Search

BackgroundTranscriptomic data has demonstrated utility to advance the study of physiological diversity and organisms' responses to environmental stressors. However, a lack of genomic resources and challenges associated with collecting high-quality RNA can limit its application for many wild populations. Minimally invasive blood sampling combined with de novo transcriptomic approaches has great potential to alleviate these barriers. Here, we advance these goals for marine turtles by generating high quality de novo blood transcriptome assemblies to characterize functional diversity and compare global transcriptional profiles between tissues, species, and foraging aggregations.ResultsWe generated high quality blood transcriptome assemblies for hawksbill (Eretmochelys imbricata), loggerhead (Caretta caretta), green (Chelonia mydas), and leatherback (Dermochelys coriacea) turtles. The functional diversity in assembled blood transcriptomes was comparable to those from more traditionally sampled tissues. A total of 31.3% of orthogroups identified were present in all four species, representing a core set of conserved genes expressed in blood and shared across marine turtle species. We observed strong species-specific expression of these genes, as well as distinct transcriptomic profiles between green turtle foraging aggregations that inhabit areas of greater or lesser anthropogenic disturbance.ConclusionsObtaining global gene expression data through non-lethal, minimally invasive sampling can greatly expand the applications of RNA-sequencing in protected long-lived species such as marine turtles. The distinct differences in gene expression signatures between species and foraging aggregations provide insight into the functional genomics underlying the diversity in this ancient vertebrate lineage. The transcriptomic resources generated here can be used in further studies examining the evolutionary ecology and anthropogenic impacts on marine turtles.

Spatiotemporal predictions of bycatch (i.e., catch of nontargeted species) have shown promise as dynamic ocean management tools for reducing bycatch. However, which spatiotemporal model framework to use for generating these predictions is unclear. We evaluated a relatively new method, Gaussian Markov random fields (GMRFs), with two other frameworks, generalized additive models (GAMs) and random forests. We fit geostatistical delta-models to fisheries observer bycatch data for six species with a broad range of movement patterns (e.g., highly migratory sea turtles versus sedentary rockfish) and bycatch rates (percentage of observations with nonzero catch, 0.3%-96.2%). Random forests had better interpolation performance than the GMRF and GAM models for all six species, but random forests performance was more sensitive when predicting data at the edge of the fishery (i.e., spatial extrapolation). Using random forests to identify and remove the 5% highest bycatch risk fishing events reduced the bycatch-to-target species catch ratio by 34% on average. All models considerably reduced the bycatch-to-target ratio, demonstrating the clear potential of species distribution models to support spatial fishery management. Les predictions spatiotemporelles de prises accessoires (c.-a-d. prises d'especes non visees) sont prometteuses comme outils de gestion dynamique des oceans pour reduire ces prises. Cependant, la nature du cadre de modelisation spatiotemporelle a utiliser pour produire ces predictions n'est pas bien etablie. Nous avons evalue une methode relativement nouvelle, les champs aleatoires de Markov gaussiens (CAMG), et deux autres cadres, les modeles additifs generalises (MAG) et les forets aleatoires. Nous avons cale des modeles delta geostatistiques a des donnees d'observateurs des peches sur les prises accessoires representatives d'un vaste eventail de motifs de deplacement (p. ex. de tortues de mer tres migratrices a des sebastes sedentaires) et de frequences de prises accessoires (pourcentages d'observations de prise non nulle de 0,3 % a 96,2 %). Les forets aleatoires donnent de meilleures interpolations que les modeles CAMG et MAG pour les six especes, mais la performance des forets aleatoires est plus sensible quand il s'agit de predire des donnees a la limite de la peche (c.-a-d. pour l'extrapolation spatiale). L'utilisation de forets aleatoires pour cerner et retirer les 5 % des evenements de peche qui presentent le risque le plus eleve de prises accessoires reduit le rapport des prises accessoires et des prises de l'espece visee de 34 % en moyenne. Tous les modeles reduisent considerablement ce rapport, ce qui demontre clairement le potentiel des modeles de distribution d'especes comme outil pour appuyer la gestion spatiale des peches. [Traduit par la Redaction], Introduction Bycatch--catch of nontargeted species--occurs in nearly every commercial and recreational fishery and in many cases is a serious environmental and economic problem (Alverson et al. 1994; Davies et al. [...]

Green sea turtles, Chelonia mydas, are known to inhabit populated and often urbanized areas. To understand turtle habitat use and behavior within these unique habitats, seven juvenile green turtles were fitted with acoustic transmitters (September 2012-August 2014), of which two transmitters included an accelerometer (AP transmitter). One individual fitted with an AP transmitter was tracked using a passive acoustic array in an urbanized river, the San Gabriel River, Long Beach, CA (33[degrees]45' N, 118[degrees]05' W). Three additional turtles in this river and three turtles (one with AP transmitter) in a restored estuary (33[degrees]44' N, 118[degrees]03' W) in southern California were actively tracked for two nonconsecutive 24-h periods. Those fitted with AP transmitters indicated that turtles were less active at night (0.58 [+ or -] 0.56 m/[s.sup.2] and 0.50 [+ or -] 0.63 m/[s.sup.2]) than during the day (0.86 [+ or -] 0.63 m/[s.sup.2] and 0.78 [+ or -] 0.60 m/[s.sup.2]) at both sites. Activity data and corresponding movements of the actively tracked turtle fitted with the AP transmitter were used to infer resting periods for other tracked individuals. Turtles rested near bridge pilings and runoff outflows in the river to potentially shelter from tidal flow. Turtles used significantly larger daily areas in the urbanized river (0.046 [+ or -] 0.023 [km.sup.2]) where resources may be patchier and less abundant, compared to turtles in the estuary (0.024 [+ or -] 0.012 [km.sup.2]) where large, dense eelgrass beds are present. Based on the habitat use and behaviors of green sea turtles, it appears that some green sea turtles are able to make use of both highly developed and restored habitats and likely benefit from certain aspects of development., Green sea turtles, Chelonia mydas, have been listed and protected in the United States under the Endangered Species Act (ESA) since 1978 (FWS andNMFS, 80 FR 15271). Through decades of [...]

Somatic growth rates of green turtles (Cheloniamydas) are affected by foraging success and influence their survival and reproduction. Gorgona National Park (GNP) in the Colombian Pacific (2°58'03'N, 78°10'49'W) is an insular foraging site that offers a unique opportunity to study the black (occurring only in the eastern Pacific) and yellow (with western Pacific nesting beach origins) morphotypes of green turtles during their juvenile phase. A total of 995 turtles were captured and marked between October 2003 and December 2012. Recapture rates were low (20 black morphotype and 13 yellow morphotype turtles) but suggested that at least some turtles remain in the area for extended periods (>5 years). Mean growth rate was slightly higher for black morphotype (mean 0.92 ± 0.24 cm y.sup.-1) than yellow morphotype turtles (mean 0.74 ± 0.26 cm y.sup.-1), and both morphotypes displayed a non-monotonic growth pattern. Black morphotype turtles grew faster at intermediate sizes, similar to black turtles at other locations in the eastern Pacific, whereas yellow morphotype turtles had slowest growth at intermediate sizes. Our data underscore the importance of GNP as a foraging habitat for C.mydas individuals from distinct nesting populations and indicate that these morphotypes have different growth patterns while residing at the same foraging site., Author(s): Laura Sampson [sup.1] , Alan Giraldo [sup.1] , Luis Fernando Payán [sup.2] , Diego F. Amorocho [sup.3] , Tomoharu Eguchi [sup.4] , Jeffrey A. Seminoff [sup.4] Author Affiliations: (Aff1) [...]

The South Pacific subpopulation of the loggerhead turtle Caretta caretta is categorized as Critically Endangered on the IUCN Red List because of significant population declines. Five Queensland beaches support high-density nesting of this subpopulation, but egg and hatchling survival are low at some beaches because of feral and native terrestrial predators. We quantified predation of loggerhead turtle eggs by two species of goanna, Varanus panoptes and Varanus varius, at Wreck Rock beach, one of the turtle's major nesting beaches. In addition, we conducted an experiment to determine the efficacy of a nest protection device. Predation rates at Wreck Rock beach were 15.2% for treatment and 45.8% for non-treatment clutches during the 2013–2014 nesting season. A higher probability of predation (64%) was predicted for the northern beach. Although nests were only partially predated (16.4% of the total number of eggs), nest loss to predators and beach erosion (caused by a cyclone) was 91.7%. If left unmanaged, the cumulative impact of predation and other threats, including those exacerbated by climate change, can cause unsustainable loss of loggerhead turtle nests. This study provides one of the first quantitative data sets on rates of loggerhead turtle clutch predation in the South Pacific. It enhances our understanding of goanna predation impacts and identifies an efficient predator exclusion device for mitigating the effects of terrestrial predators at Wreck Rock beach, and for protecting marine turtle nests across northern Australia and globally. [ABSTRACT FROM AUTHOR]