Water chemistry may slow mussel spread

PORTLAND, Ore. — In the wake of exotic mussels discovered west of the Rocky Mountains, researchers have found that some waters might be safer from infestation than others. It depends on the chemistry of the water.

Using water-sampling data from 3,000 river sites nationwide, scientists from Oregon State University concluded that the presence of zebra mussels correlated strongly with relatively high calcium carbonate in the water. That's good news for the Willamette and lower Columbia River, as well as other fisheries where levels of that compound are low, they said.

"That's something of a relief," researcher Thorn Whittier said. "But one doesn't want to be too blasé about the issue."

The scientists hope that their study will help to prioritize limited resources in the ongoing battle against aquatic nuisance species.

"Natural resource agencies don't have infinite money, so you have to pick and choose where you're going to try to do enforcement work or where is a good place to put a bunch of boat-washing stations," Whittier said.

Others warn that the discovery is too preliminary.

"I still think we're a ways off from saying, 'We're safe.' I view this as good news for the lower Columbia, but we still want to collect other information to back this up," said Stephen Phillips of the Pacific States Marine Fisheries Commission in Portland.

Calcium carbonate leaches into water from limestone formed beneath ancient sea beds. By contrast, volcanic basalt, which characterizes rivers in the Cascade Mountains, is low in calcium.

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