Critical warning from METU for the Mediterranean: Oxygen levels in the Gulf have dropped by half, 'We are in the middle of a bad scenario'

The "Mediterranean Monitoring Expedition", in which 14 scientists from METU Marine Sciences Institute participated, was held between 5-15 August. Within the scope of the expedition carried out throughout Türkiye's Mediterranean waters, the current state of the marine ecosystem was examined. Many parameters were examined, especially sea temperature, oxygen level, light transmittance, turbidity and pollution indicators.

Evaluating the first results of the expedition, Salihoğlu said that the pollutants carried from rivers and cities to the sea after heavy rains especially affected the inner parts of Mersin and İskenderun gulfs.

Emphasizing that marine pollution is not just about plastic, Salihoğlu stated that nitrogen and phosphorus loads from city wastes, rivers and widespread sources cause eutrophication in the seas.

Salihoğlu underlined that the sea turbidity was much higher than what he had measured so far in the last expedition and said, "The turbid water we saw showed that the sea turbidity was much higher than what we had measured so far. Light transmittance is very low. Algae proliferation is very high. This situation may cause harmful algae that may grow in the gulfs to pose a threat to human health." he said.

"IT IS VERY CONCERNING THAT THE OXYGEN DECREASE THIS MUCH"

Noting that one of the most striking results of the expedition was the decrease in oxygen in the sea, Salihoğlu continued his words as follows:

"While oxygen should normally be around 7 milligrams per liter in the bottom water in the Iskenderun and Mersin Gulfs, it has dropped to 4, halved, this is very striking. It gives serious signals, this decrease in oxygen is very worrying. We can say that as we go west, for example, in the Gulf of Antalya, water quality improves and oxygen deficiency is not observed. These regions have more dynamic sea conditions and circulation, but are also sensitive. Terrestrial inputs should be taken into consideration."

Stating that they also observed plastic pollution on the surface, Salihoğlu stated that they detected a slight increase in plastic pollution compared to past measurements, and that the final results will be revealed after laboratory studies.

Salihoğlu stated that the average sea water temperatures on Türkiye's Mediterranean coast in the open sea remained at the same values ​​as today, and that they even encountered cooler waters compared to 2024-2025, and that they encountered a different picture on the coasts.

Salihoğlu mentioned that the sea water temperature rises up to 32 degrees here, and evaluated that the effects of this change may be seen in the long term.

"WE HAVE COME TO THE BAD SCENARIO"

Pointing out that high temperatures change the sea structure and oxygen solubility, Salihoğlu said, "The acceleration of the breakdown of bacteria is an additional contribution to the decrease in oxygen. We think that the increase in pollution and the increase in temperature together cause this decrease in oxygen." he said.

Salihoğlu warned that the increase in pollution, the increase in water turbidity and the decrease in oxygen in recent years point to a worse situation, especially in the gulfs of the Mediterranean, and said, "Actually, we were saying that the situation up to now was giving danger signals. We were saying that this increase in pollution would lead to a worse scenario. I think we are in the middle of that scenario. This decrease in oxygen is what we were afraid of, so we have come to that bad scenario." he said.

Stating that the pollution in the sea has now exceeded tolerable levels, Salihoğlu stated that if the decrease in light transmittance and the decrease in oxygen levels continue, there may be effects on biodiversity, marine creatures and human health.

"FLOOD WATERS HAVE THE POTENTIAL TO CARRY VERY SERIOUS POLLUTION"

Referring to the impact of excessive rainfall on the marine ecosystem, Salihoğlu noted that extreme rainfall waves and floods have increased with climate change, and that these conditions can intensively carry pollution on land to the sea.