Temporal Trends of Alternative Halogenated Flame Retardants in Humpback Dolphins from the South China Sea

Abstract

Increasing human activities are altering marine ecosystems, which may have ramifications for predator feeding ecology and, thus, the degree of contaminant exposure. We conducted the first investigation of spatiotemporal trends for nine alternative halogenated flame retardants (AHFRs) and their relations with dietary variations in 128 humpback dolphins that were stranded along the northern South China Sea during 2003–2020. We detected the highest levels of seven major AHFRs in humpback dolphins compared with the results reported in cetaceans globally, indicating high AHFR contamination in coastal regions of South China. Dolphins that were stranded near urban regions generally contained higher AHFR concentrations than those that were stranded near rural areas, mirroring the environmental trends of AHFRs occurring in this area. Model-generated diet estimates suggested that humpback dolphins have reduced their consumption of high trophic-level prey in recent years, likely attributable to overfishing-induced prey decline in this region. After adjusting AHFR concentrations due to diet changes, the temporal trends of AHFR contamination in humpback dolphins were only slightly altered. Our results suggest that increasing discharges of AHFRs into the South China Sea during the 2000s and 2010s may have had a greater influence on AHFR trends in humpback dolphins than dietary shifts.

Supporting Evidence for the “Ten-Year Fishing Ban”: Different Modes of Fishing and Pollution Induce a Fish Diversity Decline between the Pearl River and Its Estuary

“…These results demonstrated that overfishing drove food web structure modifications and forced aquatic organisms to change their feeding habits, 35 such as the top predator Indo-Pacific humpback dolphins (Sousa chinensis) that reduced their consumption of high trophic-level prey due to an overfishinginduced prey decline. 36 Together with a fish biodiversity decline, a cascading top-down effect to lower trophic levels in aquatic ecosystems was also detected because overfishing produced a high-level predator reduction. 37 This could explain the beneficial predation effect of the positive feedback relationship between the keystone species S. chuatsi and shrimp, as well as zoobenthos constructed in the mixed trophic All data are log-transformed except for diversity and fish interaction index.…”

Estimation of Per- and Polyfluorinated Alkyl Substance Induction Equivalency Factors for Humpback Dolphins by Transactivation Potencies of Peroxisome Proliferator-Activated Receptors

“…, Baikal seal and human beings) have revealed that co-exposure of PFAS with other hazardous contaminants ( e.g. , TBT, PBDE 47, TBBPA, and TCBPA) exhibits additional effects on PPAR at concentrations relevant for humpback dolphins. ,, Actually, the populations of PRE humpback dolphin accumulated mixtures of PFAS congeners and other environmental PPAR ligands, such as alternative halogenated flame retardants, organotins, and PCBs. ,, Thus, the potential health risks of high-level PFOS and other PFAS congeners in PRE dolphins are of concern.…”

“…42,48,49 Actually, the populations of PRE humpback dolphin accumulated mixtures of PFAS congeners and other environmental PPAR ligands, such as alternative halogenated flame retardants, organotins, and PCBs. 14,38,50 Thus, the potential health risks of high-level PFOS and other PFAS congeners in PRE dolphins are of concern.…”

“…The Pearl River Estuary (PRE), which is in close proximity to the most economically developed region in China, continues to receive multiple anthropogenic pollutants, including PFAS, from the industrialized metropolis of over 70 million people. , The PRE inhabits the world’s largest population of Indo-Pacific humpback dolphins (Sousa chinensis) . The population is threatened with depletion and will inevitably be subjected to the cumulative effects of exposure to dangerously high levels of environmental pollutants. − Despite the highest hepatic PFAS concentrations in PRE humpback dolphins and their critical conservation status reported in our previous study, no published studies have established biomarkers of the toxicological effects of PFAS concentrations in them.…”

Insight into the Mechanism Underlying Dehalococcoides mccartyi Strain CBDB1-Mediated B12-Dependent Aromatic Reductive Dehalogenation

“…However, recent studies − still identified significantly high burdens of PCBs in marine mammals, collapsing the global population of killer whales by up to 50%. Meanwhile, huge quantities of less regulated emerging aryl halides, such as novel brominated flame retardants and polyhalogenated carbazoles, , have been loaded into the environment, which undermine our health and ecosystem further.…”