10.5061/DRYAD.XGXD254KT
Ramirez, Matthew
0000-0002-9628-8517
University of Rhode Island
Avens, Larisa
National Marine Fisheries Service
Meylan, Anne
Florida Fish and Wildlife Conservation Commission
Shaver, Donna
Korea National Park Service
Stahl, Angela
University of Rhode Island
Meylan, Peter
Eckerd College
Clark, Jamie
National Marine Fisheries Service
Howell, Lyndsey
National Marine Fisheries Service
Stacy, Brian
National Oceanic and Atmospheric Administration
Teas, Wendy
National Marine Fisheries Service
McMahon, Kelton
University of Rhode Island
Dietary plasticity linked to divergent growth trajectories in a critically
endangered sea turtle
Dryad
dataset
2022
FOS: Biological sciences
amino acid
CSIA-AA
compound-specific isotope analysis
Eretmochelys imbricata
trophic position
somatic growth
Sponges
National Science Foundation
https://ror.org/021nxhr62
1907144
2022-12-27T00:00:00Z
2022-12-27T00:00:00Z
en
83418 bytes
4
CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
Foraging habitat selection and diet quality are key factors that influence
individual fitness and metapopulation dynamics through effects on
demographic rates. There is growing evidence that sea turtles exhibit
regional differences in somatic growth linked to alternative dispersal
patterns during the oceanic life stage. Yet, the role of habitat quality
and diet in shaping somatic growth rates is poorly understood. Here, we
evaluate whether diet variation is linked to regional growth variation in
hawksbill sea turtles (Eretmochelys imbricata), which grow significantly
slower in Texas versus Florida (USA), through novel integrations of
skeletal growth, gastrointestinal content (GI), and bulk tissue and amino
acid (AA)-specific stable nitrogen (δ15N) and carbon (δ13C) isotope
analyses. We also used AA δ15N ΣV values (heterotrophic bacterial
re-synthesis index) and δ13C essential AA (δ13CEAA) fingerprinting to test
assumptions about the energy sources fueling hawksbill food webs
regionally. GI content analyses, framed within a global synthesis of
hawksbill dietary plasticity, revealed that relatively fast-growing
hawksbills stranded in Florida conformed with assumptions of extensive
spongivory for this species. In contrast, relatively slow-growing
hawksbills stranded in Texas consumed considerable amounts of non-sponge
invertebrate prey and appear to forage higher in the food web as indicated
by isotopic niche metrics and higher AA δ15N-based trophic position
estimates internally indexed to baseline N variation. However, regional
differences in estimated trophic position may also be driven by unique
isotope dynamics of sponge food webs. AA δ15N ΣV values and
δ13CEAA fingerprinting indicated minimal bacterial resynthesis of organic
matter (ΣV < 2) and that eukaryotic microalgae were the primary
energy source supporting hawksbill food webs. These findings run contrary
to assumptions that hawksbill diets predominantly comprise high microbial
abundance sponges expected to primarily derive energy from bacterial
symbionts. Our findings suggest alternative foraging patterns could
underlie regional variation in hawksbill growth rates, as divergence from
conventional sponge prey might correspond with increased energy
expenditure and reduced foraging success or diet quality. As a result,
differential dispersal patterns may infer substantial individual and
population fitness costs and represent a previously unrecognized challenge
to the persistence and recovery of this critically endangered species.