Red-bellied Turtle Research Articles

Spatial Capture–Recapture Derived Turtle Capture Probabilities and Densities in the Chesapeake and Ohio Canal

More than half of turtle species worldwide are threatened because of habitat loss, invasive species, environmental pollution, disease, unsustainable use, and global climate change. However, some turtles are capable of existing in highly modified habitats, including structures designed to benefit human populations such as reservoirs and canal systems. Examining turtle distributions in large canal systems can inform conservation plans protecting turtle populations within a potential reservoir network and expand our understanding of underlying mechanisms regulating populations. We conducted spatial capture–recapture on turtles inhabiting sections of the Chesapeake and Ohio Canal. We developed a Bayesian spatial capture–recapture model to estimate densities, sex ratios, and associated capture probability parameters for Chrysemys picta (Painted Turtle), Chelydra serpentina (Common Snapping Turtle), Sternotherus odoratus (Eastern Musk Turtle), and Pseudemys rubriventris (Red-Bellied Turtle) captured at 12 sites along 28 km of the canal. We examined the impact of canal depth and forest cover on population densities and the variation in capture probability between sites and sampling days. We found population densities to vary between sites and the associated sex ratios to vary between species, as did the effect of depth and forest cover. Overall capture rates decreased each day, but there was trap-happy behavior from all species except S. odoratus. Our information can set a baseline for understanding turtle populations and inform management in the Chesapeake and Ohio Canal National Historical Park. It is also one of the first studies to establish methods for using new spatial capture–recapture to quantify densities and aquatic space use of turtles.

Hybridization and low genetic diversity in the endangered Alabama red-bellied turtle (Pseudemys alabamensis).

Pseudemys alabamensis is one of the most endangered freshwater turtle species in the United States due to its restricted geographic distribution in coastal Alabama and Mississippi. Populations of P. alabamensis are geographically isolated from one another by land and saltwater, which could act as barriers to gene flow. It is currently unknown how differentiated these populations are from one another and whether they have experienced reductions in population size. Previous work found morphological differences between Alabama and Mississippi populations, suggesting that they may be evolutionarily distinct. Other Pseudemys turtles such as P. concinna and P. floridana occur naturally within the same geographic area as P. alabamensis and are known to hybridize with each other. These more abundant species could threaten the unique genetic identity of P. alabamensis through introgression. In order to evaluate the endangered status of P. alabamensis and the level of hybridization with other species, we used mitochondrial and nuclear microsatellite markers to assess genetic variation within and among populations of P. alabamensis throughout its range and estimate admixture with co‐occurring Pseudemys species. In P. alabamensis, we found no variation in mitochondrial DNA and an excess of homozygosity in microsatellite data. Our results show genetic differentiation between Alabama and Mississippi populations of P. alabamensis, and low estimated breeding sizes and signs of inbreeding for two populations (Fowl River, Alabama and Biloxi, Mississippi). We also found evidence of admixture between P. alabamensis and P. concinna/P. floridana. Based on our results, P. alabamensis is highly endangered throughout its range and threatened by both low population sizes and hybridization. In order to improve the species’ chances of survival, focus should be placed on habitat preservation, maintenance of genetic diversity within both the Mississippi and Alabama populations, and routine population‐monitoring activities such as nest surveillance and estimates of recruitment.

Relationship between Plastron Color and Nutrition in Pseudemys nelsoni Carr, 1938

Body coloration of emydids can be triggered by different types of factors. Therefore, the current study aimed to investigate the changes in plastron color of Florida Red-bellied Turtle Pseudemys nelsoni (P. nelsoni Carr, 1938), an emydid of North America. In the current study, 15 (3 males and 12 females) fresh corpses of captive-reared adult specimens of P. nelsoni were analyzed using digital images as well as applying geometric morphometrics and color photo processing techniques. Plastron color had no relationship with size nor fluctuating asymmetry, which could be considered as a negative proxy for stress. Moreover, there were no significant differences between males and females in this regard. It can be suggested that reddish on plastron for P. nelsoni was highly related to feeding, compared to other external factors, such as age, size, or stress. In wild P. nelsoni populations, reddish plastral coloration was related to body size probably due to ontogenetic differences in the diet, as juveniles are omnivorous. Since adults are herbivores, reddish fading observed in the samples of the current study would be a mere expression of unnatural colors, which can probably be linked to unbalanced feeding. The results of the current research could contribute to the understanding of the ways color changes appear in captive turtles in response to differences in dietary access to carotenoids.

Juvenile invasive red-eared slider turtles negatively impact the growth of native turtles: Implications for global freshwater turtle populations

Invasive species are a significant cause of biodiversity declines on a global scale with novel species interactions often causing ecological damage through predation or competition. Red-eared slider turtles (Trachemys scripta elegans) have been introduced to wetlands throughout the world and have negatively impacted native species, particularly other species of turtles. In our controlled feeding experiments in mesocosms juvenile red-eared slider turtles negatively impacted the growth of juvenile red-bellied turtles (Pseudemys rubriventris), an IUCN near threatened species and a Pennsylvania threatened species, through exploitative competition for limited food. In mixed species experimental treatments, in which food resources were abundant, juvenile red-bellied turtles grew significantly faster and ate more food than juvenile red-eared slider turtles. In mixed species experimental treatments, in which food resources were limited, red-eared slider turtles ingested more food, gained mass faster, and maintained body condition while red-bellied turtles lost body condition. There were significant differences in growth rates seen between resource availability regimes. In treatments in which resources were abundant there were no significant differences between turtles housed in mixed species or single species groups. In limited resource treatments red-bellied turtle body condition was significantly different between single and mixed species groups while there were significant differences in mass and body condition for red-eared slider turtles. Our results suggest that one mechanism by which red-eared slider turtles detrimentally impact ecologically similar species is through competition for limited food resources. We hypothesize that growth of red-eared slider turtle populations will lead to population declines of native turtle species throughout their introduced ranges because they use limited food resources more efficiently for their growth and development than native species.

Oviductal eggs from road-kill turtles provide a novel source of DNA for population studies of the Alabama red-bellied turtle

Genetic analyses of the endangered Alabama red-bellied turtle (Pseudemys alabamensis) have the potential to answer questions regarding the species’ population dynamics and reproductive ecology. Here we used oviductal eggs from road-kill female turtles to obtain DNA from P. alabamensis specimens. Six microsatellite markers were successfully amplified in egg yolks/developing embryos. DNA taken from multiple eggs in the same clutch showed variation in allele sizes at multiple loci, indicating amplification of both maternally and paternally contributed alleles. These results introduce DNA extraction from oviductal eggs from road-kill mortalities as a novel approach for examining the reproductive habits and population dynamics of P. alabamensis and similar turtle species. This approach may be particularly effective in exploring mating patterns and monitoring population stability in endangered species where traditional sampling methods are difficult to perform.

Genetic monitoring reveals loss of microsatellite diversity in a breeding population of the endangered Alabama red-bellied turtle

Genetic monitoring is becoming an increasingly effective tool for determining popu- lation stability in endangered species. Evaluating trends in genetic diversity allows conservation managers to identify serious declines and possible extinction risks for threatened populations. Here we used microsatellite analyses to assess the stability of one of the largest known breeding populations of the endangered Alabama red-bellied turtle Pseudemys alabamensis. A total of 238 hatchling specimens were collected over a 9 yr period and analyzed using 6 microsatellite loci. We found no indication of genetic structure within the sample group, indicating that these specimens represent the reproductive output of a single turtle population over 9 consecutive breeding sea- sons. Measures of genetic diversity, including FST values, expected heterozygosity, allelic rich- ness, private allelic richness, and level of inbreeding, were calculated in order to assess the stabil- ity of the population over the 9 yr study period. We detected the impacts of genetic drift within the population as a significant change in allele frequencies (FST) over the study period. We also observed a significant level of inbreeding within this population. We estimated the average effec- tive number of breeders over the study period as Nb = 25, indicating a low number of mature adults contributing to reproductive output each year. Results signal a possible decline in popula- tion numbers of Alabama red-bellied turtles and may be critical in assessing current and future conservation measures for this endangered species.

Stable Isotopes of C and N Reveal Habitat Dependent Dietary Overlap between Native and Introduced Turtles Pseudemys rubriventris and Trachemys scripta

Habitat degradation and species introductions are two of the leading causes of species declines on a global scale. Invasive species negatively impact native species through predation and competition for limited resources. The impacts of invasive species may be increased in habitats where habitat degradation is higher due to reductions of prey abundance and distribution. Using stable isotope analyses and extensive measurements of resource availability we determined how resource availability impacts the long term carbon and nitrogen assimilation of the invasive red-eared slider turtle (Trachemys scripta elegans) and a native, threatened species, the red-bellied turtle (Pseudemys rubriventris) at two different freshwater wetland complexes in Pennsylvania, USA. At a larger wetland complex with greater vegetative species richness and diversity, our stable isotope analyses showed dietary niche partitioning between species, whereas analyses from a smaller wetland complex with lower vegetative species richness and diversity showed significant dietary niche overlap. Determining the potential for competition between these two turtle species is important to understanding the ecological impacts of red-eared slider turtles in wetland habitats. In smaller wetlands with increased potential for competition between native turtles and invasive red-eared slider turtles we expect that when shared resources become limited, red-eared slider turtles will negatively impact native turtle species leading to long term population declines. Protection of intact wetland complexes and the reduction of introduced species populations are paramount to preserving populations of native species.

Tumoral Calcinosis Form of Hydroxyapatite Deposition Disease in Related Red-Bellied Short-Necked Turtles, Emydura subglobosa

Ten of 12 red-bellied short-necked turtles from a single clutch presented at 9 months of age with multiple white to tan nodules on their feet. Histologically, the nodules were composed of large periarticular deposits of mineralized crystalline material that extended into the joint spaces of interphalangeal joints and was surrounded by granulomatous inflammation and fibrosis. Crystallographic analysis determined the material to be apatite (calcium phosphate hydroxide) consistent with the tumoral calcinosis form of hydroxyapatite deposition disease (HADD). HADD has previously been described in aquatic turtles and rarely lizards and must be differentiated from gout in reptiles. A cause for the tumoral calcinosis lesions in these turtles could not be determined; however, based on previous reports in this species, a species-specific predilection, in conjunction with unknown environmental factors, is suspected. The use of the terms HADD, pseudogout (calcium pyrophosphate crystal deposition disease), and calcinosis circumscripta has been inconsistent, creating confusion in the literature.

Characterization of eight polymorphic microsatellite loci for the endangered Alabama red-bellied turtle (Pseudemys alabamensis; Emydidae)

The federally endangered Alabama red-bellied turtle (ARBT; Pseudemys alabamensis) occurs in an isolated range in southern Alabama and Mississippi. Several distinct nesting populations of ARBT exist within this range. Here we identify eight microsatellite markers to be used for a genetic comparison of members of these populations. Previously isolated microsatellite loci in the related species Pseudemys floridana amplified cleanly from DNA extracted from ARBT tissue samples. Alleles at all eight loci were polymorphic. Alleles ranged in size from 136 to 295 base pairs in length. The total number of alleles at each locus ranged from 2 to 11. Loci showed no evidence of linkage disequilibrium or variation from Hardy–Weinberg equilibrium. Observed and expected heterozygosities ranged from 0.13 to 0.88 and 0.12 to 0.84 respectively. Some variation in alleles was observed among members of different nesting populations suggesting that these eight loci will be an important tool in further assessing population structure of Pseudemys alabamensis.

Harderian gland adenocarcinoma in a Florida Red-bellied Turtle ( Pseudemys Nelsoni ) — Case report

The authors describe a case of unilateral adenocarcinoma emerging from the Harderian gland, filling the right orbital cavity of a Florida Red-bellied Turtle ( Pseudemys nelsoni ). The tumour did not produce any metastasis but presented an expansive growth and led to the dislocation and protrusion of the right eyeball. Histopathological analysis revealed the presence of numerous mitotic figures in the cellular population that made up the tumour. The tumour cells completely filled the alveoli of the gland and had a nest-like structure. The authors also emphasise the importance of the differential diagnosis of this rare pathological change in turtles. Epithelial hyperplasia of the Harderian gland's duct, observed in animals suffering from vitamin A deficiency, can also lead to an enlargement of the eyelid, but in these cases the change usually involves both eyelids symmetrically. This is the first description of a Harderian gland adenocarcinoma in a Florida Red-bellied Turtle.

Importance of Development of Ecotoxicogenomics in Understanding Molecular Mechanisms of Chemicals in Developing Animals

Developing organisms are sensitive to estrogenic chemicals. Exposure to estrogens or estrogenic chemicals during critical periods of development induces persistent changes in reproductive as well as nonreproductive organs, including persistent molecular alterations. Chemicals released into the environment potentially disrupt the endocrine system in wild animals and humans, some of which exhibit estrogenic or anti-androgenic activity by binding to estrogen or androgen receptors. Estrogen-responsive genes and critical developmental windows of various animal species, therefore, should be identified to understand the molecular basis of estrogenic activity during embryonic development. To understand molecular mechanisms of estrogenic chemicals in developing organisms, we identified estrogen-responsive genes using cDNA microarrays and a quantitative reverse transcriptase-polymerase chain reaction, and genes related to estrogen-independent vaginal changes in mice induced by estrogens during a critical window. We also analyzed genes in Xenopus laevis embryos related to abnormalities induced by estrogenic chemicals using cDNA microarrays. Estrogen receptors and other steroid hormone receptors were cloned in various species, including the American alligator, crocodile, Florida red-bellied turtle, Silurana tropicalis, roach, Fundulus and mosquito fish. An environmental androgen, trenbolone, was found to induce persistent changes in the gonopodium and ovotestis in mosquito fish. In Daphnia magna, juvenile hormone agonists induce the production of male offspring. Tributyltin (TBT) induces imposex in rockshell through retinoid X receptor (RXR) activation. Microarray technology is a powerful tool for understanding the molecular mechanism of receptor-mediated toxicology in various animal species. Ecotoxicogenomics is a multidisciplinary field concerned with elucidating how the entire genome is involved in the biological response of wild animals exposed to environmental toxicants and stressors. Ecotoxicogenomics combines information from studies of genomic-scale mRNA profiling by microarray analysis (transcriptomics), protein profiling (proteomics), metabolite profiling (metabolonomics) and computational models to understand the roles of gene-environment interaction in the chemical toxicity. To understand the molecular mechanism of chemicals in developing wildlife, the establishment of ecotoxicogenomics is essential in the near future.

A New Species of Neoechinorhynchus (Acanthocephala: Neoechinorhynchidae) from Turtles in Florida, U.S.A.

Neoechinorhynchus moleri n. sp. is described from a yellow-bellied slider (Trachemys scripta scripta) and a Florida red-bellied turtle (Pseudemys nelsoni) from the state of Florida, U.S.A. The new species is distinguished from others in the genus by the shape of the posterior end of the female and by the size, shape, and membrane structure of the egg. The egg of the new species has features similar to both the eggs of Neoechinorhynchus chelonos (lomentiform or “peanut shaped”) and Neoechinorhynchus pseudemydis (with radiating rod-like inclusions). The egg of the new species is smaller than the egg of either N. chelonos or N. pseudemydis, and the rod-like inclusions are restricted to the poles, whereas in N. pseudemydis they are distributed uniformly around the acanthor. Furthermore, the posterior end of the female lacks a large digitiform process such as in N. chelonos. Neoechinorhynchus moleri n. sp. is the second species of Neoechinorhynchus infecting turtles described from peninsular Florida.

Survival and behavior of freshwater turtles after rehabilitation from an oil spill

An oil spill in February 2000 at the John Heinz National Wildlife Refuge in southeastern Pennsylvania affected four species of freshwater turtles including painted turtles (Chrysemys picta), snapping turtles (Chelydra serpentina), red-eared slider turtles (Trachemys scripta), and red-bellied turtles (Pseudemys rubriventris). In the summer and fall of 2000, there were no differences in survival, home range, and temperature preference of 16 oil exposed/rehabilitated (OER) turtles, 18 possibly exposed (PE) turtles, and 32 non-exposed (NE) turtles as measured with temperature sensitive radio transmitters. Post-release mortality or transmitter loss was not correlated to oil exposure (OER=25%, PE=22%, NE=31%). There were no statistically significant differences in home range minimum convex polygon area, (0.28<P <0.87) and water temperature preference (0.35<P <0.99) between OER, PE, and NE male and female C. picta, C. serpentina, and T. scripta. Mean home ranges scaled from 5.0 ha ±4.1 (male C. serpentina ) to 25.5 ha ±5.0 (male P. rubriventris) and mean water temperatures occupied varied from 19.6 °C±6.9 (female C. serpentina) to 22.3 °C±8.5 (female C. picta). Rehabilitation of oil exposed freshwater turtles is effective in restoring these animals to normal behavior in nature.

Temperature Selection by Hatchling and Yearling Florida Red-Bellied Turtles (Pseudemys nelsoni) in Thermal Gradients

Temperature Selection by Hatchling and Yearling Florida Red-Bellied Turtles (Pseudemys nelsoni) in Thermal Gradients

Home Range of the Florida Red-Bellied Turtle (Pseudemys nelsoni) in a Florida Spring Run

The home range of the Florida red-bellied turtle, Pseudemys nelsoni, in a Florida spring run is described using both maximum distance over water and Ford and Krumme's (1979) technique for producing a home range. Ford and Krumme's (1979) technique was also used to find the probabilities of capture/ relocation within the composite home range. Spatial positions in the river were based on underwater captures/relocations and basking relocations. The results from both methods suggest that individuals at this study site use a small home range, on the order of 120 m in length, with no sex differences. These results are constrasted with those for P. floridana at the same site and with telemetrygenerated data for P. nelsoni in a shallow lake in Paynes Prairie, Florida. Sympatric P.floridana appear to have larger home ranges, with a patchier distribution of nonzero capture/relocation probabilities. Estimates of the home-range areas of P. nelsoni in the lake are an order of magnitude larger than those in the run, perhaps due to more dispersed resources or the use of telemetry for relocating animals.

Aquatic Oxygen Consumption by Wintering Red-Bellied Turtles

Aquatic Oxygen Consumption by Wintering Red-Bellied Turtles

Effects of Simulated Flooding on Metabolism and Water Balance of Turtle Eggs and Embryos

Influences of simulated flooding on metabolism and water balance of Florida red-bellied turtle (Pseudemys nelsoni) eggs and embryos were investigated. Eggs were assigned randomly to a control (non-flooding) and three flooding groups: one, three, and six days of submergence. Flooding experiments were started at day 19 of incubation. Egg mass and oxygen consumption, V O2 , of nine randomly selected eggs from each group were measured from day 19 to 43. Hatching success decreased and incubation time increased as the duration of submergence increased. No eggs in the 6-day submergence groups survived. Hatchling size did not vary among the control and submergence groups. For eggs that did not hatch, dry mass of dead embryos of the control and 1-day submergence groups was heavier than that of at day 19, and the age of dead embryos was estimated to be 42 days

Physiological effects of hypoxia on metabolism and growth of turtle embryos

Hypoxic effects on embryonic metabolism and growth of Florida red-bellied turtle ( Pseudemys nelsoni) embryo were studies. Eggs were assigned to either normoxic (21% O 2) or hypoxic (10% O 2) treatment on day 21. Oxygen consumption (V̇ O 2 ) and embryonic mass were measured periodically. On day 21 and 33, critical oxygen tension (Pc) of embryos and morphometry of blood vessels in chrioallantoic membranes were measured. Although embryos exposed to normoxia increased V̇ O 2 and mass at a rate greater than those in the hypoxic condition during incubation, both groups hatched at the same time. Hatchings from the hypoxic treatment had elevated hematoctocrit and greater relative dry ventricular mass compared to hatchings from the normoxic treatment. The Pc of hypoxic embryos was significantly lower than normoxic embryos on day 33 ( P<0.001). Morphometric comparison of blood vessels in chorioallantoic membranes revealed no significant differences except in length density on day 33 ( P<0.05). It is concluded that exposure, to chronic hypoxia resulted in retarted growth, depressed metabolism, comparable incubation period, and reduced hatchling mass. In addition, embryos exhibited some physiological plasticity which allowed increased oxygen transport in response to hypoxia.

Digestive Processing in a Herbivorous Freshwater Turtle: Consequences of Small-Intestine Fermentation

The Florida red-bellied turtle, Pseudemys nelsoni, on a diet of the aquatic plant Hydrilla verticillata, has high digestive efficiencies for dry matter, organic matter, energy, and cell walls, and moderate digestive efficiency for nitrogen. High cell wall digestibilities are a result of microbial fermentation in both the small and large intestines. Digestibilities are higher than most values reported for herbivorous reptiles on foliage diets. Mass-specific intake falls within the range measured in freefeeding herbivorous reptiles. Fermentation in the small intestine has not been reported previously in reptiles. Endproducts of fermentation-volatile fatty acids (VFAs) and gases-and concentration and rate of production of VFAs are similar to those in other herbivores. Fermentation in the small intestine has important nutritional consequences, such as a competition between endogenous enzymes and gut microflora for the highly nutritious, soluble substrate in the digesta of the small intestine. Energy from VFAs produced by the microbial fermentation approximates the total daily energy gain to P. nelsoni on a hydrilla diet. One might havepredicted, based on the large ratio ofsmall intestine length to large intestine length, that P. nelsoni would not have relied on fermentation. The shift of fermentation into the small intestine demonstrates that, at least in P. nelsoni, digestive strategy is not constrained by gut morphology.

American Alligator Food Habits in Northcentral Florida

Stomachs from 350 American alligators (Alligator mississippiensis) collected in conjunction with 1981-83 experimental harvests on 3 lakes in northcentral Florida were examined for food habits. Common invertebrate foods of subadult alligators were giant water bugs (Belostoma spp.), apple snails (Pomacea paludosa), and crayfish (Procambarus penninsulatus); common terrestrial foods were round-tailed muskrats (Neofiber alleni) and marsh rabbits (Sylvilagus palustris). Larger size classes primarily consumed Florida red-bellied turtles (Pseudemys nelsoni), peninsular cooters (P. floridana), stinkpots (Sternotherus odoratus), gizzard shad (Dorosoma cepedianum), and Florida gar (Lepisosteus platyrhincus). When compared by sex female alligators consumed significantly (P = 0.04) more mammals. Reptiles (turtles) were more important (P = 0.04) in the diet of male alligators. No differences (P > 0.05) were apparent in diets between study area lakes. Alligators in Florida consumed more fish and turtles but fewer mammals than in other parts of their range. Alligator marking tags recovered from 5% of the sample suggest some juvenile mortality may be attributable to cannibalism. Fish and amphibians are probably under-represented in the sample, and turtles, snails, crayfish, birds, and mammals may be overemphasized because of differential digestion rates. Diverse wetland habitat may benefit alligators by providing a variety of foods for different size classes. J. WILDL. MANAGE. 50(2):348-353 Carcasses collected during experimental alligator hunts in Florida provided an opportunity to conduct stomach analysis and determine the role of the alligator in Florida wetlands. Because diet influences alligator growth rate, condition, and reproduction (Chabreck 1972, McNease and Joanen 1981) food habits information may be helpful in evaluating the relationship between alligators and their management in Florida. Previous studies in Florida are limited to 36 juvenile specimens (Fogarty and Albury 1968), part (11 specimens) of a regional sample (Kellog 1929), and a report on the stomach contents of a road-killed alligator (Kinsella 1982). This paper describes the late summerearly autumn diet of alligators in northcentral Florida and relates food habits to alligator size, sex, condition, location, study year, and diges-