“Rivers and lakes are globally affected by the loss or addition of fish species. This is particularly true for the Missouri River, which has both endangered native fish species and at least 30 introduced fish species,” Wesner said. “This work will help us to predict the consequences of those changes for other fishes and other parts of the broader ecosystem.”

The project includes a study of insects, fish and their diets in the Missouri National Recreational River. It will also include experiments at USD’s experimental aquatic research site (ExARS), which contains 24 outdoor artificial streams in which students can observe and study ecological interactions in freshwater ecosystems.

The project is supported through NSF’s Early Concept Grants for Exploratory Research program, which funds research that is considered high-risk and high-payoff. In this case, the payoff is a key test of ecological theory that challenges how freshwater ecosystems are typically studied and managed.

“Traditionally, we’ve assumed that water and land function as separate ecosystems,” said Wesner. “But we now know that birds, spiders, mammals and bats are affected by changes in river ecosystems, like invasion or extinction of fishes.”

However, predicting how a particular invasion or extinction will impact other organisms in water or land is difficult, because rivers are incredibly complex.

“One way of reducing that complexity is to think of each species in the ecosystem as ‘who-eats-whom,’” said Wesner.

The network that results from this is called a food web. But nearly all studies of food webs ignore the fact that organisms change what they eat, and who eats them, as they grow. In addition, organisms change where and how they live during their life. Wesner says that incorporating this information may improve scientists’ ability to predict the consequence of species loss or addition in ways that traditional approaches cannot.

In addition to providing opportunities for USD students to learn about freshwater ecology, the project will also help local children and their parents learn about the diversity of life in rivers.

“The artificial streams at ExARS are perfect for observing freshwater diversity in a safe environment,” said Wesner. “Juvenile dragonflies look like space aliens, and fish are always fascinating to watch.”

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