NOAA Teacher at Sea
Tara Treichel
Onboard NOAA Ship Nancy Foster April 15-27, 2008
Mission: Lionfish Survey Geographical Area: Atlantic Ocean, off the coast of North Carolina Date: April 25, 2008
The diver support boat NF-4 waits for the dive team to surface.
Weather Data from the Bridge
Visibility: 10 n.m.
Wind: 2 knots
Waves: 1 foot
Ocean swells: 2-3 feet
Sea surface temperature: 23.4
Air temperature: 21.5
Science and Technology Log
Today the morning dive at Lobster Rocks went to 125 feet. The report was that it was an excellent dive, and the video showed this to be true. The visibility was excellent and the habitat looked rich. Among the Amberjacks, Grouper, Blue Angelfish, and Hogfish, were tons of Lionfish! They were everywhere, lurking around every ledge and rock. They look like princes of their domain, regal in their showy capes of red and white, brandishing lances to keep out intruders. Neither aggressive nor fearful, as they have few if any predators, they hover in place, guarding their territory from other lionfish.
NOAA Teacher at Sea, Tara Treichel, has just taken length and fin ray measurements from this large lionfish, and has removed gonads and a gill sample for lab analysis.
The morning divers brought a small collection of creatures back for further study, including a sample of bryozoans (a form of attached invertebrates that looks a lot like algae), a large spiny lobster (carapace at least 5 inches in diameter), a handful of fish for the cryptic fish survey, and about a dozen Lionfish. I helped Wilson take basic measurements from the Lionfish, and dissected them to remove gonads and gill samples for DNA analysis. The fish ranged in size from 150 to 380 mm, from mouth to end of tail. Next, dorsal and anal fin rays are counted, to help determine species classification (lionfish are of Indo-Pacific origin, and are classed in two subspecies based on number of fin rays). On the fish sampled, dorsal fin rays varied between 10 and 11.5, but anal fin rays consistently numbered 7.5. After I had removed the gill section and gonads, I gave the fish to Brian, who opened up their stomachs to take a cursory look at what the fish had been eating. In one, he found a small spiral shell about the size of a shirt button. In another, the stomach was bulging full, and contained four small fish, whole but partially digested and terribly stinky. All in a day’s work of a scientist! After this initial information was collected, the fish were labeled in zip-lock bags and frozen for later study.
The stomach of this small Lionfish contained four partially digested whole fish.
Personal log
Today I had the fortune—and the misfortune—of getting out in one of the small boats. I say fortune because the conditions were ideal: calm seas and sunny blue skies. It was a great day to be out on the water, and I expressed an interest in going for a swim. We were responsible for shuttling the safety diver to assist the dive team, and transporting the dive team back to the NANCY FOSTER. The misfortune occurred toward the end of the dive, as the safety diver was trying to reboard the boat. To make it easier for him to enter the boat, the skipper removed the side door of the craft, a routine task. Under normal circumstances, the bilge pumps purge any water that splashes into the boat, but on this day, for reasons unknown the bilge was already full of water, and the water that surged into the open door space quickly filled the stern of the boat. We tried to replace the door, but the water was spilling in too quickly, and the boat slowly overturned. So, I got my wish to swim faster than I’d expected! Fortunately, as I mentioned, it was a fine day for a swim. Minutes later, two rescue boats were deployed from the NANCY FOSTER, and shortly after we picked up the dive team and were safely onboard the mother ship again. The ship had quite a challenge getting the overturned boat back onboard and into its cradle, but with skilled use of the crane, the boat was recovered in little over an hour. It was the sort of adventure I had least expected when going out to sea. I was happy that no one got hurt, and impressed with the response of the NANCY FOSTER crew.
NOAA Teacher at Sea
Scott Donnelly
Onboard NOAA Ship McArthur II April 20-27, 2008
Mission: Assembly of Science Team and Movement of Science Gear/Equipment Geographical Area: Coos Bay to Astoria, Oregon Date: April 24, 2008
Water collection from Niskin bottles
Weather Data from the Bridge
Sunrise: 0620 Sunset: 2010
Wind: 10 kts
Seas: 2 ft
Light rain showers possible
Science and Technology Log
As forecasted for Wednesday night the turbulent seas have calmed and the howling winds coming from all directions have subsided. On occasion a large wave smashes into the ship broadside. But, for the most part, it seems like the storm has moved onto land. Sampling operations restarted around 2000 (8pm) last night. This morning from 0100 to 0500 is my sixth 4-hour shift. Today nearshore and offshore CTD and biological sampling continues at different longitudes 124O29’W to 125O15’W but constant latitude 43O07’N. This is called a longitudinal sampling survey. The latitude and longitude coordinates align with the westward flow of water from Coos Bay estuary in Coos Bay, OR. Along these coordinates CTD deployment will reach depths as shallow as 50m (164ft) to as deep as ~2,800m (~9,200ft)! Round-trip CTD measurements will take more time due to progressively greater depths with increasing distance from the OR coast. On my morning shift we collected samples at two stations. At the second station 30 miles from the coast the CTD was deployed to a depth of 600m (1,970 feet).
Monitoring CTD data
During Thursday’s afternoon shift (my seventh 4-hour shift) the CTD was lowered to a depth of ~2,700m (~8,860 feet) located 50 miles from the coast. At this distance out at sea, the coastal landmass drops below the horizon due to the curvature of the earth and the up and down wave action. The round-trip CTD deployment and retrieval to such great depths take about two hours to complete. The dissolved oxygen (DO) probe measurements indicate a secondary DO layer in deep water. So how are the continuous data measured by the CTD organized? What are the trends in data? In science graphs are used to organize numerical data into a visual representation that’s easier to analyze and to see trends. Below is a representative drawing of how CTD and wet lab data are organized and presented in the same visual space. Note the generous use of colors to focus the eyes and show the differences in data trends.
What are some trends that can be inferred from the graph above? First, with increasing depth, seawater becomes colder (maroon line) until below a certain depth the water temperature is more or less at a constant or uniformly cold temperature (compared to the surface). Second, the amount of dissolved oxygen (DO) in seawater (green line) is greatest near the surface and decreases, at first slightly then abruptly, with increasing depth below the surface. Third, salinity (red line), which is directly related to conductivity, increases with increasing depth. Furthermore, in general seawater pH (blue line) becomes more acidic (and conversely, less basic) with increasing depth. Last, marine photosynthetic activity as measured by chlorophyll a in phytoplankton (purple line) is limited to the ocean’s upper water column called the photic zone. Below this depth, sunlight’s penetrating ability in seawater is significantly reduced below levels for photosynthesis to be carried out efficiently and without a great expense of energy.
The consistently low (acidic) pH measurements of deep water collected by the Niskin bottles and analyzed on deck in the wet lab are a concern since calcium carbonate (CaCO3) solubility is pH dependent. On this cruise the pH measurements between surface and deep waters show a difference of two orders of magnitude or a 100 fold difference. Roughly, pH = 8 for surface water versus pH = 6 for deep water offshore. This difference in two pH units (ΔpH = 2) is considerable as it indicates that the deep water samples are 100 times more acidic than the surface water. pH is a logarithmic base ten relationship, i.e. pH = -log [acid] where the brackets indicate the concentration of acid present in a seawater sample. A mathematical difference in two pH units (ΔpH = 2) translates into a 100 fold (10ΔpH = 102) difference in acid concentration. Refer to the Saturday, April 19 log for a discussion concerning the importance of CaCO3 in the marine environment and the net acidification of seawater.
Personal Log
After the morning shift but before a hearty breakfast of eggs, hashed browns, sausage, bacon, and juice, I hung out on the ship’s port side to watch the sunrise, a memorable mix of red, yellow, and orange painting the sky. It was one of the best sunrises I remember and that’s saying a lot since I live in southern Arizona, where the sunrises and sunsets are the stuff of legends. With the low pressure system having moved over land, the sea was calm and the temperature considerably warmer with no clouds positioned between it and the ocean. Perhaps surprisingly, I haven’t sighted a whale or a whale spout, even in shallower, more nutrient-rich coastal waters. It’s not that I haven’t looked as each day I’ve visited the flying bridge (observation deck) above the operations bridge enjoying the immensity of the vast Pacific.
A flock of albatross have begun following the ship I suspect in hopes of getting a fish meal, mistakenly thinking that the McARTHUR II is a trawler. I saw trash, which I couldn’t identify without binoculars, floating on the surface. Sadly, even the vast, deep oceans and its inhabitants are not immune from humanity’s detritus. The history of humanity and its civilizations are intimately linked to the world’s oceans. This will not change. Humanity’s future as well is linked to its maritime heritage. The oceans have fed us well and have unselfishly given its resources without complaint. Perhaps it’s time we return the compliment and lessen our impact.
NOAA Teacher at Sea
Tara Treichel
Onboard NOAA Ship Nancy Foster April 15-27, 2008
Mission: Lionfish Survey Geographical Area: Atlantic Ocean, off the coast of North Carolina Date: April 24, 2008
Weather Data from the Bridge
Visibility: 10 n.m.
Wind: 7 knots
Waves: 2-3 feet
Ocean swells: 3-5 feet
Sea surface temperature: 24.5
Air temperature: 23
NOAA Divers at the rail of the ship just before a dive
Science and Technology Log
Today the NANCY FOSTER deployed four dive teams, two each at two survey sites. This is a tricky maneuver, requiring the coordination of many people. Preparations included an hour-long briefing of the plan and review of safety information, in which divers were reminded, among other things, to stay close to their buddies since an “out of air” emergency could spell the end of future diving opportunities with NOAA. On the deck, the chaos was well managed. With extensive use of hand-held 2-way radios, communication was maintained between the bridge (control station of the NANCY FOSTER), the two small boats, and the deck support: the two small boats were launched with the aid of the crane, and the mother ship was jockeyed into position alongside the dive site target buoys that had been dropped earlier. When the position was just right, the call was made, “Divers to the rail,” and the four divers, weighed down by double layers of wetsuit, twin tanks, dive computers, and mesh bags holding notepads and pencils, were lead to the edge of the boat. One by one, they stepped off the boat and disappeared beneath the surface, leaving a trail of bubbles to mark their descent.
The divers will visit sites that were selected years ago when the lionfish study first began. The sites were chosen using benthic maps of the ocean floor to help identify favorable fish habitat. Today’s dives were at “WOO6” and “Big Fish”, in 130 and 150 feet respectively. These depths are beyond my PADI Open Water limit of 90 feet, and require mixed Nitrox gas in order to extend the underwater dive time. Use of mixed gas at these depths qualifies this as “technical diving” and involves an increased risk to the divers, so the NOAA lab has contracted with NURF (National Underwater Research Foundation) to provide technical dive support. Divers have strict bottom time limits and must make several safety stops on their ascent; in addition, a Hyperlite recompression tank stands at ready for any nitrogen sickness emergencies (“the bends”). During the dives, the researchers do a variety of tasks. All of the researchers take general habitat notes, and record the presence of marine debris. Paula and Brian are surveying the large, “conspicuous” fish, including lionfish, by estimating the population size of each species along a given transect length. Paula also will collect a temperature logger that she placed at the site 1 year ago, which has recorded temperature data every half hour. Roldan and Christine are surveying “cryptic” fish communities (prey species that are very small or that hide within the habitat). Roldan lays out a one-meter square PVC quadrate and chemically stuns and collects the fish, which he then captures in a Ziploc bag for later study. Wilson is studying the algal community, but finds that there is very little to collect this early in the season. He also spears a number of lionfish for later study, which he bags carefully to avoid being stung by the venomous spines. Finally, Thor and Doug alternate between video camera duties, documenting the underwater habitat.
NOAA Ship NANCY FOSTER as seen from the divers’ support boat
Personal log
First impressions, and notes on the boat: The ship is due into port at 1700, and it is right on time. After the events of the past week, this is a pleasant surprise. I am struck by the size of the ship. It is massive and bulky, with a flared steel bow that towers over me as I watch from the pier. Quite unlike the nautical parallel parking that I learned as a teenager growing up on a northern Wisconsin lake, this ship is equipped with side thrusters that allow it to maneuver its bulk with some amount of precision. Immediately, I can see that understanding momentum is a key factor in handling this boat: the ship is anything but “quick on its feet” when a change in direction is needed, and lack of planning for this fact could be disastrous. But today is not the day for a demonstration of this lesson. After 20 minutes of adjustments, the two-inch deck lines are thrown out from the ship, and it is securely tied to rest for the night.
A flurry of activity ensues. There is excitement in the air, like the charge before an electrical storm. The outgoing crew is anxious to be on home turf again, after weeks away at sea and in foreign ports, and the new team of scientists is equally anxious to get underway and begin their mission. The wind adds to the fervor, whipping my hair across my face and sending the Stars-n-Stripes cracking over the stern of the ship. The gang plank is lowered into position by the lower deck crane and a cargo net is secured below. For the next 10 minutes, there is a steady flow of bodies and boxes, as mail is shipped onboard and supplies from the previous mission are offloaded. A deck crane is used to hoist crates of heavy equipment on board, including dozens of SCUBA tanks.
Loading the scientists’ equipment onto the FOSTER using the ship’s deck crane
The NANCY FOSTER is an oceanographic research vessel of the NOAA fleet. One hundred eighty feet on deck and built of steel, she is made for ocean navigation and equipped for scientific research. She was built in 1986 by the Navy as a torpedo tester, and is considered very seaworthy. Throughout the year, she is used for a variety of scientific research missions, each research team outfitting the boat with its own specific technical equipment. Two onboard labs are designated for this purpose: a dry lab, housing numerous computer stations and data processing equipment kept dry (and frigid) with continuous air conditioning. All told, including mine, there are 16 computers in this room. One wall holds 7 flat-screen monitors, one of which displays a live video stream of the stern decks of the ship, where at the present moment a hopeful engineer is dragging a fishing line through the rolling blue waves. Adjacent to the dry lab is the wet lab, mostly an empty room that quickly fills with scientists’ tools of the trade: bins, underwater cameras, measuring devices, dissecting equipment and specimen preservation chemicals, and bags upon bags of SCUBA gear. In the wet lab, I get my first glimpse of our quarry, and the purpose of the mission: numerous copies of fish identification books adorn the tables, and the walls are full of color posters depicting creatures of the deep—echinoderms, manatees, Caribbean reef fishes.
Looking around the ship, one can’t help but notice the references to danger. All around are reminders of things that could go wrong (and undoubtedly have). Most noticeable is the large red motorized rescue craft hanging from the mid deck crane. Next to it is a green painted stamp indicating an emergency meeting or “muster” area. To the left of this is a coiled canvas fire hose, with the stamp “No Smoking” printed above (elsewhere, crew are instructed to smoke aft of the rear crane, preferably “away from the gasoline cans” and where the SCUBA oxygen bottles are being filled). Across the deck from the fire hose is a closet holding 10 Immersion Suits, 5 medium and 5 large, as well as 15 life jackets. Around the corner are three oversized barrels containing full immersion survival gear, including 25 person life rafts. Down the railing from the barrels and placed all throughout the ship in various conspicuous places are the timeless classic orange life-rings printed with the ship’s name in black blocky script. Inside the boat, there are more reminders: emergency procedures, the ship’s interior plan depicting the location of every rescue device and exit onboard, and numerous posters outlining CPR in simple steps and photographs. I would not want to have an emergency on board this ship, but if the unthinkable happened, I am confident that this ship and crew are well prepared.
I am led through watertight doors and down a narrow flight of stairs into the belly of the beast, on the first floor of the ship. My berth is in Stateroom 17, which sleeps four, in bunks containing mattresses that give a whole new definition to the size “single”. I choose a top bunk, which gives me a little more head room amidst the crisscross of pipes overhead. I am instructed to unload everything into the closets and cabinets that line the walls, since everything that’s not strapped down or contained in a box will be subject to repositioning by the motion of the ship. And motion there is! As soon as we get out of the harbor and away from shore, the 4-5 foot waves set the boat into an irregular pattern of constant swaying from side to side as well as front to back, like a rocking horse on a swivel. I won’t elaborate on the effects of this motion on my body and mental state, since seasickness has been well described elsewhere. Suffice to say that the benefit of the tiny pink pills can’t be overstated, and I am now feeling fine. A few more notes on ship travel: Why was I surprised to see the stream of water from the faucet sway back and forth? (okay, if you want to be technical, this is a matter of perspective: in actuality, the water stayed straight and it was the sink/boat that moved relative to the vertical line of water, but the effect was still startling). Another amusing note: the dry lab was full of wheeled cushy office chairs, on a painted steel floor. Remedy? Each chair’s legs were bungeed to the nearest bench support. Depending on the bungee, this left a range of motion of each weighted chair of a foot or two. Picture it: a room full of scientists at work on their computers, all sliding in unison into their neighbor’s workspace for a moment, only to be yanked back to center, and then rolling away to the other side…
NOAA Teacher at Sea
Scott Donnelly
Onboard NOAA Ship McArthur II April 20-27, 2008
Mission: Assembly of Science Team and Movement of Science Gear/Equipment Geographical Area: Coos Bay to Astoria, Oregon Date: April 23, 2008
Weather Data from the Bridge
Sunrise: 0620 Sunset: 2010
Wind: 10 kts, 30 kt gusts
Seas: 4-7 ft
Light rain showers
Low resolution radar image of the storm system that postponed cruise operations
Science and Technology Log
My fourth (0100 to 0500, 1am to 5am) and fifth (1300 to 1700, 1pm to 5pm) 4-hour shifts are postponed due to the continued inclement weather. Seas are turbulent (combined seas 16 feet) and the winds blow non-stop (30 knots with gusts near 40 knots) from all directions it seems. Standing on deck both port and starboard, the howling wind throws sharp sea spray darts at my unprotected face. For a seasoned mariner these conditions are probably routine, if not prosaic. But for a newbie like me, with a little more than 48 hours of sea time experience, they are impressive and awe-inspiring, especially so given that I’m watching
it all from in the midst of the storm and not from the relative safety of the shore as I’ve done at times in San Diego. I climb the stairs to the ship’s bridge to watch and videotape this grand spectacle. The captain is calm and seems unimpressed with the temperamental, chaotic happenings outside. As I make my way to the bridge’s front viewing window he says to me, “Crummy weather isn’t it.” Without thinking, I nod my head in agreement. Also, a gale warning remains in effect until 1400 (2pm) this afternoon. A gale force wind has sustained surface speeds greater than 34 knots (39mph).
CTD deployment and biological sampling with the nets are postponed until the weather subsides and is more conducive to on deck activity. If the weather cooperates and the night forecast is accurate, the plan is to resume water sampling with the CTD and collection of marine organisms around 2000 (8pm) tonight. In the meantime the CTD has been securely fastened to the fantail deck. The coordinates for today’s postponed longitudinal sampling (constant latitude, changes in longitude) are 43O07’N, 124O29’W to 125O15’W.
With the postponement in work activity in today’s log I’ll discuss a number of topics. In the following paragraphs I’ll discuss some of the nautical terms used in marine weather conditions as found in today’s forecast (see beginning of log, top) and what a low pressure system is. In yesterday’s log I described what a bongo net is and how it works. Today I’ll talk about the marine organisms that a bongo net collects and also describe the other three zooplankton nets used on this cruise- the Manta, ring, and HAB nets. Let’s begin with nautical terms used in marine weather forecasts.
Winds are identified with respect to the direction from which the wind originates. Surface water currents on the other hand are identified with respect to the direction they are flowing. So for example, today’s morning forecasted southeast (SE) winds originate from the southeast and blow toward the northwest (NW) since in general winds travel in a straight line path when not disrupted. Conversely, today’s forecasted morning southwest (SW) swells are traveling in the southwest direction. Marine wind and ship speeds are measured in terms of knots (kts). One knot (one nautical mile per hour, nm/hr) equals 1.15 statuary (or land) miles per hour, mph. Today’s forecasted morning wind speed of 25kts then equals 29mph, with morning gusts (G) forecasted at 30kts or 35mph and subsiding by mid-afternoon.
A change in winds from the SE to the E and then NW as forecasted from AM to PM indicates that the storm system is moving in a northeast direction onto land.
What is a swell? A swell is a mature wind wave of a given wavelength (distance between successive wave crests, i.e. the highest point of a wave) that forms orderly undulations seen on the ocean surface. Swells are described with respect to their height and period. Wave height is self-explanatory. What about wave period? Notice in the weather forecast that a wave period is defined in terms of time (typically seconds). Let’s use a hypothetical situation to explain a wave period. Suppose you are standing on deck, looking out across the vast sea, and a wave passes across your line of sight. Seven seconds later another wave crosses your line of sight, which remains unchanged. Seven seconds later another wave passes; your line of sight is still unchanged. The wave period then is the time elapsed for successive waves to pass a fixed point. In general, the longer the period, the calmer the sea.
Dense krill “soup”
Since my arrival in Oregon on Friday, April 18 a low pressure system has been positioned off the Oregon coast bringing clouds and precipitation. Today’s stormy seas are a result of a low pressure system. The winds and clouds in a low pressure system rotate in a counter-clockwise direction when viewed from satellites above. So if the winds blow from the southeast (SE) and are sustained, this indicates that the northern region of the low pressure system is south of the observer. In yesterday’s log I wrote briefly about how a bongo net is deployed and its function. So what marine organisms are collected in a bongo net? On this cruise at the depths the bongo net is deployed, it’s mostly a thumb-sized, shrimplike crustacean called krill. Krill are an important and central component of the oceans’ food chains and webs. In the northeastern Pacific the predominant species of krill is Euphausia pacifica. They are prolific consumers of microscopic marine organisms too small to see with the naked eye. But they too are consumed in enormous quantities by seabirds, squid, fishes, whales, and more recently, humans.
As seen in the upper right photo Euphausia pacifica krill have red “spots” along the entire length of their transparent, tubular bodies. These “spots” are photophores (light emitting organs) that emit blue light when a krill is agitated. During the 0100 to 0500 shift when it’s relatively dark on deck, one can see the blue emitted light from individual krill (but not all simultaneously) when the detached cod end of the bongo net is shaken. The emission of light from living organisms is called bioluminescence. Remember the scene in the 2003 Academy Award winning, computer-animated family film Finding Nemo when Nemo’s iconic clownfish father, Marlin, and his absent-minded blue tang friend Dory descend into the pitch-black deep water to find the scuba mask dropped when Marlin’s colorful, curious son Nemo was captured by the scuba diver. Dory is mesmerized by a glowing light that suddenly appears. Both eventually escape becoming a meal for a deep water fish that uses bioluminescence to attract and then eat unsuspecting prey.
Euphausia pacifica
A sub-category of bioluminescence is chemiluminescence, which refers to the emission of visible light on account of a chemical reaction. In the krill’s photophores is a creatively named molecule called luciferin, which combines with its complementary enzyme called luciferase, to emit blue light. Of all the known bioluminescence in the natural, biological world, an overwhelming majority is found in marine organisms, especially those found in deep water where light from the sun does not penetrate.
In yesterday’s log I wrote briefly about the function of a bongo net in collecting marine organisms (zooplankton) in a horizontal water column below the ocean’s surface. How are the nearly weightless, free-floating zooplankton found at the ocean’s surface and a few inches below collected? In the following paragraphs I’ll answer this question and also describe the nets used to collect marine organisms in a water column vertical (or perpendicular) to the surface.
Manta net in action
A Manta net (also called a Neuston net) collects zooplankton at and a few inches below the ocean’s surface. Like a bongo net it too collects marine organisms found in a horizontal column of seawater. This requires the ship to be moving forward. Since a Manta net collects marine organisms at the surface and a few inches below, weights are not attached to the Manta net’s metal rectangular frame which also serves as its mouth. Floats are permanently attached to the right and left of the net’s mouth. A rotary flowmeter is suspended in the net’s mouth so the water volume can be determined. Like a bongo net the biomass density (number of organisms per volume water) then can be estimated. For our cruise the Manta net was deployed starboard once every shift for a total of ten minutes for each cast.
Scott Donnelly (green helmet) retrieving a Manta net
Two other nets used on this cruise are a ring net and a HAB (Harmful Algal Bloom) net, both of which are used to collect samples in a column of water vertical or perpendicular to the ocean surface. Consequently, the ship must not be moving and the net weighted for vertical sampling of a water column to occur since the nets themselves are not dense enough to sink. Deployment and retrieval of both nets are simple enough. Basically, the net is attached to a winch cable and a weight, is slowly lowered into the water to the desired depth and kept there for the desired time before it’s slowly lifted upward through the water, brought alongside the ship and suspended, washed with seawater, lifted onto the ship’s deck, and the collected sample removed from the cod end. The organisms collected represent those found in the vertical column of water through which the net ascended. On account of their small, compact size and weight, both the ring and HAB nets can be managed with one person, thereby freeing the other to take care of other sampling tasks.
Manta net skimming the surface for zooplankton
What is Harmful Algal Bloom (HAB)? HAB is caused by the elevated levels of toxins produced by certain marine algae that proliferate when seawater conditions are favorable for increased rates of reproduction. The microscopic algae are consumed by the ocean’s voracious eaters called phytoplankton. One of the toxins released by these certain marine algae is domoic acid, which accumulates in the phytoplankton that consume the algae. The phytoplankton are eaten by shellfish and fish such as anchovies and sardines. Domoic acid is poisonous to the shellfish and other fish thereby increasing mortality rates. If the toxin levels are elevated, massive die-offs occur, beaches are closed, and the sale and human consumption of shellfish, etc. are prohibited. The biological, social, and economic impacts are painful.
Personal Log
In spite of the ship’s constant pitching and rolling in these unsettled, stormy seas, I slept well Tuesday night, taking two hour catnaps, waking for ten minutes or so, and then falling back to sleep for another two hours or so before waking after midnight to get ready for the 1am shift. About mid-morning I made a visit to the bridge where ship operations are carried out. According to ship’s radar the low pressure system and local squalls causing the inclement weather shows signs of letting up.
HAB net deployment as seen from above
Almost three full days on the ship and I have shown no indications or symptoms of sea sickness in spite of the constantly changing seas. According to the NOAA crew I’ve earned my sea legs and it’s not likely that I’ll get sea sick. So much for all the tablets of Dramamine I brought. I took some memorable video from the bridge (both inside and outside) of the ship’s bow rising and falling between waves, some of them smashing violently into the McARTHUR’s bow on both the port (left) and starboard (right) sides, sending seawater spray up to the bridge window and all about the bow’s deck. I felt like a true mariner. Still no sightings of whales, orca, or the Black Pearl of Pirates of the Caribbean film fame.
NOAA Teacher at Sea
Scott Donnelly
Onboard NOAA Ship McArthur II April 20-27, 2008
Mission: Assembly of Science Team and Movement of Science Gear/Equipment Geographical Area: Coos Bay to Astoria, Oregon Date: April 22, 2008
Weather Data from the Bridge
Sunrise: 0620 Sunset: 2010
Wind: 10 kts, 25 kts gusts
Seas: 4-7 ft
Rain showers possible
Open Niskin bottles on CTD platform
Science and Technology Log
What’s the significance of the NH Line (Newport Hydrographic, 44O39’N)? Water and biotic data acquisition at the NH Line began over 40 years ago. The NH Line then is significant on account of the long-term historical sample collection and data sets that it provides. Consequently, temporal (time) comparisons involving water and biotic data can be made over decades as opposed to shorter lengths of time such as years or months. It’s my understanding that nearshore and offshore sampling along the Oregon Continental Shelf (OCS) always includes the NH Line. My second 4-hour shift began at 0100 and ended shortly after 0500. Regardless of time of day each shift sets up and collects water samples from each of the twelve Niskin bottles on the CTD rosette. Typically, three water samples are collected at a particular depth. How does remote sub-surface water sampling work? When the CTD is deployed from the ship’s fantail, initially the top and bottom lids on all twelve Niskin bottles are open as shown in the photo below.
The CTD is lowered into the water and once the desired depth is reached the requisite number of Niskin bottles are closed electronically from the ship by whoever is in the control room. For my shift it’s team leader Ali Helms. After that is done, the CTD then is lowered or raised to another depth where another “firing” takes place and more water samples at a different depth are collected. When sampling is complete, the CTD is raised to the surface and onto the ship where it is secured to the fantail deck. The water in each Niskin bottle is collected and taken to the ship’s wet lab where each water sample collected at a particular depth is analyzed for other water quality parameters not measured by the CTD.
YSI datalogger
Other water parameters measured on this cruise in the wet lab include: total dissolved solids (TDS), pH, and turbidity (how transparent, or conversely cloudy, is the water). A YSI 6600 datalogger interfaced with a multi-sensor water quality probe (sonde) is used to measure the aforementioned water parameters. See photos below. The CTD and Niskin bottles then are hosed down with freshwater and reset for the next sampling site. After the CTD is reset for the next sampling site, then it’s time to collect biotic samples from the surface and at different depths. Biological sampling always follows a CTD cast. On this cruise biological sampling is carried out on the ship’s starboard side just fore of the fantail. Collection of marine invertebrate (boneless) organisms uses nets that vary in size, shape, density of net mesh (number of threads per inch), and volume of detachable sample collection container (called a cod end). Sampling nets are conical in shape and typically are made from Dacron or nylon threads that are woven in a consistent, interlocking pattern. Each specifically designed net is attached to a wire cable and deployed from the starboard side. If collection/sampling is done below the water’s surface (also called sub-surface), a weight is attached to the net’s metal frame. A bongo net is an example of a net used for the collection of invertebrate marine organisms at some defined depth below the surface (see photos below).
Multi-sensor water sonde
A bongo net collects organisms by water flowing into the net, which is parallel or horizontal to the water surface at some depth below the surface. Consequently, use of a bongo net requires that the ship moves forward. Deployment of a bongo net requires the use of trigonometry, a favorite math course of mine in high school a long time ago. The length of cable let out by the NOAA deckhand operating the winch with cable does not equal the depth that the bongo net is lowered below the surface. (This would be true if the net was simply dropped straight down over the side of the ship.) Let’s use the drawing below to illustrate this.
Suppose sample collection is to be done at 100m (328 feet) below the water’s surface. More than 100m of cable needs to be let out in order to lower the bongo net to 100m below the water’s surface. How much cable beyond 100m is let out (x) depends on the angle (θ) of the net (and hence cable) to the water’s surface. The angle θ is measured by a protractor attached to the cable and pulley at the position identified with the blue star in the drawing. The angle θ in turn depends on the ship’s forward speed. To calculate the length of cable that needs to be let out, the following trigonometric formula involving right triangles is used: sin θ = cos-1θ = 100mx. The calculated value x is communicated to the NOAA deckhand, who controls the winch that lets out the desired length of cable. When this cable length is reached, retrieval of the bongo net begins.
Duel sampling bongo nets ready for retrieval
The volume of water that contains the marine organisms and that flows through the bongo net is recorded by a torpedo-shaped rotary flowmeter (left photo below), which is suspended by wires or thick fishing line in the middle of the net’s mouth. As water moves past the meter’s end, it smacks into and transfers its momentum to the flowmeter’s propeller, which rotates or spins. The propeller’s shaft in turn is linked to a mechanical counter inside the meter’s body (right photo below). A complete revolution of the propeller equates to a certain number of counts and that is related to a certain volume of water that has flowed past the meter. The mathematical difference between the two numbers recorded before the net’s deployment and after the net’s retrieval is plugged into a mathematical formula to obtain the estimated total volume of water that flowed through the net’s mouth during the time of collection. Consequently, the weight or number of biomass collected by the net can be related to the volume of water in which the biomass was found. This gives an idea about the density of biomass (weight or number of biomass units per volume seawater, g/m3) in a horizontal column of seawater at a given depth and site. In tomorrow’s log I’ll talk about what marine organisms a bongo net collects (including photos) and also discuss and describe the three other nets used on this cruise to collect marine invertebrates.
Mechanical counter in flowmeter
Personal Log
So far after one full day at sea, I haven’t experienced any indications of sea sickness in spite of rough seas (see weather forecast at beginning of log). Four other science team members haven’t been as fortunate. I didn’t witness any visible bioluminescent surface events on the early morning shift (0100 to 0500). I walked to the ship’s bow since this would likely be the best place to witness bioluminescence given all the agitation of seawater there. I left a bit disappointed but there are still five days remaining. The CTD and both the DO and chlorophyll probes (sensors) operated without any problems.
Bob and I communicate well and have similar personalities and intellectual interests. Before carrying out a task we discuss how it’s to be done and then agree to do it as discussed and in the order discussed. Communication is critical because when sampling for biological organisms for example, the nets have large, heavy weights attached so once the net is lifted from the ship’s deck for deployment the weight is airborne so to speak and free to move without resistance. Getting clobbered in the head or chest obviously would not be pleasant. The bongo net uses a 75 pound weight and the net’s solid metal frame must weigh another 25 pounds. Caution and paying attention are paramount once 100 pounds are lifted from the deck, suspended from a cable free to move about with the rolling and pitching of the ship with only air providing any sort of resistance against its movement.
Rotary flowmeter
Bob and I have delegated certain tasks between us. We agreed that when a net is deployed, he will always control the net’s upper halve where the net’s “mouth” and weight are located; I in turn will control the net’s bottom halve where the netting and sample containers or cod ends are located. When the net is ready to be lifted from the sea and returned to the ship’s deck, the tasks for retrieval are the same as for deployment, though in reverse order from deployment. Before the net is lifted shipboard, it’s washed or rinsed top to bottom with seawater from a garden hose that gets seawater pumped directly from the Pacific. Washing is necessary because the collected marine organisms adhere to the net’s mesh so in order to get them into the sample container (cod end) at net’s end they must be “forced” down into the cod end. Once the net is shipboard, the cod end and collected organisms are emptied into a sample jar, sample preservative is added, and the container is labeled appropriately.
