Lack of recovery from disturbance in high-arctic boulder communities

High-arctic boulder communities that are impacted by anthropogenic and natural influences can result in the removal or scouring of sessile organisms leaving either open space or damaged organisms. This project asks how sessile communities recover after disturbances by determining (1) timing of recolonization, (2) grazer effects on recolonization, and (3) vegetative regrowth rates for encrusting sponges and corallines. Cleared boulders were monitored over 7 years to determine recolonization timing and grazer impacts. Vegetative regrowth rates were determined by monitoring partial clearings for 4 years. This study found that recolonization was slow with less than 10 % of the boulder surfaces being colonized after 7 years. Recolonization was so slow that it was difficult to ascertain grazer impacts, although it appeared there were no impacts. Lastly, this study showed that vegetative regrowth of sponges and encrusting coralline algae was fast. Sponges averaged 100 % regrowth after 2 years and corallines averaged 40 % after 4 years. Coralline regrowth was slower when exposed to higher sedimentation. This study showed that community recovery from disturbances is very slow in the Beaufort Sea, especially if entire organisms are removed. However, if removal is partial, recovery can be quicker, particularly in low sediment areas. Complete community recovery in this system after a disturbance may take a decade or more.