When the spring of 2022 turned the page into summer, the Black Sea changed from dark to lively. Artists are rich in phytoplankton that can paint water with colors so brightly that it becomes visible from space.

The phytoplankton bloom is shown in this natural-colored image acquired on June 20, 2022. The image combines the data Visible Infrared Imaging Radiometer Suite (VIIRS) is NOAA-20 satellite and VIRS Finnish nuclear power plant the satellite removes the sunshine and seam lines between the satellite orbits.

Turquoise vortices indicate the presence of phytoplankton following the flow of water currents and vortices. One type of phytoplankton commonly found in the Black Sea is coccolophores – microscopic plankton coated with white calcium carbonate. When these reflective plates are in large quantities, they are easily visible from space and make the water look bright, milky blue.

For most of the year, the colorful works of coccolithophores appear in satellite imagery in May and peak in June. Just a month before the VIIRS data were obtained, the Black Sea was more reminiscent of its name. For example, satellite images on May 20, 2022 show only a faint mark of milky blue water hugging the coast, while most of the sea looked dark blue to black.

But the dark Black Sea doesn’t mean it’s phytoplankton-free; on the contrary, latent was probably present. This type of phytoplankton is common in these waters in the spring and can darken the water more than brighten it. Research in the north-east of the sea suggests that seasonal changes – from smaller siliceous species in early spring to coccolophores in late spring and summer – are related to changes in the type and amount of nutrients available.

The sediments increase rapidly in the spring, when the surface waters are rich in nitrogen and phosphorus. In late spring and early summer, when warm temperatures and fewer storms leave seawater more stratified, less nitrogen mixes with surface waters – a state where coccolithophores are known to dominate. Later in the summer, larger species of diatomaceous earth usually occur. These phytoplankton utilize nutrients that may be caused by the occasional mixing that occurs when the wind changes direction and storms pass.

Seasonal variation in phytoplankton dominant species may have a ripple effect on the structure of the Black Sea food web. For example, coccolophores provide feed for species such as Noctiluca scintillans (sparkle of the sea), while the small lizards feed on pelagic fish and the large lurking jellyfish.

NASA Earth Observatory image based on Joshua Stevens’ NASA EOSDIS VIIRS data LANCE, GIBS / Worldviewand Common Polar satellite system (JPSS). The story of Kathryn Hansen.