How Do We Explore Collection: Introduction to Water Columns Investigations. Video courtesy of NOAA Okeanos Explorer Program.
Introduction to Water Column Investigation Lessons
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.