Impacts of Doliolids on the Marine Microbial Community off the Oregon Coast

Marine microbes drive global biogeochemical cycling and are critical to sequestering carbon dioxide from the atmosphere to the ocean. Predation on marine microbes by viruses and single-celled microbes is well documented, yet models of microbial mortality with these sources do not account for observations of microbial death. We examined how an understudied group of animals, pelagic tunicates, could feed on marine microbes using an internal mucous mesh. One group of pelagic tunicates, the doliolids, have the potential to reshape marine microbial communities when they bloom. We sampled doliolids off the Oregon Coast and characterized the diversity, taxonomy, and relative abundance of their marine microbes. We identified chlorophyll-containing taxa in the doliolids, suggesting their feeding on phytoplankton, marine microbes at the foundation of marine food webs. This work changes our understanding of links between larger and smaller planktonic species in the Oregon Coast ecosystem and will advance understanding of how grazing influences nutrient turnover and carbon sequestration within marine systems.