Bosphorus Strait, which divides Europe and Asia in Turkish city Istanbul, has suddenly undergone a change in color.

While this surprised residents, scientists are quick to attribute it to “plankton explosion” across the Black Sea.

Not A Pollution Spill Or Serious Phenomenon

Spring phytoplankton blooms in the area continued to grow in the early part of June, as captured by the Moderate Resolution Imaging Spectroradiometer (MODIS) on board the Terra satellite of NASA last June 8.

The sudden transformation of the typically blue waters of Bosphorus Strait surprised locals, which posted some images on social media. Some feared of a pollution spill, while others suggested an earthquake rocking the Aegean region last Monday, June 12.

Scientists were quick to downplay the seeming mystery of color change that went with a sharp smell of water.

“This has nothing to do with pollution,” said Hacettepe University professor Ahmet Cemal Saydam in an AFP report, instead pointing to the explosion of phytoplankton Emiliania huxleyi.

In fact, the environmental science expert added, the occurrence was actually good for anchovies, which is a staple food in Istanbul.

Why The Milky Turquoise Waters?

Phytoplankton, NASA reported in a statement, are microscopic floating organisms making their own food from sunlight as well as dissolved nutrients. They generally support fish, shellfish, along with other marine creatures.

When these blooms occur too frequently or widely, they may result in eutrophication or the loss of oxygen from the water. Low oxygen levels in water can lead to die-offs among marine life.

The milky coloration, NASA added, is likely brought about by a specific phytoplankton growth, particularly of a coccolithophore. Emiliania huxleyi, a coccolithophore species, is a mono-celled organism that can adapt and thrive in waters spanning from the equator to the sub-Arctic region.

This specific organism is white calcium carbonate-plated. When present in huge numbers, it tends to result in water with a milky sheen.

Last year, New Jersey beachgoers were surprised by the view of aquamarine waters when they were typically grayish along the shore. The ocean around South Jersey was shown by NASA satellite photos to take on a greenish shade due to phytoplankton bloom, with the microorganisms visible along the Long Beach Island coast to Cape May.

Greening Of Arctic Ice

Recently, the greening of Arctic ice was exposed as a fallout of the massive phytoplankton bloom under the sea.

It’s blamed on no less than global warming. There is a humungous erosion of area covered under sea ice, and sea ice is heavily thinning today. Strong sea ice cover used to serve as a buffer against sunlight reaching the water below, protecting against plankton growth.

With progressive Arctic ice loss over the years and decades, sea ice color is also undergoing changes, going from white to darker hues as more sunlight penetrate the water beneath.

In the Arctic food web, phytoplankton is the significant base, and their growth draws in more fish and large predation. This paves the way for more food for local Arctic communities.