1 Aug 2012

CCE LTER Cruise: Day 3, Releasing the MOCNESS

Posted by dlebental

Written by Dana Lebental, Teacher at Sea

July 30- Day 3

Late last night we attempted to release the MOCNESS. No, this isn’t a long-necked sea monster but rather a piece of equipment used to capture zooplankton, some of the tiniest animals in the ocean. MOCNESS stands for Multiple Opening and Closing Net and Environmental Sensing System. It consists of 10 separate nets that go out simultaneously. Each net opens and closes at a different depth with only one net being open at a time. The CCE researchers will look at how many, what types and what kinds of zooplankton species are at the different depths ranging from 0 ft to 1500 ft. At its deepest, the MOCNESS will be lowered about a quarter mile deep (~1500 ft) into the Pacific Ocean.

The Multiple Opening and Closing Net and Environmental Sensing Systems

The Multiple Opening and Closing Net and Environmental Sensing Systems

We drag the net next to the boat, and the plankton get funneled down the “tentacles” to the cod-end. This consists of ten nets that are computer operated to open and close at different depths. The trick is to straighten the nets out so everything works correctly. Sometimes its easier said then done.

The zooplankton that is caught in the net is counted and classified so they can study what types of zooplanton are found at different depths. Different types of zooplankton include krill (euthausiids), copepods (look like Plankton, from Spongebob) and jellyfish.



Zooplankton caught in the first tow of the MOCNESS


Many animals participate in a vertical migration. What that means is during the day, many animals such as krill will try to go deeper in the water to avoid predators such as blue whales, sardines and other animals that find food with their eyes. By going deeper in the water, there is less light, so they can hopefully avoid being eaten. At night they go back to the surface of the water, where there is smaller zooplankton or phytoplankton (tiny plants in the water) that they can eat for food.

Cat and Jenni are experts at deploying and retrieving the MOCNESS. Jenni is a year one PhD student and Cat is a year two PhD student both at Scripps Institution of Oceanography working with Dr. Mark Ohman. Together they work to help gather information on the types of zooplankton living at different depths of the ocean.

Jenni and Cat

Setting up the MOCNESS to collect zooplankton in the Pacific Ocean.





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2 Responses to “CCE LTER Cruise: Day 3, Releasing the MOCNESS”

  1. […] samples had to be done at night so we could ensure that the zooplankton was present at the sampling depth (remember they migrate up and down in the water column). So […]