Diatoms are a common type of photosynthetic microorganism, found in many environments from marine to soil; in the oceans, they are responsible for more than a third of the global ocean carbon captured during photosynthesis. This leads to a significant amount of sequestered carbon ending up in the sediments at the bottom of the ocean. In both freshwater and marine ecosystems, the base of the food web is comprised of a diverse community of phytoplankton that includes diatoms who can thrive in a wide range of temperatures. In the Southern or Antarctic Ocean, large populations of a particular diatom, Fragillariopsis cylindrus, dominate the phytoplankton communities.