Isotopic ecology of Hawaiian green sea turtles (Chelonia mydas) and reliability of δ13C, δ15N, and δ34S analyses of unprocessed bone samples for dietary studies

Velasquez-Vacca, Adriana; Seminoff, Jeffrey A.; Jones, T. Todd; Balazs, George H.; Cardona, Luis

doi:10.1007/s00227-023-04232-1

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Isotopic ecology of Hawaiian green sea turtles (Chelonia mydas) and reliability of δ13C, δ15N, and δ34S analyses of unprocessed bone samples for dietary studies

2023
By Velasquez-Vacca, Adriana ; Seminoff, Jeffrey A. ; Jones, T. Todd ; ...

Details

Journal Title:

Marine Biology
Personal Author:

Velasquez-Vacca, Adriana ; Seminoff, Jeffrey A. ; Jones, T. Todd ; Balazs, George H. ; Cardona, Luis
NOAA Program & Office:

NMFS (National Marine Fisheries Service) ; SWFSC (Southwest Fisheries Science Center) ; PIFSC (Pacific Islands Fisheries Science Center)
Description:

This study conducted stable isotope analysis (δ13C, δ15N, and δ34S) on the epidermis and two skeletal elements (rib and squamosal bones) of Hawaiian green turtles (Chelonia mydas) and putative diet items obtained from two neritic sites: the Kona/Kohala coast and Oahu. Turtle tissues were collected in 2018–2020 and diet samples in 2018, 2019, and 2021. The effect of body size and sampling locality on individual bulk tissue isotope values was evaluated, and stable isotope mixing models based on δ13C, δ15N, and δ34S values from those tissues and four groups of food sources were used to reconstruct diet histories of the turtles. Mixing models indicated that green turtles along the Kona/Kohala coast consumed an omnivorous diet, whereas those from Oahu had an herbivorous diet. These diet make-ups are consistent with published gut content analyses. However, mixing models using the stable isotope ratios in rib and squamosal bone failed to yield reasonable diet histories, probably due to inadequacies of the applied trophic discrimination factor (TDF), a key model parameter. These results further establish that stable isotope ratios in the epidermis can be used effectively to study green turtle diet, but also reveal that more validation—and establishment of appropriate TDFs—is needed before bone can be used reliably to assess green turtle diet.
Keywords:

Aquatic Science Ecology Ecology, Evolution, Behavior And Systematics Ecology, Evolution, Behavior And Systematics Ecology, Evolution, Behavior And Systematics
Source:

Marine Biology, 170(7)
DOI:

https://doi.org/10.1007/s00227-023-04232-1
ISSN:

0025-3162 ; 1432-1793
Format:

PDF
Publisher:

Springer Science and Business Media LLC
Document Type:

Journal Article
License:

https://creativecommons.org/licenses/by/4.0
Rights Information:

CC BY
Compliance:

Submitted
Main Document Checksum:

urn:sha256:9efe30360fca78a727dcee4a516bb409622f8dd38912dc0f18bb6e3e4361400d
Download URL:

https://repository.library.noaa.gov/view/noaa/50639/noaa_50639_DS1.pdf
File Type:

[PDF - 1.86 MB ]

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