Heather Haberman: Plankton, July 9, 2011 (post #3)


NOAA Teacher at Sea
Heather Haberman

Onboard NOAA Ship Oregon II
July 5 — 17, 2011


Mission:  Groundfish Survey
Geographical Location:  Northern Gulf of Mexico
Date:  Saturday, July 09, 2011

Weather Data from  NOAA Ship Tracker
Air Temperature:  30.4 C   (86.7 F)
Water Temperature: 29.6 C   (85.3 F)
Relative Humidity: 72%
Wind Speed: 6.69 knots   (7.7 mph)

Preface:  Scroll down the page if you would like to read my blog in chronological order.  If you have any questions leave them for me at the end of the post.

Science and Technology Log

Topic of the Day:  Plankton, the most important organisms on the planet.

Say the word plankton to a class full of students and most of them will probably think of a small one-eyed cartoon character.  In actuality plankton are some of the most important organisms on our planet.  Why would I so confidently make such a bold statement?  Because without plankton, we wouldn’t be here, nor would any other organism that requires oxygen for life’s processes.

Plankton are a vital part of the carbon and oxygen cycles.  They are excellent indicators of water quality and are the base of the marine food web, providing a source of food and energy for most of the ocean’s ecosystem’s.  Most plankton are categorized as either phytoplankton or zooplankton.

Question:  Can you identify which group of plankton are the plants and which are the animals based on the prefix’s?

Simple marine food web. Image: NOAA

Phyto comes from a Greek word meaning “plant” while planktos means “to wander”.  Phytoplankton are single-celled plants which are an essential component of the marine food web.  Plants are producers meaning they use light energy from the sun, and nutrients from their surroundings, to photosynthesize and grow rather than having to eat like animals, which are consumers.   Thus producers allow “new” energy to enter into an ecosystem which is passed on through a food chain.

Because phytoplankton photosynthesize, they also play an important role in regulating the amount of carbon dioxide in our atmosphere while providing oxygen for us to breathe.  Scientists believe that the oceans currently absorb between 30%-50% of the carbon dioxide that enters into our atmosphere.

Did you know:  It is estimated that marine plants, including phytoplankton, are responsible for 70-80% of the oxygen we have in our atmosphere.  Land plants are only responsible for 20-30%.

Diatoms are one of the most common forms of phytoplankton. Photo: NOAA

Question:  Since phytoplankton rely on sun and nutrients for their energy, where would you expect to find them in greater concentrations, near the coast or far out at sea?

Red and orange indicate high concentrations of phyoplankton. Concentrations decrease as you go down the color spectrum. Image from NASA's SeaWiFS mission

Notice the greatest concentration of phytoplankton occur near coastal areas.  This is because they rely on nutrients such as nitrogen and phosphorus for their survival.  These nutrients are transferred to the sea as rains wash them from our land into the rivers and the rivers empty the nutrients into the sea.  We’ll address the problems this is causing in my next blog.

Did you know:  The ocean is salty because over millions of years rains and rivers have washed over the rocks, which contain sodium chloride (salt), and carried it to the sea.

It is easy to identify water that’s rich in phytoplankton and nutrients because the water is green due to the chlorophyll pigment plankton contain.  The further away from the nutrient source you get, the bluer the water becomes because of the decrease in the phytoplankton population.

This tool is called a Forel/Ule scale. It is used to obtain an approximate measurement of surface water color. This helps researchers determine the abundance of life in the water.

Let’s go up a step in the marine food web and talk about zooplankton.  Zoo is Greek for animal.  Most zooplankton are grazers that depend on phytoplankton as a food source.  I’ve learned that larval marine life such as fish, invertebrates and crustaceans are classified as zooplankton until they start to get their adult coloration.  After hatching from their eggs marine larva are clear and “jelly like” which is an adaptation that helps them avoid being eaten by predators.  Camouflage is their only line of defense in this stage of development.

A zooplankton sample we collected aboard the Oregon II using a neuston net. Notice the small juvenile fish and all of the clear "jelly like" larva.

When plankton samples are collected two different methods are used.  One method uses a neuston net which skims the surface of the water for 10 minutes.  See the video below to watch a sample being collected.

I am securing the neuston net to the metal frame by lacing it with a line (rope for all of you land lovers)..

The second method is using the bongo nets which are deployed at a 45 degree angle until they are a meter shy of the ocean floor, then they are brought back up.  This method collects samples from the vertical water column rather than just the surface.  The samples we collect with the bongo net look much different from the samples we collect with the neuston net.  Bongo samples are filled with more larva and less juveniles.

Bongo nets getting ready to be lowered into the water column. They are called bongo nets because they resemble bongos. Photo: SEFSC

Plankton surveys are done in an effort to learn more about the abundance and location of the early life stages of fish and invertebrates.  All of the samples we collect are preserved at sea and are then sent to the Sea Fisheries Institute in Poland.  This is where all of the identification of fish larva and other zooplankton takes place.  This information is then used by researchers to study things such as environmental quality requirements for larva, mortality rates, population trends, development rates and larval diets.

On the right is the "cod end", or plankton collection chamber, which attaches to the end of the nets. We then sieve the contents of the cod end and funnel it into a jar along with some preservative.

Personal Log:

My last log mentioned bycatch as one of the bad things about bottom trawling.  Another problem associated with bottom trawling is the destruction of habitats as the net and “doors” sweep along the ocean floor.  So far we have had two nets tear as a result of this collection method.  It’s a good thing they keep ten extra nets onboard as back ups!

Here are some of the extra nets that are kept on deck.

Aside from the nets tearing off there has also been a problem with the wire that deploys the net.  It has been twisting which prevents the “doors” from opening the net wide enough for a good sample collection.  The crew has tried extending all of the wire off of the reel in an effort to untwist it.  It seems to be working well, but we still need to keep a close eye on it.

I have also had the opportunity to be the hottest I have ever been in my entire life.  We had an abandon ship drill where everyone had to get into their immersion suits.  Picture yourself in the Gulf of Mexico, standing on a black deck, in the middle of the day, in July, while putting on a full body jump suit made of neoprene.  Hopefully we won’t have to use them at any point during the cruise.

One Reply to “Heather Haberman: Plankton, July 9, 2011 (post #3)”

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