As mentioned in the first log entry of the expedition, the midwater contains much of the ocean’s biodiversity and MBARI’s use of ROVs to study this huge and unknown habitat has led to many discoveries.

Some of the most surprising discoveries made by MBARI’s midwater biologists involve giant larvaceans (Bathochordaeus). These pelagic tunicates thrive in waters about 50 to 300 meters deep in Monterey Bay, where they build large mucus houses that they use to filter food. These houses are discarded daily. The Midwater Ecology Group published findings that the discarded larvacean houses provide a massive transport mechanism for carbon to sink from the sea surface to the seafloor. Recently, MBARI researchers discovered that the sinking houses can transport microplastics to the deep sea as well.

Learn more about how larvaceans transport carbon and microplastics to the deep seafloor.