NOAA Teacher at Sea
Aboard NOAA Ship Oregon II
July 23 – August 10, 2018
Mission: Long Line Shark/ Red Snapper survey Leg 1
Geographic Area: 30 54 760 N, 76 32 86.0 W, 40 nautical miles E of Cape Lookout, North Carolina
Date: August 5, 2018
Weather Data from the Bridge:
Wind speed 11 knots,
Air Temp: 30.c,
Visibility 10 nautical miles,
Wave height 1 foot
Science and Technology Log
While our main mission aboard the NOAA Ship Oregon II is to survey and study sharks and red snapper, it is also very important to understand the environmental conditions and physical properties of the sea water in which these animals live. The CTD instrument is used to help understand many different properties within the water itself. The acronym CTD stands for Conductivity (salinity), Temperature, and Depth. Sensors also measure dissolved oxygen content and fluorescence (presence of cholorphyll).
Conductivity is a measure of how well a solution conducts electricity and it is directly related to salinity, or the salt that is within ocean water. When salinity measurements are combined with temperature readings, seawater density can be determined. This is crucial information since seawater density is a driving force for major ocean currents. The physical properties and the depth of the water is recorded continuously both on the way down to the ocean floor, and on the way back up to the surface. There is a light, and a video camera attached to the CTD to provide a look at the bottom type, as that is where the long line is deployed, and gives us a good look at the environment where our catch is made. These data can explain why certain animals gather in areas with certain bottom types or physical parameters. This can be particularly important in areas such as the hypoxic zone in the Gulf of Mexico. This is an area of low oxygen water caused by algal blooms related to runoff of chemical fertilizers from the Mississippi River drainage.
The CTD instrument itself is housed in a steel container and is surrounded by a ring of of steel tubing to protect it while deployed and from bumping against the ship or sea floor. Attached water sampling bottles can be individually triggered at various depths to collect water samples allowing scientists to analyze water at specific depths at a particular place and time. The entire structure is slowly lowered by a hydraulic winch, and is capable of making vertical profiles to depths over 500 meters. An interior computer display in the ship’s Dry Science Lab profiles the current location of the CTD and shows when the winch should stop. We have found this to be a tricky job, during large wave swells, as the boat rocks quite a bit and changes the depth by a meter or more. The operator must be very careful that the CTD doesn’t hit the ocean floor too hard which can damage the equipment.
The data collected while deployed at each station is instantly uploaded to NOAA servers for immediate use by researchers and scientists. The current data is also available the general public as well, on the NOAA website. Once safely back aboard the Oregon II, the CTD video camera is taken off and uploaded to the computer, The CTD must be washed off and the lines flushed for one minute with fresh water, as the salt water from the ocean can damage and corrode the very sensitive equipment inside. The instrument is also calibrated regularly to ensure it is working correctly throughout all legs of the long line survey.
I am having such a great time during my Teacher at Sea experience. In the 9 days aboard ship so far, we have traveled the entire coasts of Mississippi, Arkansas, Florida, South Carolina, and North Carolina. Never in my life did I think I would get an opportunity to do something like this as I’ve dreamed about it for decades, and now my dreams have come true. I’m learning so much about fishing procedures, the biology of sharks, navigational charting, and the science of collecting data for further study while back on land at the lab. I can’t wait to get home and spread the word about NOAA’s mission and how they are helping make the world a better place, and are advocating for the conservation of these beautiful animals!
Animals Seen: Sharpnose shark, Tiger Shark, Grouper, Red Drum fish, Moray Eel, Blue Line Tile fish