Seasonal variation in the cold-hardiness of a free-living predatory antarctic nematode, Coomansus gerlachei (mononchidae)

• Published in: Polar Biology
• Main Author: Pickup, Jonathan
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Springer 1990
• Subjects: Antarctic; Antarc*; Polar Biology
• Online Access: http://nora.nerc.ac.uk/id/eprint/520737/; https://doi.org/10.1007/BF00238430

Coomansus gerlachei shows a strong seasonal variation in its supercooling ability, with most individuals freezing between -5° and -7°C, in a discrete high group, or between -15° and -26°C in a more diffuse low group. Increased cold-hardiness in winter is achieved by a strategy of freeze avoidance with an increase in the proportion of the population showing extensive supercooling ability. Smaller life-stages also exhibit lower supercooling points. Ice-nucleation at high sub-zero temperatures increases the probability of surviving freezing, a capacity which is enhanced in larger life-stages; adults and J4 stage juveniles show 50% survival at a supercooling point of -8.65° C. Laboratory incubations of field-fresh worms suggest that recent feeding is responsible for the movement between low and high groups. The cold-hardiness data for C. gerlachei provide interesting comparisons to the available data for microarthropods and create a precedent for seasonal changes between strategies of freezing tolerance and freezing intolerance in a field invertebrate population.