Dietary plasticity linked to divergent growth trajectories in a critically endangered sea turtle

Frontiers in Ecology and Evolution

Ecology and Evolution

Anne B. Meylan¹  Angela R. Stahl²  Matthew D. Ramirez²  Kelton W. McMahon²  Lyndsey N. Howell³  Wendy G. Teas⁴  Larisa Avens⁵  Jamie M. Clark⁶  Brian A. Stacy⁷  Donna J. Shaver⁸  Peter A. Meylan⁹ 

[1] Florida Fish and Wildlife Conservation Commission, Fish and Wildlife Research Institute, Saint Petersburg, FL, United States;Smithsonian Tropical Research Institute, Panama City, Panama;Graduate School of Oceanography, University of Rhode Island, Narragansett, RI, United States;National Marine Fisheries Service, Office of Protected Resources, NOAA Pascagoula Laboratory, Pascagoula, MS, United States;National Marine Fisheries Service, Southeast Fisheries Science Center, Miami, FL, United States;National Marine Fisheries Service, Southeast Fisheries Science Center, NOAA Beaufort Laboratory, Beaufort, NC, United States;National Marine Fisheries Service, Southeast Fisheries Science Center, NOAA Beaufort Laboratory, Beaufort, NC, United States;Cooperative Institute for Marine and Atmospheric Studies, University of Miami, Miami, FL, United States;National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Office of Protected Resources at University of Florida, Gainesville, FL, United States;National Park Service, Padre Island National Seashore, Corpus Christi, TX, United States;Smithsonian Tropical Research Institute, Panama City, Panama;Eckerd College, Natural Sciences Collegium, Saint Petersburg, FL, United States;

关键词: amino acid;    carbon isotope fingerprinting;    compound-specific isotope analysis;    Eretmochelys imbricata;    trophic position;    somatic growth;    spongivory;    sponge (porifera);   

DOI  :  10.3389/fevo.2023.1050582

 received in 2022-09-21, accepted in 2023-01-11,  发布年份 2023

来源: Frontiers

【 摘 要 】

Foraging habitat selection and diet quality are key factors that influence individual fitness and meta-population 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, United States versus Florida, United States, 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 nitrogen isotope 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 re-synthesis 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 typical 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.

【 授权许可】

Unknown   
Copyright © 2023 Ramirez, Avens, Meylan, Shaver, Stahl, Meylan, Clark, Howell, Stacy, Teas and McMahon.