Marine food chain’s lowest link declining

LOS ANGELES – The world’s phytoplankton appears to have been disappearing at a rate of about 1 percent a year for the past century, researchers announced Wednesday, a disturbing long-term trend for the microscopic algae that form the basis of the marine food chain and produce much of the world’s oxygen.

In reporting their findings in the journal Nature, the Canadian team said that since 1950 phytoplankton biomass has shrunk by about 40 percent. “A global decline of this magnitude? It’s quite shocking,” said Dalhousie University marine scientist Daniel Boyce, lead author on the study.

The new study combines historical records of ocean clarity with modern satellite data, the latter of which has only been available since the 1970s. Together, the modern and historical information provide an accurate long-term view of the state of phytoplankton.

The historical data was based on measurements of ocean clarity which involved lowering what looked like a white dinner plate into the ocean until observers lost sight of it. Water murkiness increases or decreases depending on the amount of phytoplankton or, more specifically, the plant’s green chlorophyll.

Thus, the scientists were able to convert historical data into specific measures of phytoplankton population, using it with the modern information to create a timeline of the algae over the past century.