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.
The RVIB Nathaniel B. Palmer. photo by Megumi Shimizu
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.
The latest edition of my Great Diagrams of Science series comes from a field near and dear to my heart- using stable isotope analysis to map a food web. Japanese scientists Wada, Mizutani, and Minagawa got the opportunity to study the feeding ecology of penguins in Antarctica, and were some of the first researchers to use stable isotopes for food web analysis. To travel so far and use what was at the time (1991) state-of-the-art technology, they must have received an impressively large grant. Their results played a part in revolutionizing how scientists study food web interactions, so the grant money was well spent in that regard.
However, it seems that none of it was spent on graphic design:
In the last few weeks, I’ve been busy with final exams and the start of my field season. Fortunately, many of the other shark bloggers have written about the important topics I’ve missed.
RTSea and Underwater Thrills both have written about how the Gulf oil spill can affect whale sharks, which are filter feeders who spend much of their time near the surface. Other sharks that are threatened by the oil spill include pups who use the Gulf’s shallow estuaries as nurseries, according to a CBS News piece. Underwater Thrills has some disturbing video of sharks in oil in the Gulf.
On a lighter note, the world is a better place since the Chum Buddy came onto the market.
A prehistoric nursery that used to be utilized by my favorite shark species (the Megaladon) has been discovered in Panama. The internet’s best source for prehistoric news is Laelaps.
Underwater Thrills has some exciting news- the National Geographic Channel has a new series about great whites that will be airing this summer.
RTSea has a post about new video showing how thresher sharks use their long tails to stun prey.
Fresh from Antarctica, this update comes to us from Dr. Douglas Nowacek, one of the Principal Investigators for the MISHAP project, by way of our field correspondent, Reny Tyson. Follow along with their adventures at Tagging Whales in the Antarctic Seas.