Warming seas threaten key phytoplankton species that fuels the food web, study finds

SEATTLE (AP) — For decades, scientists believed Prochlorococcus, the smallest and most abundant phytoplankton on Earth, would thrive in a warmer world. But new research suggests the microscopic bacterium, which forms the foundation of the marine food web and helps regulate the planet’s climate, will decline sharply as seas heat up.

sea surface temperatures are already trending above average and are projected to regularly surpass 86 degrees Fahrenheit (30 Celsius) over that same period.

“These are keystone species — very important ones,” said François Ribalet, a research associate professor at the University of Washington’s School of Oceanography and the study’s lead author. “And when a keystone species decreases in abundance, it always has consequences on ecology and biodiversity. The fo