The Antarctic research program of the Australian Antarctic Division contributes to our understanding of global change in exploring natural resource sustainability, biodiversity conservation, human impacts on the Antarctic, and how
An excellent example of this program is the work being done by Dr So Kawaguchi and his team in the krill research aquarium.
Antarctic krill play a key role in the Southern Ocean ecosystem. They are the main prey for most Antarctic mega-fauna, and they are a major consumer of phytoplankton (tiny floating plants and animals in the ocean). It is therefore vital to better understand the biology of this key species as well as the potential impact of climate change on their existence.
The Australian Antarctic Division operates the only research aquarium in the world where a large number of krill have been reared and successfully bred in captivity for research purposes. The Antarctic Division uses the facility as a hub for various international collaborative experiments on krill life history, physiology and behaviour.
The aquarium routinely holds more than 10 000 live krill for research purposes. Because we have this captive krill population at
One of the focuses of the Division’s krill research is on obtaining life history information. This data is used to help manage the krill fishery, which is the largest wild Antarctic fishery. Our research also investigates the impact of climate change on key aspects of krill biology and ecology. For example, the aquarium allows us to study the effects of ocean acidification on krill (Kawaguchi et al., 2011). A recent experiment revealed that high levels of carbon dioxide (CO2) stopped krill embryos hatching. About 90% of the embryos’ development was disrupted at the gastrulation stage (an early phase in embryonic development) and no embryos survived to hatch at 2000 μatm pCO2 (partial pressure of CO2 – equates to 2000 ppm at atmospheric pressure) (Figure 1).
Although climate model projections suggest that the seawater pCO2 is unlikely to reach 2000 μatm within this century at the krill’s habitat depth range, it may exceed 1000 μatm under the IPCC IS92a scenario (Figure 2) (Kawaguchi et al. 2011). However, it is still difficult to estimate the CO2 sensitivities of krill in their natural habitat at various depths, and to what degree the species will be affected by climate change in the Southern Ocean in the coming decades.
The Antarctic Division is currently running experiments to find out exactly what the “tipping point” is in the pCO2 range between 1000 and 2000 μatm and to better assess the impacts of ocean acidification on krill. Ocean acidification studies on other krill life stages are ongoing. The research team’s ultimate goal is to undertake a comprehensive risk assessment of rising CO2 levels on the lifecycle of Antarctic krill for the next 100 years.
Figure 1. Effects of CO2 on krill development. (a) An embryo reared under current surface pCO2 developed into the limb bud stage; (b) an embryo reared at 2000 μatm pCO2. (Modified from Kawaguchi et al. 2011).
Figure 2. The vertical profiles of oceanic pCO2 GLODAP in the pre-industrial and present from the GLODAP data (black lines), and the model projections under the IP92a scenario (red line) and S650 scenario (blue lines) at 34.5°W, 65.5°S in the Weddell Sea. (Modified from Kawaguchi et al. 2011).
For more on the Australian Antarctic Division see www.antarctica.gov.au
The Antarctic Division’s The Australian Antarctic Magazine is published twice a year and is available online at http://www.antarctica.gov.au/about-antarctica/australian-antarctic-magazine/issue-20-2011