Commercial harvest and export of snapping turtles (Chelydra serpentina) in the United States: trends and the efficacy of size limits at reducing harvest

As Asian turtle populations have crashed, China has increasingly turned to international import to meet domestic demand, which has increased pressure on global turtle populations. Snapping turtles (Chelydra serpentina) are being harvested in unprecedented numbers in the United States (US) to meet the needs of this international market. Here we report US snapping turtle live export from 1999 to 2013, and for the first time test the effectiveness of size limits in reducing commercial harvest numbers. Over three million live snapping turtles from farm and wild caught stock were exported from the US to Asia in 2012–14 alone. Increases in the export of wild caught snapping turtles to over 200,000 individuals in 2012 and 2014, compared to under 50,000 in other years, may indicate that farms are becoming unable to keep up with increasing demand. Annual harvest pressure at the state level increased linearly from 1998 to 2013, mirroring trends in federal export over the same time period. Our model estimates that size-limits were effective at reducing harvest by 30–87% in years with high harvest pressure. However, the majority of size limit regulations result in the removal of larger breeding adults, which has been shown to be detrimental to long term population viability. Regulatory approaches dedicated to the long term management of this iconic species will need to balance the short term gains, in the form of reduced harvest rates, with long term population viability.     

Roads as barriers to animal movement in fragmented landscapes

Roads can act as barriers to animal movement through mortality during crossing attempts or behavioral avoidance. This barrier effect has negative demographic and genetic consequences that can ultimately result in local or regional extinction. Here we use radio-telemetry data on three terrestrial vertebrates (eastern massasauga Sistrurus catenatus , eastern box turtle Terrapene carolina and ornate box turtle Terrapene ornata ) to test whether roads acted as barriers to movement. Specifically, we test whether individuals avoided crossing roads by comparing the number of observed crossings with the number of road crossings predicted by randomizations of individual movement paths. All species crossed roads significantly less often than predicted by chance, indicating strong road avoidance. Results of this study showing behavioral avoidance and previous studies on road mortality indicate that roads are strong barriers to these species. High mortality during crossing attempts would select for road avoidance, reducing the number of individuals killed on roads over time but leading to genetically partitioned subpopulations due to a lack of gene flow. In species that are long-lived and late-maturing, negative genetic effects might not be observable over short time-scales, thus placing populations at high risk of extinction because of a failure to detect an incrementally worsening problem. Formulating successful management strategies for many species in decline will require integrating data on road mortality, animal behavior and population genetics in order to understand more clearly the barrier effect of roads.     

鳖油的制备及其理化性质研究

利用传统炮制方法制备了鳖油 ,其得率为 5 8.31% ,并测定了其含量、酸价及皂化值等理化数据。其中多不饱和脂肪酸质量分数为 42 .47% ,GC分析结果二十碳五烯酸及二十二碳六烯酸烯质量分数分别为 14.82 %、19.10 %。     

Climate change and sea turtles: a 150-year reconstruction of incubation temperatures at a major marine turtle rookery

Sea turtles show temperature dependent sex determination. Using an empirical relationship between sand and air temperature, we reconstructed the nest temperatures since 1855 at Ascension Island, a major green turtle (Chelonia mydas) rookery. Our results show that inter‐beach thermal variations, previously ascribed to the albedo of the sand, which varies hugely from one beach to another, have persisted for the last century. Reconstructed nest temperatures varied by only 0.5 °C on individual beaches over the course of the nesting season, while the temperature difference between two key nesting beaches was always around 3 °C. Hence inter‐beach thermal variations are the main factor causing a large range of incubation temperatures at this rookery. There was a general warming trend for nests, with a mean increase in reconstructed nest temperatures for different months of between 0.36 and 0.49 °C for the last 100 years.     

Role of neuroglobin in regulating reactive oxygen species in the brain of the anoxia-tolerant turtle Trachemys scripta

Neuroglobin (Ngb) is an oxygen binding heme protein found in nervous tissue with a yet unclear physiological and protective role in the hypoxia-sensitive mammalian brain. Here we utilized in vivo and in vitro studies to examine the role of Ngb in anoxic and post-anoxic neuronal survival in the freshwater turtle. We employed semiquantitative RT-PCR and western blotting to analyze Ngb mRNA and protein levels in turtle brain and neuronally enriched cultures. Ngb expression is strongly up-regulated by hypoxia and post-anoxia reoxygenation but increases only modestly in anoxia. The potential neuroprotective role of Ngb in this species was analyzed by knocking down Ngb using specific small interfering RNA. Ngb knockdown in neuronally enriched cell cultures resulted in significant increases in H₂O₂ release compared to controls but no change in cell death. Cell survival may be linked to activation of other protective responses such as the extracellular regulated kinase transduction pathway, as phosphorylated extracellular regulated kinase levels in anoxia were significantly higher in Ngb knockdown cultures compared to controls. The greater expression of Ngb when reactive oxygen species are likely to be high, and the increased susceptibility of neurons to H₂O₂ release and external oxidative stress in knockdown cultures, suggests a role for Ngb in reducing reactive oxygen species production or in detoxification, though it does not appear to be of primary importance in the anoxia tolerant turtle in the presence of compensatory survival mechanisms.     

The Effects of Artificial Beach Nourishment on Marine Turtles: Differences between Loggerhead and Green Turtles

Marine turtle reproductive success is correlated with the stability and quality of the nesting environment. Female marine turtles show fidelity to nesting beaches, making artificial beach nourishment practices directly relevant to their recovery. We evaluated the impacts of artificial beach nourishment on Loggerhead ( Caretta caretta ) and Green turtles ( Chelonia mydas ) between artificially nourished and nonnourished beaches. We observed reduced nesting success (ratio of nesting emergences to emergences not resulting in nest deposition) for both species. This negative effect lasted for one season in Loggerheads and for at least one season in Green turtles. Physical attributes of the fill sand did not impede nesting attempts. We argue that the decrease in nesting success resulted from an altered beach profile not favorable for nest deposition, which subsequently improved in later seasons as the beach equilibrated to a more natural slope. We observed a 52.2% decrease in reproductive output (hatchlings km⁻¹ yr⁻¹) for Loggerheads one year postnourishment, with a 44.1% increase observed the two seasons postnourishment. In Green turtles, a 0.8% reduction was observed the first season postnourishment, despite a 13% increase in the nonnourished area. The reduction in reproductive output in both cases was primarily a consequence of decreased nesting success, lowering nest numbers. These results reveal stronger negative effects of beach nourishment on Loggerheads compared to Green turtles and the importance of minimizing excessive nonnesting emergences associated with artificial beach nourishment. Nourished areas also experienced more than 600% increase in the number of Loggerhead hatchlings disoriented by artificial lighting over two years postnourishment.     

Development of microsatellite markers in the Australasian snake-necked turtle Chelodina rugusa and cross-species amplification

Seventeen microsatellite loci were developed for the snake-necked turtle, Chelodina rugosa (Ogilby, 1890). Sixteen of the loci were polymorphic but three of these loci had null alleles. One locus displayed linkage disequilibrium. These 17 markers were tested for amplification in eight congeneric species with varying success; 98% amplification in Chelodina burrungandjii, 72% in C. canni, 38% in C. expansa, 58% in C. longicollis, 67% in C. mccordi, 73% in C. oblonga, 81% in C. parkeri, and 68% in C. pritchardi. These microsatellite markers will be useful for population assignment, gene flow, mating systems and hybridization studies in the genus Chelodina.     

Directional gene flow patterns in disjunct populations of the black ratsnake (Pantheropis obsoletus) and the Blanding’s turtle (Emydoidea blandingii)

The estimation and maintenance of connectivity among local populations is an important conservation goal for many species at risk. We used Bayesian statistics and coalescent theory to estimate short- and long-term directional gene flow among subpopulations for two reptiles that occur in Canada as peripheral populations that are geographically disjunct from the core of their respective species’ ranges: the black ratsnake and the Blanding’s turtle. Estimates of directional gene flow were used to examine population connectivity and potential genetic source-sink dynamics. For both species, our estimates of directional short- and long-term gene flow were consistently lower than estimates inferred previously from F _ST measures. Short- and long-term gene flow estimates were discordant in both species, suggesting that population dynamics have varied temporally in both species. These estimates of directional gene flow were used to identify specific subpopulations in both species that may be of high conservation value because they are net exporters of individuals to other subpopulations. Overall, our results show that the use of more sophisticated methods to evaluate population genetic data can provide valuable information for the conservation of species at risk, including bidirectional estimates of subpopulation connectivity that rely on fewer assumptions than more traditional analyses. Such information can be used by conservation practitioners to better understand the geographic scope required to maintain a functional metapopulation, determine which habitat corridors within a working landscape may be most important to maintain connectivity among subpopulations, and to prioritize subpopulations with respect to their potential to act as genetic sources within the metapopulation.     

Cajal 间质细胞在中华鳖肠道的分布差异和超微特征

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