University of California, Irvine scientists have created a new high-resolution map that shows where photosynthetic organisms thrive or are forced to adapt to limited resources. Led by Adam Martiny, professor of Earth system science and ecology & evolutionary biology, the study utilized the information embedded in ocean microbes, particularly phytoplankton, to act as a biosensor of ocean health.

Phytoplankton activity is tightly regulated by nutrient supply, and changes in the availability of nutrients may lead to alterations in the microbe genome that can be measured. Because phytoplankton have rapid life cycles, researchers can track changes in their genomes that may serve as an early warning system for oceanic environmental change.

“Nitrogen, phosphorus and iron limitation in many surface ocean regions is nearly impossible to detect through chemical analysis of water samples; the quantities of these elements are just too low,” said lead author Lucas Ustick, a UCI graduate student in ecology & evolutionary biology. “But quantifying shifts in Prochlorococcus genes involved in the uptake of major nutrients, and combinations thereof, provides a strong indicator of the geography of nutrient stress.”

The research team also included Alyse Larkin, postdoctoral scholar in Earth system science; Melissa Brock, graduate student in ecology & evolutionary biology; Keith Moore, professor of Earth system science; Nathan Garcia, project scientist in Earth system science; Catherine Garcia, a graduated Ph.D. student from Earth system science; Jenna Lee, a graduated UCI undergraduate student and Nicola Wiseman, graduate student in Earth system science.

The study was published in Science.