Kelp Density - Pacific Rim

This program measures kelp density from annual dive transects during August and September at a number of sites in the Broken Group Islands of Pacific Rim National Park Reserve. Kelp species assessed include Agarum spp., Macrocystis pyrifera, Eisenia arborea, Pterygophora californica, Saccharina spp. and Desmarestia spp. Kelp forests are phyletically diverse, structurally complex and highly productive ecosystems in temperate rocky marine coastlines, thereby providing a suitable suite of measures indicative of subtidal ecosystem health. On the west coast of Vancouver Island, the return of foraging sea otters (Enhydra lutris) and their effect on sea urchin populations have had different effects, depending on kelp species composition (perennial versus annual). Status for this measure is assessed by comparing observed perennial and annual kelp densities to the literature derived thresholds in areas where sea otters are present. Objectives are to monitor fluctuations in kelp density in conjunction with monitoring abundance of the main grazer, the Red sea urchin (Strongylocentrotus franciscanus), and oceanic climate conditions. The ultimate target of the kelp monitoring project is to document re-establishment of a fully functional ecosystem with the anticipated return of sea otters.