Article**: Oceans and Wetlands.
In May 2001, the Stockholm Convention on Persistent Organic Pollutants (POPs) was adopted, which banned and restricted POPs, but POPs are still widespread in the environment. The impact of these toxic and bioaccumulative chemicals on the decline of marine mammal populations is a global concern.
In a study published in Environmental Science and Technology, researchers used the world's largest dataset of stranding marine mammals, combined with published and unpublished data, to analyse pollutant concentrations in 11 species of marine mammals stranded off the coast of the United Kingdom to quantify the spatiotemporal trends of chemical pollutants in these animals over a 30-year period and to identify the composition of pollutants that pose the greatest threat to species and regions.
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Studies have shown that pollutant concentrations in marine mammals stranded off the coast of the UK have declined across all species over the past three decades, however pollutant concentrations and rates of decline vary widely across species and geographic regions. Pollutants continue to pose a threat to biodiversity in some species and regions. For example, of individuals sampled between 2014 and 2018, 48% showed concentrations of pollutants that exceeded the toxicity threshold. Notably, pollutant concentrations were highest in long-lived toothed whales at the top of the marine food chain, such as killer whales (Orcinus orca), bottlenose dolphins (Tursiops truncatus) and white-beaked dolphins (Lagenorhynchus albirostris).It is significantly higher in animals stranded along more industrialized coastlines.
The results showed that the concentration of blubber pollutants varied greatly between and within species. The killer whale had the highest average concentration of each contaminant, and its total pollutant concentration was significantly higher than that of the grey seal (Halichoerus grypus), which had the lowest average concentration. Of all the contaminants analysed, PCBs declined at the slowest rate, were measured at the highest concentrations of all species, and posed the greatest risk to the health of marine mammals.
At current concentrations, POPs are likely to have a significant impact on the health of marine mammals, and more effective elimination and mitigation strategies are urgently needed to address this critical issue affecting global ocean health.
NoteBioaccumulationIt refers to the phenomenon that biological organisms absorb and accumulate foreign substances directly from environmental media or from the food consumed during growth and development. Toxic and harmful substances, especially POP persistent organic pollutants, accumulate in the higher members of the food chain through the food chain, so that the concentration of the harmful substances is much higher than the environmental concentration, this phenomenon is called bioaccumulation.
Finishing: SARA Review: Yujie.
Reference: Rosie S williams et al, spatiotemporal trends spanning three decades show toxic levels of chemical contaminants in marine mammals,environmental science & technology (2023). doi: 10.1021/acs.est.3c01881