Association of Polar Early Career Scientists

 

The name ‘Antarctica’ generally reflects an image of a large icy continent thoroughly covered with ice and snow. With this cover and below zero-degree temperature, nobody imagines the presence of lakes in Antarctica. But, in fact, there is about 2% ice free area which is home to many lakes in Antarctica. Climate change is not restricted to the scientific community rather becomes a global issue. Lake study help in identifying the effect of climate change on aquatic organisms. Antarctic lakes are well suited for such studies.

Lakes in Antarctica differ in composition, size, hold unique environmental settings for biological organisms, and vary from coastal to inland settings. They exist from hypersaline to freshwater lakes with varying degrees of temporal or permanent stratification. Most of the lakes are prominent and visible during summer time. During winters, lakes freeze. In some deep lakes, only the upper layer of water freezes that acts as insulator, preventing the lakes freezing to the bottom, thus sustaining life within it. Isn’t it amazing that life can somehow flourish in the coldest place on earth?

Technological advancement has made it possible to see what lies below thousands of meter of ice without having to physically go down beneath it. Using a technique called Radio Echo sounding, scientists have found lakes buried under and ice sheet thousands of meters thick. These lakes are known as ‘sub-glacial lakes’. Radio Echo sounding is an airborne technique that sends radio waves from aeroplane and collects the reflecting waves to detect the interface of ice/bedrock; ice/water etc. Lake Vostok is the largest among the identified approx 400 subglacial lakes, measuring 250km long, 50km wide at its widest point and covering an area of 12500km2 under the Russian Station in Antarctica. This fresh water lake is approx. 4000m under the surface of the ice.

Despite extreme conditions, life thrives in Antarctic lakes. These lakes are different from lakes in the rest of the world, both because of their biological diversity and because of the severity of the physical and chemical factors associated with them. In order to survive in these lakes, organisms must be able to withstand several stresses. Phytoplankton (and other organisms) in Antarctic lake ecosystems have to adapt to survive through many conditions. First, during the long dark winters with very low temperature, which limit Photosynthetically active radiations (PAR). During this time there are low nutrient levels and low oxygen levels. Then, this changes to austral summer with 24-hour sunlight and availability of high intensity PAR. During this time there are increased nutrients, oxygen and temperature. Change in photoperiod (that is continuous dark or light period) limits biological diversity in Antarctic lakes, which plays a major role in the Antarctic food web.

The study of Antarctic lakes and its organisms are very important since these lakes are natural laboratories for studying evolution of microorganisms, and their adaptations towards extreme conditions. The study of such cold-loving microorganisms not only enhances the understanding of the scientific community about the unique microbial world but also has applications in biotechnology. It is very interesting to note that about two hundred patents have been filed related to actual or potential commercial biotechnological applications based on Antarctic genetic resources. Antarctic microbes may have application in the fields of medicine, nanotechnology, energy production and agriculture. They are delicate ecosystems that quickly respond to climate change, indicating the indirect impact of human activities.

Swati Nagar blog1

Photo Courtesy: Priyankar Datta

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