Kelp Wet Weight Measurements before and after Deployment in Caged Pycnopodia Field Experiment in the Sitka Sound Urchin Barrens during February 2023 (High latitude kelp dynamics project)

While the recently decimated predatory sea star, Pycnopodia helianthoides, may support kelp forests by consuming herbivorous sea urchins, less is known about their non-consumptive effects. We conducted a field experiment in three replicate sea urchin barrens in Sitka Sound, Alaska in February of 2023, where we deployed pre-weighed Macrocystis pyrifera blades at discrete distances on four metre radial cables from caged adult P. helianthoides and control cages and reweighed after 24 hours. Our results suggest the chemical cue of P. helianthoides elicits a localised, species-specific landscape of fear that suppresses grazing, and that the non-consumptive effects of P. helianthoides on sea urchin behaviour may be important for kelp restoration.