Arctic Science Journeys
Radio Script
2002

photo of larvacean
The larvacean Oikopleura labradoriensis produces a fragile mucus "house" to help it filter small particles from the water. (Photo courtesy of Per Flood.) Click on photo to see larger image.

Jello Plankton
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INTRO: Many of the more familiar creatures that live in the Arctic—animals like seals, bears, and birds—are made of fur, feathers and bone. But one species living in the frigid waters beneath the Arctic ice pack is made of a substance similar to Jello. For scientists who study this unusual animal, just catching them is often the hard part. Doug Schneider has more, in this week's Arctic Science Journeys Radio.

STORY: Russ Hopcroft is a marine scientist at the University of Alaska Fairbanks School of Fisheries and Ocean Sciences. He recently joined with some 50 researchers in a monthlong exploration of the Arctic Ocean above Canada and Alaska.

Few scientists have ever ventured into this largely unstudied region. This trip was possible only because researchers used a large ice-breaking ship to crunch their way deep into the ice pack. They went to learn as much as possible about how the high Arctic ecosystem works. For Russ Hopcroft, that meant studying the creatures that live beneath the ice.

HOPCROFT: "My area of expertise starts where the ice stops. I'm a zooplankton ecologist."

Zooplankton are tiny, shrimp-like crustaceans. They eat algae and other marine plants, and are themselves prey to fish, whales and other large predators. There are many species of zoolankton. But to Hopcroft, none are more interesting than those made of gelatin.

HOPCROFT: "My interest up there is in looking at the more fragile gelatinous zooplankton that haven't been studied well in the Arctic. Most of the crustaceans have a consistency like that of an insect or an animal. They have an internal or external skeleton. Gelatinous zooplankton are those animals that have tissues that are much more watery. A jellyfish is a classic example."

photo of larvacean
This is an example of a ctenophore, Bathocyroe fosteri, which is a mesopelagic species. (Photo courtesy of Marsh Youngbluth). Click on photo to see larger image.

Since gelatinous zooplankton lack a hard skeleton, catching them intact is next to impossible. All too often, they're smashed and smeared in nets used to capture them. Hopcroft likens it to pushing Jello through a strainer.

HOPCROFT: "Because people like to get a lot of material out of a plankton net, a lot of people tow them fairly fast through the water. And what that means is that anything with a soft body gets extruded—just like Jello through a mesh. It also means that animals that don't get extruded end up distorted and messed up and they're not recognizable. It's hard to appreciate how the animal operates when you just have pieces of them."

To avoid obliterating these tender-tissued animals, Hopcroft designed a specialized trap. When connected to a remotely operated vehicle (ROV), the idea is to catch them intact and unharmed.

HOPCROFT: "One of the things we've been working on since the program was funded was taking a basic ROV and outfitting it with the tools required to collect these animals in the mid-water. So we have the ability on this vehicle to go down with a kind of slurp gun or vacuum cleaner and suck up fairly gently these animals. And then we have traps that are a tube with two doors. So we can lower the sampler over the animal and close the doors. Typically the animal doesn't know anything has happened to it until it bumps the sides or the doors."

So why all the fuss over zooplankton? Well, scientists want to know more about just how the under-ice ecosystem works. Plankton form the base of the region's food chain. So ultimately, nearly every species, such as whales, seals and even humans who gather their food from the sea, depend on healthy plankton populations. Learning how the ecosystem works is especially critical now, since there's plenty of signs that the Arctic is changing.

HOPCROFT: "Some predictions for the Arctic are that in 50 years there won't be any permanent ice cover. It will be a seasonal ice cover. Now if that happens, the way the ecosystem operates will change profoundly—in ways that we can't even anticipate because there are so many factors that will come into play. So it's important for us to see how the system operates now, to some degree for posterity, but also for us to be able to look back to see how and why it has changed."

OUTRO: Thanks this week go to the National Oceanic and Atmospheric Administration's Ocean Exploration program. This is Arctic Science Journeys Radio, a production of the Alaska Sea Grant Program at the University of Alaska Fairbanks School of Fisheries and Ocean Sciences. I'm Doug Schneider.


Audio version and related websites

Thanks to the following individual for help preparing this script:

Russell Hopcroft, Assistant Professor
University of Alaska Fairbanks
School of Fisheries and Ocean Sciences
Institute of Marine Science
Fairbanks, AK 99775-7220
Email: hopcroft@ims.uaf.edu
Phone (907) 474-7842


Arctic Science Journeys is a radio service highlighting science, culture, and the environment of the circumpolar north. Produced by the Alaska Sea Grant College Program and the University of Alaska Fairbanks.

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Related Web sites

Russ Hopcroft: Faculty Profile

NOAA Ocean Explorer: Canadian Basin Exploration

NOAA Ocean Explorer Home Page

NOAA Ocean Explorer: Spineless Wonders