Nesting Site Selection Fidelity and Hatchling Success of Sea Turtles in Polluted and Disturbed Coastal Zones

Abstract

Pollution of the coast and anthropogenic disturbance pose growing challenges for the reproductive ecology of sea turtles; however, impacts on nest fidelity and success of hatchling emergence have not been quantified along gradients of pollution and anthropogenic disturbance intensities. The current study evaluated the influence of pollution on nest fidelity, nesting frequencies, and hatchling emergence success of the loggerhead (Caretta caretta) and green (Chelonia mydas) sea turtles across five different coast zones that ranged in gradient from reference, least polluted beach to highly polluted industrial zones. The data were collected during four breeding seasons (2020-2023) in a total of 560 nest attempts and 2,847 nest observations. A significant decrease in fidelity was observed from 82.6 ± 4.2% in reference sites to 29.7 ± 9.1% in highly polluted sites (p < 0.001). Similarly, hatchling success also showed a decline from 71.3 ± 5.8% in reference zones to 19.2 ± 9.7% in highly polluted zones. Mechanistic influences included sand temperature, microplastics, nighttime light pollution, and human interference (R² = 0.81). Pollution-induced warming of the sand negatively affected the incubation success of the nests, while nighttime lighting interfered with nest orientation and hatching emergence.