Business as usual for Antarctic krill despite acidification of the ocean

The lead author of this study, IMAS Ph.D. student Jess Ericson, said long-term laboratory research was the first of its kind.

"Our study found that adult krill is able to survive, grow and mature when exposed to one year to the level of ocean acidification this century can expect," Ericson said.

"We raised adult krill in a laboratory tank for 46 weeks in sea water of various pH levels, including in the present, levels predicted in 100-300 years, and to extreme levels.

"We measure a series of physiological and biochemical variables to investigate how future ocean acidification can affect survival, size, fat storage, reproduction, metabolism and extracellular fluid in krill.

"Our results show that their physiological processes are largely unaffected by the pH level they are expected to face in the next century.

"The adult Krill we monitor is able to actively maintain the acid-base balance of their body fluids when the pH level of seawater decreases, increasing their resistance to ocean acidification."

Ms Ericson said the findings were important because krill was the main link in the Antarctic food chain.

"Ocean smoke caused by anthropogenic carbon dioxide emissions is expected to occur most rapidly at high latitudes, such as in the Southern Ocean.

"Krill is the main prey item for marine mammals and seabirds, and any decrease in their abundance as a result of ocean acidification can produce significant changes in the Southern Ocean and Antarctic ecosystem.

"Increasing ocean acidity is known to have a negative effect on various marine invertebrates, causing a decrease in mineralization or dissolution of calcium carbonate shells, decreased or delayed growth, increased delayed mortality and reproduction or abnormalities in offspring, including Antarctic krill embryo development.

"Our finding that adult Antarctic crill looks resilient to such conditions is an interesting and significant result.

"However, the changing persistence of krill in the oceans will also depend on how they respond to ocean acidification in synergy with other stressors, such as warming the ocean and decreasing sea ice," Ericson said.

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Further information:
Jessica. A. Ericson et al., Adult Antarctic krill proved to be strong in simulating high ocean CO2, Biology Communication (2018). DOI: 10.1038 / s42003-018-0195-3