Distinguishing between sea turtle foraging areas using stable isotopes from commensal barnacle shells

Area of Science:

• Marine Biology
• Conservation Science
• Isotope Geochemistry

Background:

• Understanding marine megafauna movement is crucial for conservation, especially for threatened sea turtles.
• Traditional methods like satellite telemetry are expensive.
• Barnacles on sea turtles record isotopic histories of their environment.

Purpose of the Study:

• To develop and validate a novel, cost-effective method for determining sea turtle foraging areas.
• To utilize barnacle shell isotopes (δ18O and δ13C) and growth rates as predictors of sea turtle habitat use.

Main Methods:

• Collected barnacles from sea turtles.
• Analyzed stable isotopes (δ18O and δ13C) in barnacle shells.
• Correlated isotopic signatures and growth rates with known sea turtle foraging areas.

Main Results:

• Successfully assigned sea turtles to foraging areas in Queensland, Australia, with high accuracy (86-94%).
• Effectiveness was demonstrated for areas separated by over 400 km.
• Barnacle isotopic data proved a reliable proxy for environmental conditions experienced by the host turtle.

Conclusions:

• Barnacle stable isotope analysis offers a cost-effective alternative to satellite telemetry for tracking sea turtle movements.
• This method can enhance understanding of foraging distribution, migration, and habitat use globally.
• The approach has potential applications for other marine taxa carrying epibionts.