Oil spill scenario

May graduate Anna Hilger’s master’s thesis work focused on how microbes would react under the stress of an oil spill in the La Crosse River Marsh.

May graduate Anna Hilger’s master’s thesis work focused on how microbes would react under the stress of an oil spill in the La Crosse River Marsh.

Study shows La Crosse River Marsh would have a different microbe community under oil spill stress

Over the past year, Anna Hilger was researching an important question related to UW-La Crosse’s neighbor — La Crosse River Marsh.

The microbiology graduate student wondered if a train derailed and spilled crude oil into the city’s marsh, what would happen to the community of microbes living there. Although nearly invisible to the human eye, microbes are drivers of important reactions in the environment — from oxygen production to decomposition. Needless to say, their decline or demise in an ecosystem could be a huge burden on the cycle of life.

Hilger, who graduated in May and recently wrapped up her master’s thesis work, now has an answer to her question. But, as science goes, it is an answer that begs more questions.

Hilger found that makeup of the community of microbes in an oil-polluted marsh changed. She and faculty mentor, UWL Associate Professor Bonnie Bratina, created an artificial oil spill scenario by mixing marsh water and sediment with crude oil in a container. After testing samples from the artificial marsh in her lab, she found a specific kind of microbe with the ability to chew up crude oil was thriving.

It’s not news that bacteria and other microbes can consume oil. Oil degrading microbes have long been a remedy for cleaning oil spills. But their natural rise in a contaminated marsh begs the question of what their abundance might mean for other important marsh microbes not as keen on consuming oil. Hilger’s research did not delve into the question of whether this new community makeup was good or bad for the marsh ecosystem, but she is hopeful a future graduate student can tackle those questions.

She found the impact of increasing oil degrading microbes was felt most heavily in the water and not the sediment, as the oil tended to stay at the top of the water. That may change with a heavier grade of oil, she added.

Hilger, originally from Bloomer, Wisconsin, is grateful for the opportunity to conduct research in college.

“It helped me figure out what I truly am passionate about and what I’m willing to put in the long hours to achieve,” she says. “It was hard work, but I know it is worth it because it is something I really do care about.

Hilger’s research was funded by a UWL Research, Service, and Educational Leadership (RSEL) grant, as well as funding from the Microbiology Department and the UWL River Studies Center.