Competition And Recruitment In Southeast Alaskan Subtidal Kelp Communities

Abstract

Shallow subtidal rocky reefs in the Northeast Pacific host frequent physical and biological disturbances as well as multiple competing algal species, including kelps and algal crusts. Kelps serve a critical role in local ecosystems by generating primary productivity and essential fish habitat. While kelp forests rank among the best understood ecosystems in the marine environment, protected and subarctic systems remain largely ignored. Because of the importance of kelp habitat in Southeast Alaska, and the susceptibility of kelps to both disturbance and competition, I estimated the variability in kelp community structure of subtidal, kelp dominated reefs in the Lynn Canal and quantified kelp recruitment in response to both competing algae and bare space which included clearings, artificial reefs, and settlement tiles installed at different periods. Surveyed communities varied most within rather than among reefs. Kelps exhibited strong, rapid, variable and apparent taxa specific colonization potential to clearings, artificial reefs and settlement tiles installed from summer to late fall. Algal crusts imposed a near 100% inhibition of kelp recruits in the field and lab; however the strong colonization potential of kelps facilitated recruitment in the face of strong inhibition by algal crusts.