Very Small but Very Important

Sept. 14, 2018

Despite Hurricane Florence’s destruction on the Carolina coasts, the FSV Henry B. Bigelow has kept sampling stations at a steady pace.  We are currently outside Long Island, well out of the reach of the hurricane’s wind and rain.  As of now, it’s all clear for us to keep sampling stations and working up fish, but fish aren’t the only thing we’re catching in nets.

The ocean is amazingly diverse.  There are well known animals such as tuna, cod, and whales.  They could be valued for recreational enjoyment, commercial importance or intrinsic pleasure.  And there are numerous animals such as starfish, sea urchins, jellyfish, corals, and sponges that are only found in the ocean.  But there are hundreds of easily overlooked, very small yet vitally important species that benefit all living creatures, aquatic and terrestrial: plankton.

Simply put, plankton are very small, sometimes microscopic animals (zooplankton) and plants (phytoplankton) that drift in the water.  Found in both fresh and salt water, they are the base of the aquatic food web.  Not just that, but phytoplankton produce about half of Earth’s oxygen!  Because of their crucial environmental role, it is extremely important to study and monitor these fascinating organisms, and we have a protocol for doing just that on the bottom trawl surveys.

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Bongo nets. Photo credit: NOAA Fisheries/Christine Kircun

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Survey Technician Mark Bradley spraying the contents of a plankton net into a sieve. Photo credit: NOAA Fisheries/Christine Kircun

Plankton tows are cast at select stations on the FSV Henry B. Bigelow.  This is called a ‘bongo’ because the two nets used look like bongos.  The bongo is lowered over the sidesampling station to about 5-10m from the bottom, depending on the ground type and weather conditions.  As soon as it reaches its appropriate depth, it’s brought back to the surface.  This gives us a vertical profile of the organisms in that area.The nets are washed down into a sieve, and the plankton are preserved with formalin in glass jars which will be examined back on land after the survey is completed.

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Jar filled with plankton. Photo credit: NOAA Fisheries/Christine Kircun

Before the jars are preserved, a quick, first glance may leave the observer uninterested.  But simply wait a moment, and the jar comes to life!  Depending on the sampling location and time of year, ostracods, copepods, protozoans, jellyfish, mysids…. can be seen moving and zooming all over.  So the next time you’re enjoying the beach and gazing out on the water, know that it is far from empty!  You are actually watching thousands and thousands of plankton, working hard to support life in the ocean and on land.  So take a deep breath and say “Thank you!”

Plankton studies is not my area of focus, but it is for the people in the NEFSC Oceans and Climate Branch!  Check out their website at Oceans and Climate Branch for more information.

Christine Kircun
Aboard the FSV Henry B. Bigelow
Fall 2018 Bottom Trawl Survey Leg 1

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