Work

Trophic Ecology of Loggerhead Turtles ( Caretta caretta ) in Southern Brazil: Insights From Stable Isotopes

Year: 2026

Type: article

Abstract: ABSTRACT This study aimed to investigate the trophic ecology of loggerhead turtles recorded stranded along the Paraná coast in southern Brazil. Carbon and nitrogen stable isotopes were analysed in muscle tissues from 20 loggerhead turtles and in 69 specimens representing 12 prey species (molluscs, crustaceans and teleost fishes). The δ 13 C values for turtles ranged from −19.5‰ to −16.0‰ (mean ± SD: −17.7‰ ± 1.2‰) and δ 15 N values ranged from 9.9‰ to 18.3‰ (mean ± SD: 14.2‰ ± 2.6‰). Juveniles (curved carapace length [CCL] < 83 cm) had lower mean values of δ 13 C (−18.4‰ ± 1.1‰) and δ 15 N (12.9‰ ± 2.4‰) than adults (−16.8‰ ± 0.7‰; 16.2‰ ± 1.3‰, respectively). Both isotopes were positively correlated with CCL. Bayesian mixing model analysis indicated that adults and juveniles mainly forage on fishes and crustaceans, although the most important prey species likely differ between age classes. This pattern is supported by the isotopic niche analysis, which showed little overlap. The results suggest that juveniles forage across different regions, including the oceanic zone, or have recently settled in the neritic zone while retaining the isotopic composition of the oceanic habitats. Loggerhead turtles displayed a varied diet, including several prey species that are bycaught by local fisheries, and they occupied different trophic levels depending on age class. These interactions between loggerhead turtles and fisheries present significant conservation implications for both the turtles and their prey.

Source: Aquatic Conservation Marine and Freshwater Ecosystems

DOI: 10.1002/aqc.70320