Water Fleas

Podcast

Water Fleas

Transcript

The Great Lakes are invaded - again. I'm Bob Hirshon and this is Science Update.

A tiny flea could be spelling big trouble for the Great Lakes. That's according to Hugh MacIssac. He's an aquatic ecologist at the Great Lakes Institute for Environmental Research. Dr. MacIssac was warned of the flea while attending a conference in Ireland. When he got back to the states, he found that the warning had been a timely one.

MacIssac:
"I came home and there was a message waiting for me that there was a problem identified in Lake Ontario."

The tiny fleas clump together and create a jelly-like mass around their bodies. Aside from being gross, the fleas can clog up fishing lines and nets. And their voracious appetites for plankton could starve out small feeder fish.

MacIssac:
"The smaller individuals would face what we call a bottleneck and //eventually of course, you would have no larger fish in the lake."

Dr. MacIssac says that the flea must've arrived on an ocean liner that docked in the lakes. So far, the flea hasn't managed to spread across all the Great Lakes. But like another invader, the zebra mussel,the flea reproduces very quickly and is hard to kill.

Dr. MacIssac says that what's at stake is the Great Lake's multibillion-dollar fishing industry. And already, sport fishermen have begun avoiding parts of the Great Lakes because of the flea.

For the American Association for the Advancement of Science, I'm Bob Hirshon.

Making Sense of the Research

You may think that alien invasions are the stuff of science fiction movies. But invasions of alien species are very real, and can be very dangerous. Some invasions are merely nuisances, but others can cause the extinction of native species, and the disruption of local industries. As you just learned, in the Great Lakes an Asian species of water flea has been discovered. It reproduces quickly, and the result may be fewer game fish, and enormous loss of revenue from the fishing industry.

You can use this Science Update as a starting point for a discussion of ecosystems, and how the parts of a system interrelate. It is also a good case study on the disastrous and unforeseen consequences of what might seem like a trivial environmental mistake-- the release of a little foreign bilge water from a ship.

Now try to answer the following questions:

1. What is meant by the term "alien species"?
2. What impact has the introduction of the Asian species of water flea had on the Great Lakes?
3. What is the potential impact for the entire ecosystem? Describe how each part of the system might be affected by this invasion.
4. How do scientists think that this organism was introduced into the Great Lakes ecosystem?
5. Can you think of another example in which the introduction of a foreign species led to disastrous consequences?
6. Can you think of a time when an alien species was deliberately introduced into an ecosystem? For what purpose? What was the result?

Going Further

For an online investigative unit related to this topic, go to NOAA Research, from the National Oceanic and Atmospheric Administration's Office of Oceanic and Atmospheric Research (OAR). This unit investigates the impact of a foreign species on the Great Lakes region and develops strategies for the restoration of this ecosystem.

Begin by reading the overview of the Great Lakes unit. Then read Zebra Mussels to learn more about how the invasion of a foreign species of mussel impacted the Great Lakes ecosystem. Compare this event to the current issue of the Asian water flea.

You could try one or more of the activities in the Application section, using what you've learned to develop a plan for the restoration of the Great Lakes' ecosystem.

This site also offers links to sites with additional information on lake ecosystems and the impact of foreign species on ecosystems.