Hawksbill and green turtle niche overlap in a marine protected area, US Virgin Islands

Endangered Species Research
By: , and 

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Abstract

Studying how species interact with their environment and other co-occurring species are 2 main aspects of ecology. For marine turtles, ocean currents drive migratory routes and may determine the location of surrounding foraging grounds. As a result, circumglobal species like the hawksbill turtle Eretmochelys imbricata and green turtle Chelonia mydas adapt to diverse foraging habitats and employ varied feeding strategies. Dietary specializations may reduce competition for available food and space resources between co-occurring hawksbill and green turtles in US Virgin Island shallow reef habitats. This study analyzed isotopic data from immature hawksbill (n = 49; range: 18.7-49.8 cm straight carapace length [SCL]) and green turtles (n = 225; range: 24.1-69.4 cm SCL) to examine foraging niche. We used nitrogen stable isotope (δ15N) values as an indicator of trophic positioning and carbon stable isotope (δ13C) values as a habitat variable. Turtles were hand-captured across an 8 yr period (2012-2019), which facilitated the distinction of isotopic patterns in both the environment and among individual turtles. Understanding variations in habitat, community dynamics, and dietary consumption allowed us to utilize a 5 point framework to translate isotopic space to foraging niche. We found that the site’s relatively stable environmental conditions allow for isotopic overlap between hawksbill and green turtles despite the specialized feeding strategies each species employs. We also underscore the need to evaluate species-specific tissue turnover estimates as evidenced by the influence of tropical storms on recaptured turtle isotopic signatures. These findings inform our understanding of resource use for these imperiled species at our study site and are useful for future global isotopic comparisons.

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Publication type Article
Publication Subtype Journal Article
Title Hawksbill and green turtle niche overlap in a marine protected area, US Virgin Islands
Series title Endangered Species Research
DOI 10.3354/esr01276
Volume 52
Year Published 2023
Language English
Publisher Inter-Research
Contributing office(s) Wetland and Aquatic Research Center
Description 19 p.
First page 265
Last page 283
Country United States
Other Geospatial U.S. Virgin Islands
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