Comparison of plasma androgen profiles in green and hawksbill sea turtles inhabiting Queensland waters

2004 ◽  
Vol 52 (3) ◽  
pp. 293 ◽  
Author(s):  
Tim S. Jessop ◽  
Colin J. Limpus ◽  
Joan M. Whittier
Keyword(s):  
Seasonal Variation ◽  
Phase Shift ◽  
Chelonia Mydas ◽  
Wild Populations ◽  
Ontogenetic Changes ◽  
Eretmochelys Imbricata ◽  
Green Turtles ◽  
Hawksbill Turtles ◽  
Delayed Phase ◽  
Androgen Levels

Investigations were made into profiles of plasma androgens (combined testosterone and 5α-dihydrotestosterone) in green (Chelonia mydas) and hawksbill (Eretmochelys imbricata) turtles inhabiting waters off Queensland, Australia. First, we documented the occurrence of sex-based and ontogenetic changes in plasma androgen of immature green and hawksbill turtles occurring in wild populations. Specifically, androgen levels are increased in pubescent individuals and adults of both species and sexes. Second, we measured seasonal variation in plasma androgen profiles of adult male green and hawksbill turtles. Third, we compared plasma androgens of post-nesting green and hawksbill turtles. As for previous studies on captive green turtles, our data indicate that wild populations of green turtles also show a prenuptial spermatogenic pattern, in which plasma androgen levels rise and peak prior to migration and courtship. However, our data from male hawksbill turtles are in contrast to this pattern and provide some evidence to suggest that a delayed phase shift may occur in this population. Unlike male green turtles, male hawksbill turtles in this study all showed signs of physiological preparation for breeding.

Intake and excretion of arsenicals in green (Chelonia mydas) and hawksbill turtles (Eretmochelys imbricata)

2011 ◽  
Vol 8 (1) ◽  
pp. 19 ◽  
Author(s):  
Tetsuro Agusa ◽  
Kozue Takagi ◽  
Todd W. Miller ◽  
Reiji Kubota ◽  
Yasumi Anan ◽  
...  
Keyword(s):  
Feeding Behaviour ◽  
Chelonia Mydas ◽  
Water Soluble ◽  
Marine Animals ◽  
Eretmochelys Imbricata ◽  
Accumulation Pattern ◽  
Turtle Species ◽  
Green Turtles ◽  
Hawksbill Turtles ◽  
Prey Items

Environmental context Although among higher marine animals, relatively high concentration of arsenic and unique distribution of arsenic compounds are found in green (Chelonia mydas) and hawksbill turtles (Eretmochelys imbricata), the accumulation mechanism remains unknown. We examined the accumulation of arsenicals in two turtles from the standpoint of short- and long-term intake and excretion and found that prey items might be important for the arsenic accumulation. This study can provide useful information on the accumulation pattern of arsenic speciation in sea turtles. Abstract We analysed arsenic (As) compounds in the stomach and intestine contents, bile and urine of green (Chelonia mydas) and hawksbill turtles (Eretmochelys imbricata) to understand As accumulation through intake and excretion. Stable isotopes of δ15N and δ13C were also measured for understanding the feeding behaviour dependent accumulation of As. Major As species in gastrointestinal contents were unknown water-soluble As, followed by unextracted As. Concentrations of AB and DMA in the tissues were higher than those in the stomach contents (prey items), indicating high bioaccumulation of these arsenicals. In green turtles, AB concentration was high in bile and increased throughout the gastrointestinal tract, suggesting significant biliary excretion of AB. δ15N was positively correlated with AB level in green turtles, whereas a negative relationship between residual As and δ15N was observed in hawksbill turtles. This study indicates feeding behaviour-dependent accumulation of As compounds in both turtle species for the first time.

Green Sea Turtles Stranded by Cyclone Kathy on the South-Westeern Coast of the Culf of Carpentaria

1985 ◽  
Vol 12 (3) ◽  
pp. 523 ◽  
Author(s):  
CJ Limpus ◽  
PC Reed
Keyword(s):  
Breeding Season ◽  
Chelonia Mydas ◽  
Olive Ridley ◽  
Eretmochelys Imbricata ◽  
Lepidochelys Olivacea ◽  
Green Sea Turtles ◽  
Green Turtles ◽  
Previous Season ◽  
Hawksbill Turtles ◽  
Principal Species

Cyclone Kathy on 23 March 1984 stranded many green turtles, Chelonia mydas, on the coast adjacent to the Sir Edward Pellew Is. It is estimated that over 1000 were thrown up by the storm surge and that over 500 were left stranded by the receding waters, including migrants from the Raine I. rookery. These turtles, which were predominately large females, had been feeding close inshore on seagrass. Of the mature females sampled, 62% were preparing to breed in the next breeding season but none had bred in the previous season. The flatback turtle, Chelonia depressa, the principal species breeding on the Sir Edward Pellew Is, was not involved in the stranding. Hawksbill turtles, Eretmochelys imbricata, and olive ridley turtles, Lepidochelys olivacea, which occur in the deeper offshore waters were also not stranded. Some of the rescued turtles were subsequently recaptured nesting at Raine I.

scholarly journals An assessment of the marine turtle fishery in Grenada, West Indies

Oryx ◽  
2007 ◽  
Vol 41 (3) ◽  
pp. 330-336 ◽  
Author(s):  
S. Grazette ◽  
J.A. Horrocks ◽  
Paul E. Phillip ◽  
Crafton J. Isaac
Keyword(s):  
Breeding Season ◽  
Landing Site ◽  
Chelonia Mydas ◽  
Marine Turtle ◽  
Catch Per Unit Effort ◽  
Eretmochelys Imbricata ◽  
Green Turtles ◽  
Hawksbill Turtles ◽  
Relative Scarcity ◽  
Made In

AbstractThe marine turtle fishery of Grenada was assessed using interviews with marine turtle fishermen and by examination of turtle catch data from a major landing site. An estimated 782 turtles, mainly Endangered green turtles Chelonia mydas and Critically Endangered hawksbill turtles Eretmochelys imbricata, were caught around Grenada and its sister island Carriacou each year between 1996 and 2001 during an annual 8-month open season, with only a small percentage being officially recorded at a landing site. Turtles were primarily caught with nets and spearguns, with more green turtles caught by net fishermen and more hawksbill turtles by spear fishermen. Catch per unit effort data suggested that relative abundance had declined since the previous estimate was made in 1969. Few adult green or loggerhead turtles Caretta caretta were caught, indicating the relative scarcity of this size class of these two species around Grenada. Adult-sized hawksbill turtles were caught regularly, with larger adults being caught in the non-breeding months of the open season than in the breeding months. A higher percentage of adult hawksbill turtles present during the breeding season are likely to be animals that nest in Grenada, and their smaller size may result from historically heavy fishing pressure. The larger sized adults caught during the non-breeding season are likely to be animals that forage around Grenada but breed elsewhere in the Caribbean where they are protected.

scholarly journals Evidence for Host Selectivity and Specialization by Epizoic Chelonibia Barnacles Between Hawksbill and Green Sea Turtles

2021 ◽  
Vol 9 ◽  
Author(s):  
Liberty L. Boyd ◽  
John D. Zardus ◽  
Courtney M. Knauer ◽  
Lawrence D. Wood
Keyword(s):  
Sea Turtles ◽  
Shell Growth ◽  
Chelonia Mydas ◽  
Eretmochelys Imbricata ◽  
Turtle Species ◽  
Green Sea Turtles ◽  
Green Turtles ◽  
Microbial Biofilms ◽  
Host Relationships ◽  
Hawksbill Turtles

Epibionts are organisms that utilize the exterior of other organisms as a living substratum. Many affiliate opportunistically with hosts of different species, but others specialize on particular hosts as obligate associates. We investigated a case of apparent host specificity between two barnacles that are epizoites of sea turtles and illuminate some ecological considerations that may shape their host relationships. The barnacles Chelonibia testudinaria and Chelonibia caretta, though roughly similar in appearance, are separable by distinctions in morphology, genotype, and lifestyle. However, though each is known to colonize both green (Chelonia mydas) and hawksbill (Eretmochelys imbricata) sea turtles, C. testudinaria is >5 times more common on greens, while C. caretta is >300 times more common on hawksbills. Two competing explanations for this asymmetry in barnacle incidence are either that the species’ larvae are spatially segregated in mutually exclusive host-encounter zones or their distributions overlap and the larvae behaviorally select their hosts from a common pool. We indirectly tested the latter by documenting the occurrence of adults of both barnacle species in two locations (SE Florida and Nose Be, Madagascar) where both turtle species co-mingle. For green and hawksbill turtles in both locations (Florida: n = 32 and n = 275, respectively; Madagascar: n = 32 and n = 125, respectively), we found that C. testudinaria occurred on green turtles only (percent occurrence – FL: 38.1%; MD: 6.3%), whereas the barnacle C. caretta was exclusively found on hawksbill turtles (FL: 82.2%; MD: 27.5%). These results support the hypothesis that the larvae of these barnacles differentially select host species from a shared supply. Physio-biochemical differences in host shell material, conspecific chemical cues, external microbial biofilms, and other surface signals may be salient factors in larval selectivity. Alternatively, barnacle presence may vary by host micro-environment. Dissimilarities in scute structure and shell growth between hawksbill and green turtles may promote critical differences in attachment modes observed between these barnacles. In understanding the co-evolution of barnacles and hosts it is key to consider the ecologies of both hosts and epibionts in interpreting associations of chance, choice, and dependence. Further studies are necessary to investigate the population status and settlement spectrum of barnacles inhabiting sea turtles.

scholarly journals Ascension Island as a mid-Atlantic developmental habitat for juvenile hawksbill turtles

2014 ◽  
Vol 97 (4) ◽  
pp. 813-820 ◽  
Author(s):  
Sam B. Weber ◽  
Nicola Weber ◽  
Brendan J. Godley ◽  
Tara Pelembe ◽  
Stedson Stroud ◽  
...  
Keyword(s):  
Benthic Algae ◽  
Chelonia Mydas ◽  
Small Population ◽  
Future Research ◽  
Home Ranges ◽  
Utilization Distribution ◽  
Eretmochelys Imbricata ◽  
Ascension Island ◽  
Minimum Residence Time ◽  
Hawksbill Turtles

Ascension Island in the South Atlantic Ocean is renowned for its globally-important nesting population of green turtles (Chelonia mydas) that has been the subject of long-term research. By comparison, very little is known about the apparently small population of hawksbill turtles (Eretmochelys imbricata) that have been recorded in its waters, thousands of kilometres from known nesting beaches. Here, we collate 10 years of in-water tagging data, opportunistic public sighting records and underwater observations to provide a baseline for future research, and present preliminary data on habitat use derived from two individuals fitted with GPS transmitters. Although public sightings were inevitably biased towards popular recreation areas, the resulting distribution suggests that hawksbill turtles occur year round in Ascension Island's waters along the entire 65 km of coastline. Hawksbills were observed feeding on benthic algae and encrusting sponges, and were frequently seen scavenging on fish discards around the Island's pier at night aided by anthropogenic lighting. Between 2003 and 2013, 35 turtles were captured, measured, tagged and then released. Curved carapace lengths ranged from 33.5 to 85 cm (mean = 48.8 cm) indicating that most (if not all) individuals encountered around Ascension are post-pelagic juveniles. Four individuals were recaptured at least once giving a mean minimum residence time of 4.2 yr (range: 2.8–7.3 yr) and a mean growth rate of 2.8 cm yr−1. Turtles fitted with Fastloc™ GPS devices remained at Ascension Island for the duration of the study (>90 days) and occupied restricted home ranges with an average area of 2.5 km2 and an average ‘core use area’ (50% utilization distribution) of 0.05 km2. Together, these results suggest that Ascension Island serves as a mid-Atlantic developmental habitat for benthic-feeding, juvenile hawksbill turtles on extended oceanic migrations before recruiting to their adult foraging grounds, likely to be located in Brazil or tropical West Africa.

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