Phytoplankton Has Declined 40 Percent Globally Since 1950’s

Concentrations of phytoplankton in the world’s oceans have decreased 40 percent since the 1950’s, according to a new study. Using nearly a half-million sources of oceanographic data from the last 60 years, researchers at Dalhousie University in Nova Scotia concluded that the decline of the microscopic organisms correlates with an increase in sea surface temperatures, which leads to increased thermal stratification of the oceans. That stratification limits the upwelling of nutrients from colder waters that feed phytoplankton. Since phytoplankton form the foundation of the aquatic food chain — providing the major source of food for zooplankton, which is a critical part of the diet for larger species — scientists say this trend poses a threat to marine ecosystems worlwide. “This is a definite wake-up call that our oceans are becoming increasingly stressed,” said Daniel Boyce, a marine ecologist and lead author of the study, published in the journal Nature.