Multi-coring

Ms. Callaghan’s Classroom

Jil Callaghan is a 6th grade science teacher at Houck Middle School in Salem, Oregon. She is posting blogs for her students while aboard the Research Vessel Sikuliaq as part of a teacher at sea program through Oregon State University. 


Getting to the Bottom of What’s Happening in the Arctic Ocean

Yesterday we did our first deployment of a piece of science equipment that is called a multi-corer.  I got to help out and had fun! First you have to wear what’s called a big orange “float coat” that will help you stay afloat if you go overboard, but it also helps keep you warm 🙂 You also have to put on a hard hat. In the photo above, I got to help pull the multi-corer back towards the ship – we use hooks to attach ropes to loops on the multi-corer.

Jil on steel beach.jpg
While we were waiting outside in the below-freezing cold for the multi-corer to be ready, I took advantage of the warm deck.  The deck floor is heated to prevent any ice from forming – they call it the “steel beach”.

What’s a multi-corer?

A multi-core is a piece of scientific equipment that we send down to the bottom of the ocean where it drives 4 tubes into the sediment layers down there.  As we lift it up, it snaps shut, giving us tubes with “cores” of the sediment (mud) at the bottom of the sea.  It also has a CTD tube to collect water, measure temperature, and salinity; an altimeter to measure pressure and depth; as well as a very expensive curved lens for the camera; and 2 lasers.

multi-corer.jpg
The multi-corer is strapped down to the deck while we move to the next location where we’ll take samples.
Jil before deployment.jpg
The operations of the Sikuliaq depend heavily on a well-trained crew to operate all the machinery and assist with data collection. (I’m on the far right)

What does the mud tell us?

Dr. Miguel Goñi from OSU is looking for evidence of animals and plants that have died and fallen to the ocean floor.  Looking at what is on the ocean floor gives us an idea of what has been growing and living in the water up above. Based on the rate at which sediment falls to the bottom, and the depth of the samples we collect (some of that mud down there is very thick, like clay, and hard to push through), our samples can tell us what’s been happening for the last 200 years!

One thing that we can see evidence of is phytoplankton blooms – where the ocean currents bring nutrients (food) and the phytoplankton (microscopic marine plants) suddenly grow like crazy – called a “bloom”.  After they use up the nutrients they die, and some will fall down all the way to the bottom of the ocean (others will be eaten before they reach the bottom). This layer of dead phytoplankton as evidence of blooms is one of the things that Dr. Goñi is looking for in his core samples.

cutting a core.jpg
Dr. Miguel Goñi of OSU cutting a core sample.  The cores are cut into layers 1 cm thick by placing a 1 cm tall plastic ring on top before we push the mud up.  We cut between the plastic ring and the tube.
mud core up close.jpg
We found all kinds of critters in the mud, including  benthic amphipods (#19 in the illustration below), isopods (17), scaleworms (15), tube worms (not shown in the illustration), as well as brittle stars (12) on the surface layer.
3-Benthic_animals-(D)-Various_benthic_animals--(copyright-Kristin_L_V).jpg
Types of organisms that can be found on the ocean floor. Illustration: Kristín Líf Valtysdótti

The above illustration shows various benthic animals: 1. common whelk, 2. blue mussel, 3. Neptune whelk, 4. periwinkle, 5. Yoldia hyperborea, 6. sand gaper, 7. limpet, 8. scallop, 9. chiton, 10. common starfish, 11. green sea urchin, 12. brittlestar, 13. ragworm, 14. pectinaria worm, 15. scaleworm, 16. skeleton shrimp, 17. isopod, 18. barnacle, 19. benthic amphipod.

coring 1.jpg
It was so cool to watch pieces of ice float by as we were working on deck!  I’m standing next to the hose because we wash off the utensils (the metal sheet for cutting, the spatula used for scraping it into the bag, and the plastic ring) in between samples so that we don’t contaminate one layer with mud from another!
coring-in-process
After we cut a 1 cm sample, we put that sample into a plastic bag that has been carefully labeled.
Mud bags labeled.jpg
For each sample, we make sure that we know which cruise it was, where it was taken from, and how deep down from the surface the sediment is from.  The sediment samples will be analyzed back in Dr. Goñi’s lab at OSU.

See Ms. Callaghan’s other posts here.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s