| Popis |
In the north-western part of the Czech Republic, post-industrial sites created after brown coal mining represent habitats of specific environmental conditions which are missing in the surrounding agricultural landscape. These extensive spoil heaps are remarkable for their creation of unique aquatic biotopes; brooks and wetlands with a calcium carbonate (tufa) precipitation, conductivity up to 9,000 µS.cm-1 and high concentrations of sulphates, calcium, sodium, toxic metals such as iron and other ions which are a product of the specific bedrock of the Sokolov lignite basin. Although some taxa of invertebrates (terrestrial or adult stages of aquatic insects) have been studied thoroughly, benthic fauna of spoil heaps is almost unknown. Therefore, our research was focused on aquatic macroinvertebrates in three calcareous brooks. In total, 35 samples were collected in the seasons of spring and autumn in 2013/2014 and 222 taxa of macroinvertebrates (Clitellata, Coleoptera, Diptera, Ephemeroptera, Heteroptera, Mollusca, Odonata, Plecoptera, Trichoptera) were recorded. Notably, the order Diptera was found to be the most diverse, especially the family Chironomidae. Altogether, 45 taxa representing 5 subfamilies of non-biting midges (Chironominae, Diamesinae, Orthocladiinae, Prodiamesinae and Tanypodinae) were recorded. The most species-rich subfamily was Orthocladiinae, the most abundant subfamily was Tanypodinae. The chironomid assemblages included a high number of crenophilous and crenobiont taxa (e.g. Diamesa cf. insignipes Kieffer, 1908, Krenopelopia sp.) and lotic and lentic taxa (e.g. Eukiefferiella gracei gr., Procladius (Holotanypus) sp.). Semi-terrestrial and terrestrial taxa (e.g. Limnophyes sp., Smittia sp.) were recorded as well. Moreover, we also recorded wetland specialists (e.g. Metriocnemus eurynotus gr., Paratendipes nudisquama (Edwards, 1929)) and even a taxon occurring primarily in limestone rich waters (Neozavrelia sp.). Additionally, the comparison with the chironomid assemblage inhabiting natural brooks with tufa precipitation in the Bílé potoky Nature Reserve in the Western Carpathians showed similar taxa composition of non-biting midges as in the post-mining habitats. Conclusively, despite extreme environmental conditions and human activities, our research indicates that brooks with tufa precipitation in Sokolov spoil heaps are important biotopes and refuges for a high number of non-biting midges and also for other taxa of macroinvertebrates. This research was supported by MUNI/A/1362/2016.
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