Brianna Guijosa is an undergraduate who has spent the last two summers at RMBL studying how decomposition adds nutrients to the soil. The decomposing subjects are mice, and the creatures converting them to soil nutrients are carrion beetles and flies.

While a student at East Los Angeles College, Brianna got a scholarship from the National Science Foundation program Research Experiences for Undergraduates (REU) to create her own research project at RMBL.

The serendipitous way that Brianna landed on mice and carrion beetles as subjects is amusing to her. She was reading a newspaper tacked onto one of RMBL’s outhouses, and a story caught her eye. It seems that human waste left by hikers and campers in the outdoors has become a real issue because it takes so long to decompose. A project focused on recycling sounded appealing. Working with human feces? Not so much.

That’s when she seized on the idea of studying how the decomposition of small mammals helps fortify the soil, and she enlisted insects that make a living recycling dead things.

Mentored by Dr. Rosemary Smith, Brianna set up an experiment to study the impact of carrion beetles on soil nutrition. Using dead mice as the food source, she set the beetles and other insects to work breaking down the carcasses. Then to measure the soil quality, she planted oats in the enriched soil, harvested them after about two weeks, and measured the root weight fraction, which is the comparison between the weight of the root and the plant.

Roots that have to work harder to find nutrients are larger and heavier, whereas roots that find plenty of nutrients are lighter and smaller. In other words, more nutrients equal lighter roots; sparce nutrients mean heavier ones.

Among the treatments Brianna tried was piercing a mouse carcass to release nutrient-rich body fluids into the soil, simulating what would occur with a body ravaged by beetles. Out of all the soil treatments, Brianna found that the soil affected by the black carrion beetles and flies was the most nutritious.

Brianna herself caught the science bug at a young age. Growing up in Elk Grove, California, near Sacramento, she had easy access to wetlands, wildlife preserves, riparian habitats, mountains, and other natural wonders. Her affection for wildlife stayed with her when the family moved to Los Angeles.

At East Los Angeles College, a stroke of luck put her in a biology class taught by Dr. Jimmy Lee, who has served as RMBL’s undergraduate education program coordinator for many years. Dr. Lee has inspired many students to take advantage of the REU program and earn a spot at RMBL conducting authentic scientific research. In the fall, Brianna will continue her pursuit of science at Cal Poly Humboldt in Arcata, CA.

Brianna’s singular project was a source of pride. “It was cool that I was the only person doing a project like this at RMBL,” she said. At the same time, she was grateful to be welcomed into this supportive environment. Without the help of Dr. Smith, she said that she couldn’t have done the project. Staff members from administration to maintenance were helpful, too. Thanks to the REU grant and RMBL hospitality, she felt fortunate that even as a community college student, she was included in the science community.

She could interact equally with people from similar backgrounds and those from ivy league schools. As far as the scientists, she said “It was awfully nice to have access to all the wisdom.”

Beyond its scientific impact, RMBL teaches students that mixing with people from different backgrounds can introduce you to new outlooks, not only on science but also on life. After all, as humans we are in one sense all the same, but in another sense completely different, each of us molded by our unique circumstances.

And luckily, it’s the differences that yield discoveries.


Brianna Guijosa is a recipient of the NSF Research Experiences for Undergraduates scholarship and a student entering California State Polytechnic University, Humboldt. She plans to earn her Bachelor of Science degree in Biology with a Wildlife, Wildlife Ecology, Conservation, and Management concentration, and she hopes to eventually work for the National Park Service. She lives in Los Angeles with her family.