Tissue and Temperature-Specific RNA-Seq Analysis Reveals Genomic Versatility and Adaptive Potential in Wild Sea Turtle Hatchlings (Caretta caretta).

Background: Digital transcriptomics is rapidly emerging as a powerful new technology for modelling the environmental dynamics of the adaptive landscape in diverse lineages. This is particularly valuable in taxa such as turtles and tortoises (order Testudines) which contain a large fraction of endangered species at risk due to anthropogenic impacts on the environment, including pollution, overharvest, habitat degradation, and climate change. Sea turtles (family Cheloniidae) in particular invite a genomics-enabled approach to investigating their remarkable portfolio of adaptive evolution. The sex of the endangered loggerhead sea turtle (Caretta caretta) is subject to temperature-dependent sex determination (TSD), a mechanism by which exposure to temperatures during embryonic development irreversibly determines sex. Higher temperatures produce mainly female turtles and lower temperatures produce mainly male turtles. Incubation temperature can have long term effects on the immunity, migratory ability, and ultimately longevity of hatchlings. We perform RNA-seq differential expression analysis to investigate tissue- and temperature-specific gene expression within brain (n = 7) and gonadal (n = 4) tissue of male and female loggerhead hatchlings. Results: We assemble tissue- and temperature-specific transcriptomes and identify differentially expressed genes relevant to sexual development and life history traits of broad adaptive interest to turtles and other amniotic species. We summarize interactions among differentially expressed genes by producing network visualizations, and highlight shared biological pathways related to migration, immunity, and longevity reported in the avian and reptile literature. Conclusions: The measurement of tissue- and temperature-specific global gene expression of an endangered, flagship species such as the loggerhead sea turtle (Caretta caretta) reveals the genomic basis for potential resiliency and is crucial to future management and conservation strategies with attention to changing climates. Brain and gonadal tissue collected from experimentally reared loggerhead male and female hatchlings comprise an exceedingly rare dataset that permits the identification of genes enriched in functions related to sexual development, immunity, longevity, and migratory behavior and will serve as a large, new genomic resource for the investigation of genotype-phenotype relationships in amniotes.

Gas embolism and massive blunt force trauma to sea turtles entrained in hopper dredges in North and South Carolina, USA.

Decompression sickness (DCS) has been described mainly in loggerhead turtles Caretta caretta bycaught in trawls and gillnets. Here we present cases of gas emboli (GE) in 8 green turtles Chelonia mydas and 2 Kemp's ridleys Lepidochelys kempii entrained in hopper dredges that were working at 8.8-15.2 m depths during shipping channel maintenance or beach renourishment activities. Turtle weights ranged from 2.2 to 6.7 kg. All were found alive with blunt force injuries from passage through the dredge and were taken to rehabilitation facilities. Four green turtles died or were euthanized within 24 h. Six turtles survived. Radiographic or ultrasonographic evidence of GE was detected in 4 turtles, including 3 mortalities. Computed tomography (CT) revealed perirenal and cervical GE in 4 turtles, including 1 mortality. No GE were detected in 2 of the survivors. Upon necropsy, GE were found in mesenteric vessels, the right atrium, and kidneys. Histopathology confirmed that tissues were in a good state of preservation without evidence of bacterial overgrowth or putrefactive gas formation. Death likely resulted primarily from massive tissue trauma from the dredge, but moderate GE could have led to DCS and complicated recovery. The surviving turtles weighed less than those that did not survive. Besides hypothesized stress/exercise-induced circulatory changes of blood through the lungs and pressure reduction of forced surfacing from depth, drastic pressure change within the dredge pipes before and after the pump could contribute to GE. Hopper dredge entrainment is an additional cause of GE and potential DCS in sea turtles.

Identifying patterns in foraging-area origins in breeding aggregations of migratory species: Loggerhead turtles in the Northwest Atlantic.

Population assessments conducted at reproductive sites of migratory species necessitate understanding the foraging-area origins of breeding individuals. Without this information, efforts to contextualize changes in breeding populations and develop effective management strategies are compromised. We used stable isotope analysis of tissue samples collected from loggerhead sea turtles (Caretta caretta) nesting at seven sites in the Northern Recovery Unit (NRU) of the eastern United States (North Carolina, South Carolina and Georgia) to assign females to three separate foraging areas in the Northwest Atlantic Ocean (NWA). We found that the majority of the females at NRU nesting sites (84.4%) use more northern foraging areas in the Mid-Atlantic Bight, while fewer females use more proximate foraging areas in the South Atlantic Bight (13.4%) and more southerly foraging areas in the Subtropical Northwest Atlantic (2.2%). We did not find significant latitudinal or temporal trends in the proportions of NRU females originating from different foraging areas. Combining these findings with previous data from stable isotope and satellite tracking studies across NWA nesting sites showed that variation in the proportion of adult loggerheads originating from different foraging areas is primarily related differences between recovery units: individuals in the NRU primarily use the Mid-Atlantic Bight foraging area, while individuals from the three Florida recovery units primarily use the Subtropical Northwest Atlantic and Eastern Gulf of Mexico foraging areas. Because each foraging area is associated with its own distinct ecological characteristics, environmental fluctuations and anthropogenic threats that affect the abundance and productivity of individuals at nesting sites, this information is critical for accurately evaluating population trends and developing effective region-specific management strategies.

Recent advances on the estimation of the thermal reaction norm for sex ratios.

Temperature-dependent sex determination, or TSD, is a widespread phenomenon in reptiles. The shape of the relationship between constant incubation temperature and sex ratio defines the TSD pattern. The TSD pattern is considered a life-history parameter important for conservation because the wider the range of temperatures producing both sexes, the more resilient the species is to climate change impacts. We review the different published equations and methodologies that have been used to model TSD patterns. We describe a new flexible model that allows for an asymmetrical pattern around the pivotal temperature, which is the constant temperature producing both sexes in equal proportions. We show that Metropolis-Hastings with Markov chain produced by a Monte Carlo process has many advantages compared to maximum likelihood and is preferred. Finally, we apply the models to results from incubation experiments using eggs from the marine turtle Lepidochelys olivacea originating in Northeast Indian, East Pacific, and West Atlantic Regional Management Units (RMUs) and find large differences in pivotal temperatures but not in transitional ranges of temperatures.

Crude Oil and Dispersant Cause Acute Clinicopathological Abnormalities in Hatchling Loggerhead Sea Turtles (Caretta caretta).

Following the explosion of the Deepwater Horizon MC252 oil rig in 2010, 319 live sea turtles exposed to crude oil and oil-dispersant (Corexit) combinations were admitted to rehabilitation centers for decontamination and treatment. Treatment of oiled sea turtles was guided by expected physiological and pathological effects of crude oil exposure extrapolated from studies in other species and from a single loggerhead sea turtle (Caretta caretta) study. While invaluable starting points, inherent limitations to extrapolation, and small sample size of the experimental exposure study, reduce their utility for clinical guidance and for assessing oil spill impacts. Effects of dispersants were not included in the previous experimental exposure study, and cannot be effectively isolated in the analysis of field data from actual spills. A terminal study of pivotal temperature of sex determination using eggs salvaged from doomed loggerhead nests provided an opportunity for an ancillary exposure study to investigate the acute effects of crude oil, dispersant, and a crude oil/dispersant combination in sea turtle hatchlings. Eggs were incubated at 27.2-30.8°C, and hatchlings were randomly assigned to control, oil, dispersant, and combined oil/dispersant exposures for 1 or 4 days. Contaminant exposures were started after a 3 day post-hatching period simulating nest emergence. Turtles were placed in individual glass bowls containing aged seawater and exposed to oil (Gulf Coast-Mixed Crude Oil Sweet, CAS #8002-05-9, 0.833 mL/L) and/or dispersant (Corexit 9500A, 0.083 mL/L), replicating concentrations encountered during oil spills and subsequent response. Statistically significant differences between treatments and non-exposed controls were detected for PCV, AST, uric acid, glucose, calcium, phosphorus, total protein, albumin, globulin, potassium, and sodium. The principal dyscrasias reflected acute osmolar, electrolyte and hydration challenges that were more numerous and greater in combined oil/dispersant exposures at 4 days. Clinicopathological findings were supported by a failure to gain weight (associated with normal hatchling hydration in seawater) in dispersant and combination exposed hatchlings. These findings can help guide clinical response for sea turtles exposed to crude oil and crude oil/dispersant combinations, and indicate potential impacts on wildlife to consider when deploying dispersants in an oil spill response.

NMR Metabolomic Analysis of Skeletal Muscle, Heart, and Liver of Hatchling Loggerhead Sea Turtles (Caretta caretta) Experimentally Exposed to Crude Oil and/or Corexit.

We used nuclear magnetic spectroscopy (NMR) to evaluate the metabolic impacts of crude oil, Corexit 5900A, a dispersant, and a crude oil Corexit 5900A mixture exposure on skeletal muscle, heart, and liver physiology of hatchling loggerhead sea turtles (Caretta caretta). Tissue samples were obtained from 22 seven-day-old hatchlings after a four day cutaneous exposure to environmentally relevant concentrations of crude oil, Corexit 5900A, a combination of crude oil and Corexit 9500A, or a seawater control. We identified 38 metabolites in the aqueous extracts of the liver, and 30 metabolites in both the skeletal and heart muscle aqueous extracts, including organic acids/osmolytes, energy compounds, amino acids, ketone bodies, nucleosides, and nucleotides. Skeletal muscle lactate, creatines, and taurine concentrations were significantly lower in hatchlings exposed to crude oil than in control hatchlings. Lactate, taurine, and cholines appeared to be the basis of some variation in hatchling heart samples, and liver inosine, uracil, and uridine appeared to be influenced by Corexit and crude oil exposure. Observed decreases in concentrations of lactate and creatines may reflect energy depletion in skeletal muscle of oil-exposed animals, while decreased taurine concentrations in these animals may reflect higher oxidative stress.

Microplastic ingestion ubiquitous in marine turtles.

Despite concerns regarding the environmental impacts of microplastics, knowledge of the incidence and levels of synthetic particles in large marine vertebrates is lacking. Here, we utilize an optimized enzymatic digestion methodology, previously developed for zooplankton, to explore whether synthetic particles could be isolated from marine turtle ingesta. We report the presence of synthetic particles in every turtle subjected to investigation (n = 102) which included individuals from all seven species of marine turtle, sampled from three ocean basins (Atlantic [ATL]: n = 30, four species; Mediterranean (MED): n = 56, two species; Pacific (PAC): n = 16, five species). Most particles (n = 811) were fibres (ATL: 77.1% MED: 85.3% PAC: 64.8%) with blue and black being the dominant colours. In lesser quantities were fragments (ATL: 22.9%: MED: 14.7% PAC: 20.2%) and microbeads (4.8%; PAC only; to our knowledge the first isolation of microbeads from marine megavertebrates). Fourier transform infrared spectroscopy (FT-IR) of a subsample of particles (n = 169) showed a range of synthetic materials such as elastomers (MED: 61.2%; PAC: 3.4%), thermoplastics (ATL: 36.8%: MED: 20.7% PAC: 27.7%) and synthetic regenerated cellulosic fibres (SRCF; ATL: 63.2%: MED: 5.8% PAC: 68.9%). Synthetic particles being isolated from species occupying different trophic levels suggest the possibility of multiple ingestion pathways. These include exposure from polluted seawater and sediments and/or additional trophic transfer from contaminated prey/forage items. We assess the likelihood that microplastic ingestion presents a significant conservation problem at current levels compared to other anthropogenic threats.

1H-NMR metabolomic study of whole blood from hatchling loggerhead sea turtles (Caretta caretta) exposed to crude oil and/or Corexit.

We used proton nuclear magnetic resonance spectroscopy (1H-NMR) to evaluate metabolic impacts of environmentally relevant crude oil and Corexit exposures on the physiology of hatchling loggerhead sea turtles (Caretta caretta). Sample extraction and data acquisition methods for very small volume whole blood samples and sources of variation between individual hatchlings were assessed. Sixteen unclotted, whole blood samples were obtained from 7-day-old hatchlings after a 4-day cutaneous exposure to either control seawater, crude oil, Corexit 9500A or a combination of crude oil and Corexit 9500A. After extraction, one- and two-dimensional 1H-NMR spectra of the samples were obtained, and 17 metabolites were identified and confirmed in the whole blood spectra. Variation among samples due to the concentrations of metabolites 3-hydroxybutyrate, lactate, trimethylamine oxide and propylene glycol did not statistically correlate with treatment group. However, the characterization of the hatchling loggerhead whole blood metabolome provides a foundation for future metabolomic research with sea turtles and a basis for the study of tissues from exposed hatchling sea turtles.

Conservation hotspots for marine turtle nesting in the United States based on coastal development.

Coastal areas provide nesting habitat for marine turtles that is critical for the persistence of their populations. However, many coastal areas are highly affected by coastal development, which affects the reproductive success of marine turtles. Knowing the extent to which nesting areas are exposed to these threats is essential to guide management initiatives. This information is particularly important for coastal areas with both high nesting density and dense human development, a combination that is common in the United States. We assessed the extent to which nesting areas of the loggerhead (Caretta caretta), the green (Chelonia mydas), the Kemp's ridley (Lepidochelys kempii), and leatherback turtles (Dermochelys coriacea) in the continental United States are exposed to coastal development and identified conservation hotspots that currently have high reproductive importance and either face high exposure to coastal development (needing intervention), or have low exposure to coastal development, and are good candidates for continued and future protection. Night-time light, housing, and population density were used as proxies for coastal development and human disturbance. About 81.6% of nesting areas were exposed to housing and human population, and 97.8% were exposed to light pollution. Further, most (>65%) of the very high- and high-density nesting areas for each species/subpopulation, except for the Kemp's ridley, were exposed to coastal development. Forty-nine nesting sites were selected as conservation hotspots; of those high-density nesting sites, 49% were sites with no/low exposure to coastal development and the other 51% were exposed to high-density coastal development. Conservation strategies need to account for ~66.8% of all marine turtle nesting areas being on private land and for nesting sites being exposed to large numbers of seasonal residents.

Evaluating the landscape of fear between apex predatory sharks and mobile sea turtles across a large dynamic seascape.

The "landscape of fear" model has been proposed as a unifying concept in ecology, describing, in part, how animals behave and move about in their environment. The basic model predicts that as an animal's landscape changes from low to high risk of predation, prey species will alter their behavior to risk avoidance. However, studies investigating and evaluating the landscape of fear model across large spatial scales (tens to hundreds of thousands of square kilometers) in dynamic, open, aquatic systems involving apex predators and highly mobile prey are lacking. To address this knowledge gap, we investigated predator-prey relationships between. tiger sharks (Galeocerdo cuvier) and loggerhead turtles (Caretta caretta) in the North Atlantic Ocean. This included the use of satellite tracking to examine shark and turtle distributions as well as their surfacing behaviors under varying levels of home range overlap. Our findings revealed patterns that deviated from our a priori predictions based on the landscape of fear model. Specifically, turtles did not alter their surfacing behaviors to risk avoidance when overlap in shark-turtle core home range was high. However, in areas of high overlap with turtles, sharks exhibited modified surfacing behaviors that may enhance predation opportunity. We suggest that turtles may be an important factor in determining shark,distribution, whereas for turtles, other life history trade-offs may play a larger role in defining their habitat use. We propose that these findings are a result of both biotic and physically driven factors that independently or synergistically affect predator-prey interactions in this system. These results have implications for evolutionary biology, community ecology; and wildlife conservation. Further, given the difficulty in studying highly migratory marine species, our approach and conclusions may be applied to the study of other predator-prey systems.

Clinical pathology reference intervals for an in-water population of juvenile loggerhead sea turtles (Caretta caretta) in Core Sound, North Carolina, USA.

The loggerhead sea turtle (Caretta caretta) is found throughout the waters of the Atlantic, Pacific, and Indian Oceans. It is a protected species throughout much of its range due to threats such as habitat loss, fisheries interactions, hatchling predation, and marine debris. Loggerheads that occur in the southeastern U.S. are listed as "threatened" on the U.S. Endangered Species List, and receive state and federal protection. As part of an on-going population assessment conducted by the National Marine Fisheries Service, samples were collected from juvenile loggerhead sea turtles in Core Sound, North Carolina, between 2004 and 2007 to gain insight on the baseline health of the threatened Northwest Atlantic Ocean population. The aims of the current study were to establish hematologic and biochemical reference intervals for this population, and to assess variation of the hematologic and plasma biochemical analytes by season, water temperature, and sex and size of the turtles. Reference intervals for the clinical pathology parameters were estimated following Clinical Laboratory Standards Institute guidelines. Season, water temperature, sex, and size of the turtles were found to be significant factors of variation for parameter values. Seasonal variation could be attributed to physiological effects of decreasing photoperiod, cooler water temperature, and migration during the fall months. Packed cell volume, total protein, and albumin increased with increasing size of the turtles. The size-related differences in analytes documented in the present study are consistent with other reports of variation in clinical pathology parameters by size and age in sea turtles. As a component of a health assessment of juvenile loggerhead sea turtles in North Carolina, this study will serve as a baseline aiding in evaluation of trends for this population and as a diagnostic tool for assessing the health and prognosis for loggerhead sea turtles undergoing rehabilitation.

Incubation temperature effects on hatchling performance in the loggerhead sea turtle (Caretta caretta).

Incubation temperature has significant developmental effects on oviparous animals, including affecting sexual differentiation for several species. Incubation temperature also affects traits that can influence survival, a theory that is verified in this study for the Northwest Atlantic loggerhead sea turtle (Caretta caretta). We conducted controlled laboratory incubations and experiments to test for an effect of incubation temperature on performance of loggerhead hatchlings. Sixty-eight hatchlings were tested in 2011, and 31 in 2012, produced from eggs incubated at 11 different constant temperatures ranging from 27°C to 33°C. Following their emergence from the eggs, we tested righting response, crawling speed, and conducted a 24-hour long swim test. The results support previous studies on sea turtle hatchlings, with an effect of incubation temperature seen on survivorship, righting response time, crawling speed, change in crawl speed, and overall swim activity, and with hatchlings incubated at 27°C showing decreased locomotor abilities. No hatchlings survived to be tested in both years when incubated at 32°C and above. Differences in survivorship of hatchlings incubated at high temperatures are important in light of projected higher sand temperatures due to climate change, and could indicate increased mortality from incubation temperature effects.

Spatio-temporal variation in the incubation duration and sex ratio of hawksbill hatchlings: implication for future management.

Climate change poses a unique threat to species with temperature dependent sex determination (TSD), such as marine turtles, where increases in temperature can result in extreme sex ratio biases. Knowledge of the primary sex ratio of populations with TSD is key for providing a baseline to inform management strategies and to accurately predict how future climate changes may affect turtle populations. However, there is a lack of robust data on offspring sex ratio at appropriate temporal and spatial scales to inform management decisions. To address this, we estimate the primary sex ratio of hawksbill hatchlings, Eretmochelys imbricata, from incubation duration of 5514 in situ nests from 10 nesting beaches from two regions in Brazil over the last 27 years. A strong female bias was estimated in all beaches, with 96% and 89% average female sex ratios produced in Bahia (BA) and Rio Grande do Norte (RN). Both inter-annual (BA, 88 to 99%; RN, 75 to 96% female) and inter-beach (BA, 92% to 97%; RN, 81% to 92% female) variability in mean offspring sex ratio was observed. These findings will guide management decisions in Brazil and provide further evidence of highly female-skew sex ratios in hawksbill turtles.

Ghrelin and leptin modulate the feeding behaviour of the hawksbill turtle Eretmochelys imbricata during nesting season.

Female sea turtles have rarely been observed foraging during the nesting season. This suggests that prior to their migration to nesting beaches the females must store sufficient energy and nutrients at their foraging grounds and must be physiologically capable of undergoing months without feeding. Leptin (an appetite-suppressing protein) and ghrelin (a hunger-stimulating peptide) affect body weight by influencing energy intake in all vertebrates. We investigated the levels of these hormones and other physiological and nutritional parameters in nesting hawksbill sea turtles in Rio Grande do Norte State, Brazil, by collecting consecutive blood samples from 41 turtles during the 2010-2011 and 2011-2012 reproductive seasons. We found that levels of serum leptin decreased over the nesting season, which potentially relaxed suppression of food intake and stimulated females to begin foraging either during or after the post-nesting migration. Concurrently, we recorded an increasing trend in ghrelin, which may have stimulated food intake towards the end of the nesting season. Both findings are consistent with the prediction that post-nesting females will begin to forage, either during or immediately after their post-nesting migration. We observed no seasonal trend for other physiological parameters (values of packed cell volume and serum levels of alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, γ-glutamyl transferase, low-density lipoprotein, and high-density lipoprotein). The observed downward trends in general serum biochemistry levels were probably due to the physiological challenge of vitellogenesis and nesting in addition to limited energy resources and probable fasting.

Comparison of mercury burdens in chronically debilitated and healthy loggerhead sea turtles (Caretta caretta).

An increase in the incidence of debilitated loggerhead sea turtle (Caretta caretta) strandings in the southeastern United States has been observed in recent years. These turtles are characterized by emaciation and heavy burdens of external and internal parasites, and bacterial infections, but the underlying cause of their condition is unknown. To investigate further the causes of these strandings, a health assessment was performed on stranded, debilitated loggerhead turtles, and contaminant concentrations in various tissues were compared to those from healthy turtles. This portion of the study investigated the potential role of mercury (Hg) toxicity in the debilitated condition described above. Hematocrit, total protein, albumin, globulin, glucose, calcium, lymphocyte counts, heterophil:lymphocyte ratios, aspartate aminotransferase, uric acid, sodium, and chloride were altered in debilitated loggerheads relative to healthy animals. However, none of the aforementioned health indicators correlated with Hg concentrations in either red blood cells (RBCs) or plasma. The Hg concentration in RBCs was 129+/-72 (mean+/-standard deviation) times higher than in plasma, causing a significant dilution of Hg in whole blood due to extreme anemia. Mercury concentrations in RBCs (73.7+/-21.2 ng/g) and scutes (455+/-57 ng/g) from debilitated turtles were similar to or lower than those reported for healthy animals, indicating no elevation in Hg exposure before and during the progression of this condition. These findings suggest that Hg toxicity does not play a role in the debilitated loggerhead condition observed in the southeastern United States.

Regional management units for marine turtles: a novel framework for prioritizing conservation and research across multiple scales.

BACKGROUND: Resolving threats to widely distributed marine megafauna requires definition of the geographic distributions of both the threats as well as the population unit(s) of interest. In turn, because individual threats can operate on varying spatial scales, their impacts can affect different segments of a population of the same species. Therefore, integration of multiple tools and techniques--including site-based monitoring, genetic analyses, mark-recapture studies and telemetry--can facilitate robust definitions of population segments at multiple biological and spatial scales to address different management and research challenges. METHODOLOGY/PRINCIPAL FINDINGS: To address these issues for marine turtles, we collated all available studies on marine turtle biogeography, including nesting sites, population abundances and trends, population genetics, and satellite telemetry. We georeferenced this information to generate separate layers for nesting sites, genetic stocks, and core distributions of population segments of all marine turtle species. We then spatially integrated this information from fine- to coarse-spatial scales to develop nested envelope models, or Regional Management Units (RMUs), for marine turtles globally. CONCLUSIONS/SIGNIFICANCE: The RMU framework is a solution to the challenge of how to organize marine turtles into units of protection above the level of nesting populations, but below the level of species, within regional entities that might be on independent evolutionary trajectories. Among many potential applications, RMUs provide a framework for identifying data gaps, assessing high diversity areas for multiple species and genetic stocks, and evaluating conservation status of marine turtles. Furthermore, RMUs allow for identification of geographic barriers to gene flow, and can provide valuable guidance to marine spatial planning initiatives that integrate spatial distributions of protected species and human activities. In addition, the RMU framework--including maps and supporting metadata--will be an iterative, user-driven tool made publicly available in an online application for comments, improvements, download and analysis.

Using telemetry to mitigate the bycatch of long-lived marine vertebrates.

The unintended bycatch of long-lived marine species in fishing gear is an important global conservation issue. One suite of management approaches used to address this problem restricts or modifies fishing practices in areas where the probability of bycatch is believed to be high. Information on the distribution and behavior of the bycaught species is a desirable component of any such scheme, but such observations are often lacking. We describe a spatially explicit approach that combines data on the distribution of fishing effort and observations of the distribution of bycatch species derived from satellite telemetry. In a case study, we used a spatially explicit predator-prey model to investigate real-time interactions between three species of sea turtles (Caretta caretta, Chelonia mydas, and Lepidochelys kempii) and the fall large-mesh gill net fishery that targets southern flounder (Paralichthys lethostigma) in Pamlico Sound, North Carolina between 2002 and 2004. The model calculates a spatial overlap index, thereby allowing us to identify which fishing areas have the greatest risk of encountering bycatch. In this study, our telemetry deployments (n = 50) were designed specifically to address existing fisheries conservation measures in Pamlico Sound intended to reduce sea turtle bycatch. We were able to predict the spatial distribution of bycatch and evaluate management measures. This approach offers a powerful tool to managers faced with the need to reduce bycatch.

Temperature-dependent sex determination and global change: are some species at greater risk?

In species with temperature-dependent sex determination (TSD), global climate change may result in a strong sex ratio bias that could lead to extinction. The relationship between sex ratio and egg incubation at constant temperature in TSD species is characterized by two parameters: the pivotal temperature (P) and the transitional range of temperature that produces both sexes (TRT). Here, we show that the proportion of nests producing both sexes is positively correlated to the width of the TRT by a correlative approach from sex ratio data collected in the literature and by simulations of TSD using a mechanistic model. From our analyses, we predict that species with a larger TRT should be more likely to evolve in response to new thermal conditions, thus putting them at lower risk to global change.