Site fidelity, ontogenetic shift and diet composition of green turtles Chelonia mydas in Japan inferred from stable isotope analysis

Shimada, Takahiro; Aoki, Shigeru; Kameda, Kazunari; Hazel, Julia; Reich, Kimberly J.; Kamezaki, Naoki

doi:10.3354/esr00616

Cited by 64 publications

(51 citation statements)

References 48 publications

(48 reference statements)

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“…This could lead to more assured individual-level assignments regarding natal origins, in contrast to the few individuals that may currently be assigned through low-frequency endemic haplotypes. Additional methods of characterising individuals to a geographical area, such as use of biochemical markers like stable isotopes (Zbinden et al 2011; Ceriani et al 2012; Shimada et al 2014), even in the absence of external markers, could enhance our understanding of a specific foraging area’s region-wide links to nesting sites through complementary sampling of individuals observed nesting.…”

Section: Discussionmentioning

confidence: 99%

Linking loggerhead locations: using multiple methods to determine the origin of sea turtles in feeding grounds

et al. 2017

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Many marine megavertebrate taxa, including sea turtles, disperse widely from their hatching or birthing locations but display natal homing as adults. We used flipper tagging, satellite tracking and genetics to identify the origin of loggerhead turtles living in Amvrakikos Gulf, Greece. This location has been identified as hosting regionally important numbers of large-juvenile to adult sized turtles that display long-term residency and/or association to the area, and also presents a male biased sex ratio for adults. A total of 20 individuals were linked to nesting areas in Greece through flipper tagging and satellite telemetry, with the majority (16) associated with Zakynthos Island. One additional female was tracked from Amvrakikos Gulf to Turkey where she likely nested. Mitochondrial DNA mixed stock analyses of turtles captured in Amvrakikos Gulf (n = 95) indicated 82% of individuals originated from Greek nesting stocks, mainly from Zakynthos Island (63%), with lesser contributions from central Turkey, Cyprus and Libya. These results suggest that the male-biased sex ratio found in Amvrakikos Gulf may be driven by the fact that males breed twice as frequently on Zakynthos, resulting in their using foraging grounds of greater proximity to the breeding site. Conservation measures in localised foraging habitats for the protection of marine vertebrates, such as sea turtles, may have positive impacts on several disparate breeding stocks and the use of multiple methods to determine source populations can indicate the relative effectiveness of these measures.Electronic supplementary materialThe online version of this article (doi:10.1007/s00227-016-3055-z) contains supplementary material, which is available to authorized users.

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Section: Discussionmentioning

confidence: 99%

Linking loggerhead locations: using multiple methods to determine the origin of sea turtles in feeding grounds

et al. 2017

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“…While our study has provided valuable data regarding the movements of juvenile hawksbill turtles around an offshore developmental habitat, other methods of long-term monitoring, such as satellite telemetry and stable isotope analysis, would permit insights even if tracked individuals were to leave the atoll (Shimada et al 2014). Technological advances aside, with suffi-cient commitment of time and resources, there is also much still to be gained from traditional capturemark-recapture methods (Patrício et al 2014).…”

Section: Future Directionsmentioning

confidence: 99%

Movement patterns of juvenile hawksbill turtles Eretmochelys imbricata at a Caribbean coral atoll: long-term tracking using passive acoustic telemetry

Chevis¹,

Godley²,

Lewis³

et al. 2017

Endang. Species. Res.

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Understanding the ecological interactions that underlie marine ecosystem functioning requires sufficient data describing habitat use by mobile species. Hawksbill turtles Eretmochelys imbricata are considered a key species in coral reef-associated communities, owing to their specific foraging preferences, yet new information is still revealing details of the spatial and temporal aspects of habitat use. We used passive acoustic telemetry to monitor the movements of 18 juvenile hawksbills (minimum curved carapace length: 32.0−59.7 cm, mean ± SD = 43.9 ± 6.7 cm) at a developmental foraging site in a Mesoamerican barrier reef, Lighthouse Reef Atoll in Belize (tracking duration 10−1414 d, mean ± SD = 570 ± 484 d). Although specific home ranges were difficult to quantify, several turtles showed high site fidelity over timescales of months to years, with occasional wide-ranging use of the atoll. Diel variation in the number of detections received strongly suggest nocturnal resting. Long-term tracking data reveal 3 degrees of site fidelity across the atoll, based on the number of detection days near individual stations: high residency (n = 4 turtles), sequential residency (n = 5), and transient behavior (n = 4). These variations in movement raise questions about the differentiation of foraging habitats and degree of individual specialization within this population, as well as the influences of microhabitats and human disturbance.

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“…This study builds upon a growing body of evidence that green turtles (Broderick et al 2007, Vander Zanden et al 2013, Shimada et al 2014 and other marine turtle species (Schofield et al 2010, Thomson et al 2012, Tucker et al 2014, Pajuelo et al 2016 show high levels of fidelity to non-breeding sites. The ability to isotopically track some individuals for up to 4 breeding seasons, with a temporal frame of ap proxi mately 2 to 8 yr, presented clear evidence for a high degree of fidelity to the pre-defined foraging areas.…”

Section: Ascertaining Foraging Site Fidelitymentioning

confidence: 99%

Satellite tracking and stable isotope analysis highlight differential recruitment among foraging areas in green turtles

Bradshaw¹,

Broderick²,

Carreras³

et al. 2017

Mar. Ecol. Prog. Ser.

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Identifying links between breeding and non-breeding sites in migratory animals is an important step in understanding their ecology. Recognising the relative importance of foraging areas and ascertaining site-specific levels of recruitment can provide fundamental and applied insights. Here, satellite telemetry and the stable isotope ratios (δ 13 C, δ 15 N and δ 34 S) of 230 green turtles Chelonia mydas from a regionally important rookery in northern Cyprus were employed to evaluate the relative importance of 4 foraging areas. A preliminary analysis of stable isotope ratios suggested that a major foraging area had been missed through satellite telemetry as a large proportion of turtles had isotope ratios that did not correspond to sites previously identified. Stable isotope ratios were then employed to select 5 turtles to be fitted with platform terminal transmitters in 2015. All 5 turtles were subsequently tracked to the same location, Lake Bardawil in Egypt. Serially collected tissue samples from 45 females, ranging over 2 to 4 breeding seasons, suggested that foraging site fidelity was very common, with 82% of females exhibiting extremely high temporal consistency in isotope ratios. Quantifying fidelity allowed an evaluation of foraging areaspecific contributions to each breeding cohort over the past 2 decades and demonstrated that recruitment was unequal among sites, and dynamic over time, with Egypt now currently the major contributor to the nesting aggregation. This work demonstrates the utility of stable isotope analysis to elucidate the spatial ecology of cryptic taxa and illustrates how more robust baselines can be assembled against which to measure the success of future marine conservation initiatives.

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Site fidelity, ontogenetic shift and diet composition of green turtles Chelonia mydas in Japan inferred from stable isotope analysis

Abstract: Incomplete knowledge about local foraging ecology of green turtles hampers their conservation management in Japan, where stocks have only partially recovered from heavy exploitation in previous centuries. We used stable isotope ratios of δ 13 C and δ 15

Cited by 64 publications

References 48 publications

Linking loggerhead locations: using multiple methods to determine the origin of sea turtles in feeding grounds

Linking loggerhead locations: using multiple methods to determine the origin of sea turtles in feeding grounds

Movement patterns of juvenile hawksbill turtles Eretmochelys imbricata at a Caribbean coral atoll: long-term tracking using passive acoustic telemetry

Satellite tracking and stable isotope analysis highlight differential recruitment among foraging areas in green turtles

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