| Summary: | Global warming occurs at elevated rates in the Arctic. Continued warming is predicted to cause ecosystem-wide cascading effects as boreal species expand into the region. However, current species distribution and knowledge of drivers affecting community structure are largely unknown, and little is therefore known about the resilience of Arctic marine ecosystems to environmental change. The West Greenland coast is north-south orientated, which provides an ideal setting to study the impact of climate change on ecosystem dynamics and species distribution. We used this coastline to investigated latitudinal changes in the rocky intertidal ecosystem along 12° of latitude, from the subarctic to High Arctic (60–72°N). Using 320 cleared quadrats we quantified patterns in rocky intertidal assemblage composition, biomass and coverage in six regions. We related the level and variation in assemblage composition, biomass and coverage to multiple latitudinal-scale environmental drivers. We show that across all latitudes, the intertidal assemblage is dominated by a core of stress-tolerant foundation species, and we describe the effects of the investigated environmental drivers, and demonstrate that although mean biomasses decreased >50% from south to north, local biomass in excess of 10 000 g ww m-2 is found even in north Greenland, demonstrating the patchiness of this habitat. The results furthermore show that the effect of small-scale variation in environmental characteristics may be of same magnitude as large-scale variation. Hence, using the latitudinal gradient in a space-for-time substitution, our results suggest that while climate modification may lead to an overall increase in the intertidal biomass in north Greenland, it is unlikely to drive dramatic functional changes in ecosystem structure in the near future. Our dataset provides an important baseline for future studies to verify these predictions for Greenland’s intertidal zone.
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