Work

Legacy organic pollutants are still a threat for resident dolphins of south-east Australia

Year: 2025

Type: article

Abstract: This study investigates the concentrations of persistent organic pollutants (POPs), specifically polychlorinated biphenyls (PCBs) and dichloro-diphenyl-trichloroethane (DDT) and its derivatives, in the blubber of three dolphin species stranded along the Victorian coast (Australia) from 2002 to 2022: Burrunan dolphins ( Tursiops australis, n=19 ), common bottlenose dolphins ( T . truncatus, n=6 ), and short-beaked common dolphins ( Delphinus delphis, n=7 ). ΣDDT concentrations generally exceeded Σ 9 PCBs across most individuals, with Gippsland Lakes (GL) Burrunan dolphins showing the highest ΣDDT concentrations (1400 to 598,000 ng/g lw), including a maximum of 598,000 ng/g lw in one individual—comparable to dolphins in heavily contaminated areas globally. DDE was the most dominant congener, reflecting its persistence. The DDE/ΣDDT ratio (0.46–1) indicates a historical DDT source, with possible remobilization from land-based stores. PCBs were primarily hexachlorinated congeners (PCB-138, PCB-153, and PCB-156), with extreme Σ 9 PCB levels found (up to 837,000 ng/g lw). Port Phillip Bay Burrunan dolphins and common bottlenose dolphins showed a decline in PCB levels over time, while GL Burrunan and short-beaked common dolphins exhibited minimal change. The widespread presence of hexachlorinated congeners suggests ongoing local PCB contamination despite the 1975 ban on PCB imports. This first multi-species POP assessment in the region reveals PCB and DDT levels that exceed health thresholds in 23 of 36 individuals, impacting 89% of critically endangered Burrunan dolphins. Despite limitations of stranded specimens, this study highlights significant, ongoing risks from banned PCBs and DDTs, underscoring the need for continued monitoring. • High DDT and PCB levels found in Burrunan dolphins. • Historical DDT and ongoing PCB contamination detected despite bans. • Pollutant levels exceed health thresholds, likely impacting endangered dolphins.

Source: Environmental Research

DOI: 10.1016/j.envres.2025.121045

Authors: Chantel S. Foord, Kate Robb, Dayanthi Nugegoda

Institution: RMIT University

Language: English

Topic: Toxic Organic Pollutants Impact

Subfield: Health, Toxicology and Mutagenesis

Field: Environmental Science

Domain: Physical Sciences

SDGs: Life below water, Good health and well-being

Open Access status: hybrid

Estimated APC paid: $3,880