Falling oxygen levels are putting ocean ecosystems on life support
Jessica Camille Aguirre writes: People who make their living catching fish on the open ocean first noticed the strange phenomenon a few decades ago. It occurred in the shadow zones, the spots between the great ocean currents where sea water doesn’t circulate, off the coasts of Peru, West Africa, and California. The fisher people shared the knowledge among them like a common secret, a bounty that had an even stranger explanation: Sometimes, when the conditions were right, fish would swim…