Undergraduate student studies the effect of pollution on watershed microbes

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Sofia Suesue filters water in the lab. (Photo credit: S Suesue)

Before joining the University of Hawaii at the Mānoa School of Ocean and Earth Science and Technology (SOEST), Sofia Suesue was pursuing an associate’s degree in natural science at Windward Community College and enrolled in a summer oceanography course at uh Manoa, Mauka from Halau Ola Honua to Makaiwhich focused on the management of watersheds on Oʻahu.

“Through the Mauka to Makai course, I became more interested in studying oceanography and found pursuing a career in research to be a more possible aspiration than I originally thought,” Suesue said. . “Also, with my experience in the course, I thought I could use what I learned [in GES] to one day help solve some of the environmental problems of our coastal areas.

woman fetching water
Sofia Suesue collects water from a channeled stream. (Photo credit: S Suesue)

Raised on the windward side of Oʻahu, environmental science had always intrigued Suesue. Michael Guidry, Summer School Coordinator and Director of Global Environmental Science (EMS) program, encouraged her to transfer to SOEST after graduating from Windward CC.

Caffeine, herbicide, antibiotic pollution of watershed microbes

After joining the EMS As part of her bachelor’s degree program in the Department of Oceanography, she focused her thesis research on the potential impacts of pollutants, including caffeine, the herbicide glyphosate, and the broad-spectrum antibiotic sulfamethoxazole used to treat infections, on microbial communities in river and coastal environments.

Suesue surveyed the Kahaluʻu-ʻĀhuimanu stream system on the windward side of Oʻahu to measure how the concentration of the three contaminants has changed from inland to coastal environments. She was guided by (SOEST) sponsors Henrietta Dulaiprofessor of earth sciences, and Craig Nelsonassociate researcher at the Department of Oceanography and Hawaii Subsidy from the sea.

His findings suggest that caffeine concentration degrades from the inland part of the watercourse towards the shoreline and may impact microbial metabolism. His research also showed that glyphosate and sulfamethoxazole were stable in marine and freshwater systems with higher concentrations in coastal sections of the waterway, suggesting that they can be delivered to coastal areas. where they can persist.

Sofia Suesue

“The observation of potential attenuation of pollutants by microbes only in the unchannelized inland parts of the river system suggests that inputs from all other areas may be more likely to be exported to coastal waters, which could lead to an increase in environmental and public health issues related to the presence of pollutants,” Suesue said.

Testing the response of microbes to contaminants

After this survey, researchers selected four sites across the stream system and two within Kāneʻohe Bay. They conducted a laboratory experiment in which they added contaminants to water samples taken from these areas and observed changes in contaminant concentration and microbial density over the course of two weeks.

“If we observe a decrease in contaminant concentration and a significantly higher cell density, this may suggest that a contaminant was being used as an energy source for the microbes,” Suesue said. “This is what we observed in the samples to which we added caffeine. It appears that this may impact microbial metabolism in this system.

The team was struck by the persistence of the three compounds in marine ecosystems, noting that “these experiments add to growing concern about the long-term persistence of chemicals associated with human pollution sources.”

For more information, see SOESTthe website of.

–By Marcie Grabowski

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