Invaders From the Deep
Emerging from the murky confines of the world’s waterways, an insidious problem is oozing into Oregon. Non-native plant and animal species are invading Oregon’s waters and successfully establishing with help from unwitting accomplices
—humans.
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European green crabs are voracious predators of native shellfish and crustaceans. Photo: OSU Hatfield Marine Science Center |
Most invasions are accidents, but they are costly. In Oregon, millions of dollars are spent on surveillance alone because, once established, invasive species are all but impossible to eradicate. Sam Chan is one of the few vigilant guards patrolling Oregon’s waterways. As an OSU Extension aquatic ecosystem educator and chair of the Oregon Invasive Species Council, Chan battles noxious knotweed, masses of mudsnails, and a growing green crab threat. Unfortunately, he and the handful of colleagues working on invasive species around the state are too few to conquer the increasing onslaught. Chan’s battle plan therefore is simple: educate the public to serve as deputy watchdogs throughout the state.
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Zebra mussels, introduced from Eurasia in ballast water, could clog pipes and dam turbines if the species becomes established in Oregon waters. Photo: OSU Hatfield Marine Science Center |
There are many ways to introduce an invasive species. Knotweed, for example, was introduced intentionally for its beauty. Others, such as parrot’s feather, were introduced accidently through the aquarium trade. Eurasian milfoil, another aquarium exotic, can become thick enough during low flows to stop kayakers in their tracks. Many aquatic invasive animal species hitchhike onboard ships, entering Oregon in ballast water. Invasive aquatic species can be difficult to locate in open water and problematic to eradicate without harming the rest of the ecosystem. And, there’s often no way to know whether a species will become established as an invader—until it’s too late.
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A population explosion of invasive Tui chub in Diamond Lake forced managers to treat the lake with the pesticide rotonone in 2006. Photo: Jim Craven, Mail Tribune |
For example, the Tui chub, a two-inch minnow species, changed the ecosystem of Diamond Lake. Located in the southern Cascade Mountains, Diamond Lake has one of Oregon’s successful manmade trout fisheries. While the introduced trout never proved to be invasive, the Tui chub did. Used as live bait, the chubs that got away proved enormously resilient. As the minnow multiplied, so did the number of algal blooms. The Tui chubs feasted on the zooplankton population, the species who live on algae and keep their numbers in check. Without zooplankton, the blue-green algae grew out of control, occasionally creating toxic blooms. Diamond Lake was partially drained in 2006 and treated with the poison rotenone to kill millions of pounds of Tui chub, before restocking the lake with trout.
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OSU's Sam Chan enlists the help of Oregonians to battle invasive species that threaten Oregon's water. Photo: Bob Rost |
“It’s simply a lack of awareness that creates pathways for introducing species,” Chan said. He and colleagues from the U.S. Coast Guard, the Environmental Protection Agency, Portland State University, and OSU are raising awareness about several organisms that threaten invasion in Oregon. They include the zebra mussel, which could cost tens of millions of dollars annually to clean out if it were to become established and clog dam turbines along the Columbia River; and the green crab, an aggressive predator that multiplies quickly, which could impact the oyster and crab industries.
“We want people to be part of the solution, not fingered as the problem,” Chan said.