Developing organisms are often exposed to fluctuating environments that destabilize tissue-scale processes and induce abnormal phenotypes. This might be common in species that lay eggs in the external environment and with little parental care, such as many reptiles. In turtles, morphological development has provided striking examples of abnormal phenotypic patterns, though the influence of the environment remains unclear. To this end, we compared fluctuating asymmetry, as a proxy for developmental instability, in turtle hatchlings incubated in controlled laboratory and unstable natural conditions. Wild and laboratory hatchlings featured similar proportions of supernumerary scales (scutes) on the dorsal shell (carapace). Such abnormal scutes likely elevated shape asymmetry, which was highest in natural nests. Moreover, we tested the hypothesis that hot and dry environments cause abnormal scute formation by subjecting eggs to a range of hydric and thermal laboratory incubation regimes. Shape asymmetry was similar in hatchlings incubated at five constant temperatures (26-30°C). A hot (30°C) and severely Dry substrate yielded smaller hatchlings but scutes were not overtly affected. Our study suggests that changing nest environments contribute to fluctuating asymmetry in egg-laying reptiles, while clarifying the conditions at which turtle shell development remains buffered from the external environment.

Abstract Quantifying demographic parameters of freshwater turtle populations at the local scale is necessary in order to understand their natural history and assess their status. To examine whether maritime forest populations display different demographic traits compared to other populations, we studied the freshwater turtle assemblage at Nags Head Woods Ecological Preserve (NHWEP), located on a barrier island of North Carolina. We determined specific demographic traits such as abundance, sex ratio, size distribution, somatic growth, annual survival, and population growth rate of Snapping Turtles (Chelydra serpentina), Yellow-bellied Sliders (Trachemys scripta), Chicken Turtles (Deirochelys reticularia), and Northern Red-bellied Cooters (Pseudemys rubriventris). We determined that most demographic traits of freshwater turtle populations at NHWEP are structured similarly to other populations studied. We found that the population growth rates for three out of the four species analyzed are increasing, indicating expanding populations (with the exception of T. scripta). The annual survivorship rate for D. reticularia was similar to that of many semiaquatic turtles, contradicting previous studies for this species that have reported low annual survival because of reduced longevity. Analyzing multiple demographic traits of different freshwater turtle species within a maritime forest assemblage on a barrier island provides an important baseline on freshwater turtle demographics in unique habitats that are subject to intense environmental stochasticity.

Monitoring biodiversity over time allows for temporal comparisons of community composition and potential shifts in community resilience. We surveyed the herpetofauna assemblage at a maritime forest in Dare County, NC, during late spring and summer of 2012, which was 25 years since the last survey. Our goal was to resurvey the preserve and compare the alpha (alpha), beta (beta), and gamma (gamma) diversity values between 1987 and 2012 to quantify changes in assemblage composition using similarity indices. We found that assemblage structure became less similar temporally and spatially at the different habitats sampled but remained similar between survey years. Our study shows the importance of resurveying preserve diversity to determine shifts in assemblage and loss of biodiversity.

Once threatened with extinction, American Alligators (Alligator mississippiensis) have recovered across most of their historic range. Alligators reach the northwestern boundary of their range in Arkansas, where habitat characteristics might limit populations. Although low population densities have been dismissed by local managers as a consequence of poor habitat, no habitat studies of alligators have been performed to confirm this. It is crucial that habitat requirements of alligators throughout their range be understood for effective management and conservation. We conducted habitat assessments and population surveys for 19 bodies of water within the known range of American Alligators in southern Arkansas to determine which habitat characteristics were the most important predictors of relative population abundance. Ten habitat characteristics were incorporated into a stepwise multiple regression model with alligator relative population abundance as the dependent variable. Vegetative cover along the shoreline was the most important variable followed by land ownership (private or public). Water clarity and total vegetative cover were also important to the overall model, which explained 73% of the variation in relative population abundance. Although private water bodies had significantly higher population densities of alligators than publicly owned sites, a subsequent multi-response permutation procedure revealed no significant differences in measured habitat variables between private and publicly owned sites. Considering that measured habitat variables were not statistically different, there could be anthropogenic factors limiting American Alligators on public lands that have otherwise suitable habitat.

Abstract The geographic range of Alligator mississippiensis (American Alligator) extends to North Carolina, where information on populations is limited. In North Carolina, American Alligators are found near the coast, but typically not on the extensive barrier-island chain known as the Outer Banks. The goal of our study was to determine if habitat varied among sites occupied by American Alligators on islands—the Outer Banks and Roanoke Island—and sites on the adjacent mainland. Water depth, variance in water depth, turbidity, salinity, conductance, and pH varied among sites on Roanoke Island from sites on the mainland (P = 0.008) and the Outer Banks (P = 0.001). However, sites on the mainland and the Outer Banks were similar (P = 0.536). Ultimately, American Alligators may access the Outer Banks and find suitable habitat, but to date, little research has examined American Alligator habitat use in this portion of its geographic range; long-term occupancy is probably limited by of the effects of human disturbance and major storm events.

The Chicken Turtle, Deirochelys reticularia, is an understudied species despite the fact that it is distributed across much of the southeastern United States. In addition, no previous study has been conducted on the western subspecies, D. r. miaria, even though it is considered rare and possibly in decline within portions of its range. A capture recapture study was conducted over 3 yr on a population of D. r. miaria in central Arkansas to determine demographic and reproductive characteristics. The population approached a male bias (1.9:1) and consisted of few total individuals (N = 42). Reproductive-traits, including clutch, egg, and hatchling size, appear to be similar between D. r. miaria and eastern populations. Annual survival estimates were similar among males, females, and juveniles (0.70, 0.70, and 0.69, respectively) and did not change over the course of the study. Although low compared with most turtles, similar results have been reported for other populations of D. reticularia, which suggests that the species may have a different life-history strategy than that of most other chelonians. Due to this difference, management practices are likely to affect D. r. miaria differently from other turtle species.

Very little is known about the population dynamics of American alligators in northern latitudes. To better define the characteristics of the northern population, we combined published life-history and vital rate data for studies conducted in North Carolina and South Carolina; for comparison, we gleaned the same information from the literature for the southern (Florida and Louisiana) population. We constructed a 5-stage Lefkovitch matrix model for each population. The models showed that the southern population was stable and slightly increasing (lambda = 1.02), whereas the northern population was in decline (lambda = 0.870). We integrated potential impacts of climate change into the northern population model to determine how the population might respond to increased temperature and decreased precipitation. An increase in temperature would benefit the northern population; however, a decrease in precipitation or the combined effects of temperature increase and precipitation decrease would negatively affect the viability of the northern population. Two priorities result from modeling these scenarios: 1) a long-term monitoring program is needed to acquire the life-history and vital rate data on the northern population, and 2) current alligator habitat must be conserved or improved to insulate the species from potential drought associated with climate change. (C) 2014 The Wildlife Society.

Following perturbations like commercial harvests, turtles are susceptible to population declines because of life history characteristics such as long generation times, low recruitment rates, delayed maturity, and slow growth rates. Prior to gaining state-wide protection in 1993, the Alligator Snapping Turtle (Macrochelys temminckii) was commercially harvested in Arkansas. We conducted a mark-recapture study from 2005-2007 on a population of M. temminckii known to have been harvested in the East Fork Cadron Creek, a slow-moving stream in central Arkansas and part of the Mississippi River drainage. Captured turtles were marked, measured, weighed, and sexed. We compared observed characteristics to what would be expected if this population did not exhibit any evidence of past commercial harvest. We caught few large adults and approximately one adult for every juvenile. The adult sex ratio was highly female biased (6 F:1 M). Population density (18 turtles/km stream reach) was slightly lower than expected. The apparent survivorship for males (0.96), females (0.88), and juveniles (0.80) appear to be as expected for a large freshwater turtle. Whereas high survivorship rates may ameliorate the effects of historical commercial harvest, slow growth rates, low reproductive success, and long generation times have assured these effects to be long lasting and still present within our study population. We also suggest that there are factors impeding recovery of this population, such as life history characteristics and incidental catch by fisherman.

Conspecific turtle populations typically exhibit variation In demographic and reproductive traits such as adult size, growth rate, sex ratio, and clutch size. Variation In these traits has been previously correlated to variation In local environmental conditions, latitude, and habitats. Given that some turtle species have large geographic ranges and occur In a variety of habitats, It Is imperative to determine how traits differ throughout the species' range. Towards this end, we examined demographic and reproductive traits of Blanding's Turtles (Emydoidea blandingii) In Grant County, Nebraska over the span of six years. The population's sex ratio was female biased (0.7:1.0, M:F) and skewed towards large, adult turtles (5:1, adult:juvenile). The analysis of adult survivorship suggests that female turtles (59% annual survivorship) may be experiencing greater mortality rates compared to males (90% annual survivorship), possibly due to road mortality. Unlike all previous reports, analyses of reproductive parameters Indicate that turtles In the western Nebraska population do not Increase clutch size with body size. Rather, egg size Increases as body size Increases, which may help reduce desiccation rates of the eggs In an arid environment. Optimal egg size may not be reached due to pelvic width constraints of females. Comparisons of our findings with those of other Blanding's Turtle studies are discussed.

Overwintering habits of hatchling Blanding's turtles (Emydoidea blandingii) are unknown. To determine whether these turtles are able to survive winter in aquatic habitats, we submerged hatchlings in normoxic (155 mmHg Po2) and hypoxic (6 mmHg Po2) water at 4 degrees C, recording survival times and measuring changes in key physiological variables. For comparison, we simultaneously studied hatchling softshell (Apalone spinifera) and snapping (Chelydra serpentina) turtles, which are known to overwinter in aquatic habitats. In normoxic water, C. serpentina and A. spinifera survived to the termination of the experiment (76 and 77 d, respectively). Approximately one-third of the E. blandingii died during 75 d of normoxic submergence, but the cause of mortality was unclear. In hypoxic water, average survival times were 6 d for A. spinifera, 13 d for E. blandingii, and 19 d for C. serpentina. Mortality during hypoxic submergence was probably caused by metabolic acidosis, which resulted from accumulated lactate. Unlike the case with adult turtles, our hatchlings did not increase plasma calcium and magnesium, nor did they sequester lactate within the shell. Our results suggest that hatchling E. blandingii are not particularly well suited to hibernation in hypoxic aquatic habitats.