A crew of young Yukoners is spending the summer kicking over rocks in streams and collecting the little wriggly things that crawl and float out from underneath -- all in the name of science.

The young people, part of the Yukon Youth Conservation Corps (Y2C2), are helping Benoit Godin of Environment Canada gather baseline information onYukon streams.

They're doing a great job, says Godin, head of the department's Environmental Contaminants section in Whitehorse.

"Actually, they're so keen they do overtime," he says, pointing out a stream sample recorded late on a June evening, well after the crew's nominal quitting time.

Godin had a Y2C2 crew for a few weeks last summer, and they collected data from 51 creeks in the southern and central Yukon. This year's crew will work on the project a little longer.

"We've sampled 30 creeks so far," he says. "We might get 90 creeks this year."

The only major disadvantage to using the Y2C2 crews, Godin says, is that he doesn't get to do the fieldwork himself.

"I would like to do it, but they're more efficient than we are. There's a crew leader and four members. They can hit a creek, wrap things up in 45 minutes, and move on."

Crew members record basic information about each sampling site, including location, time, slope, and vegetation. They take stream flow measurements and basic water quality measurements, such as temperature, acidity levels, conductivity, and dissolved oxygen readings.

Then they collect samples of the sediment, algae, and benthic invertebrates, the little creatures that live in and on the stream bottom. The sediment samples will help expand a national information base about the nature of Canadian streams.

The algae samples provide information about water quality, Godin says. Algae are particularly sensitive to arsenic, he explains, and there is a lot of natually occurring arsenic in Yukon rocks and soils. It's important to know what kinds of algae are present in different types of Yukon waters because any change in the mix of algae might indicate a change in water quality.

The best part of the process is collecting the benthic invertebrates, says Godin.

"They're using a kick net. You collect everything that you can turn up within three minutes by walking along a 10-metre stretch of the creek while kicking the rocks," he explains. "It's a very vigorous kicking that dislodges all the insects. It's fun."

A random selection of 200 bugs is sorted and preserved from each site. Later, as money is available, they and the algae samples will be identified by experts.

The kind and mix of benthic invertebrates in a stream provide vital information about the health of the aquatic environment. The disappearance of a species or the sudden growth in numbers of a species can serve as an early warning that something has happened to the stream. The collection of chemical characteristics helps identify the stream's biological responses to chemical changes.

The Y2C2 crews' collections, gathered over two summers, are also adding significantly to the general knowledge of Yukon insects, says Godin.

"We've built up the master list of Yukon insects quite a bit," he says. "I was looking at a recent book on insects of the Yukon and saw one species that had been reported only once, near Kluane. Then I looked at my database and saw that we had found it all over the place."

Once the results from this year's sampling are added to the 51 sites sampled by last year's Y2C2 crew, the database will provide useful information about the nature of Yukon streams, says Godin.

The goal is to get enough information to be able to say what is normal and what is not, he says.

For more information about stream sampling, contact Benoit Godin, Environment Canada, at 667-3402. For information about the Y2C2 program, contact Yukon Renewable Resources.