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5 June, 2000

The MocNess Monsters

June 5, Monday

How do you catch monsters at sea? With a monster net, of course!

The "monsters" that marine biologist Peter Lane is interested in catching are actually tiny animals called zooplankton. Zooplankton live in oceans all over the world and are an important source of food for fish, whales, and other marine mammals. They are some of the most abundant animals in the world. Although they don't look very impressive to the naked eye, when viewed under a microscope, they look a lot like monsters from the deep!

Today Janice and I helped Peter catch the little critters with a piece of equipment called the MOCNESS. MOCNESS is actually an acronym that stands for "Multiple Opening and Closing Nets and Environmental Sampling System. Nine nets hang off a metal frame that is lowered into the water and towed behind the ship.

Peter is interested in finding out what kinds of zooplankton are here in the Davis Strait. He also wants to know how many there are, and where they are. >From previous MOCNESS experiments, scientists have already learned that the zooplankton like to hang out together in large groups wherever they find phytoplankton (microscopic plants) to eat. They also know that zooplankton usually rise up to the surface at night to feed and lay their eggs. During the day, they go deep in the ocean where they can hide from birds and other predators.

It took Peter several days to get the MOCNESS ready to go. When it was time to conduct the experiment, the nets were lowered into the water with a winch. Computerized sensors attached to the frame told Peter how deep the MOCNESS is in the water. Each net can be opened and closed at different times. Peter can decide when to open and close the nets.

For this experiment, the MOCNESS was lowered 500 meters down into the water. Peter opened the first net at the bottom and waited as the winch raised the MOCNESS up. When it reached 400 meters, Peter sent a signal to sensor that closed that net. That way, he could catch zooplankton that were hanging out in the water at depths between 400 and 500 meters. He continued this process as the MOCNESS was slowly raised to the surface.

When the MOCNESS was finally lifted back onto the Healy, I helped Peter wash out the nets into special buckets called "cod ends" that are attached to the end of each net. Then we removed the cod end from the net so we could see what we had caught. The water in the cod ends looked like pea soup, only it was pink instead of green! We had caught thousands of zooplankton called copepods. They looked like miniature shrimp. There were other critters, too.

We helped Peter pack the cod ends into crates and carry them into the laboratory where we could look at them under the microscope. To see pictures of the "MOCNESS Monsters, click on Janice's page:

Janice's Entry Today.

DAILY DATA LOG (6/05/00)

Air Temperature: 2 degrees C / 36 degrees F

Clear skies, sunny

Latitude 57N

Longitude 55W

Sunrise 5:04

Sunset 10:33

Actually, it never got DARK last night. For an hour or two in the middle of the night, it was more like dusk than night. But even at midnight you could see light on the horizon.


These instruments tell Peter how deep the nets are in the water.


Peter has the frame ready for the nets to be attached.


Marine Science Technician Glen pays out wire at a speed that Peter determines.


Water in the cod end is teeming with life.


Peter checks the monitors while MOCNESS is collecting samples.



The MOCNESS is sampling in ARCTIC waters.


I am helping Peter to rinse out the nets. He wants all the samples in the cod ends at the bottom of the net.


Peter with his zooplankton "catch"


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