Cool critters: adapting to a warmer world
2005 will see the disappearance of the Biology program with the formalisation of the new strategic direction focussing on the priority programs:-
- Ice, Ocean, Atmosphere and Climate
- Southern Ocean Ecosystems
- Adaptations to Environmental Change
- Impacts of Human Activities in Antarctica
Those parts of the Biology program that have been investigating the impacts of global climate change on the Antarctic biota will continue to do so as part of the Adaptations to Environmental Change program and work on the roles of the Antarctic marine biota in global biogeochemical cycles will continue within the Ice, Ocean, Atmosphere and Climate and Southern Ocean Ecosystems programs.
The Biology program has been composed of a small research group within the Australian Antarctic Division and a much larger group of Australian and overseas scientists working together investigating marine, terrestrial and lake ecosystems.
The two main questions focused on by Biology and some recent outputs –
What are the impacts of global climate change on the Antarctic biota?
A new virus is the cause of disease symptoms observed in plants on Macquarie Island. This is the first example of a terrestrial plant virus found in Antarctica, and the southernmost plant virus found. The results are of fundamental biological significance, and will enable investigation of how plant viruses evolve in such an isolated location.
A fungal infection of a moss on Heard Island has been characterised by gene sequencing, and the moss has also been identified by morphological and genetic analyses.
Analysis of Continuous Plankton Recorder data has shown that two small species of copepods have a biomass of around 270 million tonnes, nearly three times the current estimate of krill biomass.
Global warming is causing changes in terrestrial ecosystems, and the effects on terrestrial life are most likely to be greatest around regional boundaries like the Antarctic Polar Front Zone, where the sub-Antarctic islands are located. We are examining how sub-Antarctic organisms and ecosystems will respond to climate change. In doing so it will contribute to the conservation of these ecosystems. Simultaneous research on Heard, Kerguelen and Marion Islands in association with the French and South African Antarctic Programs focused on three main areas – plant development, shape and size, and variability and the composition of invertebrate communities. Preliminary data indicate that development times for key plant species between Kerguelen and Heard may differ by at least five weeks in some localities.
Heard Island environments are changing steadily as global climate change occurs. Recent fieldwork provides strong evidence of vegetation and habitat changes over the past 16 years and a sound basis for future monitoring in a dynamic environment sensitive to global change.
Research is underway to quantify the susceptibility of DNA in Antarctic plants to UV damage and investigate the effectiveness of protective and repair mechanisms. This will help predict how plants globally will cope with future climate change.
What are the roles of the Antarctic marine biota in global biogeochemical cycles?
Data from a new French-Australian collaboration involving investiation on the French Vessel l'Astrolabe, showed carbon dioxide uptake in Southern Ocean correlated dramatically with phytoplankton stocks.
A photographically illustrated guide to the over 550 species of Antarctic Marine Protists (phytoplankton and protozoa) has been published. This book brings together, for the first time, those single celled organisms that account for over 90% of the biomass of life in the sea, form the base of the marine food web and play a key role on the exchange of carbon dioxide between atmosphere and ocean.
In the last ten years it has become evident that viruses are common in the sea and lakes, occurring in concentrations of one to tens of millions per millilitre. They infect bacteria and phytoplankton and cause cells to die. In so doing they short circuit the cycling of carbon – one of the most important chemical cycles in nature, thereby preventing bacteria and phytoplankton being exploited as food by other organisms in the planktonic food chain. Preliminary work indicates high viral abundance in Antarctic lakes showing significant interannual variations which appear to be linked to local climatic patterns.
Dimethylsulphide (DMS) is a volatile trace sulphur gas that is produced by phytoplankton in ocean waters and sea ice. This substance escapes into the atmosphere and produces particles around which water vapour condenses to form clouds. At times this can be smelt from the deck of the ship. These sulphur produced clouds reduce temperatures by reflecting incoming solar radiation. DMS is implicated in global warming, since it has been suggested that as temperatures increase, more DMS must be emitted from the ocean in order to keep temperatures stable. Australian researchers have discovered that Antarctic sea ice organisms contain enormous quantities of DMS.
Exopolysaccharide (EPS) is complex sugar made by many microbes in the Antarctic marine environment. Low temperature stimulates EPS-producing bacteria in sea-ice and seawater to produce of EPS. The EPS is complex and of high molecular weight. A large proportion of complex organic matter in the sea-ice (especially in brine channels) and in seawater consists of EPS. The cold stimulated production of EPS suggests it has a protective role allowing enhanced survival at sub-zero temperatures.
More new publications for the Biology program:
- You can order a copy of Antarctic Marine Protists online
- Publication of the month: Some bacteria are more equal than others
Written by Harvey Marchant, 2004