TEKIRDAG, Türkiye

Climate change has not only led to record-breaking heat on land but sea as well, a development that has led marine creatures to change their habitats, according to an expert.

Deniz Sirin, biology professor at the Tekirdag Namik Kemal University in Türkiye, told Anadolu that sea water temperatures have increased by approximately 1.5 degrees Celsius in the Mediterranean and 0.5 degrees in the Black Sea in the last 100 years, and the change is causing deterioration of the marine ecosystem.

Sirin said the distribution and life cycles of some fish species have changed as they have become more susceptible to diseases.

“The Turkish Marine Research Foundation's report on climate change and seas contains striking examples," he said, explaining that the presence of species such as sardines, bogues and salema, which live in the Mediterranean and were rare in the Black Sea and Marmara two decades ago, can be attributed to the rise in sea temperatures.

The emergence of sunfish from the south of the Mediterranean to the Marmara Sea, as well as sea urchins, which are invertebrate, in the North Aegean and Marmara Sea is also due to effects of global warming, he said.

Sirin said species suitable for living in the Mediterranean began to gradually spread to the Northern Aegean, Marmara and even the Black Sea as the water warmed.

The expert said the increase in sea temperature also causes algal blooms, bringing adverse effects on aquatic organisms.

“Algal blooms occur when substances such as nitrogen or phosphorus enter the water system, causing excessive algae growth," he said, adding that it blocks sunlight and decreases the level of oxygen, making difficult for aquatic life to survive.

Toxic algae blooms were blamed for recent deaths of sea lions and dolphins along the coast of California's southern beaches. It is believed that small creatures such as shellfish consume the toxins before being eaten by larger marine mammals, who then become toxified themselves.