Chelydra Serpentina Research Articles

Turning turtle: scaling relationships and self-righting ability in Chelydra serpentina.

Testudines are susceptible to inversion and self-righting using their necks, limbs or both, to generate enough mechanical force to flip over. We investigated how shell morphology, neck length and self-righting biomechanics scale with body mass during ontogeny in Chelydra serpentina, which uses neck-powered self-righting. We found that younger turtles flipped over twice as fast as older individuals. A simple geometric model predicted the relationships of shell shape and self-righting time with body mass. Conversely, neck force, power output and kinetic energy increase with body mass at rates greater than predicted. These findings were correlated with relatively longer necks in younger turtles than would be predicted by geometric similarity. Therefore, younger turtles self-right with lower biomechanical costs than predicted by simple scaling theory. Considering younger turtles are more prone to inverting and their shells offer less protection, faster and less costly self-righting would be advantageous in overcoming the detriments of inversion.

Size Matters: the Influence of Trap and Mesh Size on Turtle Captures

ABSTRACTMethods used in wildlife ecology can influence population‐ and community‐level estimates, such as species richness, sex ratio, age and size structure, occupancy and detection probabilities, and community composition. Various trapping and sampling biases exist for freshwater turtles including bait and trap choice and survey technique. To date, no study has investigated the influence of hoop net and mesh size on various population‐ and community‐level estimates. Here, we use detection models to determine if trap and mesh size influence detection probability of nine species of freshwater turtles over 3 consecutive years (2016–2018) in west Tennessee. Additionally, we use multivariate models to determine if freshwater turtle community composition was influenced by hoop trap and mesh sizes. Our results indicated that there was a bias related to mesh size in detection probabilities and community composition. Smaller mesh sized traps were better at detecting smaller‐bodied turtle species, which then changed community species richness but not catch‐per‐unit‐effort estimates (i.e., abundance). Additionally, larger mesh sized traps were better at detecting common snapping turtles (Chelydra serpentina), which supports previous research. Our results suggest that researchers should account for the variation in detection probabilities by mesh size when conducting mark‐recapture and occupancy analyses. Moreover, erroneous inferences about population trends and changes in diversity within turtle communities through time could cause managers to misidentify population declines and conservation value of a site. © 2021 The Wildlife Society.

Maternal provisioning and fluctuating thermal regimes enhance immune response in a reptile with temperature-dependent sex determination

The Charnov-Bull model of differential fitness is often used to explain the evolution and maintenance of temperature-dependent sex determination (TSD). Most tests of the model focus on morphological proxies of fitness, such as size traits, whereas early life physiological traits that are closely related to lifetime fitness might provide a framework for generalizing the Charnov-Bull model across taxa. One such trait is the strength of the early-life immune response, which is strongly linked to early-life survival and fitness. Here, we manipulated temperature, variance in temperature, and sex to test the Charnov-Bull model using a physiological trait, immune system strength, in the snapping turtle (Chelydra serpentina). We found no evidence of sex-specific differences in bactericidal capacity of hatchling blood, and no evidence that mean temperature influences bactericidal capacity. However, we did find that fluctuating incubation temperature (i.e. a more naturalized incubation regime) is associated with a greater bactericidal capacity compared with constant temperature incubation. We also found that egg mass, a proxy for maternal provisioning, is positively associated with bactericidal capacity. Our findings suggest that the evolution of temperature-dependent sex determination in reptiles is unrelated to our measure of early-life innate immunity. Our study also underlines how immune response is condition dependent in early life, and questions the biological relevance of constant temperature incubation in experimental studies on ectotherm development.

A snapshot of the distribution and demographics of freshwater turtles along Toronto’s Lake Ontario coastal wetlands

The aim of this study was to provide a baseline assessment of the turtle community in the coastal wetlands of the Greater Toronto Area. We documented turtle species diversity, abundance, reproductive classes, sex-ratios, and evidence of inter-wetland movement. Our study consisted of a series of mark-recapture surveys across eleven Lake Ontario coastal wetland complexes of the Greater Toronto Area performed between 2016 and 2019. We captured and marked 532 individual turtles of four native species (298 midland painted, Chrysemys picta marginata; 180 snapping, Chelydra serpentina; 7 Blanding’s, Emydoidea blandingii, and 5 map, Graptemys geographica) and three non-native species (40 red-eared slider, Trachemys scripta elegans; 1 false map, Graptemys pseudogeographica, and 1 Chinese softshell, Pelodiscus sinensis). Of note was the capture of an exceptionally large male snapping turtle, one of the largest recorded in Canada for both length and mass. The age classes of both snapping and midland painted species presented large proportions of breeding-sized adults, yet midland painted turtles showed a potential low recruitment with an underrepresentation of non-reproductive females. The sex ratios of both midland painted and snapping turtles across the whole waterfront did not differ from the expected 1:1 ratio. We also recaptured 198 turtles (135 midland painted, 53 snapping, 6 Blanding’s and 12 red-eared Sliders). The recaptured turtles revealed inter-wetland movements of 12 km over a two-year span for a midland painted turtle and an 8 km journey for a snapping turtle, potentially demonstrating some connectivity between geographically separate wetland complexes.

A model of seasonal variation in somatic growth rates applied to two temperate turtle species

Modeling somatic growth of animals whose growth rates are seasonally variable is a challenge. Seasonal variation in growth reduces model fit and precision if not accounted for, and ad hoc adjustments to growth models may be biased or biologically unrealistic. We developed a growth phenology model (GPM) that uses a logistic function to model the cumulative proportion of total annual growth. We applied this model using two different approaches to datasets from temperate-climate populations of two freshwater turtle species that experience extended winter dormancy during which no growth occurs. The first dataset consisted of repeated intra-annual observations of sub-adult snapping turtles (Chelydra serpentina) tracked by radio telemetry, which we analyzed in a Bayesian context, focusing on growth over a single season. We then demonstrated a post hoc combination of the fitted GPM with a separate overall growth model. For the second application, we fully integrated the GPM into a hierarchical von Bertalanffy growth model, which we applied to a dataset of primarily inter-annual observations of juvenile midland painted turtles (Chrysemys picta marginata). Specifying informative priors allowed us to fit the model despite the sparseness of intra-annual information in the data. We also demonstrate using the beta cumulative distribution function as an alternative to the logistic function in the GPM. We discuss incorporating prior knowledge about seasonal foraging and activity periods into growth models via a GPM as a transparent alternative to deterministic, implicit, a priori constructs.

Climate effects on nesting phenology in Nebraska turtles.

A frequent response of organisms to climate change is altering the timing of reproduction, and advancement of reproductive timing has been a common reaction to warming temperatures in temperate regions. We tested whether this pattern applied to two common North American turtle species over the past three decades in Nebraska, USA. The timing of nesting (either first date or average date) of the Common Snapping Turtle (Chelydra serpentina) was negatively correlated with mean December maximum temperatures of the preceding year and mean May minimum and maximum temperatures in the nesting year and positively correlated with precipitation in July of the previous year. Increased temperatures during the late winter and spring likely permit earlier emergence from hibernation, increased metabolic rates and feeding opportunities, and accelerated vitellogenesis, ovulation, and egg shelling, all of which could drive earlier nesting. However, for the Painted Turtle (Chrysemys picta), the timing of nesting was positively correlated with mean minimum temperatures in September, October, December of the previous year, February of the nesting year, and April precipitation. These results suggest warmer fall, and winter temperature may impose an increased metabolic cost to painted turtles that impedes fall vitellogenesis, and April rains may slow the completion of vitellogenesis through decreased basking opportunities. For both species, nest deposition was highly correlated with body size, and larger females nested earlier in the season. Although average annual ambient temperatures have increased over the last four decades of our overall fieldwork at our study site, spring temperatures have not yet increased, and hence, nesting phenology has not advanced at our site for Chelydra. While Chrysemys exhibited a weak trend toward later nesting, this response was likely due to increased recruitment of smaller females into the population due to nest protection and predator control (Procyon lotor) in the early 2000s. Should climate change result in an increase in spring temperatures, nesting phenology would presumably respond accordingly, conditional on body size variation within these populations.

Demography of Aquatic Turtles (Chrysemys picta marginata and Chelydra serpentina serpentina) in Southwestern Pennsylvania

Multi-year studies of syntopic species provide a spatiotemporal framework for comparing their demographic responses to the same environmental conditions. We used data derived from 15 years of sampling at an artificial pond matrix in southwestern Pennsylvania to investigate the survival, growth, and ages of Midland Painted Turtles (Chrysemys picta marginata) and Common Snapping Turtles (Chelydra serpentina serpentina). We trapped turtles with baited hoop-nets at a primary wetland, which was the largest and deepest of five artificial ponds in a spatially aggregated matrix at the Powdermill Nature Reserve, a protected site in the Allegheny Mountains. We captured 81 Midland Painted Turtles 162 times, and 43 Common Snapping Turtles 136 times. For both species, apparent survival probabilities were higher for adults (range 79–95%) compared to juveniles (range 57–82%), and higher in females compared to males or juveniles. The average growth rate was highest in juvenile turtles of both species, indicating growth was maximal during periods of the lowest survival. Average growth rates, in general, were slower for Midland Painted Turtles compared to Common Snapping Turtles. Relating body size to age revealed estimates conforming to studies elsewhere and to longevity records based on known-age turtles. We interpret findings at this wetland matrix to represent the demographics of a deme within a fluid and dynamic regional network of demes for these two species and highlight the value of artificial pond networks to the conservation of freshwater turtle metapopulations in Pennsylvania.

Ecology of Riverine Turtle Communities in the Southern United States: Food Resource Use and Trophic Niche Dimensions

As part of an integrated study of the ecology of freshwater riverine turtle communities in the southern United States, we analyzed food resource partitioning in the turtle communities of the Cahaba, Chickasawhay, and Pearl rivers. We collected turtles with an array of unbaited fyke nets for periods of 10 d from 1 July to 13 August 1978 and 30 April to 4 August 1979, capturing 2707 turtles of 16 species in 2428 trap days. We successfully flushed the stomach contents from 729 turtles of the following species: Apalone mutica, Apalone spinifera, Graptemys flavimaculata, Graptemys gibbonsi, Graptemys nigrinoda, Graptemys oculifera, Graptemys pearlensis, Graptemys pulchra, Pseudemys concinna, Sternotherus carinatus, Sternotherus peltifer, and Trachemys scripta. We also caught 4 other species in low numbers: Chelydra serpentina, Graptemys pseudogeographica kohnii, Macrochelys temminckii, and Sternotherus odoratus. Stomach contents were identified and quantified by volume and percentage of occurrence for each species from each river. Food items were identified and placed in 6 categories: crustaceans, insects, mollusks, fish, plants, and unidentified. Pseudemys concinna was the most specialized feeder at all 3 sites, feeding almost exclusively on plants, followed by the wide-headed Graptemys and then narrow-headed Graptemys. Specialist species tended to show extensive niche overlap with any other species that consumed a large proportion of the specialists' preferred foods.

Draft Genome of the Common Snapping Turtle, Chelydra serpentina, a Model for Phenotypic Plasticity in Reptiles.

Turtles are iconic reptiles that inhabit a range of ecosystems from oceans to deserts and climates from the tropics to northern temperate regions. Yet, we have little understanding of the genetic adaptations that allow turtles to survive and reproduce in such diverse environments. Common snapping turtles, Chelydra serpentina, are an ideal model species for studying adaptation to climate because they are widely distributed from tropical to northern temperate zones in North America. They are also easy to maintain and breed in captivity and produce large clutch sizes, which makes them amenable to quantitative genetic and molecular genetic studies of traits like temperature-dependent sex determination. We therefore established a captive breeding colony and sequenced DNA from one female using both short and long reads. After trimming and filtering, we had 209.51Gb of Illumina reads, 25.72Gb of PacBio reads, and 21.72 Gb of Nanopore reads. The assembled genome was 2.258 Gb in size and had 13,224 scaffolds with an N50 of 5.59Mb. The longest scaffold was 27.24Mb. BUSCO analysis revealed 97.4% of core vertebrate genes in the genome. We identified 3.27 million SNPs in the reference turtle, which indicates a relatively high level of individual heterozygosity. We assembled the transcriptome using RNA-Seq data and used gene prediction software to produce 22,812 models of protein coding genes. The quality and contiguity of the snapping turtle genome is similar to or better than most published reptile genomes. The genome and genetic variants identified here provide a foundation for future studies of adaptation to climate.

Freshwater turtle by-catch from angling in New Brunswick, Canada

Turtles are among the most threatened vertebrate taxa, with populations especially vulnerable to any increase in adult mortality. By-catch from freshwater angling, as a potential cause of turtle mortality is poorly documented and little understood. Here we document cases of turtle by-catch by recreational anglers in an urban park in New Brunswick and among the wider angling communities in the province. We also consider factors that may influence rates of hooking. Although we are unable to estimate turtle hooking frequency for the provincial recreational angling community as a whole, five of 75 (~7%) anglers interviewed in the urban park reported interactions with a turtle, with most reported incidents (75%) involving hooking. Snapping Turtles (Chelydra serpentina) seem to be more prone to hooking than Eastern Painted Turtles (Chrysemys picta picta). Although we conclude that turtle hooking by recreational anglers appears to be generally uncommon in New Brunswick, even apparently low by-catch rates may be sufficient to lead to population declines at heavily fished sites. The collection of additional data on turtle by-catch in the recreational fishery in Canada is warranted.

N-phenyl-1-naphthylamine (PNA) Accumulates in Snapping Turtle (Chelydra serpentina) Liver Activating the Detoxification Pathway

Substituted phenylamine antioxidants (SPAs) are used in Canadian industrial processes. SPAs, specifically N-phenyl-1-naphthylamine (PNA), have received very little attention despite their current use in Canada and their expected aquatic and environmental releases. There is a research gap regarding the effects of PNA in wildlife; therefore, Chelydra serpentina (common snapping turtle) was studied due to its importance as an environmental indicator species. A chronic experiment was performed using PNA spiked food (0 to 3446 ng/g) to determine its toxicity to juvenile C. serpentina. A significant increase in cyp1a mRNA level was observed in the liver of turtles exposed to 3446 ng/g PNA, suggesting that phase I detoxification is activated in the exposed animals. Additionally, a significant decrease in cyp2b transcript level was observed at the two lowest PNA doses, likely indicating another metabolic alteration for PNA. This study helped determine the molecular effects associated with a PNA exposure in reptiles.

ANALYSIS OF FATTY ACID PROFILES FOR EASTERN BOX (TERRAPENE CAROLINA CAROLINA) AND COMMON SNAPPING (CHELYDRA SERPENTINE) TURTLES IN WILD AND MANAGED CARE ENVIRONMENTS

The housing of wild animals in managed care facilities requires attention to all aspects of husbandry. Diets of wild animals often differ in composition, consistency, and quantity when compared with those in managed care settings including zoos, rehabilitation facilities, and aquaria. It was hypothesized that dietary differences from wild versus managed care would be reflected in data of circulating fatty acids based on previous studies. The current study examined the effect of species and environment on fatty acid concentrations in two omnivorous species of chelonians: Eastern box turtles, Terrapene carolina carolina, and common snapping turtles, Chelydra serpentina, located in the wild and managed care. Whole blood was collected and placed on spot cards for analysis of 26 fatty acids in a total lipid fatty acid profile. The present research indicated that Eastern box turtles have significantly (P < 0.05) higher percentages of linoleic acid (18:2n6), eicosadienoic acid (20:2n6), and mead acid (20:3n9). Common snapping turtles have significantly (P < 0.05) higher percentages of myristic acid (14:0), dihomo-γ-linolenic acid (20:3n6), erucic acid (22:1n9), and n-6 docosapentaenoic acid (22:5n6). Environmental effects also were noted; wild turtles had higher percentages of α-linolenic acid (18:3n3), arachidic acid (20:0), eicosadienoic acid (20:2n6), and eicosatrienoic acid (20:3n3) (P < 0.05), whereas n-6 docosapentaenoic acid (22:5n6) was higher for the managed care group. Eicosadienoic acid (20:2n6), behenic acid; 22:0), adrenic acid (22:4n6), n-6 docosapentaenoic acid (22:5n6), and nervonic acid (24:1) were significantly different (P < 0.05) in species-environment interactions without any noted species or environment patterns. Fatty acids are useful for many important biological functions including proper immune system regulation, and therefore, the present research provides medically relevant data for reptile diagnostics. This research may help further improve diets of all chelonians kept in managed care, regardless of species.

Hatchling turtles ingest natural and artificial incubation substrates at high frequency

Geophagy is the consumption of hard objects with no caloric value (e.g. soil, sand, sediment) called gastroliths. This behaviour is widespread in animals, and among reptiles, geophagy has been reported in crocodilians and lizards and occasionally in chelonians. In this study, we calculated geophagy rates in snapping turtle (Chelydra serpentina) and painted turtle (Chrysemys picta) hatchlings under various incubation protocols, ranging from highly artificial to semi-natural conditions. Among multiple experiments where eggs were incubated atop the nesting substrate, 66% of painted turtle and 58–93% of snapping turtle hatchlings exhibited geophagy within 24 h of hatching. Snapping turtle hatchlings that experienced a simulated natural nest emergence had an 85–100% rate of gastrolith consumption. Hatchling snapping turtles from shallow simulated nests emerged earlier and had higher rates of geophagy compared with those from deeper nests. Given the high frequency, short time period (24~72 h) and variety of incubation protocols under which geophagy occurred, we suggest that this behaviour is intentional. We discuss multiple hypothesis for the adaptive and functional significance of geophagic behaviour with respect to chelonians, synthesize existing literature on chelonian geophagy and highlight the possible implications of hatchling turtle geophagy for ex situ captive breeding and head-starting programs. Given that hatchlings readily consume their incubation medium, caretakers should carefully consider the substrate their animals are exposed to. Future research should address how widespread geophagy is among hatchling turtles and the possible role of this behaviour for hatchling ecology and health, including effects on the gut microbiome. Animals regularly consume non-caloric foods, such as rocks and soils. This behaviour is exhibited by hatchling turtles, but why? Our literature review suggests that the ingestion of non-caloric foods by turtles is important for nutrition and, in particular, this behaviour may help establish gut health in hatchlings. Observational and experimental study demonstrated that nest characteristics in-part account for why hatchling ‘turtles eat dirt’. This has applications for hatchling ecology as well as captive rearing conservation programs, an increasingly common strategy for the conservation of these globally imperilled animals. This work complements several recent studies and review articles about geophagy in other major vertebrate groups (birds, mammals) and provides a comprehensive summary on the current state of knowledge of this behaviour for turtles.

Body size of ectotherms constrains thermal requirements for reproductive activity in seasonal environments

Body size may influence ectotherm behaviour by influencing heating and cooling rates, thereby constraining the time of day that some individuals can be active. The time of day at which turtles nest, for instance, is hypothesized to vary with body size at both inter- and intra-specific levels because large individuals have greater thermal inertia, retaining preferred body temperatures for a longer period of time. We use decades of data on thousands of individual nests from Algonquin Park, Ontario, Canada, to explore how body size is associated with nesting behaviour in Painted Turtles (Chrysemys picta (Schneider, 1783); small bodied) and Snapping Turtles (Chelydra serpentina (Linnaeus, 1758); large bodied). We found that (i) between species, Painted Turtles nest earlier in the evening and at higher mean temperatures than Snapping Turtles, and (ii) within species, relatively large individuals of both species nest at cooler temperatures and that relatively larger Painted Turtles nest later in the evening compared with smaller Painted Turtles. Our data support the thermal inertia hypothesis and may help explain why turtles in general exhibit geographic clines in body size: northern environments experience more daily variation in temperature, and larger size may evolve, in part, for retention of preferred body temperature during terrestrial forays.

Bioaccumulation and physiological responses of the turtle Chelydra serpentina exposed to polychlorinated biphenyls during early life stages

Despite the North American production ban of polychlorinated biphenyls (PCBs), PCBs are ubiquitous in the environment and in wildlife tissues. Chelydra serpentina serpentina (common snapping turtle) have been used as environmental indicators of PCB pollution upwards of 40 years given their high site fidelity and high trophic position. Despite their long use as indicators of PCB contamination, the effects of PCBs in reptiles remain largely unknown. In this study, we performed two experiments to assess i) bioaccumulation and ii) toxicity of PCBs to 1-month-old C. s. serpentina, to aid in interpretation of PCB burdens. Food pellets were spiked at an environmentally relevant concentration (0.45 μg/g) of the PCB mixture Aroclor 1254 to model hepatic bioaccumulation and depuration, through feeding, for 31 days and clean food for 50 days, respectively. No significant differences in PCB concentrations were observed in liver tissue over the course of the experiment, suggesting that juvenile turtles can likely metabolize low environmentally occurring concentrations of PCBs. Additionally, a dose-response experiment, performed to determine hepatic toxicity and bioaccumulation in juvenile C. s. serpentina, showed a 1.8-fold increase in hepatic expression of cyp1a when fed A1254-spiked pellets (12.7 μg/g; range 0–12.7 μg/g). This gene induction correlates with the significant increase of group 3 PCB congeners measured in the turtle liver, which are known to be metabolized by CYP1A. This study indicates that C. s. serpentina may be a good environmental indicator for PCBs, while more research is needed to assess the effects of body burdens in wild C. s. serpentina.

Wait and snap: eastern snapping turtles (Chelydra serpentina) prey on migratory fish at road-stream crossing culverts.

There is growing evidence that culverts at road-stream crossings can increase fish density by reducing stream width and fish movement rates, making these passageways ideal predator ambush locations. In this study, we used a combination of videography and δ13C stable isotope analyses to investigate predator-prey interactions at a road-stream crossing culvert. Eastern snapping turtles (Chelydra serpentina) were found to regularly reside within the culvert to ambush migratory river herring (Alosa spp.). Resident fish species displayed avoidance of the snapping turtles, resulting in zero attempted attacks on these fish. In contrast, river herring did not display avoidance and were attacked by a snapping turtle on 79% of approaches with a 15% capture rate. Stable isotope analyses identified an apparent shift in turtle diet to consumption of river herring in turtles from culvert sites that was not observed in individuals from non-culvert sites. These findings suggest that anthropogenic barriers like culverts that are designed to allow passage may create predation opportunities by serving as a bottleneck to resident and migrant fish movement.

Passive transport of Eastern Elliptio (&lt;i&gt;Elliptio complanata&lt;/i&gt;) by freshwater turtles in New England

Dispersal of freshwater mussels (order Unionida) is primarily as glochidia on the fins and gills of host fish. Adult mussels are more sessile, generally moving short distances (&lt;2 m/week) along lake and river beds. Between 2007 and 2016, we observed seven instances of adult Eastern Elliptio (Elliptio complanata) and one instance of a fingernail clam (Sphaerium sp.) attached to the feet of freshwater turtles in streams and ponds of New England, United States. Observations included five instances of mussels attached to Wood Turtles (Glyptemys insculpta) in Maine and Massachusetts, one instance of a mussel attached to the fingernail of an Eastern Painted Turtle (Chrysemys picta) in Massachusetts, one instance of a mussel attached to a Snapping Turtle (Chelydra serpentina) in Massachusetts, and one instance of a fingernail clam attached to the fingernail of an Eastern Painted Turtle in Massachusetts. We suggest that Eastern Elliptio may be susceptible to transport by freshwater turtles foraging in mussel beds and that transport of adult mussels by freshwater turtles could result in otherwise atypical long-distance, upstream, or overland dispersal between waterbodies.

Spatial and Thermal Ecology of Snapping Turtles (Chelydra serpentina) in a Small, Dystrophic Lake in Central Michigan

Understanding the interface between spatial and thermal ecology is integral to understanding energy acquisition and the life histories of ectotherms. Snapping turtles (Chelydra serpentina) occupy a wide range of habitats that vary greatly in their thermal properties. We studied activity, movements, and thermoregulation of C. serpentina in a small, land-locked lake in central Michigan, USA, using radiotelemetry. Consistent with our a priori predictions, turtles were active within core areas along the lake's edge, showed both diurnal and nocturnal activity, and did not make extensive interwetland movements. Turtles left the lake only for nesting or to hibernate in Sphagnum peat or in the banks of a nearby stream. Home range and core area size estimates of C. serpentina were small compared with other previously studied populations, perhaps in part because of the small dimensions of our lake. Contrary to our prediction of a broad Tset (thermoregulatory set-point) range for a large-bodied, habitat generalist turtle, we found a comparatively low and narrow laboratory-determined Tset range (22°C–26°C). Turtle body temperatures (Tb) cycled between May and August and attained maximal values during the evening hours, a pattern that likely results from thermal inertia, the selection of aquatic thermal patches, or both, as Te (operative temperatures) declined. Turtles most effectively maintained Tb within Tset during July and August when thermal conditions were most favorable. Throughout most of the active season the highly aquatic habits of C. serpentina apparently negated the effects of variations in daily weather conditions and their effects on incoming levels of solar radiation on variation in Tb. However, turtles maintained higher average Tb on sunny days compared with overcast days in April and May, the coolest months of the study. Diel Tb cycling ceased during September and October and average Tb declined despite favorable thermal conditions, at least during September, a pattern that could reflect a downward shift in the Tset range. Comparatively, C. serpentina is less effective at thermoregulating than is a small-bodied species at a similar latitude (Chrysemys picta marginata). Apparently, thermal inertia and lack of atmospheric basking proclivities influenced the thermoregulatory precision in our turtles.

Current Distribution and Status of Non-Native Freshwater Turtles in the Wild, Republic of Korea

Globally, an increase in the transportation and expansion of the pet market is the most important cause of the invasion of non-native species. Invasion of non-native species disturbs native ecosystems and leads to socio-economic problems. The pet trade involving turtles has been globally recognized as the route through which non-native species enter ecosystems. As a result, the invasion of non-native turtles worldwide is causing problems such as competition, predation, transmission of parasites, and hybridization with native turtles. Every year, both the number of non-native turtles imported as pets in the Republic of Korea and the number of introduced species found in the wild is increasing. However, the current status of non-native turtles in the wild is not well known, posing major challenges to their management. In this study, we aimed to determine the current status of non-native turtles introduced into the wild in Korea. We analyzed the factors associated with the detection and distribution of non-native turtles. In total, 1587 of non-native turtles (three families, six genera, and 13 species including subspecies) were found in 648 sites in Korea: Chelydra serpentina, Mauremys sinensis, Chrysemys picta bellii, Graptemys ouachitensis, G. pseudogeographica pseudogeographica, G. p. kohni, Pseudemys concinna, P. nelsoni, P. peninsularis, P. rubriventris, Trachemys scripta elegans, T. s. scripta, and T. s. troostii. There was relationship between the distribution of non-native turtles and environmental factors such as precipitation and temperature. Moreover, human factors such as number of human populations and size of region were significantly related with the distribution and number of non-native turtles. In conclusion, it is likely that human factors are associated with the influx of invasive turtles to the natural habitat, while the possibility of survival and adaption for the turtles is associated mainly with environmental factors. Our result will be an essential guideline not only for understanding the current status of non-native turtles in Korea, but also for establishing strategies for management and control.

SHORT TERM MICROBIAL COLONIZATION OF REPTILE ROADKILL

Little is known about how microbes such as bacteria and fungi in the environment tempo­rally colonize common roadkill reptile carcasses (turtles and snakes). We opportunistically collected and deployed a variety of reptile carcasses often found deceased near roads, including an Eastern Ratsnake (Pantherophis alleghaniensis), an Eastern Box Turtle (Terrapene carolina), and a Snapping Turtle (Chelydra serpentina). We sampled bacteria communities of these carcasses daily for five con­secutive days. We enumerated the number of colony-forming units (CFUs) and characterized microbial distinct colonies using morphology and identification of dominant colonies using 16S rRNA sequencing across carcasses. Several ecologically relevant bacterial phyla were successfully identified colonizing and dominating carcasses differentially, including members of Actinobacteria, Firmicutes, and Proteo­bacteria. We observed higher bacterial colonization (CFUs) for both terrestrial and aquatic turtles, T. carolina and C. serpentina, compared to P. alleghaniensis. This study provides baseline data on the temporal microbiology of deceased reptiles found on roads in the piedmont of North Carolina.