Assessing the Health Impacts of Contaminants on Green Turtles (Chelonia mydas) Along the Southern Coast of Brazil

Abstract

Chemical pollutants pose a significant threat to marine ecosystems. Among these contaminants are trace elements and polycyclic aromatic hydrocarbons (PAH). Green turtles can be employed to evaluate the oceans' health due to their coastal habitats and exposure to multiple threats. This study investigated the anatomopathological findings and assessed the levels of non-essential elements and PAH in the organs of green turtles along the Paraná coast in the South of Brazil. The animals analyzed were found stranded between August 2015 and December 2019, by the Santos Basin Beach Monitoring Project team (PMP-BS). Histopathological analyses were carried out, and the levels of Arsenic (As), Cadmium (Cd), Lead (Pb), and Mercury (Hg) and PAH (dry weight; mg/kg⁻¹) were evaluated. The data were stored in the SIMBA database (Aquatic Biota Monitoring System). Simple and multiple logistic regression models were used to verify the possible interactions between histopathological findings and contaminant levels, and Spearman's correlation coefficient was employed to assess the correlation between non-essential elements and the curved carapace length (CCL). A total of 86 specimens were analyzed. The main histopathological findings were systemic congestion and granulomatous infiltrate. Naphthalene was the most frequently observed PAH. Cd and As showed the highest levels, with Cd having more interactions with histopathological findings. Inflammation was observed in several organs and correlated with the presence of non-essential elements (As, Cd, Hg, and Pb) and PAH. These results suggest a link between tissue changes in green turtles and environmental contaminants. However, further research is necessary to understand the extent and range of these effects.