Coccolithophores in the Bering Sea

The Bering Strait—the stretch of water between Siberia and Alaska—features some of the world's most productive ocean waters. This Sea-viewing Wide Field-of-view Sensor (SeaWiFS) image shows phytoplankton covering vast stretches of water. Phytoplankoton are microscopic plants that form the base of the marine food chain.

The green water on the left features a high concentration of phytoplankton. On the right, off the west coast of Alaska, a bloom of a specific type of phytoplankton, coccolithophores, appears bright blue-green. Coccolithophores have white calcium-rich shells that reflect sunlight and brighten the water. The coccolithophore shells—coccoliths—have persisted in the Bering Sea since 1997, but appear to be fading.