Zoop Soup!

RUCOOL is working with the Virginia Inst of Marine Sciences on our National Science Foundation (NSF) Long Term Ecosystem Research (LTER) project in Antarctica.

Who: The zooplankton team/members of Virginia Institute of Marine Science’s Steinberg lab

What: The zooplankton team has begun to conduct MOCNESS tows

When: December 2, 2021

Where: The more southern part of ocean next to the Western Antarctic Peninsula

Why: We perform MOCNESS tows to collect zooplankton from different depths. This lets us see how animals change as depth changes!

Finally!! We were able to put the “MOCNESS” in the water! “MOCNESS” is not a sea monster! It stands for “Multiple Opening Closing Net and Environmental Sensing System.” It’s not as complicated as it sounds. It is basically nine nets in one. We send all the nets down at once and then slowly bring the net up. As it comes up, we open one net, collect the animals that are there, and then close the net. Then we open the next net and repeat the process. This lets us see what animals live at different depths. The MOCNESS collects animals as deep as 1000m and as shallow as 50m!

Now what are these animals we are collecting? They are “zooplankton”! “Zooplankton” are any animal that cannot swim against the ocean currents. This can describe jellyfish, krill (shrimp-like animals), or larval (young) animals like crab and lobster. Zooplankton are everywhere and can come in all different shapes and sizes! In Antarctica the most common animals we catch are krill, copepods (think plankton from Spongebob!), chaetognaths (worms), and pteropods (snails). These animals are typically found shallow in the water column, so we can catch them in our simpler “Metro nets.” Metro nets are single nets that stay open all the time. We send them down to shallower depths and they collect the zooplankton they encounter.

So, now you know why the MOCNESS tows are special – we get to go deeper and we know where the animal came from! Another bonus is that we see animals that would never show up in our simpler nets because they live in deeper waters. For example, in our MOCNESS tows we may see a lot of red and black amphipods (bugs), big jellyfish, and sea spiders!

After we conduct Metro tows or a MOCNESS tow, we work as a team to identify, count, and measure the volume of every animal. We may also conduct experiments on the live animals!. One is a “fecal pellet production experiment” – essentially watching and waiting for the animals to poop! We place the animal in a bucket full of seawater, leave it for a few hours, and then collect its poop. We want to learn more about the carbon and nitrogen that goes to the bottom of the ocean when these animals poop! Our other experiment involves larval (or young) fishes. In this experiment we want to measure their “thermal tolerance,” or what is the hottest temperature they can survive at. The fishes in these experiments are typically not found in other parts of the world!

About the Authors: Maya Thomas and Tor Mowatt-Larssen are graduate students at the Virginia Institute of Marine Science and Meredith Nolan is a senior at the College of William & Mary. This is all their first time to Antarctica!

Images: a. The zooplankton team admiring the Antarctic scenery before a net tow. (Left to Right: Maya Thomas, Meredith Nolan, Tor Mowatt-Larssen).  b. A Metro net coming out of the water with all the zooplankton that it has collected.  c. Maya Thomas with a large jellyfish from a Metro tow. These are rare to find in our nets!  d. An example of what a Metro net collects. The large, orange animals that look like shrimp are Antarctic krill!