Somatic growth rates of immature green turtles Chelonia mydas inhabiting the foraging ground Akumal Bay in the Mexican Caribbean Sea

Labrada-Martagón, Vanessa; Tenería, Fernando Alberto Muñoz; Herrera-Pavón, Roberto L.; Negrete-Philippe, Ana

doi:10.1016/j.jembe.2016.11.015

Cited by 16 publications

(7 citation statements)

References 54 publications

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“…The monitors working for more than 20 years in the area who marked the marine turtles recorded successful nesting by the same turtles on Akumal beaches approximately 18 years later. This view is also corroborated by Labrada-Martagón et al 6 .…”

Section: Discussionsupporting

confidence: 79%

“…The Quintana Roo beaches of the Yucatán Peninsula belong to the Western Caribbean Marine Ecoregion (the scale unit in the Marine Ecoregions of the World system) in the tropical northwestern Atlantic [1][2][3] . The beaches in this ecoregion served as nesting 4 and foraging grounds 5,6 for marine turtles long before humans settled on the American continent 7 . Human pressures have impeded sea turtle habitats in many ways.…”

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confidence: 99%

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Caretta caretta nesting activity on Akumal Beaches, Mexico

González

Anastácio²,

Lizárraga-Cubedo

et al. 2020

Sci Rep

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Mexico has made substantial contributions to marine turtle protection and conservation, especially since 1990. Several conservation projects entail monitoring efforts to recover nesting territories for marine turtles. The Sea Turtle Protection Program of Akumal, in the Mexican state of Quintana Roo, was created in 1993 and was developed by the Akumal Ecological Center. This paper provides the nesting ecology parameters for Caretta caretta over a protection period of 24 years (1995-2018). A well-defined nesting peak was observed in June, with a nesting success rate of 75.2 ± 23.0%. Nesting females showed a mean curved carapace length of 99.0 ± 5.6 cm. The mean clutch size was 108.6 ± 24.6 eggs, with variation among years. The mean incubation period was 57.2 ± 6.2 days. The hatching and emergence success rates were 87.2 ± 16.9% and 78.8 ± 24.4%, respectively. For the 926 tagged females that returned, the remigration interval peaked at 726 days, with a 12-day inter-nesting period. The results show not only the recovery of the nesting population over time but also a decrease in female size; we postulate that this decrease is due to the recruitment of young females, which has been increasingly pronounced since 2010. Hence, the Akumal rookery plays an important role in its corresponding regional management unit (Atlantic Northwest).

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Section: Discussionsupporting

confidence: 79%

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confidence: 99%

Caretta caretta nesting activity on Akumal Beaches, Mexico

González

Anastácio²,

Lizárraga-Cubedo

et al. 2020

Sci Rep

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“…Also, as stated above, quality and quantity of foraging areas for sea turtles are declining; thus, lowering the population levels of green turtles at which density‐dependent effects would be invoked. Evidence for density‐dependent regulation of growth rates was reported for three green turtle study sites (The Bahamas, Florida, USA, and México; Bjorndal, Bolten, & Chaloupka, ; Kubis, Chaloupka, Ehrhart, & Bresette, ; Labrada‐Martagón, Muñoz Tenería, Herrera‐Pavón, & Negrete‐Philippe, ), but no evidence of a density‐dependent effect was found in a green turtle aggregation in Puerto Rico (Patrício, Diez, & van Dam, ). Density dependence cannot be the major driver because the three species of sea turtles would not simultaneously reach the population levels at which density dependence would begin to regulate somatic growth on a region‐wide basis.…”

Section: Discussionmentioning

confidence: 98%

Ecological regime shift drives declining growth rates of sea turtles throughout the West Atlantic

Bjorndal

Bolten

Chaloupka³

et al. 2017

Global Change Biology

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Somatic growth is an integrated, individual-based response to environmental conditions, especially in ectotherms. Growth dynamics of large, mobile animals are particularly useful as bio-indicators of environmental change at regional scales. We assembled growth rate data from throughout the West Atlantic for green turtles, Chelonia mydas, which are long-lived, highly migratory, primarily herbivorous mega-consumers that may migrate over hundreds to thousands of kilometers. Our dataset, the largest ever compiled for sea turtles, has 9690 growth increments from 30 sites from Bermuda to Uruguay from 1973 to 2015. Using generalized additive mixed models, we evaluated covariates that could affect growth rates; body size, diet, and year have significant effects on growth. Growth increases in early years until 1999, then declines by 26% to 2015. The temporal (year) effect is of particular interest because two carnivorous species of sea turtles-hawksbills, Eretmochelys imbricata, and loggerheads, Caretta caretta-exhibited similar significant declines in growth rates starting in 1997 in the West Atlantic, based on previous studies. These synchronous declines in productivity among three sea turtle species across a trophic spectrum provide strong evidence that an ecological regime shift (ERS) in the Atlantic is driving growth dynamics. The ERS resulted from a synergy of the 1997/1998 El Niño Southern Oscillation (ENSO)-the strongest on record-combined with an unprecedented warming rate over the last two to three decades. Further support is provided by the strong correlations between annualized mean growth rates of green turtles and both sea surface temperatures (SST) in the West Atlantic for years of declining growth rates (r = -.94) and the Multivariate ENSO Index (MEI) for all years (r = .74). Granger-causality analysis also supports the latter finding. We discuss multiple stressors that could reinforce and prolong the effect of the ERS. This study demonstrates the importance of region-wide collaborations.

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“…Cause 2 (differences in growth rate) does not seem to provide an obvious explanation, either. Studies in the region have found slightly greater growth rates for juvenile greens than for hawksbills [29,30]; however, variability in somatic growth rates can be due to a number of different factors including cohort, population density, and quality of habitat. We calculated the annual change in straight carapace length to the notch (SCL-n) for recaptured individuals to be 3.3 cm (SD = 1.2 cm) for greens and 3.5 cm (SD = 1.6 cm) for hawksbills (THS, unpublished data).…”

Section: Discussionmentioning

confidence: 94%

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

et al. 2019

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Background: Biotelemetry 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. Results:We 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. Conclusions:We 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 hardshelled 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.

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Somatic growth rates of immature green turtles Chelonia mydas inhabiting the foraging ground Akumal Bay in the Mexican Caribbean Sea

Cited by 16 publications

References 54 publications

Caretta caretta nesting activity on Akumal Beaches, Mexico

Caretta caretta nesting activity on Akumal Beaches, Mexico

Ecological regime shift drives declining growth rates of sea turtles throughout the West Atlantic

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

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