Early Detection Monitoring May Not Be Sufficient for Invasive Mussels in the Columbia River Basin

Science Center Objects

The ecological and economic costs of an invasive quagga or zebra mussel infestation in the Pacific Northwest of the U.S. would be significant. The development of invasive mussel monitoring programs in the Pacific Northwest provides a unique opportunity to evaluate a regional invasive species detection effort early in its development. Although efforts are underway to monitor for the presence of invasive mussels, assessments of whether these efforts provide for early detection are lacking. A recent article in Environmental Monitoring and Assessment, scientists from USGS and Washington State University find that while detection efforts have increased dramatically over the past few years the existing programs may not be sufficient to detect these invasive mussels early enough to prevent them from being spread to other areas. USGS and Washington State University are working together with, private, state (Idaho, Montana, Oregon, and Washington), tribal entities conducting early detection monitoring for quagga and zebra mussels to provide regional context and evaluate the development of early detection monitoring programs.

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Map of study area

Map of the study area that includes the states of Idaho, Montana, Oregon, and Washington. The Columbia and Snake rivers are the two largest rivers in the Columbia River Basin which is shown as a shaded area on the map. (Credit: Tim Counihan, USGS. (Public domain.)

Zebra mussels, brought to the U.S. from Europe in ship’s ballast water, were first discovered in the Great Lakes in the mid-80’s. Since then, these invasive mussels have caused extensive damage to ecosystems and in-water infrastructure. Millions of dollars have been spent to eradicate these mussels, as well as to control and limit their spread to other bodies of water. The Columbia River Basin now stands as one of the few areas in the U.S. not invaded by these small and highly prolific mollusks. Recent discovery of invasive mussels in Montana has people across the Northwest States wondering how close these invaders are to making their way into Columbia River Basin waters.

In a recent article in Environmental Monitoring and Assessment, scientists from USGS and Washington State University found that current efforts to detect invasive mussels in the Columbia and Snake Rivers may not be sufficient, which could allow mussels to establish and spread. The study was conducted in cooperation with private, state, and tribal entities, to assess early detection monitoring for quagga and zebra mussels and provide a regional context for the development of early detection monitoring programs. The report found that the effort to monitor for invasive mussels increased substantially from 2012 to 2014, that efforts were distributed across risk categories ranging from very low to high, and that substantial gaps in our knowledge of both introduction and establishment risk exist. The estimated volume of filtered water required to fully census planktonic taxa or to provide probability detection of rare taxa was high for the four reservoirs examined. Scientists conclude that the current level of effort expended does not provide for high-probability detection of larval mussels when they are rare in these reservoirs. Without early detection and subsequent mitigation, these mussels are likely to spread throughout the region and negatively impact both the economy and ecology.

“Recent studies suggest that the ecological and economic costs of an invasive mussel infestation in the Pacific Northwest would be significant,” said Steve Bollens of Washington State University. “The invasive species are known to multiply rapidly and damage beaches, clog boat motors, irrigation systems and dams, harm fish and wildlife and foul in-water infrastructure. Early detection of invasive quagga and zebra mussels will be important for quick response efforts.” The study suggests several ways to improve monitoring including a re-evaluation of the actual geographical effort and increasing monitoring locations and employing a combination of existing and new emerging techniques. The study also calls out the need for better assessments of both risk of introduction and risk of establishment that would help direct monitoring to areas that are at highest risk of invasion.

“This study suggests ways that ongoing monitoring efforts can be improved to help control the spread of these invasive species,” said Tim Counihan of the U.S. Geological Survey Western Fisheries Research Center.


Table - Agencies conducting mussel monitoring

Agencies conducting monitoring for the presence of larval dreissenid mussels that participated in the survey and the state(s) they monitored. Credit: Tim Counihan, USGS. (Public domain.)