Key Antarctic species under threat from ocean acidification

Antarctic krill
Antarctic krill (Photo: Stephen Brookes)
Two scientists peer into a tank containing krill in a labA scientist sits a a microscope while another looks at the image on a computer screen.Scientists looks nto a glass cabinet holding long bags of orange and green krill food

8th July 2013

New research, led by the Australian Antarctic Division, indicates serious challenges facing Antarctic krill - the primary food source for whales, seals and penguins - due to acidification in the Southern Ocean.

In the first study of its kind to explore impacts of acidification on Antarctic krill across the whole of the Southern Ocean, scientists paint a grim picture for the future of the species if carbon dioxide, or CO2, emissions are unmitigated.

The study, ‘Risk maps for Antarctic krill under projected acidification’ has been published in the distinguished international journal Nature Climate Change and shows that, if predictions are realised, vast areas of the krill habitat will become uninhabitable for reproduction.

Dr So Kawaguchi, lead author and krill biologist, said that Antarctic krill are the keystone species in the Southern Ocean and their fate is closely linked to the entire Antarctic ecosystem.

“A substantial decline in krill numbers would have disastrous implications not only for the health of the ocean environment but also on the future survival of the mammals and sea birds that rely on them.

“Antarctic krill are already experiencing changing climate stressors such as temperature rise, productivity change and declining sea ice.

“Now, our latest investigations clearly highlight the likely further impact that ocean acidification will have on these important crustaceans,” Dr Kawaguchi said.

For the past five years, Dr Kawaguchi and his colleagues have been looking at the effects of various stressors on Antarctic krill reproduction and development.

This new research identifies the consequences under four atmospheric CO2 scenarios, ranging from no emission mitigation to strong mitigation, on krill populations in the Southern Ocean.

The work has involved experiments in the Australian Antarctic Division’s krill aquarium, the only facility of its kind in the world.

“Disturbingly, our findings predict that krill will be unable to hatch or develop in vast areas of the Southern Ocean by the year 2300 if CO2 emissions continue to be released at the current rate,” Dr Kawaguchi said.

Magnitude of impacts at elevated levels of CO2 on egg hatch rates were obtained through experiments and statistically modelled at the Australian Antarctic Division.

This was then applied to predict risk areas for their hatching success by using the circumpolar projections of future CO2 levels in the Southern Ocean generated by our collaborator’s super computer at the Japan Agency for Marine Earth Science and Technology (JAMSTEC).

The related datasets are accessible at the Data Centre website.

The animation below by Lisa Roberts is a creative illustration of the life-cycle of krill.

[Video]