On board off the coast of North Carolina – about 35 miles east of Cape Fear, 40 miles south of Jacksonville, NC. (33º50’ N, 77º15’W)
Mission: South East Fisheries Independent Survey
Geographic Area of Cruise: Atlantic Ocean, SE US continental shelf ranging from Cape Hatteras, NC (35°30’ N, 75°19’W) to St. Lucie Inlet, FL (27°00’N, 75°59’W)
Here’s our location from the other day, courtesy of windy.com. And here is a good Gulf Stream explanation from our friends at NOAA:
Date: July 19, 2019
Science and Technology Log
Being at sea has got me thinking; about life at sea, the lives and careers of the men and women on board, and about the marine organisms around us. Pause there for a minute. Nature’s beauty and abundance on land is readily seen, so long as you travel to the right location and you’re patient. The ocean, however, hides its multitudes beneath the waves. I’ve found myself drawn to the ocean my whole life, and here on the cruise, I am drawn to staring at and contemplating the ocean and its life – the great hidden beneath. You know the stats: the earth is covered by ~70% water, the deep ocean has been explored less than outer space, the ocean is warming and turning more acidic, etc. I’m not saying that you and I don’t already know these things. I’m only saying that you feel them differently when you are in the ocean, when you are immersed for days in the seascape.
The goal is this cruise is to survey fish. (SEFIS = Southeast Fisheries Independent Survey). The science crew repeats a similar protocol each day of the cruise. It looks something like this:
Chief scientist, Zeb Schobernd, determines the site locations using NOAA sea floor maps.
The science team (broken into day and night shifts) baits six traps with menhaden fish bait, and starts the two GoPros that are attached to the traps.
The Pisces crew then deploys the traps, 1-6, at pre-determined locations (see step 1). They do this by sliding them off the back of the ship. Traps are attached to buoys for later pick up.
Wait for around 75 minutes.
Pisces Senior Survey Technician, Todd Walsh, along with crew members, Mike and Junior, drop the CTD [Conductivity, Temperature, Depth] probe. See picture below.
*Stay tuned for a video chronicling this process.
6. After ~75 min, NOAA Corps officers drive back to retrieve the traps, in the order they were dropped. (1-6)
7. Crew members Mike and Junior, along with scientists, collect the fish in the trap and sort them by species.
8. All fish are measured for weight and length.
9. Depending on the species, some fish contribute further information, most notably, their otoliths (to determine age) and a sample of reproductive organs to determine maturity.
10. Rinse and repeat, four times each day, for the length of the cruise.
I mostly work with the excellent morning crew.
The most excellent and experienced morning crew.Mike and Junior, running the CTD, and supporting their favorite NFL teams.
Here’s a view into yesterday’s fish count – more fish and more kinds of fish:
Here is a view off the back of the boat, called the stern, where the traps are dropped.
On Wednesday the GoPros on one of the fish traps collected footage of a friendly wandering tiger shark. Our camera technician, Mike Bollinger, using his stereo video technique, determined the size of the shark to be ~ 8.5 feet. I added the location’s CTD data to the picture. This is part of an upcoming video full of neat footage. See below.
Tiger Shark at 64.55 meters, footage from fish trap GoPro.
Personal Log:
Things continue to be exciting on board. My mission to film flying fish flying continues (local species unknown/not really sure; probably family: Exocoetidae). But not without some mild success! I managed to get some of ‘em flying off the port side near the bow. Man are they quick. And small. And the seas were rough. Yet I remain undeterred! Here’s a picture of me waiting and watching patiently, followed by a picture of an unlucky little flying fish who abandoned sea and was left stranded at ship. Poor little fella.
Waiting patiently for the flying fish to fly. And fly right where I was aiming and focused.
General Updates:
The seas have picked up quite a bit. Rising up to 5-6 feet. That may not seem terrifically high, but it sure does rock the ship. Good thing seas were flat at the start, allowing me to get used to life at sea.
I just saw some dolphins! Yippie! Pictures and video to come.
Though not legal, I’m dying to take a swim in these beautiful blue waters.
I don’t think I’ll ever get tired of watching the ocean. *short of being stranded at sea, I suppose. See “In the Heart of the Sea: The Tragedy of the Whaleship Essex” – a true story and great book that’s may have served as inspiration for Moby Dick. I loved the book, haven’t seen the movie. Or check out the lost at sea portions of the, hard-to-believe-it-actually-happened, “Unbroken” – great book, okay movie.
Neato Facts =
NOAA Ship Pisces won NOAA ship of the year in 2018. This is no doubt due to the most excellent crew, seen below. Congratulations!
We’ve caught a number of moray eels in the fish traps. They’re super squirmy and unfriendly. Turns out they also have pharyngeal mouth parts. Essentially a second mouth that shoots after their first one is opened. Check out this fascinating look into the morey eel’s jaw biomechanics.
Please let me know if you have any questions or comments.
NOAA Teacher at Sea Sue Zupko
Aboard NOAA Ship Henry B. Bigelow
September 7-19, 2014
Mission: Autumn Trawl Leg I Geographical Area of Cruise: Atlantic Ocean from Cape May, NJ to Cape Hatteras, NC Date: September 16, 2014
Weather Data from the Bridge Lat 36°54.2’N Lon 075°40.9’W
Present Weather CLR
Visibility 10 nm
Wind 300° 5-8 kts
Sea Level Pressure 1013.8
Sea Wave Height 1-2 ft
Temperature: Sea Water 24.3°C
Air 22.7°
Science and Technology Log
When on a field trip to Dauphin Island Sea Lab with my 5th grade students, I saw an exhibit about NOAA’s drifter program at the Estuarium. It seemed interesting to follow drifters on the ocean’s currents and learn more about our planet in the process. When I returned home from the trip, I visited the NOAA Adopt a Drifter site to see how my classes could get involved. The requirements include having an international partner with whom to share lessons and information. I was fortunate enough to find Sarah Hills of the TED Istanbul College through internet sites for teachers interested in collaborating. Her 6th grade English classes just began the school year and are studying maps. We both applied in late spring to the program as a team, explained our ideas for sharing information, and were accepted. Not only were we assigned one drifter, but two.
To create ownership for participants, NOAA sent stickers for us to sign and attach to the drifter. I was set to sail at the beginning of September so Mrs. Hills signed for her students. In addition to our friends’ stickers from Turkey, I attached stickers to the drifters signed by crew members, my students, friends, the science crew on board, and the NOAA officers on the Bigelow.
Stickers on Drifter
Sunday we deployed our drifters. They had come in a large cardboard box which had been sitting on the stern of the ship for almost two weeks. The directions were very simple. I just had to write down the identification number, rip off the magnet to turn it on, toss the drifter overboard, and write down the coordinates and time.
Drifters shipped to Bigelow and stowed in shipping box on fantail.
We were working close to the Gulf Stream so the captain had us enter the Gulf Stream so the drifters would catch that strong current and move out to sea. The water was pretty rough in the Gulf Stream, but, oh, the color of the water was a beautiful blue. When deploying (tossing it in the water) the drifter, I was not to remove any of the cardboard since the salt water would soften it and allow the drogue down below to drop down underwater (and it wouldn’t expand on the ship causing serious injury to us). The bosun (chief deckhand) suggested we push it off the fish board on the port stern quarter rather than tossing due to a lack of room.
Drifter…Ready…Set…
Go…
Drifters away!
Drifter in Gulf Stream
Drifter Deployment Team
The captain took pictures for me with my camera and the chief scientist ran the GoPro (a video camera). Must be an important operation when my two head bosses on the ship participate. We also had deckhands, Steve and James, our survey technician, Geoff, and Ensign Estela joining in on the fun.
After deploying the drifters, we watched them float in the Gulf Stream behind us. Where do you think they will end up? Track them and see where they are.
Both drifters came online when tossed in the water. However, one of them turned off shortly after it began its journey. Only time will tell if it turns back on.
I wrote down the necessary data on the form NOAA provided, took a picture of it, and sent it to the Drifter Team back at NOAA. They needed to assign them tracking numbers and put the link to the drifters on the web site.
The drifters last about 400 days. Click here to learn more.
Meet John Galbraith, our Chief Scientist
Chief scientist, John Galbraith, prepares to examine the nets
John is a mild-mannered man. He thinks through his answers and is very thorough to make sure his listener understands what he means. John has worked with NOAA for 23 years. I asked what he would be doing if he didn’t work with NOAA and he said, “Something outside with fish.” Can you guess what his hobbies are? There really is just one. Fishing. He loves fly fishing, trawling, casting, deep-sea fishing, you name it. If it involves fish, he loves it. As a matter of fact, he was so passionate about fish growing up that people always told him he would be a marine scientist. He grew up on Cape Cod in Massachusetts and loved to be outside, especially with fish.
John is passionate about the state of the environment. When I asked why he believes what we are doing with the Autumn Trawl Survey is important, he stated that it is imperative to monitor the health of our ocean through the survey. Data about fish populations (or most environmental science) must be collected over a long period of time, and using the same method, in order to make comparisons. Is what’s happening today different than what was happening 40 years ago with our fish populations? John said, “If we didn’t know what was there 20 years ago, for example, we wouldn’t know if the population of a fish species is more or less abundant.” This is the information we are gathering for scientists to evaluate.
What we are doing directly affects commercial and recreational fishing. He called this “pressure” since fisherman are changing the population of the fish they are catching. So, the surveys are looking to see what impact these pressures have on the fish. The data is used to help make or change rules for fisherman. So, if the population of a species is declining, and the larger fish are the ones needed for reproduction, for example, a rule might be installed saying that fish of a certain size cannot be kept. I found this in Canada when I went fishing this summer for Walleyed Pike. We could only keep four fish a day, and only one of those could be over 18 inches long. This helped preserve the ones who will keep reproducing so the species won’t disappear. Conversely, if there are a huge amount of a species of fish, the rules could change to allow more larger fish to be kept.
John loves his job because he loves seeing the diversity of fish. He spends 50% of his time on the boat to catch fish and the other 50% identifying fish in the lab. People are sent to him when they need a “fish expert”.
John said if he had to name the one tool he couldn’t live without it would be his fish database by Oracle. It is computer software to catalogue fish species. There is even a way to easily create web pages, which he really likes.
Now, related to this is a tool which already exists that he would love, but is very expensive. When we get certain little fish in the net, they are damaged (smushed) badly. He would like unlimited genetic testing of fish to verify the species. It would speed up identification of the fish.
John’s strength in getting the word out about fish is through his passion and willingness to teach others. Cruises such as the one I am on are the perfect opportunity to teach others. I predict a book or magazine article about fish or fish identification to be in his future so he can share his love of fish even more.
John’s advice to young people is to get stronger in math and science when it comes to school. When not at school, get outside and observe the world around you. So there is a tree on your hike. Do you know what kind it is? How tall will it grow? What lives on or in it? Look in the water. What type of fish are there? How is the type of water (pond, stream, lake) related to the fish that live there? Learn about your environment. Catch frogs and turtles and find out about them. John says all types of learning are important. He graduated from Roger Williams University in Rhode Island. Interestingly, several people on this ship graduated from there.
Personal Log
There are several types of doors on a ship. One is what you find in a home with a handle rather than a knob. Then, there are heavy doors with a wheel for certain bulkhead doors going outside. And, my favorite, the big handled doors between compartments inside. These all used to be wheels, and I found them very difficult to manage when on my last cruise.
Difficult for me to open wheel-style doors
New large levers.
Had to throw my weight into this door leading to the exercise room on the Pisces.
Did You Know?
Here is a mariner’s trick the captain was teaching the ensign on watch this morning. Remember these numbers. 6 & 10, 5 & 12. Did you know if you want to estimate a time of arrival (ETA) on a boat, you can calculate it quickly in your head? At 6 knots (kts) it takes 10 minutes to travel 1 nautical mile (nm). At 10 kts it takes 6 minutes to travel 1 nm. And at 5 kts it takes 12 minutes to travel 1 nm and at 12 kts it takes 5 minutes to travel 1 nm.
Question of the Day
How long would it take to travel 1 nm if steaming (traveling) at 20 kts?
Vocabulary
One of John’s favorite words: Congeners–These are things which appear incredibly similar; for fish it means the same genus, but different species. When I was trying to learn the different fish while sorting, I found the Croaker and the Spot to be similar. Both have a spot on their side, but the Spot’s spot is above his pectoral (side) fin and the Croaker’s is on its pectoral fin. The Pigfish, Butterfish, and Scup as well as the different Anchovies are difficult to identify when just learning.
Scup (Stenotomus chrysops)
Pigfish (Orthopristis chrysoptera)
Butterfish (Peprilus triacanthus)
Dusky Anchovy (lyolepis mitchilli)
Striped Anchovy (Anchoa hepsetus)
However, although these fish appear similar, all are in different genera and some in different families. An example of congeners that we have seen this trip would be the Marbled Puffer, Sphoeroides dorsalis, the Northern Puffer, Sphoeroides maculatus, and the Bandtail Puffer, Sphoeroides spengleri. All have the same genus, Sphoeroides – which implies that they are all very similar looking fishes. In fact, their body shapes are almost identical, but they each have different color patterns.
Something to Think About
If you spend all your time sitting at a computer, will you have more or less opportunity to understand about our environment? Can you see, hear, smell, feel, and taste it?
Challenge Yourself
Follow John’s advice and get outside more than you have been. Exploring the world around you is a great way to Sharpen the Saw, as we say at Weatherly using The Leader in Me program.
Mission: South Atlantic Marine Protected Area Survey
Geographical area of cruise: South Atlantic
Date: June 23, 2014
Weather:
Saturday: Sunny, some clouds, 27 degrees Celsius. 6.0 knot wind from the southwest. 1-2m seas.
Sunday: Cloudy with morning rain clearing to mostly sunny in the afternoon. 27 degrees Celsius. 13 knot wind from the west. 2-4m seas.
** Note: Upon request, note that if you click on any picture it should open full screen so you can the detail much better!
Science and Technology Log
Science Part I. The superhighway under the surface: sea currents
Until today, most everything including the weather and sea conditions were in our favor. On the surface it just looks like waves (ok well big waves) but underneath is a superhighway. On Sunday morning the currents throughout the water column were very strong. The result was the ROV and its power and fiber optic umbilical cord never reached a true vertical axis. Even with a 300lbs down-weight and five thrusters the ROV could not get to our desired depth of about 60m. The current grabbed its hold onto the thin cable and stretched it diagonally far under the ship – a dangerous situation with the propellers. The skill of ROV pilots Lance and Jason and the crew on the bridge navigated the challenging situation and we eventually retrieved the ROV back to the deck. I presume if I were back home on Goose Lake in Minnesota, I certainly would have ended up with the anchor rope wrapped around the props in a similar situation. So, where is the current coming from and how do we measure it aboard the Nancy Foster?
The Gulf Stream. Note the direction of the current and consider that on Sunday morning we were due east of North Carolina.
Answer: The Gulf Stream is an intense, warm ocean current in the western North Atlantic Ocean and it moves up the coast from Florida to North Carolina where it then heads east. You don’t have to be directly in the Gulf Stream to be affected by its force; eddies spin off of it and at times, water will return in the opposite direction on either side of it. Visit NOAA Education for more on ocean currents.
Answer: Aboard the Nancy Foster, we have a Teledyne ADCP – Acoustic Doppler Current Profiler. The ADCP measures direction, speed, and depths of the currents between the ship and the ocean floor. It’s not just one measurement of each; currents may be moving in different directions, at different depths, at different speeds. This can make a ROV dive challenging.
For example, at 4pm on Sunday near the Snowy Grouper MPA site off the coast of North Carolina, from 0-70 meters in depth the current was coming from the north and at about 2 knots. At 70 meters to the sea floor bottom it was coming from the south at over 2 knots. Almost completely opposite.
Hydrophone
Another indication of the strong currents today was the force against the hydrophone. Hydrophones detect acoustic signals in the ocean. We are using a hydrophone mounted on the side of the Nancy Foster to communicate the location of the ROV to the ship. The hydrophone has to be lowered and secured to the ship before each dive. It ended up in my blog today because the current was so strong, three of us could not swing and pull the hydrophone to a vertical position in the water column. It was a good indicator the currents were much stronger than the past few days.
Science Part II. Discoveries of Dives in the Deep
Snowy Grouper – one primary species we are on the hunt for this mission
Snowy Grouper are one of the species requiring management due to low and threatened stock levels within the federal 200-mile limit of the Atlantic off the coasts of North Carolina, South Carolina, Georgia and east Florida to Key West. The MPAs help conserve and manage these species. We were excited to have a few visit the camera lens the past two days.
Pair of Snowy Groupers photographed during one of our dives on Friday, June 20. Sizes are approximately 30-50cm (12-20″).Photo credit: NOAA/UNCW. Mohawk ROV June 2014.
Snowy Grouper photographed during one of our dives on Friday, June 20. Size is approximately 40-50cm (16-20″). Photo credit: NOAA/UNCW. Mohawk ROV June 2014.
Snowy Grouper and a Roughtongue Bass photographed during one of our dives on Friday, June 20. Photo credit: NOAA/UNCW. Mohawk ROV June 2014.
Scorpianfish (scorpaenidea)
Scorpionfish (Scorpaenidea) photographed during one of dives on Saturday, June 21. Photo credit: NOAA/UNCW. Mohawk ROV June 2014.
Eel
Eel photographed during one of our dives on Saturday, June 21. Saw many of these peeking out of their homes in crevices. We were lucky to capture this one in its entirety. Photo credit: NOAA/UNCW. Mohawk ROV June 2014.
Invertebrates – (with much thanks to my education from Stephanie Farrington)
Leiodermatium, Nicella, feather duster crinoids, and a Red Porgy in the far background. Photo credit: NOAA/UNCW. Mohawk ROV June 2014.
Science Part III. Rugosity-
Rugosity is sea- bottom roughness. Probably one of the terms and skills I will remember most about this experience. In oceanography, rugosity is determined in addition to the other characteristics I am more accustomed to: slope, composition, and the cover type (plants, animals, invertebrates.) It was a little challenging for me to incorporate this into my observations the first few days so thought I would share two of the stark differences. This compliments my strong knowledge and passion for teaching earth science with Earth Adventure; I cannot wait to use this content in future Earth Balloon & Earth Walk Programs!
Rugosity Comparison. Low rugosity on the left; high rugosity on the right. The low has a flat plain where as the high has rocks, deep crevasses, slopes, and texture. Snowy Grouper desire high rugosity. Photo credit: NOAA/UNCW. Mohawk ROV June 2014.
Science Part III. Day Shapes
When a ship has restricted ability to move, the ship displays vertically (up to down) from the mast a black ball, diamond, and black ball. This informs other ships and vessels in the area not to approach the Nancy Foster as we can’t move; the ROV is in the water. While radio communication is an option, this is a marine standard that signals others to stay away. If we were deploying the ROV at night, a series of lights communicate the same message. On Sunday morning, we observed three recreational fishing boats probably a 1.5 kilometers from the ship. It seemed one was moving towards us likely interested in what was happening aboard the giant Nancy Foster.
Day shapes displayed on the Nancy Foster ship mast; black ball, diamond, and black ball. The NF has restricted ability to move; the ROV is in the water.
Career highlight:
Lance Horn and Jason White are the two ROV pilots on board from the University of North Carolina Wilmington.
ROV pilots Lance Horn and Jason White. On the left, Lance surveys the ocean ‘shall we launch the ROV or not?’ – or perhaps he is just thinking deep thoughts. On right, Lance and Jason preparing the cable prior to dive.
John & Jason White at the ROV pilot control center.
Personal Log:
A week without television. While I brought movies on my iPad and there is a lounge equipped with more than nine leather recliners, a widescreen, and amazing surround sound, I haven’t yet sat down long enough to watch anything. I spend 12 hours a day being a shadow to the researches trying to absorb as much as I can and lending a hand in anything that can help the mission. Most of my evenings have been consumed by researching species we saw during the dives using taxonomy keys and well, just asking a lot of questions. I go through hundreds of digital pictures from the ROV and try to make sense of the many pages of notes I make as the researchers discuss species, habitats, and characteristics during the dives. While I am using a trust book version as well as the multiple poster versions scattered on the walls in the lab, here is a great online key.
Sunday evening, crew members of the Nancy Foster invited me to join them in a game of Mexican Train – a game using Dominos. Thanks Tim for including me! I am going to have to purchase this for cabin weekends up north in Minnesota (when the mosquitoes get so large they will carry you away and we can no longer go out in the evenings).
When the Acoustic Doppler Current Profiler wasn’t working, we just called on King Neptune and his kite to help us gauge the wind speed, direction and the currents. Wait, I thought he carried a scepter?
Tim Olsen, Chief Engineer – 11 years on the Nancy Foster and 30 years as Chief Engineer.
Espresso! I really was worried about the coffee when coming aboard the Nancy Foster for 12+ days. What would I do without my Caribou Coffee or Starbucks? Chief Steward Lito and Second Cook Bob to the rescue with an espresso machine in the mess. John has been very happy – and very awake.
I made it a little more progress reading The Big Thirst by Charles Fishman.
“In 2009, we spent $21 billion on bottled water, more on Poland Spring, FIJI Water, Evian, Aquafina, and Dasani than we spent buying iPhones, iPods, and all the music and apps we load on them.” (p337)
Glossary to Enhance Your Mind
Each of my logs is going to have a list of new vocabulary to enhance your knowledge. I am not going to post the definitions; that might be a future student assignment.
NOAA’s Coral Reef Watch has a great site of definitions at
NOAA Teacher at Sea Dave Grant Aboard NOAA Ship Ronald H. Brown February 15 – March 5, 2012
Mission: Western Boundary Time Series Geographical Area: Sub-Tropical Atlantic, off the Coast of the Bahamas Date: March 3, 2012
Weather Data from the Bridge
Position:30 deg 37 min North Latitude & 79 deg 29 min West Longitude
Windspeed: 30 knots
Wind Direction: North
Air Temperature: 14.1 deg C / 57.4 deg F
Water Temperature: 25.6 deg C / 78.4 deg F
Atm Pressure: 1007.2 mb
Water Depth:740 meters / 2428 feet
Cloud Cover: 85%
Cloud Type: Cumulonimbus and Stratus
Science/Technology Log:
Entering the Gulf Stream and Straits of Florida
“There is in the world no other such majestic flow of waters.
Its current is more rapid than the Mississippi or the Amazon.
Its waters, as far out from the Gulf as the Carolina coasts, are of an indigo blue.
They are so distinctly marked that their line of junction with the common sea-water
may be traced by the eye.”
Matthew Maury – The Physical Geography of the Sea
While our cruise could hardly be called leisurely, most sampling has been spread out between sites, sometimes involving day-long periods on station while the CTD and moorings are recovered from great depths (5,000 meters). However, Chief Scientist Dr. Baringer regularly reminds us that west of the Bahamas in the Gulf Stream transect, our stations are in much shallower water (≤800 meters) and close together (The Florida Straits are only about 50 miles wide), so we should anticipate increased activity on deck and in the lab. In addition to the hydrology measurements, we will deploy a specialized net to sample those minute creatures that live at the surface film of the water – the neuston.
The Neuston net is deployed for a 10-minute tow.
Now that we have crossed the Bahama Banks and are on-station, the routine is, as expected, very condensed, and there is little time to rest. What I did not anticipate was the great flow of the Gulf Stream and the challenge to the crew to keep the Brown on our East-West transect line as the current forces us north. Additionally, as Wordsworth wrote, “with ships the sea was sprinkled far and wide” and we had to avoid many other craft, including another research ship sampling in the same area.
Ben Franklin is famous for having produced the first chart of this great Western Boundary Current, but naval officer Matthew Maury – America’s Scientist of the Sea – and author of what is recognized as the first oceanography text, best described it. Remarkably, in The Physical Geography of the Sea, first published in 1855, he anticipates the significance of this major climate study project and summarizes it in a short and often-quoted paragraph:
“There is a river in the ocean. In the severest of droughts it never fails,
and in the mightiest floods it never overflows.
Its banks and its bottom are of cold water, while its current is of warm.
The Gulf of Mexico is its fountain, and its mouth is the Arctic seas.
It is the Gulf Stream.”
Gulf Stream water
CTD data from the Straits of Florida 1. Note that temperature (Red) decreases steadily with depth from about 26-degrees C at the surface, to less than 10-degrees C at 700 meters. (Most of the ocean’s waters are cool where not warmed by sunlight). 2. Dissolved Oxygen (Green) varies considerably from a maximum at the surface, with a sharp decline at about 100 meters, and a more gradual decline to about 700 meters. (Phytoplankton in surface water produce excess oxygen through photosynthesis during daylight hours. At night and below about 100 meters, respiration predominates and organisms reduce the level of dissolved oxygen.) 3. Salinity (Blue) is related to atmospheric processes (Precipitation and Evaporation) and also varies according to depth, being saltiest at about 150 meters.
At Midnight, just within sight of the beam of the Jupiter Inlet Lighthouse (And to the relief of the home-sick sailors on board – “Finally – after more than two weeks, we are within the range of cell phone towers!”) we began our studies of the Straits of Florida and the Gulf Stream. Nine stations in rapid order – standing-by for a CTD cast, and then turning into the current to set the neuston net for a ten-minute tow.
The purpose of the net is to sample creatures that live on or visit the interface between air and water, so the mouth of the net is only half submerged. Neuston comes from the Greek for swimming and in warm waters a variety of invertebrates and even some young mesopelagic fishes rise within a few centimeters of the surface at night to filter phytoplankton and bacteria, and feed upon other zooplankton and even drowned terrestrial insects that have been blown out to sea.
On the upper side of this water/atmosphere interface, a smaller variety of floating invertebrates, notably Physalia and Velella (Portuguese man-of-war and By-the-wind-sailor) use gas-filled buoyancy chambers or surface tension to ride the winds and currents. This much smaller group of seafarers is further classified by oceanographers as Pleuston.
Prior to this cruise, my experience with such a sampling device was limited – Years ago, spending miserable nights sailing in choppy seas off of Sandy Hook, NJ searching for fishes eggs and larva rising to the surface after dark; and later, much more enjoyable times studying water striders – peculiar insects that spend their lives utilizing surface tension to skate along the surface of Cape Cod ponds.
Our CTD and net casts are complicated by rising winds and chop, but some great samples were retrieved. Once the net is recovered, we rinse it down with the seawater hose, collect everything from the bottle at the codend, rinse off and separate the great mass of weed (Sargassum) and pickle the neuston in bottles of alcohol for analysis back at the lab.
Midnight shift: Recovering the net by moonlight.
Midnight shift: Recovering the net by moonlight.
Since much of the zooplankton community rises closer to the surface at night where phytoplankton is more concentrated and the chances of being preyed upon are slimmer, there are some noticeable differences in the samples taken then and during daylight hours. Unavoidably, both samples contain great quantities of Sargassum but the weed-colored carapaces of the different crustaceans are a clue to which specimens are from the Sargassum community and which are not.
Gulfweed Shrimp – Latreutes
We hit the jackpot early; snaring a variety of invertebrates and fishes, including the extraordinarily well-camouflaged Sargassum fish – a piscatorial phenomenon I’ve hoped to see ever since I was a kid reading William Beebe’s classic The Arcturus Adventure. What a tenuous existence for such a vulnerable and weak swimmer, hugging the Sargassum as it is dashed about in the waves. Even with its weed-like disguise and ability to blend in with the plants, it must lead a challenging life.
A unique member of the otherwise bottom-dwelling frogfishes, the Histriohistrio has smooth skin, and spends its life hitch-hiking along in the gulf-weed forest. Like other members of the family Antennariidae, it is an ambush predator, luring other creatures to their doom by angling with its fleshy fins.
The Sargassum fish (Histrio)
Needlefish and Sargassum fish
Another highlight for me is the water striders we found in several samples. These “true bugs” (Hemiptera) are remarkable for several reasons. Most varieties of these “pond-skaters” (Or Jesus Bugs if you are from Texas) are found on calm freshwater lakes and streams, but a few members of this family (Gerridae) are the only true marine insects – representing a tentative Arthropod reinvasion of the sea after their splendid foray onto land hundreds of millions of years ago.
Two great finds: Sygnathus pelagicus– A Sargassum pipefish – a cousin of the sea horse. Halobates – the water strider. An example of the Pleuston community.
Using surface tension to their advantage, they “skate” along by flicking their middle and hind legs, and can even “communicate” with each other by vibrating the surface of the water with the hair-like setae on their feet. On lakes their prey is other insects like mosquito larvae, confined to the surface. How they manage to find food and communicate at the surface of the raging sea is a mystery, but whatever the means, they are adept at it, and we recovered them in half of the samples.
The ocean’s insect: The remarkable water stride
The scientists who provided the net are generally more interested in ichthyoplankton to monitor fish eggs and larvae to predict population trends, and monitor impacts like oil spills; so this is why samples are preserved to return to the lab in Miami.
Before packing up things after our marathon sampling spree I was able to examine our catch and observed a few things:
1. I am the “High-Hook” on the cruise – catching far more fishes (albeit tiny ones) than the rest of the crew with their fishing poles. (Needlefish, sargassum fish, pipe fish, filefish and several larval species)
2. Depending on the time of day the samples were taken, there is a marked difference in the quantity and composition of organisms that have separated from the Sargassum and settled in the sample jars – (Noticeably more at night than during daylight hours).
3. There appears to be a greater variety of sea grasses present (Turtle grass, etc.) on the eastern (Bahamas side) of the Straits. We observed one seabean – drift seeds and fruits (or disseminules) from terrestrial plants.
4. Plastic bits are present in all samples – particularly plastic ties (Table 1.)
Settled organisms in sample jars.
Sargassum fauna: Portunid crab – with eggs on her belly. (Portunus was a Roman god – Protector of harbors and gates,
who supposedly also invented navigation)
Belly view of a Caridean shrimp
A tiny fish egg ready to hatch!
A larval fish begins its perilous journey in the Gulf Stream.
Site/Local time
Notable Contents*
Biomass
Site
Depth
8 Day 17:48
Weed, Grasses(3 spp)
3.0 mm
79˚12’
485 m
7 Day 16:10
Grasses(4 spp)
2.0 mm
79˚17’
616 m
6 Day 14:30
Grasses(2 spp) Fish eggs and larva
Trace
79˚22’
708 m
5 Day 12:45
Water striders, Grass (1 spp)
Trace
79˚30’
759 m
4 Day 10:13
Crustacean larva, shrimp (large),
7.0 mm
79˚36’
646 m
3 Dawn 07:53
Crustacean larva, shrimp (large), water striders
Trace
79˚41’
543 m
2 Night 05:10
Crustacean larva, shrimp (small), Pipefish, water striders
*Plastic bits and Sargassum weed and its endemic epibionts are present in all samples.
Table 1. Contents in sample jars.
There is a marked difference in the quantity and composition of organisms collected at night (Left).
There is a marked difference in the quantity and composition of organisms collected during the day (Right).
With sampling completed we steer north to ride the Gulf Stream towards the Brown’s home-port, and turn away from the bright lights of Florida …
“Where the spent lights quiver and gleam;
Where the salt weed sways in the stream;
Where the sea-beasts rang’d all around
Feed in the ooze of their pasture ground:”
Matthew Arnold
“Red sky at morning…sailor take warning!”
Homeward bound:
A storm battering the Midwest will impede our progress back north to Charleston and threatens to bring us the only foul weather of the cruise. Note the location of the cold front over the Florida Straits.
“Now the great winds shoreward blow; Now the salt tides seaward flow; Now the wild white horses play, Champ and chafe and toss the spray.”
Matthew Arnold
As the sailors say: “The sheep are grazing.” A gale is brewing and kicking up whitecaps as we sail north to Charleston.
NOAA Teacher at Sea Dave Grant Aboard NOAA Ship Ronald H. Brown February 15 – March 5, 2012
Mission: Western Boundary Time Series Geographical Area: Sub-Tropical Atlantic, off the Coast of the Bahamas Date: March 2, 2012
Weather Data from the Bridge
Position: 26 degrees 19 minutes North Latitude & 79 degrees 55 minutes West Longitude
Windspeed: 14 knots
Wind Direction: South
Air Temperature: 25.4 deg C / 77.7 deg F
Water Temperature: 26.1 deg C / 79 deg F
Atm Pressure: 1014.7 mb
Water Depth: 242 m / 794 feet
Cloud Cover: none
Cloud Type: NA
“The moment one gives close attention to anything, even a blade of grass,
it becomes a mysterious, awesome, indescribably magnificent world in itself.”
Henry Miller
My evenings looking through the microscope are a short course in invertebrate zoology. Every drop of water filtered through the plankton net reveals new and mystifying creatures. Perhaps 90% of marine invertebrates, like newly hatched mollusks and crustaceans, spend part of their life in a drifting stage – meroplankton; as opposed to holoplankton – organisms that are planktonic throughout their life cycle.
MOLLUSK LARVAE
Bivalve
Univalve
The lucky individuals that escape being eaten, and are near a suitable substrate at the right moment, settle out into a sedentary life far from their place of origin. For the long distance travelers swept up in the Gulf Stream, the most fortunate waifs of the sea that survive long enough might make it all the way to Bermuda. The only hope for the remainder is to attach to a piece of flotsam or jetsam, or an unnatural and unlikely refuge like the electronic picket fence of moorings the Ron Brown is servicing east of the Bahamas.
“The gaudy, babbling, and remorseful day, Is crept into the bosom of the sea.” Shakespeare
A league and a half* of cable, sensors and a ton of anchor chain are wrestled on deck during a day-long operation in the tropical heat. (*A mariner’s league equals three nautical miles or 3041 fathoms [18,246 feet])
It is easy to be humbled by the immensity of the sea and the scope of the mooring project while observing miles of cable and buoys stretched towards the horizon, about to be set in place with a ton of anchor chain gingerly swung off the stern for its half-hour trip to the bosom of the sea.
Thanks to the hard labor and alert eyes of our British and French (“And Irish”) colleagues retrieving and deploying the attached temperature and salinity sensors, I am regularly directed to investigate “something crawling out of the gear” or to photograph bite marks from deep sea denizens on very expensive, but sturdy equipment.
A retrieved sensor with bite marks.
To my surprise, other than teeth marks, very little evidence of marine life is present on the miles of lines and devices strung deeper than about 200 meters. This may be due in part to the materials of which they are constructed and protective coatings to prevent bio-fouling, but sunlight or more precisely, the attenuation of it as one goes deeper, is probably the most important factor.
Fireworm (Drawings and images by Dave Grant – NOAA Ron Brown)
Handle with care! Close-up of worm spines
The first discovery I was directed to was a striking red bristle worm wiggling out of the crevice in a buoy. It appears to be one of the reef-dwelling Amphinomids – the aptly-named fireworms that SCUBA divers in the Caribbean avoid because of their venomous spines; so I was cautious when handling it. This proved to be the deepest-dwelling organism we found, along with some minute growths of stony and soft corals.
“Five o’clock shadow” on a buoy – A year’s growth of fouling organisms – only an inch tall.
On shallower buoys and equipment, there are sparse growths of brown and blue-green algae, small numbers of goose barnacles, tiny coiled limey tubes of Serpulid worms like the Spirobis found on the floating gulfweed, some non-descript bivalves (Anomia?) covered with other fouling growth, skeleton shrimp creeping like inch-worms, and of course the ubiquitous Bryozoans. Searching through this depauperate community not as challenging as the plankton samples, but not surprising since our distance from land, reefs or upwelling areas – and especially clear water and lack of seabirds and fishes; are all indicators that this is a nutrient-deficient, less productive part of the ocean.
Bio-fouling – “on the half-shell.” Skeleton shrimp (Caprellidae)
The Ron Brown is the largest workhorse in the NOAA fleet and its labs and decks are intentionally cleared of equipment between cruises so that visiting scientists can bring aboard their own gear that is best suited to their specific project needs. NOAA’s physical oceanographers from Miami arrived with a truckload of crates holding Niskin water sampling bottles for the CTD and their chemistry equipment for DO (Dissolved Oxygen) and salinity measurements; and in a large shipping container (“Ship-tainer”) from England, the British and French (“and Irish”) scientists transported their own remote sensing gear, buoys, and (quite literally) tons of massive chain and cables to anchor their moorings. (I am surprised to learn from the “Brits” that the heavy chain is shipped all the way from England because it is increasingly hard to acquire. )
In the lab: Scores of sensors serviced and ready for deployment
This is how most science is facilitated on the Brown and it requires many months of planning and pre-positioning of materials. I am lucky and can travel light – and with little advanced preparation. I am using simple methods to obtain plankton samples and images via a small portable microscope, digital camera and plankton net which I can cram into my backpack for any trips that involve large bodies of water. The little Swift* scope has three lens (4x, 10x, 40x) with a 10x ocular, and I get great resolution at 40x, and can get decent resolution to 100x. Using tips from Dave Bulloch (Handbook for the Marine Naturalist) I am able to push that somewhat with a simple Nikon Coolpix* point-and-shoot camera – but lose some of the sharpness with digital zoom. As you might suspect, the ship’s movement and engine vibration can be a challenge when peering through the scope, but is satisfactory for some preliminary identification. (*These are not commercial endorsements, but I can be bought if either company is willing to fund my next cruise!)
PHYTOPLANKTON
Centric diatom – Coscinodiscus
Dinoflagellates – Different Ceratium species
ZOOPLANKTON
A Plankton précis
Collecting specimens would be much more difficult without the cooperation of the Brown’s crew and visiting scientists, and their assistance is always reliable and appreciated. The least effective method of collection has been by filtering the deep, cold bottom water brought up in the Niskin bottles. As mentioned earlier, no live specimens were recovered; only fragments of diatom and Silicoflagellate skeletons surviving the slow drift to the bottom, which I have been able to identify through deep sea core images posted at the Consortium for Ocean Leadership website.
Needless to say, the most indiscriminate method of collection and the most material collected is through the large neuston net. The greatest biomass observed on the trip is the millions of tons of Sargassum weed, which covers the surface in great slacks around us that are even visible in satellite images.
Although the continuous flow of ocean water pumped into the wet lab and through my plankton net is effective and the most convenient collection method, the most surprising finds are from the saltwater intake screens that the engineer directed me to. This includes bizarre crystal-clear, inch-long, and paper-thin Phylosoma – larvae of tropical lobsters – that I initially mistook for pieces of plastic.
Inch-long Phylosoma larvae on a glass slide. (One of the tropical lobsters.)
“All the ingenious men, and all the scientific men, and all the fanciful men in the world …
…could never invent anything so curious and so ridiculous, as a lobster.”
Charles Kingsley -The Water-Babies
Plankton communities are noticeably different between the Gulf Stream, inshore, and offshore in the pelagic waters east of the Bahamas. Near the coast, either the shallower Bahama Banks or the neritic waters over the continental shelf closer to Charleston, the plankton is larger, more familiar to me and less challenging to sort, including: copepods, mollusk larvae and diatoms. Steaming over the shelf waters at night, the ship’s wake is often phosphorescent, and dinoflagellates, including the “night-light” Noctiluca are common in those samples.
Dinoflagellate – Noctiluca
The waters east of the Bahamas along the transect line are notable for their zooplankton, including great numbers and varieties of Foraminifera, and some striking amphipod shrimp. Compared to cooler waters I am familiar with, subtropical waters here have over a dozen species of Forams, and some astonishingly colorful shrimp that come up nightly from deeper water.
It’s not all work and no play on the Ron Brown, and there are entertaining moments like decorating foam cups with school logos to send down with the CTD to document the extreme pressure at the bottom. Brought back to class, these graphically illustrate to younger students the challenges of deep sea research.
Foam cup: Before-and-after a trip to 5,000 meters
Navigating by Dead-reckoning
On calm days while we are being held on-station by the Brown’s powerful thrusters, I can measure current speeds using Sargassum clumps as Dutchman’s logs as they drift by. Long before modern navigation devices, sailors would have to use dead-reckoning techniques to estimate their progress. One method used a float attached to a measured spool of knotted line (A log-line), trailing behind the moving vessel. The navigator counted the number of knots that passed through his hands as the line played out behind the ship to estimate the vessel’s speed (in knots). Since nothing is to be tossed off the Brown, I rely on a simpler method by following the progress of the Sargassum as it drifts by stem-to-stern while we are stationary at our sampling site. Since I know the length of the Brown at the waterline (~100-meters), I can estimate current speed by observing drifting Sargassum.
Watching sargassum, I wonder if a swimmer could keep pace with the currents in these waters. When in college
my brothers and would strive to cover a 100-meter race by swimming it in under a minute. Here is the data from east of the Bahamas. See if you can determine the current speed there and if a good swimmer could keep pace.
ESTIMATING CURRENT SPEED
Data on currents:
Average of three measurements of Sargassum drifting the length of the Ron Brown = 245 seconds.
Length of the Ron Brown – 100-meters.
1. How many meters per second is the current east of the Bahamas?
2. As a swimmer in college – with my best time in the 100-meters freestyle of one minute – could I have kept up with the Ron Brown… or been swept away towards the Bahamas?
Other navigational exercises I try to include determining Latitude and Longitude. Latitude is easy as long as you can shoot the sun at midday or find the altitude of Polaris in the night sky; and sailors have done that for centuries. The ship’s navigator will get out the sextant for this, or, since the width of one’s fist is about 10-degrees of sky, I can estimate the height of both of these navigational beacons by counting the number of fists between the star and the horizon.
ESTIMATING LATITUDE
Data:
Night observation (Shooting the North Star) – Number of Fists from the Northern horizon to Polaris = 3
Day observation (Shooting the Sun) – Number of Fists from the Southern horizon to the Sun = 5.5
If the width of a fist is equal to about 10-degrees of horizon, our estimate of Latitude using Polaris is 30-degrees (3 x 10).
Not too bad an estimate on a rocking ship at night, compared to our actual location (See Data from the Bridge at the top.).
Shooting the Sun at its Zenith at 12:30 that day gives us its altitude as 55-degrees – which seems too high unless we consider the earth’s tilt (23.5-degrees). So if we deduct that (55 – 23.5) we get 31.5, which is closer to our actual position. And if we consult an Almanac, we know that the sun is still about six degrees below the Equator on its seasonal trip North; so by deducting that (31.5 – 6) we end up with an estimate of 25.5-degrees. This is an even better estimate of our Latitude.
Here is the dreaded word problem:
By shooting the Sun, our best estimate of Latitude is 25.5 degrees (25 degrees/30 minutes)
The actual Latitude of the ship using GPS is 26-degrees/19 minutes.
If there are 60 minutes to a degree of Latitude – each of those minutes representing a Nautical Mile – how many Nautical Miles off course does our estimate place us on the featureless sea?
**************************
Longitude is much harder to determine if you don’t have an accurate timepiece to compare local time with universal time (The time at Greenwich, England), and an accurate ship’s chronometer wasn’t in use until the mid-1700’s.
To understand the challenge of designing a precise timepiece that reliably will function at sea, I used two crucial clock mechanisms: a pendulum and a spring. Finding a spring was easy, since “Doc” had a scale at Sick Bay. For the pendulum I fashioned a small weight swinging on a string)
Using the scale to observe the ship’s motion.
Standing on the scale and swinging the pendulum even in calm weather quickly demonstrated three things:
First: I have developed my sea legs, and no longer notice the regular motion of the ship. Second: Even when the sea feels calm, the scale’s spring mechanism swings back and forth under my weight; adding and deducting 20 pounds to my real weight and reflecting the ship’s rocking that I no longer notice. Three: On rough days, even if I can hold still, the ship’s heaving, pitching and rolling alters my pendulum’s reliable swing – its movements reflecting the ship’s indicator in the lab. Experimenting helps me appreciate clock-maker John Harrison, and his massive, 65-pound No. 1 Ship’s Chronometer he presented to the Royal Navy in 1728.
Ship movement as recorded by the computer
Doc: Always on duty – Sick Bay on the Ron Brown
Besides having very well-provisioned Sick Bays, NOAA ships have experienced and very competent medical officers. Our “Doc” received his training at Yale, and served as a medic during the Gulf War.
Especially alert to anyone who exhibits even the mildest symptoms of sea-sickness, Christian is available 24-hours for emergencies – and in spite of the crew constantly wrestling with heavy equipment on a rocking deck, we’ve only experienced a few minor bumps and bruises. He has regular office hours every day, and is constantly on the move around the ship when not on duty there.
Besides keeping us healthy, he helps keep the ship humming by testing the drinking water supply (The Brown desalinates seawater when underway, but takes on local water while in port); surveys all departments for safety issues; and with the Captain, has the final word if-or-when a cruise is to be terminated if there is a medical emergency.
Since a stormpounding the Midwest will head out to sea and cross our path when we head north to Charleston, he is reminding everyone that remedies for sea sickness are always available at his office door, and thanks to NASA and the space program, if the motion sickness pills don’t work, he has available stronger medicine. So far we have been blessed with relatively calm weather and a resilient crew.
The warm (Red) Gulf Stream waters viewed from a satellite image.
Contact: The edge of the Gulf Stream – Matthew Maury’s River in the Ocean
Birdwatching on the Ron Brown
For the time being I take advantage of the calm seas to scrutinize what’s under the microscope, and when on break, look for seabirds. East of the Bahamas, as anticipated after consulting ornithologist Poul Jespersen’s map of Atlantic bird sightings, I only spotted two birds over a two-week stretch at sea (storm petrels). This is very much in contrast to the dozens of species and hundreds of seabirds spotted in the rich waters of the Humboldt Current off of Chile , where I joined the Brown in 2008.
(http://ux.brookdalecc.edu/staff/Web%2012-2-04/seabirds/Brown%20terns%202/Terns%20%20fixed/SEPacific.html)
Passing through Bahamian waters was no more rewarding, but now that we are west and in the Florida Straits there are several species of gulls during the day, and at night more storm petrels startled by the ship’s lights. One windy night a large disoriented bird (Shearwater?) suddenly fluttered out of the dark and brushed my head before bumping a deck light and careening back out into the darkness. Throughout the day a cohort of terns has taken up watch on the forward mast of the Brown and noisily, they juggle for the best positions at the bow – resting until the ship flushes a school of flying fishes, and then swooping down across the water trying and snatch one in mid-air. Like most fishermen, they are successful only about 10% of the time.
Caspian tern “on station” at the jack mast.
Royal tern “on station” at the jack mast.
*************************************
Despite the dreary forecast from the Captain, Wes and I are enthusiastic about all we have done on the cruise and formulated a list of why NOAA’s Teacher At Sea program is so rewarding.
Top Ten Reasons:
Why be a Teacher At Sea?
10. Fun and excitement exploring the oceans!
9. Meeting dedicated and diligent scientists and crew from around the world!
8. Bragging rights in the Teachers’ Room – and endless anecdotes!
7. Cool NOAA t-shirts, pins and hats from the Ship’s Store!
6. Great meals, three times a day…and FREE laundry!
5. Amazing sunsets, sunrises and star-watches!
4. Reporting on BIG science to students…and in real-time!
3. Outstanding and relevant knowledge brought back to students and colleagues!
2. First-hand experience that relates to your students’ career objectives!
1. Rewarding hours in the lab and field…remembering why you love science and sharing it with students!
NOAA Teacher at Sea Wes Struble Aboard NOAA Ship Ronald H. Brown February 15 – March 5, 2012
Mission: Western Boundary Time Series Geographical Area: Sub-Tropical Atlantic, off the Coast of the Bahamas Date: February 27, 2012
Weather Data from the Bridge
Position: 26 degrees 31 minutes North Latitude & 76 degrees 48 minutes West Longitude / 9 miles east of the Bahamas
Windspeed: 8 knots
Wind Direction: East by Southeast
Air Temperature: 24.8 deg C / 76.5 deg F
Water Temperature: 24.2 deg C / 75.5 deg F
Atm Pressure: 1025 mb
Water Depth: 3830 meters / 12,770 feet
Cloud Cover: Approximately 60%
Cloud Type: Some altostratus and cumulostratus
Science/Technology Log:
The temperature has become quite warm and it has been a delight to walk around the deck in the sunshine in a t-shirt and shorts (the current weather back home is between 10 and 20 deg F and snowing). As you can see from the photo below the weather continues to be clear with some fair weather cumulus clouds and a light breeze.
A view of the wide western Atlantic off the Ron Brown's bow from the weather deck several days after leaving the port of Charleston, SC
The Ron Brown's wake trailing off into the west as we head toward our first CTD station
NOAA research scientist, Dr. Molly Baringer, Chief Scientist during the cruise, catches up on some computer work and reading in the shade of the bridge on the "lifeguard chair" on the "steel beach" (the weather deck) of the NOAA research vessel Ronald H Brown
A drifter buoy arrives prepackaged and ready for deployment
Removing the plastic packaging and recording the coordinates and serial number of the drifter buoy before deployment
A drifter buoy ready for deployment by Dr. Aurelie Duchez
Dr. Aurelie Duchez tosses the drifter over the stern of the Ron Brown. This cruise is a continuation of a long period of study (over 30 years) of the Gulf Stream and the Western Boundary currents in and around the region of Florida and the Bahamas. This region is of particular interest because of the impact these currents have on the weather and climate patterns of the northeastern North America and Northern Europe. The Gulf Stream current helps transport large amounts of heat energy derived from the equatorial Atlantic to the northern latitudes of America and Europe. An image of the Gulf Stream current from space - NASA photo. The Gulf Stream is the orange colored current that passes on the east coast of Florida and flows north along the eastern seaboard of the US
This phenomenon helps to moderate the climates of those areas by producing milder temperatures than would normally occur at these latitudes. Changes in the characteristics of these currents could potentially have a profound affect on the climates of these regions and it would be of particular interest to understand in detail the nature and interaction of these mobile bodies of water. To study these currents a combination of techniques have been employed. We should all be familiar with the concept of induction – the process of producing a current in a conductor by moving it through an electromagnetic field. This was one of the more important discoveries of Michael Faraday and is one for which we should be very grateful since most of our modern world depends upon the application of this scientific discovery.
Michael Faraday - the great British Scientist
As an example think of what modern life would be like without electric motors or generators. Well, it just so happens there exist old communications cables on the seafloor under these very currents between south Florida and the Bahamas. These cables are affected by a combination of the earth’s magnetic field and the motion of the seawater (a solution composed primarily of dissolved ions, charged particles, of Na+ and Cl–). This combination of charges, motion, and the earth’s magnetic field causes a weak electrical current to be induced in the cable – a current which researchers have been able to measure.
A schematic showings the induction of an electric current in the underwater cable by motion of the sea water current (NOAA Image)
The electric current in the cable can be related mathematically to the strength of the ocean currents flowing over them. In addition to the data produced by the cable, the NOAA scientists are also deploying moored buoys below the surface that measure the characteristics of the seawater (temperature, density, etc) and use an Acoustic Doppler array to measure the relative motion of the current.
ADCP (Acoustic Doppler Current Profiler) and two other types of buoys - image from Grand Valley State University
An ADCP (Acoustic Doppler Current Profiler) buoy - Image from SAIC
A buoy deployment operation on the Ron Brown. Notice the large orange spherical ADCP buoys in the right foreground on the deck of the ship
These two data acquisition systems (in addition to the drifter buoys and CTD sampling) provide the data used to analyze the dynamics of the currents. As more data is collected and analyzed the nature and impact of these currents is slowly unraveled. Consider visiting the following website for a more detailed explanation:
NOAA Teacher at Sea
Jessie Soder
Aboard NOAA Ship Delaware II
August 8 – 19, 2011
Mission: Atlantic Surfclam and Ocean Quahog Survey Geographical Area of Cruise: Northern Atlantic Date:Wednesday, August 17, 2011
Weather Data
Time: 12:00
Location: 41°19.095 N, 71°03.261
Air Temp: 22°C (°F)
Water Temp: 21°C (°F)
Wind Direction: South
Wind Speed: 7 knots
Sea Wave height: 0
Sea Swell: 0
Science and Technology Log
Gulf of Maine: Including Georges Bank
So far, we have spent this entire trip on Georges Bank. This famous geographical location off the east coast of the United States is something that I had only heard about before this trip. After several tows over the past week I have been able to see a variety of materials brought up from the ocean floor of Georges Bank. I have seen loads of clams, empty shells, sand, mud and clay, and smooth polished rocks. We have even pulled up a few boulders that must have weighed a couple of hundred pounds. It was the smooth polished rocks that caught my attention. How would a rock from the bottom of the ocean become smooth and rounded? It probably meant that Georges Bank must not have always been the bottom of the ocean.
During the Wisconsin Glaciation the ice reached its maximum around 18,000 years ago. The Laurentide ice sheet paused in the area of Georges Bank and Cape Cod and left behind a recessional moraine that created these landforms. This ice also had several meltwater streams flowing from it and these streams were responsible for the polishing the rocks and cutting some of the canyons found on the seafloor today. The Northeast Channel off the northeast side of Georges Bank was the principle water gap for most of the meltwater.
Smooth Polished Rocks From the Ocean Floor
Georges Bank is a huge oval-shaped shoal bigger than Massachusetts that starts about 62 miles offshore. It is part of the continental shelf and its shallowest areas are approximately 13 feet deep and its deepest areas 200 feet. In fact, thousands of years ago Georges Bank used to be above water and an extension of Cape Cod. About 14,000 years ago the sea rose enough to isolate this area and it was home to many prehistoric animals such as mastodons and giant sloths. Today, traces of these animals are sometimes found in fishing nets! These animals died out about 11,500 years ago when the sea level rose further and submerged the area.
Georges Bank is a very productive fishing area in the North Atlantic. (The Grand Banks is more productive, but not as geographically accessible as Georges Banks.) Why is Georges Bank a prime feeding and breeding area for cod, haddock, herring, flounder, lobsters, and clams? It has to do with ocean currents. Cold, nutrient rich water from the Labrador Current sweeps over the bank and mixes with warmer water from the Gulf Stream on the eastern edges of Georges Bank. The mingling of these two currents, plus sunlight, creates an ideal environment for phytoplankton, which is food for the zooplankton. In fact, the phytoplankton grow three times faster here than on any other continental shelf. All of this plankton feeds the ecosystem of fish, birds, marine mammals, and shellfish that flourish on Georges Banks.
Personal Log
Yesterday we left Georges Bank for stations off the coast of Rhode Island. After dark, I stepped out on the back deck and Jimmy pointed out the lights of Nantucket and Martha’s Vineyard. We were in sight of land for the first time in a week. It wasn’t long before people had their cell phones out and were making calls.
A few times during this trip I have thought about sailors in the past and how they would leave for months, and even years, at a time and not have contact with their families and loved ones until they returned. I have had email contact this entire time, yet I am really excited to go home to see those that I miss. I can hardly imagine what it would be like to be gone for a year with no contact at all.
Throughout this trip I have been getting to know others on this cruise. I have learned that several of them have families and young children at home. Many of them are at sea for many weeks, or months, a year. After being on this cruise, I have gained a lot of respect for people who choose to work on the ocean for a living. It takes a certain type of person who can work hard, maintain a positive attitude, and live away from their home and loved ones for extended periods of time. It has been an honor to work with these people.
