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Leatherback turtles (Dermochelys coriacea) have declined dramatically in the eastern Pacific Ocean (EP) in recent decades. Traditionally, population assessments have relied on the numbers of turtles on the beaches with the highest abundance of turtles (index beaches) and often disregarded the importance of nesting beaches with smaller, but still regular, numbers of nesting turtles (secondary beaches). We characterize leatherback nesting on secondary beaches throughout Pacific Costa Rica. Nesting distribution was significantly reduced since the 1990s and it currently appears to be constricted to the Santa Elena and Nicoya peninsulas. Over the past five years, nesting abundance on secondary beaches was low, ranging between 0.4 ± 0.5 and 5.3 ± 1.5 females and 3.8 ± 5.2 and 22.8 ± 10.8 nests per beach and per year. There was some exchange of turtles between beaches. The exchange rate (percentage of females that nested at least once on a different beach) ranged between 7% and 28%. While Caletas still registers multiple clutches that are laid by 1-2 females in some years, it may no longer qualify as a secondary beach due to the infrequent nature of nesting events registered recently and the total absence of nests in some of those years. Although nesting abundance is relatively low at secondary beaches, they host at least ~25% of total leatherback nesting abundance in Costa Rica. As the EP leatherback turtle declines, not only do the numbers of nesting turtles decrease but local extirpations are occurring on, previously categorized, secondary beaches. The critically low number of turtles at present may prevent recolonization of sites where they have been extirpated. [ABSTRACT FROM AUTHOR]

Nesting female Leatherback Turtles (Dermochelys coriacea (Vandelli, 1761)) are ungainly and vulnerable to predation, stranding, and physiological stress, dangers encountered repeatedly in a nesting season. Minimising these risks must be balanced against optimising investment in nest-site selection, excavation, refilling, and concealment of their egg clutches. We investigated the relative investment in the different phases of nesting in Leatherback Turtles by recording the duration of, and respiratory frequency during, each phase. Nest excavation and the final sand scattering (usually termed "camouflage" or "disguise") phases were the longest in duration. By combining the relative durations of nesting phases with literature estimates of oxygen consumption, we found that these may be the most expensive phases energetically, sand scattering in particular. Leatherback Turtles follow convoluted paths during the sand scattering phase, which were mapped and measured. They disturb large areas (mean (±SD) 30.3 ± 11.1 m², maximum 57 m²), the centroids of which were always offset from the nest itself. Interestingly, in none of 26 nestings observed did the centre line of females move over the nest itself. Nesting Leatherbacks therefore invest heavily in obscuring the egg clutch, and the pattern of their movements in doing so suggests decoy behaviour. [ABSTRACT FROM AUTHOR]

The leatherback turtle Dermochelys coriacea, the only extant species in its family, is categorized as Vulnerable on the IUCN Red List. The protection of nesting beaches and the associated conservation efforts along the Western Atlantic coast of Central America have improved the population trends of some of the most important rookeries. Here we report the life history, ecology and population trends of leatherback turtles over 18 years (1994–2012, excluding 1998) of effective protection in the Pacuare Nature Reserve, on the Caribbean coast of Costa Rica. A mean density of 142 nests per km, probably the highest in Central America, indicates the importance of this rookery within the Caribbean region. Long-term conservation efforts at the Reserve have significantly reduced poaching and contributed to maintaining a high level of hatchling production. Long-term monitoring has also facilitated estimation of relevant demographic parameters of the population, such as nesting success (mean 69.8 ± SD 7.3%), clutch size (which is positively correlated with female size), hatching success (mean 55.2 ± SD 6.0%), remigration interval (2.5 years), and growth rate of remigrant females (mean 0.3 ± SD 1.0 cm per year), which is slightly faster than growth rates reported for Pacific leatherback turtles. Overall, efforts at Pacuare have been successful in protecting leatherback turtles and understanding their life history, highlighting the importance of long-term conservation projects for maintaining threatened leatherback populations. [ABSTRACT FROM AUTHOR]

Leatherback sea turtles ( Dermochelys coriacea) are endangered throughout their range. To protect these animals, research is needed to develop conservation programs that protect the turtles during all of their life activities, including foraging, breeding, nesting, and hatching. The purpose of this study was to focus on issues related to nesting by determining whether environmental and climatic factors influence nesting for female leatherback sea turtles. A variety of climatic and environmental samples were collected during the nesting season from May to July 2008. Data were collected during nesting events and nonnesting events for comparison. Leatherback sea turtles were found to be significantly more likely to nest during the later lunar phases ( P = 0.001) and when cloud cover was low (<50%) over the natal beaches ( P = 0.02). Sand conductivity was significantly lower ( P = 0.008) at the nesting level (0.01 μS/cm) of the sand compared with the surface sand (0.09 μS/cm). There were also significant differences in the pH ( P = 0.001) of the sand taken at control surfaces and nesting surfaces, along with significant differences between the control samples taken from nest depth compared to turtle nests in pH ( P = 0.020), temperature ( P = 0.037), and sand grain size ( P = 0.001). These findings suggest that select climatic and environment factors do vary between nesting and nonnesting sites in the leatherback sea turtle, and it is possible that these differences could ultimately influence when and where the females deposit their eggs. This information should be considered when developing conservation plans for the leatherback sea turtle, including habitat management and personnel use during the nesting season. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Leatherback turtles ( Dermochelys coriacea ) are the largest species of marine turtle and the fourth most massive extant reptile. In temperate waters they maintain body temperatures higher than surrounding seawater through a combination of insulation, physiological, and behavioural adaptations. Nesting involves physical activity in addition to contact with warm sand and air, potentially presenting thermal challenges in the absence of the cooling effect of water, and data are lacking with which to understand their nesting thermal biology. Using non-contact methods (thermal imaging and infrared thermometry) to avoid any stress-related effects, we investigated core and surface temperature during nesting. The mean±SE core temperature was 31.4±0.05 °C (newly emerged eggs) and was not correlated with environmental conditions on the nesting beach. Core temperature of leatherbacks was greater than that of hawksbill turtles ( Eretmochelys imbricata ) nesting at a nearby colony, 30.0±0.13 °C. Body surface temperatures of leatherbacks showed regional variation, the lateral and dorsal regions of the head were warmest while the carapace was the coolest surface. Surface temperature increased during the early nesting phases, then levelled off or decreased during later phases with the rates of change varying between body regions. Body region, behavioural phase of nesting and air temperature were found to be the best predictors of surface temperature. Regional variation in surface temperature were likely due to alterations in blood supply, and temporal changes in local muscular activity of flippers during the different phases of nesting. Heat exchange from the upper surface of the turtle was dominated by radiative heat loss from all body regions and small convective heat gains to the carapace and front flippers. [ABSTRACT FROM AUTHOR]

Climate change models predict sea level rise and increased intensity of storms and hurricanes in tropical sea turtle nesting areas. These factors could significantly increase beach inundation and erosion, thus affecting water content of sea turtle nesting beaches. Here, we conducted a field and laboratory study of how sand water content is related to embryonic development and hatching success of leatherback turtle nests. Moreover, we have experimentally incubated eggs of this species in beach sand under standardized conditions, but at different realistic levels of sand water content, varying from 1% to 12%. On the beaches, females nested from the intertidal zone to the lower part of the sand vegetation dunes, where nests were exposed to a wide range of sand water contents that ranged from 0.8% to 22%. However, both field and experimental studies revealed a strong negative correlation between sand water content and emergence success (field study: r = − 0.73, P < 0.0001; experiment: r = − 0.84, P < 0.0001). In the field, mean emergence success varied from 0% for the wettest nests to 64% for the driest ones. Nests in wet sand suffered higher mortality, primarily in the earlier developmental stages. Eggs incubated in the driest sand lost mass, but there were no significant effects on hatchling mass or run speed compared to eggs that gained water during incubation. However, hatchling straight carapace length (SCL) was greater in eggs from the driest treatment. The results of the present study inform management of change under future climate change sea level rise scenarios, suggesting that leatherback turtle nesting success should be expected to decrease. [ABSTRACT FROM AUTHOR]

Despite facing serious threats of extinction in the Eastern Pacific, the leatherback turtle (Dermochelys coriacea) appears to be thriving in the Atlantic basin based on increasing nest counts at several rookeries. In particular, Florida's nest numbers have been increasing by 10.2% per year since standardized counts began in 1979. The US Recovery Plan for leatherbacks calls for vital rates and population parameters to be determined for the three leatherback rookeries under US jurisdiction: St. Croix (USVI), Puerto Rico, and the east coast of Florida. Based on mark-recapture data gathered over eleven years, we determined important population parameters for nesting female leatherbacks at Juno Beach, one of the most densely nested beaches in Florida. Average annual survival was 88.9%. The average female nesting population size for Juno Beach is estimated at 100 ± 41 individuals each season; statewide we expect the estimate to be higher. The average remigration interval was 2.7 ± 1.0 years. In addition, we report observed clutch frequency (2.1 ± 1.4 clutches/year), estimated clutch frequency (4.4 ± 1.1 nests/year), and observed internesting period (10.2 ± 1.3 days between nests). The probability of observing an individual female at least once during the season was 73.0%, likely due to variable site fidelity, even though sea turtles do exhibit natal homing. Using opportunistic observations at additional beaches, we found that 72 females observed nesting within the Juno Beach study area were also observed nesting outside the study area. Thirty-three individuals laid clutches both inside and outside the survey area within a single season; these nests were separated by as much as 463.5 km. Although the population in Florida is relatively small compared to other rookeries throughout the Western Atlantic, it is increasing at such a rapid pace that it has the potential to become more important regionally, thereby contributing to the abundance of leatherbacks in the Atlantic. [ABSTRACT FROM AUTHOR]

Coastal development can alter the natural dynamics of beach environments, with strong implications for associated biota. Sea turtles nest on oceanic beaches and often depend upon a specific range of conditions for successful nesting. In the case of the critically endangered leatherback turtle (Dermochelys coriáceo), we know little regarding what features they select for nest sites, including how they respond to anthropogenic development. We examined relationships between leatherback nest frequency, beach environments, and tourism development at Playa Grande, Costa Rica, the location of the largest current nesting population in the eastern Pacific Ocean. Developed beach sections had shallower slopes, lower pH, and less air-filled pore space, but higher water content and salinity than undeveloped areas. Developed areas were also comprised of more sand in the smaller grain size classes relative to undeveloped sections. Leatherback nesting was positively correlated with deepness of the offshore approach, beach slope and elevation, pH, and sand in intermediate size classes (0.025-mm diameter), but negatively correlated with sand in the smallest silt size class ( < 0.0625-mm diameter). Leatherback nesting frequency was 3.4 times higher in undeveloped sections of the beach relative to developed areas, while nonnesting emergences were 2.6 times more likely in developed relative to undeveloped areas. It is apparent that coastal development has impacted beach environments with consequences for leatherback nest site distribution. It is likely that additional development of the beach under mixed-management plans to support a growing tourist industry will further degrade the attractiveness and quality of the beach for leatherback nesting. [ABSTRACT FROM AUTHOR]

Abstract: The African country of Gabon has seen decadal increases in commercial logging. An unforeseen consequence of this has been that many coastal areas, including several National Parks and Reserves, have suffered severe pollution from beached timber. This has the potential to adversely affect nesting sea turtles, particularly the leatherback turtle (Dermochelys coriacea) for which Gabon constitutes the world’s largest rookery. In this study, we analyse aerial survey data (2003, 2007 and 2011) to determine the temporal persistence and spatial extent of beached timber, and by integrating spatial data on nesting, ascertain regions where beached timber poses the greatest threat to nesting leatherback turtles. There was no marked difference in the number of beached logs recorded across the study area during the period, with 15,160, 13,528 and 17,262logs recorded in the three years, respectively. There was, however, a significant difference in abundance of beached logs among geographical areas. Analysis highlighted two coastal areas where nesting leatherback turtles were likely to be at greatest risk from beached timber. At one such site, Kingere, within Pongara National Park, where both logs and turtle densities are high, monitoring in 2006/2007 and 2007/2008 suggested that between 1.6% and 4.4% of leatherback turtles could be entrapped at this site. Given the dynamic nature of Gabon’s coastal environment, and the potential limitations of aerial surveys, densities of beached timber could be greater than this analysis reveals. We also propose, that despite recent export restrictions of whole logs, their environmental persistence potentially represents a long-term problem. [Copyright &y& Elsevier]

The article offers information on possible causes of mortality for adult leatherback turtles (Dermochelys coriacea). It states that a switching state-space model was applied to distinguish migratory and area-restricted search behaviors. It indicated a high spatial segregation between East Pacific(EP) and West Pacific(WP) nesting populations.They have high risk of exposure to many different fisheries and more susceptible to any temperature or prey changes that occur in response to climate change.

Africa's Gulf of Guinea, a major nesting ground for the critically endangered Leatherback Sea Turtle (Dermochelys coriacea), is experiencing rapid economic development. This study reports on the plasma biochemistry and packed cell volume (PCV) of turtles (55 samples collected from 23 individuals) nesting on Playa Moaba, Bioko Island, Equatorial Guinea. Because energy reserves and other resources in an individual are finite and turtles may not feed between nesting episodes, decreasing trends are expected in certain plasma biochemical concentrations and PCV values, as well as maternal investment in reproductive output (clutch size and egg mass). Calcium, potassium, sodium, phosphorous, plasma total protein, albumin, and globulin concentrations changed significantly with increasing number of nesting events, but remained within reported intervals in reptiles. Packed cell volume decreased significantly as the number of nesting events per individual increased. Although clutch size did not change, egg mass decreased significantly with increasing number of nesting events. The observed trends may be due to depletion of energy reserves and other resources during reproduction in a possible fasting state, and to the associated physiological stress. [ABSTRACT FROM AUTHOR]

Abstract: Leatherback sea turtles (Dermochelys coriacea) have low hatching and emergence success compared to other sea turtle species. Postmortem examinations of hatchlings showed degeneration of heart and skeletal muscle that was similar to that found in other neonates with selenium deficient mothers. Selenium deficiency can result from elevated concentrations of bodily mercury. Ingested mercury is detoxified by the liver through mercury–selenium compound formation. In animals persistently exposed to mercury, the liver’s ability to detoxify this element may decrease, especially if dietary selenium is insufficient. We measured mercury and selenium concentrations in nesting female leatherbacks and their hatchlings from Florida and compared the levels to hatching and emergence success. Both liver selenium and the liver selenium-to-mercury ratio positively correlated with leatherback hatching and emergence success. This study provides the first evidence for the roles of mercury and selenium in explaining low reproductive success in a globally imperiled species, the leatherback sea turtle. [Copyright &y& Elsevier]

Leatherback turtles in the Pacific Ocean have declined precipitously in recent decades. One issue that may be contributing to the declines of leatherbacks and impairing their recovery is low clutch viability resulting from high embryonic mortality. Here, we examine trace metal concentrations in eggs and hatchlings from leatherbacks nesting on the Pacific coast of Costa Rica to assess whether contaminant levels reflect variation in the time over which females accumulated contaminants and whether variation in egg contaminant concentrations among nests influences clutch viability and hatchling characteristics. Eggs and hatchlings of Pacific leatherbacks contained detectable concentrations of a suite of essential and nonessential metals including Cu, Cd, Fe, Mn, Ni, and Zn, but variables that likely reflect a female's degree of temporal exposure to contaminants (relative age of female, body size, and remigration interval) explained little of the variation in egg metal concentrations. Concentrations of Cu, Cd, Fe, and Ni in Pacific leatherbacks were higher or toward the upper range of metal levels examined in sea turtle eggs elsewhere, but we did not find evidence linking egg contaminant levels with clutch success or hatchling size or body condition. These results represent the most comprehensive measures of trace metal concentrations from leatherback turtles in the eastern Pacific Ocean. [ABSTRACT FROM AUTHOR]

Leatherback turtles have an average global hatching success rate of ∼50%, lower than other marine turtle species. Embryonic death has been linked to environmental factors such as precipitation and temperature, although, there is still a lot of variability that remains to be explained. We examined how nesting season, the time of nesting each season, the relative position of each clutch laid by each female each season, maternal identity and associated factors such as reproductive experience of the female (new nester versus remigrant) and period of egg retention between clutches (interclutch interval) affected hatching success and stage of embryonic death in failed eggs of leatherback turtles nesting at Playa Grande, Costa Rica. Data were collected during five nesting seasons from 2004/05 to 2008/09. Mean hatching success was 50.4%. Nesting season significantly influenced hatching success in addition to early and late stage embryonic death. Neither clutch position nor nesting time during the season had a significant affect on hatching success or the stage of embryonic death. Some leatherback females consistently produced nests with higher hatching success rates than others. Remigrant females arrived earlier to nest, produced more clutches and had higher rates of hatching success than new nesters. Reproductive experience did not affect stage of death or the duration of the interclutch interval. The length of interclutch interval had a significant affect on the proportion of eggs that failed in each clutch and the developmental stage they died at. Intrinsic factors such as maternal identity are playing a role in affecting embryonic death in the leatherback turtle. [ABSTRACT FROM AUTHOR]

Florida (United States) beaches serve as globally important nesting habitat for protected species of sea turtles. Following coastal development, portions of this habitat have become inaccessible to nesting sea turtles due to coastal armoring and other barriers. To assess nesting habitat quality, we randomly selected beaches totaling 80.45 km in each of four regions of Florida (northeast, southeast, northwest, and southwest) and surveyed them for potential barriers to nesting during the period of April 2001 to May 2002 (total surveyed coastline 5 321.8 km). Potential barriers to nesting were found in 78 forms on sampled beaches, including seawalls, revetments, sand bags or tubes, sand fences, access structures, recreational equipment, and buildings. We determined the position and extent of structures using a differential global positioning system. Surveyed beaches made up 24.5% of Florida's sandy coastline and were sampled to be regionally representative. In an assessment summed for all regions, potential barriers to nesting occupied 18.0% of the total surveyed beach length. The region with the greatest extent of potential barriers was southeast (23.8%), followed by southwest (21.7%), northwest (14.1%), and northeast (12.3%). Seawalls were the most common potential barriers in all but the northwest region, where sand fences were most common. Our measurements did not include structures that were hidden from view by sand or other structures. Following coastal effects from four major hurricanes that made landfall in 2004, we resurveyed 16 km of beach in each region (total 5 64 km). We recorded a net reduction of sand fencing in northeast and northwest Florida and a net reduction of revetment rocks in the southwest region due to covering by sand. However, the linear extent of barriers increased in northeast and southwest due to seawall construction and additional sand fencing. [ABSTRACT FROM AUTHOR]

The article presents a study which investigates the population status of leatherback nests in Florida. The study uses a multilevel Poisson regression to know the rate of growth for leatherback turtle nest numbers and to recognize the hierarchical structure of the data while integrating variables related to survey report. Results show that marine food web dynamics and climate variability which could improve productivity and decrease predators may served as the driving factors of the said trend.

Background: Sea turtles are long-distance migrants with considerable behavioural plasticity in terms of migratory patterns, habitat use and foraging sites within and among populations. However, for the most widely migrating turtle, the leatherback turtle Dermochelys coriacea, studies combining data from individuals of different populations are uncommon. Such studies are however critical to better understand intra- and inter-population variability and take it into account in the implementation of conservation strategies of this critically endangered species. Here, we investigated the movements and diving behaviour of 16 Atlantic leatherback turtles from three different nesting sites and one foraging site during their post-breeding migration to assess the potential determinants of intra- and inter-population variability in migratory patterns. Methodology/Principal Findings: Using satellite-derived behavioural and oceanographic data, we show that turtles used Temporary Residence Areas (TRAs) distributed all around the Atlantic Ocean: 9 in the neritic domain and 13 in the oceanic domain. These TRAs did not share a common oceanographic determinant but on the contrary were associated with mesoscale surface oceanographic features of different types (i.e., altimetric features and/or surface chlorophyll a concentration). Conversely, turtles exhibited relatively similar horizontal and vertical behaviours when in TRAs (i.e., slow swimming velocity/sinuous path/shallow dives) suggesting foraging activity in these productive regions. Migratory paths and TRAs distribution showed interesting similarities with the trajectories of passive satellite-tracked drifters, suggesting that the general dispersion pattern of adults from the nesting sites may reflect the extent of passive dispersion initially experienced by hatchlings. Conclusions/Significance: Intra- and inter-population behavioural variability may therefore be linked with initial hatchling drift scenarios and be highly influenced by environmental conditions. This high degree of behavioural plasticity in Atlantic leatherback turtles makes species-targeted conservation strategies challenging and stresses the need for a larger dataset (>100 individuals) for providing general recommendations in terms of conservation. [ABSTRACT FROM AUTHOR]

We evaluate the conservation status and threats faced by sea turtle nesting populations at Bioko Island, Equatorial Guinea (Central Africa). Beaches were monitored to obtain a detailed sea turtle nest census and, where possible, tagging of adult females was undertaken. Four sea turtle species were found nesting in the area: the green turtle ( Chelonia mydas), the leatherback ( Dermochelys coriacea), the olive ridley ( Lepidochelys olivacea) and the hawksbill ( Eretmochelys imbricata); with the former two species nesting in regionally important numbers. Nesting activity was concentrated between November and February, with a peak in December–January. Tagging and recapture of green turtles in two consecutive seasons suggested an estimated 560 (interquartile range: 420–1,681) and 414 (interquartile range: 190–1,255) nesting females in the area, respectively. Estimated numbers of nesting leatherbacks ranged from 123 to 215 and 243 to 293 in the first and second season, respectively. The other two species were less abundant (olive ridley: 19–29 and 28–43; hawksbill: 4–10 and 2 turtles). Data were compared with more recent surveys in the area and contextualised with information on human related threats. Despite the size of nesting stocks, ongoing permitted and illegal take of adult turtles at the nesting site constitutes a serious threat for these breeding aggregations. Additionally, tag returns from throughout the Gulf of Guinea suggest that the level of take in regional fisheries may also be a major threat. [ABSTRACT FROM AUTHOR]

Abstract: We examined the maternal transfer of organochlorine contaminants (OCs), pesticides (DDTS and HCHs) and polychlorinated biphenyls (PCBs), and the temporal variation of blood and eggs concentrations from 38 leatherback turtles (Dermochelys coriacea) nesting in French Guiana. PCBs were found to be the dominant OCs with respective mean concentrations of 55.14ngg−1 lipid-mass for egg and 1.26ngmL−1 wet-mass for blood. OC concentrations were lower than concentrations measured in other marine turtles which might be due to the lower trophic position (diet based on gelatinous zooplankton) and to the location of their foraging and nesting grounds. All OCs detected in leatherback blood were detected in eggs, suggesting a maternal transfer of OCs. This transfer was shown to depend on female blood concentration for ΣDDTs and for the most prevalent PCB congeners, since significant relationships were found between paired blood–egg concentrations. During the nesting season, OC concentrations in eggs and the percentage of lipid in eggs were found to decline in successive clutches, highlighting a process of offloading from females to their eggs and a decreasing investment of lipid from females into their clutches. OCs in eggs tended to be higher in females spending 3years in the foraging grounds between two nesting seasons than in those spending 2years, suggesting an impact of time spacing two breeding seasons, called remigration interval, and of location of the foraging grounds. [Copyright &y& Elsevier]

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. [ABSTRACT FROM AUTHOR]

Abstract: Understanding environmental cues determining behaviour and habitat use of species of conservation concern is crucial if one aims at implementing sustainable management of these natural resources. In this way, here, we investigate the thermal and trophic conditions encountered by the critically endangered leatherback sea turtle Dermochelys coriacea during its nesting season in French Guiana where high bycatch rates have been reported. Mean sea water temperatures obtained in situ by animal-borne recorders were 26.6±0.7 °C in the water column, with all but one turtle remaining in water >25 °C during the inter-nesting interval. In terms of prey availability, regular jellyfish stranding events were recorded during the nesting season, on a 1.25-km long section of the nesting beach. The occurrence of jellyfish was supported by benthic trawls performed on the continental shelf, with a total of 45.4 kg of jellyfish collected in 3.5 h exclusively in coastal waters 10 to 20 m deep where water transparency was between 0.8 and 3 m. This is consistent with the at sea distribution area of gravid leatherbacks during their inter-nesting intervals, as they spent almost 70% of their time diving in shallow (<20 m deep) waters in front of the Maroni River estuary. In French Guiana, leatherback''s gelatinous prey are thus present in very shallow water close to the nesting site and may be easily exploited by active gravid leatherbacks. This suggests that French Guiana female leatherbacks may be influenced by local trophic conditions and actively prospect productive areas overlapping with local fisheries ground. [Copyright &y& Elsevier]

Abstract: Over recent years there have been substantial efforts to record and interpret the post-nesting movements of leatherback turtles (Dermochelys coriacea) breeding in tropical regions. Less well documented are the movements undertaken by individual turtles during the breeding season itself, or more specifically between sequential nesting events. Such movements are of interest for two reasons: (1) gravid female leatherbacks may range extensively into the territorial waters and nesting beaches of neighbouring countries, raising questions for conservationists and population ecologists; and (2) the magnitude of movements themselves help elucidate underlying reproductive strategies (e.g. whether to rest near to the nesting or forage extensively). Here, satellite relay data loggers are used (SRDLs) to detail the movements and behaviour of two female leatherback turtles throughout three consecutive inter-nesting intervals in the Commonwealth of Dominica, West Indies. Both near-shore residence and extensive inter-nesting movements were recorded, contrasting previous studies, with movements away from the nesting beach increasing towards the end of the nesting season. Using this behavioural study as a backdrop, the suitability of attaching satellite transmitters directly to the carapace was additionally explored as an alternative approach to conventional harness deployments. Specifically, the principal aims were to (1) gather empirical data on speed of travel and (2) assess dive performance (aerobic dive limit) to enable comparisons with turtles previously fitted with harnesses elsewhere in the Caribbean (n =6 turtles; Grenada, WI). This produced mixed results with animals bearing directly attached transmitters travelling significantly faster (55.21 km day−1; SD 6.68) than harnessed individuals (39.80 km day−1; SD 6.19); whilst no discernable difference in dive performance could be found between the two groups of study animals. [Copyright &y& Elsevier]

Background: The leatherback turtle (Dermochelys coriacea) has undergone a dramatic decline over the last 25 years, and this is believed to be primarily the result of mortality associated with fisheries bycatch followed by egg and nesting female harvest. Atlantic leatherback turtles undertake long migrations across ocean basins from subtropical and tropical nesting beaches to productive frontal areas. Migration between two nesting seasons can last 2 or 3 years, a time period termed the remigration interval (RI). Recent satellite transmitter data revealed that Atlantic leatherbacks follow two major dispersion patterns after nesting season, through the North Gulf Stream area or more eastward across the North Equatorial Current. However, information on the whole RI is lacking, precluding the accurate identification of feeding areas where conservation measures may need to be applied. Methodology/Principal Findings: Using stable isotopes as dietary tracers we determined the characteristics of feeding grounds of leatherback females nesting in French Guiana. During migration, 3-year RI females differed from 2-year RI females in their isotope values, implying differences in their choice of feeding habitats (offshore vs. more coastal) and foraging latitude (North Atlantic vs. West African coasts, respectively). Egg-yolk and blood isotope values are correlated in nesting females, indicating that egg analysis is a useful tool for assessing isotope values in these turtles, including adults when not available. Conclusions/Significance: Our results complement previous data on turtle movements during the first year following the nesting season, integrating the diet consumed during the year before nesting. We suggest that the French Guiana leatherback population segregates into two distinct isotopic groupings, and highlight the urgent need to determine the feeding habitats of the turtle in the Atlantic in order to protect this species from incidental take by commercial fisheries. Our results also emphasize the use of eggs, a less-invasive sampling material than blood, to assess isotopic data and feeding habits for adult female leatherbacks. [ABSTRACT FROM AUTHOR]

Chiriqui Beach, in the Comarca Ngöbe-Buglé on the Caribbean coast of Panama, is the most important nesting beach for leatherback turtles (Dermochelys coriacea) in Caribbean Central America. Beach surveys during the 2003 and 2004 nesting seasons documented 3077 leatherback nests in one season and a minimum of 234 individual leatherbacks. Monitoring of nest fate revealed that predation by dogs represents the greatest human-related survival threat to leatherbacks at Chiriqui Beach, although the killing of leatherbacks from the same nesting population on beaches near the Panama-Costa Rica border also is of concern. [ABSTRACT FROM AUTHOR]

Nine leatherback turtles (Dermochelys coriacea) were tracked for 111-695 days via satellite telemetry from one of the largest remaining western Pacific leatherback turtle nesting beaches, Jamursba-Medi, Papua, Indonesia. The turtles moved into tropical waters of the Philippines and Malaysia, into the Sea of Japan, and across the equatorial Pacific to temperate waters off North America. This study provides the first record of a Irans. Pacific migration by a leatherback turtle. [ABSTRACT FROM AUTHOR]

Over 4 years, 2001-2004, leatherback turtle monitoring was conducted on all the potential nesting sites in French Guiana. We estimated minimal leatherback turtle nest numbers of 23,107. 12,229, 13,480, 11,012, respectively. The Awala-Yalimapo Beach, sometimes considered a good estimator of the overall nesting achy its for the country, has hosted a significant proportion of the leatherback turtle nests (42% ± 2%), but this percentage is much lower than formerly described. The relative importance of this nesting site is discussed in light of remote sensing data, suggesting that nest numbers recorded in Awala-Yalimapo may have misrepresented leatherback turtle population trends. Indeed, remote sensing data indicate that the total sands shoreline available in French Guiana has regularly evolved over the last decades, allowing leatherback turtle nesting attempts nut of the scope of monitoring. The importance of a monitoring effort integrating the specific coastal dynamic of the Guianas region is highlighted. [ABSTRACT FROM AUTHOR]

Leatherbacknesting along the Atlantic coast of Africa extends from Mauritania in the north to Angola in the south, with a globally important nesting concentration located in Gabon in Central Africa. Provisional estimates of nesting numbers from Gabon indicate that this nesting population may he among the largest in the world. [ABSTRACT FROM AUTHOR]

Leatherback turtle (Dermochelys coriacea) nesting activity was monitored, individual movements via flipper tag recoveries and satellite telemetry were determined, and illegal egg collection was quantified at Tortnguero, Costa Rica from 1995 to 2006. Annual nest deposition was estimated at 199-1,623 nests per year; a Bayesian regression model suggests that leatherback nesting decreased by 67.8% between 1995 and 2006. Tag recaptures from fisheries bycatch and strandings have been reported from Cuba, Nicaragua. and the United States. Two leatherbacks were followed with satellite telemetry; 1 swam to Cuba and I moved into the northwest Atlantic Ocean. Minimum rates for illegal egg collection from 2000 to 2005 were estimated at 13.0%-21.59%. [ABSTRACT FROM AUTHOR]

Playa Langosta is 1 of 3 nesting beaches in Parque Nacional Marino Las Baulas de Guanacaste, and is 1.3-km long. The 3 beaches (Langosta, Grande, and Ventanas) represent over 6 km of leatherback (Dermochelys coriacea) nesting. The use of passive integrated transponder (PIT) tags allowed us to identify each leatherback that nested at Playa Langosta. A total of 252 individual leatherbacks nested between the 1999-2000 and 2003-2004 nesting seasons. Of these, 63% (n = 158) were new turtles (untagged before), and 50% (n = 79) of the new turtles were originally PIT tagged on Playa Langosta. The majority of these turtles 54%) nested only on Playa Langosta, whereas a slightly smaller percentage (46%) nested at both Playa Grande and Playa Langosta. We recorded 904 encounters and 792 nests at Playa Langosta for the 5 nesting seasons of this study. Leatherbacks nesting at Playa Langosta ranged in curved carapace length from 125 to 164 cm and in curved carapace width, from 90 to 116 cm. Average internesting period was 9.6 days. For the first 4 seasons, data from excavated nests showed a decrease in percentage of hatching success from 68.9% to 30.4% in natural nesting conditions. A dramatic decline to emergence success from 57.2% to 9.3% occurred for these respective seasons. For the last 3 seasons, the hatching success of leatherback turtles in relocated nests was 52.4%, 18.9%, and 51.4%. [ABSTRACT FROM AUTHOR]

From 1985 to 1999, data were gathered opportunistically on the bycatch of 33 leatherback turtles in coastal Peru, and from 2000 to 2003, a dockside observer program provided data on an additional 133 leatherbacks caught in the coastal gilluet and longline fisheries targeting mahi mahi, sharks, and rays. These data stress the need for programs to monitor bycatch in artisanal fisheries. enforce regulations prohibiting sea turtle capture, and increase the environmental awareness of fishermen. [ABSTRACT FROM AUTHOR]

Spatial use of nesting habitat by Dermochelys coriacea is analyzed on a beach with intense tourism use on Margarita Island. There are no previously published data in Venezuela about the use of nesting habitat by leatherback sea turtles and the effects of human activities on nest location and hatching success. Data were collected during nightly intensive beach patrols on Playa Parguito beach (1.6-km long) from March through August 2001. Thirty-one females nested on the beach, and we found 74 nests. the average distance between pairs of nests from the same female was 498 m, although modal distance was between 200 and 300 m. The average distance between randomly selected pairs of nests from any female was 451 m. No special preference for a certain part of the beach for each female was found. Spatial analysis indicated nesting aggregates toward the most suitable portions of the beach: those with fewer risk factors (light pollution, concentration of beach furniture and umbrellas). Our results show nesting behavior change, causing decreased nesting in areas where the best hatching rates occurs. Hatching success was significantly higher in the southern part of the beach, hut the larger number of clutches were laid in the northern area, where hatching success was the lowest. Hatching rate for in situ clutches was 47.18%, which was significantly higher than that obtained for nests moved into a hatchery (33.1%) or for nests relocated to a safer part of the beach (27.8%). [ABSTRACT FROM AUTHOR]

Proyecto Laúd coordinates the conservation activities for the leatherback turtle on 4 index beaches of the Mexican Pacific, combining efforts of different government and nongovernment institutions. With more than 20 years of tagging and conservation data, this project represents the most solid source of knowledge about the biology and ecology of the leatherback turtle in Mexico. Daily nesting track counts done from 1982 to 2004 showed a declining trend for the number of leatherback nests on the 4 index beaches of the Mexican Pacific (Mexiquillo, Tierra Colorada, Cahuitán, and Barra de la Cruz). The worst nesting season was 2002-2003, in which only 120 leatherback nests were recorded on the index beaches combined. The decline is attributed to a combination of extensive egg harvest on all Mexican Pacific beaches before conservation activities and high mortality of large adults in pelagic fisheries. A total of 5314 females were individually identified since 1982; the average remigration interval is 3 years. and there is evidence of interchange of females between some beaches. The female population has an average curved carapace length of 143.8 cm and an average clutch size of 62 eggs. The average estimated clutch frequency is 5.5 ± 1.9, with an average clutch interval of 9.7 ± 1.2 days. From 1982 to 2004 a total of 270,129 leatherback hatchlings were released to the wild population. This comparatively small number was not enough to offset the mortality of juveulles and adults offshore. This may explain the continuing population decline in spite of 20 years of protection activities. Currently, hope for the future of the population relies on the protection of at least 80% of the clutches laid on the priority beaches, the participation of local communities in conservation activities, and increased awareness of the leatherback's status among Mexican society. [ABSTRACT FROM AUTHOR]

Suriname beaches support a major nesting colony of leatherback turtles. During the 1999-2005 nesting seasons, we collected data on nesting ecology and identified individual turtles that nested at Babunsanti (Galibi Nature Reserve), Samsambo, Kolukumbo, and Matapica. We observed 8462 leatherback females, 6933 of which we PlT-tagged. The remaining 1529 females carried PIT tags of a non-Surinamese origin. Because complete coverage of all nesting beaches was not possible over the study period, estimations of minimum annual nesting colony size were made, which ranged from 1545 to 5500 females in Suriname alone. Of the 7394 turtles observed during 1999-2004, 14.8% were seen renesting by 2005. Annual mean internesting period ranged between 9.4 ± 1.0 to 9.6 ± 1.0 days. Annual mean observed clutch frequency was between 1.6 ± 1.0 to 3.1 ± 1.4 and annual minimum estimated clutch frequency between 4.1 ± 1.6 to 4.9 ± 1.8 clutches. Annual mean standard curved carapace length ranged from 154.1 ± 6.7 to 155.6 ± 6.7 cm, and annual mean clutch size ranged from 80.8 ± 18.3 to 88.2 ± 19.5 yolked eggs. Annual average hatch success (including nests with zero batching) ranged from 10.6% ± 16.4 to 25.8% ± 24.4 at Babunsanti, and from 52.7% ± 29.7 to 56.0% ± 30.8 at Matapica. Remigrants and non-Surioamese turtles were, on average, larger than new females, and remigrants had a higher clutch frequency. In 6 years, the annual proportion of newly tagged females decreased from 89.9% to 40.5% and that of remigrants increased from 0% to 45.6%. However, the annual proportion of turtles with a nun-Surinamese PIT tag (10.1% to 17.6%) was relatively stable. Combined with the moderate frequency of intra- and interseasonal nesting exchange between regional beaches, this indicates that although the Suriname/French Guiana leatherbacks form a single rookery, individual females show strong nesting fidelity to one side of the Marowijne Estuary. [ABSTRACT FROM AUTHOR]

Observed clutch frequency is the observed number of clutches deposited by a female turtle in a single nesting season. This value is generally biased compared to the true nest number because some clutches could have been missed by beach patrols. We constructed an analytical model to search for the distribution of observed clutch frequency according to 1) the distribution of the clutch number per female, 2) the probability of female capture on the beach, and 3) the probability that a female was an intraseasonal one-time nester. We used data from 1987 to 2003 collected on leatherbacks nesting on Yalimapo beach in French Guiana to test the power of the model. Whereas for 13 of the 16 years, the model produced estimates concurrent with the held data; for the other 3 years, there was no concordance, indicating a lack of power of the model. We describe a required level of capture effect off the beach that will be sufficient for the model to adequately describe clutch frequency across the nesting season. This level is the product of the proportion of the season monitored times the instantaneous probability of the presence and the detection for a particular female during 1 nesting event. [ABSTRACT FROM AUTHOR]

A group of researchers, managers, and tribal leaders with extensive local knowledge from Papua New Guinea, Solomon Islands, Vanuatu, and Papua, Indonesia, provided new information on the status of leatherback nesting populations in the western Pacific Ocean. Twenty-eight nesting sites were identified, of which 21 were previously unknown or poorly described. Although data are still incomplete, we estimate a total of ca. 5000-9200 nests currently laid each year among these 28 sites, with approximately 75% of this nesting activity concentrated at 4 sites along the northwest coast (Bird's Head Peninsula) of Papua, Indonesia. Genetic analysis by using mitochondrial deoxyribonucleic acid sequences identified a total of 6 haplutypes among the 106 samples analyzed for Solomon Islands, Papua, and Papua New Guinea, including a unique common haplotype that is only found in these western Pacific populations. There was no significant difference in haplotype frequencies among these rookeries, which suggests that they represent a metapopulation composed of a single genetic stock. Further work is needed to define the demographic structure within this metapopulation. [ABSTRACT FROM AUTHOR]

The northwest coast of the province of Papua in Indonesia is thought to host the largest remaining leatherback nesting population in the Pacific Ocean. We conducted a census of nesting activity at Jamursba-Medi from 2001 through 2004 and of Wermon from 2002 to 2004, and tracked internesting movements of female leatherbacks by using satellite telemetry during the nesting season in 2003. We recorded 1865-3601 nests each season at Jamursba-Medi and 1788- 2881 nests at Wermon. Nesting occurred year-round, with a peak in activity between May and September at Jamursba-Medi, and between October and March at Wermon. Comparing these data with previous records of nesting activity from 1981 to 2001 indicates that, although there are indications of a long-term decline, this population has not been depleted to the extent found at other major rookeries in the Pacific. Satellite telemetry indicates that nesters frequent waters around the Raja Ampat Islands and coastal waters to the west of Jamursba-Medi, and may also nest outside the monitored area. We recommend establishing a marine protected area to ensure protection of this population in these critical nearshore marine habitats and implementation of conservation measures in partnership with local communities at these nesting beaches before this population becomes depleted. [ABSTRACT FROM AUTHOR]

In Brazil, the only area where regular leatherback sea turtle (Dermochelys coriacea) nesting is known to occur is located on the northern coast of the state of Espírito Santo, around latitude 19°S. In this study, we present the field methods used by Projeto TAMAR-IBAMA (the Brazilian Sea Turtle Conservation Program) in the state of Espírito Santo and analyze data on leatherback nesting from 1988-1989 to 2003-2004. In that period, 527 nests were observed in the study area. The annual number of nests varied between 6 (in 1993-1994) and 92 (in 2002-2003). Between 1995-1996 and 2003-2004, the annual number of nests increased at about 20.4% per year on average. Among the 527 clutches observed, 358 (67.9%) were left in situ, 50 (9.5%) were relocated to another spot on the beach, 88 (16.7%) were relocated to open-air beach hatcheries. and 31 clutches (5.9%) did not have their management decision recorded. Curved carapace length of nesting females was in the range of 139-182 cm (mean = 159.8 cm). At present, there is no significant alteration of the nesting habitat in Espírito Santo, egg poaching has been reduced to very Ion levels, and there is no subsistence hunting for sea turtles of any species. The main challenges to leatherback conservation currently are the incidental capture in artisanal fisheries operating close to nesting beaches and in high seas fisheries operating in the South Atlantic, as well as activities related to the oil industry. An overview of Projeto TAMAR's actions addressing current sea turtle conservation issues in the State of Espírito Santo is presented. [ABSTRACT FROM AUTHOR]

To assess the impact of nest covering on a leatherback turtle Dermochelys coriacea nesting beach in French Guiana, we used field study data and a modelling approach. Field results showed that the covering of a pre-existing nest by a new one causes the destruction of the older nest under some conditions of time and covering area, and almost always causes the destruction of the new nest. We then used field results to parameterize a theoretical model of the nesting beach. This allowed us to obtain a ‘critical carrying capacity for the beach’: the number of nests deposited for which the number of successful nests is maximum; when this number increases, the number of successful nests decreases. With these results, we then concluded that density-dependent nest destruction plays a role in the functioning of the nesting beach. These results are essential for our understanding of nest-site selection at the scale of the beach and its consequences. [ABSTRACT FROM AUTHOR]