“Sand pits are becoming oases full of life in a man-influenced landscape. Many species formerly inhabiting ponds, ponds or dead branches of rivers began to secondary colonize ponds in sand pits. There are several reasons. Above all, however, the ponds in the sand pits are poor in nutrients and mostly fish do not live in them. This suits a wide range of animals from amphibians and reptiles to aquatic insects, “said Jiří Řehounek from the Calla association.
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According to him, in the sand pits, everyone can see not only relatively common species, but also rare and endangered animals, which are quickly disappearing from the landscape.
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“Aquatic animals have a hard time in today’s landscape. Intensive fish farming in ponds, gradual grounding and extinction of blind branches, regulation of watercourses or the spread of non-native fish species deprives them of the natural environment, “said Vojtěch Kolář from the Faculty of Science of the University of South Bohemia and the Biological Center of the ASCR.
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Scientists and conservationists are investigating sand pits in the Tábor, Třeboň and České Budějovice regions. Most of them undergo interventions from time to time to support endangered species, especially the restoration or creation of ponds. They want to evaluate the success of these interventions and plan further care for scientifically valuable sand pits accordingly. Preliminary results of the project already suggest that the potential of these small ponds for nature protection is great.
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“During the surveys, we found three species of newt – the newt, the newt and the great newt, ie all South Bohemian species. One of our largest water beetles, the dark water beetle, as well as small endangered beetles, the water beetle Chaetarthria seminulum and the diver Bidessus grossepunctatus, live in the ponds, ”said Vojtěch Kolář, who is in charge of biological research.
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“The latter species is a bioindicator of preserved habitats and occurs mostly on peat bogs, we found it in two sand pits. It is known in our territory only from a few places in the Třeboň region. On the contrary, the mentioned small water meter needs an open substrate with sparse vegetation at the transition of water and land. Peat dragonflies, such as the white-mouthed dragonfly or the dashed dragonfly, are also typical for sand pits overgrown with peat, ”he added.
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If we leave the ponds in the sand pits only to natural processes, they begin to overgrow with vegetation, are filled with leaves and other material from the surroundings and gradually dry out. “Aquatic animals gradually disappear from such ponds. That is why conservationists are carrying out interventions, such as the restoration of ponds or the carving of overgrowth trees in their vicinity, ”explained Řehounek, adding that Calla has long taken care of several naturally valuable sand pits.
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“We must also appeal to our fellow citizens not to spread non-native species of plants and animals, such as American catfish, silver carp or water lilies, to these biologically valuable sites. The introduction of these non-native species is not only illegal, but above all it can cause irreparable damage to aquatic insects or amphibians, “concluded Vojtěch Kolář.
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