The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Frank V Paladino - One of the best experts on this subject based on the ideXlab platform.
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depth of the drying front and temperature affect emergence of Leatherback Turtle hatchlings from the nest
Marine Biology, 2018Co-Authors: Jennifer Swiggs, James R. Spotila, Frank V Paladino, Pilar Santidrian TomilloAbstract:Sea Turtles bury their eggs in nests at depths ranging from 25 to 100 cm. After hatching, Turtles crawl up to the surface and emerge over several days. Some hatchlings fail to emerge and die in the sand column. In this study, we investigated the effect of the depth of the drying front (the region separating saturated and partially dry sand), number of hatchlings emerging, depth of nest and temperature on the emergence of hatchling Leatherback Turtles (Dermochelys coriacea) over the course of three nesting seasons (2008–2009, 2011–2012 and 2012–2013) at Playa Grande, Costa Rica. The depth of the drying front affected the number of hatchlings that failed to emerge in all years and high temperature reduced emergence rate in 2008–2009 and 2012–2013, but not in 2011–2012. Most of the variability in emergence rate was explained by the number of hatchlings emerging and the depth of the drying front. The number of dead hatchlings was mainly explained by the depth of the drying front and temperature. Depth zones within the sand column that included the drying front and the egg chamber registered the greatest number of dead hatchlings. The depth of the drying front, temperature and number of hatchlings remaining in the sand column increased and the emergence rate decreased as the season progressed. Leatherback Turtles are critically endangered in the eastern Pacific Ocean. Conservation strategies towards improving the conditions in the nest environment (i.e. nest irrigation and shading to decrease the depth of the drying front and temperature) could boost hatchling production and contribute to revert declining population trends.
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assortative epibiosis of Leatherback olive ridley and green sea Turtles in the eastern tropical pacific
Journal of the Marine Biological Association of the United Kingdom, 2017Co-Authors: Nathan J. Robinson, Frank V Paladino, John D. Zardus, Eric A Lazowasem, Theodora PinouAbstract: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.
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Scanning Electron Microscope images of epibiotic diatoms found on Leatherback, loggerhead, and olive ridley sea Turtles.
2016Co-Authors: Nathan J. Robinson, Frank V Paladino, Roksana Majewska, Eric A. Lazo-wasem, Ronel Nel, Lourdes Rojas, John D. Zardus, Theodora PinouAbstract:Leatherback Turtle: A = Navicula sp., B, C, and D = Tursiocola sp.; Loggerhead Turtle: E: Amphora sp. 4, F = Amphora sp. 5, G = Amphora sp. 6, H = Amphora sp. 7, I = Diploneis sp. and other adnate unknown diatom; Olive ridley Turtle: J = Nitzschia sp., K = broken pieces of Achnanthes sp (upper left) and possibly other diatom species (arrow), L = Achnanthes sp., M = Poulinea sp. 3, N = Amphora sp. 5, O = Achnanthes sp. All scale bars are 10 μm.
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high beach temperatures increased female biased primary sex ratios but reduced output of female hatchlings in the Leatherback Turtle
Biological Conservation, 2014Co-Authors: Pilar Santidrian Tomillo, Frank V Paladino, Annette E. Sieg, Daniel Oro, Rotney Piedra, James R. SpotilaAbstract:Abstract Sex of offspring in most Turtles is determined by temperature-dependent sex determination (TSD). In sea Turtles, higher incubation temperatures produce female hatchlings and primary sex ratios are often highly female-biased. Because of the current rate of climate warming, highly female-biased sex ratios have raised concern among scientists and managers because populations might become too female biased for genetic viability. We tested the effects of higher incubation temperatures on embryo and hatchling mortality and on sex ratios in a population of Leatherback Turtles (Dermochelys coriacea) in the eastern Pacific. The long-term study provided a large sample size in a location influenced by El Nino Southern Oscillation that resulted in highly variable climatic conditions between seasons. High temperatures reduced emergence success. Output of female hatchlings increased with incubation temperature as it reached the upper end of the transitional range (range of temperatures that produce both sexes) (30 °C) and decreased afterwards because high temperatures increased mortality of ‘female clutches’. Effect of temperature on female hatchling output lessened female-biased sex ratios from 85% female primary sex ratios to 79% secondary sex ratios (sex ratios of total number of hatchlings emerged). If male Turtles reproduce more often than females, operational sex ratios will be closer to 1:1. Female-biased primary sex ratios should not raise concerns by default, but climate change may still threaten populations by reducing hatchling output and increasing frequency of seasons with 100% female production. Clutch relocation to cooler conditions may alter sex ratios and should be used cautiously unless temperatures are so high that no hatchlings survive. In addition, it is unknown what differential survival of male versus female hatchlings may have on the eventual adult sex ratio after they enter the ocean and disperse.
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identification of distinct movement patterns in pacific Leatherback Turtle populations influenced by ocean conditions
Ecological Applications, 2012Co-Authors: Scott R. Benson, Peter H. Dutton, Frank V Paladino, George L Shillinger, Steven J Bograd, Helen Bailey, Scott A Eckert, Stephen J Morreale, Tomoharu EguchiAbstract:Interactions with fisheries are believed to be a major cause of mortality for adult Leatherback Turtles (Dermochelys coriacea), which is of particular concern in the Pacific Ocean, where they have been rapidly declining. In order to identify where these interactions are occurring and how they may be reduced, it is essential first to understand the movements and behavior of Leatherback Turtles. There are two regional nesting populations in the East Pacific (EP) and West Pacific (WP), comprising multiple nesting sites. We synthesized tracking data from the two populations and compared their movement patterns. A switching state-space model was applied to 135 Argos satellite tracks to account for observation error, and to distinguish between migratory and area-restricted search behaviors. The tracking data, from the largest Leatherback data set ever assembled, indicated that there was a high degree of spatial segregation between EP and WP Leatherbacks. Area-restricted search behavior mainly occurred in the southeast Pacific for the EP Leatherbacks, whereas the WP Leatherbacks had several different search areas in the California Current, central North Pacific, South China Sea, off eastern Indonesia, and off southeastern Australia. We also extracted remotely sensed oceanographic data and applied a generalized linear mixed model to determine if Leatherbacks exhibited different behavior in relation to environmental variables. For the WP population, the probability of area-restricted search behavior was positively correlated with chlorophyll-a concentration. This response was less strong in the EP population, but these Turtles had a higher probability of search behavior where there was greater Ekman upwelling, which may increase the transport of nutrients and consequently prey availability. These divergent responses to oceanographic conditions have implications for Leatherback vulnerability to fisheries interactions and to the effects of climate change. The occurrence of Leatherback Turtles within both coastal and pelagic areas means they have a high risk of exposure to many different fisheries, which may be very distant from their nesting sites. The EP Leatherbacks have more limited foraging grounds than the WP Leatherbacks, which could make them more susceptible to any temperature or prey changes that occur in response to climate change.
James R. Spotila - One of the best experts on this subject based on the ideXlab platform.
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depth of the drying front and temperature affect emergence of Leatherback Turtle hatchlings from the nest
Marine Biology, 2018Co-Authors: Jennifer Swiggs, James R. Spotila, Frank V Paladino, Pilar Santidrian TomilloAbstract:Sea Turtles bury their eggs in nests at depths ranging from 25 to 100 cm. After hatching, Turtles crawl up to the surface and emerge over several days. Some hatchlings fail to emerge and die in the sand column. In this study, we investigated the effect of the depth of the drying front (the region separating saturated and partially dry sand), number of hatchlings emerging, depth of nest and temperature on the emergence of hatchling Leatherback Turtles (Dermochelys coriacea) over the course of three nesting seasons (2008–2009, 2011–2012 and 2012–2013) at Playa Grande, Costa Rica. The depth of the drying front affected the number of hatchlings that failed to emerge in all years and high temperature reduced emergence rate in 2008–2009 and 2012–2013, but not in 2011–2012. Most of the variability in emergence rate was explained by the number of hatchlings emerging and the depth of the drying front. The number of dead hatchlings was mainly explained by the depth of the drying front and temperature. Depth zones within the sand column that included the drying front and the egg chamber registered the greatest number of dead hatchlings. The depth of the drying front, temperature and number of hatchlings remaining in the sand column increased and the emergence rate decreased as the season progressed. Leatherback Turtles are critically endangered in the eastern Pacific Ocean. Conservation strategies towards improving the conditions in the nest environment (i.e. nest irrigation and shading to decrease the depth of the drying front and temperature) could boost hatchling production and contribute to revert declining population trends.
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high beach temperatures increased female biased primary sex ratios but reduced output of female hatchlings in the Leatherback Turtle
Biological Conservation, 2014Co-Authors: Pilar Santidrian Tomillo, Frank V Paladino, Annette E. Sieg, Daniel Oro, Rotney Piedra, James R. SpotilaAbstract:Abstract Sex of offspring in most Turtles is determined by temperature-dependent sex determination (TSD). In sea Turtles, higher incubation temperatures produce female hatchlings and primary sex ratios are often highly female-biased. Because of the current rate of climate warming, highly female-biased sex ratios have raised concern among scientists and managers because populations might become too female biased for genetic viability. We tested the effects of higher incubation temperatures on embryo and hatchling mortality and on sex ratios in a population of Leatherback Turtles (Dermochelys coriacea) in the eastern Pacific. The long-term study provided a large sample size in a location influenced by El Nino Southern Oscillation that resulted in highly variable climatic conditions between seasons. High temperatures reduced emergence success. Output of female hatchlings increased with incubation temperature as it reached the upper end of the transitional range (range of temperatures that produce both sexes) (30 °C) and decreased afterwards because high temperatures increased mortality of ‘female clutches’. Effect of temperature on female hatchling output lessened female-biased sex ratios from 85% female primary sex ratios to 79% secondary sex ratios (sex ratios of total number of hatchlings emerged). If male Turtles reproduce more often than females, operational sex ratios will be closer to 1:1. Female-biased primary sex ratios should not raise concerns by default, but climate change may still threaten populations by reducing hatchling output and increasing frequency of seasons with 100% female production. Clutch relocation to cooler conditions may alter sex ratios and should be used cautiously unless temperatures are so high that no hatchlings survive. In addition, it is unknown what differential survival of male versus female hatchlings may have on the eventual adult sex ratio after they enter the ocean and disperse.
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on the dispersal of Leatherback Turtle hatchlings from mesoamerican nesting beaches
Proceedings of The Royal Society B: Biological Sciences, 2012Co-Authors: George L Shillinger, Elliott L Hazen, Steven J Bograd, Helen Bailey, Emanuele Di Lorenzo, Hao Luo, James R. SpotilaAbstract:So little is known about the early life history of Leatherback Turtles (Dermochelys coriacea )f rom hatchling to adulthood that this period has been termed the ‘lost years’. For critically endangered eastern Pacific Leatherback populations, continued and rapid declines underscore the urgent need to develop conservation strategies across all life stages. We investigate Leatherback hatchling dispersal from four Mesoamerican nesting beaches using passive tracer experiments within a regional ocean modelling system. The evolution of tracer distribution from each of the nesting beaches showed the strong influence of eddy transport and coastal currents. Modelled hatchlings from Playa Grande, Costa Rica, were most likely to be entrained and transported offshore by large-scale eddies coincident with the peak Leatherback nesting and hatchling emergence period. These eddies potentially serve as ‘hatchling highways’, providing a means of rapid offshore transport away from predation and a productive refuge within which newly hatched Turtles can develop. We hypothesize that the most important Leatherback nesting beach remaining in the eastern Pacific (Playa Grande) has been evolutionarily selected as an optimal nesting site owing to favourable ocean currents that enhance hatchling survival.
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potentially lethal bacteria in Leatherback Turtle eggs in the wild threaten both Turtles and conservationists
Journal of Experimental Marine Biology and Ecology, 2011Co-Authors: Gerald Soslau, James R. Spotila, Adam Chun, Kathryn T WeberAbstract:Abstract The Leatherback Turtle is an endangered sea Turtle whose numbers are in decline. There is a great effort world wide on the part of many conservationists to protect these Turtles and their eggs. We previously demonstrated that blood from a Leatherback hatchling was infected with a hemolytic acinetobacter bacterium, Acinetobacter sp. HM 746599, implying that the developing embryo may have been infected in the egg. Only about 50% of the eggs laid on a Costa Rican beach hatch due to predation, inundation and within nest factors. This study was conducted to determine whether high bacterial infection rate of eggs incubating in the dark, moist sands of the beach contributes to the low hatching rate. Samples were taken aseptically from adult cloacal fluids and failed and opened eggs in search of potentially lethal bacteria. We identified three bacterial species in selected cloned samples that exhibited hemolytic activity. These bacteria were species of the Bacillus, Pseudomonas and Aeromonas genera. Many of these bacterial species are known pathogens to humans and may account for developmental arrest of the Turtle embryo. These bacterial species may also pose a danger to human workers who come in contact with them. Knowledge of the bacteria that can infect and possibly kill Leatherback embryos may lead to treatment modalities of Leatherback clutches with anti-microbial agents which would allow us to improve the hatching rates of these animals under controlled conditions.
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acinetobacter sp hm746599 isolated from Leatherback Turtle blood
Fems Microbiology Letters, 2011Co-Authors: Gerald Soslau, James R. Spotila, Jacob A Russell, Andrew J Mathew, Pamela BagsiyaoAbstract:A newly described bacterial isolate, Acinetobacter sp. HM746599, has been obtained from Leatherback sea Turtle hatchling blood. The implication is that the hatchling was infected during development in the egg, which is substantiated by other studies to be reported by us in the future. The 16S rRNA gene sequence of the bacterium (GenBank accession number: HM746599) showed the greatest similarity to the identified species, Acinetobacter beijerinckii (97.6-99.78%) and Acinetobacter venetianus (99.78%). Acinetobacter sp. HM746599 are gram-negative, rod-shaped coccobacilli and are hemolytic/cytotoxic to human and sea Turtle red blood cells (RBCs). Hemolysis is not the result of any detectable soluble toxin. Acinetobacter beijerinckii and A. venetianus hemolyze sheep RBCs while Acinetobacter sp. HM746599 does not, and unlike A. venetianus, the growth of Acinetobacter sp. HM746599 and A. beijerinckii is not supported by l-arginine. Many Acinetobacter species, especially hemolytic ones, are pathogenic to immunologically compromised humans and it is possible that, in addition to sea Turtles, this bacterium might also be a danger to susceptible humans who handle infected hatchlings. The bacteria are available from CCUG (Culture Collection, University Gothenburg, Goteborg, Sweden) and from NRRL (Agricultural Research Service Culture Collection, Peoria, IL).
Jean-yves Georges - One of the best experts on this subject based on the ideXlab platform.
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Leatherback Turtles are capital breeders morphometric and physiological evidence from longitudinal monitoring
Physiological and Biochemical Zoology, 2013Co-Authors: Virginie Plot, Thomas Jenkins, Sabrina Fossette, Jean-yves Georges, Jeanpatrice RobinAbstract:AbstractOrganisms compensate for reproduction costs through two major strategies: capital breeders store body reserves before reproduction and do not feed during the breeding season, whereas income breeders adjust their food intake depending on concurrent reproductive needs. Sea Turtles are commonly considered capital breeders. Yet recent biometric and behavioral studies have suggested that sea Turtles may in fact feed during reproduction. We tested this hypothesis in the Leatherback Turtle Dermochelys coriacea, nesting in French Guiana. Our study is based on the innovative use of longitudinal monitoring for morphological (body size, body mass, and body condition) and physiological (plasma glucose, triacylglycerides, urea, calcium, and hematocrit) measurements in 35 females throughout the 2006 nesting season. During their 71-d nesting period, Leatherbacks lost a mean (±SE) of kg (i.e., ∼11% of their initial body mass of kg). Simultaneously, a significant decrease in plasma concentrations of glucose, triac...
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telomeres age and reproduction in a long lived reptile
PLOS ONE, 2012Co-Authors: Virginie Plot, Jean-yves Georges, Francois Criscuolo, Sandrine ZahnAbstract:A major interest has recently emerged in understanding how telomere shortening, mechanism triggering cell senescence, is linked to organism ageing and life history traits in wild species. However, the links between telomere length and key history traits such as reproductive performances have received little attention and remain unclear to date. The Leatherback Turtle Dermochelys coriacea is a long-lived species showing rapid growth at early stages of life, one of the highest reproductive outputs observed in vertebrates and a dichotomised reproductive pattern related to migrations lasting 2 or 3 years, supposedly associated with different environmental conditions. Here we tested the prediction of blood telomere shortening with age in this species and investigated the relationship between blood telomere length and reproductive performances in Leatherback Turtles nesting in French Guiana. We found that blood telomere length did not differ between hatchlings and adults. The absence of blood telomere shortening with age may be related to an early high telomerase activity. This telomere-restoring enzyme was formerly suggested to be involved in preventing early telomere attrition in early fast-growing and long-lived species, including squamate reptiles. We found that within one nesting cycle, adult females having performed shorter migrations prior to the considered nesting season had shorter blood telomeres and lower reproductive output. We propose that shorter blood telomeres may result from higher oxidative stress in individuals breeding more frequently (i.e., higher costs of reproduction) and/or restoring more quickly their body reserves in cooler feeding areas during preceding migration (i.e., higher foraging costs). This first study on telomeres in the giant Leatherback Turtle suggests that blood telomere length predicts not only survival chances, but also reproductive performances. Telomeres may therefore be a promising new tool to evaluate individual reproductive quality which could be useful in such species of conservation concern.
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movement patterns for a critically endangered species the Leatherback Turtle dermochelys coriacea linked to foraging success and population status
PLOS ONE, 2012Co-Authors: Sabrina Fossette, Jean-yves Georges, Philippe Gaspar, George L Shillinger, Steven J Bograd, Helen Bailey, Alan M Swithenbank, K Patrik H StrombergAbstract:Foraging success for pelagic vertebrates may be revealed by horizontal and vertical movement patterns. We show markedly different patterns for Leatherback Turtles in the North Atlantic versus Eastern Pacific, which feed on gelatinous zooplankton that are only occasionally found in high densities. In the Atlantic, travel speed was characterized by two modes, indicative of high foraging success at low speeds (<15 km d−1) and transit at high speeds (20–45 km d−1). Only a single mode was evident in the Pacific, which occurred at speeds of 21 km d−1 indicative of transit. The mean dive depth was more variable in relation to latitude but closer to the mean annual depth of the thermocline and nutricline for North Atlantic than Eastern Pacific Turtles. The most parsimonious explanation for these findings is that Eastern Pacific Turtles rarely achieve high foraging success. This is the first support for foraging behaviour differences between populations of this critically endangered species and suggests that longer periods searching for prey may be hindering population recovery in the Pacific while aiding population maintenance in the Atlantic.
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Plastic debris in a nesting Leatherback Turtle in French Guiana
Chelonian Conservation and Biology, 2010Co-Authors: Virginie Plot, Jean-yves GeorgesAbstract:We report a field observation of an adult female Leatherback Turtle (Dermochelys coriacea) expulsing 2.6 kg of plastic debris from her cloaca while nesting in French Guiana. This field report sustains concerns about plastic ingestion by this endangered species and, further, the impacts of plastic debris to marine wildlife, and points out the needs for effective waste management in both terrestrial and marine habitats.
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Spatio-temporal foraging patterns of a giant zooplanktivore, the Leatherback Turtle
Journal of Marine Systems, 2010Co-Authors: Sabrina Fossette, Jean-yves Georges, Victoria J. Hobson, Charlotte Girard, Beatriz Calmettes, Philippe Gaspar, Graeme HaysAbstract:Understanding food web functioning through the study of natural bio-indicators may constitute a valuable and original approach. In the context of jellyfish proliferation in many overexploited marine ecosystems studying the spatio-temporal foraging patterns of the giant “jellyvore” Leatherback Turtle turns out to be particularly relevant. Here we analyzed long-term tracking data to assess spatio-temporal foraging patterns in 21 Leatherback Turtles during their pluri-annual migration in the Northern Atlantic. Through an analytical approach based on the animal's own motion (independent of currents) and diving behavior distinct zones of high and low foraging success were identified. High foraging success occurred in a sub-equatorial zone spanning the width of the Atlantic and at high (>30°N) latitudes. Between these zones in the centre of North Atlantic gyre there was low foraging success. This “ocean desert” area was traversed at high speed by Leatherbacks on their way to more productive areas at higher latitudes. Animals traveled slowly in high foraging success areas and dived shallower (17.2±8.0 kmday−1 and 53.6±33.1 m mean±SD respectively) than in low foraging success areas (51.0±13.1 kmday−1 and 81.8±56.2 m mean±SD respectively). These spatio-temporal foraging patterns seem to relatively closely match the main features of the integrated mesozooplankton distribution in the North Atlantic. Our method of defining high foraging success areas is intuitive and relatively easy to implement but also takes into account the impact of oceanic currents on animal's behavior.
Sabrina Fossette - One of the best experts on this subject based on the ideXlab platform.
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climate change impacts on Leatherback Turtle pelagic habitat in the southeast pacific
Deep-sea Research Part Ii-topical Studies in Oceanography, 2015Co-Authors: Ellen Willisnorton, Sabrina Fossette, David G Foley, Elliott L Hazen, George L Shillinger, Ryan R Rykaczewski, John P Dunne, Steven J BogradAbstract:Abstract Eastern Pacific populations of the Leatherback Turtle ( Dermochelys coriacea ) have declined by over 90% during the past three decades. The decline is primarily attributed to human pressures, including unsustainable egg harvest, development on nesting beaches, and by-catch mortality. In particular, the effects of climate change may impose additional stresses upon already threatened Leatherback populations. This study analyzes how the pelagic habitat of Eastern Pacific Leatherbacks may be affected by climate change over the next century. This population adheres to a persistent migration pattern; following nesting at Playa Grande, Costa Rica, individuals move rapidly through equatorial currents and into foraging habitat within the oligotrophic South Pacific Gyre. Forty-six nesting females were fitted with satellite tags. Based on the Turtle positions, ten environmental variables were sampled along the tracks. Presence/absence habitat models were created to determine the oceanographic characteristics of the preferred Turtle habitat. Core pelagic habitat was characterized by relatively low sea surface temperatures and chlorophyll-a. Based on these habitat models, we predicted habitat change using output from the Geophysical Fluid Dynamics Laboratory prototype Earth System Model under the Special Report on Emissions Scenario A2 (business-as-usual). Although the model predicted both habitat losses and gains throughout the region, we estimated that overall the core pelagic habitat of the Eastern Pacific Leatherback population will decline by approximately 15% within the next century. This habitat modification might increase pressure on a critically endangered population, possibly forcing distributional shifts, behavioral changes, or even extinction.
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pan atlantic analysis of the overlap of a highly migratory species the Leatherback Turtle with pelagic longline fisheries
Proceedings of The Royal Society B: Biological Sciences, 2014Co-Authors: Sabrina Fossette, Annette C Broderick, Michael S Coyne, Matthew J Witt, Peter I Miller, M A Nalovic, Diego Albareda, A P Almeida, D Chaconchaverri, Aloysius DomingoAbstract:Large oceanic migrants play important roles in ecosystems, yet many species are of conservation concern as a result of anthropogenic threats, of which incidental capture by fisheries is frequently identified. The last large populations of the Leatherback Turtle, Dermochelys coriacea, occur in the Atlantic Ocean, but interactions with industrial fisheries could jeopardize recent positive population trends, making bycatch mitigation a priority. Here, we perform the first pan-Atlantic analysis of spatio-temporal distribution of the Leatherback Turtle and ascertain overlap with longline fishing effort. Data suggest that the Atlantic probably consists of two regional management units: northern and southern (the latter including Turtles breeding in South Africa). Although Turtles and fisheries show highly diverse distributions, we highlight nine areas of high susceptibility to potential bycatch (four in the northern Atlantic and five in the southern/equatorial Atlantic) that are worthy of further targeted investigation and mitigation. These are reinforced by reports of Leatherback bycatch at eight of these sites. International collaborative efforts are needed, especially from nations hosting regions where susceptibility to bycatch is likely to be high within their exclusive economic zone (northern Atlantic: Cape Verde, Gambia, Guinea Bissau, Mauritania, Senegal, Spain, USA and Western Sahara; southern Atlantic: Angola, Brazil, Namibia and UK) and from nations fishing in these high-susceptibility areas, including those located in international waters.
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Leatherback Turtles are capital breeders morphometric and physiological evidence from longitudinal monitoring
Physiological and Biochemical Zoology, 2013Co-Authors: Virginie Plot, Thomas Jenkins, Sabrina Fossette, Jean-yves Georges, Jeanpatrice RobinAbstract:AbstractOrganisms compensate for reproduction costs through two major strategies: capital breeders store body reserves before reproduction and do not feed during the breeding season, whereas income breeders adjust their food intake depending on concurrent reproductive needs. Sea Turtles are commonly considered capital breeders. Yet recent biometric and behavioral studies have suggested that sea Turtles may in fact feed during reproduction. We tested this hypothesis in the Leatherback Turtle Dermochelys coriacea, nesting in French Guiana. Our study is based on the innovative use of longitudinal monitoring for morphological (body size, body mass, and body condition) and physiological (plasma glucose, triacylglycerides, urea, calcium, and hematocrit) measurements in 35 females throughout the 2006 nesting season. During their 71-d nesting period, Leatherbacks lost a mean (±SE) of kg (i.e., ∼11% of their initial body mass of kg). Simultaneously, a significant decrease in plasma concentrations of glucose, triac...
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does prey size matter novel observations of feeding in the Leatherback Turtle dermochelys coriacea allow a test of predator prey size relationships
Biology Letters, 2012Co-Authors: Sabrina Fossette, James P Casey, Adrian C Gleiss, Andrew R Lewis, Graeme C HaysAbstract:Optimal foraging models predict that large predators should concentrate on large prey in order to maximize their net gain of energy intake. Here, we show that the largest species of sea Turtle, Dermochelys coriacea, does not strictly adhere to this general pattern. Field observations combined with a theoretical model suggest that a 300 kg Leatherback Turtle would meet its energetic requirements by feeding for 3–4 h a day on 4 g jellyfish, but only if prey were aggregated in high-density patches. Therefore, prey abundance rather than prey size may, in some cases, be the overriding parameter for foraging Leatherbacks. This is a classic example where the presence of small prey in the diet of a large marine predator may reflect profitable foraging decisions if the relatively low energy intake per small individual prey is offset by high encounter rates and minimal capture and handling costs. This study provides, to our knowledge, the first quantitative estimates of intake rate for this species.
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movement patterns for a critically endangered species the Leatherback Turtle dermochelys coriacea linked to foraging success and population status
PLOS ONE, 2012Co-Authors: Sabrina Fossette, Jean-yves Georges, Philippe Gaspar, George L Shillinger, Steven J Bograd, Helen Bailey, Alan M Swithenbank, K Patrik H StrombergAbstract:Foraging success for pelagic vertebrates may be revealed by horizontal and vertical movement patterns. We show markedly different patterns for Leatherback Turtles in the North Atlantic versus Eastern Pacific, which feed on gelatinous zooplankton that are only occasionally found in high densities. In the Atlantic, travel speed was characterized by two modes, indicative of high foraging success at low speeds (<15 km d−1) and transit at high speeds (20–45 km d−1). Only a single mode was evident in the Pacific, which occurred at speeds of 21 km d−1 indicative of transit. The mean dive depth was more variable in relation to latitude but closer to the mean annual depth of the thermocline and nutricline for North Atlantic than Eastern Pacific Turtles. The most parsimonious explanation for these findings is that Eastern Pacific Turtles rarely achieve high foraging success. This is the first support for foraging behaviour differences between populations of this critically endangered species and suggests that longer periods searching for prey may be hindering population recovery in the Pacific while aiding population maintenance in the Atlantic.
Steven J Bograd - One of the best experts on this subject based on the ideXlab platform.
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climate change impacts on Leatherback Turtle pelagic habitat in the southeast pacific
Deep-sea Research Part Ii-topical Studies in Oceanography, 2015Co-Authors: Ellen Willisnorton, Sabrina Fossette, David G Foley, Elliott L Hazen, George L Shillinger, Ryan R Rykaczewski, John P Dunne, Steven J BogradAbstract:Abstract Eastern Pacific populations of the Leatherback Turtle ( Dermochelys coriacea ) have declined by over 90% during the past three decades. The decline is primarily attributed to human pressures, including unsustainable egg harvest, development on nesting beaches, and by-catch mortality. In particular, the effects of climate change may impose additional stresses upon already threatened Leatherback populations. This study analyzes how the pelagic habitat of Eastern Pacific Leatherbacks may be affected by climate change over the next century. This population adheres to a persistent migration pattern; following nesting at Playa Grande, Costa Rica, individuals move rapidly through equatorial currents and into foraging habitat within the oligotrophic South Pacific Gyre. Forty-six nesting females were fitted with satellite tags. Based on the Turtle positions, ten environmental variables were sampled along the tracks. Presence/absence habitat models were created to determine the oceanographic characteristics of the preferred Turtle habitat. Core pelagic habitat was characterized by relatively low sea surface temperatures and chlorophyll-a. Based on these habitat models, we predicted habitat change using output from the Geophysical Fluid Dynamics Laboratory prototype Earth System Model under the Special Report on Emissions Scenario A2 (business-as-usual). Although the model predicted both habitat losses and gains throughout the region, we estimated that overall the core pelagic habitat of the Eastern Pacific Leatherback population will decline by approximately 15% within the next century. This habitat modification might increase pressure on a critically endangered population, possibly forcing distributional shifts, behavioral changes, or even extinction.
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on the dispersal of Leatherback Turtle hatchlings from mesoamerican nesting beaches
Proceedings of The Royal Society B: Biological Sciences, 2012Co-Authors: George L Shillinger, Elliott L Hazen, Steven J Bograd, Helen Bailey, Emanuele Di Lorenzo, Hao Luo, James R. SpotilaAbstract:So little is known about the early life history of Leatherback Turtles (Dermochelys coriacea )f rom hatchling to adulthood that this period has been termed the ‘lost years’. For critically endangered eastern Pacific Leatherback populations, continued and rapid declines underscore the urgent need to develop conservation strategies across all life stages. We investigate Leatherback hatchling dispersal from four Mesoamerican nesting beaches using passive tracer experiments within a regional ocean modelling system. The evolution of tracer distribution from each of the nesting beaches showed the strong influence of eddy transport and coastal currents. Modelled hatchlings from Playa Grande, Costa Rica, were most likely to be entrained and transported offshore by large-scale eddies coincident with the peak Leatherback nesting and hatchling emergence period. These eddies potentially serve as ‘hatchling highways’, providing a means of rapid offshore transport away from predation and a productive refuge within which newly hatched Turtles can develop. We hypothesize that the most important Leatherback nesting beach remaining in the eastern Pacific (Playa Grande) has been evolutionarily selected as an optimal nesting site owing to favourable ocean currents that enhance hatchling survival.
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movement patterns for a critically endangered species the Leatherback Turtle dermochelys coriacea linked to foraging success and population status
PLOS ONE, 2012Co-Authors: Sabrina Fossette, Jean-yves Georges, Philippe Gaspar, George L Shillinger, Steven J Bograd, Helen Bailey, Alan M Swithenbank, K Patrik H StrombergAbstract:Foraging success for pelagic vertebrates may be revealed by horizontal and vertical movement patterns. We show markedly different patterns for Leatherback Turtles in the North Atlantic versus Eastern Pacific, which feed on gelatinous zooplankton that are only occasionally found in high densities. In the Atlantic, travel speed was characterized by two modes, indicative of high foraging success at low speeds (<15 km d−1) and transit at high speeds (20–45 km d−1). Only a single mode was evident in the Pacific, which occurred at speeds of 21 km d−1 indicative of transit. The mean dive depth was more variable in relation to latitude but closer to the mean annual depth of the thermocline and nutricline for North Atlantic than Eastern Pacific Turtles. The most parsimonious explanation for these findings is that Eastern Pacific Turtles rarely achieve high foraging success. This is the first support for foraging behaviour differences between populations of this critically endangered species and suggests that longer periods searching for prey may be hindering population recovery in the Pacific while aiding population maintenance in the Atlantic.
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identification of distinct movement patterns in pacific Leatherback Turtle populations influenced by ocean conditions
Ecological Applications, 2012Co-Authors: Scott R. Benson, Peter H. Dutton, Frank V Paladino, George L Shillinger, Steven J Bograd, Helen Bailey, Scott A Eckert, Stephen J Morreale, Tomoharu EguchiAbstract:Interactions with fisheries are believed to be a major cause of mortality for adult Leatherback Turtles (Dermochelys coriacea), which is of particular concern in the Pacific Ocean, where they have been rapidly declining. In order to identify where these interactions are occurring and how they may be reduced, it is essential first to understand the movements and behavior of Leatherback Turtles. There are two regional nesting populations in the East Pacific (EP) and West Pacific (WP), comprising multiple nesting sites. We synthesized tracking data from the two populations and compared their movement patterns. A switching state-space model was applied to 135 Argos satellite tracks to account for observation error, and to distinguish between migratory and area-restricted search behaviors. The tracking data, from the largest Leatherback data set ever assembled, indicated that there was a high degree of spatial segregation between EP and WP Leatherbacks. Area-restricted search behavior mainly occurred in the southeast Pacific for the EP Leatherbacks, whereas the WP Leatherbacks had several different search areas in the California Current, central North Pacific, South China Sea, off eastern Indonesia, and off southeastern Australia. We also extracted remotely sensed oceanographic data and applied a generalized linear mixed model to determine if Leatherbacks exhibited different behavior in relation to environmental variables. For the WP population, the probability of area-restricted search behavior was positively correlated with chlorophyll-a concentration. This response was less strong in the EP population, but these Turtles had a higher probability of search behavior where there was greater Ekman upwelling, which may increase the transport of nutrients and consequently prey availability. These divergent responses to oceanographic conditions have implications for Leatherback vulnerability to fisheries interactions and to the effects of climate change. The occurrence of Leatherback Turtles within both coastal and pelagic areas means they have a high risk of exposure to many different fisheries, which may be very distant from their nesting sites. The EP Leatherbacks have more limited foraging grounds than the WP Leatherbacks, which could make them more susceptible to any temperature or prey changes that occur in response to climate change.
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persistent Leatherback Turtle migrations present opportunities for conservation
PLOS Biology, 2008Co-Authors: George L Shillinger, Bryan P. Wallace, James R. Spotila, Philippe Gaspar, Steven J Bograd, Daniel M Palacios, Helen Bailey, Alan M Swithenbank, Frank V PaladinoAbstract:Effective transboundary conservation of highly migratory marine animals requires international management cooperation as well as clear scientific information about habitat use by these species. Populations of Leatherback Turtles (Dermochelys coriacea) in the eastern Pacific have declined by .90% during the past two decades, primarily due to unsustainable egg harvest and fisheries bycatch mortality. While research and conservation efforts on nesting beaches are ongoing, relatively little is known about this population of Leatherbacks’ oceanic habitat use and migration pathways. We present the largest multi-year (2004–2005, 2005–2006, and 2007) satellite tracking dataset (12,095 cumulative satellite tracking days) collected for Leatherback Turtles. Forty-six females were electronically tagged during three field seasons at Playa Grande, Costa Rica, the largest extant nesting colony in the eastern Pacific. After completing nesting, the Turtles headed southward, traversing the dynamic equatorial currents with rapid, directed movements. In contrast to the highly varied dispersal patterns seen in many other sea Turtle populations, Leatherbacks from Playa Grande traveled within a persistent migration corridor from Costa Rica, past the equator, and into the South Pacific Gyre, a vast, low-energy, low-productivity region. We describe the predictable effects of ocean currents on a Leatherback migration corridor and characterize long-distance movements by the Turtles in the eastern South Pacific. These data from high seas habitats will also elucidate potential areas for mitigating fisheries bycatch interactions. These findings directly inform existing multinational conservation frameworks and provide immediate regions in the migration corridor where conservation can be implemented. We identify high seas locations for focusing future conservation efforts within the Leatherback dispersal zone in the South Pacific Gyre.