Scientists and resource managers are working to stem the flow of nutrients into the Black Sea and restore water quality, which can suffer due to an overabundance of phytoplankton.
This natural-color image captured by the moderate resolution imaging spectroradiometer (MODIS) on NASA’s Terra satellite shows the eastern half of the Black Sea onMay 18, 2012. Milky, light blue and turquoise-colored water in the middle of the sea is likely rich with blooming phytoplankton that trace the flow of water currents.
Closer to the coast, the colors include more brown and green, perhaps a brew of sediment and organic matter washing out from rivers and streams, though it may also be a sign of phytoplankton. Puffs of spring clouds linger over parts of the coastline. Enriched by nutrients carried in by the Danube, Dnieper, Dniester, Don and other rivers, the waters of the Black Sea are fertile territory for phytoplankton growth.
The bounty is a mixed blessing. Phytoplankton are the “primary producers” of the seas and oceans. These plant-like, microscopic algae, bacteria and protists use chlorophyll to make their own food from sunlight and dissolved nutrients. But extreme and persistent blooms can suck most of the oxygen out of the water—a process known as eutrophication—and suffocate other marine life. Predominance by certain phytoplankton species can also crowd out others that give the sea its diversity of plant and fish life.