Ocean acidification, caused by increasing amounts of atmospheric carbon dioxide dissolving in the ocean, poses a serious threat to marine ecosystems.

Increasing acidity affects the ability of some planktonic organisms to form shells, and is expected to change the species composition of plankton, with flow-on effects to higher levels of the food web.

Scientists at the Australian Antarctic Division and Antarctic Climate and Ecosystems Cooperative Research Centre have been studying the effects of ocean acidification on shell-forming, planktonic organisms, during research voyages to the Southern Ocean.

In recent shipboard experiments, planktonic communities were incubated in 650 litre ‘minicosm’ tanks, under carbon dioxide concentrations ranging from one to four times present-day levels. Responses of phytoplankton, protozoa, bacteria and viruses were measured both at the cellular and community levels, and are currently being analysed.

Early results from laboratory experiments indicate that increasing levels of carbon dioxide significantly affect the structural integrity of shell-forming plankton.

For more information:

Australian Antarctic Division and Antarctic Climate and Ecosystems Cooperative Research Centre, Simon Wright,

Tel: +61 3 6232 3338, simon.wright@aad.gov.au