In polar food webs, microbes capture energy from the sun and become nutrients for all the animals above them in the food chain. But unlike larger creatures like polar bears and whales, microbes have short lifespans, sometimes as brief as a few days, making them much more responsive to what’s happening in their environments. In the past six years, Fong has measured oxygen concentrations in microbial communities found in sea ice at both poles to assess what biologists call abundance, which is a measure of the nutrient availability in an environment. Her research could provide a window into the types of species that are able to flourish and those that may flounder.