Strategies of cold-hardiness in three species of Antarctic dorylaimid nematodes

Three species of free-living Antarctic fellfield nematodes, Eudorylaimus coniceps, E. spaulli and E. pseudocarteri exhibited differing degrees of both strategies of cold-hardiness; freeze-tolerance and freeze-avoidance. Bimodal distributions of supercooling points were obtained from monthly field samples of both E. coniceps and E. spaulli. Individuals found in the low group of this distribution (supercooling to <-15 °C) were capable of avoiding freezing by extensive supercoolint (to a mean temperature of ca-22 °C), sufficient to with-stand the environmental extremes of the maritime Antarctic. The high groups of both these species, and almost all E. pseudocarteri, were likely to have frozen at some stage during winter. Survival of freezing increased with the temperature at which nucleation occurred, and has been described by a Gompertz model. Estimates of the supercooling points at which survival fell to 50% were-10.4,-7.1 and-6.1 °C for E. coniceps, E. pseudocarteri and E. spaulli, respectively.