Being apex predator in the North Pacific , elephant seals compile gamy concentrations of mercury in their bodies , and when they shake off their pelt during their annual moult , they offload that toxic metal too . The findings , published inProceedings of the National Academy of Sciencesthis week , advise that the marine mammals might be contribute substantial amount of the environmental contamination to coastal ecosystems .
The most toxic shape of mercury , methylmercury ( MeHg ) , is a potent neurotoxin that ’s readily absorb into the eubstance of maritime organism . And through a physical process send for biomagnification , it becomes more and more hard as it make it up the food range of mountains . That means mercury concentrations in aquatic carnivores are 1 million to 10 million times gamy than the levels found in brine .
excretory product and fur moult by northerly elephant seal of approval ( Mirounga angustirostris ) are recollect to constitute a source of MeHg contamination at the base of nautical food chains . Previous work revealed gamey concentrations of Hg in sea king of beasts faeces , but because elephant cachet fast during most of their time on the beach , they ’re not excreting much at all . And there ’s also a seasonal element to MeHg level – hint that the main source might be seal fur . Elephant seals undergo an annual " ruinous molt , " shedding the entire out stratum of skin and hair . This so - called molted pelage comes off in sheets onto the beach .
To investigate , a trio from the University of California at Santa Cruz ( UCSC ) led by Jennifer Cossaboon collected saltwater near the northerly elephant seal rookery at Año Nuevo State Reserve in California . They compare the MeHg concentrations to that of other coastal sites where there are n’t large nautical mammal population . " Many studies have looked at biomagnification up the food chain , and we took that a stair further to see what happen next , " Cossaboon say in astatement . " Mercury is an element , so it never breaks down and goes off – it just interchange form . "
The team expose that MeHg assiduity were significantly high at Año Nuevo than at the other site during both breeding and molting season , but specially during the latter : MeHg grade were twice as high-pitched during breeding time of year and 17 times high during molting season . moreover , the team found high mercury density in the molted pelage samples they collect at Año Nuevo .
Coal electrocution and other such industrial emissions have significantly increased the amount of mercury in the marine environment . " This intragroup recycling back into the coastal environment just sum to the problem , " study joint author Russell Flegal ofUCSCadds . Methyl mercury horizontal surface in nearshore waters during molting season were greater than those observe in even the extremely urbanized San Francisco Bay estuary .
