Miguel Goni loves a good winter storm.
The same rains that flood Oregon rivers and close schools and businesses signal the beginning of field research on Alsea Bay.
“When it’s raining cats and dogs, that’s when we go out on the bay,” says Oregon State University professor Miguel Goni.
His team braves the pouring rain in a small research boat with little shield from wind, rain or waves in the small estuary in Waldport, Oregon. The data they collect there will help them better understand how floods impact sediment distribution in the bay and ocean.
“These floods can be very destructive in some ways, but they also transport nutrients that can benefit the ecosystem,” Goni says.
The project began in 2011 with funding from the National Science Foundation. The team’s work was made possible with assistance and cooperation from Maggie Revers, Port Manager at the Port of Alesa and Oregon Marine Construction. Goni and associate professor Jim Lerczak began a collaboration to determine when and how much sediment is transported, what it contains and how it impacts ocean organisms.
“Part of the interesting thing about our research in watersheds is there are a lot of people working on ocean research, and lots on land research, but this interface between them is underwhelmed,” Lerczak says.
When winter floods raise river levels, small landslides and the erosion of land result in more sediment being carried toward the ocean. But how much of that sediment will make it to the ocean is a question determined in the bay, an estuary environment where river water and currents meet salt water and ocean tides.
“In estuaries, the flow can go both ways,” Goni says. “ They’re very complicated places because currents reverse with the tides and can move materials up or down the estuary.”
The sediment that is transported from land systems into rivers and eventually oceans contains important nutrients that are necessary to ocean life. But it’s a delicate balance between land and water — while too little nutrient content will leave organisms without enough to survive, too much can be worse, leading to the depletion of oxygen in the water.
Goni says that while researchers know factors like changing water levels impact nutrient distribution, no one has yet determined exactly how those forces interact, or how they might impact marine environments in the long term.
“When it comes to the underpinning knowledge, the fundamental way these systems work, we have some ideas but we don’t have a lot of observations,” Goni says. “In order to understand the role the river plays to the ocean, you have to sample the estuary when the systems are really active, during these floods.”
According to Goni, flooding may be essential during winter when little upwelling, a process that brings nutrients from deeper water toward the surface, takes place.
“When you think about the ocean, out here most of the nutrients come from upwelling, but in winter a lot of the deep water doesn’t communicate with the surface,” he says. “Some of us think these floods that pulse in nutrients from land actually help productivity in the winter time when there are very little nutrients here.”
Gathering data about sediment content and movement is a multilayered process. A surface float anchored in the bay throughout the season measures sediment concentration, salinity and current there, while tripods placed at the mouth of the estuary record the same information from the river’s side. These ongoing measurements are important, Goni says, because the content of the bay can change rapidly.
“In a normal day you’ll have fresh water in the morning and then six hours later you might have intermediary salt water,” Goni says. “In the summer you’ll have nutrients from the ocean like a normal estuary, and in the winter it’s like a muddy river. The estuary itself is very complex but it’s also complex with time because it changes.”
In addition to the static devices, the researchers collect data on the bay in a small boat during flood events. Goni works with undergraduate and graduate students as well as faculty research assistants to perform transects of the bay, in which they progress along a fixed path for 30 minutes, measuring sediment concentration, salinity and current.
At different points in the bay, the team takes samples of the water, many of which will be separated and analyzed for nutrient content in Goni’s lab by undergraduates Lauren Smith and Jackie
Smith began working with Goni in 2011 when she was studying microbiology to gain experience working in a lab. Though she later decided to study accounting, she says she’s continued to work with Goni in the lab and in the field because of the skills she’s learning — and because she enjoys it.
“It’s definitely helpful, because multitasking, processing data and communications are necessary in accounting too,” she says. “Even as a non-science major, this is the most interesting job I’ve had.”
Goni says once lab analysis, observations and data collected over multiple flood seasons are combined, the knowledge gained in this study could be applied to land use policy to better manage the amount of sediment entering the river and, eventually, the ocean. He is planning more field research and hoping for an active flood season this winter.
“The overarching idea we’d like to understand is how these estuaries act during winter floods and what it does to the marine environment,” Goni says. “Land use can control how rivers operate, because the materials they carry have an impact on how the marine system operates.”