Northern elephant seals’ fur builds up mercury toxicity from the animals’ prey and contributes to increasing mercury levels on California coasts during molting season, new study suggests.
Researchers explained that when mercury reaches the sea it gets transformed into an even more harmful compound called “methylmercury” by the fish and other sea animals. Methylmercury is a neurotoxin which can wreak real havoc into the brain of small creatures, but it can also harm humans with weakened immune systems such as the elderly and small children or pregnant women.
The research team explained that mercury is introduced into the environment through industrial mercury-laden waste water or the toxic gases released by vehicles in the air. Next, mercury gets carried to the ocean via waterways, but it was a mystery how it could reach some stretches of the Californian coast without a visible polluter around.
Scientists observed in the 1970s that the mussel breeding grounds off the coast of the Golden State coast in the Año Nuevo State Reserve showed unusually high levels of methylmercury. Back then, researchers had different theories but most of them believed that the situation may be linked to the elephant seals and sea lions which thrived in the region.
On the other hand researchers in the 1970s didn’t have the necessary equipment to detect mercury in the animals, and the idea remained a simple hypothesis until this year. San Diego State University researchers came across the hypothesis and planned to test it with help from modern-day technology.
Researchers had a feeling that the theory may be correct because in Año Nuevo coastal mercury levels were unusually high and no industrial pollution sources was detected nearby. The team found that deep sea mercury is carried to coastal areas by contaminated seals, which shed the chemical into the coastal water through their molt.
Jennifer Cossaboon, lead author of the study, noted that other scientists have long known that the seals may be to blame but they didn’t know how exactly the animals contributed to rising mercury levels in the area.
Cossaboon and her fellow researchers took water samples from Año Nuevo, and tested elephant seals for mercury intoxication. They learned that methylmercury these animals accumulate from their prey finds its way out of their bodies through their fur.
This is way molting season was associated with a spike in mercury levels along the California coastline where elephant seals return to breed and shed fur.
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