Keep the Mussels Out

Authored by: Amy Schneider, Danielle Goodrich, Sam Chan, Tania Siemens, Jennifer Lam

At a check station along the Oregon border, Oregon Department of Fish and Wildlife (ODFW) technicians intently watched a bucket full of water. It wasn’t the water they were interested in, but rather the creatures found clinging to a boat, that removed and placed inside a bucket of water to watch them open their shells, proving they were alive. They were invasive zebra mussels, and they weren’t supposed to be there.

They had hitched a ride on a boat from Lake Erie, and although the boaters had stopped at a check station in Wyoming where their boat was pressure washed and cleansed of mussels, the technicians there had missed a spot. A week had passed since the boat left Lake Erie, but the eight zebra mussels that remained were still alive when they reached the Oregon border. Because of the check station, the mussels did not make it into the state, and they are currently an invasive species that hasn’t established in Oregon and the Pacific Northwest… yet.

Zebra Quagga Mussels

Figure 1. Zebra and quagga mussels are the only freshwater mussels in North America that can attach to objects using byssal threads, the adult. The most notable different between the two species is that the zebra mussel has a distinct flat edge, while the quagga mussel doesn’t. (Amy Benson, U.S. Geolocial Survey)

Quagga and zebra mussels are freshwater mollusks that were first unintentionally introduced to the Great Lakes  in the United States from the Caspian Sea (right next door to Sochi, Russia, the host of the 2014 Winter Olympics) in the early 1990s through the ballast water of ships from Europe. Such an invasion would not had been possible in the Great Lakes from ocean- going ships  had it not been for a series of canals and locks constructed in the late 1800’s that allowed access to the Atlantic ocean. Most notably, they have invaded the Great Lakes and Lake Mead in Nevada, causing a whole host of problems, from over-filtering the water to clogging up drainage pipes with their prolific growth.

Figure 2. Viewers can appreciate the rapid rate at which these mussels invaded, seen on a time lapse map of zebra and quagga mussel confirmed sightings created by the U.S. Geological Survey.   Since their introduction to the Great Lakes, zebra and quagga mussels have spread across the United States. Note that the Pacific Northwest states are the only region in the USA that are still free of mussels. Keep in mind while watching, that the dots represent sightings of either mussel and do not necessarily represent their current established range. (US Geological Survey)

Teachers helping to prevent the mussel invasion

Teachers are doing their part to prevent the spread of these damaging mussels to Oregon, Washington and California by educating students about these highly invasive species. A classroom lesson plan is available for students to learn about the impacts of the mussels and specifically about the drying time required to prevent their spread. Through the activity, students will discover that the amount of time that a boat must dry before entering a new waterway varies based on climate. Through the WISE Mussel Quarantine Model teacher lesson plan, students will get a chance to learn about the harmful impacts of the zebra and quagga mussels and ways to prevent their spread to new regions, including the Pacific Northwest. The activity utilizes the 100th Meridian Initiative Drying Time Estimator for Zebra/Quagga Mussel Contaminated Boats to display the drastic differences that precipitation, humidity and temperature have on the desiccation or drying time required to prevent the spread to a new waterway. Students can gain familiarity with the biological tolerance of these invasive species, climate science and math to make predictions on how long it takes to desiccate these invasive mussels through the use of simple and intuitive models.  These models can help students see math and science as tools they can use to help them.


sample model

Figure 3. Models can initially seem daunting, but this figure demonstrates that virtually all models operate on the same principle. With a certain input (in the case of the mussel model above, that would be location and date) and pre-existing data (predicted climate conditions for each location and date), a certain prediction will be given (drying time to desiccate mussels). (Danielle Goodrich)

Zebra Quagga Mussels Characteristics

The goal in Oregon is to keep the invaders out, and five check stations along the Oregon border are helping to make that happen. According to Rick Boatner, Invasive Species Coordinator for ODFW, the check stations caught and decontaminated 18 invasive species-ridden cases over the past year. A recent Salem News article, Paddlers -Remember to Carry Your Aquatic Invasive Species Prevention Permit, reiterates that all manually powered boats 10 feet or longer are required to purchase and carry a permit as well as stop for an AIS inspection when trailering a boat or paddle craft past an open station. Boatner explains that “the program is designed to educate boaters about the threat of aquatic invasive species and what boaters can do to prevent the spread of aquatic invasive species that are already in Oregon, like the New Zealand mud snail”. Access the 2013 Program Report to learn more about Oregon’s Aquatic Invasive Species Prevention Program. Just this last week a truck and trailer had bypassed the Ontario, OR check station and were stopped by a Malheur County Sheriff. Inspections found that the boat was carrying a large number of juvenile quagga mussels on the hull and outboard motor from Texas. ODFW boat inspectors decontaminated the pontoon boat carrying invasive quagga mussels and protected Oregon waters from this threat.



Figure 4. There are a variety of potential pathways for invasive species that are associated with human activities. Adapted from Invasive Species Pathways Team Final Report (USDA, 2003)

Boatner says that if a quagga or zebra mussel invasion were to happen, it would be costly to the state of Oregon. “Currently, there’s not a good method for eradicating a mussel invasion,” he confesses. Once they’re here, they’re typically here to stay, and it’s not always cheap to deal with them. According to ODFW, the power industry in the Great Lakes area has cost an estimated $3.1 billion over a six year span.

Prevention is the best way to keep quagga and zebra mussels from harming Oregon’s watersheds, and the recent addition of check stations to Oregon’s borders has played a part in screening out infested watercraft. As always, it’s important for boaters to clean, drain and dry their watercraft before moving it from one body of water to another. Under the right conditions, quagga and zebra mussels can live up to 22 days out of the water depending on the local temperature and precipitation, so never underestimate the resilience of an invasive species.

dont move a mussel2

Figure 5. Rick Boatner stands next to an educational invasive mussel sign on a trailer at a boat inspection station in Arizona. (Oregon Sea Grant Invasive Mussels in the West)



Learning about Invasive Species Impacts and Their Adaptability

The invasion of zebra and quagga mussels has a large impact on the local ecology, infrastructure, and waterways. Therefore, removal to prevent spread is a common necessity in invaded waters. Lake Piru has been found to be the first host of quagga and zebra mussels in Southern California that doesn’t receive water from the Colorado River. This leads to conclusions that the mussels were spread through other means, possibly hitchhiking on the boats or equipment of recreational boaters. On March 28, 2014, divers set out in Lake Piru to scrape mature quagga mussels off of underwater surfaces and were surprised to find an abundance of tiny mussels, indicating a recent spawn occurred sooner than expected. In response to this, there are plans to add predatory fish and tarps to the infested zone in order to aid in control efforts. Scientists, like Dr. Carrie Culver at California Sea Grant stress the importance of monitoring and understanding the environmental parameters of areas, such as Lake Piru, which are vulnerable to the spread of invasive species. Read the article Invasive mussels spawned sooner than expected, divers find for the full story.

MarinaLakePiruJan2014 659 Small

Figure 6. Recreational activities in Lake Piru make it especially important to monitor invasive species and environmental parameters that allow for their spread (Dr. Carrie Culver, California Sea Grant)

Models like the 100th Meridian Initiative WISE Mussel Quarantine Model lesson plan are great representatives of predicted outcomes based upon what we currently know. Yet, the wonderful and daunting fact about science and nature is that we don’t know everything and this especially applies to the environmental tolerances or limitations of invasive species which are continually being defied. One of the reasons that zebra and quagga mussels are successful invaders because they are able to withstand conditions that we didn’t think possible, for example they went undetected in Lake Mead for some time because scientists didn’t search deep enough for them.  That is why it is important to educate boaters and paddlers to clean, drain, and dry their water crafts and to always keep an eye out for the mussels and other invasive species in all sorts of habitats.


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