Marine Turtle Species Research Articles

Conservation and Enforcement Capacity index (CECi): Integrating human development, economy, and marine turtle status

Human societies are closely linked to their ecological environments. Natural ecosystems and wildlife populations are often in better condition in countries with healthy, educated and economically prosperous populations compared to countries with lower health and literacy conditions, and depressed economies. In the latter countries, these socio-economic factors can compromise government's capacity to manage their natural resources. Thus, the conservation capacity of a government is likely to play key role in the protection of threatened species, such as marine turtles. This paper aims: (1) to evaluate the conservation capacity and enforcement within the 58 Regional Management Units (RMUs) of the seven species of marine turtles throughout the world, and (2) to develop a proxy that predicts the conservation status of RMUs. We developed a Conservation and Enforcement Capacity index (CECi) by integrating the following indices: (a) the economic level and, (b) the Human Development Index (HDI) of each country, plus (c) the risks and threats in the RMUs. We used the conservation status of 15 RMUs recently assessed by the International Union for Conservation of Nature - IUCN to predict the conservation status of the 43 RMUs without updated IUCN categorisation. CECi values ranged from 0 to 1, where lower values represent a better capacity for implementation of conservation initiatives. We found that using our multi-index model, we predicted the status of 33 of 58 RMUs, 57% of which may be of threatened conservation status due to their high CECi values. This study highlighted how socio-economic aspects may impact conservation of endangered species.

When isotopes fail: importance of satellite telemetry and multi-site validation when estimating the foraging grounds of migratory species

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 633:197-206 (2020) - DOI: https://doi.org/10.3354/meps13179 When isotopes fail: importance of satellite telemetry and multi-site validation when estimating the foraging grounds of migratory species O. I. Coffee1,*, D. T. Booth1, J. A. Thia1, C. J. Limpus2 1The University of Queensland, School of Biological Sciences, St Lucia, Queensland 4072, Australia 2Queensland Government, Department of Environment and Science, Aquatic Threatened Species Unit, Dutton Park, Queensland 4102, Australia *Corresponding author: owen.coffee@uq.net.au ABSTRACT: A combination of δ13C and δ15N isotope ratios, capture-mark-recapture and satellite telemetry data were used to investigate the foraging locations supporting nesting loggerhead turtles Caretta caretta on the Woongarra coastline, southeast Queensland, Australia. Known foraging grounds were available for a subset of these turtles and supplemented with samples taken from foraging turtles to determine whether foraging regions could be identified in untracked nesting turtles using the stable isotopic values of their sampled tissue. Despite the large distances between known foraging regions, no latitudinal gradient was observed in the isotopic values of these turtles. In addition, the isotopic values of foraging individuals from a single site encompassed the range of all loggerhead turtles sampled over the 2000 km north-south distribution along the east coast of Australia. This study demonstrates that assumptions common to δ13C and δ15N stable isotope inference in migratory species are not adhered to globally. Contrasting the successes of stable isotope analysis in the northern hemisphere, these results indicate that factors in the southwest Pacific such as differing prevailing oceanic currents, temperature regimes and river run-offs may prevent the establishment of region-specific unique isoscapes needed for identifying the foraging region of turtles using their isotopic values. Therefore, we caution against the use of δ13C and δ15N stable isotopic values as suitable indicators of foraging regions for loggerhead turtles in Australia. These findings potentially highlight the need to re-evaluate when and where the use of isotopic analysis is appropriate for identifying foraging locations in marine turtle species. KEY WORDS: Loggerhead turtles · Caretta caretta · Carbon isotope · Nitrogen isotope · Migration connectivity Full text in pdf format PreviousNextCite this article as: Coffee OI, Booth DT, Thia JA, Limpus CJ (2020) When isotopes fail: importance of satellite telemetry and multi-site validation when estimating the foraging grounds of migratory species. Mar Ecol Prog Ser 633:197-206. https://doi.org/10.3354/meps13179 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 633. Online publication date: January 09, 2020 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2020 Inter-Research.

Assessing coastal artificial light and potential exposure of wildlife at a national scale: the case of marine turtles in Brazil

Coastal areas provide critical nesting habitat for marine turtles. Understanding how artificial light might impact populations is key to guide management strategies. Here we assess the extent to which nesting populations of four marine turtle species—leatherback (Dermochelys coriacea), olive ridley (Lepidochelys olivacea), hawksbill (Eretmochelys imbricata) and two subpopulations of loggerhead (Caretta caretta) turtles—are exposed to light pollution across 604 km of the Brazilian coast. We used yearly night-time satellite images from two 5-year periods (1992–1996 and 2008–2012) from the US Air Force Defense Meteorological Satellite Programme (DMSP) to determine the proportion of nesting areas that are exposed to detectable levels of artificial light and identify how this has changed over time. Over the monitored time-frame, 63.7% of the nesting beaches experienced an increase in night light levels. Based on nest densities, we identified 54 reproductive hotspots: 62.9% were located in areas potentially exposed to light pollution. Light levels appeared to have a significant effect on nest densities of hawksbills and the northern loggerhead turtle stock, however high nest densities were also seen in lit areas. The status of all species/subpopulations has improved across the time period despite increased light levels. These findings suggest that (1) nest site selection is likely primarily determined by variables other than light and (2) conservation strategies in Brazil appear to have been successful in contributing to reducing impacts on nesting beaches. There is, however, the possibility that light also affects hatchlings in coastal waters, and impacts on population recruitment may take longer to fully manifest in nesting numbers. Recommendations are made to further this work to provide deeper insights into the impacts of anthropogenic light on marine turtles.

Predicting multi-species foraging hotspots for marine turtles in the Gulf of Mexico

Quantifying the distribution of animals and identifying underlying characteristics that define suitable habitat are essential for effective conservation of free-ranging species. Prioritizing areas for conservation is important in managing a geographic extent that has a high level of disturbance and limited conservation resources. We examined the potential use of a species distribution model ensemble for multi-species conservation in marine habitats. Using satellite telemetry locations during foraging as input data, and ensemble ecological niche models, we predicted foraging areas for 2 nesting marine turtle species within the Gulf of Mexico (GoM): Kemp’s ridley Lepidochelys kempii (n = 63) and loggerhead Caretta caretta (n = 63). We considered 7 geophysical, biological, and climatic variables and compared contributing factors for each species’ foraging habitat selection. For both species, predicted suitable foraging habitats encompassed large areas along the GoM coast, but only intersected with each other in relatively small areas. Highly parameterized models resulted in overall greater fits, suggesting that multiple factors influence habitat selection by these species. Model validation results were mixed: cross-validation resulted in high prediction accuracy for both species, but an evaluation against independent data resulted in a low omission rate (5%) for Kemp’s ridleys and a high omission rate (72%) for loggerheads. The relatively small intersection of model-predicted foraging areas for these 2 species within the study area may indicate possible niche differentiations. The high omission rate for loggerheads indicates our samples likely underrepresent the population and illustrates the challenges in predicting suitable foraging extents for species that make dynamic movements and have greater individual variability.

A survey of marine turtles found in Davao Oriental, Philippines

Marine turtles are enlisted as critically endangered marine animals vulnerable to extinction. In Mayo Bay, Davao Oriental, the data on marine turtles' status is deficient. Land-based monitoring from 2014 to 2016 was dedicated to filling in the gaps in the knowledge and status of marine turtles in Mayo Bay. Four species, namely, Chelonia mydas, Eretmochelys imbricata, Lepidochelys olivacea, and Dermochelys coriacea, were identified as being present in the bay. Commonly sighted species were Chelonia mydas (n = 121), and the most numbered species accounted for stranding incidences (n = 9), generally due to by-catch using hook and line. Nesting activities recorded Lepidochelys olivacea as the prominent nester, with a total of 5,926 eggs laid and 4,956 eggs hatched and released with a hatching percentage of 84.03%. Chelonia mydas was observed to nest previously in 2014; however, it was found to be inactive after nesting in 2015 and 2016. Mayo Bay is found to be home to four species of marine turtles, although common challenges in conservation efforts are stranding incidences, beach encroachment, and intensive lighting due to resorts in the area. An intensive education campaign drive should be done, and the institutionalization of the protection of marine turtles should also be considered.

Exposure of Marine Turtle Nesting Grounds to Named Storms Along the Continental USA

Named storms can cause substantial impacts on the habitat and reproductive output of threatened species, such as marine turtles. To determine the impacts of named storms on marine turtles and inform management, it is necessary to determine the exposure of marine turtle nesting grounds to recent storm activities. To address this, remote sensing information of named storm tracks coupled with nesting ground data were used to investigate the temporal and spatial overlap between nesting grounds for four species of marine turtles in the continental United States of America. All species of marine turtles were exposed to named storms, with variation in exposure driven by the spatial distribution of each population’s nesting ground, the temporal overlap between the storms and reproductive events, and nest placement on the beach. Loggerhead turtles were the most exposed species to named storms, with the northern management unit having significantly higher exposure levels than all other loggerhead management units. Kemp’s ridley turtles, in contrast, were found to be the least exposed species to named storms. This study establishes a valuable current baseline against which to measure and compare future impacts that result as climate change progresses and storms become more frequent and intense. Importantly, cumulative and synergetic effects from other climatic processes and anthropogenic stressors should be considered in future analysis.

Asmodochelys parhami, a new fossil marine turtle from the Campanian Demopolis Chalk and the stratigraphic congruence of competing marine turtle phylogenies.

Resolving the phylogeny of sea turtles is uniquely challenging given the high potential for the unification of convergent lineages due to systematic homoplasy. Equivocal reconstructions of marine turtle evolution subsequently inhibit efforts to establish fossil calibrations for molecular divergence estimates and prevent the accurate reconciliation of biogeographic or palaeoclimatic data with phylogenetic hypotheses. Here we describe a new genus and species of marine turtle, Asmodochelys parhami, from the Upper Campanian Demopolis Chalk of Alabama and Mississippi, USA represented by three partial shells. Phylogenetic analysis shows that A. parhami belongs to the ctenochelyids, an extinct group that shares characteristics with both pan-chelonioids and pan-cheloniids. In addition to supporting Ctenochelyidae as a sister taxon of Chelonioidea, our analysis places Protostegidae outside of the Chelonioidea crown group and recovers Allopleuron hofmanni as a stem dermochelyid. Gap excess ratio (GER) results indicate a strong stratigraphic congruence of our phylogenetic hypothesis; however, the highest GER value is associated with the phylogenetic hypothesis of marine turtles which excludes Protostegidae from the Cryptodira crown group. Ancestral range estimations derived from our phylogeny imply a European or North American origin of Chelonioidea in the middle-to-late Campanian, approximately 20 Myr earlier than current molecular divergence studies suggest.

Identifying genetic lineages through shape: An example in a cosmopolitan marine turtle species using geometric morphometrics.

The green turtle (Chelonia mydas) is a globally distributed marine species whose evolutionary history has been molded by geological events and oceanographic and climate changes. Divergence between Atlantic and Pacific clades has been associated with the uplift of the Panama Isthmus, and inside the Pacific region, a biogeographic barrier located west of Hawaii has restricted the gene flow between Central/Eastern and Western Pacific populations. We investigated the carapace shape of C. mydas from individuals of Atlantic, Eastern Pacific, and Western Pacific genetic lineages using geometric morphometrics to evaluate congruence between external morphology and species’ phylogeography. Furthermore, we assessed the variation of carapace shape according to foraging grounds. Three morphologically distinctive groups were observed which aligned with predictions based on the species’ lineages, suggesting a substantial genetic influence on carapace shape. Based on the relationship between this trait and genetic lineages, we propose the existence of at least three distinct morphotypes of C. mydas. Well-defined groups in some foraging grounds (Galapagos, Costa Rica and New Zealand) may suggest that ecological or environmental conditions in these sites could also be influencing carapace shape in C. mydas. Geometric morphometrics is a suitable tool to differentiate genetic lineages in this cosmopolitan marine species. Consequently, this study opens new possibilities to explore and test ecological and evolutionary hypotheses in species with wide morphological variation and broad geographic distribution range.

Acoustic tag retention rate varies between juvenile green and hawksbill sea turtles

BackgroundBiotelemetry has become a key tool for studying marine animals in the last decade, and a wide range of electronic tags are now available for answering a range of research questions. However, comparatively, less attention has been given to attachment methods for these tags and the implications of tag retention on study design, especially when designing a comparative study looking at multiple species. Here, we reported our findings on acoustic tag retention rates for juveniles of two species of marine turtle: the green sea turtle (Chelonia mydas) and the hawksbill sea turtle (Eretmochelys imbricata). We captured both species twice annually (spring and fall) from 2012 through 2017, as part of a capture–mark–recapture study at Buck Island Reef National Monument, St. Croix, U.S. Virgin Islands. We assessed tag retention rates using physical recaptures of turtles previously outfitted with an acoustic tag.ResultsWe deployed 72 acoustic tags on 60 juvenile greens and 37 acoustic tags on 29 hawksbills. We estimated the half-life for tags on greens to be 150 days (95% CI 117–188 days), whereas the half-life for tags on hawksbills was 1077 days (95% CI 870–2118 days), a marked difference. We observed that tag attachment holes, drilled into the posterior marginal scutes, migrated laterally towards the outer edge of the marginals in both species. Green turtles tended to exhibit tear-outs, as their attachment holes wore and/or tags grew near the edge of their scutes, whereas hawksbills tended to maintain the structure of these holes and did not exhibit these tear-outs.ConclusionsWe conclude that hawksbills can be tagged with long-battery-life acoustic tags for long-term studies of habitat use and movement patterns, whereas greens are likely to shed their tags in the 1st year, making long-term studies difficult. This study is the first clear evidence that tagging protocols should vary between species of hard-shelled turtles. Furthermore, shed tags on the seafloor continue to be detected by acoustic receivers, creating a challenge in data filtering before analysis. We encourage future research into an efficient method for filtering these data points prior to analysis.

Comparative osteology and osteometry of the coracoideum, humerus, and femur of the green turtle (Chelonia mydas) and the loggerhead turtle (Caretta caretta)

AbstractFragmented skeletal remains of marine turtles occur frequently in archaeological and natural deposits on tropical and subtropical coasts. Identifying these remains to species based on their differential osteomorphology is vital to address questions pertaining to the historical ecology, archaeology, and conservation of marine turtles globally. Although the species‐specific features of extant marine turtle skulls and carapax are relatively well known, the comparative osteomorphology and osteometry of postcranial endoskeletons in closely related species of marine turtles remains unstudied. In this paper, we provide verbal descriptions, line drawings, and photographs of diagnostic morphological criteria for the coracoideum, the humerus, and the femur of two closely related species of Cheloniidae: Chelonia mydas (green turtle) and Caretta caretta (loggerhead), based on observations on modern skeletons. We also present osteometric indices of the humerus and the femur that can be used to distinguish between both species. We comment on the applicability of these criteria on archaeological marine turtle assemblages from the Mediterranean.

Developmental differences between two marine turtle species and potential consequences for their survival at hatching

Anatomical variation is a major source for natural selection. Marine turtles are endangered and survival predictions are of important biological, ecological, social, and political value. Here, we perform a preliminary study illustrating how comparative embryology permits understanding of ontogenetic variation as a contributor for evolutionary fitness. To that end, we studied samples of Chelonia mydas and Caretta caretta embryos relative to a standardized staging system from the literature. We examined external anatomy using discrete characters in order to document interspecific variation during development of these species. We employed the ‘Standard Event System to Study Vertebrate Embryos’ to examine fitness-relevant structures. These include the limb paddles and elbows of Ch. mydas, which differentiate relatively late in ontogeny. We detected interspecific variation in the timing of trait differentiation – such as the egg tooth, closure of skull vault, carapace formation, and scale covering – and propose that these differences might be functionally and ecologically relevant for marine turtles.

Beyond trophic morphology: stable isotopes reveal ubiquitous versatility in marine turtle trophic ecology.

ABSTRACTThe idea that interspecific variation in trophic morphology among closely related species effectively permits resource partitioning has driven research on ecological radiation since Darwin first described variation in beak morphology among Geospiza.Marine turtles comprise an ecological radiation in which interspecific differences in trophic morphology have similarly been implicated as a pathway to ecopartition the marine realm, in both extant and extinct species. Because marine turtles are charismatic flagship species of conservation concern, their trophic ecology has been studied intensively using stable isotope analyses to gain insights into habitat use and diet, principally to inform conservation management. This legion of studies provides an unparalleled opportunity to examine ecological partitioning across numerous hierarchical levels that heretofore has not been applied to any other ecological radiation. Our contribution aims to provide a quantitative analysis of interspecific variation and a comprehensive review of intraspecific variation in trophic ecology across different hierarchical levels marshalling insights about realised trophic ecology derived from stable isotopes.We reviewed 113 stable isotope studies, mostly involving single species, and conducted a meta‐analysis of data from adults to elucidate differences in trophic ecology among species. Our study reveals a more intricate hierarchy of ecopartitioning by marine turtles than previously recognised based on trophic morphology and dietary analyses. We found strong statistical support for interspecific partitioning, as well as a continuum of intraspecific trophic sub‐specialisation in most species across several hierarchical levels. This ubiquity of trophic specialisation across many hierarchical levels exposes a far more complex view of trophic ecology and resource‐axis exploitation than suggested by species diversity alone. Not only do species segregate along many widely understood axes such as body size, macrohabitat, and trophic morphology but the general pattern revealed by isotopic studies is one of microhabitat segregation and variation in foraging behaviour within species, within populations, and among individuals.These findings are highly relevant to conservation management because they imply ecological non‐exchangeability, which introduces a new dimension beyond that of genetic stocks which drives current conservation planning.Perhaps the most remarkable finding from our data synthesis is that four of six marine turtle species forage across several trophic levels. This pattern is unlike that seen in other large marine predators, which forage at a single trophic level according to stable isotopes. This finding affirms suggestions that marine turtles are robust sentinels of ocean health and likely stabilise marine food webs. This insight has broader significance for studies of marine food webs and trophic ecology of large marine predators.Beyond insights concerning marine turtle ecology and conservation, our findings also have broader implications for the study of ecological radiations. Particularly, the unrecognised complexity of ecopartitioning beyond that predicted by trophic morphology suggests that this dominant approach in adaptive radiation research likely underestimates the degree of resource overlap and that interspecific disparities in trophic morphology may often over‐predict the degree of realised ecopartitioning. Hence, our findings suggest that stable isotopes can profitably be applied to study other ecological radiations and may reveal trophic variation beyond that reflected by trophic morphology.

Geography best explains global patterns of genetic diversity and postglacial co-expansion in marine turtles.

For many species, climate oscillations drove cycles of population contraction during cool glacial periods followed by expansion during interglacials. Some groups, however, show evidence of uniform and synchronous expansion, while others display differences in the timing and extent of demographic change. We compared demographic histories inferred from genetic data across marine turtle species to identify responses to postglacial warming shared across taxa and to examine drivers of past demographic change at the global scale. Using coalescent simulations and approximate Bayesian computation (ABC), we estimated demographic parameters, including the likelihood of past population expansion, from a mitochondrial data set encompassing 23 previously identified lineages from all seven marine turtle species. For lineages with a high posterior probability of expansion, we conducted a hierarchical ABC analysis to estimate the proportion of lineages expanding synchronously and the timing of synchronous expansion. We used Bayesian model averaging to identify variables associated with expansion and genetic diversity. Approximately 60% of extant marine turtle lineages showed evidence of expansion, with the rest mainly exhibiting patterns of genetic diversity most consistent with population stability. For lineages showing expansion, there was a strong signal of synchronous expansion after the Last Glacial Maximum. Expansion and genetic diversity were best explained by ocean basin and the degree of endemism for a given lineage. Geographic differences in sensitivity to climate change have implications for prioritizing conservation actions in marine turtles as well as for identifying areas of past demographic stability and potential resilience to future climate change for broadly distributed taxa.

Characterizing stable isotope relationships between green turtle (Chelonia mydas) skin and unhatched eggs.

Stable isotope analysis is used to understand the foraging habits and movements of a diverse set of organisms. Variability in stable isotope ratios among tissues derived from the same animal makes it difficult to compare data among study results in which different tissue types are evaluated. Isotopic relationships between two green turtle (Chelonia mydas) tissue types, skin and unhatched egg contents are unknown. Similarly, few data exist to evaluate the influence of time elapsed after oviposition (as a proxy for decomposition) on isotopic variability among unhatched eggs within the same nest. Skin and unhatched egg contents were collected from 69 adult female green turtles and associated nests at the Archie Carr National Wildlife Refuge in Florida, USA. Values of δ13 C, δ15 N, and δ34 S were measured for both tissue types using a continuous flow isotope ratio mass spectrometer. Standardized major-axis (SMA) regression was used to generate conversion equations of carbon, nitrogen, and sulfur isotope ratios between the two tissue types. Model selection frameworks consisting of single-factor linear models were employed per isotope ratio to assess how egg time-in-nest affected intraclutch isotopic variability. Conversion equations for all three isotope ratios indicated significant relationships between skin and unhatched egg values, although model fits were lower than found in some studies examining similar patterns in other marine turtle species. The probability of increased intraclutch variability was significantly higher among eggs collected at longer intervals after deposition. This study reports the first-ever δ13 C and δ15 N conversion equations between skin and unhatched eggs for green turtles, and the first δ34 S conversion equation for any marine turtle species. SMA regression was used to directly convert tissue values bidirectionally, unlike equations generated using ordinary least-squares regression. Issues with increased intraclutch variability at later excavation dates highlight the importance of collecting unhatched eggs as soon as possible after hatchling emergence.

First report of fibropapillomatosis in an olive ridley turtle Lepidochelys olivacea from the southeastern Pacific.

An adult olive ridley turtle Lepidochelys olivacea with lesions suggestive of fibropapillomatosis was rescued on the coast of San Antonio, central Chile. Histopathologic analysis showed an exophytic and pedunculated mass formed by epidermal papillary projections supported by fibrovascular cores, epidermal hyperplasia and marked orthokeratotic hyperkeratosis. ChHV5 unique long genes UL27, UL28 and UL30 were amplified from tumor lesions and sequenced for phylogeny. Phylogenetic reconstruction showed the Chilean sequences clustering with the Eastern Pacific group. This is the first case of fibropapillomatosis in an olive ridley turtle diagnosed in Chile and in the southeastern Pacific region. Our results suggest a regional grouping of ChHV5 variants independent of the marine turtle's species.

Inferred Adult Foraging Grounds of Two Marine Turtle Species Nesting at Amami-Oshima, Japan

Abstract During late June and July in 2015, we tracked the postnesting migrations of 5 loggerhead turtles (Caretta caretta) and 5 green turtles (Chelonia mydas) from a beach on Amami-Oshima Island ...

MarTurtSI, a global database of stable isotope analyses of marine turtles

Marine turtles are both flagship species of conservation concern and indicators of ocean health. As highly migratory species, and despite substantial research effort focusing on nesting females and satellite tagging studies, we still know little about the trophic ecology and habitat use of immature stages and males. Consequently, marine turtle biologists began using stable isotope analyses in the last decade to elucidate various aspects of trophic ecology, including habitat use and trophic position. This has resulted in a burgeoning but largely disconnected literature of mostly single-species case studies. Here we comprehensively synthesize this body of work into a unified data repository, the MarTurtSI database. MarTurtSI contains stable isotope data from six of seven marine turtle species ranging from juveniles to adults, in different developmental, feeding, and breeding habitats across multiple ocean basins. MarTurtSI will be curated and updated with the aim of enabling continued comprehensive and global investigations into the trophic ecology of marine turtles especially in the face of climate change and other conservation challenges.

Habitat Use and Behavior of Multiple Species of Marine Turtles at a Foraging Area in the Northeastern Gulf of Mexico

Multi-species conservation strategies can be useful to maximize allocation of resources. To effectively plan for multi-species management practices, it is important to have a robust understanding of the variability in the spatial and behavioral ecology of sympatric species. To address this in the context of marine turtles, this study explored fine-scale habitat use by three sympatric species (juvenile green turtles (Chelonia mydas), Kemp’s ridley turtles (Lepidochelys kempii) and loggerhead turtles (Caretta caretta)) in a foraging area near Crystal River, Florida, USA. By combining sighting surveys and satellite tracking methods, we found that the distribution of the three species of marine turtles in this region overlapped both in space and time. We also observed differences in the fine-scale location of hotspots and in-water behavior among species, with some degree of apparent habitat partitioning. Habitat partitioning was particularly evident when assessing the diving and surfacing behavior of tracked turtles, with some degree of differentiation in diel diving patterns, particularly depths utilized during daytime/nighttime and the dive/surface duration. Our study provides ecological baseline data on the spatial overlap, habitat use and behavior of three sympatric marine turtle species, which can inform future management strategies at nearshore marine habitats in the Northeastern Gulf of Mexico.

Distribution patterns of epibiotic barnacles on the Hawksbill turtle, Eretmochelys imbricata, nesting in Iran

The hawksbill turtle (Eretmochelys imbricata,) is a critically endangered species of marine turtle that occurs in the Persian Gulf. The present study analyzed the frequency and distribution of epibiont barnacles residing on 122 the carapace and plastron of nesting hawksbill turtles (mean CCL = 70.22 ± 4.3 cm; mean CCW = 64.77 ± 3.2 cm) from the northern Persian Gulf in 2017. Barnacles frequency on the carapace, plastron, flippers, and head were studied in 29 turtles of the 122 turtles. 99.2 % of the nesting hawksbill turtles hosted barnacles and 72% carried between 1 and 20 barnacles (n= 122 turtles). The plastron, carapace, flippers, and head areas of the 29 turtles hosted 2804 836, 585 and 454 barnacles, respectively. The number of barnacles smaller than 0.5 cm on carapace represented 38.8% of the total of 836 barnacles. Based on the combined totals on the plastron, flippers, and head, barnacles smaller than 0.5 cm represented 69.2% of the barnacles counted on the turtles. There was a significant difference among the barnacle frequency on different scales of carapace, plastron, and four flippers (P<0.05). The presence of numerous barnacles may influence the hydrodynamic surface and water flow around the turtle’s body. Moreover, the high density of barnacles may influence the health of the turtles. The number of barnacles residing on a hawksbill turtle may result from the foraging behavior and habitat of the turtles.

Biphasic allometric growth in juvenile green turtles Chelonia mydas

ESR Endangered Species Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials ESR 37:301-308 (2018) - DOI: https://doi.org/10.3354/esr00930 Biphasic allometric growth in juvenile green turtles Chelonia mydas Michael Salmon1,*, Cody R. Mott2, Michael J. Bresette2 1Department of Biological Sciences, Florida Atlantic University, Boca Raton, Florida, 33431, USA 2Inwater Research Group, Jensen Beach, Florida 34957, USA *Corresponding author: salmon@fau.edu ABSTRACT: Green turtles raised in the laboratory widen faster than they lengthen, thus changing in shape from the proportions they show as hatchlings. By doing so, young turtles may sooner achieve a size refuge from their gape-limited predators. In this study, we document that wild juveniles captured at open-water weed lines in the Gulf of Mexico show similarly wider proportions, demonstrating for the first time that this growth pattern occurs in nature. We additionally quantified the shell dimensions of older juveniles that had abandoned weed lines and returned to occupy shallow coastal reefs. Those turtles exhibited a narrower ’hatchling like’ body shape. We conclude that juvenile green turtles show a biphasic pattern of initial widening, followed later by a secondary narrowing once they achieve a size that exceeds 25-30 cm in straight-line carapace length. We hypothesize that secondary narrowing may be advantageous for reducing lethal interactions with a different subset of larger predators, those that typically dismember their prey rather than swallow them whole. Finally, we categorize this complex growth pattern as one of several vulnerability traits that promote juvenile turtle survival, and document that they are expressed in different combinations among other marine turtle species. KEY WORDS: Allometric growth · Evolution · Predator-prey · Sea turtle · Vulnerability traits Full text in pdf format PreviousCite this article as: Salmon M, Mott CR, Bresette MJ (2018) Biphasic allometric growth in juvenile green turtles Chelonia mydas. Endang Species Res 37:301-308. https://doi.org/10.3354/esr00930 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in ESR Vol. 37. Online publication date: December 13, 2018 Print ISSN: 1863-5407; Online ISSN: 1613-4796 Copyright © 2018 Inter-Research.