Pollution might be the cause of a perplexing population decline in the Southern Ocean’s smallest but most important species.

The shrinking population of the tiny shrimp-like Antarctic krill is presenting scientists with a giant challenge.

The krill are a vital link in the Antarctic food chain and are the staple diet for predators from penguins to whales.

While still found in great abundance throughout the Southern Ocean, their numbers have decreased by up to 70 percent since the 1970s.

Dr Susan Bengtson Nash from the National Research Centre of Environmental Toxicology (EnTox), part of UQ’s Faculty of Health Sciences, wants to find out why.

In the first year of a three-year Australian Research Council Discovery project, Dr Bengtson Nash is visiting the Norwegian Institute of Air Research to examine 10 kilograms of Antarctic krill.

She is testing for a variety of persistent organic pollutants (POPs) – harmful chemicals that resist degradation and accumulate in the environment and in organisms.

“I’m looking at krill as the keystone species in Antarctic food webs,” Dr Bengtson Nash said.

“Most larger species feed either opportunistically or solely on the krill swarms that form during summer months.”

Once the chemicals accumulating in the krill have been identified, Dr Bengtson Nash will conduct toxicity tests with live krill at the Australian Antarctic Division in Hobart.

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