Kelp forests are among the most productive marine habitats, supporting biodiversity, food webs and ecosystem functioning. However, kelp forests are increasingly threatened by climate change, habitat degradation and overgrazing.
As part of Project Restore, a seascape restoration program in Sydney Harbour, enhancement of golden kelp (Ecklonia radiata) forests is being pursued by targeted removal of the long-spined sea urchin Centrostephanus rodgersii to increase habitat structure and associated ecological functions. We examined patterns of kelp re-establishment following urchin removal at four rocky reefs in Sydney Harbour. Since 2024, a total of 25.8 tonnes of urchins have been removed across the four sites. Our results indicate that kelp recruitment is dependent on the timing of urchin harvest, with recruits appearing from months to a year after urchin removal. After a year, kelp recruitment patterns at restoration sites did not differ from those observed at reference sites with extant kelp forests. These sites will continue to be monitored over the next two years to quantify the growth of these kelp recruits, the recovery of associated biodiversity, ecological functions and urchin densities. By analysing these recovery trajectories, Project Restore will provide crucial insights into the effectiveness of urchin control as a kelp enhancement or restoration tool.