Lake Balaton is warming up faster, which may lead to drastic changes in the lake's aquatic life

The ecosystem of Lake Balaton may become unbalanced, periods of oxygen depletion and the risk of algal blooms may increase, and heat-loving, invasive plant species may soon appear in the lake, as its water keeps getting warmer. According to an article in Másfélfok, in the past three decades, the temperature of the water of lake Balaton has increased three times as much as it did in the more than 120 years before that.

A study conducted by researchers at HUN-REN's Balaton Limnological Research Institute found that the water in Lake Balaton is now on average 1.7 °C warmer than in 2000, and the change is accelerating. Until the 1980s, the average annual temperature changed slowly, but since then this process has become faster, with the average increase in the 21st century reaching 0.07 °C per year.

Lake heatwaves are also becoming more frequent – these are periods when, for at least five days, the water is warmer than it was in the warmest 10% of days at the end of the 19th century. There can currently be more than 100 such days in a year. On these days, the temperature of the water can be up to 6 °C warmer than the previous climate norm.

"If the temperature of Lake Balaton continues to rise, it could create ecological conditions that more closely resemble those of the Mediterranean or even subtropical regions. In this new world, the aquatic plants of the future will not necessarily be the species we are familiar with today, but communities may develop that neither wildlife nor humans are accustomed to," the researchers write.
According to Másfélfok, as the water temperature rises, sharp-leaved aquatic plants that thrive in oxygen-depleted environments may begin to appear in Lake Balaton. These could include water milfoil and the great prickly seaweed, both of which can be very unpleasant for swimmers.

Péter Takács, senior research fellow at HUN-REN's Balaton Limnological Research Institute, told Telex back in 2024 that the further warming of Lake Balaton could have unforeseeable consequences. They have already produced a film (with English subtitles) about invasive species: