Characteristics of caddis larvae assemblages from shallow lakes in the Bükk Mountains, North Hungary

Abstract

Seventeen caddisfly species of four families (Limnephilidae, Sericostomatidae, Phryganeidae, and Leptoceridae) with a total of 1047 individuals were collected from four sampling sites in the littoral zone of Disznóskút Lakes in the Bükk Mountains. Three of these four families of Trichoptera were also recorded in the Central European lakes. From among the four substrates (sand, silt, large stones, and aquatic plants) of the littoral zone, silt and aquatic plants were dominant. Besides species of Limnephilidae found in higher than the average abundance in the silt, species of Phryganeidae and Leptoceridae also occurred. The trophic relationships of the species of these families can be considered as follows: shredders- predators- scrapers, shredders- detritivores- predators, and predators- shredders- scrapers. From the aquatic plants the species of Limnephilidae, Phryganeidae and Leptoceridae, belonging to the trophic relationships of detritivores- shredders, scrapers- predators, shredders- detritivores- predators, and predators- shredders- scrapers- detritivores were collected. The analysis (PCA) of the spatial and seasonal distribution of Trichopteran larvae at the four littoral zone sites shows that the assemblages collected near the inflow of the stream into the lake in late summer and near the inflow of the small channel into the lake in summer are very different from the others, for which Limnephilus elegans, Micropterna lateralis, and Stenophylax permistus are responsible at the previous site, while Halesus digitatus, Halesus tessellatus, and Mystacides nigra are responsible at the latter one. The other assemblages (mostly those in winter) are very similar to each other, which can be explained by the decreasing number of detectable species and their presence in low abundance. For the variance, Limnephilus rhombicus (57%) and Potamophylax nigricornis (16%) are essentially responsible. Considering the species composition of the larval assemblages, the site at the inflow of the stream into the lake was the most different (38%) from the others, and was 62% similar to them. This dissimilarity can possibly be explained by the presence of a mixed assemblage with typical stream and lake inhabitants of species of Limnephilidae present in high abundance at this silt dominated site and other caddis species that are typical stream inhabitants or common in streams and small rivers, and may have drifted into the lake.