The ice nucleation temperatures of thallus fragments of different macr
oalgal species were investigated. The samples were collected fi om the
littoral zone on a rocky shore in Trondheimsfjord, central Norway. Th
allus fragments of species growing in the zipper parts of the eulittor
al zone had lower ice nucleation temperatures than those of species li
ving in the lower eulittoral zone and in. the upper sublittoral zone.
Samples collected in the winter had lower nucleation temperatures than
samples from the same species collected in the summer, which indicate
s that the seaweeds are removing or inactivating ice nucleators as a p
art of their cold hardiness strategy.