Kelp Beds and Their Local Effects on Seawater Chemistry, Productivity, and Microbial Communities

Our research showed that kelp beds locally increased the pH, oxygen, and aragonite saturation state of the seawater, while seawater inorganic carbon content and total alkalinity were lowered. Kelp beds depleted nitrate and phosphorus concentrations, but enhanced ammonium and DOC concentrations. Kelp beds entrained distinct microbial communities, with higher taxonomic and phylogenetic diversity compared to seawater outside of the kelp bed, and kelp carbon fixation more than compensated for decreased phytoplankton production that occurred in their proximity. Thus, the diversity of pathways for carbon and nitrogen cycling is enhanced in proximity to kelp. This photograph illustrates the article “Kelp beds and their local effects on seawater chemistry, productivity, and microbial communities” by Catherine A. Pfister, Mark A. Altabet, and Brooke L. Weigel published in Ecology. https://doi.org/10.1002/ecy.279