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10 Tuesday May 5 2015 ENVIRONMENT WILDLIFE Mercury contaminating caribou lichen on Arctic coast Warming climate could increase presence of potent toxin By MEAGAN WOHLBERG A new study from the University of Alberta shows that the lichen eaten by caribou herds along the Arctic coast is being contaminated with mercury from the marine ecosystem. The study looked at two islands in the Arc- tic Archipelago - Bathurst and Devon Islands - and found that where there was open water during most of the year methylmercury con- centrations in lichen were higher with those levels being highest close to the coast and de- creasing as researchers moved inland. On Bathurst Island which was near those openwaterareaswesawreallyelevatedconcen- trationsandenrichmentofthatmethylmercury over soils in just those coastal sites said Kyra St. Pierre a PhD candidate in the department of Biology who was lead author on the study. The pattern showed enrichment of close to 100 times moving inland toward the coast - strong evidence for a marine inuence on those concentrations. On Devon Island we saw none of that same patternSt.Pierrenoted.Itwaskindofaatline all across all of the sites which told us that the ocean didnt make a difference there probably because its locked in ice for most of the year. Methylmercury is a potent neurotoxin that bioaccumulates and thus magnies as it as- cends through the food chain. This study is the rst to make a clear link between mercury in the ocean and the toxin present in lichen consumed by caribou along the coast. St.Pierresaidbacteriaintheoceanproduce diamethylmercury a gaseous substance in surface waters. That gas then enters the atmo- spherewhereitistransformedbysunlightinto methylmercuryandisdepositedontothelichen. Aswellinorganicdepositsofmercurycom- ingfromcoal-redplantsasfarawayasChina due to the structure of global air currents are also deposited in the Canadian Arctic con- tributing to mercury concentrations in lichen. Lichen dont have any root system. Theyre a plant-like organism but actually a kind of fungus. So what happens is that lichen are dependent on the atmosphere for pretty well all of their nutrients. In that case it also makes it susceptible to airborne pollutants like mercury St. Pierre said. Though the study wasnt focused on cli- mate change specically St. Pierre said the results imply that more open water on the Arctic Ocean would likely lead to more mercury deposition on lichen. We may see that spatial pattern that we observed between the two islands gone altogether where theres no sea ice for longer periods for part of the year she said. And while caribou herds that eat lichen off the coast remain safe for human consump- tion more monitoring needs to be done to ensure their health - and the health of those who eat them as country food - is protected decades down the line. Intermsofthehealthofthecariboumercury isnt at a level thats going to impact them right now but in terms of a climate change perspec- tivewereallydontknowwhatthefutureofthe foodsupplyisgoingtobeforthemupthereSt. Pierre said. So if they become more or less de- pendent on lichen that would have an impact as well the open water is going to determine howmuchmercuryisactuallyinthoselichens. She said more research needs to be done to determine the source of mercury in lichen further inland which is at concentrations higher in lichen than other plant life. Lichen are dependent on the atmosphere for pretty well all of their nutrients. In that case it also makes it susceptible to airborne pollutants like mercury. Kyra St. Pierre University of Alberta A caribou feeds on lichen on the Arctic Coast. Open water is contributing to the deposition of methylmercury a potent neurotoxin on lichen along coastal areas in the North. PhotoMartinFortierArcticNet