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Roman Stocker

The sleek orange chairs and elegantly curved desktop in Roman Stocker's office bespeak an eye for detail. That attention to smaller elements is at the heart of Stocker's research with marine microorganisms. The assistant professor in MIT's Department of Civil and Environmental Engineering was recently awarded MIT Sea Grant's Doherty Professorship to further his research into these tiny organisms, which are at the base of the oceans' food web and essential to the oceans' healthy functioning.

"We're interested in how swimming microorganisms actively respond to their environment," says Stocker, "as that strongly influences how nutrients are recycled in the ocean, and ultimately made available to other organisms."

To study fluid mechanics at very small scales, Stocker uses custom-tailored microchannel devices. Tiny channels, with typical sizes of hundreds of microns, are sandwiched between a polymer on the top and a glass microscope slide fused to the bottom. Syringes and pumps generate flows of varying speeds in the channels, allowing the researcher to create nutrient and flow scenarios mimicking those in the ocean.

"My work in microfluidics gives the biologists the ability to look at microorganisms in their environment in a manner that's impossible in the ocean, where the organisms are too small and the conditions too changeable," explains Stocker. In his Doherty-funded research, he will look at whether bacteria can find patches of high nutrient concentrations and get to them before they dissipate by diffusion or flow. If the bacteria reach the patch, they can gobble up nutrients such as carbon and nitrogen- elements initially thought to be lost from the food web. But "if bacteria can rapidly find and consume nutrients, they will be recycling them and ultimately they will be returned to the food web. These processes can totally change our estimate of the carbon cycle in the ocean," explains the researcher.

Stocker, who is gearing up for the field portion of his work, expects this research to help explain how marine microbes find food, avoid predation, and survive in a turbulent and heterogeneous world. That information may aid in fisheries and aquaculture endeavors, as well as in water quality monitoring, and our understanding of how the oceans figure in climate change.

- Andrea Cohen, MIT Sea Grant; and Debbie Levey, MIT Dept. of Civil and Environmental Engineering