New study: Banned pollutants threaten Europe’s dolphins

Dolphins in Europe are still threatened by toxic chemicals banned as far back as the 1980s. The new study, published today in the journal Scientific Reports, also involved Morigenos researchers.

The research, based on long-term studies of more than 1,000 stranded or biopsied whales, dolphins and porpoises – collectively known as cetaceans – found that the blubber of killer whales (Orcinus orca), bottlenose dolphins (Tursiops truncatus) and striped dolphins (Stenella coeruleoalba) in Europe contain among the highest concentrations of polychlorinated biphenyls (PCBs) on the planet.

PCBs are a group of man-made chemicals previously used in the manufacture of products including electrical equipment, flame retardants and paints. High exposure to PCBs is known to weaken cetacean immune systems and markedly reduce breeding success by causing abortions or high mortality in newborn calves.

Dr. Paul Jepson, lead author and specialist wildlife veterinarian at ZSL’s Institute of Zoology, said: “The long life expectancy and position as apex or top marine predators make species like killer whales and bottlenose dolphins particularly vulnerable to the accumulation of PCBs through marine food webs. Our findings show that, despite the ban and initial decline in environmental contamination, PCBs still persist at dangerously high levels in European cetaceans.

“Few coastal orca populations remain in western European waters. Those that do persist are very small and suffering low or zero rates of reproduction. The risk of extinction therefore appears high for these discrete and highly contaminated populations. Without further measures, these chemicals will continue to suppress populations of orcas and other dolphin species for many decades to come.”

The research also identifies locations around Europe as particular global PCB ‘hotspots’, including the western Mediterranean Sea and south-west Iberian Peninsula. Concentrations of these chemicals tend to remain higher near industrial areas and densely-populated urban centres, making European waters especially vulnerable.

The waters off the Slovenian coast and elsewhere in the northern Adriatic Sea are no exception, as research included dolphins living there. Co-author and Morigenos president Tilen Genov said: “PCB concentrations in dolphins that we have been studying for the past 14 years are also fairly high. They aren't the highest among those studied, but nevertheless worrisome. Almost all of them exceed the levels known to cause physiological effects.”

“Co-author Robin Law said: “Our research underlines the critical need for global policymakers to act quickly and decisively to tackle the lingering toxic legacy of PCBs, before it’s too late for some of our most iconic and important marine predators.”

The study has already been featured in The Guardian, Independent, BBC, Daily Mail, ScienceNews and others.

Paper entitled ’PCB pollution continues to impact populations of orcas and other dolphins in European waters’ is available open access at:

www.nature.com/articles/srep18573

Nova raziskava: Prepovedana onesnaževala še vedno ogrožajo evropske delfine

Delfini v evropskih vodah so še vedno izpostavljeni toksičnim spojinam, ki so v Evropi prepovedane že od 80. let prejšnjega stoletja. V raziskavi, ki je bila danes objavljena v ugledni mednarodni reviji Scientific Reports, so sodelovali tudi raziskovalci društva Morigenos.

Dolgoletna raziskava, v kateri je bilo zbranih preko 1000 vzorcev živih in mrtvih kitov, delfinov in pliskavk (red Cetacea), je pokazala, da so koncentracije PCB spojin (poliklorirani bifenili) v tkivih evropskih ork (Orcinus orca), velikih pliskavk (Tursiops truncatus) in progastih delfinov (Stenella coeruleoalba) med najvišjimi na svetu.

Poliklorirani bifenili oz. PCB spojine so skupina umetnih kemikalij, ki so se nekoč uporabljale pri izdelavi različnih izdelkov, vključno z električno opremo, zaviralci gorenja in barvami. Gre za eno najbolj toksičnih snovi, kar jih je ustvaril človek. Znano je, da visoka izpostavljenost PCB spojinam pri morskih sesalcih povzroča oslabitev imunskega sistema in znatno zmanjšano rodnost. Slednja se lahko izraža kot povečano število splavov ali kot visoka smrtnost novorojenih mladičev.

Dr. Paul Jepson, vodilni avtor raziskave in veterinarski specialist iz Zoological Society of London je povedal: “Delfini, kot so velike pliskavke in orke, so plenilci na vrhu morskih prehranjevalnih spletov, živijo pa razmeroma dolgo. Zaradi tega so še posebej dovzetni za negativne vplive PCB spojin. Te spojine se namreč skozi prehranjevalno verigo kopičijo v velikih plenilcih. Naše raziskave so pokazale, da se je obremenjenost s PCB spojinami v morju po prepovedi sprva sicer zmanjšala, vendar se danes se zmanjšuje več in je še vedno na nevarno visokem nivoju.”

“V vodah zahodne Evrope danes živi le nekaj populacij ork. Tiste, ki so še prisotne, so izredno majhne in imajo malo ali nič prirastka. Verjetnost izumrtja za te majhne in z onesnaževali obremenjene populacije je torej zelo visoka. Brez dodatnih ukrepov bodo te strupene spojine še desetletja negativno vplivale na orke in druge vrste delfinov.”

Raziskava je prav tako identificirala evropske “vroče točke” ali “žarišča” za PCB spojine. Mednje spadata predvsem zahodno Sredozemlje in jugozahodni del Iberskega polotoka. Koncentracije teh spojin so navadno višje v bližini industrijskih območij in gosto poseljenih območij, kar pomeni, da so evropske vode še posebej izpostavljene.

Tudi slovenske vode niso izjema. V raziskavo so bili namreč vključeni tudi delfini, ki živijo ob slovenski obali in drugod v Tržaškem zalivu. So-avtor raziskave Tilen Genov, predsednik društva Morigenos in sodelavec na Univerzi na Primorskem, je povedal: “Koncentracije PCB spojin v tkivih delfinov, ki jih zadnjih 14 let preučujemo v Tržaškem zalivu, so prav tako razmeroma visoke. Sicer niso najvišje v tej raziskavi, a kljub temu zaskrbljujoče. Skoraj vse namreč presegajo vrednosti, ob katerih lahko pride do fizioloških odzivov v živalih.”

So-avtor raziskave Robin Law: “Če se želimo spopasti s to strupeno zapuščino naših nekdanjih dejanj, bodo morali globalni voditelji ukrepati hitro in odločno. V nasprotnem primeru se lahko zgodi, da izgubimo nekatere pomembne plenilce iz naših morskih ekosistemov.”

O novici so že poročali The Guardian, Daily Mail, ScienceNews in drugi.

Znanstveni članek z naslovom ’PCB pollution continues to impact populations of orcas and other dolphins in European waters’ je dostopen na:

www.nature.com/articles/srep18573