Christina Peters: Finding Plankton on Oregon II, July 13, 2013


NOAA Teacher at Sea
Chris Peters
Onboard NOAA Ship Oregon II
July 10 – 19, 2013

Mission: SEAMAP Summer Groundfish Survey
Geographic Area of Cruise: Gulf of Mexico, leaving from Pascagoula, MS
Date: July 13, 2013 

Weather and Location:
Time: 23:24 Greenwich Mean Time (7:24 p.m. in Rockville, MD)
Latitude:  25.5340
Longitude:  -82.0215
Speed (knots):  9.30
Water temperature:  28.90 degrees Celsius
Salinity (PSU = Practical Salinity Units): 35.38
Air temperature:  31.20 degrees Celsius
Relative Humidity:  65%
Wind Speed (knots):  8.92
Barometric Pressure (mb): 1013.34
Depth (m) = 19.20

Science and Technology Log

Our Mission

In my introduction I explained that SEAMAP is a state, federal, and university program.  In fact, there is a managing unit called the SEAMAP– Gulf Subcommittee of the Gulf States Marine Fisheries Commission’s Technical Coordinating Committee who manages the activities and operations, including collecting samples and interpreting data, of the Gulf participants, including the Mississippi Laboratory of NOAA and the states of Louisiana, Mississippi,Texas, Alabama, and Florida, as well as certain universities.  Parts of the program include bottom trawls, CTD deployment, and Bongo and Neuston tows.  The bottom trawls involve towing nets at randomly selected spots for ten to thirty minutes. The sea life caught in the nets, normally shrimp and other animals that live at the bottom of the Gulf, are sorted, identified and measured.  All of the data is recorded and helps to determine where the fish and shrimp are, and how much exists in the Gulf.  Because the NOAA Laboratory and the states have worked so well together on this project, most of the trawls were completed on earlier legs of the trip and on the state boats.  We have had opportunities, though, to observe and identify some of the fish from an earlier leg that had been put on ice.  We’ll come back to that process a bit later.

The first twenty-four hours underway were spent heading to our first station, off the southwest coast of Florida.  We have spent much of our time on this leg of the trip completing plankton collections.  My students should remember that plankton includes small and microscopic (too small to see with only your eyes) organisms. The organisms may be animals, plants and plant-like organisms, or bacteria.  The plankton found in the water can tell what the animal population looks like, or will look like if the conditions of the water do not change too much.  Plankton is also a source of food for certain animals, so looking at plankton can give us information about whether enough of a food source is present for those animals.  The purpose of the Bongo and Neuston tows is to collect plankton.  Before we do those tows at each station, however, we deploy the CTD to collect some important information.

Bringing in the CTD

A scientist and deckhand help bring in the CTD

Taking water samples from the CTD

The chief scientist, Kim Johnson, takes water samples from the CTD to verify it’s dissolved oxygen readings.

CTD stands for Conductivity, Temperature, and Depth.  The machine collects data in those areas, as well as other data.  The conductivity data tells how much salt (salinity) is in the water because the amount of salt affects how well the water will conduct (allow to pass through) electricity.  The CTD also measures the oxygen content of the water.  Remember learning about algae bloom in the Chesapeake Bay, and how the algae sucks up all of the oxygen, leaving the plants and animals in the area to die?  When a body of water has an unhealthy level of oxygen, it is called hypoxic.  Scientists are worried about the same kind of thing happening in the Gulf of Mexico, so determining the oxygen content in the water provides important information.  In the stations we have tested so far, the oxygen content has been healthy.  However, we have been far from land and much closer to where the Atlantic Ocean meets the Gulf.  To learn more about hypoxia in the Gulf of Mexico, visit NOAA’s hypoxia page.  Don’t forget to click on the links at the bottom that will take you to descriptions of the problems and causes of hypoxia in the Gulf.

After bringing the CTD back onto the deck, it is time to start a Neuston tow.  The Neuston net is very fine, and attaches to a one meter by two meter frame at the top.  The net gets narrower, and attaches to a “cod end”, a plastic cylinder with screened openings, at the bottom.  This is hoisted out of the boat and into the water by a crane.  It takes several people to launch the Neuston, as the frame is heavy, and it can be hard to manage in the wind.

Neuston net before deployment

The Neuston net is tied down to the boat until it is ready to be deployed.

The Neuston is pulled through the water, with about a foot above the surface, and the rest below.  The purpose is to collect plankton on or near the surface of the water.  Since sargassum, or seaweed, often floats on the surface of the water, sometimes the Neuston collects a lot of that.  We continue to tow the net for ten minutes, and then retrieve it into the boat, again using the crane.  While we did not do trawls and pull in large fish, we did see different kinds of baby fish at almost every station.

Neuston net

The Neuston net is dragged at the top of the water for five to ten minutes

The Bongo contains two 61 centimeter, circular, sturdy plastic frames, to which fine nets are attached.  These nets also narrow to a small area, to which cod ends are attached.  The Bongos are lowered off the port side by using the J frame. The bongos are towed from the surface to the bottom, but no deeper than 200 meters.  The bongo also has the flowmeters on it to calculate how much water passes through the net. The sample is used to estimate the populations, number, and location of animals in parts of the Gulf.  The Bongo also has instruments attached to it that measure temperature, salinity (salt), and depth.  In addition, the bongos have flowmeters attached to calculate how much water passes through the nets.

Bongo nets

The Bongo nets must be rinsed down before being brought into to boat to make sure no plankton is stuck at the top of the nets.

These are complicated tools, and some of the instruments are electronic.  If the instruments are not working correctly, the scientists and engineers must have a back-up plan.  In fact, at one station, the Bongo instruments were not giving accurate readings when the head of the watch (the scientist in charge) looked at the readings from inside.  The back-up plan was for the deckhands to use less accurate depth finding instruments when lowering the Bongo.  This can sometimes present a problem because if the instruments are off, and the Bongo drags on the bottom, a lot of mud can end up in the sample.  Fortunately, a little troubleshooting, in the form of tightening some connections, solved the problem.  Sometimes it’s easy to forget to check the obvious!

Once the Neuston and Bongo are up, we can detach the cod ends, and get to work preserving the plankton samples.  The plankton from the Neuston, and from each of the Bongo cod ends, are preserved and stored separately.  The Neuston and right Bongo plankton are rinsed through a very fine sieve with a chemical solution that is mostly ethanol, and then poured through a funnel into a jar, which is finally filled with the ethanol solution.  The left Bongo plankton is handled similarly, but instead of being stored in ethanol, it is stored in salt water from the Gulf, and a small amount of formalin.  Formalin contains a small amount of formaldehyde, and is used to preserve tissues.  It is a toxic chemical that is harmful to humans, and must be handled very carefully, always using gloves.  The samples are later sent to various laboratories to be sorted and counted.  In addition to providing information about amount and location of different species, scientists can also use the preserved plankton to determine the age, as specific as the number of days old, and genetics of the baby sea animal. The formalin helps preserve the otoliths a LOT better, where the ethanol helps preserve the tissue and/or DNA better.  The otolith is part of the inner ear of the animal and is the part that is used to determine age.

Work station at the stern of the boat

The work station at the stern of Oregon II is where we rinse the plankton and add the chemicals for preservation.

Rinsing the plankton

Sometimes we have to remove jellyfish from our samples. The plankton must be rinsed off the jellyfish before counting and discarding them.

With stations normally being about three hours apart, it would seem like we should have a lot of down time.  However, when there is a lot of sargassum in the Neuston, it must be rinsed to try to get the plankton out of it.  This can take quite a long time.  In addition, sometimes we do get small fish or other animals that need to be sorted, counted, measured and weighed.

Sargassum

There were over 300 of these file fish in one plankton sample. The color made them difficult to find in the sargassum.

A pipe fish from one of the Neuston samples.  What does it remind you of?

A pipe fish from one of the Neuston samples. What does it remind you of?

Plankton sample

This is a plankton sample from a Neuston tow after it has been preserved in ethanol.

Don’t forget to track our progress by visiting http://shiptracker.noaa.gov/shiptracker.html and choosing Oregon II.  While you are there, don’t forget to check out the different types of maps available for tracking Oregon II.  Look in the upper left-hand corner (Streets, Topo, Imagery, NOAA Nautical Charts, and Weather).

Personal Log

Settling in and enjoying the ride

The first three days of the trip had us motoring through incredibly calm waters and sunny days.  Some of the veteran crew members commented that they had never seen the Gulf so calm.  As we traveled further from Pascagoula, the water started getting bluer and bluer.  It is hard to describe the deep blue that we sailed through and the camera just doesn’t seem to capture it.  As we left the waters around Pascagoula, we saw many large ships, possible oil tankers, and quite a few oil rigs.  However, once we passed them, we’ve barely seen another boat.  It is something to look out from the bow of the boat and see nothing but water in every direction.

A calm day in the Gulf of Mexico

A calm day in the Gulf of Mexico

As promised, the food on board is delicious. The cooks take great pride in the food they serve, and there are always choices at every meal.  We’ve had beef tenderloin, veal parmesan, omelets, fresh fruit, fresh vegetables, pasta, Mexican, chocolate custard pie, cookies, pecan pie – all homemade!  The galley is also well-stocked with snacks.  Meals are served on a strict schedule – about an hour and a half for each meal.  However, if you know you will miss a meal, the cooks are happy to set some food aside for you, nicely wrapped in the refrigerator.  Luckily for me, I have the day shift, and if I miss a meal, it is normally breakfast.

Everyone on the ship has been very encouraging and helpful.  Some of the guys did a dive and brought me back some interesting shells to share with my students.  The other scientists have been incredibly patient and helpful.  Kim, the chief scientist, is a great teacher and is always looking for opportunities for me to learn something new, or practice something I just learned!

Did you know?

The starboard side of the ship is the right side, and the port side is the left side.  Starboard comes from the old Anglo-Saxon word, “steorbord” because the steering oar was on the right side of the boat.  Because of this, the ship would pull up to the dock, or port, on the left side. This would avoid damaging the steering oar.

Questions for my students:

What unit of measurement do you think we use to measure the small fish found in the Neuston and Bongo tows?

Can you think of any sea animals that use plankton as their main source of food?  It is okay to research this before you answer!

Thank you for visiting my blog.  I hope you will check back in a few days for an update!

4 responses to “Christina Peters: Finding Plankton on Oregon II, July 13, 2013

  1. I love reading your blog and find your descriptions fascinating. I especially like the photographs of the pipe fish! You are truly taking us with you knot of the way!

  2. I just love reading about your adventures and seeing the pictures. You are a true educator in and out of the class room. Thank you for the wealth of information. Keep it coming.

  3. answer from Ms. Peters student Aya:
    question #1: Are you using millimeters for measuring the small fish?
    question #2: The sea animals that use plankton as their source of food are: fish, whales, jelly fish.
    I love to read your blog, it’s very interesting. Thank you

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