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STUDYING THE MICROBIAL COMMUNITY IN THE ANTARCTIC WINTER

 

Looking south from Palmer Station across Arthur Harbor, Anvers Island, Antarctica, at the moon, 8:30 AM July 22. (Photo by James Walker, Raytheon Polar Services Company)

 
Along the Antarctic Peninsula, the ocean has warmed and sea ice has declined by 30% in response to climate change. Impacts on marine microbial communities are likely, and Ecosystems Center scientists are currently at Palmer Station to study the processes determining the species composition of the microbial communities during the winter season (mid-April to September).

This is the first time the MBL researchers – principal investigator Hugh Ducklow, senior research assistant Matthew Erickson and Brown-MBL graduate student Kristen Myers – will be able to obtain a full data set for the winter months. Their six-year study of the microbial community, conducted at the Palmer Antarctica Long-Term Ecological Research (LTER) site on Anvers Island, has been limited to the Southern Hemisphere’s summer months. The new winter data will tell Dr. Ducklow and his colleagues how winter and summer bacterial communities differ and what environmental factors govern the seasonal transition in microbial community structure.

The Ecosystems Center scientists will join colleagues Alison Murray, Joe Grzymski and Vivian Peng from the University of Nevada’s Desert Research Institute and Jean-Francois Ghiglione of Banyuls-sur-Mer, France, for two months at Palmer Station for their International Polar Year study, funded by the National Science Foundation. For several years, Dr. Murray has studied seasonal dynamics of microbial diversity in the Antarctic and more recently, metagenomics of the Antarctic microbial community, which provides information on diversity, energy-generating processes and adaptive capabilities, all features that are encoded in Antarctic bacterioplankton genomes.

The winter field season gives the team the opportunity to further document the microbial activities of the wintertime marine microbial communities, which will be determined using a suite of biochemical substrate uptake assays, quantitative microbial detection surveys and gene and protein expression profiling approaches.

The microbial ecologists are trying to understand the link between Antarctic microbial diversity and function in different seasons. This information is useful for understanding the impacts of climate change on the marine ecosystem. Dr. Murray’s previous research has shown that species composition and diversity of bacteria vary greatly during the strong Antarctic seasonal transitions. Now the scientists seek to find the differences between organisms that dominate the plankton during austral winter and summer. Genome sequences, RNA, and protein obtained from large-volume water samples will help provide the answers.

Dr. Ducklow and his colleagues will be at Palmer Station until early September. They will take water samples using their Zodiac boats within a two-mile radius of the station, then will incubate the samples in the light and add carbon to see if certain bacterial populations become dominant. Illuminating the water samples and adding carbon simulate the flux of organic matter into the ecosystem caused by the spring phytoplankton bloom. Information about the project is at http://genex2.dri.edu/

Palmer Station (65 South, 64 West) is operated year-round by the National Science Foundation. The International Polar Year (IPY) is a celebration of the 50th anniversary of the International Geophysical Year, held in 1957-58, which marked the beginning of international science in earnest in the Antarctic. Scientists from over 25 nations are currently conducting research in the Arctic and Antarctica during IPY (http://www.ipy.org/).


Kristen Myers and Matthew Erickson collect samples in Arthur Harbor from their Zodiac. (Photo by James Walker, Raytheon Polar Services Company)