Volume 93 Issue 37 | p. 26 | Concentrates
Issue Date: September 21, 2015

Elephant Seals Molt Accumulated Mercury Into The Ocean

Environment: Methylmercury that accumulates in the marine creatures’ hair causes spikes of the neurotoxin near breeding ground
Department: Science & Technology | Collection: Critter Chemistry, Sustainability
News Channels: Analytical SCENE, Environmental SCENE
Keywords: elephant seals, methyl mercury, molting, ocean contamination
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These young male elephant seals at Año Nuevo State Park unknowingly shed high levels of methylmercury with their fur.
Credit: Steve Ritter/C&EN
Young male elephant seals at Ano Nuevo State Park, California.
 
These young male elephant seals at Año Nuevo State Park unknowingly shed high levels of methylmercury with their fur.
Credit: Steve Ritter/C&EN
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A UC Santa Cruz researcher analyzes the mercury content of seawater.
Credit: Priya Ganguli
A woman lifts a tube from an array of tubes.
 
A UC Santa Cruz researcher analyzes the mercury content of seawater.
Credit: Priya Ganguli

A study suggests that seasonal spikes in methylmercury levels in the waters off Northern California may be caused by mercury-contaminated northern elephant seal fur (Proc. Natl. Acad. Sci. USA 2015, DOI: 10.1073/pnas.1506520112). Jennifer M. Cossaboon, Priya M. Ganguli, and A. Russell Flegal of the University of California, Santa Cruz, say this is a previously unrecognized transport mechanism for oceanic methyl­mercury. Neurotoxic methylmercury is a persistent pollutant that becomes increasingly concentrated in animals moving up the food chain. Scientists have long observed hot spots of oceanic methylmercury contamination near industrial sites, but not at Año Nuevo State Park near Santa Cruz. Thousands of elephant seals, which can be 14 feet long and weigh up to 5,000 lb, make a biannual pilgrimage to Año Nuevo. During the spring and summer months, they mate and give birth. In the winter, they shed their skin and hair in a mass molting. The researchers measured high levels of methylmercury in the molted material. Additionally, they found that methylmercury levels in the waters off Año Nuevo were greater than nearby coastal sites and spiked during the molting period.

 
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