Ice algae on the underside of Arctic sea ice
The Deming research group focuses on microbial life within sea ice. This seems like a pretty esoteric topic until you consider the extent of sea ice in both polar oceans and the subpolar seas (such as the Baltic Sea) and the abundance of photosynthetic life there. The picture above by the Soviet researcher Ivan Melnikov is an excellent example of this. The long dark strands growing from the bottom of the ice are chains of diatoms, single celled photosynthetic organisms. At times the bottom of Arctic and Antarctic sea ice resembles a savannah turned upside-down, and like a savannah all of this photosynthetic biomass fuels a rich ecosystem.
Jody Deming often refers to sea ice as an “inverted benthos”, meaning that it in some ways resembles the seafloor (but upside-down). If we combine this idea with the savannah concept we can start to see why microbes play a critical role in maintaining all this growth. Soil, as any farmer can attest, is more than just dirt. In addition to the little bits of rock and organic debris that provide structure it contains a very active community of bacteria and archaea (single celled organisms that resemble bacteria but are evolutionarily as distant from bacteria as we are). These bacteria and archaea are responsible for providing many of the nutrients plants need for growth and for recycling old and dead plant material.
Exactly the same dynamic plays out in sea ice, with bacteria specially adapted to the sea ice environment providing nutrients to and recycling nutrients from diatoms and other phytoplankton. These diatoms in turn feed copepods, krill, and small fish, and through them larger and larger organisms. In the next post we will start to explore how Shelly and I will use the tools of molecular biology (namely the sequence identity of RNA, DNA, and proteins) to further our understanding of the role microbes play in maintaining rich polar marine ecosystems.
