Locals added a small dam to this natural depression, creating two smaller ponds connected by a strait. Since they could never be properly drained and were shaded by a forest, they were left unmanaged.
Today, the dam is underwater and Ledviny is once again a lake. Its name comes from the Czech word for “kidneys” because the lake is shaped like one. The name doesn’t appear in the scientific literature, however, but is widely used by the people who live in the area.
In terms of species diversity, Ledviny is the most interesting section of the set of plots. The lake’s water is dark yet surprisingly clear. Most of its surface is overgrown with floating pondweed in the summer while inconspicuous but increasingly rare dwarf pondweed grows below the surface.
The most valuable section of the site. Although described as a cascade of ponds in Jakubov, Ledviny is actually a lake. Based on the shape of the slope above and below it, a landslide of volcanic rocks must have occurred sometime in the past. This formed a natural depression that was later filled with water.
Among the species that thrive there, we can name three Czech newt species, the common frog, the common toad, and the marsh frog.
The flagship species of this site is the crucian carp.
This species is currently one of our most endangered native fish and was listed as critically endangered on the Red List of Endangered Species in 2017. A genetic study, which should confirm whether this species is a descendant of its originator, is being conducted by RNDr. Lukáš Choleva, Ph.D., from the Institute of Animal Physiology and Genetics of the Czech Academy of Sciences.
Other fish species that live in Ledviny include bream, perch and, to a lesser extent, tench.