Giant Kelp Microbiome Altered in the Presence of Epiphytes - 2018

We conducted field surveys in which we sampled seawater and the epibiotic microbial communities of kelp laminae at two kelp beds in the Santa Barbara Channel. We used supersucker devices to sample microbial communities on kelp laminae lacking visual signs of epibiotic bryozoans (healthy laminae), and those with 20% or more bryozoan coverage (bryozoan laminae). In this way, we were able to compare the microbial communities on healthy kelp laminae to those on bryozoan laminae across kelp beds and sampling dates. Our results indicate that kelp-associated microbial communities are altered in the presence of epiphytic bryozoans, and reflect changes previously observed in other studies of stressed macroalgae. This observation suggests patterns of dysbiosis and opportunistic pathogenesis that may have implications for the health and productivity of foundational species of macroalgae. This study highlights new patterns in host-microbiome associations and reveals the importance of considering host source and condition when investigating the community dynamics of macroalgal microbiomes.