The new Marine and Antarctic Studies Institute (IMAS) has found that Antarctic krill is resistant to growing ocean acidification because it absorbs more CO2 from the atmosphere due to anthropogenic carbon emissions.
Krill is one of the most widespread organisms on Earth and a critical part of the marine ecosystem of the South Ocean.
While previous studies suggest that some living conditions of the Antarctic krill may be threatened by acidification of the oceans, research published in Nature Journal Communications Biology found that adult krill was not largely influenced by ocean acidification levels predicted for the next 100-300 years.
Study leader, IMAS, Jess Ericson, states that a long-term laboratory trial is the first of its kind.
"Our study found that adult krill can survive, grow and mature when exposed for up to one year to the levels of ocean acidification that can be expected in this century," said Mrs Ericson.
"Breeding adult krill in laboratory tanks we have had 46 weeks in sea water with different levels of pH, including those at present, predictive levels up to 100-300 years and up to the extreme level.
"We measured a set of physiological and biochemical variables to see how future ocean acidification can affect survival, size, lipid stores, reproduction, metabolism, and extracellular krill.
"Our results have shown that their physiological processes have been largely influenced by the pH values that are expected to face the next century.
"The adolescent krill we were watching was able to actively maintain the acid-base balance of their body fluids because the pH levels of seawater have decreased, thereby increasing their resistance to ocean acidification."
Mrs. Ericson said that this finding is important because krill is a key link in the Antarctic food chain.
"The ocean acidification caused by anthropogenic carbon dioxide emissions is believed to occur most rapidly at high latitudes, for example in the southern ocean.
"Krill is a major subject for marine mammals and seabirds, and any drop in their numbers due to ocean acidification can lead to significant changes in the southern ocean and the Antarctic ecosystem.
"Increased ocean acidity is known to have a negative effect on a number of marine invertebrates, resulting in reduced mineralization or dissolution of the calcium carbonate shell, decreased or delayed growth, increased mortality and delayed reproduction, or abnormalities in offspring, including the embryonic development of the Antarctic krill.
"Our finding that adult Antarctic krill seems resilient to such conditions is therefore an interesting and significant result.
"But the survival of krill in the changing ocean also depends on how they react to ocean acidification in synergy with other stressors such as ocean warming and declines in sea ice," said Ericson.
The study also included researchers from the ACE CRC, Oceans and Atmosphere of CSIRO, Australian Antarctic and Aker Biomarine in Norway.
Image credit: Wendy Pyper.
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