The South Sandwich Trench is the southern most trench on Earth and receives cold Antarctic Bottom Water. The inhabitants of this trench and that of the Weddell Sea thereby live in the coldest deepest (high pressure) habitats on Earth. Yayanos will test the hypothesis that the bacterial inhabitants of these deep sears are the most pressue-limited organisms on Earth. Prior results show conclusively that inhabitants of cold deep-sea environments have the greatest pressure sensitivities among known bacteria of the deep sea. These Earth inhabitants may be best suited for comparison with possible inhabitants on Europa's ocean. Yayanos and his colleagues will also study the bacterial inhabitants of the Kermadec-Tonga Trench. Tonga Trench is more stenotopic with respect to temperature and pressure than are the bacteria of the Marianas Trench that they have previously studied. This physiological change is believed to be caused by the slightly lower temperature whose influence is exaggerated in high pressure habitats.
