Fine-scale geographic difference of the endangered Big-headed Turtle (Platysternon megacephalum) fecal microbiota, and comparison with the syntopic Beale's Eyed Turtle (Sacalia bealei).

BACKGROUND: Studies have elucidated the importance of gut microbiota for an organism, but we are still learning about the important influencing factors. Several factors have been identified in helping shape the microbiome of a host, and in this study we focus on two factors-geography and host. We characterize the fecal microbiota of the Big-headed Turtle (Platysternon megacephalum) and compare across a relatively fine geographic scale (three populations within an 8-km radius) and between two syntopic hosts (P. megacephalum and Sacalia bealei). Both species are endangered, which limits the number of samples we include in the study. Despite this limitation, these data serve as baseline data for healthy, wild fecal microbiotas of two endangered turtle species to aid in conservation management. RESULTS: For geography, the beta diversity of fecal microbiota differed between the most distant sites. The genus Citrobacter significantly differs between sites, which may indicate a difference in food availability, environmental microbiota, or both. Also, we identify the common core microbiome for Platysternon across Hong Kong as the shared taxa across the three sites. Additionally, beta diversity differs between host species. Since the two species are from the same site and encounter the same environmental microbiota, we infer that there is a host effect on the fecal microbiota, such as diet or the recruitment of host-adapted bacteria. Lastly, functional analyses found metabolism pathways (KEGG level 1) to be the most common, and pathways (KEGG level 3) to be statistically significant between sites, but statistically indistinguishable between species at the same site. CONCLUSIONS: We find that fecal microbiota can significantly differ at a fine geographic scale and between syntopic hosts. Also, the function of fecal microbiota seems to be strongly affected by geographic site, rather than species. This study characterizes the identity and function of the fecal microbiota of two endangered turtle species, from what is likely their last remaining wild populations. These data of healthy, wild fecal microbiota will serve as a baseline for comparison and contribute to the conservation of these two endangered species.

Effects of postovipositional hypoxia and hyperoxia on leatherback turtle reproductive success and hatchling performance.

Leatherback egg clutches typically experience lower hatching success (~50%) than those of other sea turtle species (>70%). The majority of embryonic death (>50%) occurs at early stages of development, possibly because embryos fail to break preovipositional embryonic arrest after oviposition. The embryonic arrest is maintained by hypoxia in the oviduct and following oviposition increased availability of oxygen is the trigger that breaks arrest in all turtle species studied to date. We conducted an ex situ incubator experiment and an in situ hatchery experiment to examine the influence of oxygen availability on hatching success and hatchling traits in leatherbacks. After oviposition, eggs (n = 1005) were incubated in either normoxia (21% O2 ), hyperoxia (32%-42% O2 ) for 5 days, or hypoxia (1% O2 ) for 3 or 5 days. As with other turtles, hypoxic incubation maintained embryos in arrest, equivalent to the time spent in hypoxia. However, extending arrest for 5 days resulted in greater early-stage death and a significant decrease in hatching success (4% 5-day hypoxia vs. 72% normoxia). Eggs placed in incubators had greater hatching success than those placed into hatchery nests (67% vs. 47%, respectively). We found no impact of hyperoxia on the stage of embryonic death, hatching success, hatchling phenotype, exercise performance, or early dispersal. Our findings indicate that delayed nesting and the subsequent extension of embryonic arrest may negatively impact embryonic development and therefore the reproductive success of leatherbacks. They also indicate that incubation under hyperoxic conditions is unlikely to be a useful method to improve hatching success in this species.

Habitat Selection and Home Range of Reeves' Turtle (Mauremys reevesii) in Qichun County, Hubei Province, China.

Habitat selection and range are crucial factors in understanding the life history of species. We tracked 23 adult wild Reeves' turtles (Mauremys reevesii) from August 2021 to August 2022 in Qichun County, Hubei Province, China, to study their habitat selection, home range, and the characteristics of chosen habitats. Significant differences were observed in aquatic habitats, regarding shelter cover (Z = -6.032, p < 0.001), shelter height (Z = -6.783, p < 0.001), depth of water (Z = -2.009, p = 0.045), and distance from the edge (Z = -4.288, p < 0.001), between selected and random habitats. In terrestrial habitats, significant differences were observed in canopy cover (Z = -2.100, p = 0.036), herbage cover (Z = -2.347, p = 0.019), distance from the field edge (Z = -2.724, p = 0.006), dead grass cover (Z = -2.921, p = 0.003), and dead grass thickness (t = 3.735, df = 17, p = 0.002) between the selected and random habitats. The mean home range area observed for this turtle population was 14.34 ± 4.29 ha, the mean core home range was 2.91 ± 2.28 ha, and the mean line home range was 670.23 ± 119.62 m. This study provides valuable information on this endangered species, providing a foundation for the development of conservation plans.

Spatial variation of plastic debris on important turtle nesting beaches of the remote Chagos Archipelago, Indian Ocean.

We report Anthropogenic Marine Debris (AMD) in Chagos Archipelago in the Indian Ocean, globally amongst the most isolated island groups. AMD on 14 island beaches in five atolls were surveyed in 2019 using two techniques: Marine Debris Tracker (MDT) along littoral vegetation and photoquadrats in open beach. Over 60 % of AMD in both beach zones was composed of plastics, especially bottles and fragments (mean = 44.9 %, 27.2 %, range = 16.5-73.2 %, 4.8-55.9 % respectively in vegetation; mean = 28.7 %, 31.5 %, range = 17.7-40.7 %, 11.6-60.0 % respectively in open beach). The density of plastic debris in littoral vegetation (MDT data: 1995 bottles, 3328 fragments per 100 m2) was 10-fold greater than in open beach (photoquadrat data: 184 bottles, 106 fragments per 100 m2). Significant latitudinal variation in vegetation AMD occurred (8-fold greater in southern atolls, p = 0.006). AMD varied within island zones: most debris observed on oceanside beaches (oceanside vs lagoon, W = 365, p < 0.001; ocean vs island tip, W = 107, p = 0.034). Standardisation of surveys using the open-source MDT App is recommended. Debris accumulation hotspots overlapped with sea turtle nesting habitat, guiding future beach clean-up prioritisation.

Nesting trends of olive ridley sea turtles Lepidochelys olivacea (Testudinata: Cheloniidae) on two beaches in Northwestern Mexico after 30 and 40 years of conservation / Tendencias de anidación de la tortuga golfina Lepidochelys olivacea (Testudinata: Cheloniidae) en dos playas del noroeste de México después de 30 y 40 años de conservación

Abstract Introduction: Although olive ridley sea turtle (Lepidochelys olivacea) are the most abundant sea turtles in the world, quantitative information is scarce and unevenly distributed among regions. There are many management and conservation programs for this species, and assessments are necessary to identify nesting trends and effectively manage current conservation programs. PROTORMAR-UAS is a Research and Conservation program for the olive ridley turtle created by the Autonomous University of Sinaloa, Mexico. The program utilizes two biological stations: Santuario Playa Ceuta (SPC) and Playa Caimanero (PC). Objective: To evaluate the nesting trend of olive ridley turtles on two beaches in Northwestern Mexico and to predict prospective nesting trends for the next 30 years. Methods: Using annual nesting data collected over 40 years at SPC (1976-2016) and 30 years at PC (1986-2016), we evaluated nesting trends, hatching success, predation and poaching of olive ridley turtles on the two beaches in Northwestern Mexico. Then, prospective nesting estimates for the next 30 years were calculated predictive time series model. Results: A positive and significant correlation was identified between the number of annual nests and time for both beaches (rho = 0.850, P ≤ 0.01 for SPC; rho = 0.677, P ≤ 0.01 for PC); the average hatching success rates were 65.09 at SPC and 60.72 % at PC. The predictive time-series model indicated that the numbers of nests will continue to increase through 2045, increasing three-fold at SPC and six-fold at PC with respect to the last year of monitoring. Conclusions: There was a clear positive trend in the number of olive ridley sea turtle nests at both sites, which is consistent with trends found in other recent studies from the region. Therefore, we suggest that PC be designated a legally protected nesting area since it is located within the latitudinal limits of olive ridley nesting and given the need for resources for camp operation considering increased nesting and current problems with predation and poaching. Because in Mexico operating a nesting beach without any protection status implies not having a budget for its management.

Resumen Introducción: A pesar de que las tortugas golfinas (Lepidochelys olivacea) son las tortugas marinas más abundantes del mundo, su información cuantitativa disponible es escasa y se encuentra distribuida de manera desigual entre regiones. Existen muchos programas de manejo y conservación para esta especie, y sus evaluaciones son necesarias para identificar tendencias de anidación y poder manejar de manera efectiva los programas de conservación actuales. PROTORMAR-UAS es un programa de Investigación y Conservación de la tortuga golfina creado por la Universidad Autónoma de Sinaloa, México. El Programa cuenta con dos estaciones biológicas: Santuario de Playa Ceuta (SPC) y Playa Caimanero (PC). Objetivo: Evaluar la tendencia de anidación de la tortuga golfina en dos playas del noroeste de México y predecir las tendencias prospectivas de anidación para los próximos 30 años. Métodos: A partir de los datos de registros anuales de anidación de 40 años para SPC (1976-2016) y 30 años para PC (1986-2016), evaluamos las tendencias de anidación, el éxito de la eclosión y los problemas de depredación y saqueo de nidos de la tortuga golfina en las dos playas del noroeste de México. Posteriormente, se calcularon las estimaciones prospectivas de anidación para los próximos 30 años usando un modelo predictivo de series de tiempo. Resultados: Se identificó una correlación positiva y significativa entre el registro anual de nidos y el tiempo de estudio para ambas playas (rho = 0.850, P ≤ 0.01 para SPC; rho = 0.677 y P ≤ 0.01 para PC); así como el éxito de eclosión promedio de 65.09 para SPC y de 60.72 % para PC. El modelo predictivo de series de tiempo indicó que las anidaciones continuarán aumentando para el 2045, tres veces para SPC y seis para PC, con respecto al último año de monitoreo. Conclusiones: Hay una clara tendencia positiva de anidación de la tortuga golfina en ambos sitios, lo cual es consistente con la tendencia observada en otros estudios recientes de la región. Por lo tanto, sugerimos incluir a PC como un área de anidación legalmente protegida, la cual se ubica en los límites latitudinales de anidación de la tortuga golfina, dada la necesidad de contar con recursos disponibles para la operación del campamento ante el aumento de anidaciones y de problemas de depredación y saqueo. Porque en México operar una playa de anidación sin ningún estatus de protección implica no tener presupuesto para su manejo.

Community based actions save Yellow-spotted river turtle (Podocnemis unifilis) eggs and hatchlings flooded by rapid river level rises.

The conservation and recovery of increasingly threatened tropical freshwater turtle populations depends on effective management plans and actions. Here we show that community-based actions saved Yellow-spotted river turtle (Podocnemis unifilis) eggs submerged by unseasonal flooding and ensured the release of hatchlings. We recovered 926 eggs and 65 premature hatchlings from 74 submerged nests at 16 flooded nesting areas along 75 km of waterways. The rescued eggs were transferred to a rearing center and incubated. Hatchlings emerged from eggs that had remained underwater for up to two days. Hatchlings were maintained in 250-500 L nursery tanks until yolk sac scars had closed. Healthy hatchlings were then immediately released around the original nesting areas. We released 599 hatchlings (60.4%) from 991 submerged eggs and hatchlings. Egg survival (61.7% (571/926)) was substantially less than hatchling survival (94.2% (599/636)) but within the expected range of values reported for this species. These findings suggest that Yellow-spotted river turtle eggs and embryos are resistant to short-term submersion, which could help explain the widespread distribution of this species across highly seasonal Amazonian rivers. Management plans should take the possible survival of submerged eggs into consideration as part of species conservation and recovery actions.

Environmental and anthropogenic factors affecting nesting site selection by sea turtles.

Understanding the environmental and anthropogenic factors that affect nesting site selection by sea turtles is key to maintaining priority conservation areas. The species Lepidochelys olivacea, Caretta caretta, and Eretmochelys imbricata nest annually on the island of Comandatuba (Una, northeastern Brazil), where this survey was conducted. We evaluated the temporal and spatial distribution of nests during the seasons 2008/2009 to 2014/2015 and 2017/2018. In the last season, we further examined the environmental and anthropogenic factors that influence different nesting performances. We selected six sample areas with different nesting events (high, medium, and low), and recorded the following characteristics: beach slope, sediment grain size, vegetation richness, type of dune, anthropization, and final nest condition. A significant occurrence of nesting was observed in November and December . The spatial distribution of the nests varied over the seasons, with a greater tendency to nest in the south of the island. Higher frequency of anthropization and low slope of the beach were significant factors for areas with a smaller number of nests. Predation of turtle nests may be associated with areas of greater anthropization. Our findings have implications for the conservation and monitoring of nesting sites during reproduction seasons and provide further insight into the nesting dynamics of marginal sea turtle populations.

Reproductive ecology of the endangered Beal's-eyed turtle, Sacalia bealei.

The Beal's-eyed turtle (Sacalia bealei) is endemic to southeastern China and endangered due to poaching and habitat loss. Knowledge of S. bealei ecology is lacking and this study provides baseline information of its reproduction in a natural environment. We studied the reproductive ecology of S. bealei using X-ray, spool-and-line tracking, and direct observation. Six nesting females were successfully tracked and their nesting behaviors are documented in detail. Females produced a mean clutch size of 2.2 eggs (range 1-3). The hard-shelled eggs were ellipsoidal with a mean length of 45.50 mm, a mean width of 23.20 mm, and mean weight of 14.8 g. The relative clutch mass was 9.47%, while the relative egg mass was 4.60%. The mean incubation period was 94.7 days with a mean nest temperature of 25.08 °C. Hatchlings had a mean weight of 9.7 g, carapace length of 40.1 mm, carapace width of 33.3 mm, carapace height of 17.4 mm, plastron length of 31.6 mm, and plastron width of 25.4 mm. The results of this study provide important information to inform conservation plans and ex-situ breeding for this endangered species.

Community involvement works where enforcement fails: conservation success through community-based management of Amazon river turtle nests.

Law enforcement is widely regarded as a cornerstone to effective natural resource management. Practical guidelines for the optimal use of enforcement measures are lacking particularly in areas protected under sustainable and/or mixed use management regimes and where legal institution are weak. Focusing on the yellow-spotted river turtles (Podocnemis unifilis) along 33 km of river that runs between two sustainable-use reserves in the Brazilian Amazon as an illustrative example, we show that two years of patrols to enforce lawful protection regulations had no effect on nest harvesting. In contrast, during one year when community-based management approaches were enacted harvest levels dropped nearly threefold to a rate (26%) that is likely sufficient for river turtle population recovery. Our findings support previous studies that show how community participation, if appropriately implemented, can facilitate effective natural resource management where law enforcement is limited or ineffective.

Molecular phylogeny and divergence of the map turtles (Emydidae: Graptemys).

The map turtles (genus Graptemys) comprise a morphologically diverse clade that forms a major component of the southeastern US hotspot of chelonian diversity. Map turtles have experienced both recent and rapid diversification resulting in long-standing uncertainty regarding species boundaries and phylogenetic relationships within the genus as well as timing of their divergence. We present a phylogeny for the group that includes geographically representative sampling for all described species and subspecies. We make use of an empirical prior on rates of molecular evolution to estimate divergence times with a molecular clock under a coalescent framework. Together, the phylogeny and divergence time estimates suggest that diversification has been both more recent and more rapid than has so far been suspected. We provide a well-supported evolutionary framework for Graptemys that is necessary for understanding map turtle diversity, biogeography, and for conservation of this threatened clade of turtles.

Integrating science education and marine conservation through collaborative partnerships.

The Georgia Sea Turtle Center has a mission of conservation based rehabilitation, research, and education. Marine debris is a serious threat to marine species. In an effort to educate local students, the GSTC obtained a grant to provide educational opportunities to local third graders. Third and fourth grade classes in Glynn County, Georgia were offered a Garbage in the Water program and 964 students were reached. After programming, students showed a statistically significant (p<.0001) increase in test scores between the pre and posttests. This success led to repeat funding for additional programming for first grades as well as a formalized relationship with the Glynn County School District. As part of this relationship the Georgia Sea Turtle Center is now the official field trip location for all third grades in the district.

Perceptions of fishers to sea turtle bycatch, illegal capture and consumption in the San Ignacio-Navachiste-Macapule lagoon complex, Gulf of California, Mexico.

In this study, 10% of all registered fishermen in the coastal towns of Navachiste in Sinaloa, in northwestern Mexico, answered a survey designed to collect data on their perceptions of the following topics: the impact of turtle meat consumption; human health; bycatch; illegal turtle fishing; the illegal sea turtle market; the local economy; pollution; environmental education; the success of protective legislation; and sea turtle-based ecotourism. Perceptions were analyzed using the fuzzy logic method through classification into 5 fuzzy membership sets: VL, very low; L, low; M, moderate; H, high; VH, very high. The 9 topics generated decision areas upon applying fuzzy inference that revealed the membership level of the answers in each fuzzy set. The economic potential of sea turtle-based ecotourism and the economic profitability of the illegal turtle meat market were perceived as VL. Conservation legislation was perceived as H, although inefficiently applied due to corruption. Ecotourism and impacts on sea turtles were perceived as VL, because they were deemed unprofitable activities at the individual and community levels. Environmental education was perceived as L, because it centers on nesting, hatching and releasing turtles and is directed at elementary and middle-school students. While fishers perceive a serious negative impact of fishing activities on sea turtles in the San Ignacio-Navachiste-Macapule area, they do not see themselves individually as part of the problem. Achieving sea turtle conservation in this region requires: suitable ecotourism infrastructure, government investments in promotion, and studies to estimate the minimum number of tourists needed to assure profitability.

Caracterización espacio-temporal del hábitat y presencia de Dermatemys mawii (Testudines: Dermatemydidae) en la cuenca del Grijalva-Usumacinta, Tabasco, México

Presence and spatio-temporal habitat characterization of Dermatemys mawii (Testudines: Dermatemydidae) in the Grijalva-Usumacinta watershed, Tabasco, Mexico. The Central American River Turtle (Dermatemys mawii) is an endangered species that has been poorly studied. There are no reports on their population status, habitat condition, and the species distribution area is still unknown. This study analyzes the seasonal and spatial variations of their habitat and the presence/absence of D. mawii in three rivers within the Pantanos de Centla Biosphere Reserve (Tabasco, Mexico). For habitat characterization, natural segmentation of rivers was used and three sites per segment were identified, 9 in each rivers (Grijalva and Usumacinta) and 6 in Tabasquillo. Additionally, the evaluation of 11 environmental variables such as water hydrological, physicochemical characteristics and riparian and hydrophytic vegetation were carried out during two different seasons (dry and rainy). The presence/absence of species was assessed with eight fike nets that were set per segment, with a capture effort of 384 hours per trap. The capture per unit effort (CPUE) was used as an indicator of relative abundance. The results indicated spatio-temporal variations in habitat characteristics and the presence of environmental gradients. The principal components analysis (PCA) applied allowed us to determine that the first three components explained 67.8% of the environmental variability. The species presence was confirmed in all rivers, however significant differences exists in their relative abundance: the highest was registered in the Tabasquillo River where the species was present in both seasons and in all segments. Of the 11 environmental variables analyzed, the gradient, shelter and depth were the most indicative of species presence. The obtained results evidenced the importance of riparian vegetation as habitat for Dermatemys. This represents the first approach towards an action plan for a species and its habitat protection within the Pantanos de Centla Biosphere Reserve. Rev. Biol. Trop. 58 (4): 1247-1260. Epub 2010 December 01.

La tortuga centroamericana (Dermatemys mawii) es una especie en peligro de extinción pobremente estudiada. En el presente trabajo se analizaron las variaciones estacionales y espaciales del hábitat y se relacionaron con la presencia/ausencia de D. mawii en tres ríos de la Reserva de la Biosfera Pantanos de Centla (Tabasco, México). Para caracterizar el hábitat se evaluaron 11 variables (hidrológicas, fisicoquímicas del agua y de la vegetación) en dos temporadas (seca y lluviosa). Para determinar la presencia/ ausencia de la especie se colocaron 8 trampas de desvío acuáticas, empleando la captura por unidad de esfuerzo (CPUE) como indicador de la abundancia relativa. Los resultados indicaron variaciones espacio-temporales. El análisis de componentes principales (ACP) permitió determinar la variabilidad ambiental. La presencia de la especie se confirmó en los tres ríos, sin embargo la mayor abundancia relativa se registró en el Río Tabasquillo. Cuatro variables tuvieron el mayor peso como variables predictoras de la presencia de la especie. Con los resultados obtenidos, es evidente la importancia que tiene el ambiente ribereño como hábitat para Dermatemys, asimismo es posible hacer el primer acercamiento a un plan de acción para la protección de la especie y su hábitat en esta reserva.