The effect of feeding on specific soil algae on the cold-hardiness of two Antarctic micro-arthropods (Alaskozetes antarcticus and Cryptopygus antarcticus)

The effect of consuming terrestrial algae on the cold tolerance of two Anta rctic micro-arthropods was examined. From the results of preferential feedi ng experiments, seven species of Antarctic terrestrial microalgae were chos en and fed to two common, freeze avoiding Antarctic micro-arthropods: the s pringtail Cryptopygus antarcticus (Collembola: Isotomidae), and the mite Al askozetes antarcticus (Acari: Oribatida). Mites were very selective in thei r choice of food whereas the springtails were less discriminating. The ice nucleating activity of each species of alga was measured using an ice nucle ator spectrometer and a differential scanning calorimeter. Pure cultures of individual species of algae had characteristic supercooling points ranging from ca, -5 to -18 degrees C. The effect of eating a particular alga on th e supercooling point of individual micro-arthropods cultured at two differe nt temperatures (0 and 10 degrees C) was examined. Neither species showed a preference for algae with low ice-nucleating activity and there was no cle ar correlation between the supercooling point of food material and that of the whole animal. However, feeding on certain algae such as Prasiola crispa , which contained the most active ice nucleators, decreased the cold tolera nce of both species of arthropods.