Role of Grazers in the Recolonization of Hard Bottom Communities in Kachemak Bay, Alaska Nick Harman Brenda Konar School of Fisheries and Ocean Sciences,

Role of Grazers in the Recolonization of Hard Bottom Communities in Kachemak Bay, Alaska Nick Harman & Brenda Konar School of Fisheries and Ocean Sciences, University of Alaska Fairbanks Kelp Forests High productivity Algae provide food for grazers Physical structure of algae provides shelter for inverts, fish, and marine mammals Dynamic - biological and physical disturbances can leave bare patches suitable for recolonization Grazing Can decimate kelp assemblages Lacuna vincta is a voracious grazer in Kachemak Bay Inverts known to graze small individuals 1)Macrograzers (>2.5 cm) cause a significant reduction in the recruitment of sessile organisms 2) Macrograzers cause a significant reduction in the survivorship of sessile organisms Hypotheses Study Site Experimental Methods Cage Control Cage Treatment Uncaged Control Boulder Sampling Boulders deployed at study sites in 2005 Percent cover of algae and sessile inverts monitored monthly during study period (20 months) using SCUBA Sessile Organism % Cover on Caged Boulders & Controls Deployed in 2005 * * * = p < 0.05 ** = p< ** Major Sessile Taxa % Cover on Cleared, Uncaged Boulders Deployed in 2005 Onchodoris bilamellata Density at Study Sites Conclusions Grazers did not impact recruitment of sessile organisms Mesograzers (< 2.5 cm) did impact sessile organism survivorship, clearing space for other colonists Predatory mesograzers impacted the system more than herbivorous mesograzers Acknowledgements West Coast & Polar Regions Undersea Research Center North Pacific Research Board SFOS & B&W Katrin Iken & Bodil Bluhm Divers: Angie Dubois, Casey Debenham, Ben Daly, Joel Markis, Heloise Chenelot, Caroline Jezierski, Phil Harman, Rob Chadwell, Patrick Baum, Sean Rooney, Dominic Hondolero, Will Smith