Survival of antarctic soil metazoans at −80°C for six years

A sample of the liverwort Cephaloziella varians was collected on 1 January 1999 at Rothera Point on the Wright Peninsula, Adelaide Island, western Antarctic Peninsula and was partially dried and then frozen at −80°C. The sample was rapidly defrosted to c. 10°C after six years and two months of storage at this temperature. Nematodes, tardigrades and a bdelloid rotifer present in the sample were found to have survived. Of the 159 nematodes recovered from the sample, 49 (31%) were alive: of the tardigrades and rotifers, two of 15 (13%) and one of 48 (2%) had survived, respectively. A Chi-square test showed that there was a significant association between nematode taxon and survival: a greater proportion of Coomansus gerlachei individuals were alive than of Rhyssocolpus paradoxus. A Chi-square test also showed that there was a significant association between phylum and survival: a significantly greater proportion of nematodes or tardigrades were alive than of bdelloid rotifers. We conclude that Antarctic soil metazoans are capable of surviving long-term exposure to low sub-zero temperatures and that there may be taxon-specific effects of freezing on survival.