14. Studies of Ocean Acidification impacts on Antarctic krill at the Australian Antarctic Division

So Kawatuchi (1,2)*, Rob King (1), Natasha Waller (1), Blair Smith (1), Ashley Cooper (1)

1 Australian Antarctic Division, Kingston, Tasmania, 7050, Australia
2 Antarctic Climate & Ecosystems Cooperative Research Centre, Hobart, Tasmania, 7001, Australia

Background
Antarctic krill (hereafter krill) plays a key role in the Southern Ocean (SO) ecosystem being both the primary prey for most of the Antarctic mega fauna and important grazer of the primary production. How krill population may respond to environmental change including ocean acidification is an important management question for the future SO ecosystem, yet very little is known about the sensitivity of krill to ocean acidification. The Australian Antarctic Division (AAD) operates the only research aquarium where krill have been reared and successfully reproduced in captivity for research purposes. It has been conducting various international collaborative experiments on krill biology, physiology, behaviour, including impacts of ocean acidification on krill life history.

Methods
The aquarium system has a capacity to allow a range of experimental treatments, with 6 different levels of pCO2 and 3 levels of temperature, with 3 replicates. Experiments are being undertaken in various tank setups (250mL jars up to 200L tanks depending on the nature of the experiments). Krill at various life stages are being tested for various life history parameters such as hatch rates, development and growth parameters, mortality.

Findings
Our results so far collectively suggest that the early life stage (embryo) is the most vulnerable to increasing levels of pCO2, with their successful development showing sharp decline above 1250 atmpCO2, and showing zero hatch rate at 2000 atmpCO2. Results on the combined effects of elevated pCO2 and temperature on embryonic development are also expected to be presented.

Conclusions

The AAD has established a state of the art research aquarium for krill and is the only dedicated laboratory for experimental biology of krill outside the Antarctic continent. Our aim is to provide a comprehensive evaluation of the impacts of ocean acidification and warming on krill life history.