Reconstructing sea turtle ontogenetic habitat shifts through trace element analysis of bone tissue

Ramirez, Matthew D.; Miller, Jessica A.; Parks, E.; Avens, Larisa; Goshe, LR; Seminoff, JA; Snover, ML; Heppell, Scott A.

doi:10.3354/meps12796

Cited by 10 publications

(8 citation statements)

References 95 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In addition, if sulphur had been analysed for the Zakynthos nesting population then it is likely a much larger proportion of nesting females would have been assigned to a foraging region. To better delineate isotopic profiles between multiple foraging grounds and help assign more individuals to putative foraging regions, analysis of additional intrinsic markers, for example trace elements (e.g., Ramirez et al, ) or additional analytical techniques such as amino acid compound specific stable isotope analysis (e.g., Seminoff et al, ; Vander Zanden et al, ) would also be beneficial. This could be especially important in regions of complex geography and oceanography with multiple foraging regions, such as the Mediterranean Sea (Bradshaw et al, ).…”

Section: Discussionmentioning

confidence: 99%

Spatial ecology of loggerhead turtles: Insights from stable isotope markers and satellite telemetry

Haywood

Fuller

Godley

et al. 2020

Diversity and Distributions

View full text Add to dashboard Cite

Aim Using a combination of satellite telemetry and stable isotope analysis (SIA), our aim was to identify foraging grounds of loggerhead turtles (Caretta caretta) at important rookeries in the Mediterranean, examine foraging ground fidelity, and across 25 years determine the proportion of nesting females recruiting from each foraging region to a major rookery in Cyprus. Location Mediterranean Sea. Methods Between 1993 and 2018, we investigated the spatial ecology of loggerhead turtles from rookeries in Cyprus and Greece using satellite telemetry (n = 55 adults) and SIA of three elements (n = 296). Results Satellite telemetry from both rookeries revealed the main foraging areas as the Adriatic region (Cyprus: 4% of individuals, Greece: 55%), Tunisian Plateau (Cyprus: 16%, Greece: 40%) and the eastern Mediterranean (Cyprus: 80%, Greece: 5%). Combining satellite telemetry and SIA allowed 64% of all nesting females to be assigned to; the Adriatic region (Cyprus: 2%, Greece: 38.5%), Tunisian Plateau (Cyprus: 47%, Greece: 38.5%) and the eastern Mediterranean (Cyprus: 51%, Greece: 23%), which are markedly different to proportions obtained using satellite telemetry. The proportion of the Cyprus nesting cohort using each foraging region did not change significantly, with the exception that individuals foraging in the Adriatic region are only present in the Cyprus nesting population from 2012. Repeat satellite tracking (n = 3) and temporal consistency in isotope ratios (n = 36) of Cyprus females, strongly suggest foraging ground fidelity over multiple decades. Main conclusions This study demonstrates the advantages of combining satellite telemetry and SIA to investigate spatial ecology at a population level. The importance of the Tunisian Plateau for foraging is demonstrated. This study indicates that females generally show high fidelity to foraging grounds and shows a potential recent shift to foraging in the Adriatic region for Cyprus females, while the importance of other regions persists across decades, thus providing baselines to develop and assess conservation strategies.

show abstract

Section: Discussionmentioning

confidence: 99%

Spatial ecology of loggerhead turtles: Insights from stable isotope markers and satellite telemetry

Haywood

Fuller

Godley

et al. 2020

Diversity and Distributions

View full text Add to dashboard Cite

show abstract

“…US Atlantic and GoM for Kemp's ridleys and US Atlantic for loggerheads) following their oceanic-toneritic habitat transition, due to coupled shifts in nitrogen cycling at the base of occupied food webs (oceanic: N 2 -fixation, neritic: denitrification) and changes in diet (Snover 2002, Snover et al 2010, Avens et al 2013, 2020b, Goodman Hall et al 2015, Ra mirez et al 2015, 2019, Bean & Logan 2019. Although the causal mechanisms remain unclear, barium to calcium (Ba:Ca) and strontium to calcium (Sr:Ca) ratios appear to also track changes in oceanic vs. neritic resource use in these species in the GoM and along the US Atlantic (Ramirez et al 2019). Importantly, Ba:Ca and Sr:Ca ratios may provide a better tool for studying ontogenetic shifts in turtles that occupy neritic habitats in south Florida or the West Florida Shelf, where δ 15 N values may less reliably reveal oceanic-to-neritic habitat shifts.…”

Section: Characterizing Oceanic To Neritic Habitat Shiftmentioning

confidence: 99%

“…Trace element ratios were collected via laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) following Ramirez et al (2019). Briefly, bone cross-sections were polished, cleaned ultrasonically, and then mounted onto glass slides.…”

Section: Characterizing Oceanic To Neritic Habitat Shiftmentioning

confidence: 99%

Hawksbill sea turtle life-stage durations, somatic growth patterns, and age at maturation

Avens

Ramirez

Goshe

et al. 2021

Endang. Species. Res.

Self Cite

View full text Add to dashboard Cite

Sea turtles exhibit complex life histories, encompassing intermittent use of multiple spatially separated habitats throughout long lifespans. This broad scope presents challenges for collecting comprehensive biological and ecological data, yet absence of such information complicates evaluation of management strategies for populations at risk of extinction. Hawksbill sea turtles Eretmochelys imbricata are endangered worldwide, primarily due to long-term, directed harvest. However, available information regarding life stage durations, somatic growth patterns, and maturation attributes to enhance understanding of anthropogenic impacts and recovery potential remains constrained. To address these data gaps in the western North Atlantic, we conducted skeletochronological analysis for hawksbills stranded along US coastlines to generate straight-line carapace length (SCL)-at-age and somatic growth data. Generalized additive mixed models and bootstrapped von Bertalanffy growth curves were used to characterize age at maturation and covariate influence on somatic growth. For a subset of turtles, annual bone growth increment-specific stable isotope and trace element analyses were incorporated to evaluate habitat use relative to age. Integration of these data sources indicated that juveniles transitioned from oceanic to neritic habitat at 1-3 yr old and mean SCLs of 23-24 cm (range 15.7-35.0 cm). Initial ages at maturation for this population at minimum nesting female SCLs were estimated at 15-25 yr. Somatic growth varied significantly relative to size, age, and stranding location, while no association with sex or calendar year was observed. Our results demonstrate the utility of these complementary analytical approaches for generating baseline data fundamental to characterizing hawksbill sea turtle population attributes.

show abstract

“…Sea turtle diets and growth rates vary throughout their lifetime (Bjorndal, 1997;Chaloupka and Musick, 1997). To reduce the potential for ontogenetic effects to bias our results we only sampled bone growth layers from juvenile Kemp's ridleys corresponding to their benthic life stage (i.e., age ≥ 0.75 and δ 15 N values ≥ 10.7 ; Ramirez, 2019;Ramirez et al, 2019).…”

Section: Sea Turtle Stable Isotope Ratiosmentioning

confidence: 99%

“…Combining skeletochronological and stable isotope analyses within a mixing model framework may thus provide a means of investigating the influence of diet composition on sea turtle growth rates across multiple spatiotemporal scales. The integration of these tools has already shed valuable insight into sea turtle ontogenetic growth dynamics and resource shifts (Snover et al, 2010;Ramirez et al, 2017Ramirez et al, , 2019Turner Tomaszewicz et al, 2017a).…”

Section: Introductionmentioning

confidence: 99%

Regional Variation in Kemp’s Ridley Sea Turtle Diet Composition and Its Potential Relationship With Somatic Growth

et al. 2020

View full text Add to dashboard Cite

Reptile growth is influenced by many ecological processes that can cumulatively give rise to divergent somatic growth rates within spatially structured populations. As somatic growth variation can strongly influence a species' population dynamics, identifying proximate drivers can be critical to the conservation and management of protected species. Kemp's ridley sea turtles (Lepidochelys kempii) exhibit spatial variation in both diet composition and growth, but whether components of this variation are linked has not been evaluated. Through an integration of skeletochronological and stable isotope analyses of stranded turtle humerus bones we characterized regional variation in Kemp's ridley diet composition and potential relationships with somatic growth rates. Turtles were divided among five regions within the United States Gulf of Mexico (GoM) and Atlantic Coast based on location of stranding, and humerus bones were sampled for stable carbon (δ 13 C) and nitrogen (δ 15 N) isotope ratios. These data were combined with region-specific prey stable isotope data sourced from the primary literature into Bayesian stable isotope mixing models (MixSIAR) to estimate the proportional contribution of five prey groups (crustaceans, bivalves, gastropods, fish, and macroalgae/seagrass) to Kemp's ridley diets. Our analysis revealed strong regional differences in mixing model-derived diet composition estimates that closely tracked published records of Kemp's ridley diet. Invertebrates generally comprised the largest proportion (43.5-97.7%) of turtle diets. However, we also observed high proportional contributions of fish (42.6-43.1%) to western GoM turtle diets and macroalgae/seagrass (42.4-47.8%), or isotopically similar prey resources (e.g., tunicates), to eastern GoM turtle diets. Growth rates were poorly correlated with δ 15 N values-a proxy for trophic level-and diet composition estimates, suggesting that diet composition alone may not explain the regional differences in somatic growth observed in this species. This study highlights the value of complementary skeletal and isotopic analyses to understanding regional

show abstract

Reconstructing sea turtle ontogenetic habitat shifts through trace element analysis of bone tissue

Cited by 10 publications

References 95 publications

Spatial ecology of loggerhead turtles: Insights from stable isotope markers and satellite telemetry

Spatial ecology of loggerhead turtles: Insights from stable isotope markers and satellite telemetry

Hawksbill sea turtle life-stage durations, somatic growth patterns, and age at maturation

Regional Variation in Kemp’s Ridley Sea Turtle Diet Composition and Its Potential Relationship With Somatic Growth

Contact Info

Product

Resources

About