Materials to the knowledge of the aquatic beetle fauna (Coleoptera) in mid-western Poland (Lubuskie Province)

Abstract

Although aquatic beetles are one of the most diverse groups significantly contributing to species diversity in freshwaters, their occurrence and distribution has been studied very poorly in mid-western Poland. Consequently, our knowledge about the current aquatic beetle species richness and habitat preferences is still scarce in large parts of this region. To close this knowledge gap, we investigated a selected area of approximately 500 km2 in the south-western part of the Lubuskie Province, part of the Wielkopolsko-Kujawska Lowland, to obtain the richness of total, protected, endangered and rare species of aquatic beetles, as well as to analyse their diversity and ecological groups in representative habitats. For the study, 70 sampling sites representing ditches (5 localities), streams (4), rivers (13), small water bodies in open landscapes (7) and in forests (6), temporary (8) and permanent (7) fish ponds, lakes (4), fens (1), peat bogs (13) and marshes (2) were investigated from April to September 2011. In total, 115 species, including 10 protected by law or/and listed on the Polish Red List, as well as 11 rare and local in Poland species were found in the study area. Among them special attention should be paid to Macroplea appendiculata – a recently-discovered for the Wielkopolsko-Kujawska Lowland and critically endangered in Poland species as well as Rhantus incognitus – an endangered and rare species in Poland. The most frequent species was Hyphydrus ovatus (34.3% of sites), whereas 29 species, mostly stenotopic specialists, were recorded in only one site. Eurytopes and tyrphophiles were both present in each habitat type. Further, the most diverse habitats were temporary ponds containing 7 groups of stenotopes, whereas in streams only 2 groups were found. On average, the most species rich habitats were permanent ponds (median = 11 species) and bogs (11), but the highest species numbers were found in a temporary pond (44 species) and in a small water body in open landscape (42). The lowest species richness was found in streams (maximum
4 species per site). According to an evaluation of habitat types based on protected, threatened and rare species, the most important were permanent and temporary ponds in the forested, water-rich parts of the study area. In agriculturally dominated parts, however, small rivers and occasionally small water bodies were of high importance for rare species.
We conclude that the species richness and abundance of protected, endangered and rare species are high in the study area in comparison to other parts of Poland. The most important habitats in terms of high diversity of aquatic beetles are predominantly permanent fish ponds and bogs, whereas permanent and temporary fish ponds play a key role for the high content of rare and protected species
in the area.