The rivers in Central Europe are warming. As a result, trout are dying out
Fishermen in Central Europe are warning of the shrinking population of the river trout. The populations of this fish are significantly decreasing, especially in the lower parts of rivers. The fact that trout is disappearing from its rivers as a result of warming was confirmed by a recently published study by the World Wildlife Fund.
Trout needs very specific living conditions. The flow must be sufficiently rich in nutrients and its acidity must be at the proper level. In addition, rivers must have sufficient currents and appropriate shelters. However, the water temperature is key, i.e., from 14 to 17 °C.
However, due to global warming, the temperature of the water in the Elbe, Vltava, Danube, and other Central European rivers will rise by up to 1.5 degrees by 2050. Warmer water will complicate the life of indigenous fish and aquatic plants, which may be pushed out by their more resistant competitors introduced into European rivers from other parts of the planet.
During the 20th century, the water in Czech, German, and Austrian rivers warmed by about one degree. Due to the rising water temperature, trout populations are also slowly decreasing in mountain creeks and streams. Trout are extremely sensitive even to the minimal changes in water quality and temperature.
As the temperature rises, the susceptibility of aquatic animals to various epidemics and diseases increases. Massive eel mortality was identified by scientists, for example, in the excessively warmed waters of the Rhine in the summer of 2003.
“Rivers are a key source of life in Europe’s landscape. Their disruption by global climate change will have far-reaching consequences for people’s lives and biodiversity. Reducing greenhouse gas emissions thus greatly helps protect the European landscape in the form we know and love,” commented Director Dalibor Dostál of the European Wildlife conservation organisation.
Paradoxically, the reason for the rise in temperatures may also be the construction of wastewater treatment plants to treat water from households and industrial facilities. Nature conservationists say the treatment plants release much warmer water back into rivers than they receive.
Photo: Aaron Gustafson / Wikimedia
