A summer holiday mecca, particularly for tourists from Hungary’s capital Budapest 100 km away, over the last 20 years Hungary’s Lake Balaton has seen its water rise by 1.4 °C.
Although warm summers cause evaporation, and autumn and winter rain should replenish the water levels, climate change has led to lower rainfall in the off-season, resulting in a fall in the lake’s water level and a steady rise in water temperature.
Scientists now fear this could threaten to wipe out its 40 native types of fish as well as rare birds, including the black stork.
The researchers at HUN-REN Balaton Limnological Research Institute, quoted by the Hungary Today website, say that if the current trend of the average water temperature rising by 0.7°C per decade continues, as they expect it to, the effect on the native ecosystem could be devastating.
The scientists who study the ecology of inland bodies of water using historical satellite images and local measurements say the many rare types of flora and fauna could also be at risk.
The danger comes in the form of the spread of invasive species, which are better adapted to the warmer water temperatures.
These include algae, which are choking up part of the lake and starving fish of oxygen; mussels attached to boat hulls, which are now ensconced on the lake floor; and eels and bream.
Introduced by lake authorities before the lake was made a nature reserve in 1997, they have edged out the indigenous perch and tench.
Senior research fellow Viktor Tóth said that while the original residents of the Balaton can adapt, the pace of environmental change “can outstrip their ability to adapt.”
He added that a continuation of warming “could mean non-native species could become dominant.”
Fellow scientist Huan Li said: “Our preliminary work suggests that if climate change does not abate, we will see continued warming, meaning that in 10 to 20 years, water temperatures will continue to rise by 0.5 to 0.7°C per decade.”
