Sea Ice Transition

The sea ice, easily accessible by snowmobile and tracked vehicle, was the primary collection site. Depths at collection sites ranged from 20 m to greater than 200 m. Large holes drilled into the ice permitted access to the water below.

A dynamic range of environments exist below and within the the sea ice. The sea ice itself, which is interwoven with highly saline brine channels, supports a diverse and abundant community of microorganisms, often at concentrations much higher than the water below. Sea ice microbial communities may be important contributors to the annual phytoplankton blooms that occur each spring alone the edge of the sea ice retreat. Thus, UV may play a significant role in the productivity of such processes. The spectral properties of such ice is also important and the transmission of light through the ice was measured.

In addition to the sea ice, the water column contains an abundant mixture of microorganisms and larger plankton. Blooms of Phaoecystis sp. and diatoms were observed under the ice and heterotrophic bacterial production was high as well. In the benthos near Cape Evans and McMurdo Base many organisms make a living within the photic zone. Sea urchins, anemones, sea stars, red algae, and green algae all exist within the photic zone.