Profiles of soluble carbohydrates and their adaptive role in maritime Antarctic terrestrial arthropods
The existence of seasonal changes in concentrations of water-soluble carbohydrates in arthropods (both freezing-tolerant and intolerant species) from Signy Island was demonstrated. Seasonal patterns of variation, imposed by seasonality of the maritime Antarctic environment, in the production of soluble carbohydrates in response to low temperatures and/or dehydration for a range of terrestrial arthropods were confirmed. The freshwater copepod Pseudoboeckellapoppei exhibited much lower levels of soluble carbohydrates, with glycerol as the main component, and smaller seasonal fluctuations relative to the four terrestrial species. The two Antarctic mites (Alaskozetes antarcticus and Gamasellus racovitzai) accumulated glycerol (as a single-component cryoprotective system), in agreement with previous work reporting increased glycerol levels and lowering of the supercooling point in A. antarcticus. In the case of G. racovitzai, increased levels of glycerol may function in a different manner. The larval dipteran Eretmoptera murphyi and the collembolan Cryptopygus antarcticus have complex multi-component cryoprotective systems involving trehalose that may be related to low temperature acclimation and dehydration. These findings are discussed in relation to published work on single and multiple cryoprotective systems, supercooling points and the involvement of dehydration as a complementary stress in overwintering insects.