A team at Oregon State University has developed a statistical model that aims to predict which non-native species might become invaders – and arm resource managers to prevent their spread.
Led by economist Munisamy Gopinath and funded by Oregon Sea Grant, the project includes two essential elements for identifying invasive species: how they travel to non-native locations, and whether they could survive and thrive in the new environment. The model also calculates the economic impacts involved in managing the invasive species.
The model is a large, but simple equation. Species that invade waterways often “hitchhike” via recreational travel. Information on where, how, and why people travel to water bodies, along with environmental factors such as temperature, precipitation and elevation, are entered into the equation. The result is a “risk of introduction” that allows resource managers and policy makers to identify species that pose a threat of invasion.
“Not all species are invasive,” said Gopinath, a professor in the OSU College of Agricultural Sciences and director of OSU's graduate program in applied economics. Only transplanted species with specific characteristics that match with specific habitats will thrive, cause harm to the environment, economy and human health – and earn the “invasive” moniker.
“They may not sound like a big deal,” Gopinath said, “but all you have to look at is the quagga and zebra mussels’ invasion,” which caused serious ecological and economic damage to the Great Lakes region and recently began turning up in Western states, much to the alarm of resource managers. “Their invasion in the late 1980s was without fanfare. When these mussels quickly colonized, native mussels lost out, and in addition, water infrastructure became contaminated causing billions of dollars in damages.”
With the information the model provides, policy makers and resource managers could focus resources, along with education and outreach, to specific species and locations before invasive species are introduced, or take hold on a system.
“Prevention is better than a cure,” said Gopinath.
Tania Seimens, a Sea Grant aquatic invasive species educator, likens the project to preventative medicine. “Invasive species are like the cancer of aquatic ecosystems,” Seimens said. “You want to screen and study it, and prevent it all together. That's much better than controlling it once it's there.”
Seimens said that once an invasive species takes hold, the act of controlling or removing it can often be even more damaging to the ecosystem. The use of herbicides and other management practices, for example, can have unwanted side effects like polluting water or killing native plants and animals.
Sam Chan, Oregon Sea Grant's invasive species specialist, said the model could be beneficial to resource managers. “If we had had this model in 2009 we could have shown that the city of Olympia, Wash., is a high-risk spot for New Zealand mud snails,” said Chan.
Mud snails have flourished in Olympia’s Capitol Lake and have reached staggering densities despite attempts to reduce their populations. In 2010 the city drained the lake and filled it with saltwater with the hope of removing around 50 percent of the snails. Unfortunately, it didn’t work.
Gopinath said that there have been no reports of New Zealand mud snails in Oregon’s Willamette River – yet. But according to the model, Willamette Valley waters are at risk for introduction.
The mud snail was the test species that helped Gopinath verify his model's accuracy. Using the model, the team created a graph of a hypothetical mud snail invasion in Olympia. According to Chan, the model's predictions and data from the actual invasion matched up with 95 percent accuracy.
Gopinath says that not only could something like an invasive species outbreak harm Oregon's economy, it might irreparably damage ecosystems by killing native and endangered species, and affect aquatic recreation by tying up boat propellers or polluting water.
“If we know these pathways, how they get from one location to another, we can stop them in their tracks,” said Gopinath. “We need to be mindful that some things that thrive in the tropics may not thrive here. So we need to identify the species that will.”