Anchoring permits kelp to acquire an ecological niche in coastal oceans: A model analysis

Kelps (brown algae of the order Laminariales) are foundation species in coastal temperate oceans. As ecosystem engineers, they moderate local environments, provide habitats and food, and shape community structure. Despite their high rates of primary production, kelps overall growth rates are lower than co-occurring phytoplankton, and their competitive strength remains elusive. Here we developed a coastal ecological model including physical and biological processes to examine the most important factors for kelp survival. By comparing the distribution of kelp and phytoplankton, we found that kelp can accumulate larger biomass than phytoplankton because anchoring prevents them from being swept offshore away from high coastal nutrients. Slower water speed can eliminate kelp's advantage, which may explain the effect of El Niño and La Niña on kelp forests. Our simulation highlights the competitive ability of kelp and informs future in situ measurements and coastal ecosystem models.