L. Somme et T. Birkemoe, COLD TOLERANCE AND DEHYDRATION IN ENCHYTRAEIDAE FROM SVALBARD, Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology, 167(4), 1997, pp. 264-269
When cooled in contact with moisture, eight species of arctic Enchytra
eidae from Svalbard were killed by freezing within minutes or hours at
-3 and -5 degrees C; an exception was Enchytraeus kincaidi which surv
ived for up to 2 days. When the temperature approached 0 degrees C the
enchytraeids apparently tried to escape from the moist soil. The supe
rcooling capacity of the enchytraeids was relatively low, with mean su
percooling points of -5 to -8 degrees C. In contrast, specimens of sev
eral species were extracted from soil cores that had been frozen in th
eir intact state at -15 degrees C for up to 71 days. Compared to freez
ing in a moist environment, higher survival rates were obtained during
cooling at freezing temperatures in dry soil. Survival was recorded i
n species kept at -3 degrees C for up to 35 days, and in some species
kept at -6 degrees C for up to 17 days. Slow warming greatly increased
survival rates at -6 degrees C. The results strongly suggest that arc
tic enchytraeids avoid freezing by dehydration at subzero temperatures
. In agreement with this, weight losses of up to ca. 42% of fresh weig
ht were recorded in Mesenchytraeus spp. and of up to 55% in Enchytraeu
s kincaidi at water vapour pressures above ice at -3 to -6 degrees C.
All specimens survived dehydration under these conditions.