NOAA Teacher at Sea
Aboard NOAA Ship Okeanos Explorer
May 30 – June 14, 2019
Geographic Area of Cruise: U.S. Southeastern Continental Margin, Blake Plateau
Date: June 10, 2019
Latitude: 29°04.9’ N
Longitude: 079°53.2’ W
Wave Height: 1-2 feet
Wind Speed: 11 knots
Wind Direction: 241
Air Temperature: 26.7° C
Barometric Pressure: 1017.9
Science and Technology Log
As part of this mapping mission we are identifying places that may be of interest for an ROV (remotely operated vehicle) dive. So far a few locations have shown promise. The first is most likely an area with a dense mass of deep sea mound building coral and the other an area where the temperature dropped very quickly over a short period of time. But before I talk about these two areas of interest I would like to introduce you to some more equipment aboard.
CTD stands for conductivity, temperature, and depth. A CTD is sent down into the water column to collect information on depth, temperature, salinity, turbidity, and dissolved oxygen. Some CTDs have a sediment core on them so you can collect sediment sample. There is also a sonar on the bottom of the CTD on Okeanos Explorer that is used to detect how close the equipment is to the bottom of the ocean. You want to make sure you avoid hitting the bottom and damaging the equipment.
Yesterday we used a CTD because the XBTs launched overnight showed a water temperature change of about 4°C over a few meters change in depth. This is a HUGE change! So it required further exploration and this is why we sent a CTD down in the same area. The CTD confirmed what the XBTs were showing and also provided interesting data on the dissolved oxygen available in this much colder water. It sounds like this area may be one of the ROV sites on the next leg of the mission.
ROV stands for remotely operated vehicle. Okeanos Explorer has a dual-body system meaning there are two pieces of equipment that rely on each other when they dive. The duo is called Deep Discoverer (D2) and Seirios. They are designed, built, and operated by NOAA Office of Ocean Exploration and Research (OER) and Global Foundation for Ocean Exploration (GFOE). Together they are able to dive to depths of 6,000 meters. D2 and Seirios are connected to the ship and controlled from the Mission Control room aboard the ship. Electricity from the ship is used to power the pair. A typical dive is 8-10 hours with 2 hours of prep time before and after the dive.
Seirios lights up D2, takes pictures, provides an aerial view of D2, and contains a CTD. D2 weighs 9,000 pounds and is equipped with all types of sampling equipment, including:
- Lights to illuminate the dark deep
- High definition cameras that all allow for video or still frame photos
- An arm with a claw to grab samples, such as rock or coral
- Suction tube to bring soft specimens to the surface
- Rock box to hold rock specimens
- Specimen box to hold living specimens (many organisms do not handle the pressure changes well as they are brought to the surface so this box is sealed so the water temperature stays cold which helps the specimens adjust as they come to the surface)
My favorite fact about D2 is how her operators keep her from imploding at deep depths where pressure is very strong and crushes items from the surface. Mineral oil is used to fill air spaces in the tubing and electric panel systems. By removing the air and replacing it with oil, you are reducing the amount of pressure these items feel. Thus, preventing them from getting crushed.
D2 provides amazing imagery of what is happening below the surface. Like I said earlier, one of the areas of interest is mound-building coral. The mapping imagery below shows features that appear to be mound building coral and have shown to be true on previous dives in the area in 2018.
Mound-building coral (Lophelia pertusa) are a deep water coral occurring at depths of 200-1000 meters. They form large colonies and serve as habitat for many deep-water fish and other invertebrates. Unlike corals in tropical waters which are near the surface, Lophelia pertusa do not have the symbiotic relationship with algae. Therefore, they must actively feed to gain energy.
We saw whales today!!!! They went right past the ship on our port side and then went on their way. We weren’t able to see them too well, but based on their coloring, low profile in the water, and dorsal fin we think them to be pilot whales, most likely short-finned pilot whales. Pilot whales are highly social and intelligent whales.
There was also the most amazing lightening show last night. The bolts were going vertically and horizontally through the sky. I think what I will miss most about being at sea is being able to see the storms far off in the distance.
Did You Know?
You can build your own ROV, maybe with your high school science or robotics club, and enter it in competitions.
Mound Building Coral: NOAA, 2010, https://oceanexplorer.noaa.gov/explorations/10lophelia/background/biology/biology.html
Pilot Whales: American Cetacean Society, 2018, https://www.acsonline.org/pilot-whale