State environmental officials said Thursday that the water level at Lake Koroneia has dropped by more than 70% percent in the past three years, to 80 centimeters (31 inches), with the decline triggering the death of carp, sunfish, bleak and other freshwater fish.
Dimitra Bobori, an associate biology professor at the University of Thessaloniki and the lake's senior administrator, said dissolved oxygen concentrations in the water had fallen below a critical level, accelerating the deaths over the last week.
"Due to the high temperatures, the solubility of oxygen is limited in the body of water that is left," Bobori said. "We have sent samples of dead fish and water for toxicological testing, as high temperatures also give rise to toxicity levels."
Once one of Greece's largest lakes, Koroneia is 30 kilometers (18.5 miles) east of Greece's second-largest city Thessaloniki. Originally spanning 4,500 hectares (11,000 acres), it has shrunk to about a third of its original size over the past three decades.
The lake is part of the European Union's network of protected nature areas and Greek authorities have launched a long-term effort to try and prevent Koroneia from drying out, employing water diversions, temporary fishing bans, and a crackdown on the illegal disposal of industrial waste from nearby factories.
Water levels had stabilized at about three meters (10 feet) by 2015, but summers are getting longer and hotter. "Over the last 20 years, there is no doubt that the weather has become hotter in this region, and the trend is worsening," Prodromos Zanis, a professor of meteorology and climate science at the University of Thessaloniki, told The Associated Press.
"The frequency of this phenomenon makes it statistically likely that this is in part driven by manmade climate change." Villages on the banks of Koroneia and nearby Lake Volvi have seen their livelihoods hit by the receding water.
"There are thousands of dead fish near us and the smell is awful," said store owner Nikolaos Rossias, from the lakeside village of Agios Vassilis. "There used to be 10 fish restaurants in the village."
Now there is only one. "It feels like nobody cares about the lake ... so many fish have died and our wealth was destroyed."
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