Stanisław Czachorowski

Water mites (Acari, Hydrachnidia) of water bodies of the Krąpiel River valley: interactions in the spatial arrangement of a river valley

The present study is a discussion of the interactions between different types of water bodies in the spatial arrangement of a river valley, taking into account landscape data. The Hydrachnidia assemblages in particular types of valley water bodies (oxbows, riparian pools, permanent ponds, flooded alder carrs, sedge marshes, and springs) are strongly influenced by the spatial arrangement of the water bodies in the landscape. Moreover, the formation of a fauna in a particular type of valley water body is also influenced by its origin. For example, the faunas of the oxbow lakes and riparian pools would have many characteristics in common, as these two types of water body can be characterized as originating in the river. As many as 61 species common to the valley water bodies and the Krąpiel River were noted. In the interactions between the valley water bodies and the river, the direction of migration from the former to the latter was clearly predominant. Migration in the reverse direction, from the river to the valley water bodies, took place to a far lesser degree. CCA analysis of landscape variables showed the influences of certain landscape parameters on water mites. These should be regarded as indirect influences, but as a consequence of their effects, they influence the formation of specific types of Hydrachnidia assemblages.

Early post-dredging recolonization of caddisflies (Insecta: Trichoptera) in a small lowland river (NW Poland)

An analysis was made of the effect of dredging on the caddisfly fauna (Trichoptera) of the river Krąpiel (north-western Poland) a short time after the intervention. Pronounced changes were observed in the qualitative and quantitative structure and the biodiversity of Trichoptera. These changes should not, however, be characterized as unfavourable from an ecological perspective if we consider only the one group of insects analysed. Some species — Brachycentrus subnubilus and Lepidostoma hirtum — disappeared from the dredged parts of the river, but significantly more appeared, and these were typical river species. This replacement of species can be linked to habitat changes and the uncovering of larger patches of sandy bottom. The recolonizing species included accidental (eurytopic) species, which is typical in ecological succession for periods immediately following disturbances. On balance, despite the replacement of species, there was no decrease in species diversity, and typical river species appeared in larger numbers. In Trichoptera, recolonization following dredging first takes place as a result of drift of larvae, and then via dispersion of adults.

The influence of environmental factors on water mite assemblages (Acari, Hydrachnidia) in a small lowland river: an analysis at different levels of organization of the environment

Research on the ecology of water mites in flowing water has focused mainly on analysis of factors directly affecting these organisms in the aquatic environment. The hypothesis of this study was that apart from factors acting within the aquatic environment, the formation of Hydrachnidia communities in lotic ecosystems may also be affected by factors acting in the terrestrial environment. The analysis was made at three different levels of organization of the environment: (1) landscape level (sub-catchments, terrestrial environment), (2) macrohabitat level (sampling sites, aquatic environment) and (3) mesohabitat level (sampling sub-sites, aquatic environment). Some correlation was noted between certain species and some sub-catchment parameters. This may indicate a link between some landscape features (terrestrial environment) and the formation of water mite assemblages in the river. The low percentage for physicochemical parameters together in explaining the variance in occurrence of species, very low correlations between species and physicochemical parameters and the discrepancy in the grouping of sites in the case of faunal data and data on the physicochemical indicates that physicochemical factors had little influence on water mites. Taking into account all three levels of organization of the environment analyzed, we can say that at the landscape level we can find only indirect relationships between environmental factors and the fauna inhabiting the aquatic environment; at the macrohabitat level the description of Hydrachnidia is more precise but still of a general nature. Only analysis at the mesohabitat level fully explains the specific character of Hydrachnidia assemblages.

Are beetles good indicators of insect diversity in freshwater lakes

Abstract The study verifies the usefulness of aquatic beetles as an indicator of biodiversity of a simple ecological system. Detailed analyses were carried out at the elementary level for the purpose of determining the significance of correlations between the biodiversity of Coleoptera and other groups of aquatic insects in single samples. The relation of selected taxa to selected habitats of the lake Wukśniki (north-eastern Poland) was also investigated. Moreover, the possibility of application of biodiversity surrogates, i.e. higher taxonomic units (genera and orders), in the determination of biodiversity was examined. A significant high correlation was determined between Coleoptera and the total remaining taxa (RR - Remaining Richness) in samples collected in the entire lake. The correlation has the highest value at the species level. The complementarity analysis reveals that the percentage contribution of Coleoptera in the overall biodiversity of the lake is similarly high at the species and genus level, and substantially lower at the family level. In accordance with the hypothesis, aquatic beetles can be used as indicators of the overall biodiversity of insects in the ecosystem of a mesotrophic lake. Biodiversity surrogates, i.e. higher taxonomic units (genera and families), can be applied instead of the species level.

Aquatic Insects (Insecta: Plecoptera, Ephemeroptera, Odonata, and Trichoptera) of the Rivers in the Berezinskii Biosphere Reserve

The fauna of aquatic insects was studied in the rivers of the Berezinskii Biosphere Reserve. A total of 108 species of 4 orders were found: Plecoptera (10 species), Ephemeroptera (24), Odonata (25), and Trichoptera (49). The aquatic fauna is abundant and includes some species rare in Belarus and Europe.

Human impact on large rivers: the influence of groynes of the River Oder on larval assemblages of caddisflies (Trichoptera)

The influence of groynes in large rivers on caddisflies has been poorly studied in the literature. Therefore, we carried out an investigation on the 420-km stretch of the River Oder equipped with groynes. At 29 stations, we caught caddisflies in four habitats: current sites, groyne fields, riverine control sites without groynes and in the river’s oxbows. We found that groyne construction increased species richness, diversity, evenness, and altered the structure of functional groups into more diversified and sustainable ones compared to the control sites. The groyne field fauna is similar to that of natural lentic habitats, but its composition is largely governed by the presence of potential colonists in the nearby oxbows. We distinguished three of the river’s caddisfly assemblages. The distribution of Trichoptera was governed inter alia by the plant cover and the amount of detritus, and consequently, the food resources. Oxygen, nitrates, phosphates and electrolytic conductivity were important as well. Groynes have had positive effects for caddisflies—not only those in the river itself, but also those in its valley. They can therefore be of significance in river restoration (although originally they served other purposes), especially with respect to the radically transformed ecosystems of large rivers.

Caddisflies (Trichoptera) of the protected territories of Belarus

The caddisfly fauna of 13 protected areas in Belarus is studied. A total of 97 species from the following 12 families are recorded: Hydroptilidae (6 species), Ecnomidae (1), Polycentropodidae (11), Pshychomyidae (1), Hydropsychidae (5), Phryganeidae (12), Brachycentridae (1), Limnephilidae (41), Sericostomatidae (1), Molannidae (1), Beraeidae (3), and Leptoceridae (14). Polycentropus kingi McLachlan, 1881; Agrypnia picta Kolenati, 1848; Limnephilus sericeus (Say, 1824); L. dispar McLachlan, 1875; L. elegans Curtis, 1834, and Hagenella clathrata (Kolenati, 1848) are rare in Europe. Some of the revealed species are critically endangered in several countries of western Europe. The studied protected areas play an important role in conservation of species diversity and in the distribution of several rare species.