Oregon Sea Grant

"What are those bright green plants?" Teri Grimm asked herself while fly fishing in central Oregon's popular East Lake. She collected a sample of the unusual plant and took it to Sam Chan, Oregon Sea Grant Extension's specialist in aquatic invasive species. Chan confirmed that Grimm had found an invader: Eurasian Watermilfoil, an aquarium plant that can crowd out native vegetation, block irrigation channels, and impede boat navigation when it finds its way into lakes and streams.

At the time, Chan was completing a field guide intended for people just like her. On the Lookout for Aquatic Invaders: An Identification Guide for the Pacific Northwest is a compact, spiral-bound field guide, sized to fit in a backpack, that displays basic information, full-color photos, and key identification characteristics of many aquatic invaders already established or likely to become established in the Pacific Northwest. Aimed at watershed councils, resource managers, and community groups, it's become a Sea Grant best seller since its publication in 2008.

"I own several copies and have given some to my friends," said Grimm, who has ordered copies of the guide for members of the Central Oregon Flyfishers, a club that promotes the preservation and conservation of central Oregon's watersheds. "I keep one in my car. It is not highly technical, and a layperson can use it to identify some plants."

Invaders spread easily

Invasive species can spread when they hitch a ride on humans - stuck to their clothing or wedged in their boot treads - and in pumps and water used for fire suppression. So Amy Rusk, a hydrologist for the Umpqua National Forest, plans to brief U.S. Forest Service fire crews on aquatic invasive species at the start of each fire season. Several crew leaders already have their own copies of the Sea Grant field guide, so they can learn to keep themselves free of pests and reduce the spread between National Forests.

"The guide is user friendly," said Rusk. "It's not too over-scientific for the fire crews who may not have a background in biology."

Rusk herself discovered a brown, slimy gunk growing in a stream, while she was investigating designated fish habitats. She was familiar with the field guide photos of the invasive algae Didymo, also known as rock snot, and remembered the description of the texture as "damp wool."

Learn more

• Read the whole story: printable .pdf | plain text
• Learn more about Oregon Sea Grant's work on aquatic invasive species