Karah Nazor: Sorting Protocol and the Ubiquitous Tunicates of the Central CA Coast: Salps and Pyrosomes, May 30, 2019

NOAA Teacher at Sea

Karah Nazor

Aboard NOAA Ship Reuben Lasker

May 29 – June 7, 2019

Mission: Rockfish Recruitment & Ecosystem Assessment

Geographic Area: Central California Coast

Date: May 30, 2019

Last night I fell asleep, twice, at the lab bench in between trawls, since I am still adjusting to being on the night shift.  We worked from 9:00 P.M. to 6:30 A.M. After the shift I had a nice hot shower and slept a solid 9 hours from 7:00 AM to 4:00 PM.  Hopefully, I will be less drowsy tonight!

Upon waking, I went to the galley and grabbed some Raisin Bran and coffee and took it up to the flying bridge to hang out with Ornithologist Brian Hoover.  Our current location is in the middle of the Channel Islands, an area I know something about because my friend Evan Morrison, mentioned in my first blog, helps with the Channel Islands Swimming Association, and I would like to swim between these islands one day.  Lauren Valentino, Flora Cordoleani, Ily Iglesias and I congregated on the flying bridge and decided we should exercise. We joined Flora in her squat challenge (80 squats on this particular day), followed by 5 minutes of planking and a bit of erging.  Half of female members of the fish sorting team are avid rock climbers. They did lots of pull-ups using the rock ring climbing training holds that are installed there.

It felt nice and warm when the ship stopped for deployment of the Conductivity, Temperature and Depth (CTD) Rosette, and it got chilly again as the wind picked up when the ship started moving again. We saw a few whale spouts in the distance and at 5:30 P.M. we went down to the galley for a delicious meal of steak and mashed potatoes.  I am beginning to really appreciate how nice this whole experience has been in terms of amenities. The NOAA Reuben Lasker first set launch in 2014 and is a state of the art fisheries vessel with a sophisticated acoustics lab, fish lab, dynamic positioning system, CTD, etc., but is ALSO equipped with creature comforts including a movie lounge, an ice cream cooler loaded with ice cream sandwiches, snickers, fruit pops, you name it, and my personal favorite – a coffee bar where all coffee is freshly ground, an espresso machine, and all varieties of milk and creamers, including Reese’s cup whipped cream. The mattress in my stateroom bunk is quite comfortable and the shower gets hot within seconds! I doubt it can get much better than this for a research experience at sea?

Game Plan and Trawling Line: Point Sal line with five 15 minute hauls.

I am familiar with the sorting protocol now. The catch is dropped from the net into the bucket by members of the deck crew and survey tech, with the oversight of Keith Sakuma, Chief Scientist and NOAA Operations Officer Keith Hanson.  The bucket is immediately placed in the fish lab and this is when the fish sorting team starts our work.

Cobb Trawl net
Dropping the catch from the Cobb Trawl net into the bucket.
fish on a sorting tray
A volume of fish just placed on a sorting tray. This catch has a lot of anchovies, krill, and California smoothtongues.
Separating the krill
Separating the krill from the myctophids, Northern anchovies, and California smoothtongues.
Sorting fish group photo
Team Red Hats sorting fish. NOAA’s Keith Hanson in the rear left side.


We start by carefully picking through a 2000 mL or 5000 mL volume of the harvest, depending on Keith Sakuma’s initial assessment of the species density and volume in the bucket.  The first volume of catch to be sorted is evenly dispersed onto four white sorting trays arrayed on the main lab bench. Once you have a pile of the catch on your tray, you start to separate them into piles of different types of organisms, such as Northern anchovies, ctenophores, krill, salps, pyrosomes, Californian smoothtongues, squid, rockfish, myctophids, and young of year (YOY) fish.  I prefer to use my hands for sorting while others use forceps. Once sorted, we count the number of individuals for each species. If we have difficulty identifying an animal that we have not yet seen, we ask Keith Sakuma or a more experienced team member to help with identification. YOY fish, some in larval form, are particularly difficult for me.

Once sorted and counted, we verbally call out the common name and number of organisms to Keith Sakuma who manually records the data in a 3-ring binder for the lab hard-copy.   For smaller organisms, such as krill or salps, or in hauls with a high number of any particular species, it would be quite tedious to pick out and count each individual in the total haul.  This is why we start with a small subsample volume or 0.5, 2 or 5L, count the individuals in that small volume, establish the ratio for the number of individuals in that volume, and then extrapolate and calculate by the total volume of the haul.  For example, if we counted 97 pyrosomes in the initial 5L sort, and we collected a total of 1000L, then we can say that there are 19,400 pyrosomes in the haul.

Chief Scientist Keith Sakuma
Chief Scientist Keith Sakuma recording the data from a haul during sorting.

Once 20 individuals of each species have been called out, we no longer have to count that species since the ratio for this catch has already been established and to expedite sorting the rest of the volume.  Following sorting, the length of the twenty representatives of each species is measured using electronic calipers and the values populate on an Excel spreadsheet. After measuring, specimens requested by various research institutes including Scripps Institution of Oceanography, Moss Landing, and Monterey Bay Aquarium Research Institute (MBARI) are collected, labelled and frozen.

Flora Cordoleani
Flora Cordoleani keeping track of which specimens are to be preserved for various research groups.
Keith Sakuma bagging specimens to send to collaborators.

Creature(s) feature: Salps and Pyrosomes. 

Salps What are these strange gelatinous organisms in our catch that look like little puddles of clear jelly with a red, green, yellow, and brown digestive organ in the center?  They are goopy, small and slippery making them difficult to pick up by hand. They float on the sea surface and are ubiquitous in our hauls BUT NOBODY KNOWS ABOUT THEM.

These creatures are called salps and belong to the subphylum Tunicata. Tunicates have a notochord in their early stage of life which makes them members of the phylum Chordata, to which humans also belong. Having a transparent body is a way escape being preyed upon.

A group of salps. This species is dime to quarter sized and this number of salps occupies a volume of ~10-15 ml once placed in a beaker.
Salp digestive organs.

Salps are planktonic tunicates  That can be found as individual salps or in long chains called blastozooids.   The salps shown in the photo below were individuals and were notable in most of our hauls. Individual salps in this pile are dime to quarter sized and occupy a volume of ~10-15 ml. We measured the volume of salps in every haul.

While on the topic of salps, I will tell you about a cool 1 inch long salp parasite I found on my sorting tray (see image below). Keith Sakuma explained that it was a deep sea amphipod called Phronima which is a parasitoid that takes up residence inside of a salp’s body, eats the salp’s organs, and then lays its eggs inside of the salp. The King-of-the-salmon, Trachipterus altivelis, (which we are also catching) uses its protrusible jaw to get inside of the salp just to eat this amphipod!

Phronima amphipod
Phronima amphipod – lives and reproduced in salp after eating the salp’s organs. King-of-the-salmon fish use their protrusible jaws to eat the amphipod.
King-of-the-salmon, Trachipterus altivelis
King-of-the-salmon jaw protruded
King-of-the-salmon, Trachipterus altivelis, who preys upon phronima living inside of salp, with jaw protruded.
A large haul full of salps.

Another type of salp we keep catching is Thetys vagina, a large solitary species of nektonic salp that feeds on plankton, such as diatoms, and is an important carbon sink in the ocean. Thetys has an external surface, or test, that is covered with bumps and ridges, as seen in the photo below.

Thetys vagina, the twin-sailed salp.
Thetys vagina, the twin-sailed salp.
internal filtering organ
The internal filtering organ of Thetys vagina.
Kristin Saksa examining a larger Thetys
Kristin Saksa examining a larger Thetys vagina, or the twin-sailed salp. The dark colored tentacles are downward facing. This is the siphon where water enters the sac-filled body.

Pyrosomes Pyrosoma atlanticum are another type of planktonic tunicate which are very numerous in most of our hauls. Pyrosomes look like bumpy pink hollow tubes with openings on both ends. They are rigid in structure and easy to pick up by hand, whereas salps are goopy and difficult to pick up by hand.  We have collected some pyrosomes that are 13 inches long, while most are in the 4-6 inch range. The small pyrosomes look like clear Tic Tacs, but they do not taste as such.

Pyrosoma atlanticum
Pyrosoma atlanticum, with an ~6 inch specimen on the left and small pyrosomes on the right.

How can pyrosomes be so ubiquitous just 20 miles or so off of the Central California Coast, but I have never seen one that has floated up on the beach or while swimming?

Pyrosoma atlanticum are also planktonic tunicates, but are colonial organisms made up of many zooids held together by a gelatinous structure called the tunic. One end of the tube is wide open and filters the water for zooplankton and phytoplankton, while the other end is tighter and resembles a diaphragm or sphincter. The pyrosomes we harvested appeared in diverse array of pinks and purples.  Pyrosomes are believed to harbor intracellular bioluminescent bacteria. Pyrosomes are drifting organisms that swim by beating cilia lining the branchial basket to propel the animals through the water and create a current for filter feeding. 

Pyrosome rainbow
Pyrosoma atlanticum assorted by color.
Kristin Saksa
Moss Landing Graduate Student Kristin Saksa excited about the large haul of Pyrosoma atlanticum.
Pyrosoma atlanticum high-five.

Julia West: Science Is About the Details, March 29, 2015

NOAA Teacher at Sea
Julia West
Aboard NOAA ship Gordon Gunter
March 17 – April 2, 2015

Mission: Winter Plankton Survey
Geographic area of cruise: Gulf of Mexico
Date: March 29, 2015

Weather Data from the Bridge

Time 1600; clouds 35%, cumulus; wind 170 (S), 18 knots; waves 5-6 ft; sea temp 24°C; air temp 23°C

Science and Technology Log

We have completed our stations in the western Gulf! Now we are steaming back to the east to pick up some stations they had to skip in the last leg of the research cruise, because of bad weather. It’s going to be a rough couple of days back, with a strong south wind, hence the odd course we’re taking (dotted line). Here’s the updated map:

sampling stations 3/29/15

Here’s where we are as of the afternoon of 3/29 (the end of the solid red line. We’ve connected all the dots!


I had a question come up: How many types of plankton are there? Well, that depends what you call a “type.” This brings up a discussion on taxonomy and Latin (scientific) names. The scientists on board, especially the invertebrate scientists, often don’t even know the common name for an organism. Scientific names are a common language used everywhere in the world. A brief look into taxonomic categories will help explain. When we are talking about numbers, are we talking the number of families? Genera? Species? Sometimes all that is of interest are the family names, and we don’t need to get more detailed for the purposes of this research. Sometimes specific species are of interest; this is true for fish and invertebrates (shrimp and crabs) that we eat. Suffice it to say, there are many, many types of plankton!

Another question asks what the plankton do at night, without sunlight. Phytoplankton (algae, diatoms, dinoflagellates – think of them like the plants of the sea) are the organisms that need sunlight to grow, and they don’t migrate much. The larval fish are visual feeders. In a previous post I explained that they haven’t developed their lateral line system yet, so they need to see to eat. They will stay where they can see their food. Many zooplankton migrate vertically to feed during the night when it is safer, to avoid predators. There are other reasons for vertical migration, such as metabolic reasons, potential UV light damage, etc.

Vertical migration plays a really important role in nutrient cycling. Zooplankton come up and eat large amounts of food at night, and return to the depths during the day, where they defecate “fecal pellets.” These fecal pellets wouldn’t get to the deep ocean nearly as fast if they weren’t transported by migrating zooplankton. Thus, migration is a very important process in the transport of nutrients to the deep ocean. In fact, one of the most voracious plankton feeders are salps, and we just happened to catch one! Salps will sink 800 meters after feeding at night!


Salp caught in the neuston sample. Salps are a colony of tunicates (invertebrate chordates for you biology students – more closely related to humans than shrimp are!)

Now it’s time to go back into the dry lab and talk about what happens in there. I’ll start with the chlorophyll analysis. In the last post I described fluorescence as being an indicator of chlorophyll content. What exactly is fluorescence? It is the absorption and subsequent emission of light (usually of a different wavelength) by living or nonliving things. You may have heard the term phosphorescence, or better yet, seen the waves light up with a beautiful mysterious light at night. Fluorescence and phosphorescence are similar, but fluorescence happens simultaneously with the light absorption. If it happens after there is no light input (like at night), it’s called phosphorescence.


An example of phosphorescence. We haven’t seen it yet, but I hope to! (From eco-adventureholidays.co.uk)

Well, it is not just phytoplankton that fluoresce – other things do also, so to get a more accurate assessment of the amount of phytoplankton, we measure the chlorophyll-a in our niskin bottle samples. Chlorophyll-a is the most abundant type of chlorophyll.

We put the samples in dark bottles. Light allows photosynthesis, and when phytoplankton (or plants) can photosynthesize, they can grow. We don’t want our samples to change after we collect them. For this same reason, we also process the samples in a dark room. I won’t be able to get pictures of the work in action, but here are some photos of where we do this.

chlorophyll lab

This is the room where we do the chlorophyll readings.

We filter the chlorophyll out of the samples using this vacuum filter:

chlorophyll filter

Each of these funnels filters the sea water through a very fine filter paper to capture the chlorophyll.

The filter papers are placed in test tubes with methanol, and refrigerated for 24 hours or so. Then the test tubes are put in a centrifuge to separate the chlorophyll from the filter paper.

filter paper for chlorophyll

Some of the test tubes for chlorophyll readings, and the filter paper. This box costs about $100!

The chlorophyll values are read in this fancy machine. Hopefully the values will be similar to those values obtained during the CTD scan. I’ll describe that next.


This fluorometer reads chlorophyll levels.

While the nets and CTD are being deployed and recovered, one person in the team is monitoring and controlling the whole event on the computer. I got to be this person a few times, and while you are learning, it is stressful! You don’t want to forget a step. Telling the winch operator to stop the bongos or CTD just above the bottom (and not hit bottom) is challenging, as is capturing the “chlorophyll max” by stopping the CTD at just the right place in the water column.

Bongo graph

This is the graph that comes back from the SeaCAT on the bongo. We are interested in the green line, which shows depth as it goes down and comes back up.

The dry lab

Here I am trying my hand at the computers. The monitor on the left is the live video of what is happening on deck (see the neuston net?). Photo by A.L. VanCampen


CTD scan

This is the CTD graph after it has been completed. The left (magenta) line is the chlorophyll, and the horizontal red lines are where we have fired a bottle and collected a sample. Notice the little spike partway down. That is the chlorophyll max, and we try to capture that when bringing it back up. The colored chart shows columns of continuous data coming in.

Here’s another micrograph of larval fish. Notice the tongue fish, the big one on the right. It is a flatfish, related to flounder. See the two eyes on one side of its head? Flatfish lie on the bottom, and have no need for an eye facing the bottom. When they are juveniles, they have an eye on each side, and one of the eyes migrates to the other side, so they have two eyes on one side! Be sure to take the challenge in the caption!

Larval fish 2

There is a cutlass fish just right of center. Can you find the other one? How about the lizard fish? Hint – look back at the picture in the last post. Photo credit Pamela Bond/NOAA

Personal Log

It’s time to introduce our intrepid leader, Commanding Officer Donn Pratt, known as CO around here. CO lives (when not aboard the Gunter) in Bellingham, WA. He got his start in boats as a kid, starting early working on crab boats. He spent 9 years with the US Coast Guard, where he had a variety of assignments. In 2001, CO transferred to NOAA, while simultaneously serving in the US Navy Reserve. CO is not a commissioned NOAA officer; he went about his training in a different way, and is one of two US Merchant Marine Officers in the NOAA fleet. He worked as XO for about seven years on various ships, and last year he became CO of the Gordon Gunter.

CO is well known on the Gunter for having strong opinions, especially about food and music. He loves being captain for fish research, but will not eat fish (nor sweet potatoes for that matter). A common theme of meal conversations is music; CO plays drums and guitar and is a self-described “music snob.” We have fun talking about various bands, new and old.

CO Donn Pratt

CO Don Pratt on the bridge.

One of the most experienced and highly respected of our crew is Jerome Taylor, our Chief Boatswain (pronounced “bosun”). Jerome is the leader of the deck crew. He keeps things running smoothly. As I watch Jerome walk around in his cheerful and hardworking manner, he is always looking, always checking every little thing. Each nut and bolt, each patch of rust that needs attention – Jerome doesn’t miss a thing. He knows this ship inside and out. He is a master of safety. As he teaches the newer guys how to run the winch, his mannerism is one of mutual respect, fun and serious at the same time.

Jerome has been with NOAA for 30 years now, and on the Gunter since NOAA acquired the ship in 1998. He lives right in Pascagoula, MS. I’ve only been here less than two weeks, but I can see what a great leader he is. When I grow up, I want to be like Jerome!

Jerome Taylor

Chief Bosun Jerome Taylor, refusing to look at the camera. No, he’s not grilling steaks; he’s operating the winch!


Challenge Yourself!

OK, y’all (yes, I’m in the south), I have a math problem for you! Remember, in the post where I described the bongos, I showed the flowmeter, and described how the volume of water filtered can be calculated? Let’s practice. The volume of water filtered is the area of the opening x the “length” of the stream of water flowing through the bongo.

V = area x length.

Remember how to calculate the area of a circle? I’ll let you review that on your own. The diameter (not radius) of a bongo net is 60 cm. We need the area in square meters, not cm. Can you make the conversion? (Hint: convert the radius to meters before you calculate.)

Now, that flow meter is just a counter that ticks off numbers as it spins. In order to make that a usable number, we need to know how much distance each “click” is. So we have R, the rotor constant. It is .02687m.

R = .02687m

Here’s the formula:

Volume(m3) = Area(m2) x R(Fe – Fs) m

Fe = Ending flowmeter value; Fs = Starting flowmeter value

The right bongo net on one of the stations this morning had a starting flowmeter value of 031002. The ending flowmeter value was 068242.

You take it from here! What is the volume of water that went through the right bongo net this morning? If you get it right, I’ll buy you an ice cream cone next time I see you! 🙂


Sunset from the Gordon Gunter as we are heading east.


Mary Anne Pella-Donnelly, September 18, 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 18, 2008

Weather Data from the Bridge 
Latitude: 3543.3896 N Longitude: 12408.3432 W
Wind Direction: 129 (compass reading) SE
Wind Speed: 7.8 knots
Surface Temperature: 17.545

Blue shark seen on 9/18

Blue shark seen on 9/18

Science and Technology Log 

Today was an exciting one scientifically. The team has been examining all of the oceanographic data so far in order to pinpoint frontal edges for further data collection. They selected a point last night that might contain a biologically rich layer and hopefully, with jellies. After closely looking over every thing they have learned on this trip so far and plotting a destination to sample, we traveled to that station. We found an ocean water ‘river’ full of kelp, moon jellies, sea nettles and pelagic birds! It was exactly where the team predicted there might be a biotic stream!! This confirmed that offshore habitats can be found using oceanographic data and satellite imaging.  There certainly were offshore areas that would give leatherbacks a chance to eat their fill.  And through that period, the sun came up!  With only a slight breeze, the flying deck was warm and relaxing. It put us all into excellent spirits.

Personal Log 

Ray Capati shows off his Turtle Cake. (photo by Karin Forney)

Ray Capati shows off his Turtle Cake.

A few days ago, the chief steward made a cake- there are daily baked goods offered in the mess hall. This cake, however, was decorated for the LUTH Survey with turtles, kelp and jellyfish!  Today would have been another good day for that treat.  It is also time to get some pictures with C.J. our school mascot.  He was pretty happy to get out and see the ship.  He even tried to help up on the flying bridge, but without thumbs, it was hard for him to enter in observation comments.

Animals Seen Today 
Moon jellies Aurelia labiata, Sea nettle jellies Chrysaora fuscescens, Salps Salpida spp., Sea gooseberries Pleurobrachia bachei, Red phalaropes Phalaropus fulicaria, Cuvier’s beaked whales Ziphius cavirostris, Common dolphins Delphinus delphis, Blue sharks Prionace glauca, and Arctic terns Sterna paradisaea.

C.J. helps out on the flying bridge.

C.J. helps out on the flying bridge.

Questions of the Day 

  1. What might be some oceanographic conditions that would create a water mass filled with kelp and jellyfish?
  2. What other organisms (than we observed) might be attracted to such a water mass?

Rebecca Bell, August 16, 2008

NOAA Teacher at Sea
Rebecca Bell
Onboard NOAA Ship Delaware II 
August 14-28, 2008

Mission: Ecosystems Monitoring Survey
Geographical Area: North Atlantic
Date: August 16, 2008

Weather Data from the Bridge 
Time:   1807 (GMT)
Latitude:  36.05.40 N Longitude: 75.24.30 W
Air Temp 0C: 25.3 0C
Sea Water Temp:  26.7 0C

On left: small barrel-shaped copepods; Center: white, arrow worms; Top right: amphipods

On left: small barrel-shaped copepods; Center: white, arrow worms; Top right: amphipods

Science and Technology Log 

The most common zooplankton we have seen so far are salps, amphipods, arrow worms and copepods. Pteropods (sea butterfly) have been in a number of samples but are not numerous. Salps look like clear, jelly-like marbles. We’ve encountered these animals in warm, shallow water. They are holoplanktonic relatives of sea squirts (Urochordata). Salps are filter feeders, using cilia to move suspended particles from the water. They feed by pumping water through a sieve to remove bacteria and nanoplankton, and are thus, a very important link in the food chain. Some species of salps form huge chains by budding. They show both sexual and asexual life stages. For more about salps and photos see this website.

Amphipods are also extremely common crustaceans. There is no carapace (shell-like covering), but their bodies are flattened side-to-side, much like a shrimp.  Their bodies are segmented with 6 segments in the head, 8 in the thorax and 6 in the abdomen.1 They have a brood pouch on their thoracic limbs. They have a variety of limbs used for feeding, crawling or jumping. One group lives off a host, feeding on salp tissues. Some types live in tubes; others use their back legs to anchor themselves while they sway to and fro in the water column. Some species swim rapidly while others stay near the bottom of the ocean. Many will move vertically in the water column, moving near the surface during the day, and sinking again at night. The species we are catching has large compound eyes that can be seen by the naked eye. For more about amphipods, visit this website. 

Becky examines the catch using a hand lens.

Becky examines the catch using a hand lens.

Copepods are very common crustaceans, with more than 200 species and 10,000 families. 2 We have found more of these than any other organism. Copepods are omnivorous. Some groups graze on microplankton; other groups of copepods prey on larger plankton, including other copepods. They are an important link in the food chain as well, moving carbon from a microscopic level to a larger trophic (feeding) level. They are eaten by jellyfish, fish, comb jellies and arrow worms. Copepods have “antennae” that have special sensors that detect water movement around them. They are able to move toward prey by contracting a muscle that runs in a circle around their bodies. For more about copepods, visit this website.

Arrow worms (Chaetognatha) are common along coasts, but we did not catch any out away from shore. Arrow worms are classified in their own group, distinct from Annelids (earthworms), round worms and flatworms, which are all separate groups of worms. They are predators, often waiting to ambush their prey. When their cilia detect prey, usually copepods, the arrow worm contracts 2 muscles that run dorsally and ventrally (top to bottom) to strike. Their mouths have spines that grab the prey and smaller “teeth” produce a venom that subdues the prey. The prey is swallowed whole. Arrow worms, in turn, are eaten by jellyfish, copepods and fish.

Sea Butterflies were not common, but they are very interesting. Sea butterflies (pteropods) are holoplanktonic mollusks, related to snails. Basically, they are shell-less snails. Their foot is modified into winglike structures (ptero= winged) that they flap as they swim through the water. Their bodies are tube-shaped and clear. The bodies and wings of the species we have seen are an orange-pink color. They are predators and are preyed upon by fish, sea birds and whales.


Information for these paragraphs were modified and combined from the following sources: 1 Newell, G.E. and Newell, R.C.; Marine Plankton: A Practical Guide; 5th edition; 1977; Hutchinson & Co; London.2 Johnson, William S. and Allen, Dennis M.; Zooplankton of the Atlantic and Gulf Coasts: A Guide to Their Identification and Ecology; 2005; Johns Hopkins University Press.

Personal Log 

This morning we saw dark clouds in the distance. You could see rain falling from the clouds. Nearby we could see the tail of a water spout disappearing into the clouds.  We sampled our southern-most station and are now heading north along the coast just south of Chesapeake Bay. The samples we are pulling now have a lot of diatoms.

Rebecca Bell, August 15, 2008

NOAA Teacher at Sea
Rebecca Bell
Onboard NOAA Ship Delaware II 
August 14-28, 2008

Mission: Ecosystems Monitoring Survey
Geographical Area: North Atlantic
Date: August 15, 2008

Weather Data from the Bridge 
Latitude:  3846.7 Longitude: 7302.1
Temp 25.4 C

Bongo net

Bongo net

Science and Technology Log 

In the last post, I explained WHY we are collecting zooplankton. This post will illustrate HOW the samples are taken.

The samples are collected using a device called a bongo net (Yes, like the musical instrument).  You can see the metal rings and the nets hang from the metal rings. One net is marked with red and the other green. This allows you to tell the two nets apart. The samples from the red side will be used for the ichthyoplankton study. The samples from the green side will be used for the zooplankton study.

The white device is the CTD (Conductivity, Temperature, Depth). You attach it to the bongo net frame and turn it on. The CTD takes measurements on the way into the water and on the way out of the water. When the bridge clears you, the computer operator (inside) tells the hydraulics operator to start letting out the line and at what speed to let it out and bring it in. You calculate the amount of time in and out using a chart that is based on changing depth. You have to calculate it so you get at least a 5-minute tow.



Now the bongo nets are raised on the A-frame. You can see the CTD above the bongos (right picture) and there is a lead weight beneath and between the nets. Next, the A-frame moves the nets over the side of the ship and they are lowered into the water. You cruise for at least 5 minutes. The idea is to get within 5 meters of the bottom, then start bringing the nets back in. The computer operator keeps track of where the bottom is. The idea is to stop the line going out in time so the nets don’t hit the bottom and pull up a bunch of sand. Then you just have to wait for the tow, and eventually for the nets to come back up.

The bongos are removed from the A-frame and brought into the wet lab. You use the hose to wash the plankton down to the bottom of the net. The bottom of the net is put into the sieve. When the net is hosed down to the sieve end, you untie the bottom of the net and let the plankton wash into the sieves. The mesh captures zooplankton, but lets smaller phytoplankton through. Finally you rinse the plankton from the sieves into a jar with 5% formalin for preservation. A label is put into the jar as well as on top of the jar, stating station number, date and time.

NOAA Teacher at Sea, Becky Bell, assists in deploying the bongo nets.

NOAA Teacher at Sea, Becky Bell, assists in deploying the bongo nets.

Personal Log 

We had a fire drill and an “abandon ship” safety drill. In the picture to the right, I am wearing a survival suit, lovingly known as a “Gumby suit”. If you abandon ship, you have to run to the deck and put on this suit. It is one piece, with inflatable neck rest, whistle and flashing pocket light so you can be spotted. You have to lay the suit out on deck, and sit down in it. Feet go in first, then you stand up and pull the rest over your head, find the arms etc. Look at the look on my face. Not too sure about this! The front flap closes to show only your eyes–on me a little higher. You should try zipping the front zipper with thick rubber gloves that are too big for you. It reminds me of the astronauts trying to fix the space station. I have a new appreciation for how difficult it is too, like, HOLD anything. The best news yet–we get to practice next week again.

Deploying the Bongo net

Deploying the Bongo net

The A-frame

The A-frame

The nets begin to emerge from the water.

The nets begin to emerge from the water.

Becky waits for the nets to come back up after the tow

Waiting for the nets to come back up after the tow

Becky rinsing down the net

Becky rinsing down the net

Then she puts the plankton into a jar for preservation

Then she puts the plankton into a jar for

Becky dons her survival suit during a safety drill.

Becky dons her survival suit during a safety drill.


Rebecca Bell, August 14, 2008

NOAA Teacher at Sea
Rebecca Bell
Onboard NOAA Ship Delaware II 
August 14-28, 2008

Mission: Ecosystems Monitoring Survey
Geographical Area: North Atlantic
Date: August 14, 2008

Weather Data from the Bridge 
Time:   134628 (GMT)
Latitude:  40.33.06N Longitude: 72.47.36W
Air Temp 0C: 22.1
Sea Water Temp:  22.3 0C

NOAA Ship Delaware II

NOAA Ship Delaware II

Science and Technology Log 

We sailed from Woods Hole, MA on Wednesday, August 13, 2008 on the first of three legs as part of the Ecosystem Monitoring Program. There are two main objectives of the cruise. The first is to see how well the fish population is doing by sampling and counting fish larvae. The number of fish is important to the fisheries industry- those folks who bring cod and other fish to your table. The second objective is to monitor the zooplankton population. Fish feed on the zooplankton, so a healthy zooplankton population may mean a healthier fish population. We also are monitoring the physical properties of the water; in this case, salinity and temperature. These influence where fish larvae and zooplankton can survive and where and how far they can be dispersed.

There are 125-130 sites randomly selected for sampling. At each site, a pair of bongo nets are dropped and the two samples are collected side-by-side, for a total of 250-260 samples. One sample is designated for the ichthyoplankton (fish larvae) study, and the other for the study of zooplankton composition, abundance and distribution. Near-surface along-track chlorophyll-a fluorescence, which indicates abundance of phytoplankton (i.e. food for the zooplankton), water temperature and salinity are constantly measured with the vessel’s flow-through sampling system. We will also be collecting a separate set of samples as we approach the Chesapeake Bay. These will be used to study aging of fish larvae.

Zooplankton include both unicellular and multicellular organisms. Many can easily be seen with the naked eye. Zooplankton can be classified in a number of ways. One way is to classify them by life history. Holoplankton are those that are planktonic during their entire life cycle (lifers). Meroplankton refers to those plankton in a developmental stage, like eggs and larvae (shorttimers). These larvae will grow into larger organisms such as jellyfish, mollusks, fish, starfish and sea urchins, crustaceans, copepods and amphipods.

The term “plankton” comes from a Greek word for “wanderer” or “drifter”.1 This may imply that these organisms are passively moved about by currents. However, many can power around on their own, using several different methods such as cilia, muscle contraction, or appendages on the head, thorax or abdomen. They also move vertically in the water column, up toward sunlight during daylight hours and downward at night. Krill (whale food), on the other hand, do the opposite- travel downward during the day and up at night.

The first two samples contained a vast number of salps. A salp is holoplanktonic and is related to sea squirts (urochordates). They are filter feeders, catching bacteria and extremely small plankton in mucous-covered “nets” that act as sieves. Salps are an important part of the ocean food chain.

Samples 3-5 show a greater variety of organisms- comb jellies (ctenophores), arrow worms (Chaetognatha) fish larvae and amphipods. Samples 6-8 are dominated by copepods. There are salps, too, but not nearly as many (about 1/3 fewer) as we saw in the first 2 samples.

So I am looking at these results and wondering: Are there patterns to the distribution of these assemblages? Are salps found in warm water or cooler water?  Does temperature matter at all? Do they like deeper water?  Higher or lower salinity? Combinations of any of these? Are they found where another organism is found?

Personal Log 

We began our first work shift today, er, last night, um, this morning at 3 a.m. I work the 3 a.m. to 3 p.m. shift. That means to bed around 7pm., rise and shine at 2:30 a.m. Well, rise, anyway. Not much shining till later.

As I sat on the deck in darkness, waiting to reach our first sample site, I spotted the light from another ship on the horizon. I watched as the light traveled up a wave, then down a wave then up, up, up, up, still up. I could not believe how high it was going, knowing we were doing the same thing. It’s a good thing it doesn’t feel like that. We are now heading south, back towards the Chesapeake Bay. It is getting hotter and muggier, just like home.

We saw dolphins today. A large leatherback turtle was spotted from the bridge. The 3pm- 3am. shift reported seeing flying fish.

Animals Seen Today 

  • Salps
  • Amphipods
  • Copepods
  • Ctenophores
  • Chaetognaths (arrow worms)
  • Fish larvae
  • Sea butterfly
  • Dolphins
  • Gulls (4 species)

1 Source: Online Etymology Dictionarywww.etymologyonline.com.