Roy Moffitt: Bring in the Bongos, August 16, 2018


NOAA Teacher at Sea

Roy Moffitt

Aboard USCGC Healy

August 7 – 25, 2018

 

Mission: Healy 1801 –  Arctic Distributed Biological Observatory

Geographic Area: Arctic Ocean (Bering Sea, Chukchi Sea, Beaufort Sea)

Date: August 16, 2018

 

Current location/conditions:

Evening August 16 – Due west of Barrow, Alaska within sight of the coast

Air temp 35F, sea depth  40m , surface sea water temp 41

 

Bring in the Bongos

Bongo Nets ready for deployment

Bongo Nets ready for deployment

In a previous blog I showed the Methot net that catches very small (1-5cm) fish. However, if we want to catch sea life even smaller, we bring in something called a “bongo net.”  The bongo nets have very small openings–the larger nets are 500 micron (1/2 a millimeter) and the smaller nets are 150 micron.   In the picture below, you will see the back tail fin of the Healy with the bongo nets suspended from the hydraulic A-frame.  The A-frame supports a system of pulleys that are used to deploy and retrieve equipment (such as nets and moorings).

 

 

 

 

bongo canister

Organisms caught in the bongo net are washed down into this canister attached at the end.

The net looks and feels more like a tough nylon fabric, however, the water freely flows through the opening trapping the tiny organisms of the sea.  These organisms are pushed into the canister at the end of the net as shown in the picture on the right. While most of them are pushed into the canisters, many are stuck on the side of the net in a sticky goop.   The gelatin like goop is sprayed off the net with seawater by using a hose.  The process takes just a few minutes. Since I was the net holder and stretcher I got little wet!

 

 

Copepods in a Jar

Copepods in a Jar

The main organisms that we caught today were copepods. They are shown in the jar appearing pink.  Copepods are small crustaceans only 1-2mm in size that drift in the sea and feed on phytoplankton. Copepods are an important bottom of the food chain member of the ecosystem and serve as prey for fish, whales, and seabirds.

 

 

 

Flowmeter

Flowmeter suspended at the top of a bongo net

On the front of each net there is a flow meter as shown in the picture. It looks like a little torpedo with a propeller.  When the net trawls behind the ship, water flows through the net.  The amount of water that passes through the net can be calculated.  Using this calculation and the amount of organisms in the net, scientists can calculate the density of living microorganisms at a certain heights in the water column.  With annual samples scientists will be able to determine any changes over time including changes to the overall health of the regional ecosystem.  Today’s samples will also be sent out to a lab for further analysis.

 

Today’s Wildlife Sightings

Today I had unique experience– listening to wildlife.  This was a highlight.  Marine mammal acoustic scientists, Katherine Berchok and Stephanie Grassia, released an acoustic buoy this afternoon.  On top of the ship they put up an antennae and listened in for whales and walrus.  They were able to hear the constant underwater chatter between walruses.   As I wore the headphones and listened in, I was in awe at the grumbles and the ping sounds the animals were making back and forth underwater.  While we don’t know what the walrus were communicating back and forth to each other, to eavesdrop on these conversations, miles away, in real-time, was a pretty special experience.

 

Now and Looking forward

We did not see any ice today. I am looking forward to getting out of the fog and rain and returning back to the ice in the coming days.

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