Non-biting midges (Diptera: Chironomidae) from fountains of two European cities: micro-scale island biogeography

We studied chironomid assemblages of 12 fountains located in Olomouc (Czech Republic) and in Copenhagen (Denmark). In total, 45 taxa of three subfamilies were recorded. The typical fountain assemblage was constituted of common species with very wide geographical distribution and ecological requirements as Cricotopus ornatus, C. sylvestris, Orthocladius fuscimanus, Psectrocladius limbatellus, Chironomus spp., along with tap-water species (Paratanytarsus grimmii), hygropetric and semi-terrestrial taxa (e. g. Orthocladius fuscimanus, Metriocnemus eurynotus). There was no linkage between taxa richness and fountain area or distance from the colonisation source. However, in Olomouc, with a single main colonisation source, a strong correlation between similarity of chironomid assemblage structures and distance to river was recognised. In Copenhagen, with a number of small water bodies, fountains were not correlated significantly with distance to sources. However, similarities of chironomid assemblage structures were negatively correlated with their geographical distances. Species temperature optima and preferences did not relate to distribution patterns. Generally, distance to natural aquatic sources, fountain proximity and regional factors determine the taxonomic composition of the non-biting midges.