The worldwide population of the leatherback turtle (Dermochelys coriacea) encompasses seven subpopulations among the Pacific, Atlantic and Indian Oceans. It has experienced declines across parts of its distribution, with the subpopulation of the South-west Atlantic listed as critically endangered by the IUCN Red List. The main threats to this subpopulation include its interaction with fisheries, coastal development, pollution and climate change. In this study, we sequenced mitochondrial DNA from 52 leatherback turtles in Brazil and combined these with published data from other Atlantic Ocean rookeries. The haplotype diversities of the Atlantic population rookeries ranged from 0.112 to 0.533 and are not directly proportional to current rookery sizes. The Brazilian rookery, despite recording low nest numbers per year, had the second-highest haplotype diversity among all Atlantic rookeries (h = 0.532). A mixed-stock analysis revealed that the South American pelagic aggregate is primarily composed of individuals from West Africa (84%), with contributions from the North Atlantic rookeries (14%). Leatherback turtles appear to have a complex phylogeographic pattern, showing evidence of multiple colonization events and a lack of isolation by distance. Our novel dataset, based on DNA sequences of 695 base pairs, will provide baseline data needed to understand population dynamics in the region, building comprehensive population assessments to support and develop management strategies. Having both the only known regular rookery in the South-west Atlantic, and a mixed-origin foraging area for the species along its coast, Brazil has a key role in the conservation of the leatherback turtle.

Sea turtles host a diverse array of epibionts, yet it is not well understood what factors influence epibiont community composition. To test whether epibiont communities of sea turtles are influenced by the hosts’ nesting or foraging habitats, we characterized the epibiota of leatherback, olive ridley and green turtles nesting at a single location on the Pacific coast of Costa Rica. We also compared the epibiota of these turtles to conspecific populations nesting elsewhere in the East Pacific. If epibiont communities are influenced by nesting habitats, we predicted that sympatrically nesting turtles would have comparable epibiont taxa. Alternatively, if epibiont communities are influenced by foraging habitats, we predicted the diversity of epibiont taxa should reflect the type and diversity of the hosts’ foraging habitats. We identified 18 epibiont taxa from 18 leatherback, 19 olive ridley and six green turtles. Epibiont diversity was low on leatherbacks (four taxa), but higher for olive ridley and green turtles (12 and nine epibiont taxa respectively). The epibiont communities of olive ridley and green turtles were not statistically different, but both were different from leatherbacks. In addition, conspecific sea turtles from other nesting locations hosted more similar epibiont communities than sympatrically nesting, non-conspecifics. We conclude that epibiont diversity of nesting sea turtles is partially linked to the diversity of their foraging habitats. We also conclude that the surface properties of the skin and carapace of these turtles may contribute to the uniqueness of leatherback turtle epibiont communities and the similarities between olive ridley and green turtle epibiont communities.

The beaches of Jaragua National Park in the Dominican Republic are the country's last known major nesting site for the leatherback marine turtle Dermochelys coriacea. This nesting aggregation is threatened by widespread illegal egg take, and clutch relocation and artificial incubation have been carried out as protection measures since 1974. We assess the efficacy of such efforts and investigate how artificial incubation may be influencing the success and sex ratios of clutches. We compare hatching success, incubation duration and embryo mortality in in-situ clutches (n = 43) with those incubated artificially at sites in the east and west of the Park (n = 35 and n = 31, respectively). Our results show that in the west, artificial incubation significantly decreases hatching success in clutches. In the east the duration of incubation is increased, which we predict would result in an increase in the number of males from these clutches. Clutch relocation is currently the only viable conservation option for clutches on eastern beaches because of illegal egg take but action is needed to ensure that the natural sex ratio is not distorted. However, on the western beaches in situ clutch incubation seems possible through beach protection. Further community engagement and enforcement are required to improve conservation measures at eastern beaches if long-term, less sustainable intervention is to be avoided.

Psephophorus polygonus Meyer, 1847, the first fossil leatherback turtle to be named, was described on the basis of shell ossicles from the middle Miocene (MN6–7/8?) of Slovakia. The whereabouts of this material is uncertain but a slab on display at the Naturhistorisches Museum Wien is considered the neotype. We rediscovered further type locality ossicles in four European institutions, re-evaluated their gross morphology and described for the first time their microstructure by comparing them with Dermochelys coriacea, the only living dermochelyid turtle. The gross morphology is congruent with that already described for P. polygonus, but with two significant exceptions: the ridged ossicles of P. polygonus may have a distinctly concave ventral surface as well as a tectiform shape in cross-section. They do not develop the external keel typical of many ossicles of D. coriacea. Both ridged and non-ridged ossicles of P. polygonus are characterized by compact diploe structures with an internal cortex consisting of a coarse fibrous meshwork, whereas the proportionately thinner ossicles of D. coriacea tend to lose the internal cortex, and thus their diploe, during ontogeny. The ossicles of both P. polygonus and D. coriacea differ from those of other lineages of amniotes whose carapace is composed of polygonal ossicles or platelets, in having growth centres situated at the plate centres just interior to the external bone surface and not within the cancellous core or closer to the internal compact layer. The new diagnosis of P. polygonus allows us to preliminarily re-evaluate the taxonomy of some of the Psephophorus-like species. Despite some macro- and micromorphological differences, it seems likely that Psephophorus was as cosmopolitan as extant Dermochelys and had a broadly similar ecology, with a possible difference concerning the dive depth.

Nesting by marine turtles in the Caribbean has declined considerably, mainly because of human exploitation, but there has previously been no monitoring in the Dominican Republic. We present the first detailed assessment of the status of marine turtle nesting in the country, based on surveys during 2006–2010. Nesting populations of hawksbill Eretmochelys imbricata and leatherback turtle Dermochelys coriacea are of regional importance and the green turtle Chelonia mydas is still present, although nesting in low numbers. The two main nesting sites are within protected areas: the Jaragua National Park in the south-west, important for leatherback turtles (mean of 126 nests per season), and Del Este National Park on Saona Island in the south-east, principally for hawksbill turtles (mean of 100 nests per season). Comparison with historical data suggests all rookeries are profoundly reduced in size. Although the main nesting beaches are within protected areas, illegal egg-take and meat consumption continues there, and also elsewhere in the country.

Predation can be an important driver of population dynamics but can also pose a dilemma to conservation managers if the species interacting are of conservation concern or have a high public profile. For 5 years we conducted regular transect surveys to monitor the spatial and temporal patterns of predation of adult marine turtles by jaguars Panthera onca in Tortuguero National Park, Costa Rica. Predation occurs throughout the study site on Tortuguero Beach although at lower rates at the northern and southern ends, probably because of increased human presence in these areas. There was a marked increase in predation, from an average of < 2 turtles predated per survey in the first season to > 5 predated per survey in the last, with 676 jaguar-predated marine turtles recorded during the study period. With a minimum of 189 individuals predated in the last season, predation of adult turtles has now reached a magnitude never before recorded in a marine turtle rookery. Although the nesting population of marine turtles in Tortuguero is one of the largest in the world and suffers from both direct and indirect anthropogenic pressures, the increase in predation by jaguars makes this ecological interaction relevant to the management of both the jaguar and marine turtle populations. The situation could lead to a potential conflict in conservation strategies that, given the flagship role of the species involved, will need to be addressed both in the context of species management and conservation marketing.

Six marine turtle species are reported from the coastal waters of the Republic of the Congo. Among them, nesting by the Critically Endangered leatherback Dermochelys coriacea and Endangered olive ridley Lepidochelys olivacea marine turtles occurs annually from September to April on Congolese beaches. We developed a methodology to model the nesting season of marine turtles and apply it to the time series of nest counts for six nesting beaches monitored over 2–4 years. There is a peak of nesting activity in early January for leatherback turtles and early December for olive ridley turtles. We show a decline of olive ridley nests during this period whereas leatherback nesting increased, and propose that differential threats for these two species explain such a contrasted pattern.

Ecotourism is often suggested as a tool for promoting conservation but evidence for its usefulness is mixed. The success of conservation projects is widely recognized to depend upon the positive attitudes of local communities and thus it is important to know if ecotourism affects local perceptions of natural resources and conservation, as these can be important determinants of conservation behaviour. Rapid Rural Appraisal and questionnaire-based interviews were used to investigate this issue in the village of Grande Riviere, Trinidad. This has a community-based ecotourism programme for leatherback turtles Dermochelys coriacea, and is also one of the few sites where the Critically Endangered endemic Trinidad piping-guan Pipile pipile may be sighted. Topics addressed were knowledge and awareness of local conservation issues, focusing on attitudes to the environment in general, turtles and the Trinidad piping-guan. Ecotourism significantly affected perceptions. Villagers showed more awareness and support for turtle conservation than for the piping-guan or any other wildlife. Moreover, those households directly benefiting from the ecotourism industry had better knowledge of local natural resources and greater general awareness of conservation issues (not limited to turtles). Other socio-economic factors such as education and income also affected attitudes and knowledge but the ecotourism effect was still present after accounting for these. Hunting was seen as the main threat to wildlife but was also a popular pastime, illustrating the potential for mismatch between attitudes and conservation behaviours.

Air-breathing diving animals are capable of maintaining activity during prolonged dives fuelled by on-board oxygen stores. Leatherback turtles (Dermochelys coriacea) perform the deepest and longest dives among sea turtles, and are among the most prolific air-breathing divers. Here we report the longest dive duration for D. coriacea during an extremely deep dive (1186 m) that lasted 86.5 minutes. This dive duration exceeded previously published calculated aerobic dive limits by almost two-fold and extends our knowledge of the diving capacity of this species.

The globally distributed leatherback turtle Dermochelys coriacea is subject to fisheries bycatch throughout its range. Protection from fisheries within pelagic foraging habitats is difficult to achieve but may be more tractable when populations are concentrated near neritic breeding and nesting grounds. We used satellite telemetry to describe patterns of habitat utilization during the inter-nesting period for seven leatherback turtles nesting at Mayumba National Park in Gabon on the equatorial West African coast. The National Park includes critical nesting grounds and a marine protected area to 15 km offshore. Turtles dispersed widely from the nesting beach spending a mean of 62 ± SD 26% of tracking time outside the confines of the National Park. This propensity to disperse is likely to increase the chance of deleterious interactions with fisheries in the region. Patterns of habitat utilization indicate the need for wider spatial scale planning on the West African continental shelf to enhance protection of leatherback turtles when they are seasonally occupying these habitats in great numbers for breeding and nesting.

Industrial logging is expanding rapidly in Central African rainforests. We suggest that logging operations in this region pose an indirect threat to nesting marine turtles, especially the Critically Endangered leatherback turtle Dermochelys coriacea. This occurs because some logs are being lost or abandoned during downriver transport to coastal timber yards; the lost logs float out to sea and then often wash ashore, where they accumulate on beaches used by nesting turtles. We used a light aircraft to survey logs along the entire coastline of Gabon, and also studied the impacts of logs at Pongara Beach, one of the world's most important turtle nesting areas, during the 2002-2003 and 2003-2004 breeding seasons. Nearly 11,000 lost logs were counted along Gabon's beaches, with an estimated commercial value of USD 11.1 million. Logs were unevenly distributed along the coast, reaching a peak density of 247 logs km-1. At Pongara, logs blocked 30.5% of the beach. These logs had a number of negative effects on marine turtles, causing 8-14% of all nesting attempts (n = 2,163) to be aborted or disrupted. Initiatives to remove lost logs and driftwood from critical nesting beaches may be the most effective means to reduce their deleterious impacts on threatened marine turtles.

The goal of this study was to quantify marine turtle nesting activity by species, identify threats to their populations, and provide recommendations for their conservation on the south-east coast of Nicaragua. One survey was conducted in each of 1998 and 1999, and 10 surveys in 2000. The majority of nesting emergences were by leatherback Dermochelys coriacea and hawksbill Eretmochelys imbricata turtles, with some nesting also by green turtles Chelonia mydas. In 2000, egg poaching was highest for green turtle (83%) and hawksbill (75%) clutches. A total of 87 dead stranded turtles were encountered, of which at least 63.2% were green, 10.3% hawksbill, and 6.9% loggerhead turtles. The principal threats to marine turtle populations on the south-east coast of Nicaragua were the killing of nesting females, egg poaching, and bycatch in commercial and artisanal fisheries.

Leatherback turtle Dermochelys coriacea nesting has declined on Pacific beaches and as a result the species is considered Critically Endangered. Atlantic populations are, however, also important for the species' survival and therefore we undertook a study to quantify the size and nesting trend of the Caribbean Costa Rica and Panama leatherback turtle rookery. Tag returns show that post-nesting females from the rookery disperse throughout the Caribbean, Gulf of Mexico and North Atlantic. Aerial and track survey results were used to estimate 5,759–12,893 nests per year between San Juan river and Chiriquí beach, making this the fourth largest rookery worldwide. Monitoring results from three beaches (Tortuguero, Pacuare and Gandoca) were used to examine any temporal trend in nesting using nonparametric regression. Nesting appeared to decline slightly from 1995 to 2003 but the trend could be an artefact of interannual variation in nest numbers. Explanations for the difference in nesting trends over the past 15 years for Pacific (rapid decline) and Caribbean (slight decline or stable) rookeries include: (1) hatching success on Caribbean beaches has been higher due to dispersed nesting, (2) fisheries bycatch has been greater in the Pacific, and (3) less overlap between fishing areas and leatherback turtle habitats in the Atlantic. Quantification of human-caused mortality of all life stages and knowledge of the marine habitats used by Atlantic leatherback turtles are required to facilitate the development and implementation of effective strategies to reduce threats and avoid a repeat of the decline that has occurred in the Pacific population.