deep basin. The Ocoee Basin, which was located in present day east Tennessee, west ern North and South Carolina, and northern Georgia, filled with saltwater. Vast amounts of river transported sediments, including sand, silt, clay, and gravel, settled within the basin, creating what would become the bedrock of the GSM. After millions of years of sedimentation within the basin, continents began to move together again. Around 270 million years ago, the continents that became modern day North America and Africa collided, essentially pushing the formed rocks upward and forming the Appalachi an Mountains. In the Blue Ridge Province, the pressure and heat from the continental collision metamorphosed much of the sedimentary rock. Following millions of years of weathering and erosion, the landsc ape we see today developed. LR lies entirely withi n the southern portion of the Blue Ridge physiographic province. The bedrock of LR is comprised primarily of late Precambrian Elkmont and Thunderhead metamorphosed sandstone (Mast and Turk, 1999). Over time, the flowing water has eroded away some exposed bedrock leaving large densities of dense rounded boulders, cobble, and gravel in the streambed. Hellbenders are generally associated with large flat rocks, which they utilize for shelter and nest rocks (Bishop 1941, Hillis and Bellis, 1971). Many of th e well studied hellbender streams contain bedrock comprised largely of limestone and other sedimentary rocks. These types of rocks are more susceptible to weathering and erosion than metamorphic rock and typically fragment and erode into flat slabs rather than the rounded rocks characteristic
` 25 of LR. Interstitial habitat is limited within the LR streambed as sand often fills in many po rtions of the gravel beds. The lack of interstitial space in the gravel substrate as well as the availability of rounded s helters makes LR different from most other studied hellbender localities in its streambed morphology. Objectives LR makes larvae more susceptible to capture, and coupled w ith reduced crayfish populations, translates to fewer adult C. alleganiensis other locations ar e often located within the interstitial spaces of gravel (Smith, 1912; Nickerson and Mays, 1973; Nickerson et al., 2003). These sp aces are unavailable within LR due to the characteristics of the streambed. Furthermore, crayfish, the principle component of the adult hellbender diet, appear to be scarcer and smaller in size in LR than in other well studied hellbender localities (Nicke rson et al, 2003). This trend may be influenced by the bedrock structure of LR as previous researchers have noted smaller densities of crayfish in streams with non carbonated bedrock in comparison to sites comprised of carbonate rocks ( Raymond Bouchard, p ers. comm.). Trends of higher production rates in hard water streams have also been noted in a number of other macro invertebrate species and may be caused by the influence of water chemistry on algae and microbes, which ultimately impacts other biota thr ough trophic interactions (Hwa Seong and Ward, 2007). Based on the hypothesis of Nickerson et al. (2003) which links the population structure of hellbenders to geologic characteristics as well as crayfish frequencies, this study was conducted to further ex amine the role of the geomorphology on the general ecology and population dynamics of C. alleganiensis within LR. This study examined
` 26 hellbenders. The first objective of this study was to examine the population structure in more detail, and investigate the population structure of hellbenders over mult iple years. The findings of Nickerson et al. (2002 ) were limited by small sample size and reduced search hours Additional study was needed to confirm the differences in hellbender population structure from well studied streams. The second objective was to quantify microhabitat use of C. alleganiensis particularly among the larval stage, within LR during the summer and early fall months. Microhabitat available to stream dwelling animals is often reliant upon the general geomorphology of the stream. In the case of LR, the geologic structure of the streambed has mostly eliminated the type of habitat typical of larvae found in other streams. Although the lack of interstitial spaces within the gravel has been suspected of limiting the recruitment of young individuals within LR, no specific study of larval habitat has been undertaken. While Nickerson et al. (2003) suggested that larval habitat differed in LR when compared to other localities, the actual habitat being utilized in LR has been only anecdotall y noted. I hypothesized that despite the lack of interstitial spaces, there would still be some type of ontogenetic shift in microhabitat use among stage classes. These shifts serve as a form of refugia, reducing rates of intraspecific competition and pr edation among stage classes, and are common among aquatic organisms (Werner and Gilliam, 1984; Giller and Malmqvist, 1988) The low abundance of crayfish was also cited as a potential cause for the lack of large adult C. alleganiensis within LR (Nickerson et al., 2003). If prey densities do indeed impact the survival of adult hellbender, I would expect them impact the body
` 27 condition of hellbenders. To investigate the impact of low prey densities on the body condition of hellbenders, body condition was com pared in rivers with differing crayfish frequencies. I hypothesized that hellbenders from a river with a low crayfish relative frequency would exhibit poorer body condition than individuals from rivers exhibiting higher crayfish abundance. As the natural diet of larval hellbenders is relatively unknown, the diet of larvae was also investigated to determine if low crayfish densities might also affect the youngest stage class.
` 28 Figure 1 1. Historic range of the eastern hellbender ( Cryptobranchus alleganie nsis alleganiensis ) and the Ozark hellbender ( Cryptobranchus alleganiensis bishopi ) in the eastern United States (Modified from U.S. Geological Survey National Amphibian Atlas, 2010)
` 29 Figure 1 2. Adult hellbender ( Cryptobranchus alleganiensis ) in Little River, TN demonstrating morphological adaptations to the stream environment including dorsally flattened body, cryptic coloration, lateral folds, and toe discs. Photo courtesy of Kirsten Hecht Kardasz.
` 30 Figure 1 3. Gilled larval hellbender ( Cryptobranchus alleganiensis ) measuring 69 mm in total length captured in Little River, T N Photo courtesy of Kirsten Hecht Kardasz.
` 31 n=765 n=1132 n=1209 n=33 Figure 1 4. Percentage of larval hellbenders in sampled populations of hellbenders in North Fork of White River MO (n=10); Niangu a River, MO (n=3); Little River, TN (n=16), and other Missouri rivers (n=1) (Spring River, Eleven Point River, Gasconade Rive r, Big Piney River). (Modified from Nickerson et al., 2003).
` 32 Figure 1 5. Histogram of the size distribution of hellbenders captured in 2000 (n=33) during surveys of Little River, TN. (Modified from Nickerson et al., 2003)
` 33 Figure 1 6. Physiographic provinces of the Appalachians (Modified from Fenneman and Johnson, 1946)
` 34 CHAPTER 2 MATERIALS AND METHOD S Study Site slope of the highest point in both the state and GSMNP, Clingmans Dome. After reaching Elkmont, the river flows alongside Little River Road (Scenic TN 73) to the the main section of LR before exiting the park entrance at Townsend. After flowing 29 km within GSMNP the river continues through the towns of Townsend, Maryville, Alcoa, and Rockford before joining the Tennessee River. The LR watershed drains an area of approximately 980 km 2 Histo rically, human disturbance, including farming and logging related activities occurred within the present park boundary (Mast and Turk 1999). The area became an extremely profitable logging area during the first half of the 20 th century. The region was heavily clear cut, primarily by the Little River Lumber Company, and forest fires were also common. The Little River Railroad passed through many portions of the GSM, including the length of LR, to enable the transport of lumber. Logging ended in 1939 af ter ~60% of the area had been logged, after the formation of GSMNP (Madden et al., 2004). M any of the forests are still in successional stages (Madden et al., 2004). Since the first half of the 20th century, few large scale landscape alterations have occu rred in the park area adjacent to LR but human recreational use is common Spanning 2108 km 2 GSMNP is the most visited national park in the United States and receives over 9 million visitors each year. and fishermen year round and a large numbe r of swimmers, snorkelers, and inner tube
` 35 users during th e warmer months (Figure 2 1). Building temporary rock dams, disturbing rocks, and kayaking are other common activities in the str eam. The former logging railroad along LR was converted into heavily traveled Scenic TN 73 that serves as the main route between Cades Cove and Gatlinburg, TN. S eve ral concrete/ gravel parking lots and pull offs providing walking access to LR The river is still difficult to access near some p ull offs because of steep boulder covered slopes. Small amounts of treated wastewater are released into the river within GSMNP from a campground near Elkmont and an ed ucation center located next to Middle Prong Little River ( MPLR ) (Mast and Turk, 1999). D espite the long history of human use on the LR hellbenders still reside within the stream. Based on the results of previous studies (Nickerson et al., 2003; Freake, unpubl. data) hellbender surveys were conducted within an ~3 km section of the river (Fi gure 2 2) investigated by Nickerson et al (2002) and in portions of the MPLR to ensure capt ure of all three stage classes Elevation within the study area ranged from 327 407 m. Macroscopic in stream vegetation was rare The surrounding upland habitat was comprised primarily of pine and river cove hardwood forest (Madden et al., 2004). The area has a temperate climate, with high levels of precipitation. A five year precipitation mean at a similar elevation level withi n the park was measured at 147 cm (Shanks, 1954), and snowfall at lower elevations within the park is relatively infrequent in comparison to higher elevations. The average high temperature in nearby Gatlinburg, TN during the coldest month is 8.89C, white the low temperature averages 3.89C. High temperatures in the summer months average 27 29C.
` 36 Field Sampling Methods To locate C. alleganiensis diurnal skin diving surveys were conducted in LR during the summer and early fall months of 2008 2010 Ski n diving was chosen as the survey method due to its success in locating all stage classes of hellbenders (Nickerson and Krysko, 2003). Surveyors utilized snorkels and wetsuits to promote continuous surveying. On most occasions, one individual conducted s urveys, but occasionally groups of two to seven people assisted. The amount of time each individual surveyor spent searching for hellbenders was recorded. Surveyors worked upstream against the current to prevent visibility issues from displaced sand an d silt. Rocks were hand turned towards the surveyor to limit disturb ance to the streambed particles and replaced in their original position and orientation. Hellbenders encountered were captured by hand and placed in water filled plastic containers for d ata collection and tagging Rocks serving as shelter for hellbenders were marked temporarily by inscribing their surface with another rock to indicate the exact location of capture. TL and snout vent length (SVL) of each hellbender was measured in millime ters (mm) with the aid of a modified PVC pipe. The m ass of each individual was recorded in grams with an Ohaus CS2000 compact digital scale (Ohaus Corporation, Parsippany, NJ. USA). Sex was recorded if it could be determine d based on the swelling of mal e cloacal glands in August and Se ptember (Nickerson and Mays, 1973) Hellbenders were individually marked to ensure future identification. Biomark 9mm and 12.5mm Passive Integrated Transponder (PIT) tags (Destron Fearing, South Saint Paul, MN, USA) were injected in adult and most sub adult individuals dorsally near the base of the tail. New Skin liquid bandage (Prestige Brands, Inc., Irvington, NY, USA) was appli ed
` 37 at injection sites. Unique individual combinations of Visible Implant Elastomer (VIE) (Northwest Marine Technology, Inc., Shaw Island, WA, USA) were injected in individuals too small for PIT tag injection. PIT tag needles were disinfected with 70% eth anol between uses, while VIE needles, if used multiple times, were sanitized with rubbing alcohol wipes. Diet samples from larval C. alleganiensis were collected using the Easy Feeder Nipple Tip Syringe (Four Paws Products, Ltd., Hauppauge, NY, USA) and r iver water to flush out stomach contents. Contents were pre served in either 70% ethanol or buffered 10% dilution of concentrated formalin. Individuals were returned to their exact capture site following data collection, and GPS localities were recorded u sing an eTrex Legend or GPSMAP 76CSx (Garmin International, Inc., Olathe, KS, USA). Microhabitat parameters were measured directly at the point of capture. Water measure d using the Combo pH/EC/TDS/Temperature Tester with Low Range EC and Watercheck pH and TDS reader (HANNA Instruments Woonsocket, RI, USA). Flow was recorded with a Global Water Flow Probe (Global Water Instrumentation, Inc., College Station, TX, USA). Water depth and shelter size, defined as the longest length of the she lter rock, was also recorded. A sample of the streambed particles under each shelter rock were measured using the Federal Interagency Sedimentation Project (FISP) US SAH 97 sediment siz e analyzer, also known as a gravelometer. Streambed particle composition and the mean particle size (D50), representing the particle size where 50% of stream particles are equal to or less than the value, of the riffles within the LR study area was determi ned following the general protocol of the Wolman Pebble Count (Wolman, 1954). TDS, water depth, and streambed particles
` 38 were measured within the study a rea at fifty random localities chosen with the aid of a random number table. Prey abundance was measur ed by calculating crayfish relative frequencies as in Nickerson et al. (2003). During some survey periods in 2009, the number of rocks turned and the number of crayfish encountered underneath the rocks was counted to calculate the percentage of rocks harb oring crayfish. T o determine a rough index of human recreational use in LR, individuals using inner tubes on the river were counted during a half hour period on seven occasions during summer 2010. Data Analysis All statistical analyses were completed using Microsoft Excel for Mac (2008) and Program R (version 2.12.2) (R Development Core Team, 2008) Significance levels for all tests were set at =0.05. Data from Nickerson et al. (2003) as well as unpublished re sults from studies by the Knoxville Zoo, University of Tennessee Knoxville, and Lee University were combined with results of this study to investigate population structure and dynamics over a 10 year period (Phil Colclough and Marcy Souza, unpubl. data use d with permission; Michael Freake, unpubl. data used with permission). S earch effort was calculated as the number of person hours required to locate one hellbender Mean mass and TL of hellbenders sampled across all years was calculated. Histograms of an nual and combined C. alleganiensis size class distribution in LR were constructed based on individual TL. All histograms used 25 mm intervals. Recaptured hellbenders were only represented once in the combined histogram, but only individuals recaptured wi thin a single year were eliminated from the yearly histograms. To determine if the size distribution of hellbenders was statistically different from a representative sampled population, TL data were compared to data from one of most
` 39 well studied hell bender streams, North Fork of White River (NFWR), MO (Nickerson and Mays, 1973 ). Data from the 1969 NFWR population were used for this comparison because the population has since experienced substantial declines (Wheeler et al. 2003; Nickerson and Briggl er 2007), and these data are the best available baseline. To reduce potential bias from unmarked individuals in LR data from only the two years with the largest sample sizes that were not directly impacted by flooding (2006 and 2008) were used for analysis. Data were tested against the NFWR historical data using two sample boot strap Kolmogorov Smirnov tests. The k s.boot function, from R Package 2011), tested whether probability densities for TL data from the two rivers were the same. Individual hellbenders were also classified into stage classes using TL. Based on previous research, individuals <125 mm in TL, both gilled and non gilled, were classified as larvae (Bishop, 1941; Nickerson and Mays, 1973). Larvae were also classified into first (<90 mm TL) and second year ( > 100 mm TL) age classes for shelter size analysis based on previous studies and the results of surveys in LR (Smith, 1907; Bishop, 1941). I ndividuals between 90 100 mm TL could not be classified to an age class and were therefore not used in analysis comparing larval age classes. Previous research suggests that size at sexual m aturity differs among sex and locality, but generally ranges from 300 390 mm TL (Dundee and Dundee, 1965; Taber et al., 1975; Peterson et al.,1988). While most animals captured during this study period could not be sexed, one small male of 285 mm TL was d etermined to be sexually mature because of a swollen cloaca during late summer. Due to this capture as well as the general lack
` 40 of larger adults in LR, sexual maturity was estimated at 275 mm TL. All individuals measuring 125 275 mm TL were considered su b adults. Microhabitat data, including water quality and shelter parameters were analyzed using descriptive statistics, linear regression, Analysis of Variance (ANOVA), Kruskal Wallis rank sum tests, and t tests. Unpublished data on shelter size taken by Dr. Michael Freake was included with permission in all analyses on shelter size. Linear regressions were used to examine the relationship between shelter size, water depth, and water temperature at capture site and hellbender TL. These parameters were al so compared among life stages. As water depth and larval shelter size data were not normally distributed, these parameters were tested using Kruskal Wallis rank sum tests. The remaining parameters were evaluated using ANOVA and t tests. In order to cont rol pairwise test of means. Therefore the results of t tests comparing means of habitat variables among stage class groups were only considered s ignificant if p<0.0167. Al l streambed particle sizes were classified into categories according the Wentworth particle scale (Appendix ) (Wentworth, 1922) Due to the low presence of some categories, all particles <4 mm were combined into one category, and large and very large cobbl e counts were also pooled before the data was used for statistical analysis. The presence/absence of streambed particle size at the site of capture was compared among stage classes using an ordinal logistic regression. Presence/absence of particle catego ries at used sites was also compared to presence/absence of particle categories at random locations using a binary logistic regression model.
` 41 To evaluate the effect of prey abundance on hellbender body condition combined data from four studies completed in LR since 2000 were compared to ata from 2004 2010 surveys of Hiwassee River (HR), TN (Phil Colclough and Marcy Souza, unpubl. data; Michael Freake, unpubl. data). These rivers wer e chosen because of their differences in prey availability based on crayfish relative frequencies. All TL measurements were transformed by cubing and then dividing by 10,000 to linearize the relationship of TL and mass. Linear regressions of transformed TL vs. mass from LR were compared to data from the two other rivers using an alysis of covariance (ANCOVA). Diet samples were analyzed using a Bausch and Lomb 0.75 3.0X binocular microscope, and identified to the lowest possible taxonomic level based on the condition of the samples. Due to the small sample size, no statistical analysis was conducted.
` 42 Figure 2 1. Human recreational use on Little River, TN in Great Smoky Mountains National Park. Photo co urtesy of Kirsten Hecht Kardasz.
` 43 Figure 2 2. Study site (Little River, TN; USA). Photo courtesy of Kirsten Hecht Kardasz.
` 44 CHAPTER 3 RESULTS General Results During my study from 2008 2010, a total of 125 hellbenders including 55 adults, 29 sub adult s, and 41 larvae were captured over 394 total survey hours Three larval sized individuals had lost their external gills. Survey effort varied among years, but averaged 2.88 hours per hellbender capture in the main portion of LR. In the MPLR, a search effort of 7.73 survey hours per hellbender capture was noted in all surveyed areas, but hellbenders were only located in one riffle which had a survey effort of 2.91 hours per capture. True effort may be slightly lower than recorded as people using inner tubes on the river often interrupted surveying efforts. During five total hours of sampling, 281 tubers were counted in LR. The mean rate was ~1 tuber passing per minute but vari ed from 0.43 to ~3 per minute. Eight hellbenders were recaptured during my s tudy period. Only one recaptured individual was initially marked during my s tudy. This sub adult was relocated several days after its initial capture within 1 m of the original capture site. One individual from the original study by Nickerson et al. (20 02 ) was relocated in the same riffle and had grown from a sub adult (197 mm TL) to an adult with a TL of 360 mm. The remaining recaptures were all individuals tagged in other studies within LR since 2004. Population Structure During all surveys from 2000 2010, there were 533 total hellbender captures (168 larvae, 159 sub adults, and 206 adults) including 33 recaptures of 27 individuals. 356 individual hellbenders were tagged. Sex was determined for 38 individuals (23 males; 15 females). Mean TL for hellbenders across all years in LR (n=500) was 218.1
` 45 mm ( 130.1) The combined histogram of size class distributions during the decade revealed an overall stable population structure with a sharp decline from the 50 75 mm class to the 75 100 m m class (Figure 3 1). Larval sized individuals represent ed 25% of the total captured individuals among all years. Size class distribution varied among years but larvae were generally abundant (Figure 3 2). Hellbender size class distributions from LR in 2006 (n=113) and 2008 (n=117) were statistically different from the 1969 NFWR population (n=478) (Figure 3 3 ) based on results of Kolmogorov Smirnov bootstrap tests (D=0.584, p<0.001; D=0.284, p<0.001) Microhabitat All physical parameters were measured a t the point of capture. Average pH at the site of capture was 7.23 (n=95). With a small sample size (n=12), capture site stream flow ranged from ranged from <0.5 to 1 m/s with a median value of 0.5 m/s. Although regression analysis suggested a linear re lationship between hellbender TL and water temperature (n=102) was present, water temperature was not a strong predictor of hellbender TL (R 2 =0.042; p=0.039) (Figure 3 4). Linear regression analysis also revealed no relationship between hellbender size (T L) and water depth (n=104) (R 2 =0.024; p=0.12) (Figure 3 5), but a weak correlation between hellbender TL and shelter size (n=217) was noted (R 2= 0.266; p<0.001) (Figure 3 6). Additional tests revealed no significant difference in average water depth or tem perature among stage classes. Although overall shelter size among the stage classes overlapped, average shelter size differed significantly among stage classes (F(2, 214)=32.82; p<0.001) (Figure 3 7; Figure 3 8). Using t tests, mean shelter size of larvae (n=61) was significantly different from both adults (t = 8.11, df = 159, p value = <0.001) and sub
` 46 adults (t= 4.83, df = 115, p value = <0.001). Sub adults (n=56) and adults (n=100) also differed significantly in mean shelter size (t = 2.55, df = 154, p value = 0.012). There was no statistical difference between mean shelter size between first and second year larvae in LR. However, first year larvae utilized some larger shelter sizes, including one of 1085 mm while the largest shelter size of second yea r larvae was 610 mm. One individual of 90 mm TL found beneath a 1286 mm boulder could not conclusively be categorized as first or second year larvae. Results of pebble counts conducted within the riffles of the study area showed the D 50 value in the small cobble category (64 90 mm) (Figure 3 9). Streambed particle classes under shelter rocks of larvae (n=25), sub adults (n=26), and adults(n=38) (Figure 3 10) did not differ significantly (Table 3 1). However, when comparing random samples to locations of capture (Figure 3 11), hellbenders appear ed to utilize shelters underlain at least partially by very coarse gravel more than would be expected by chance based on the results of the logistic regression model (Ta ble 3 2). This model also showed a negative a ssociation between hellbender use and rock shelters overlaying fine gravel. Based on correlations between streambed particle size categories, an additional model was tested combining all particles smaller than 32 mm into one category, which listed very co arse gravel as the only significant variable (Table 3 3). Body Condition Mean mass of all LR he llbenders (n=494) was 115.1g ( 142.5), but was influenced by the large number of larval individuals. Mean mass of adults (n=183) was 266.6 g ( 128.3). Although individuals often appeared thin, most hellbenders appeared to be in good overall health with few injuries. Common abnormalities were minor and
` 47 included missing/extra digits and scars. A few captured individuals presented with toe malformations. Only a very small number of potentially serious abnormalities such as ulcers and severe limb injuries were noted (Figure 3 12). Crayfish relative frequencies in LR were low, ranging from 2 16% (mean=6.8%). At the NFWR site crayfish relative frequencies were considered high during the study period in 1969 and ranged from 56 67%, while the average mass of hellbenders (n=463) was 371.3 g ( 240.4 ) (Nickerson and Mays,1973). Crayfish relative frequencies in HR ranged from 21 28.5% with a mean of 24.7%, and h ellbender mass (n=414 ) averaged 139.9 g ( 123.6 ) (Phil Colclough, unpubl. data; Michael Freake, unpubl. data). Results of linear regression analysis of body condition in the three rivers are listed in Table 3 4. An ANCOVA comparing linear regression lines of body conditions in all three rivers (Figure 3 13) was significant (F(2, 1490)=137.8, p<0.001). Individual pair wise compariso ns of hellbender body condition in the three populations confirmed that the linear regression slope of LR was sig nificantly di fferent from both NFWR (F(1,986)=194.6, p<0.001) and HR (F(1, 1029)=16.6, p<0.001). The slope of hellbende r body condition in HR was also significantly different from the slope o f hellbender body condition in NFWR (F(1,965)=92.5, p<0.001). LR had the sma llest expected mass per adjusted tot al length of the three rivers. Larval Diet A total of 23 larval diet samples were collected. Larval diet samples contained primarily larval staged aquatic insects, but crayfish were also identified (Table 3 5). Epheme roptera and Trichoptera were the most common insect orders consumed by larval C. alleganiensis sampled in LR (Figure 3 14). Crayfish were also regularly consumed. The only vertebrate diet item noted was a ~40 mm TL Eurycea salamander
` 48 larvae regurgitated by a 50 mm TL hellbender larvae. Plant matter and gravel also presented in the samples. One sample from a sub adult (204 mm in TL) was identified as an Ephemeroptera nymph (family Heptageniidae).
` 49 Table 3 1. Variable estimates and odds ratios from an ordinal logistic regression model based on streambed particle size classes at sites used by larval (n=25), sub adult (n=26), and adult (n=38) hellbenders ( Cryptobranchus alleganiensis ) captured in Little River, TN Variable Estimate Standard error Wald statistic (Z) p value Odds ratio <4 mm 1.07 1.37 0.78 0.44 2.91 Fine gravel 0.61 1.13 0.54 0.59 1.84 Medium gravel 0.35 0.54 0.66 0.51 0.70 Coarse gravel 0.31 0.49 0.64 0.52 0.73 Very coarse gravel 2.14 1.19 1.79 0.07 8.50 Small cobble 0.54 0.43 1.26 0.21 0.58 Medium cobble 0.40 0.50 0.80 0.42 0.67 Large/very large cobble 0.38 0.52 0.73 0.47 0.68
` 50 Table 3 2. Variable estimates and odds ratios from a binomial logistic regression model based on streambed particle size classes at sites used by hellbenders ( Cryptobranchus alleganiensis ) (n=89) and random locations (n=50) within Little River, TN. Variable Estimate Standard error Wald statistic (Z) p value Odds r atio Intercept 0.75 0.75 1.00 0.32 0.47 <4 mm 1.36 0.81 1.68 0.09 0.26 Fine gravel 1.85 0.71 2.62 0.01 0.16 Medium gravel 0.27 0.58 0.46 0.64 0.76 Coarse gravel 0.93 0.54 1.72 0.09 2.54 Very coarse gravel 1.57 0.64 2.47 0.01 4.83 Small cobble 0.17 0.48 0.36 0.72 0.84 Medium cobble 0.24 0.57 0.42 0.68 1.27 Large/very large cobble 0.97 0.68 1.43 0.15 2.65
` 51 Table 3 3. Variable estimates and odds ratios from a binomial logistic regression model based on streambed particle size classes (with particles <32 mm combined into one category) at sites used by hellbenders ( Cryptobranchus alleganiensis ) (n=89) and random locations (n=50) within Little River, TN. Variable Estimate Standard error Wald statistic (Z) p value Odds ratio Intercept 1.93 0.70 2.78 0.006 0.15 <32 mm 0.17 0.49 0.34 0.73 1.18 Very coarse gravel 2.67 0.55 4.83 <0.001 14.43 Small cobble 0.21 0.44 0.49 0.63 1.24 Medium cobble 0.32 0.52 0.62 0.54 1.38 Large/very large cobble 0.86 0.62 1.39 0.17 2.36
` 52 Table 3 4. Variable estimates and model fit for linear regressions of hellbender ( Cryptobranchus alleganiensis ) body condition (mass (g) vs. transformed total length (mm)) in three rivers. Variables Estimate Standard error t p R 2 F( df ) p Little River, TN 0.91 5392 (1, 525) <0.001 Intercept 3.63 2.45 1.49 0.14 Transformed total length (mm) 0.050 0.0007 73.43 <0.001 Hiwassee River, TN 0.92 5975 (1, 504) <0.001 Intercept 12.40 2.44 5.08 < 0.001 Transformed total length (mm) 0.054 0.0007 77.30 <0.001 North Fork of White River MO 0.91 4419 (1, 461) <0.001 Intercept 15.55 6.36 2.44 0.02 Transformed total length (mm) 0.067 0.001 66.47 <0.001
` 53 Table 3 5. Contents of diet samples taken from larval hellbenders ( Cryptobranchus alleganiensis ) in Little River, TN Sample TL(mm) Mass(g) Contents 1 65.0 2 1 Trichoptera; Gravel 2 66.0 2 2 Trichoptera (2 Polycentropodidae; 1 Polycentropus ) 3 70.0 3 1 Ephemeroptera (Heptageniidae); 1 Crayfish; Plant Matter 4 70.0 2 1 Unknown 5 74.0 3 4 Ephemeroptera (1 Heptageniidae; 2 Baetidae); 1 Plecoptera (Perlidae) 6 78.0 3 1 Ephemeroptera (Heptageniidae); 1 Trichoptera (Polycentropodidae; Polycentropus ); 1 Unknown; Plant Matter 7 78.0 3 1 Ephemeroptera; 1 Plecoptera (Leuctridae) 8 77.0 4 2 Ephemeroptera (1 Heptageniidae); 1 Plecoptera 9 66.0 2 1 Unknown Insect; 1 Unknown; Plant Matter 10 75.0 3 1 Ephemeroptera 11 73.0 3 1 Ephemeroptera; 1 Trichoptera(Hydropsychidae); 1 Unknown 12 63.0 2 1 Plecoptera (Perlidae) 13 63.5 2 1 Unknown; Gravel 14 69.0 2 1 Crayfish 15 70.0 2 1 Trichoptera; 1 Diptera 16 60.0 2 1 Ephemeroptera(Heptageniidae); 1 Unknown; Gravel 17 60.0 2 2 Ephemeroptera (Heptageniidae); 1 Crayfish 18 73.0 2 1 Diptera; 1 Crayfish 19 62.0 2 1 Coleopter a (Adult Elmidae), Gravel 20 118.0 9 2 Unknown (1 possible crayfish/1 insect) 21 76.0 3 2 Ephemeroptera 22 40.0 4 1 Trichoptera 23 50.0 3 1 Eurycea larvae
` 54 Figure 3 1. Histogram of size distribution of captured hellbenders ( Cryptobranchus alleganiensis ) from 2000 2010 in Little River, TN (n=500)
` 55 Figure 3 2. Yearly size distribution histograms of captured hellbenders ( Cryptobranchus alleganie nsis ) from 2000 2010 in Little River, TN.
` 56 Figure 3 3 Comparison of hellbender ( Cryptobranchus alleganiensis ) size class distributions sampled from Little River, TN in 2006 (n=113) and 2008 (n=117), with the North Fork of the White Rive r, MO in 1969 (n=478)
` 57 Figure 3 4. Scatter plot with linear regression line of water temperature ( C) vs. hellbender total length (mm) in Little River, TN (n=102)
` 58 Figure 3 5. Scatter plot with linear regression line of water depth (mm) vs. hellbender total length (mm) in Little River, TN (n=104)
` 59 Figure 3 6. Scatter plot with linear regression line of shelter size (mm) vs. hellbender total length (mm) in Little River, TN (n=217)
` 60 Figure 3 7. Box plots comparing shelter size (mm) amon g three hellbender stage classes larvae (n=61), sub adults (n=56), and adults (n=100), in Little River, TN
` 61 Figure 3 8. Bar graph showing mean standard error of the mean (SEM) for shelter size (mm) used by three stage classes of hellbenders larvae (n=61), sub adults (n=56), and adults (n=100), in Little River, TN. Bar graphs with different letters above are significantly different (p<0.05).
` 62 Figure 3 9. Results of Wolman pebble count survey in Little River, TN showing streambed particle s ize distribution in Little River, TN (D50=small cobble).
` 63 Figure 3 10. Bar graph comparing streambed particle size categories found below shelter rocks among hellbender stage classes larvae (n=25), sub adults (n=26), and adults (n=38) in Little River, TN.
` 64 Figure 3 11 Bar graph comparing streambed particle size categories found at sites used by hellbenders (n=89) and random locations (n=50) in Little River, TN.
` 65 Figure 3 12. Examples of abnormalities of Cryptobranchus alleganiensis captured in Little River, TN. Photos courtesy of Kirsten Hecht Kardasz.
` 66 Figure 3 13. Scatter plot with regression lines comparing body condition of hellbenders ( Cryptobranchus alleganiensis ) from three rivers (Little River, TN (n=527) ; Hiwassee River, TN (n=507) ; North Fork of the White River ; MO (n=463 ) with differing crayfish relative frequencies.
` 67 Figure 3 14. Pie chart of total food items identified from larval hellbender ( Cryptobranchus alleganiensis ) diet samples (n=23) taken from Littl e River, TN.
` 68 CHAPTER 4 DISCUSSION Population Structure This study sought to examine the influence of geomorphology on the population structure of Cryptobranchus alleganiensis by examining several factors: microhabitat use and diet among stage classes, and the comparison of body condition of individuals in streams with different crayfish relative frequencies. However, an understanding of the overall population structure, parti cularly over time, was needed to verify that the LR population was in fact unique from the majority of studied populations before potential mechanisms affecting the p opulation could be examined. Overall, the LR population appears stable over the last decade with regular recruitment of young individuals and representation of all size classes. Consistent with the r esults of Nickerson et al. (2002 ) larvae represented a significant proportion of the population both overall, a nd in individual years. Although more adults were captured than by Nickerson et al. (2002), the general trend regarding large adults remained with only a handful of individuals over 450 mm captured. Comparing these results directly to historical data tak en f rom NFWR in 1969 illustrated the differences in the LR population from a well studied C. alleganiensis population structure. Despite a slightly larger sample size, researchers still captured fewer adults in every size interval in LR than the NFWR in 1 969 (Figure 4 1) The distribution differences between the two rivers are particularly apparent in hellbenders over 475 mm TL. However, it remains unclear whether these observations truly represent differences in population structure or are due to differ ences in detectability.
` 69 Results from this study suggest that larvae in LR are primarily utilizing cobble and boulder for shelter. Unlike other rivers where larvae have been located within gravel beds, larval hellbenders in LR can be sampled easily using s tandard skin diving methods (Nickerson and Krysko, 2003; Nickerson et al., 2003). Hellbender researchers habitats such as gravel beds associated with larval hellbenders. A recent study in the Alleghen y River drainage of New York found that despite a decrease in the density of C. alleganiensis at study sites within the last 20 years, more individuals <20 mm were captured recently than in the 1980s presumably because of methods specifically targeting the se size classes (Foster et al., 2009). It is also unclear how deep larvae may reside within gravel beds in other localities so many larvae may not be accessible even with methods specifically targeting their habitat. Therefore larval hellbenders are pote ntially present in other studied sites, but may not be adequately represented in the sample due to low detectability rates. Larger adults may also avoid detection in LR. Due to the density of rocks and the presence of very large boulders that could not b e lifted, many individuals may have been missed during surveys. In addition, deep pools, which have been known to house hellbenders were not surveyed (Green, 19 33; Nickerson and Mays, 1973). Recent studies conducted in the Blue Ridge Province have also p roduced young C. alleganiensis (Maxwell 200 9; Burgmeier et al. 2011 b ; Groves and Williams 2011; Freake, unpubl. data) Approximately 21% of hellbenders captured during surveys in HR within the boundary of the Cherokee National Forest in Tennessee were larval sized individuals (Freake, unpubl. data). Shor t surveys in the Pigeon River of North Carolina produced three larvae out of only six individuals captured
` 70 (Maxwell, 2009). La rvae have also been located in n orthern Georgia and additional areas in western North Carolina (Burgmeier et al. 2011b; Groves and Williams, 2011). These Blue Ridge populati ons also do not appear to be impacted by disease and/or serious abnormalities ( Gonynor et al. 2011; Groves and William s, 2011; Souza unpubl. data) as in other regions (Hiler et al. 2005; Miller and Miller 2005; Nickerson et al. 2009). Due to geology, topography, and history, the Blue Ridge Province, which has the highest proportion of interior forest habitat in the Southern Appalachia n region, remains 80% forested (SAMAB 1996a, 1996b). Relatively large portions of the Blue Ridge, including the greates t concentration of public lands in the eastern United States, are now protected due to aesthetics and ecological value (SAMAB 1996a, 1996b) (Figure 4 2 ). Therefore, the abundance of larvae seen throughout the Blue Ridge Province may be partially due to a decrease in factors suspected in hellbender declines such as siltation, channelization, agriculture, mining, logging, and pollution (Dundee, 1971; Nick erson and Mays, 1973; Bury et al., 1980). Recent studies by Groves and Williams (2011) noted a negative correlation between human development and hellbender densities, but the finding was not statistically significant. M any C. alleganiensis populations i n eastern West Virginia Appalachian Plateau and Valley and Ridge regions appear to be declining, with the except ion of some located within the protected Monongahela National Forest (Keitzer, 2007). This supports the hypothesis that human disturbance, ra ther than geology alone, may have a major influence on hellbender populations.
` 71 Although size classes we re relatively well represented in LR across all years, some we re absent or low in abundance during individual years. Water regimes can influence the pop ulation structure of stream dwelling amphibians by affec ting mortality and recruitment ( Metter, 1968 ; Duellman and Trueb, 1986 ). Flooding events influenced the long term population structure of Ascaphus truei in unprotected streams in Idaho and Oregon by almost completely eliminating tadpoles and thus reducing recruitment in certain years (Metter, 1968). Flooding has also been suspected as a source of mortality and displacement in hellbenders (Wiggs, 1977; Trauth et al., 1992; Humphries, 2005; Miller and Miller 2005; Nickerson et al. 2007), but its influence on popula tion dynamics remains unclear. Nickerson et al. (2007) noted that following floods in 2003, no individuals were captured within MPLR the following ye ar despite previously locating four larva e in only eight hours of searching. Second year larvae were also absent from the main portion of the LR in 2004 (Freake, unpubl. data). In 2005, Freake captured no individuals from 125 150 mm, and only a very small number of individuals from 150 200 mm T L Additional small scale flooding events in 2009 correlated with a missing stage class the following year: small sub adults from 125 150 mm TL. Nickerson et al. (2007), which examined the potential impacts of flooding on hellbenders in MPLR, cited USGS ( 2001) stream flow readings from station 03497300 beginning in 1997. An examination of peak stream flow data taken at the LR station prior to 1997 revealed an extreme flooding event in 1994, where peak stream flow was over 26,00 0 cfs (Figure 4 3 ). N o data on C. alleganiensis populations in LR are available prior to 2000 to illuminate the effects of the flood on hellbender population
` 72 of year brown trout ( Salmo trutta ) and few young of year rainbow trout ( Oncorhync h us mykiss ) following the 1994 flooding, suggesting that other taxa may have been affected by the flooding (Kulp, 2011). It is therefore possible that this extreme flooding event had a substantial impact on the hellbenders in LR, and potentially contributed to the lack of large individuals seen in the river today. As C. alleganiensis growth ra tes decelerate with age (Taber et al., 1975; Peterson et al., 1988) and hellbender growth data is not available from LR, it is difficult to follow cohorts in LR across subsequent years to monitor the long term effects of low recruitment durin g a particular year. However, two under represented size classes marked correlating with flooding events in 2003 and 2009. C urrent extremes may be an important influence on hellbender recruitment in LR that could lead to long term i mpacts on the population structure of hellbenders. Potential reductions in recruitment following flooding events could be related to larval C. alleganiensis habitat use within LR. Microhabitat The examination of C. alleganiensis microhabitat associations in this study required two main assumptions: 1) Hellbenders closely correlate d to the microhabitat at diurnal capture sites for significant time periods and 2) The micro habitat at capture sites remained relatively constant through time. To satisfy the fir st assumption, it is pivotal that hellbenders regularly inhabit, rather than temporarily utilize, shelters. Aggressiveness towards intruding conspecifics and the rarity of shared shelters outside of the breeding season suggests that adult hellbenders may be territorial over shelter rocks (Smith, 1907; Hillis and Bellis, 1971; Nickerson and May, 1973). Wiggs (1977)
` 73 estimated that at least 93% of captured hellbenders at his site were in their home riffle, indicating that transitory individuals are rare. Ad ult C. alleganiensis have relatively small home ranges and exhibit site fidelity (Hillis and Bellis, 1971; Nickerson and Mays, 1973; Wiggs, 1977; B all, 1992; Blais, 1996). Radio telemetry studies have commonly found hellbenders utilizing one or two indivi dual shelters for months (Wiggs, 1977; Ball, 1992; Blais, 1996), and often homing to their original riffles and shelters when displaced (Hillis and Bellis, 1971; Wiggs, 1977; Blais, 1996), even following months of captivity (Nickerson, 1980). However, sea sonal changes in habitat use have been noted in some localities (Smith, 1907; Green, 1933; Nickerson, 1978; Ball, 2001). A radio telemetry study by Ball (2001) found that hellbenders in a North Carolina stream typically used two boulder shelters throughout the year: one in shallow water during the spring and summer, and a larger one in a deep pool possibly to overwinter. Green (1933) noted that C. alleganiensis in West Virginia move d to deep pools during summer months, presumably due to temperature increas es, while hellbenders in a substantially spring fed Missouri stream moved from pools to rif fles during the same time perio d (Nickerson, 1978 ). Some authors have suggested that hellbenders may move long distances during breeding periods (Smith, 1907). However, movements of hellbenders in a North Carolina stream were less frequent and shorter in distance during the summer and fall months. Due to these seasonal vari ations, this study only attempted to ass ess diurnal microhabitat associations of hellbende rs during the studied seasonal period (i.e. summer and early fall). While a majority of studies support an extended association of adult hellbenders to specific seasonal habitats, information regarding movement, activity, and site fidelity of
` 74 immature hell benders is extremely limited. To my knowledge undisturbed larvae and small sub adults in situ have never been observed in the open. It is unclear whether C. alleganiensis larvae are nocturnal or diurnal in the wild although Smith (1907) noted that hatch lings avoided light. While it is also not known whether hellbender larvae in the wild ever leave shelter to forage, amphibian larvae commonly reduce activity levels in the presence of predators, including cannibalistic conspecifics (Colley et al., 1989) w hich are abundant in LR. In addition macro invertebrates found in larval hellbender diets during this study are plentiful beneath rocks in LR, thus low larval hellbender activity would be expected. Larvae presumably overwinter at male guarded nest sites, and are believed to disperse sometime in spring or early summer (Bishop, 1941), prior to the seasonal timeframe of this study. Larvae and sub adults were almost entirely solitary during this study, opening the possibility that young hellbenders also beco me territorial soon after dispersing from the nest. While it is not unreasonable to assume that young hellbenders, like adults, are associated with microhabitats for extended periods, it cannot be confirmed and therefore the results of this analysis shoul d be interpreted with caution. No correlations between hellbender TL or stage class and measured water quality parameters were noted. Microhabitat parameters were assumed to be relatively constant through time. Water parameters including pH and TDS show ed little temporal or spatial variation during the survey period, but as LR is fed by surface water, water depth and water temperate varied considerably due to fluctuations in precipitation. Therefore, this study cannot conclusively rule out the effects o f water d epth and water temperature on hellbender habitat use.
` 75 While hellbender stage classes in LR were captured in sites similar in pH, TDS, water depth, and temperature, the physical habitat used by larval hellbenders in LR might increase their susceptibility to flooding. One of the most important factors affectin g stream species is current (Giller and Malmqvist, 1998). Organisms must find ways to adapt to stream flow, particularly during flooding conditions, due to sheer forces and energy considerations. While stream organisms typically adapt a suite of characte ristics to help them survive in normal currents, these adaptations are typically inadequate during periods of intense flow. Many organisms survive spates by seeking refugia (Giller and Malmqvist, 1998), including the interstitial spaces in the benthic lay ers, where larval C. alleganiensis have been located in other localities (Smith, 1912; Nickerson and Mays, 1973; Nickerson et al. 2003). As this habitat is not available to larval hellbenders in LR due to sandstone bedrock breaking down into sand and fil ling these spaces, larvae are utilizing the space under rocks at the surface of the streambed which may be less secure during flooding periods. While larvae utilized a wide variety of shelters in LR their habitat included much smaller shelter sizes than other stage classes including medium to very large cobble, and the average shelter size used by larvae was significantly smaller than sub adults and adults. Smaller shelters may be moved easily by increased water current, increasing the risk of the hellbe nder larvae underneath being crushed, swept away in the cur rent, or exposed to predators. The use of refugia is also a common strategy to reduce predation risk. In cannibalistic species, such as C. alleganiensis shifts in habitat use among size or stage classes is a common adaption to reduce mortality of young individuals by intraspecific predation (Foster et al. 1988). In other localities, hellbender larvae have been
` 76 associated with completely separate habitat from their adult counterparts, such as the interstitial spaces within the gravel beds (Smith, 1912; Nickerson and Mays, 1973; Nickerson et al., 2003; Foster et al., 2009). As this typical larval habitat in other rivers is unavailable in LR, larvae are instead utili zing similar habitat to adults: a wide size range of rocks at the riverb ed surface. This wide range of shelter sizes used by larvae includes a direct overlap in shelter size with sub adults and adults, which may be partially due to some young individuals dispersing from their site of hat ching later than others. Young hellbenders may remain in nesting sites for prolonged periods, as larval hellbenders have been observed at guarded nest sites in May and June (Jeff Humphries, unpubl. data). Second year larvae may be more selective in their choice of shelter size due to experience with predators. Despite the wide range of shelter sizes utilized by larvae in LR and the overlap of larval shelter type with older stage classes, there is a shift in average shelter size used among stage classes. Therefore it appears that an ontogenetic shift in hellbender habitat use still occurs in LR despite the similar habitat type among stage classes, which may serve as a form of refugia against intraspecific predation. T he relationship, although weak, of she lter size and hellbender TL found during this study is notable because previous studies examining habitat use by hellbenders have found no association between shelter size and hellbender size (Hillis and Bellis, 1971; Humphries and Pauley, 2005). However, these studies have focused primari ly on adult sized hellbenders. A correlation was found between hellbende r total length and
` 77 shelter size when examining shelter use in a hellbender population with many young individuals. Like shelter size, other studies have examined the role of streambed particle size on the occupancy of C. alleganiensis but have been unable to compare streambed particle association among stage classes. Most studies have focused on general categories of particles rather than the more fine scale categories used in this study. Previous studies have found a general association between gravel and cobble substrates and hellbender occupancy (Keitzer, 2007; Maxwell 2009; Burgmeier et al., 2011a). These types of streambed particles are known to harbor a number of salamander species including hellbender larvae (Smith 1912; Nickerson and Mays, 1973; Tumlinson et al., 1990) and also serve as important macro invertebr ate habitat (Giller and Malmqvist, 1998; Hwa Seong and Ward, 2007), which represent the most utilized food source for hellbenders of all sizes. Due to the lack of gravel bed habitat in LR, the interstitial spaces among the gravel, cobble, and boulders be neath the larger shelter rocks may be particularly important to hellbender larvae for additional protection and food access to smaller food items. However, most larvae were found directly under shelter rocks rather than underlying cobble or gravel, and no difference in stream particle sizes below shelter rocks was noted among the stage classes. This suggests that although the stream particle sizes associated with shelters may still be important for larval refugia, other factors might be influencing habita t selection by hellbenders in relation to substrate beneath shelter sites.
` 78 Comparing streamb ed particle sizes at sites utilized by hellbenders of all stage classes to randomly sampled localities revealed a negative association of occupancy with fine gravel and a positive association of occupancy with very coarse gravel. It is unclear if these associations are due to habitat preference s and/or prey availability, or are simply related to space availability beneath shelter rocks. Smaller streambed particles could fill in the spaces underneath rocks, embedding them and leaving no area available for hellbenders to occupy. Stream embeddedness has been negatively associated with the presence of other species of salamanders (Tumlinson and Cline, 2003). Converse ly, boulders or large cobble may leave too much space available beneath shelter rocks, leaving hellbenders with reduced protection from stream flow, predators, and con specifics. The association of shelters used by hellbenders and medium sized particles, like very coarse gravel, may represent a balance of space availability and protection as well as food availability. Body Condition The c omparison of linear regression lines of hellbender body condition in three rivers with different crayfish relative fre qu encies (NFWR, LR, and HR) suggests that the relative frequency of crayfish in the rivers correlates with overall body condition of C. alleganiensis Crayfish relative frequency values appear to corroborate the observations of Bouchard correlating crayfi sh abundance with streambed rock composition. The streambed of NFWR, the only stream largely influenced by carbonate rock, is mostly a mixture of chert, dolomite, and sandstone (Nickerson et al., 2003). Hellbenders in the NFWR, which had high crayfish re lative frequencies, had a higher expected mass at a given total length than LR, which possessed comparatively low crayfish relative frequencies. HR, which had the middle cray fish relative frequency
` 79 measure of the three rivers, also had the middle expected hellbender mass at a given total length. The HR study site lies within the Sandsuck Formation of the Walden Creek Group and is comprised primarily of shale, sandstone, an d quartz pebble conglomerate. A recent study on the nutritional content of crayfish from MO revealed that crayfish are high in proteins and fatty acids, but extremely low in fat content (Dierenfeld et al., 2009). Despite the low metabolism of hellbenders, the low fat content of crayfish could lead to an overall reduction in body conditio n at sites with significantly fewer crayfish. Recent studies in NFWR revealed an overall decrease in crayfish relative frequencies since 1969 (Nickerson et al., 2009), but no significant reduction in overall hellbender body condition during the last 20 ye ars (Wheeler et al., 2003). However, crayfish relative frequencies are still relatively large in comparison to both LR and HR. While these results in regard to body condition are noteworthy it is not known whether a decrease in body condition has any im pact on overall survival in hellbenders. As hellbenders experience indeterminate growth, crayfish frequencies may also have an impact on the overall growth rates and maximum size of hellbenders. Growth rates of brown trout ( Salmo trutta ) in Pennsylvania streams correlated with specific conductance, which the authors relate d to the geological characteristics of the studied streams (McFadden and Cooper, 1962). Fish in rivers associated with limestone exhibited higher growth rates than those in sandstone an d shale areas. During this study period fewer large adult hellbenders were present in LR than are typically found in other populations with carbonate rocks like the NFWR. King (1939) reported a large female, 635 mm TL, taken upstream from the current stu dy sites in LR. Although there are no additional data to suggest larger adults were at one time more prevalent, this
` 80 specimen suggests that hellbenders in LR were at least capable of attaining larger sizes historically. N o historical data on crayfish in LR is available to examine if prey populations have changed over time, which could have impacted long term population structure trends. I t remains unclear if large adults are absent because hellbenders do not grow as large in LR due to low prey population s, experience increased mortality due to reduced prey availability, or are missing due to other factors such as flooding events and recruitment. Larval Diet While ontogenetic habitat shifts are common in cannibalistic species, ontogenetic shifts in diet are also common in species ingesting entire food items or those that undergo some form of metamorphosis, such as C. alleganiensis (Giller and Malmqvist, 1998). Knowledge of diet can help elucidate aspects of the general ecology of a species as well as assist in conservation efforts. While a number of diet studies have been completed on C. alleganiensis these samples have come almost entirely from adults (Smit h, 1907; Netting, 1929; Green, 1933; Green, 1935; Bishop, 1941; Nickerson and Mays, 1973; Nickerson et al., 1983, Peterson et al.,1989). Only two previous diet samples from larvae have been published (Smith, 1907; Pitt and Nickerson, 2006). Larval hellbe nders are quite small compared to mature individuals, and therefore a shift in diet due to gape limitation would be expected. Consistent with the findings of Pitt and Nickerson (2006), most diet items collected from larvae in LR were comprised of aquatic insects. In general, the items found within larval hellbender stomach samples were taxa associated with the habitat they were found to be utilizing during the study period. Immature individuals of the order Ephemeroptera, the mayflies, were the most commo n food item identified. The family most commonly identified in the diet samples,
` 81 Heptageniidae, is generally associated with fast moving water. Many species in this family are classified as clingers and are found attached to the underside of submerged ro cks and logs in riffles where many species scrape algae for consumption (Merritt and Cummins, 1996). Representatives of this family were regularly encountered while turning rocks during surveys in LR, and appear to be widely available to larval hellbender s within the safety of their shelter sites. One larva also had eaten two members of the family Baetidae, also commonly found on or under rocks and stones in shallow riffle areas (Merritt and Cummins, 1996). The next most commonly identified order, the cad disflies (Trichoptera), primarily represented one family: Polycentropodidae. Individuals from this family are generally net builders and construct net like structures substrates in moving water to provide refuge from flow and predators, as well as capture food particles caught in the stream rocks in riffle and run areas within LR during the study period. Parts from small juvenile crayfish were the third most common item found in diet samples. Based on observation, these sized crayfish were not typically found in the open areas of riffles and runs of LR but rather along the stream margins or areas protected from stream flow. This trend has been documented in other local ities (Creed, 1994), and crayfish are known to exhibit habitat differences depend ent on size (Flinders, 2007). However, hellbender larvae were observed throughout the width of LR, and were not limited to stream margins. Data regarding the location of hel lbender capture in re ference to the stream bank s were not taken during this survey, so it is
` 82 unclear if larvae that had consumed crayfish were utilizing habitat near shore or if larvae encountered this prey item due to some other reason. Like the mayfly an d caddisfly families identified, the remaining identifiable items in the larval hellbender diet samples are regular inhabitants of benthic substrates in flowing water. The family Perlidae represented the order Plecoptera in the diet samples. Members of t his family are predators commonly found under rocks in streams (Merritt and Cummins, 1996). One representative from the order Coleoptera was found. This adult beetle was identified as a riffle beetle (f amily Elmidae) that true to its name crawl s along the gravel and rocky substrates of stream riffle s (Merritt and Cummins, 1996). Based on observation, larval salamanders of other species, particularly Desmognathus and Eurycea appeared to occasionally utilize habitat similar to that of larval hellbenders, as they were encountered with some regularity during survey efforts. Therefore it wa s not entirely surprising to report a larval Eurycea in a larval hellbender diet sample The size of the vertebrate item in compar ison to its predator, however, wa s surpr ising. The consumption of a 40 mm item by a 50 mm larval C. alleganiensis suggests that hellbender larvae are able to consume a wide size variety of prey items. Previous reports indicate d that a second year hellbender larvae had eaten a smaller conspecif ic (Smith, 1907). While most prey items identified during this study were small, larval hellbenders appear to be efficient predators able to consume relatively large prey. An examination of the ontogeny of dentition in C. alleganiensis by Greven and Cleme n (2009) found that the transformation of teeth in this species took place
` 83 particularly early, especially in reference to the loss of gills. Unlike a 29 mm larva, all teeth present in a 47 m m TL larva were entirely pedice llate and bicuspid, characteristic s associated with maturity in salamanders. This early transformation is unique among caudates, and teeth transformation in C. alleganiensis appears to occur around the time of hind limb maturation rather than gill transformation. Like adults, larvae also lacked vomerine tooth patches, which may be advantageous for swallowing whole fi nd items quickly. This suggested that even young larvae have adapted similar feeding mechanisms as adults, and can thus capture and swallow large prey items with relative ease. The types of organisms found within the stomach samples of larval hellbenders captured in LR shed ligh t on the foraging behavior and general ecology of larvae within LR. Larvae appear ed to be mostly consuming items in or near their shelter sites, an d not actively foraging in the open stream or in the interstitial spaces of the streambed or streambed particles. For a small organism in a stream with a variety of predators such as larger hellbenders, a wide variety of fish, aquatic insects, snakes, ott ers, and birds, actively foraging would presumably be dangerous. Like adults, variation in the diet of larval hellbender, dependent on locality and food availability probably occurs, but aquatic insects appear ed to be regular food items of larvae in gener al. While previous studies found that adult C. alleganiensis do occasionally consume aquatic insects (Green, 1935; Peterson, 1989), there is no indication that they make up a large proportion of their diet. Therefore an ontogenetic shift in diet a ppears likely among hellbenders, at least in LR. This is a significant finding because conservation efforts surrounding the hellbender typically focus primarily on crayfish populations as
` 84 prey However, aquatic insects and their h abitat, may be importan t for the survival and recruitment of young hellbenders, and should be considered in manage ment and conservation actions.
` 85 Figure 4 1 Grouped histogram showing differences in size class distributions of hellbenders ( Cryptobranchus alleganiensis ) captured in Little River, TN from 2000 2010 (n=500) and the North Fork of the White River MO in 1969 (n=478).
` 86 Figure 4 2 Map of the eastern United States showing protected areas in the southern Appalachian and Ozark regions (Modified from Fenneman and Johnson, 1946; U.S. Geological Survey, 2011)
` 87 Figure 4 3 Annual peak streamflow at Little River, TN USGS station within Great Smoky Mountains National Park ( Courtesy of U.S. Geological Survey, 2001).
` 88 CHAPTER 5 CONCLUSIONS This research aimed to investigate the impacts of stream geomorphology on the population structure and ecology of hellbenders within LR. The geologic history of the GSM created a riverbed composed primarily of metamorphosed sandstone, which ap pears to be an important influence in the ecology of C. alleganiensis found within LR. The geomorphology of this stream potentially affected detectability, prey availability, habitat use, and the overall population structure of hellbenders. The size st r ucture of hellbenders in LR was unique compared to most studied localities in its large proportion of young individuals, particularly larvae, as well as the relatively small number of large adults. The increase in larvae may have be en partially due to hig her detectability of hellbenders within LR caused by differences in bedrock geology and habitat use from other sites, allowing larvae to be more accurately sampled Recent eff orts to specifically target potential larval habitat in other rivers have increa sed capture s of young individuals in some sites, but no t n ear the proportion seen in LR. A dult C. alleganiensis populations however, have experienced documented or suspected declines in many other streams (Trauth et al., 1992; Wheeler et al., 2003 ; Briggler et al., 2007; Foster et al. 2009; Nickerson et al., 2009; Burgmeier, 2011b), which could lead to an overall reduction in larval recruitment simply due to fewer reproducing individuals. Although hist oric data is not available for LR, the current ad ult hellbender population appeared stable and healthy. L R began in the confines of GSMNP, and therefore human related issues that could potentially affect reproduction and recruitment in other localities, such as pollution, endocrine dis ruptors, and hab itat alterations were not evident there
` 89 As originally hypothesized by Nickerson et al. (2003), the metamo rphosed sandstone that comprised the be drock of LR appeared to be a particularly important factor affecting the habitat use of larval hel lbenders. A s the bedrock eroded, it eventually broke down into small sand particles which fill ed in the space within gravel beds, making th at habitat, w hich had been associated with larvae in other localities, unavailable to larvae. B edrock erosion also left abundan t rounded cobble and boulders on the stream bottom which larval hellbenders utilize d a s shelter in LR. This habitat wa s very similar to the overall shelter type (boulder), streambed particle size, and water depth utilized by both adult and sub adult hell benders within LR. However, a wide availability of different sized shelter rocks allowed larval hellbenders to access smaller shelters on average than older hellbenders, potentially reducing intra specific competition and cannibalism. A s the habitat type utilized by larvae in LR appeared less secure than that used by larvae in o ther localities, mortality may be higher in young hellbenders due to a potential increase in overall predation risk and susceptibility to flooding, leading to pos sible long term alterat ions in population structure. The bedrock geology of LR may have impacted the hellbender population structure by influencing crayfish populations, the main prey item of adult C. alleganiensis Previous observation by Bouchard (unpub l. data) suggested that rivers with non carbonate bedrock typically exhibited lower crayfish densities. Crayfish relative frequencies in LR were lower in comparison to the HR and NFWR. Hellbenders in LR also showed a significantly lower linear regression slope when comparing trends in body condition between the three rivers suggesting that hellbenders in LR are expected to have the lowest mass at a given total length of the three sites NFWR,
` 90 which is the only stream to have a carbonate rock influence, had the highest crayfish relative frequencies as well as the highest overall hellbender body condition. These trends were less clear in sma ll individuals, which, based on the resul ts of this study, primarily fed on aquatic insect larvae rather than crayfi sh i n LR. It is not clear whether reduction in body condition was detrimental to hellbenders or led to increased mortality in larger a dults. H ellbenders might have also experience d decreased growth at larger sizes due to low prey availability, explaining the smaller number of large adults. This study suggested that the geologic history and geomorphology of the bedrock structure s of C. alleganiensis rivers had an important influence on the general ecology and population structure of this species. Theref ore, it is important to consider the impacts of streambed geomorphology on stream ecology when considering conservation and management of C. alleganiensis T hese findings also contribute towards our knowledge of the general ecology of l arval hellbenders i n the wild, a topic that has been largely overlooked for the past 100 years.
` 91 APPENDIX WENTWORTH PARTICLE SIZE CATEGORIES Category Particle size (mm) Sand <2 Very fine gravel 2 4 Fine gravel 4 8 Medium gravel 8 16 Coarse gravel 16 32 Very coarse gravel 32 64 Small cobble 64 90 Medium cobble 90 128 Large cobble 128 180 Very large cobble 180 256 Small boulder 256 512 Medium boulder 512 1024 Large boulder 1024 2048 Very large boulder 2048 4096
` 92 LIST OF REFERENCES ALEXANDER M. M 1958. The place of aging in wildlife management. American Scientist 46(2):123 137. ALFORD, R. A., AND S. J. RICHARDS. 1999. Global amphibian declines: A problem in applied ecology. Annual Review of Ecology and Systematics 30( 1999):133 165. ANONYMOUS 2011. Endangered and threatened wildlife and plants; Endangered status for the Ozark hellbender salamander. Federal Register 76(194):61956 61978. BALL, B. S. 2001. Habitat use and movements of eastern h ellbenders, Cryptobranchus alleganiensis alleganiensis : A radiotelemetric study. M.S. Thesis, Appalachian State University, Boone, NC. BISHOP, S. C. 1941. The Salamanders of New York. New York State Museum Bulletin, The University of the State of New York, Albany, NY. BLAIS, D. P. 1996. Movement, home range, and other aspects of the biology of the eastern hellbender ( Cryptobranchus alleganiensis alleganiensis ): A radiotelemetric study. M.S. Thesis, State University of New York at Binghamton, Binghamton, NY. BRIGGLER, J., J. UTR UP, C. DAVIDSON, J. HUMPHRIES, J. GROVES T. JOHNSON, J. ETTLING, M. WANNER, K. TRAYLO R HOLZER, D. REED, V. LINDGREN, AND O. BYERS (eds.). 2007. Hellbender Population and Habitat Viability Assessment: Final Report. IUCN/SSC Conservation Breeding Specialist Group, Apple Valley, MN. BRODIE, E. D. J R 1971. Two more toxic salamanders: Ambystoma maculatum and Cryptobranchus alleganiensis Herpetological Review 3(1):8. BURGMEIER, N., T. M. S UTTON, AND R. N. WILLIAMS. 2011a. Spatial ecology of the eastern hellbender ( Cryptobranchus alleganiensis alleganiensis ) in Indiana. Herpetologica 67(2):135 145. BURGMEIER, N., S. D. UNGER, T. M. SUTTON, AND R. N. WILLIAMS. 2011b. Population status of the eastern hellbender ( Cryptobranchus alleganiensis alleganiensis ) in Indiana. Journal of Herpetology 45(2):195 201. BURY, R. B., C. K. D ODD J R ., AND G. M. FELLERS 1980. Conservation of the Amphibia of the United States: a Review. Resource Publicatio n 134, U.S. Fish and Wildlife Service, Washington, D.C..
` 93 COLLEY, S. W., W. H. KEEN, AND R. W. REED. 1989. Effects of adult presence on behavior and microhabitat use of juveniles of a Desmognathine salamander. Copeia 1989(1):1 7. CREED, R. C. J R 1994. Direct and indirect effects of crayfish grazing in a stream community. Ecology 75(7):2091 2103. CROWDER, L. B., D. T CROUSE, S. S. HEPP ELL, AND T. H. MARTIN 1994. Predicting the impact of turtle excluder devices on loggerhead sea turtle popu lations. Ecological Applications 4(3):437 45 DIERENFELD, E. S., K. J. MCGRAW, K. FRITSCHE, J. T. BRIGGLER, AND J. ETTLING. 2009. Nutrient composition of whole crayfish ( Or c onectes and Procambarus species) consumed by hellbenders ( Cryptobranchus allegani ensis ). Herpetological Review 40(3):324 330. DOBSON, F. S., AND M. K. OLI. 2001. The demographic basis of population regulation in Columbian ground squirrels. The American Naturalist 158(3):236 247. DOWNING, R. L 1980. Vital Statistics of Animal Populations. In S. D. Schemnitz (ed ), Wildlife Management Techniques Manual. pp. 247 266. The Wildlife Society, Inc., Bethesda, Maryland. DUELLMAN, W. E., AND L. TRUEB. 1986. Biology of Amphibians. McGraw Hill Book Company, New York, NY. DUNDEE, H. A 1971. Cryptobranchus alleganiensis Catalogue of American Amphibians and Reptiles, SSAR:101.1 101.4. DUNDEE, H. A., AND D. S. DUNDEE. 1965. Observations on the systematics and ecology of Cryptobranchus from the Oza rk Plateaus of Missouri and Arkansas. Copeia 1965(3):369 370. FENNEMAN, N. M. 1917. Physiographic subdivision of the United States. Proceedings of the National Academy of Science 3 (1) :17 22. FENNEMAN, N. M., AND D. W. JOHNSON. 1946. Physical divisions of the United States: U.S. Geological Survey: [cited July 2011]. Available from: http://water.usgs.gov/GIS/metadata/usgswrd/ FITCH, F. W. 1947. A record Cryptobranchus alleganiensis Copeia 1947(3):210. FLINDERS, C. A., AND D. D. MAGOULICK. 2007. Habitat use and selection within Ozark lotic crayfish assemblages: spatial and temporal variation. Journal of Crustacean Biology 27(2):242 254.
` 94 FOSTER, R. L., A. M. MCMILLAN, AND K. J. ROBLEE. 2009. Population status of hellbender salamanders ( Cryptobranchus alleganiensis ) in the Alleghany River Drainage of New York State. Journal of Herpetology 43(4):579 588. FOSTER, S. A., V. B. GARCIA, AND M. Y. TOWN. 1988. Cannibalism as the cause of an ontogenetic shift in habitat use by fry of the threespine stickleback. Oecologia 74(4):577 585. GAO, K., AND N. H. SHUBIN. 2003. Earliest known crown group salamanders. Nature 422 (6930):424 428. GILL ER, P. S., AND B. MALMQVIST. 1998. The Biology of Streams and Rivers. Oxford University Press, Inc., New York, NY. GILLESPIE, G. 2010. Population age structure of the spotted tree frog ( Litoria spenceri ): insights into population declines. Wildlife Res earch 37:19 26. GONYNOR, J. L., M. J YABSLEY, AND J. J. JENSEN. 2011. A prelimin ary survey of Batrachochytrium dendrobatidis exposure in hellbenders from a stream in Georgia, USA. Herpetological Review 42(1):58 59. GREEN, N. B. 1933. Cryptobranchus all eganiensis in West Virginia. Proceedings of the West Virginia Academy of Sciences 7:28 30. GREEN, N. B. 1935. Further notes on the food habits of the water dog, Cryptobranchus alleganiensis Daudin. Proceedings of the West Virginia Academy of Sciences 9:36. GREVEN, H., AND G. CLEMEN. 2009. Early tooth transformation in the paedomorphic Hellbender Cryptobranchus alleganiensis (Daudin, 1803)(Amphibia: Urodela). Vertebrate Zoology 29(1):71 79 GROVES, J. D., AND L. A. WILLIAMS. 2011. In search of the hellbender in North Carolina. CONNECT Magazine, March 2011, American Zoological Association; [cited August 2011]. Available from: http://www.aza.org/Membership/detail.aspx?id=17494 GUIMOND, R. W. 1970. Aerial and aquatic respiration in four species of paedomorphic salamanders: Amphiuma means, Cryptobranchus alleganiensis alleganiensis, Necturus maculosus maculosus, and Siren lacertina PhD Dissertation, University of Rhode Island, Kingston, RI. HAMMERSON, G., AND C. PHILLIPS. 2004. Cryptobranchus alleganiensis IUCN 2011. IUCN Red List of Threatened Species. Version 2011.1; [Cited August 2011]. Available from: http:// www.iucnredlist.org
` 95 HILER, W. R., B. A. WHEELER, AND S. E. TRAUTH. 2005. Abnormalities in the Ozark hellbender ( Cryptobranchus alleganiensis bishopi ) in Arkansas: A comparison between two rivers with a historical perspective. Journal of Arkansas Academy of Science 59:88 94. HILLIS, R. E., AND E. D BELLIS. 1971. Some aspects of the ecology of the hellbender, Cryptobranchus alleganiensis alleganiensis in a Pennsylvania stream. Journal of Herpetology 5(3 4):121 1 26. HUGHES, G. M. 1967. Evolution between air and water. In A. V. S. de Reuch and Ruth Porter (eds.), Ciba Foundation Symposium Development of the Lung. pp. 64 84. Little, Brown, and Co., Boston, MA. HUMPHRIES, W. J. 2005. Cryptobranchus alleganiensis (Hellbender). Displacement by a flood. Herpetological Review 36(4):428. HUMPHRIES, W. J, AND T. K. PAULEY. 2005. Life history of the Hellbender, Cryptobranchus alleganiensis in a West Virginia stream. American Midland Naturalist 154:125 142. HUMPHRIES, W. J., M. SOLIS, C. CARDWELL AND A. SALVETER 2005. Cryptobranchus alleganiensis (Hellbender). Cannibalism. Herpetological Review 36(4):428. HURYN, A. D., AND J. B. WALLACE. 1987. Local geomorphology as a determinant of macrofaunal p roduction in a mountain stream. Ecology 68(6):1932 1942. HWA SEONG, J., AND G. M. WARD. 2007. Life history and secondary production of Glossosoma nigrior Banks (Trichoptera: Glossosomatidae) in two Alabama streams with different geology. Hydrobiologia 575:245 258. KEITZER, S. C. 2007. Habitat preferences of the eastern hellbender in West Virginia. M.S. Thesis, Marshall University, Huntington, WV. KING, W. 1939. A survey of the herpetology of the Great Smoky Mountains National Park. American Midland Naturalist 21(3):531 582. KULP, M. A. 2011. Unpublished public presentation. National Park Service, Great Smoky Mountains National Park, Gatlinburg, TN. LIPS, K. R. 2011. Museum collections: Mining the past to manage the future. Proceedings of the Na tional Academy of Sciences 108(9):9323 9324.
` 96 MADDEN, M., R. WELCH, T. R. JORDAN, AND P. JACKSON. 2004. Digital Vegetation Maps for the Great Smoky Mountains National Park. Final Report to U.S. Department of Interior. National Park Service, Great Smok y Mountains National Park, Gatlinburg, TN, Cooperative Agreement No. 1443 CA 5460 98 019. MAST, M. A., AND J. T. TURK. 1999. Environmental characteristics and water quality of Hydrologic Benchmark Network stations in the Eastern United States, 1963 95: U.S. Geological Survey Circular 1173 A. MAXWELL, N. J. 2009. Baseline survey and habitat analysis of aquatic salamanders in the Pigeon River, North Carolina. M .S. Thesis. University of Tennessee, Knoxville, TN. M C FADDEN J. T., AND E. L. COOPER. 1962. An ecological comparison of six populations of brown trout ( Salmo trutta ). Transactions of the American Fisheries Society 91(1):53 62. MCGRATH, K. E., E. T. H. M. PETERS, J. A. J. BEIJER, AND M. SCHEFFER. 2007. Habitat mediated cann ibalism and microhabitat restriction in the stream invertebrate Gammarus pulex Hydrobiologia 589:155 164. MERRIT, R. W., AND K. W. CUMMINS (eds ). 1996. An Introduction to the Aquatic Insects of North America. 3rd Edition. Kendall/Hunt Publishing Compa ny, Dubuque, Iowa. METTER, E. 1968. The influence of floods on population structure of Ascaphus truei Stejneger. Journal of Herpetology 1(1):105 106. MILLER, B. T., AND J. L. MILLER. 2005. Prevalence of physical abnormalities in eastern hellbender ( C ryptobranchus alleganiensis alleganiensis ) populations of middle Tennessee. Southeastern Naturalist 4(3):513 520. MURDOCH, W. E. 1994. Population regulation in theory and practice. Ecology 75(2):271 287. NAYLOR, B. G. 1981. Cryptobranchid salamanders from the Paleocene and Miocene of Saskatchewan. Copeia 1981(1):76 86. NETTING, M. G. 1929. The food of the hellbender, Cryptobranchus alleganiensis (Daudin). Copeia 1929(170):23 24. NICKERSON, M. A. 1978 Maintaining hellbender salamanders in captivity: The evolution of our knowledge. Proceedings of the American Association of Zoological Parks and Aquariums (1977 1978):396 398.
` 97 NICKERSON, M. A. 1980. Return of captive Ozark hellbenders, Cryptobranchus alleganiensis alleganiensis to site of capture. Copeia 1980(3):536 537. NICKERSON, M. A 2003. Asiatic giant salamanders and hellbenders. In M.H. Hutchins Amphibi a 6. pp. 343 347. Gale Group Inc., Detroit, MI. NICKERSON, M. A., AND J. T. BRIGGLER. 2007. Harvesting as a factor in population decline of a long lived salamander; the Ozark hellbender, Cryptobranchus alleganiensis bishopi Grobman. Applied Herpetology 4 :207 216. NICKERSON, M. A., AND K. L. KRYSKO. 2003. Surveying for hellbender salamanders, Cryptobranchus alleganiensis (Daudin): A review and critique. Applied Herpetology 1:37 44. NICKERSON, M. A., AND C. E. MAYS. 1973. The Hellbenders: North American Giant Salamanders. Milwaukee Public Museum, Milwaukee, WI. NICKERSON, M. A., R. E. ASHTON, AND A. L BRASWELL. 1983. Lampreys in the diet of the hellbender Cryptobranchus alleganiensis (Daudin) and the Neuse River waterdog Necturus lewisi (Brimley). Herpetological Review 14:10. NICKERSON, M. A., K. L. KRYKSO, AND R. D. OWEN. 2002. Ecological status of the Hellbender ( Cryptobranchus alleganiensis ) and the Mudpuppy ( Necturus maculosus ) salamanders in t he Great Smoky Mountains National Park. Journal of the North Carolina Academy of Science 118:27 34. NICKERSON, M. A., K. L. KRYKSO, AND R. D. OWEN. 2003. Habitat differences affecting age class distributions of the Hellbender salamander, Cryptobranch us a lleganie nsis Southeastern Naturalist 2:619 629. NICKERSON, M. A., A. L. PITT, AND M. D. PRYSBY. 2007. The effects of flooding on Hellbender salamander, Cryptobranchus alleganiensis Daudin, 1803, populations. Salamandra 43(2):111 117. NICKERSON, M. A ., A. L. PITT, AND J. T. TAVANO. 2009. Decline of the Ozark hellbender ( Cryptobranchus alleganiensis bishopi ) in the North Fork White River, Ozark County, Missouri: A historical habitat perspective. A final report submitted to the Saint Louis Zoological Park and the Reptile and Amphibian Conservation Corp. Reptile and Amphibian Conservation Corps: Gainesville, FL. NIGRELLI, G. K. 1954. Some longevity records of vertebrates. Transactions of the New York Academy of Science 16(6):296 299. PETERSON, C. L. 1988. Breeding activities of the hellbender in Missouri. Herpetological Review 19:28 29.
` 98 PETERSON, C. L. 1989. Seasonal food habits of Cryptobranchus alleganiensis (Caudata: Cryptobranchidae). The Southwestern Naturalist 34(3):438 441. PETERSON, C. L., R. F. WILKINSON, M. S. TOPPING, AND D. E. METTER. 1983. Age and growth of the Ozark hellbender ( Cryptobranchus alleganiensis bishopi ). Copeia 1983:225 231. PETERSON, C. L., D. E. METTER, B. T. MILLER, R. F. W ILKINSON, AND M. S. TOPPING. 1988. Demography of the hellbender Cryptobranchus alleganiensis in the Ozarks. American Midland Naturalist 119:291 303. PETRANKA, J. W. 1998. Salamanders of the United States and Canada. Smithsonian Institution Press, Wash ington D.C.. PITT, A. L, AND M. A. NICKERSON. 2006. Cryptobranchus alleganiensis (Hellbender salamander). Larval diet. Herpetological Review 37(1):69. POWERS, M. E., R. J. STOUT, C. E. CUSHING, P. P. HARPER, F. R. HAUER, W. J. MATTHEWS, P. B. MOYLE, B. STATZNER, AND I. R. WAIS DE BADGEN. 1998. Biotic and abiotic controls in river and stream communities. Journal of the North American Benthological Society 7(4):456 479. R DEVELOPMENT CORE TEA M 2008 R: A language and environmen t for statistical computing. R Foundation for Statistical Computing, Vienna Austria. Available from: http://www.R project.org RASHLEIGH, B. 2004. Fish assemblage groups in the Upper Tennessee River Basin. South eastern Naturalist 3(4):621 636. RODENHOUSE, N. L., T. W. SHERRY, AND R. T. HOLMES 1997. Site dependent regulation of population size: A new synthesis. Ecology 78(7):2025 2042. SAMAB ( SOUTHERN APPALACHIAN MAN AND THE BIOSPHER E ). 1996a. The Southern Appalachian Assessment Social/Cultural/Economic Technical Report. Report 4 of 5. Atlanta: U.S. Department of Agriculture, Forest Service, Southern Region. SAMAB ( SOUTHERN APPALACHIAN MAN AND THE BIOSPHER E ). 1996b. The Southern Appalachian Asses sment Terrestrial Technical Report. Report 5 of 5. Atlanta: U.S. Department of Agriculture, Forest Service, Southern Region. SEKHON, J. S. 2011. Multivariate and Propensity Score Ma tching Software with Balance Optimization: The Matching Package for R. Jo urnal of Statistical Software 42(7):1 52 SHANKS, R. E. 1954. Climates of the Great Smoky Mountains. Ecology 35(3):354 361.
` 99 SMITH, B. G. 1907. The life history and habits of Cryptobranchus alleganiensis Biological Bulletin 13(1):5 39. SMITH, B. G. 191 2. Embryology of Cryptobranchus alleganiensis including comparisons with some other vertebrates. Journal of Morphology 23(1):61 157. SWANACK, T. M., W. E. GRANT, AND M. R. J. FORSTNER. 2009. Projecting population trends of endangered amphibian species in the face of uncertainty: A pattern oriented approach. Ecological Modelling 220(2009):148 159. SWANSON, F. J. 1980. Geomorphology and Ecosystems. In R. H. Waring (ed)., Forests: Fresh Perspectives from Ecosystem Analysis, pp.159 170 Oregon State University Press, Corvallis, OR. TABER, W. E., R. F. WILKINSON J R ., AND M. S. TOPPING. 1975. Age and growth of hellbenders in the Niangua River, Missouri. Copeia 1975(4):633 639. TOPPING, M. S., AND C. A. INGERSOL. 1981. Fecundity in the hellbender, Cryptobranchus alleganiensis Copeia 1981(4):873 876. TRAUTH, S. E., J. D. WILHIDE, AND P. DANIEL. 1992. Status of the Ozark hellbender, Cryptobranchus bishopi (Urodela: Cryptobranchidae) in the Sprin g River, Fulton County, Arkansas. Proceedings of the Arkansas Academy of Science 46:83 86. TUMLISON, R. AND G. R. CLINE. 2003. Association between the Oklahoma Salamander ( Eurycea tynerensis ) and Ordovician Silurian Strata. The Southwestern Naturalist 48(1):93 95. TUMLISON, R., G. R. CLINE, AND P. ZWANK 1990. Surface habitat associations of the Oklahoma salamander ( Eurycea tynerensis ). Herpetologica 46:169 175. U.S. GEOLOGICAL SURVEY. 2001, National Water Information System Data Available on the World Wide Web (Water Data for the Nation). USGS 03497300 Little River above Townsend, TN; [cited June 2011]. Available from: http://waterdata .usgs.gov/usa/nwis/uv?03497 300 US GEOLOGICAL SURVEY GAP ANALYSIS PROGRAM (GAP). 2011. Protected Areas Database of the United States (PADUS), version 1.2; [cited August 2011]. Available from: http://gapanalysis.usgs.gov/PADUS U.S. GEOLOGICAL SURVEY NATIONAL AMPHIBIAN ATLAS. 2010. Hellbender ( Cryptobranchus alleganiensis ). Version Number 2.1. USGS Patuxent Wildlife Research Center, Laurel, Maryland; [cited August 2011]. Available from: http://www.pwrc.usgs.gov:8080/mapserver/naa/
` 100 VI, J. C., C. HILTON TAYLOR, AND STUART, S.N. ( eds .). 2009. Wildlife in a Changing World An Analysis of the 2008 IUCN Red List of Threatened Species. IUCN, Gland, Switzerland. WENTWORTH C. K. 1922. A s cale of grade and class terms for clastic sediments. Journal of Geology 30:377 392. WERNER E. E. AND J. E. Gilliam. 1984. The ontogenetic niche and species interactions in size structured populations. Annual Review of Ecology and Systematics 15(1984):393 425. WHEELER, B. A., E. PROSEN, A. MATHIS, AND R. F. WILKINSON. 2003. Population declines of a long lived salamander: A 20+ year study of hellbenders, Cryptobranchus alleganiensis Biological Conservation 109(2003):151 156. WIGGS, R. L. 1 977. Movement and homing in the hellbender, Cryptobranchus alleganiensis in the Niangua River, Missouri. M.A. Thesis, Southwest Missouri State, Springfield, MO. WOLMAN, M. G., 1954, A method of sampling coarse river bed material: Transactions of the American Geophysical Union (EOS) 35:951 956.
` 101 BIOGRAPHICAL SKETCH Kirsten Hecht Kardasz was born and raised in northern Ohio, and grew up chasing toads and garter snakes in her back yard. She attended Perkins High School in Sandusky OH while also competitively showing her Appaloosa horses. In 2004 she graduated cum laude, with honors from The Ohio S tate University with a B.S. in evolution and e cology and a mino r in natural resource m anagement. After graduation she had her first e Wheeling, West Virginia. Following her time as a tech for a Virginia Polytechnic Institute study focused on terrestrial salamanders in eastern West Virginia, Kirsten moved to Florida where s he worked on gopher tortoise and flatwoods salamander projects for the Florida Fish and Wildlife Conservation Commission. She was accepted as a student in the Interdisciplinary Ecology program at the University of Florida in 2008 and returned her focus to her favorite species, the hellbender. Her research interests include behavioral ecology, population ecology, and conservation biology of herpetofauna, particularly salamanders. Kirsten and her husband, Paul, currently reside in Gainesville, FL along wit h their 2 year old son, Dmitry. Following graduation, Kirsten plans to continue focusing on conservation issues surrounding amphibians.