Mercury levels in Arctic seals may be
linked to global warming
Researchers in Canada are reporting for the first time that high
mercury levels in certain Arctic seals appear to be linked to vanishing
sea ice caused by global warming. Their study provides new insight into
the impact of climate change on Arctic marine life.
Gary
Stern and colleagues note in the new study that Canadian Arctic ringed
seals, like many Arctic marine animals, have relatively high levels of
mercury.
However, researchers have never determined how these levels are
linked to sea ice extent and the resulting composition of arctic cod and
other prey containing mercury available to ringed seals.
The scientists analysed the mercury content in muscle samples
collected from ringed seals between 1973 and 2007. They then compared
the levels to the length of the so-called “summer ice-free season,” a
warm period marked by vanishing sea ice in the seals’ habitat.
They found that the seals accumulated more mercury during both short
(two months) and long (five months) ice-free seasons and postulate
(assume) that this is related to the seals’ food supplies.
Higher seal mercury concentrations may follow relatively short
ice-free seasons due to consumption of older, more highly contaminated
Arctic cod while relatively long ice-free seasons may promote higher
pelagic productivity and thus increased survival and abundance of Arctic
cod with the overall result of more fish consumption and greater
exposure to mercury.
Longer ice-free seasons resulting from a warming Arctic may therefore
result in higher mercury levels in ringed seal populations as well as
their predators (polar bears and humans).
Science Daily |