Driftemergenz-Fanggeräte zur Erfassung schlüpfender Fließgewässer-Insekten (Ephemeroptera, Plecoptera, Trichoptera, Diptera)

Abstract

Almost all hitherto traps designed for recording the emergence of running waters not only catch in various proportions emerging insects drifted in from above but also such who directly emerge from the benthal region covered over by the trap. This also holds true for the Illies' emergence-house.- Hence, a new constructed device is offered which prohibits mixed catches of undefinable origin but exclusively takes in drift-emergence from an upper water layer of determinable thickness. An essential part of this device is a sieve-like plate which shields its interior from the benthal, but also can with its one end be let into the water body at determinable depths by changing its angle of inclination in relation to the water surface. From the hereby given width of the inflow opening and the speed of the water current the amount of water flow per time unit is to be calculated, thus giving a reference base for the qualitative and quantitative evaluation of the corresponding sample. There are 3 different versions of the new design which can be applied according to location, size and structure of the to be investigated running-water, and for basic research as well as for longtime monitoring of water pollution and environmental assessments.