NASA has put an end to the confusion over the mysterious hues of the Bosporus, which have changed from dark blue to a bright turquoise color in recent days.

The turquoise color stretches along the Bosporus to a large portion of the western Black Sea, which puzzled residents and raised questions about pollution.

NASA explained that the color was caused by phytoplankton, single-celled microscopic organisms that make food from sunlight and nutrients in the water. The flow of the Danube and Dnieper Rivers into the Black Sea provides nutrients for the tiny creatures.

The Aqua satellite's Moderate Resolution Imaging Spectroradiometer (MODIS) captured its first images of the phytoplankton boom in the Black Sea on May 29.

Fishermen have predicted a rise in anchovy yields this year due to the plankton, which provide food for fish and shellfish. However, when in large groups, phytoplankton can suck oxygen from the water and damage other marine life.

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