Antarctic Science



Papers—Life Sciences and Oceanography

Cold tolerance of the Antarctic springtail Gomphiocephalus hodgsoni (Collembola, Hypogastruridae)


Brent J. Sinclair a1p1 and Heidi Sjursen a2
a1 Department of Zoology, University of Otago, Dunedin, New Zealand
a2 Department of Terrestrial Ecology, National Environmental Research Institute, Silkeborg, Denmark

Article author query
sinclair b   [PubMed][Google Scholar] 
sjursen h   [PubMed][Google Scholar] 

Abstract

Cold tolerance of the springtail Gomphiocephalus hodgsoni Carpenter (Collembola: Hypogastruridae) was studied at Cape Bird, Ross Island, Antarctica (77°13′S, 166°26′E). Microclimate temperatures indicate a highly seasonal thermal environment, with winter minima <–39°C. Snow cover significantly buffers both minimum temperatures and cooling rates. Gomphiocephalus hodgsoni survives low temperatures by avoiding freezing. Mean low group supercooling points (SCPs) ranged from –35.4°C in October to –28.3°C in January. The lowest SCP measured was –38.0°C. The high SCP group was very small, making up only 18% of the population in January. In October, G. hodgsoni had a very high glycerol content (>80 μg mg−1 dry weight), although this declined rapidly to low levels (c. 7–10 μg mg−1 dry weight) in January. Quantities of glucose and trehalose were low during October, but steadily increased throughout the summer. Haemolymph osmolality was exceptionally high (up to 1755 mOsm kg−1) at the end of November, but this rapidly declined to c. 500 mOsm kg−1 by late December. The presence of thermal hystersis proteins was indicated by both osmometry on haemolymph samples and recrystallization inhibition studies of springtail homogenates. There was a strong relationship between glycerol content and SCP, but the relationship between haemolymph osmolality, SCP and carbohydrates is uncertain.

(Received October 16 2000)
(Accepted March 23 2001)


Key Words: crtoprotectants; glycerol; overwintering; recrystallization inhibition; supercooling point; thermal hysteresis.

Correspondence:
p1 Department of Zoology, University of Stellenbosch, Private Bag x1, Matieland 7602, South Africa celatoblatta@hotmail.com


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