Long-term studies on aquatic Dance Flies (Diptera, Empididae) 1983-1993: Distribution and size patterns along the stream, abundance changes between years and the influence of environmental factors on the community

摘要: Twenty nine species of aquatic dance flies (Empididae: Clinocerinae and Hemerodromiinae) were recorded from the Breitenbach (Hesse, Germany) between 1983 1993. Although most emerged in spring summer, Clinocera (Hydrodromia) stagnalis C. (H.) wesmaeli trapped almost every month. A few subgenus Kowarzia autumn early winter. Chelifera pyrenaica had two generations per year lower part stream, but upper reach there was only a generation. The distribution pattern along stream abundant maintained over entire study period. As an exception, Wiedemannia bohemani middle 1983-1988, 1989-1993. amount Particulate Organic Matter (POM) probably increased abundance prey organisms, highest numbers found areas with high amounts allochthonous input. Larvae avoided sandy substrates. Many partly submerged moss carpets on stones, at or below water level. Females Hemerodromiinae higher body weights than males, specimens localities near heavier those sections as result temperature stream. In differences sexes, different sites, negligible. Ordination data, well environmental showed dominating influence 'time' discharge community flies, subordinate temperature, time series 11 years.