How Do We Explore Collection: Introduction to Water Columns Investigations

Video courtesy of the NOAA Office of Ocean Exploration and Research. Download larger version (mp4, 71.7 MB).




Water Column Investigations using the CTD systems are part of the underway reconnaissance, as well as site characterization elements in the Okeanos Explorer strategy for exploring Earth’s deep ocean.

As you know, CTD stands for conductivity, temperature, and depth; but the Okeanos Explorer’s CTD system is capable of measuring many other physical and chemical properties of seawater, as well as collecting water samples for analyses in laboratories aboard the ship or ashore. A variety of individual instruments are combined in the CTD system, all of which are managed by electronic components that gather data and control mechanical elements of the system. Like multibeam sonar, the CTD system depends heavily upon modern computer technology to manage a very large amount of data in a very small amount of time.

Our CTD lesson for grades 5 and 6 is titled, “What’s a CTD?,” and is intended to reinforce a basic understanding of the concepts of salinity, temperature, and density, and how these parameters are related. In our lesson for grades 7 and 8, titled “The Oceanographic Yo‐yo,” students graph data from actual CTD casts aboard Okeanos Explorer, and measure temperature and pH in simulated CTD water samples to look for clues that may signal the presence of hydrothermal vents.

“A Quest for Anomalies” is our lesson for grades 9‐12, in which students use spreadsheets to analyze data from Okeanos Explorer’s CTD system, and generate graphs which they interpret for evidence of hydrothermal vent ecosystems. All of these lessons are easily related to actual events that took place aboard Okeanos Explorer during the INDEX‐SATAL 2010 Expedition, and you can use these events to give students a sense of the excitement that builds as data from CTD casts reveal clues to help explorers find undiscovered ecosystems.

In late June, CTD data showed anomalies that suggested the possible presence of hydrothermal vents nearby. On June 30, 2010, Okeanos Explorer’s ROV Little Hercules visited the site and found an active hydrothermal vent surrounded by yellow and black molten sulfur, multiple species of hot‐vent shrimp, a scale worm 10cm in length, and a patch of stalked barnacles. After departing from the vent, the ROV ascended the summit ridge and encountered fields of sulfide chimneys with vast aggregations of stalked barnacles at their base. Some chimneys were covered in white sulfide; some were venting clear fluid; and others were venting chemical mixtures that resembled black smoke. Images from this are a great example of how systematic CTD surveys can play a vital part in making very exciting discoveries.