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Abstract
Records of species composition, specimen numbers and biomass of adult water-insects (Ephemeroptera, Trichoptera, Plecoptera) emerging from about 10 m2 of a small stream (Breitenbach, Hassia) are presented for the years 1969-1976 (Tab. 1-3). Constancy of species composition, abundance of common species and fluctuation of total weight are discussed. Total weight is mainly determined by few common species (Tab. 4 and fig. 1). The 3 most common ones contributing 51 % of total weight. Discussion of predation, fluctuation of water level (fig. 2), temperature and substrate reveal the great importance of local changes in substrate-pattern, while the other factors are of comparatively low significance for the general trend of production in individual years.
