Abstract
All over the world, comprehensive data on aquatic communities are collected in the course of applied investigations (e.g. environmental impact assessments for road or railway construction projects, assessments of wastewater treatment plants, hydropower plants, etc.). At the same, little is known about certain endangered or rare species, their distribution or their actual conservation status, as the data collected in applied projects are usually not published. It can be stated that applied investigations would offer valuable information on the distribution of endangered species if there was sufficient data interchange within or data transfer to the scientific community. This thesis is supported by the fact that the authors were able to demonstrate that 72 caddisfly species that are quoted in the Austrian Red List in the course of applied investigations in Austria, but that none of the data have been published so far. The present study provides a list of endangered Trichoptera species that were observed by the authors in the context of routine surveys over the past five years. It is intended thus to provide an example of how data that could be relevant for obtaining a comprehensive picture of certain species are often lost on their way to publication.