Krill business unusual under 'business as usual'

An Antarctic krill (Euphasia superba).
Larval development in Antarctic krill (Euphausia superba) will be affected by higher carbon dioxide concentrations. (Photo: Russ Hopcroft)
Ocean acidification could have a devastating impact on Antarctic krill according to a pilot study conducted by the Australian Antarctic Division.

The study, led by krill biologist Dr So Kawaguchi, in collaboration with Dr Haruko Kurihara and Professor Atsushi Ishimatsu of Nagasaki University, Japan, involved incubating krill eggs in sea water under three different carbon dioxide (CO2) concentrations: current CO2 levels – 'control', CO2 levels expected in 100 years time under a business as usual emissions scenario – 'medium', and CO2 levels expected in 300 years time under a business as usual emissions scenario – 'high'.

'As this was a pilot study, we wanted to determine the range of CO2 concentrations, if any, where we would see an effect,' Dr Kawaguchi said.

The study looked at the first four developmental stages of krill larvae after hatching.

In the control tank the eggs hatched and each larval stage developed and behaved normally. In the medium CO2 tank the eggs hatched, but development through the larval stages was limited – as the larvae progressed through each stage they became more inactive and were unable to swim to the surface of the tank. (In the wild, krill larvae ascend from 1000 m to the surface of the ocean – a developmental step necessary for the larvae to become juvenile krill). In the high CO2 tank, none of the eggs hatched.

Dr Kawaguchi and his team will now refine the research to look at different ranges of CO2 concentrations, the effects of elevated CO2 concentrations on other krill developmental stages, and the effects of changing temperature and food availability.

WENDY PYPER

Corporate Communications, AAD

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