Megumi Shimizu is a graduate student studying microorganisms in marine sediment. She is currently on board the RVIB Nathaniel B. Palmer exploring seafloor communities in a once ice-covered region beneath the Larsen Ice Shelf. Over the next month, she will be updating us from the field.
I’m a PhD student interested in microorganisms and biogeochemistry of marine sediments; how the metabolisms of microorganisms interacting with the surrounding environment, the chemical components in sediments. Microorganisms in subseafloor are universally important because of its large biomass. It is said 50% of prokaryotes are living under the seafloor. This biomass makes large carbon and nutrients reservoir, which are important in biogeochemical cycle. For example, microorganisms play the role of organic carbon decomposition in sediments, as a result, carbon dioxide and methane are produced. In contrast, carbon dioxide and methane are also consumed by microorganisms called chemolithotrophs and methanotrophs in sediments. Therefore, understanding microorganisms in sediments; who they are, what are they doing, is important to reveal the details of global biogeochemical cycle and accurate estimate of budgets (amount of elements converted to different forms of chemicals for example, amount of carbon dioxide converted into organic carbon by carbon fixation). In addition, how microbial community response to environmental changes such as climate warming is also important in terms of the influence of global elemental cycles.