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article imageAre sharks adapting to the acidic oceans?

By Tim Sandle     Nov 6, 2014 in Environment
Some species of shark are at risk from rising levels of acidity in the oceans. To avoid the risks that high levels of carbon dioxide pose, the epaulette shark appears to have adapted physiologically.
The epaulette shark (Hemiscyllium ocellatum) is sensitive to acidification or the oceans. The shark is commonly found in tropical waters off Australia and New Guinea. Epaulette sharks have nocturnal habits and frequent shallow water on coral reefs or in tidal pools.
Increasing levels of acid in the seas is a consequence of increasing levels of atmospheric carbon dioxide. As carbon dioxide levels have risen in the air, the oceans have absorbed around thirty percent. This leads to a reduction in pH levels and this poses a risk to many marine creatures.
The epaulette shark can tolerate short periods of hypoxia (low oxygen levels in the environment), and it does so by hiding deep within the crevices of coral reefs where oxygen levels can reach very low levels. A similar pattern of behaviour also seems to occur as a result of rising water acidity.
Researchers from James Cook University in Queensland, Australia have studied sharks at different levels of water acidity for periods of up to 90 days. In doing so, key physiological measurements were taken from the sharks. The key parameters related to the blood, especially in relation to the uptake and delivery of oxygen. The findings indicating that the reef-inhabiting shark is capable of undergoing a physiological adjustment to cope with a lower water pH.
The study is of importance because understanding how marine animals adapt to challenging environmental conditions can help scientists to understand which species will fare well under future climate change conditions.
The findings have been published in the journal Conservation Physiology, in a report titled “product of its environment: the epaulette shark (Hemiscylium ocellatum) exhibits physiological tolerance to elevated environmental CO₂.”
More about Sharks, Acid, Acid rain, Carbon dioxide
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