Dataset Submitted

Sequential bomb radiocarbon data for scute growth rate estimation in green (Chelonia mydas) and loggerhead (Caretta caretta) sea turtles

Authors: Amy Wallace, Alexandra Fireman, Jenna Bennett
Identified On: May 29 2025 18:41 UTC
DOI: https://doi.org/10.7266/wf62nacr
UDI: F3.x304.000:0004
Project Information

Funded By:
Florida RESTORE Act Centers of Excellence Program

Funding Cycle:
FLRACEP 3

Research Group:
Tissue Clocks: New Methods for Ageing and Decoding Sea Turtle Life Histories

Point of Contact

Bethan Linscott
University of Florida
bethan.linscott@outlook.com

Data Collection Period
2020-01-01
to
2022-09-01
Theme keywords

sea turtle, scute, radiocarbon, incremental

Abstract:

Incrementally formed biological tissues can provide an archive of biochemical information pertaining to the life histories of organisms. In order to estimate the time periods represented by such data, the growth rates of incremental tissues must be known. In order to establish the growth rates of green turtle (Chelonia mydas) and loggerhead turtle (Caretta caretta) scute keratin, we obtained 154 bomb radiocarbon measurements from the sequentially sampled scute biopsies of 32 individuals who stranded along the coasts of Florida between 2019-2022. Using a Bayesian depositional modelling approach and a local radiocarbon reference series compiled using measurements from known-age corals and otoliths, we reconstructed scute growth rates for each individual. This dataset provides the unmodelled, sequential radiocarbon data for each individual and accompanying details regarding stranding location, date and carapace length.

Suggested Citation:

Amy Wallace, Alexandra Fireman, Jenna Bennett. Sequential bomb radiocarbon data for scute growth rate estimation in green (Chelonia mydas) and loggerhead (Caretta caretta) sea turtles. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/wf62nacr

Purpose:

These data were gathered in order to model the growth rates of loggerhead (Caretta caretta) and green (Chelonia mydas) turtles in the Gulf of Mexico and SW Atlantic.

Data Parameters and Units:

Turtle_ID: A unique identifier for each individual Species: Species of each individual Stranding_county: County in which the individual stranded Latitude: Stranding latitude Longitude: Stranding longitude Stranding_date: Date (year-month-day) upon which the individual stranded SCL: Straight carapace length (cm) Depth: Depth of scute layer from the outermost surface (µm) Mass: Mass of the scute sample (mg) F14C: Measured fraction modern data for the scute sample F14C_err: Fraction modern standard deviation for the scute sample D14C: Radiocarbon values for the scute sample (permil)

Methods:

All turtle scute collections and tissue dissections were carried out under Marine Turtle Permits MTP-20-016, MTP-21-016, and MTP-22-016 granted by Florida Fish and Wildlife Conservation Commission, and the University of Florida Institutional Animal Care and Use Committee (IACUC) protocol number 202001985. Scute samples were obtained from 15 stranded and deceased loggerhead turtles and 17 stranded and deceased green turtles with varying straight carapace lengths (SCL) from a combination of Sea Turtle Stranding and Salvage Network (STSSN) necropsy sessions and from rehabilitation facilities where patients died on site. For green and loggerhead turtles, the central region of the second and third lateral scutes were selected for sampling respectively. All metal tools and aluminium foil used to sample, store, and prepare samples were baked in a muffle furnace at 450°C for four hours prior to use to ensure all organics were removed. Glassware was acid-washed and baked in a muffle furnace at 450°C prior to use. During necropsy sessions, scutes were removed from carapaces using stainless-steel knives and stored in baked aluminum foil within Ziplock bags at -20°C. Prior to processing, the scutes were removed from the freezer and cleaned of surface debris such as dirt and algal growth using a baked stainless-steel scoopula and ultra-pure water (18.2 ΜΩ cm-1). A 6-mm diameter keratin biopsy was removed from the central region of each scute using a reusable stainless steel biopsy punch, which was baked at 450°C between each sample. Each scute biopsy was then soaked in ultra-pure water for at least 12 hours to remove any remaining dirt and debris, and subsequently dried for 24 hours in a drying oven at 60°C. Each keratin biopsy sample was affixed dorsal-side up to a microscope slide using Crystal Bond™ adhesive resin. Layers of keratin were removed in 50 µm increments at between 55 and 75 RPM using a Sherline 5100A-DRO benchtop mill equipped with a 1/16th drill bit baked at 450°C, and the resulting powder was inspected under a dissecting microscope for residual resin. Milling was terminated once a removed layer contained multiple resin fragments, and this layer was excluded from analysis. Consequently, the most recent layer of scute was not sampled for any turtle. All samples were sent to the National Ocean Sciences Accelerator Mass Spectrometry facility (NOSAMS) for 14C analysis using a MICADAS system (Ionplus AG, Switzerland). Reported precision is 3-4‰.