Soapbox Science

Looking back: Toxic PCB levels in European orcas and other dolphins

Guest blog by Paul Jepson, Institute of Zoology at the Zoological Society of London (ZSL), UK

Earlier in 2016 Scientific Reports celebrated its fifth anniversary. You can view our interactive infographic and blogs marking this occasion here.

As this fifth anniversary year draws to a close, we’ve got back in touch with authors from two popular papers from recent years.

Now that some time has passed, we wanted to know about their experience publishing with the journal, what impact they felt their research has had and if there’s been any surprises along the way.
Last week we posted an interview with Alex Greenwood, author of the study “Anti-NMDA Receptor Encephalitis in the Polar Bear (Ursus maritimus) Knut”.

In this blog, we’ve spoken another Scientific Reports author: Paul Jepson. In January 2016, Dr Jepson and his colleagues published the study “PCB pollution continues to impact populations of orcas and other dolphins in European waters” in Scientific Reports.

Here’s what he had to say about the research.

Could you give a brief overview of your study?

The few remaining killer whale populations in European waters have very low, or zero rates of reproduction, and are close to extinction in industrialised parts of Europe. Polychlorinated biphenyls (PCBs) are chemical pollutants which were banned in the EU in the mid-1980s, but after an initial drop in concentrations following the ban, they have now stabilized across Europe in humans, fish and wildlife.

The goal of the study was to assess the exposure to — and likely effects of — specific chemical pollutants including PCBs in European whales, dolphins and porpoises (cetaceans). We found that PCBs were at excessively high concentrations in the blubber of several marine apex predator species across Europe, including killer whales and bottlenose dolphins, and were associated with long-term and on-going population declines.

Our results suggest that much more work is needed to mitigate PCB contamination of the marine environment, and to comply with the Stockholm Convention that requires the reduction and eventual elimination of large sources of PCBs and other persistent organic pollutants.

What impact would you say your paper has had?

The paper was only recently published but it has been widely reported in newspapers and by other media, globally. The PCB issue — as based on our paper — also featured on the BBC current affairs programme Newsnight.

A public meeting about PCBs in killer whales and dolphins in Europe was held at the Zoological Society of London (ZSL) in March, where I spoke along with two other speakers. The meeting had the second largest audience for a ZSL public meeting ever and, after a lively Q&A session, Professor Ian Boyd, Chief Scientific Adviser at the Department of Environment, Food and Rural Affairs, closed the event.

This new cetacean PCB data has quickly fed into various international scientific and policy forums, including the Working Group for Marine Mammal Ecology (WGMME) of the International Council for the Exploration of the Seas (ICES). The recent ICES WGMME report (2016) concludes that PCBs pose the greatest threat to bottlenose dolphins and killer whales throughout the Northeast Atlantic region. The ICES also provide rigorous scientific advice to the Convention for the Protection of the Marine Environment of the North-East Atlantic (OSPAR) — including EU compliance with the Stockholm Convention.

Were any of your findings unexpected?

The main finding that very high PCB concentrations still persist in Europe — over three decades after the EU ban on PCB use / manufacture — has surprised a lot of people, including scientists who thought the ban would result in a gradual decline in PCBs in all biota. In fact, Europe has the highest PCB exposures in the marine environment globally. The very low reproductive rates in some of the highly PCB-contaminated resident/coastal bottlenose dolphins and killer whales are highly consistent with known PCB effects on reproduction. This is a very depressing finding, because if an apex predator population effectively stops reproducing, it will eventually disappear.

Another surprise was the very high PCB exposures in bottlenose dolphins and killer whales around the Iberian Peninsula. We have known that the Mediterranean Sea has been a pollution hotspot for many years, but the very high PCBs levels in bottlenose dolphins and killer whales on the Atlantic side of the peninsula also rather surprised us. Clearly action is urgently needed to dispose of large stocks of PCB-contaminated materials, especially in France and Spain.

Was there a particular reason you chose to publish in Scientific Reports?

The journal is highly respected and open access.  It also takes longer papers and so we were able to include more results and a longer discussion. After submission, the Scientific Reports review process was very rigorous but fair. The referee’s comments improved the final manuscript, including the statistical treatment of the data. Shortly before publication, the journal Press Office held an international telephone conference for science journalists to attend — this undoubtedly helped the paper to obtain the excellent and high-quality media coverage that followed publication.

Dr Paul Jepson is a Reader at the Institute of Zoology at the Zoological Society of London (ZSL) and is the main grant holder for the UK Cetacean Strandings Investigation Programme (CSIP) funded by the UK Government. He is a European Veterinary Specialist in Wildlife Population Health and has worked on pathological and other investigations into stranded marine mammals since 1993 and stranded marine turtles and basking sharks at ZSL since 2002.


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