Did you know there are shrews that spend much of their lives underwater, scrabbling along the bottoms of creeks in pursuit of insect prey and small fish?

Doug Davidge didn't know about Water Shrews -- not until one of them passed in front of an underwater camera he left overnight in McIntyre Creek near Whitehorse.

Davidge, a technician with Environment Canada, wasn't looking for shrews. He was hoping to add to a huge database of information about the Yukon's benthic invertebrates, the small insects and insect-like creatures that live on and in the beds of Yukon streams. Finding a benthic mammal like the little shrew was an unexpected bonus.

The term "benthic" refers to the bottom of water bodies. It's an area full of life. The bottom-most layer of water, and the rocks and sediments beneath it, are home to a multitude of plants and animals, ranging in size from the shrew and small fish to life forms consisting of a single cell.

It's also the best place to measure the health of a stream. The water itself keeps moving, but the sediments, the metals, the chemicals, and the other things it carries settle out into the bottom sediments. There they can have a profound impact on benthic creatures.

Davidge and Environment Canada biologist Benoit Godin have been collecting and organizing information on the Yukon's benthic environment for years. They now have a database with information about 1420 sampling sites, identified by longitude, latitude, and date. And they're not done yet.

"We have a herd of samples yet to be counted from this past year," said Godin.

Since the 1970s, benthic invertebrates have been collected as part of environmental impact assessments of projects like mines or sewage treatment facilities. Accompanying the samples was information about stream chemistry, sediment composition, plants, algae, and all the things that make up the benthic world.

Godin and Davidge began pulling the scattered bits of information together and realized that they had a potentially useful record of the health of the Yukon's water bodies. However, it was spotty, with clusters of sample sites in the areas where development had been proposed.

Several years ago, they started to fill in the gaps. They looked up the original data quoted in reports and added that information to their growing database.

"Mining companies and consultants working for mining companies contributed a lot of the data," said Davidge.

"That's very important," Godin added. "Their data was getting lost, and now it will be available."

More of the gaps were filled in by a succession of summer student crews from the Yukon Youth Conservation Corps (Y2C2). Starting in 1997, they collected samples, observations, and photographs from streams along virtually every road in the Yukon.

"We told them, just hit the road and, at every creek you spot, do a sample," Godin said.

After combining all their sources, Davidge estimates that the benthic database contains between 90 and 100 per cent of all existing data about benthic invertebrates in the Yukon.

That information includes 31,000 separate sample counts totaling about 2.2 million individual creatures from 664 different taxa (broad groupings of related creatures), plus tens of thousands of records of things like sediments, plants and algae, water chemistry, stream flow, and stream character.

"We're just about to enter the analysis stage now," said Godin. He hopes that university researchers will use the data to learn more about the benthic world. He also hopes that industry will find the database useful when preparing environmental assessments and planning development.

For more information about the benthic database, contact Environment Canada, Yukon Region, at (867) 667-3400.