NASA satellites have captured a massive blue-green bloom forming along the shallow coastlines of New Jersey, Delaware, Maryland, and Virginia. The phenomenon, first observed in mid-April, has grown into vast swirling patterns visible from space.
The bloom appears as a mix of blue, green, and brown waters, stretching for hundreds of kilometers along the eastern seaboard. NASA explains that the phenomenon is driven by a combination of river outflows, spring storms, and a dense population of microscopic marine organisms known as phytoplankton.
Monitoring such blooms is key to understanding ocean health, as these organisms play a crucial role in oxygen production and serve as a foundational food source for marine ecosystems. Satellite instruments like MODIS on the Aqua satellite and the new PACE mission allow scientists to track these events with unprecedented detail, analyzing ocean color to determine organism types and densities.
How the Bloom Forms and Spreads
The swirling patterns seen from space are influenced by both natural water movement and the biology of the organisms themselves. Kyle Scotese from the International Society for Diatom Research notes that:
“Many types of algae, including cyanobacteria, dinoflagellates and diatoms, can generate massive populations with densities greater than 15,000,000 cells per liter, stretching for hundreds or even thousands of square kilometers in water bodies,” adding that: “these blooms can proliferate and dieback in a matter of days or return seasonally for decades.”
Microscopic view of a diatom chain, a type of phytoplankton commonly found in ocean blooms. Credit: International Society for Diatom Research
River outflows and spring storms also contribute to the phenomenon by stirring sediments and nutrients into shallow waters, providing fertile conditions for these microscopic lifeforms. NASA Earth Observatory reports that these environmental factors combine to produce the ghostly blue-green and brown coloration visible in satellite imagery.
Identifying Organisms From Space
The Plankton, Aerosol, Cloud, Ocean Ecosystem (PACE) satellite has improved the ability to identify bloom composition remotely. By analyzing light wavelengths, researchers can determine which phytoplankton species dominate a bloom. The U.S Space Agency highlights that diatoms typically dominate early spring blooms, though some signs of coccolithophores, which create a chalky turquoise appearance, are also present.
Sunlight interacting with substances in seawater, such as chlorophyll, gives the ocean its color and reveals the patterns. Anna Windle, a research scientist at NASA’s Goddard Space Flight Center, explains that these measurements allow scientists to monitor global phytoplankton distribution and track the ecological role of these organisms with precision.
Swirling phytoplankton colors the Atlantic waters. Credit: NASA
Impact of the Blooms on Marine Ecosystems
Phytoplankton are responsible for producing an estimated 20 to 40 percent of Earth’s oxygen and form the base of the marine food web. The same source adds that coccolithophore-dominated blooms, which appear milky or turquoise, provide additional insight into ocean chemistry due to their calcium carbonate plates called coccoliths.
Coccolithophore (left) and its individual coccoliths (right) under a microscope. Credit: Hiroshima University
While these blooms are natural and usually temporary, their size and composition are closely monitored to assess ocean health and detect potentially toxic events. For now, the eastern U.S. swirl shows no signs of toxicity and as noted by Oscar Schofield, an oceanographer at Rutgers University:
“Unless big river outflows or storms replenish the nutrients, we’ll likely see this bloom start to decline in the coming weeks.”