Submarine hydrothermal systems include high-temperature (often up to 300°C) focus vent systems, low-temperature (>5-~120°C) diffusive vent systems, and low- to warm-temperature ridge-flank aquifers. Submarine hydrothermal fluids originate from seawater recharging into the oceanic basement—basaltic and peridotite rocks—underneath marine sediment. The recharging seawater is heated by magma underneath or by latent heat generated from the cooling of basement rocks. During circulation through basement rocks, recharging seawater is altered due to water-rock and biological reactions and become enriched in hydrogen, methane, and in some cases reduced sulfur species, all of which fuel chemosynthesis-based ecosystems. Access to sample and study hydrothermal habitats are provided by naturally formed hydrothermal vents or by seafloor observatories installed in ocean drilling boreholes.

Heat, turbidity and redox anomalies are commonly used to detect possible venting activities on the seafloor. Remotely operated vehicles and Towed Camera assist visualized sampling. With the ROV operated by Taiwan Ocean Research Institute (TORI) and the IONTU’s Towed Cam, now Taiwanese oceanographers and other scientists can perform precise imaging and sampling of submarine hydrothermal vents in tectonically active seafloor near Taiwan, the Philippines, and Indonesia.

This course is designed to connect this newly developing research field (in Taiwan) to students at NTU. In this class, students will learn techniques and instruments used to detect and sample hydrothermal fluid on the seafloor. A field trip will be arranged to sample hydrothermal fluids at Kueishantoa shallow hydrothermal vent field. We will seafloor sampling systems such as a multicorer available at NTU. Students will discuss the drastic differences between seawater samples and Kueishantao hydrothermal fluid and their biogeochemical implications. Furthermore, students will learn about recent advances in submarine chemosynthesis-based ecosystems.