Roy Moffitt: Measuring Ocean Properties with the CTD, August 19, 2018

NOAA Teacher at Sea

Roy Moffitt

Aboard USCGC Healy

August 7 – 25, 2018

 

Mission: Healy 1801 –  Arctic Distributed Biological Observatory

Geographic Area: Arctic Ocean (Bering Sea, Chukchi Sea, Beaufort Sea)

Date: August 19, 2018

 

Current location/conditions:

Evening of August 19 – Edge of the Barrow Canyons in the Beaufort Sea

Air temp 32F, sea depth  185m , surface sea water temp  32F

 

Measuring Ocean Properties with the CTD

Scientists have a tendency to use acronyms to refer to select processes and measures.  The acronym heard the most, if not constant, on this trip has been CTD.  So here is my best attempt to give you a brief overview of what that “CTD” means and some of the measurements scientists are taking.

CTD Deployment

Deploying the CTD (Conductivity, Temperature, and Depth) probe, which is suspended in a metal “package” with Niskin water bottles

The acronym CTD stands for conductivity, temperature, and depth of the ocean water. This instrument, which takes a measurement 24 times a second, is attached to a large frame that includes big plastic bottles know as Niskin bottles. Nearly every time we stop the ship the CTD package (shown in the image above) is slowly lowered to just above the sea floor (or less depending upon the scientific interest at the site).   On the way back up, the Niskin bottles are filled with seawater from different pre-determined depths.  An electronic switch is triggered for each bottle at different depths so that the containers are sealed closed trapping water from that depth.  Once the package is back on board the scientists measure various properties of the water, including its salinity and oxygen content which will be used to verify and calibrate the electronic sensors on the CTD.

The three main measurements of the CTD represent fundamental characteristics of seawater. Conductivity (C) determines the salinity or the amount of salt in the water.  Electrical conductivity or how well an electric current can flow through the water gives an instant real time measurement of water salinity.  When combined with temperature (T) and depth (D) this gives a measure of the density of the water, and even tells us something about how the water is moving.

In addition to these physical properties, other sensors attached to the CTD provide information on the underwater marine life.  Phytoplankton is the base of the underwater food web and is an important indicator for the overall health of the local marine environment. Phytoplankton is too small to be seen individually without the aid of a microscope; however, scientists have found a way to test for its presence in water. Phytoplankton gets its energy, as all plants do, from the sun using the process of photosynthesis. One of the sensors on the CTD tests for chlorophyll fluorescence, a light re-emitted during the process of photosynthesis.  The amount of fluorescence measured can be used to determine the amount of living phytoplankton at different depths in the ocean.  Another sensor measures the levels of sunlight in the water.

The water samples from the Niskin bottles are used to determine many other properties of the water. One such property is dissolved carbon dioxide.  Just like the atmosphere, the ocean has its own carbon cycle.  We might hear of increased atmosphere CO2 levels associated with global warming.  Some of this CO2 is absorbed from the atmosphere at the surface of the ocean and some of the carbon from the ocean is also exchanged into the atmosphere. This carbon exchange rate between the air and sea helps regulate the pH of the ocean.  Tracking dissolved carbon dioxide measurements over time gives scientists additional physical measurements to track the overall health of the marine environment.  Scientists have been seeing increasing amounts of dissolved carbon dioxide in the ocean which can decrease pH levels making the ocean more acidic.  Small changes in the ocean pH can affect some marine life more than others upsetting the balance in the marine ecosystems.

 

The Exiting Pacific Ocean

At the moment scientists are doing even more CTD casts with a focus on ocean currents.   We are at the edge of the Chukchi Sea where the Pacific-origin water exits the shelf into the deep Arctic Ocean. Much of this happens at Barrow Canyon, which acts as a drain for the water to flow northward. Scientists are still uncertain what happens to the water after it leaves the canyon, so the survey we are doing now is designed to track water as it spreads seaward into the interior Arctic.

 

The Pressure of the Deep Sea

Most of the CTD casts during our time on the Healy have not exceeded 300 meters.  Lowering and raising the CTD from deeper depths takes a lot of precious time, and on this cruise the emphasis is on the upper part of the water column.  However, on August 18, we completed a cast 1000 meters deep.  In addition to collecting data, we were able to demonstrate the crushing effects of the deep ocean pressure by placing a net of styrofoam cups on the CTD to the depth of 1000 meters.  Styrofoam cups contain significant amounts of air. This is why the styrofoam cup is such a good insulator for a hot drink.  At 1000 meters deep, much of the air is crushed out of the cup. Since the pressure is equivalent around the cup, it is crushed in a uniform way causing the cup to shrink. Here are some images demonstrating the crushing power of the sea.  *Note: The big cup with no drawing is the original size.  This will be a great visual tool to bring back to the classroom.

shrunk cups

Styrofoam cups shrunken by the increased pressure of the deep ocean

 

Today’s Wildlife Sightings

A highlight today was not seeing but hearing.  I was able to listen in live on Beluga whales with the help of  deployed sonobuoys.  The sonobuoys  are floating hydrophones that transmit back what they hear with their underwater microphones.  Today they picked up the Beluga whales and their short songs.  I thought their calls sound like the songbirds from home and little did I know, this is why they are called the canaries of the sea!

 

Now and Looking forward

Tonight we saw 100s of Walruses mostly on the ice.  On Monday we will have a presentation about walrus from one of the scientists on board.  I look forward to sharing pictures and what I learned in the next blog.

Christine Webb: August 23, 2017

NOAA Teacher at Sea

Christine Webb

Aboard NOAA Ship Bell M. Shimada

August 11 – 26, 2017

Mission: Summer Hake Survey Leg IV

Geographic Area of Cruise: Pacific Ocean from Newport, OR to Port Angeles, WA

Date: 8/23/2017

Latitude: 48.19 N

Longitude: 125.29 W

Wind Speed: 7.9 knots

Barometric Pressure: 1021.70 mBars

Air Temperature: 62.1 F

Weather Observations: Partially cloudy

Science and Technology Log

For today’s science and technology log, I interviewed my roommate Tracie. You only have to talk to Tracie for five seconds to learn that she’s passionate about marine chemistry and marine biology and marine physics…all things marine. She’s the HAB (harmful algal bloom) specialist on board, and she’s been squirreled away in the chemistry lab every day collecting lots of great samples as we travel up the coast. Before we left Newport, she taught me a bit about algae by taking me to the beach to see some bioluminescent dinoflagellates. When we stomped in the water, the dinoflagellates would glow! It looked like puddles full of blue lightning bugs, and it was amazing. One of her quotes from that night was, “I imagine this is what unicorn footprints would look like if they were traipsing over rainbows.” Everyone should have the chance to see that at some point in their life. It gave me a taste of why it makes sense to be so passionate about algae. So, without further ado, here’s your chance to learn a bit more about HABs from my friend Tracie!

  1. What is a HAB, and why should we care about them?

HABs are phytoplankton that have negative consequences either for us or the ecosystem. Some can release neurotoxins that can be damaging to mammals (including humans), amongst other things. A harmful algal bloom (HAB) can also create a dead zone by a process called eutrophication. Bacteria eat the phytoplankton once they begin to die, which removes oxygen from the water.

  1. What makes it a bloom?

A “bloom” is when there is so much algae that the ecosystem can’t support it and they start to die off. There aren’t enough nutrients available in the water. Some people call this a “Red Tide.” There are certain species, such as Alexandrium spp., where even one cell per liter would be enough to create a harmful effect.

  1. What made you decide to study HABs?

During a lab in college, we were allowed to go to the beach and sample phytoplankton. When we got back to the lab with our samples, we found a huge amount of Pseudo-nitzschia spp. It releases a neurotoxin that gives mammals amnesiac shellfish poisoning. That year, we couldn’t eat shellfish and crab from our area because of this bloom. There’s no antidote to this toxin, and it affects the brain function of mammals who eat it. Whales died that year because they forgot how to breathe. This made me super interested in studying more about these types of species.

  1. What are you specifically hoping to find in your research aboard this cruise?

We’re trying to find where blooms start, how blooms begin, and follow them within the California Current system. It’s part of an ongoing study of the California Current system and how species are transported. California fisheries have been dramatically affected by HABs.

  1. Have you been finding what you need so far?

It’s been really interesting…we’ve seen quite a few Dinophysis species (which I find to be the cutest), and some really interesting Pseudo-nitzschia spp., but no blooms. Close to the coast, within 15 nm of shore, I see a lot more diversity in my samples. This is mostly due to upwelling.

  1. Has anything in your research so far surprised you?

There are very few species that I haven’t recognized, which is interesting because we’re so far north. We have fjord-like environments up here by Vancouver Island, so I expected there to be a higher abundance of phytoplankton up here than I saw.

  1. What is a common misconception about HABs?

The term “HAB” itself – they’re called harmful because they’re harmful to us as humans and to various industries, however – they provide a huge amount of support to other animals as primary producers and as oxygen producers.

They’re basically plants that can swim, and they’re all food for something. They’re not harmful for most things, so the name is kind of a misnomer. In defense of the HABs, they’re just trying to survive. Phytoplankton are responsible for around 50% of the world’s oxygen, and they’re the primary producer for marine and freshwater ecosystems.

  1. Anything else you want people to know?

There’s still a lot that we need to learn, and I would like everyone at some point in their life to see how beautiful these fragile organisms are and appreciate how much they contribute to our world.

  1. If you weren’t a marine chemist, what would you be?

I would write nonfiction about the beauty of the world around us. Or maybe I’d be an adventure guide.

  1. What are some fun facts about you that not a lot of people know?

My motto for life is “always look down.” There’s so much around us, even the dirt under our toes, that is so full of life and beauty.

My art is on Axial Seamount, 1400 m below sea level, 300 miles off the coast of Oregon! I drew an octopus high-fiving ROPOS the ROV that placed it there!

Also, I’m a high school dropout who is now a straight-A senior in environmental science at the University of Washington, Tacoma. Other people’s perceptions of you don’t control your destiny.

Here are a couple pictures of some of the HABs Tracie has seen during this trip (she took these pictures from her microscope slides):

329 D. fortii

Algae under the microscope: D. fortii. Image by Tracie.

329 hobbit house 2

Algae under microscope. Image by Tracie.

Personal Log:

Since today’s science log was about Tracie, I’ll feature her in the personal log too! She’s my partner in the ship-wide corn hole tournament, and we won our first-round game yesterday. Look at these awesome corn hole boards that were specially made for the Shimada!

IMG_20170822_153718727

Shimada corn hole board!

We mostly credit our fabulous war paint for the win. Today we play against our fellow scientists Lance and Tim. Wish me luck!

corn hole victory

Christine and Tracie celebrate corn hole victory

Another down-time activity that Tracie (and all the scientists) enjoy is decorating Styrofoam cups. The cool marine biologist thing to do is to sink them to very low ocean depths (3000+ meters). Apparently the pressure at that depth compresses the Styrofoam and shrinks it, making the cup tiny and misshapen but still showing all the designs that were put on it. I’m not kidding: this is a thing that all the marine biologists get really excited about. Tracie even decorated a Styrofoam head (the kind that cosmetologists use) in advance of this trip and brought it with her to sink. Look how cool it is – she’s an amazing artist!

IMG_20170824_171631958_HDR

Styrofoam head, decorated by Tracie, for shrinking

There are shrunken heads in the lab already from other people who have done this. Sinking Styrofoam is a legit marine biology hobby. Well, as the saying goes, “When in Rome…” so I worked on a Styrofoam cup today. I’m making a hake tessellation, which takes longer than you might think. Here’s what I’ve got so far:

IMG_20170823_051528993

Styrofoam cup decorated with hake tesselation

We’re having lots of fun at sea on this beautiful day. Someone just came over the radio and said there’s been a marine mammal sighting off the bow…gotta go!

Special Shout-out:

A special shout-out to Mrs. Poustforoush’s class in Las Vegas, Nevada! I just found out you’ve been following this blog, and it’s great to have you aboard. If you have any questions about algae (from this post) or about life on a ship, please feel free to e-mail me. I can hopefully get your questions answered by the right people. Work hard in Mrs. Poustforoush’s class, okay? She’s a great teacher, you lucky kiddos. Learn a lot, and maybe one day you can be a scientist and live on a ship too!

Beverly Owens: What Skills Are Important in Becoming a Scientist or Engineer? June 17, 2013

NOAA Teacher at Sea
Beverly Owens
Aboard NOAA Ship Henry B. Bigelow
June 10 – 24, 2013

Mission:  Deep-Sea Corals and Benthic Habitat: Ground-Truthing and Exploration in Deepwater Canyons off the Northeastern Coast of the U.S.
Geographical Area: Western North Atlantic
Date: June 17, 2013

Weather Data from the Bridge:
Air temperature: 17.60 oC (63.68 oF)
Wind Speed: 13.41knots (15.43mph)
Water Depth of current dive: approximately 1800 m (5905 ft)

Science and Technology Log

I have been amazed in watching the Science Crew (scientists and TowCam engineers) operate this week.  With any challenge that is presented, they work as a team to make minor adjustments, troubleshoot, and correct any issues that may arise. That got me thinking…what skills or characteristics are important in becoming an engineer or a scientist?

I surveyed the Science Crew, and based on their responses, have developed a list of skills important for scientists and engineers:

  1. Have a positive attitude.
  2. Be an excellent student. Learn to think independently.
  3. Be a good writer.
  4. Communicate well with others.
  5. Develop analytical thinking skills.
  6. Volunteer or become familiar with resources, like labs, museums, or other scientific institutions.
  7. Develop strong math skills.
  8. Develop computer skills or computer programming skills.
  9. Perseverance: If you make a mistake you can’t get down about it. You have to pick yourself up and try again.
  10. Curiosity: If you are curious, you’ll be passionate about what you’re studying, and will be able to communicate that to others. If you’re passionate, you will persevere and work through the challenges.

Personal Log

During my Teacher at Sea experience, I have had the opportunity to observe the Science Crew during many different activities. Below are some skills or characteristics that I have seen exhibited by the scientists and engineers involved in this research expedition.

  1. Work as a team.
  2. Cooperate: Get along with others.
  3. Be tenacious and persevere; be steadfast, never give up.
  4. Look at things from different perspectives; think “outside of the box.”
  5. Listen to and respect other people’s ideas.
  6. Focus on the task at hand.
  7. Think things through before jumping in.
  8. Come up with hypotheses or solutions and test them. If the solution doesn’t work, try another one.

As science teachers, we try to instill these traits in our students in the classroom. Whether it is completing a group project, conducting a lab, or taking notes, there is always opportunity to improve our science and engineering skills.

Did You Know?

One feature of the deep ocean is that this region of ocean is subject to very high pressure due to the tremendous weight of the water above. So, how about a demonstration?

Take one Styrofoam cup, decorate it, and send it over a mile deep in the ocean. What happens to the Styrofoam cup?

It shrinks! Why? Pressure in the ocean increases about 1 atmosphere for every 10 m increase in depth. The increased pressure compresses the air inside the Styrofoam, and the cup condenses. It’s the same reason why your ears start “popping” when you drive to an area of higher elevation, like the mountains, or fly in an airplane. In that case, increase in altitude means a decrease in pressure

Increased pressure at the bottom of the ocean caused the Styrofoam cup to shrink.

Increased pressure at the bottom of the ocean caused the Styrofoam cup to shrink.

Lesley Urasky: Smile and say, “Squid!”, June 20, 2012

 NOAA Teacher at Sea
Lesley Urasky
Aboard the NOAA ship Pisces
June 16 – June 29, 2012

 Mission:  SEAMAP Caribbean Reef Fish Survey
Geographical area of cruise: St. Croix, U.S. Virgin Islands
Date: June 20, 2012

Location:
Latitude: 18.1937
Longitude: -64.7737

Weather Data from the Bridge:

Air Temperature: 28°C (83°F)
Wind Speed:  19 knots (22 mph), Beaufort scale: 5
Wind Direction: from N
Relative Humidity: 80%
Barometric Pressure: 1,014.90  mb
Surface Water Temperature: 28°C (83°F)

Science and Technology Log

The cameras are a very important aspect of the abundance survey the cruise is conducting.  Since catching fish is an iffy prospect (you may catch some, you may not) the cameras are extremely important in determining the abundance and variety of reef fish.  At every site sampled during daylight hours, we deploy the camera array.  The cameras can only be utilized during the daytime because there are no lights – video relies on the ambient light filtering down from the surface.

Camera array – the lens of one of the cameras is facing forward.

Deployment of the array at a site begins once the Bridge verifies we are over the sampling site. The camera array is turned on and is raised over the rail of the ship and lowered to the water’s surface on a line from a winch that has a ‘quick release’ attached to the array.  Once over the surface, a deck hand pulls on the line to the quick release allowing the array to free fall to the bottom of the ocean. Attached to the array is enough line with buoys attached. The buoys mark the array at the surface and give the deck hands something to aim for with the grappling hook when it is time for the array to be retrieved.  Once the buoys are on deck, a hydraulic pot hauler is used to raise the array from the sea floor to the side of the ship.  From there,  another winch is used to bring the array on board.

Vic, Jordan, Joey, and Joe deploying the camera array.

When the array is deployed, a scientist starts a computer program that collects the time, position and depth the array was dropped at. The array is allowed to “soak” on the bottom for about 38 minutes. The initial 3-5 minutes are for the cameras to power up and allow any sediment or debris on the bottom to settle after the array displaces it. The cameras are only actually recording for 25 of those minutes. The final 3-5 minutes are when the computers are powering down.  At one point in time, the cameras on the array were actual video cameras sealed in waterproof, seawater-rated cases. With this system, after each deployment, every individual case had to be physically removed from the array, opened up, and the DV tape switched out.  With the new system, there are a series of four digital cameras that communicate wirelessly with the computers inside the dry lab.

We did have a short-lived problem with one of the digital cameras — it quit working and the electronics technician that takes care of the cameras, Kenny Wilkinson, took a couple of nights to trouble shoot and repair it.  During this time period, we reverted back to the original standard video camera.  Throughout the cruise, Kenny uploads the videos taken during the day and repairs the cameras at night so they will be ready for the next day’s deployments.

Squid (before being cut into pieces) used for bait on the camera array

Besides the structure of the camera array which is designed to attract reef fish, the array is baited with squid.  A bag of frozen, cut squid hangs down near the middle.  The squid is replaced at every site.

Adding bait to the camera array.

In addition to the bait bag, a Temperature Depth  Recorder (TDR) is attached near the center, hanging downward near the bottom third of the array. The purpose of the TDR is to measure the temperature of the water at various depths.  It is also used to verify that the depth where the camera comes to rest on the ocean bottom and is roughly equivalent to what the acoustic sounding reports at the site.  This is important because the camera generally doesn’t settle directly beneath the ship.  Its location is ultimately determined by the drift as it falls through the water column and current.  The actual TDR instrument is very small and is attached to the array near the bait bag.  After retrieving the array at each site, the TDR is removed from the array and brought inside to download the information.  To download, there is a small magnet that is used to tap the instrument (once) and then a stylus attached to the computer is used to read a flash of light emitted by an LED.  The magnet is then tapped four times on the instrument to clear the previous run’s data.  The data actually records the pressure exerted by the overlying water column in pounds per square inch (psi) which is then converted to a depth.

TDR instrument

Computer screen showing the data downloaded from the TDR.

The video from each day is uploaded to the computer system during the night shift.  The following day, Kevin Rademacher (chief scientist), views the videos and quickly annotates the “highlights”.  The following things are noted:  visual clarity (turbidity [cloudiness due to suspended materials], what the lighting is like [backlit], and possible focusing issues), substrate (what the bottom is made of), commercially viable fish, fish with specific management plans, presence of lionfish (an invasive species), and fish behavior.  Of the four cameras, the one with the best available image is noted for later viewing.

Computer data entry form for camera array image logs

Once back at the lab, the videos are more completely analyzed.  A typical 20-minute video will take anywhere from 30 minutes to three days to complete. This is highly dependent upon density and diversity of fish species seen; the greater the density and diversity, the longer or more viewing events it will take.  The experience of the reader is also an important factor. Depending upon the level of expertise, a review system is in place to “back read” or verify species identification. The resulting data is entered into a database which is then used to assign yearly data points for trend analysis. The final database is submitted to the various management councils.  From there, management or fisheries rebuilding plans are developed and hopefully, implemented.

Spotted moray eel viewed from the camera array.  He’s well camouflaged; can you find him?

Coney with a parasitic isopod attached below its eye.

Two Lionfish – an invasive species

Personal Log

Today, we are off the coast of St. Thomas and St. John in the U.S. Virgin Islands.  We traveled from the southern coast of  St. Croix, went around the western tip of the island and across the straight.  When I woke up I could see not only St. Thomas and St. John, but a host of smaller islands located off their coastline.

Map of the Virgin Islands. St. Croix and St. Thomas are separated by 35 miles of ocean. It took us about 3 hours to cross to our next set of sampling sites.

Around dinner time last night we had an interesting event happen on board.  They announced over the radio system that there was a leak in the water line and asked  us not to use the heads (toilets).  A while later, they announced no unnecessary use of water (showers, etc.); following that they shut off all water.  It didn’t take long for the repairs to occur, and soon the water was returned.  However, when I went to dinner, I discovered that the stateroom I’m sharing with Kelly Schill, the Ops Officer, had flooded.  Fortunately, the effects of the flooding were not nearly as bad as I had feared.  Only a small portion of the room had been affected.  The crew did a great job of rapidly assessing the problem and fixing it in a timely manner.  After this, I have absolutely no fear about any problems on board because I know the crew will react swiftly, maintain safety, and be professional all the while.

Last night was the first sunset I’ve seen since I’ve been on board.  Up until this point, it has been too hazy and cloudy.  The current haze is caused by dust/sand storms in the Sahara Desert blowing minute particles across the Atlantic Ocean.

St. Thomas sunset

Today has been a slow day with almost nary a fish caught.  We did catch one fish, but by default.  It was near the surface and hooked onto our bait.  We immediately reeled in the line and extracted it.  It was necessary to remove it because it would have skewed our data since it was caught at the surface and not near the reef.  This fish was a really exciting one for me to see, because it was a Shark Sucker (Echeneis naucrates).  These are the fish you may have seen that hang on to sharks waiting for tasty tidbits to float by.  They are always on the lookout for a free meal.

Shark sucker on measuring board

One of the most interesting aspects of the shark sucker is that they have a suction device called laminae on top of their heads that looks a little like a grooved Venetian blind system.  In order to attach to the shark (or other organism), they “open the blinds” and then close them creating a suction-like connection.

The “sucker” structure on the Shark Sucker. Don’t they look like Venetian blinds?

I got to not only see and feel this structure on the fish, but also let it attach itself to my arm!  It was the neatest feeling ever! The laminae are actually a modified dorsal spines; these spines are needed because of the roughness of shark’s skin. When the shark sucker detached itself from me, it left a red, slightly irritated mark on my arm that disappeared after a couple of hours.

Look, Ma, No Hands! Shark sucker attached to my arm.

Tomorrow we’ll be helping place a buoy in between St. Croix and St. Thomas.  It will be interesting to see the process and how the anchor is attached.

With all the weird and wonderful animals we’re retrieving, I can’t wait to see what another day of fishing brings.

Kathy Schroeder, May 12, 2010

NOAA Teacher at Sea
Kathy Schroeder
Aboard NOAA Ship Oscar Dyson
May 5 – May 18, 2010

Mission: Fisheries Surveys
Geographical Area: Eastern Bering Sea
Date: May 12, 2010

5/12 Mooring Buoy

Launching a mooring buoy

Launching a mooring buoy

Today we launched another type of buoy. It is called a Mooring Buoy. Its height is 5 meters above the surface (pictured on left) and 72 meters below the surface, which ends with a concrete dome that weighs 4110 (pictured on right). You can see the mooring being towed by the ship to get it into the right position. It has a barometer (measures atmospheric pressure), an anemometer (measures wind speed) and a thermometer on the top. There are sensors at different depths that measure salinity, chlorophyll, temperature, pressure, and nitrates.The information is transmitted to satellite Pacific Marine Environmental Lab (NOAA) that monitors the surface and subsurface of the Bering Sea. This piece of equipment costs $250,000. There are two other moorings already in this location. One measures ocean currents the other measures acoustic plankton. On one it has an underwater rain gauge. Can you figure out what that means? Headed to the Pribilof Islands today. On the way some crew saw sea ice. I’ll be looking! I love reading everyone’s comments. Keep them coming!