Dana Chu: May 17, 2016

NOAA Teacher at Sea
Dana Chu
On Board NOAA Ship Bell M. Shimada
May 13 – 22, 2016

Mission: Applied California Current Ecosystem Studies (ACCESS) is a working partnership between Cordell Bank National Marine Sanctuary, Greater Farallones National Marine Sanctuary, and Point Blue Conservation Science to survey the oceanographic conditions that influence and drive the availability of prey species (i.e., krill) to predators (i.e., marine mammals and sea birds).

Geographic area of cruise: Greater Farallones, Cordell Bank, and Monterey Bay National Marine Sanctuaries

Date: Tuesday, May 17, 2016

Weather Data from the Bridge
Clear skies, light winds at 0600 increased to 18 knots at 0900, 6-8 feet swells

Science and Technology Log

Ahoy from the Bell Shimada! Today, I will explain three of the tools that are deployed from the side deck to obtain samples of the water and the ocean’s prey species.

First off we have the Harmful Algal Bloom Net, also known as the HAB Net, which is basically a 10-inch opening with a 39-inch fine mesh netting attached to a closed end canister. The HAB net is deployed manually by hand to the depth of 30 feet three consecutive times to obtain a water sample. The top fourth of the water collected is decanted and the remaining water (approximately 80ml) is transferred to a bottle which is then sealed and labeled with the location (latitude, longitude), date, time, vertical or horizontal position, and any particular comments. The samples will eventually be mailed off to California Department of Health Services lab for analysis for harmful toxins from algae that can affect shellfish consumers.

Next we have the hoop net, which is pretty much similar in design to the HAB net, except for a larger opening diameter of 3 feet (think hula hoop) and a net length of nine feet. The net tapers off into a closed container with open slits on the sides to allow for water drainage. The purpose of the hoop net to collect organisms that are found at the various depth levels of the deployment. The hoop net is attached to a cable held by the winch. The hoop net is lowered at a specific angle which when calculated with the speed of the vessel equates to a certain depth. The survey crew reports the wire angle sighting throughout the deployment.

Every time the hoop net is brought back up there is a sense of anticipation at what we will find once the canister is open. Coloring is a good indicator. Purple usually indicates a high concentration of doliolids, while a darker color may indicate a significant amount of krill. Phytoplankton usually have a brownish coloring. Many of the hoop net collections from today and yesterday include doliolids and colonial salps, neither are very nutrient dense. Yesterday we also found pyrosomes, which are transparent organisms that resemble a sea cucumber with little bumps and soft thorns along their body. The smallest pyrosome we came upon was two and a half inches with the largest over six inches long. A few small fish of less than one inch in length also showed up sporadically in these collections as well.

The Scientific team is looking for the presence of krill in the samples obtained. The Euphausia pacifica is one of the many species of krill found in these waters. Many tiny krill were found in the various hoop net deployments. On the last hoop net deployment for today and yesterday, larger sized krill of approximately 1 inch) were found. This is good news because krill is the dominant food source for marine mammals such as whales. Ideally it would be even better if the larger krill appeared more frequently in the hoop net samples.

Finally, we have the Tucker Trawl, which is the largest and most complex of the three nets discussed in today’s post. The Tucker Trawl consists of three separate nets, one for sampling at each depth: the top, middle, and bottom of the water column. Like the hoop net, the tucker trawl nets also have a canister with open slits along the side covered with mesh to allow water to drain. All three nets are mounted on the same frame attached to a wire cable held by the winch. As the Tucker Trawl is towed only one net is open at a time for a specific length of time. The net is closed by dropping a weight down along the tow. Once the weight reaches the net opening, it triggers the net to shut and sends a vibration signal up the cable line back to the surface which can be felt by the scientist holding the cable. The net is then towed at the next depth for ten minutes. Once the last net tow has been completed, the Tucker Trawl is brought back up to surface. Similar to the hoop net, the survey tech reads the wire angle throughout the deployment to determine the angle the cable needs to be at in order for the net to reach a certain depth. This is where all the Geometry comes in handy!

As mentioned already, with three nets, the Tucker Trawl yields three separate collections of the nutrients found within the top, middle and bottom of the water column. Once the nets are retrieved, each collection container is poured into a different bucket or tub, and then into a sieve before making it into a collection bottle. If there is a large quantity collected, a subsample is used to fill up a maximum of two bottles before the remainder is discarded back into the ocean. Once the samples are processed, an outside label is attached to the bottle and an interior label is dropped inside the bottle, formalin is added to preserve the sample organisms collected so that they can be analyzed later back in the lab.

Personal Log

It is so good to finally get my sea legs! I am glad I can be of use and actively participate. Cooperative teamwork is essential to getting everything to flow smoothly and on time. The Bell Shimada’s deck crew and NOAA team work hand in hand with the scientists to deploy and retrieve the various instruments and devices.

In the past two days I am getting a lot of hands on experience with deploying the HAB net to assisting with processing samples from the HOOP Net and Tucker Trawl. It’s always exciting to see what we might have collected. I can’t wait to see what the rest of the week may bring. I wonder what interesting finds we will get with the midnight Tucker Trawl samples.

Lesson Learned: Neatness and accuracy are imperative when labeling samples! Pre-planning and preparing labels ahead of time helps streamline the process once the samples are in hand.

Word of the Day:        Thermocline – This is the depth range where the temperature of the water drops steeply. The region above the thermocline has nutrient depleted waters and while the region below has nutrient rich waters.

 

Marilyn Frydrych, September 16, 2008

NOAA Teacher at Sea
Marilyn Frydrych
Onboard NOAA Ship Delaware II
September 15-25, 2008

Mission: Atlantic Herring Hydroacoustic Survey
Geographical area of cruise: New England Coastal Waters
Date: September 16, 2008

The Newston net hanging from a pulley on the A-frame

The Newston net hanging from a pulley on the A-frame

Weather Data from the Bridge 
41.27 degrees N, 70.19 degrees W
Partly Cloudy
Wind out of the W at 19 knots
Dry Bulb Temperature: 26.0 degrees Celsius
Wet Bulb Temperature: 20.9 degrees Celsius
Waves: 2 feet
Visibility: 10 miles
Sea Surface Temperature: 21.6 degrees Celsius

Science and Technology Log

Today started slowly since we were still in transit to our starting position.  All morning there were 15 to 20 terns and gulls flying nearby.  Occasionally we’d spot land birds.  A small yellow-rumped warbler actually flew into the dry lab area of the boat. It was far from where it belonged and probably wouldn’t make it back.  The terns skimmed the water surface, but never actually seemed to touch the water.  Our bird scientists, Marie-Caroline Martin and Timothy White, decided they would deploy a Newston net to try to determine what the birds were eating. The fishermen, who do all the deploying of instruments, hung the net from the A-frame pulley on the starboard side and swung it out over the water. For 20 minutes it bounced in and out of the water never getting more than a foot or so above or below the surface. The Neuston fine mesh net is about 10 feet long and has a mouth about 4 feet by 2 feet.

Jim Pontz, a fisherman, working the A-frame.

Jim Pontz, a fisherman, working the A-frame.

When the fishermen brought it in, it mostly held salp and  jellyfish, but also some small crustaceans which looked like miniature shrimp about 1/2 in. long.  The jellyfish were small, without stingers.  Marie carefully washed the contents of the net down to its opening with a salt water hose.  Then she used her unprotected hands to slide her catch into a glass jar about the size of a medium peanut butter jar. She graciously separated a few of the crustaceans for us to observe. About 11:30 a.m. we finally reached our starting point. The plan was to do parallel north-south transects.  We would cross the east-west transects without stopping . We fished with a huge net off the stern. The chief scientist, Dr Michael Jech, decided when to fish. Sometimes he put the net in to prove that there were no herring there and the echoes he was receiving were correct.  Other times he saw a new signature on the screen and checked to see what it might have been.  Still other times he recognized the herring signature (he’s about 90% accurate) and  fished to determine sizes, sexes, and stomach content.  At other times he had predetermined stations where fishing had been good in the past.

A herring in a clothes basket. Note the brilliant blue stripe on top.

A herring in a clothes basket. Note the brilliant blue stripe on top.

At each 90 degree turn we deployed a CTD – conductivity, temperature, and depth instrument. The instrument measured how easily electricity can flow through the seawater, its conductivity. From this and the temperature and pressure (or depth) the salinity of the water can be determined.  The equations involve the 5th power of both temperature and pressure. They appear to be Taylor’s series approximations.  The CTD is also used to calculate the speed of sound which is important for the accuracy of the sonar equipment.  Only the crew may actually deploy instruments.  None of the scientists touch the instruments going over the side. The scientific crew’s job was to communicate via a handheld radio with the fishermen working the winch and the one putting the instrument into the water.  We told them when to start after we had initialized the computer programs and when to haul back the CTD as it came within a few feet of the ocean bottom. We could simultaneously look at a cam on a nearby monitor showing what was happening at the A frame.  I watched the first time this was done, but with everyone’s help soon caught on and was doing it myself.

Jacquie Ostrom at her post radioing the fishermen when to start the CTD

Jacquie Ostrom at her post radioing the fishermen when to start the CTD

The second time I helped with the CTD we attached a Niskin water bottle to the bottom of the CTD and signaled to have it stopped about half way back up the ever present bottom layer isotherm.  We paused for about a minute as it filled with the surrounding water.  At that point both ends were wide open. A fisherman dropped a messenger, a heavy round metal doughnut, down the line to the bottle.  It tripped a lever which then allowed the lids connected with tremendously strong elastic bands to snap shut.  The tube is a little larger than a 2-liter soda bottle. When we were given the retrieved bottle, we washed out a small, maybe 1-cup, bottle 3 times with the seawater from the Niskin bottle before we filled and capped it and replaced it in its position in a crate.  The water can be used to calibrate the salinity readings the CTD recorded and to determine various other chemicals at that spot of collection in the ocean.

Sunset silhouetting the CTD bottle balancing against one arm of the A-frame.

Sunset silhouetting the CTD bottle balancing against one arm of the A-frame.

Personal Log 

Today being the first full day at sea I was introduced to a wonderful daily ritual. Each morning at about 10:30 the chiefs brought out from the oven their first baked dessert of the day. Today’s was the most perfectly seasoned peach cobbler I’ve ever tasted. Once toward evening we spotted dolphins around the ship. We could occasionally see them jumping through the air. A pair played in the bow wake for a short while. About the same time the crew pointed out to us some three or four pilot whales about 100 yards off the starboard stern. I hadn’t expected to see so much sea life.  This is turning into a very memorable adventure.

 

Mary Anne Pella-Donnelly, September 11, 2008

NOAA Teacher at Sea
Mary Anne Pella-Donnelly
Onboard NOAA Ship David Jordan Starr
September 8-22, 2008

Mission: Leatherback Use of Temperate Habitats (LUTH) Survey
Geographical Area: Pacific Ocean –San Francisco to San Diego
Date: September 11, 2008

CTD deployment

CTD deployment

Weather Data from the Bridge 
Latitude: 3647.6130 W Longitude: 12353.1622 N
Wind Direction: 56 (compass reading) NE
Wind Speed: 25.7 knots
Surface Temperature: 15.295

Science and Technology Log 

One important piece of equipment on many NOAA research ships is the CTD (Conductivity and Temperature with Depth).  This eight chambered water collection device is attached to electronic sensors. When the CTD is deployed below the ocean’s surface, it is dropped carefully to a predetermined depth; today’s was 500 m. All water collection chambers are open for water to flow through. After the oceanographer in charge of deployment examines a computer readout of the CTD after it has been lowered to its’ maximum depth, it is decided at which depths water samples will be collected as the CTD is brought back up.At these intervals, water sample collectors (Niskin bottles) are closed and water collected.  Up to eight samples are collected as it rises to the surface.

CTD reading; salinity, oxygen, pressure, and fluorometer voltage

CTD reading: salinity, oxygen, pressure, and voltage

After the CTD has been secured on deck, each sample is carefully extracted into collection bottles. Each water sample is filtered through a vacuum system in order to extract chlorophyll from that water sample.  The extracted chlorophyll is later run through a fluorometer, which calculates the volume of chlorophyll a and chlorophyll b which indicates the intensity of photosynthetic microorganisms in that layer. Lots of chlorophyll indicates a rich biological region, which may support many types of marine life.  In addition, the CTD collects samples that will be analyzed for the amount of salts they contain in order to confirm the sensors values. Values that change to the left are decreasing. The reading on the top right shows how the temperature, in red, changes very quickly from the surface down to 500 m.  The green indicates some chlorophyll until it drops significantly below 100 m, where light no longer penetrates well. Oxygen levels are in blue, also decreasing with depth.

Questions of the Day 

  1. What is the importance of chlorophyll to marine mammals and amphibians?
  2. Why is an understanding of how pressure and depth below the ocean’s surface are related critical to marine sciences?
Water samples being filtered through a vacuum system to extract chlorophyll.

Water samples being filtered through a vacuum system to extract chlorophyll.

 

Jillian Worssam, July 24, 2008

NOAA Teacher at Sea
Jillian Worssam
Onboard U.S. Coast Guard Vessel Healy
July 1 – 30, 2008

While looking at the collected sediment trap, it is obvious that many unsuspecting pieces of debris were caught within its clutches.

While looking at the collected sediment trap, it is obvious that many unsuspecting pieces of debris were caught within its clutches.

Mission: Bering Sea Ecosystem Survey
Geographic Region: Bering Sea, Alaska
Date: July 24, 2008

One of the pleasures while at sea is the concept of time; which is in a word, timeless. Last night the sun set around three in the morning, and if you had asked me what day it was when I went to bed, I could not have answered. I know the date because I made files prior to this cruise so that I could keep track, in some infinitesimal way, of my journals. Right now I know for sure that I am a day behind in writing, that the cruise will be over in less than a week, I still have a lot more science to learn and this afternoon I am making Apple Crisp for the Morale dinner. These things I know, what I am still learning is the science of a sediment trap.Pat Kelly is from the University of Rhode Island Graduate School of Oceanography, and he is here, in part, to collect sediment samples that float in the ocean.

There are many components to the research Pat is working on; one is in collecting particles sinking vertically in the ocean. By using an established brine (denser NaCl) solution in an array of floating tubes Pat is able to catch these falling sediments. The process is to deploy his trap, a series of tubes for the falling sediments held aloft by floats that drift in the ocean, for no more than 24 hours.

After the brine from the sediment trap is filtered and dried the collected sediments will be analyzed.

After the brine from the sediment trap is filtered and dried the collected sediments will be analyzed.

When collected, Pat will remove the sediments from the brine, looking at the thorium and organic carbon, there is a relationship between these two elements and Pat wants to focus particularly on the carbon. Now this is where it gets sticky for me as I am not a chemical oceanographer. Pat is looking at the carbon flux. The team wants to look at the carbon transfer as it changes from atmospheric carbon, to organic carbon in the oceans, thus taking it out of the carbon cycle.

The scientists making sure the trap is ready before being deployed off the back deck of the vessel.

The scientists making sure the trap is ready before being deployed off the back deck of the vessel.

One of the underlying questions in this component of the HEALY research is how the oceans will respond to all the increased carbon due to global climate change. Pat’s group is actually looking at carbon cycling in many different oceans, with their hypothesis: The arctic will respond faster to increases in carbon (changes more apparent, faster), due to decreased ice, and the fact that it is dark for ½ the year. Think of it this way, after a long dark winter with good nutrient build up, a higher yield is to be expected with 24 hours of sunlight. The sinking particles Pat studies are also very important to the benthos species providing nutrients and food as they sink.

The scientists are carefully retrieving the tubes of brine that for the past 24 hours have collected ocean sediments.

The scientists are carefully retrieving the tubes of brine that for the past 24 hours have collected ocean sediments.

Like many of the scientists on board, Pat is doing multiple investigations. The ocean as I talked about before is layered and Pat’s team is looking at productivity in the mixed layer using 02 isotopes. This data will give the scientists the rate that phytoplankton is growing.

The team also uses radium isotopes to estimate advection of deep water to the surface along the shelf break. The information will tie in with the scientists studying iron. There is belief that the iron is up welled from the sediments in the deep water to the surface layers.

I am still learning about the chemistry of ocean science, and do not fully understand all of Pat’s research. I do though see that everything is intimately linked, that all components of this ecosystem are dependent upon each other and if one component is changed then ALL will change as well.

I hope to never be so jaded as to not appreciate the beauty in nature.

I hope to never be so jaded as to not appreciate the beauty in nature.

Quote of the Day: Come forth into the light of things, let nature be your teacher. -William Wordsworth

FOR MY STUDENTS: No question for today, go out and enjoy the sunset!

Jillian Worssam, July 23, 2008

NOAA Teacher at Sea
Jillian Worssam
Onboard U.S. Coast Guard Vessel Healy
July 1 – 30, 2008

Mission: Bering Sea Ecosystem Survey
Geographic Region: Bering Sea, Alaska
Date: July 23, 2008

Last night I went to bed at four, my wake up call was for seven forty five this morning, needless to say if I have a little difficulty explaining micro-zooplankton there is an excuse.Today I am spending time with Diane Stoeker and Kristen Blattner, both from The University of Maryland Center for Environmental Science.

If she is not at the computer Diane is either at the microscope, the incubators or working on her phytoplankton experiments.

If she is not at the computer Diane is either at the microscope, the incubators or working on her phytoplankton experiments.

Diane and Kristen are studying phytoplankton and micro-zooplankton, and it is amazing how these small components of an oceanic ecosystem are vital for the survival of pretty much the entire environment. Diatoms are small single-celled organisms, called phytoplankton. Diane is studying how fast phytoplankton are eaten by micro zooplankton, and how this “grazing” effects phytoplankton populations.

It is a long process to measure water and extract chlorophyll, Kristen is up for the challenge.

It is a long process to measure water and extract chlorophyll, Kristen is up for the challenge.

Let’s try a visual

Phytoplankton = the microscopic “plants” of the ocean. These organisms photosynthesize and drift with the current. Although some phytoplankton do have locomotive capabilities they cannot swim again the current.

Diatoms are a type of phytoplankton. Zooplankton = small animals who also move with currents and eat phytoplankton as well as micro-zooplankton.

Now enter Diane and Kristen, they look at phytoplankton to find out what is eating them, predominantly micro-zooplankton, and are even looking at their relationship with zooplankton pee and how it might work as a fertilizer for phytoplankton. What these ladies do is collect samples of sea water once a day. They use a mixture of 20% whole sea water and 80% filtered sea water (which removes most of the algae, copepods and protozoa), and a 100% whole sea water sample.

This is part of the larval stage, nauplius of a copepod.

This is part of the larval stage, nauplius of a copepod.

Kristin then strains both types of water pre and post incubation, and will compare the chlorophyll samples. What Kristin is hoping for is that after 24 hours there will be more chlorophyll in the 20/80 sample indicating greater phytoplankton growth, due in part, to the fact that there are fewer predators (micro-zooplankton) in this water. Micro-zooplankton eat nearly 50-60% of the phytoplankton, which they are fertilizing at the same time. This relationship is fundamental to a healthy oceanic ecosystem; you could even say these micro-zooplankton help sustain the growth if phytoplankton in the ocean.

After the 24 hour incubation, samples are taken for further study back at the lab. One specimen they often see is a heterotrophic dinoflagellate. This guy has no chlorophyll and wants to eat phytoplankton; it is in other words a micro-zooplankton.

This little gem does not photosynthesize and locomotors by the little hair like tenacles.

This little gem does not photosynthesize and locomotors by the little hair like tenacles.

As I look at the pictures Diane has taken, I am transported to a word that is so small that to tell the difference between plant is animal is very difficult.

Isn't this a great looking microzooplankton, can you see how it moves?

Isn’t this a great looking microzooplankton, can you see how it moves?

Quote of the Day: The great sea has sent me adrift, it moves me, it moves me, as the weed in a great river. Earth and the great weather move me, have carried me away and moved my inward parts with joy. Uvavnuk Eskimo Song

FOR MY STUDENTS: What other areas of study can we focus on while using microscopes?

Scott Donnelly, April 24, 2008

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

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

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.

Screen shot 2013-04-20 at 4.55.48 AMWhat 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 

Screen shot 2013-04-20 at 4.56.10 AMAfter 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.

 

Scott Donnelly, April 22, 2008

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

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

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

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

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

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

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.

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