Pollution is bad for the sea life and so is global warming, but aquatic organisms can be resilient. However, even organisms tough enough to survive one major onslaught may find that a double whammy is more than their molecular biology can take.
A new study has found that even relatively low levels of heavy metal pollution can interfere with the metabolic processes of oysters, and that the effects of the pollution become particularly notable when oyster metabolism is also affected by high seasonal temperatures. The combined effect is strong enough to lead to fatal weakness and disease, adding a fundamental explanation for documented oyster declines in the wild. The effect also reveals an additional impact that warming coastal waters may have on cold-blooded organisms.
Investigating the mechanisms by which the heavy metal cadmium and temperature can each affect metabolic processes in oysters, a new report by a team headed by University of North Carolina at Charlotte ecophysiologist Inna Sokolova finds that both cadmium and temperature independently decrease the efficiency of metabolic processes in the oysters mitochondria the place where stored food is turned into the energy living cells run on.
The study also finds that cadmium can cause an increase in the production of reactive oxygen species dangerous metabolic by-products while higher temperatures hamper the cellular processes that normally prevent the compounds from causing damage. The findings will appear in the December issue of the Journal of Experimental Biology.
We are studying a combination of factors, said Sokolova. Essentially what we are trying to look at is how oysters that live in metal-polluted environments respond to an increase in temperature, including normal seasonal increases in the summer, and global climate change, which will add to the problems they are already having in warm periods.