In Izmir's Karşıyaka district in western Anatolia, the sea has taken on a striking green hue, while in Balçova district, it has turned a troubling shade of brown. This sudden change in color has left residents bewildered, and an unpleasant odor has permeated the area.

Professor Doğan Yaşar, a member of the Türkiye Academy of Sciences (TÜBA) Environmental, Biodiversity and Climate Change Working Group, attributed this phenomenon to recent temperature spikes leading to plankton blooms.

"Due to these plankton blooms, the water around Karşıyaka turned green, while Çakalburnu Dalyanı in Balçova district turned brown. Pollution also contributes significantly to this color change," Yaşar said.

He highlighted a worrying trend of environmental neglect over recent decades, saying: "After 2007, pollution intensified with the concreting of streambeds and closure of treatment plants in factories. By 2011-2012, the gulf began emitting foul odors reminiscent of conditions prior to 2000. Last year, we even witnessed mass fish deaths as a consequence."

Reflecting on past efforts, Yaşar recalled: "During the tenure of former Izmir Metropolitan Municipality Mayor Ahmet Piriştina, significant efforts were made to combat sea pollution. However, subsequent administrations neglected these efforts. In the mid-2000s, optimism prevailed that we would soon swim again in cleaner waters around Göztepe and Güzelyalı, where the gulf had noticeably turned blue. Unfortunately, this momentum was not sustained."

"Each liter of seawater contains approximately 1 million organisms. With increasing temperatures and pollution, this number rises to around 2 million in seawater. When they reach 2 million, they consume all the oxygen in the environment and die. Sometimes, you see blue, green, reddish or whitish colors. These colors vary depending on the types of plankton; thus, these colors are due to the dead plankton," said Yaşar.

"Unfortunately, one of the biggest problems in our country right now is using seas as septic tanks. In Turkey's seas, there was a tremendous plankton bloom for the first time in 1955 in Izmir's inner bay. As a result, thousands of fish died," he added.

The expert concluded with a call to action, emphasizing the need for clean water inflows and removing concrete obstructions from the gulf's streams: "These measures are essential to restore ecological balance and safeguard our marine biodiversity."