Monitoring Marine Life–In Close to Real-Time–with eDNA Sensors

An optical sensor smaller than a postage stamp could help coastal communities monitor some of the world’s largest marine protected areas.

On a warm day this spring, an airplane carrying Stanford experimental physicist Halleh Balch touched down on the island nation of Palau in the Western Pacific as a brewing typhoon piled dark clouds on the horizon. In her luggage, Balch had packed a thumbnail-sized sensor that had been months in the making in California to detect fragments of DNA recently shed into the ocean by passing marine life.

Other technologies have enabled scientists for years to detect species in a habitat based on sloughed scales, tissues, and other genetic material known as environmental DNA, or eDNA. But few have been able to deliver that information in close to real time, especially in a marine environment, where scientists and natural resource managers say there’s an urgent need to track the array of marine life facing climate change impacts like coral bleaching, warming seas, and fish migrations.