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Abstract:
Quantitative samples of emerging Ephemeroptera, Plecoptera and Trichoptera (EPT-Emergenz) in the Breitenbach/Hesse have been collected in a trap (green-house) since 1969 (Illies 1971). Three additional green-houses were installed in 1974 and a fifth in 1977, sampling a stretch of ca. 300 m of the Breitenbach. The total catches from this series of five traps (Haus I -- V) are discussed. The dominating species Baetis vernus despite considerable local variations, reveals an even distribution within this stretch and each local value reflects the annual abundance of the species. The effectiveness and reliability of the emergence-method concentrating on catches from one trap is strongly confirmed by these similar values from different traps. Considering the whole EPT-emergence a great variety of patterns of abundance appears: some species show increasing upstream abundance, others tend to increase downstream and some occur exclusively in the downstream traps III, IV and V.
