Distribution and freeze tolerance testing of nematodes around Cape Hallett and Terra Nova Bay

Nematode worms in Antarctica are adapted to survive extreme conditions. One species, Panagrolaimus davidi, is unusual in that it can survive extra as well as intra-cellular freezing. This study investigated whether all species of nematodes are as tolerant in such freezing and if so, what mechanism is used. In addition to this the study examined the distribution of nematodes in ice-free sites to determine how much exchange there is from site to site and to assess what characterisitics are important for the presence and absence of particular species. Soil samples were taken along 100 m transects (randomised sampling) at locations around Terra Nova Bay (Gondwana Station, Mario Zucchelli Station, Enigma Lake and at Adelie Cove) and Cape Hallett and the surrounding area (Cape Christie, Luther Lake, Salmon Cliffs and Redcastle). Nematode were extracted from the soil, concentrated and identified to species and counted under a microscope. The distribution and abundance along the transects was recorded along with descriptive data on the soil. Live cultures of a range of nematode species were established on nutrient agar for freeze tolerance and survival strategies to be investigated in the laboratory. The ability of nematodes to survive freezing at a range of sub-zero temperatures and at a range of cooling rates was tested and survival was assessed after a 24hour recovery period. Data loggers were installed during the field sampling period to measure the soil temperature at the surface, 2cm depth and 5cm depth.