Large, persistent phytoplankton bloom in the Bering Sea in 2014


Beginning in July 2014, satellite images of the eastern Bering Sea shelf began to show patches of milky, aquamarine water. The unusual water color, caused by a bloom of coccolithophores, continued into the fall. Coccolithophores are phytoplankton, single-celled marine plants that live in large numbers throughout the upper layers of the ocean. Unlike any other plant in the ocean, coccolithophores surround themselves with microscopic scales made of calcite. These scales, known as coccoliths, are shaped like hubcaps. When coccolithophores bloom, the calcium-rich coccoliths turn the normally dark water a bright, milky aquamarine, making coccolithophore blooms easy to spot in satellite imagery. In 2014, the Bering Sea experienced unusually warm conditions that were accompanied by a large coccolithophore bloom. Fortunately, a research cruise from NOAA's EcoFOCI Program was in the right place at the right time. A satellite image from September 26 shows the aquamarine bloom. The white circles on the image indicate sampling stations occupied by NOAA's research vessel Oscar Dyson.

The cruise measured temperature, salinity, and nutrient content of the water. In addition, nets were used to collect small floating animals called zooplankton. Bird and mammal observers were also on board. Before 1997, coccolithophore blooms in the Bering Sea were rare. A large bloom occurred in 1997 and for several years thereafter. During the 1997 bloom, the bloom was associated with a die-off of Shearwaters, a seabird commonly seen in these waters. It was thought that the bloom may have made it difficult for the Shearwaters to see their zoolankton prey from the air. During the 2014 cruise, many dead birds were also observed (mostly Murres this time). This die-off may also be associated with the coccolithophore bloom. The data collected by the EcoFOCI cruise will allow scientists to examine the causes and consequences of the coccolithophore bloom..