Spatial and temporal variation in the biofilm communities on two cultivated kelp species

Kelp cultivation is gaining interest in the Salish Sea region for both commercial mariculture and habitat restoration applications. The selection of appropriate cultivation sites in coastal waters is essential for the establishment of restored kelp populations or successful mariculture harvests. Microbial communities which form biofilms on kelp surfaces are increasingly recognized as important links to metrics of kelp health. Yet there is little knowledge about the microbial communities associated with kelps produced in hatchery systems and how these communities change when the host is outplanted and grows at aquculture or restoration sites in coastal waters. Here, we characterized the microbial communities associated with two cultivated species of kelp, Saccarina latissmia and Alaria marginata, in British Columbia and Washington. We documented changes in microbial communities from seedstring stage throughout the growth and development of the hosts to provide a baseline understanding of temporal changes in the cultivated kelp microbiome. We also assess how environmental factors that vary between outplant sites affect kelp-microbial associations.