COLD TOLERANCE IN TARDIGRADA FROM DRONNING-MAUD-LAND, ANTARCTICA

Survival at low temperatures was studied in three species of Tardigrad a from Muhlig-Hofmannfjella, Dronning Maud Land, Antarctica. Both hydr ated and dehydrated specimens of Echiniscus jenningsi, Macrobiotus fur ciger and Diphascon chilenense had high survival rates following expos ure to -22 degrees C for ca. 600 days, and dehydrated specimens follow ing 3040 days at this temperature. In hydrated E. jenningsi, mortality increased with the duration of exposure from 7 to 150 days at -80 deg rees C, while mortalities of the two other species did not change. Hyd rated specimens of all species were rapidly killed at -180 degrees C, but all species exhibited good survivorship in the dehydrated state af ter 14 days at -180 degrees C. In conclusion, hydrated tardigrades are able to survive extended periods at low temperatures, and dehydrated specimens are even better adapted to survive overwintering on Antarcti c nunataks.