Exploring the Hidden World: Benthic Animal Research in Agricultural Channels of Oregon

By Ben Davis


ahiza De Thomas puts on fishing waders and climbs down into the water—an agricultural channel, only a foot deep and a few feet wide—that cuts between a hazelnut orchard and a grass seed field. It may look small, but this channel plays a critical role in crop production and the surrounding ecosystem. For starters, it serves as host and hatching grounds for aquatic insects and macroinvertebrates, which provide a fundamental food source for small animals like fish, birds, and bats.

“Most people don’t realize that dragonflies start their life as larvae on the riverbed, and then emerge from the water to become flying insects,” says De Thomas, wading through the shallow stream. She checks the first of her emergence traps for adult insects that have emerged, and then compares them to her benthic samples.

“These benthic samples are the first stages of life,” she says, holding up a small plastic baggie for inspection in the morning sunlight, revealing a hidden world of tiny organisms usually unseen by human eyes.

Rahiza De Thomas is a master’s student in the Department of Fisheries, Wildlife, and Conservation Sciences. Her research focuses on benthic animals in agricultural channels like this one in Yamhill County.

Benthic refers to the floor or bottom level of any body of water, where a variety of small animals and invertebrates hatch or live. By checking the traps and studying the animals at various stages, from larval to full adult, De Thomas aims to learn more about which types of animals emerge at what time, and how that impacts the populations of other species and connects up the food chain.

This hidden world is fascinating to De Thomas, but not new to her. She began studying benthic animals during her bachelor’s degree program on her home island of Puerto Rico, primarily focusing on rivers and streams. Following the devastation of hurricanes Maria and Irma, a one-two punch that ravaged the island in 2016, De Thomas moved to Texas, where she started taking OSU classes online toward a certificate in Fisheries and Wildlife Sciences. There, her work focused on small ponds and standing bodies of water.

Through her coursework, she soon learned about an opportunity to earn a master’s degree and expand her research to agricultural channels, working on a project led by Professor Guillermo Giannico and Associate Professor Ivan Arismendi in the Department of Fisheries, Wildlife, and Conservation Sciences at OSU.

This work is valuable to both agricultural communities and conservation efforts across the state. Agricultural channels and waterways provide irrigation and drainage systems for farming, and their aquatic life serves as bioindicators of water quality and overall ecosystem health. Studying and monitoring benthic animals can help pinpoint problematic areas and paint a bigger picture of changing conditions.

Beyond De Thomas’ studies, she has found a sense of community at Oregon State. “Being part of the OSU community has helped a lot. I am Latina, and OSU has so many students from other countries like Paraguay, Columbia, and other South American countries. Learning about those other cultures has been amazing.”

After graduating, De Thomas hopes to return home and utilize her education to help conserve the island while also growing its tourism economy. “It’s a small island but there are so many ecosystems there—dry forests, rain forests, mangroves, coral reefs, caverns, lagoons—and I want to take my knowledge home and help preserve all those ecosystems so that visitors can enjoy them and help the economy of Puerto Rico.”

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