Aquatic biodiversity in Europe: a unique dataset on the distribution of Trichoptera species with important implications for conservation

Abstract

Freshwater ecosystems are known to harbour a rich diversity of habitats and species, but knowledge on the actual distribution of many species still remains scattered or unknown. Supported through the BioFresh project, we collected occurrence records of the insect order Trichoptera throughout Europe. By addressing 82 caddisfly experts, we compiled over 600,000 georeferenced occurrence records, 441,000 of which represent adult specimens. We evaluated the dataset regarding the caddisfly distribution based on freshwater ecoregions. This analysis reveals areas with high Trichoptera biodiversity and centres of endemism in southern Europe (e.g. Spain, Italy and the Balkans) as well as in mountainous regions (e.g. Alps). Also, data-deficient regions become obvious. This is either caused by missing experts providing occurrence records or by the inability to mobilise experts and their data of a certain region. Still, the database ranks among the most comprehensive actual distribution data collections of freshwater invertebrates. The database represents a highly valuable information source for a variety of macro-ecological analyses and modelling scenarios, and it could be the base for a European-wide IUCN Red List of threatened caddisfly species that supports conservation policy decisions.