Survival of freezing by free-living antarctic soil nematodes

Free-living microbivorous nematodes become numerically dominant in Antarcti c terrestrial faunas as environmental conditions become more severe, while also reaching very high levels of abundance in moist, vegetated habitats. N ematodes have little resistance to freezing via exogenous ice nucleation, s uch as would occur as their microhabitat freezes. We report the results of experiments testing the ability of seven maritime Antarctic nematode taxa t o survive freezing in small water droplets at high sub-zero temperatures. I solated individuals of these species possessed supercooling characteristics similar to those previously reported (supercooling points -6 to -25 degree sC). When frozen in water at -3 to -6 degreesC, most showed high (> 70%) su rvival both (i) after rapid cooling (1 degreesC min(-1)) to c. -60 degreesC followed by immediate rewarming, and (ii) when field for 7-12 h at either -10 or -30 degreesC, although the proportions surviving varied between spec ies. We propose that the ability to survive freezing while fully hydrated a t high sub-zero temperatures is one of the most important aspects of these species' survival tactics.