Rocky littoral macroorganisms that live between the high and low water marks were sampled in the summers of 1988 and 2007-2008 in Hornsund Fjord and along the adjacent Sorkappland coast (76-77°N). The same sampling stations and methodology were used to collect the samples. Over the last 20 years, the study area has been exposed to well-documented increases in air and sea temperature, increased windiness, and marked decreases in both the duration and extent of sea ice cover. The study revealed a twofold increase in the number of species found intertidally, a threefold increase in the biomass of macrophytes, and an upward shift in algae occurrence on the coast. Subarctic boreal species occupied new areas, while arctic species retreated. There were no species new to the area in 2007-2008, and all newcomers to the intertidal zone were noted in 1988 in the sublittoral zone. The relative stability of intertidal flora and fauna after 20 years is explained by the fact that the warm Atlantic waters (the main warming agent) are distant from the Sorkappland coast. Current observations show a marked change in the coastal belt biocenosis.

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