Comparison of the blood biochemical values of foraging and nesting Olive Ridley turtles (Lepidochelys olivacea) from Sinaloa, Mexico.

Our study aimed to establish reference values for nesting females and compare them with those previously reported to understand olive ridley turtles' health status and contribute to long-term health assessment and monitoring in foraging and nesting areas from the state of Sinaloa, Mexico. In August and September 2018, morphometric data and biochemical profiles were collected from 33 nesting olive ridley turtles from Ceuta Beach Sanctuary (CBS) and 14 foraging female turtles captured at the foraging site, Navachiste Marine Area (NMA). Nesting turtles sampled had greater CCL (65.86 ± 1.70 cm) than those from the foraging area (61.54 ± 1.22) (p < 0.05). Regarding biochemical profiles, post-nesting turtles had higher packed cell volume (PCV), albumin, blood urea nitrogen (BUN), cholesterol, triglycerides, and calcium than turtles from the foraging area (p < 0.05). Phosphorus levels were higher in foraging turtles than in nesting turtles (p = 0.001), while the remaining parameters showed no significant differences. The present study describes for the first time the blood biochemical values of nesting turtles from the Ceuta Beach Sanctuary in southern Sinaloa, Mexico, similar to those of foraging turtles from the north of the state. The significant differences observed between the two analysis groups may be due to the energy reserves and reproductive and nesting activity of the nesting turtles, so the blood biochemistry values described in this study can be used as a standard reference blood value for the olive ridley turtle population of Sinaloa, Mexico.

Trace elements concentration in blood of nesting Kemp's Ridley turtles (Lepidochelys kempii) at Rancho Nuevo sanctuary, Tamaulipas, Mexico.

The concentrations of trace elements including As, Zn, Cu, Se, Pb, Hg and Cd, were determined in the blood of nesting Kemp's ridley turtles (Lepidochelys kempii) at Rancho Nuevo sanctuary, Tamaulipas, Mexico during 2018-2020. The sequential concentrations analyzed were Zn> Se> Cu> As> Pb; while Cd and Hg concentrations were below the limits of detection (0.01 µg g-1). No significant differences were observed between the concentrations of trace elements (p> 0.05) by year, except Se levels, possibly resulting from recorded seasonal differences in turtle size. No relationships among turtle size vs elements concentration were observed. In conclusion, essential and toxic trace elements concentrations in the blood of nesting Kemp's ridley turtles may be a reflex of the ecosystem in which the turtles develop, that is, with low bioavailability of elements observed in the trophic webs in the Gulf of Mexico.

ISOLATION, CHARACTERIZATION, AND ANTIMICROBIAL SUSCEPTIBILITY OF BACTERIA ISOLATED FROM SEA LION (ZALOPHUS CALIFORNIANUS) PUPS IN NORTHWESTERN MEXICO.

Bacterial infections have been documented in marine mammals for decades, and some are considered emerging pathogens with zoonotic potential. The aerobic oral (n=16) and rectal (n=17) bacterial microbiota and their antimicrobial resistance were characterized for 17 apparently healthy California sea lion pups (Zalophus californianus) captured with a hoop net in Farallon Island, Sinaloa, Mexico, in 2016. Bacteriologic cultures, Analytical Profile Index, and PCR were used to identify bacterial species. The Escherichia coli phylogenetic groups were identified by PCR, Salmonella serotypes were identified, and resistance to antibiotics was evaluated. Overall, 39 bacterial species were isolated, including E. coli and Salmonella spp. (35.9% each) and Pseudomonas aeruginosa (28.2%). For E. coli, UNKNOWN phylogroup was the most prevalent (57.7%), followed by the A phylogroup (37.1%). Most Salmonella serotypes were identified as Newport (92.8%); serotype Saintpaul was also identified (7.2%). Sea lions with bacterial co-colonization included 24.2%, from which two bacterial species were isolated, and 3% with three species. Overall, 59% of bacteria were resistant to at least one antibiotic tested, and 25.6% were extensively drug resistant. Bacteria were highly resistant to ampicillin and cefotaxime. This study demonstrates the importance of characterizing the microbiome of sea lions, and the potential effect of pathogens with antimicrobial resistance on wildlife conservation and public health.

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.

Natal foraging philopatry in eastern Pacific hawksbill turtles.

The complex processes involved with animal migration have long been a subject of biological interest, and broad-scale movement patterns of many marine turtle populations still remain unresolved. While it is widely accepted that once marine turtles reach sexual maturity they home to natal areas for nesting or reproduction, the role of philopatry to natal areas during other life stages has received less scrutiny, despite widespread evidence across the taxa. Here we report on genetic research that indicates that juvenile hawksbill turtles (Eretmochelys imbricata) in the eastern Pacific Ocean use foraging grounds in the region of their natal beaches, a pattern we term natal foraging philopatry. Our findings confirm that traditional views of natal homing solely for reproduction are incomplete and that many marine turtle species exhibit philopatry to natal areas to forage. Our results have important implications for life-history research and conservation of marine turtles and may extend to other wide-ranging marine vertebrates that demonstrate natal philopatry.

Hawksbill turtle terra incognita: conservation genetics of eastern Pacific rookeries.

Prior to 2008 and the discovery of several important hawksbill turtle (Eretmochelys imbricata) nesting colonies in the EP (Eastern Pacific), the species was considered virtually absent from the region. Research since that time has yielded new insights into EP hawksbills, salient among them being the use of mangrove estuaries for nesting. These recent revelations have raised interest in the genetic characterization of hawksbills in the EP, studies of which have remained lacking to date. Between 2008 and 2014, we collected tissue samples from 269 nesting hawksbills at nine rookeries across the EP and used mitochondrial DNA sequences (766 bp) to generate the first genetic characterization of rookeries in the region. Our results inform genetic diversity, population differentiation, and phylogeography of the species. Hawksbills in the EP demonstrate low genetic diversity: We identified a total of only seven haplotypes across the region, including five new and two previously identified nesting haplotypes (pooled frequencies of 58.4% and 41.6%, respectively), the former only evident in Central American rookeries. Despite low genetic diversity, we found strong stock structure between the four principal rookeries, suggesting the existence of multiple populations and warranting their recognition as distinct management units. Furthermore, haplotypes EiIP106 and EiIP108 are unique to hawksbills that nest in mangrove estuaries, a behavior found only in hawksbills along Pacific Central America. The detected genetic differentiation supports the existence of a novel mangrove estuary "reproductive ecotype" that may warrant additional conservation attention. From a phylogeographic perspective, our research indicates hawksbills colonized the EP via the Indo-Pacific, and do not represent relict populations isolated from the Atlantic by the rising of the Panama Isthmus. Low overall genetic diversity in the EP is likely the combined result of few rookeries, extremely small reproductive populations and evolutionarily recent colonization events. Additional research with larger sample sizes and variable markers will help further genetic understanding of hawksbill turtles in the EP.

Multinational tagging efforts illustrate regional scale of distribution and threats for east pacific green turtles (Chelonia mydas agassizii).

To further describe movement patterns and distribution of East Pacific green turtles (Chelonia mydas agassizii) and to determine threat levels for this species within the Eastern Pacific. In order to do this we combined published data from existing flipper tagging and early satellite tracking studies with data from an additional 12 satellite tracked green turtles (1996-2006). Three of these were tracked from their foraging grounds in the Gulf of California along the east coast of the Baja California peninsula to their breeding grounds in Michoacán (1337-2928 km). In addition, three post-nesting females were satellite tracked from Colola beach, Michoacán to their foraging grounds in southern Mexico and Central America (941.3-3020 km). A further six turtles were tracked in the Gulf of California within their foraging grounds giving insights into the scale of ranging behaviour. Turtles undertaking long-distance migrations showed a tendency to follow the coastline. Turtles tracked within foraging grounds showed that foraging individuals typically ranged up to 691.6 km (maximum) from release site location. Additionally, we carried out threat analysis (using the cumulative global human impact in the Eastern Pacific) clustering pre-existing satellite tracking studies from Galapagos, Costa Rica, and data obtained from this study; this indicated that turtles foraging and nesting in Central American waters are subject to the highest anthropogenic impact. Considering that turtles from all three rookeries were found to migrate towards Central America, it is highly important to implement conservation plans in Central American coastal areas to ensure the survival of the remaining green turtles in the Eastern Pacific. Finally, by combining satellite tracking data from this and previous studies, and data of tag returns we created the best available distributional patterns for this particular sea turtle species, which emphasized that conservation measures in key areas may have positive consequences on a regional scale.