Caddisflies (Trichoptera) of Protected Calcareous Fen Habitats: Assemblages, Environmental Drivers, Indicator Species, and Conservation Issues

Simple Summary Calcareous fens, a unique and endangered type of peatland, harbour unique groups of little-studied aquatic insects. Caddisflies (Trichoptera), an amphibiotic insect group, have proven to be useful (at different levels of organisation) in describing various aspects of fens and their water bodies (pools and ditches). We focused on the evaluation of indicator species and the most important patterns and drivers of species distribution. A comprehensive approach including species, assemblages, functional groups, and ecological indices was recommended. In general, our findings provide a solid basis for analysing the potential of caddisflies in such habitats and present some useful tips for conservation practices and the management of these vulnerable ecosystems.Abstract The caddisflies (Trichoptera) of calcareous fen habitats, in contrast to those of other peatland types, have been poorly researched. We thus conducted a two-year study in south-eastern Poland encompassing four types of such habitats-drained and undrained fens and water bodies (pools and ditches) located within the fens-in order to define trichopteran reference assemblages (PCoA), indicator species (IndVal analysis), and the drivers (both natural and those associated with landscape management, including area protection) responsible for caddisfly species distribution (CCA). The most important environmental driver was habitat persistence. Distance-based RDA analysis revealed a distinct pattern in the distribution of species with or without diapause along the persistence gradient. Environmental drivers associated with plants were also crucial for both fens and water bodies. The key factor influencing the caddisfly assemblages of pools and ditches was the use and management of the surrounding land, whereas in the fens, it was the level of area protection. Physical and chemical water parameters had no statistically significant impact on the assemblages. Some factors can be modified by humans (e.g., water level regulation, vegetation, and landscape management) to maintain healthy ecosystems for aquatic insects.

Automated summary

Calcareous fens, a unique and endangered type of peatland, contain little-studied aquatic insects called caddisflies. This study focused on evaluating caddisfly indicator species and the drivers of their distribution in different habitats within calcareous fen ecosystems. The study found that habitat persistence, landscape management, and plant-related factors were important drivers of caddisfly species distribution. Physical and chemical water parameters were found to have no significant impact. The findings provide valuable insights for conservation practices and management of these vulnerable ecosystems.