Environmental factors associated with biodiversity and the occurrence of rare, threatened, thermophilous species of aquatic beetles in the anthropogenic ponds of the Masurian Lake District

Abstract

This paper presents the results of an analysis of species richness (expressed as number of species), biodiversity (the H′ index) and synecological structure of communities of aquatic beetles living in clay and gravel pits. It evaluates the analyzed habitats in terms of the influence of water physical and chemical parameters on the characteristics of beetle assemblages. The assessment of beetle communities was performed from the point of view of ecology and nature conservation. The analyzed physical and chemical parameters of water as well as the presence of certain species, mainly rheophiles, indicate very weak eutrophication of the ponds. The parameters which most significantly distinguish gravel pits from clay pits are specific conductivity, HCO3−, SO42− and Cl–. The PCA analysis, however, suggests that the abundance and species richness as well as the biodiversity of beetles living in the analyzed ponds were most closely correlated with temperature and with NH4-N, total N and the BOD5 of water. The analyzed ponds proved to be very attractive habitats populated by numerous species, including rare, threatened (listed in the Polish Red Book of Species) and termophilous ones, or organisms valuable to Polish wildlife for other reasons. They include two species rare in Poland—Hydrochus ignicollis and Ochthebius hungaricus, one species fully protected in Poland—Hydrophilus aterrimus (VU), as well as Haliplus fulvicollis (VU) and Gyrinus caspius (EN). The findings are important for the preservation of biodiversity, both locally and on a scale surpassing the region, a conclusion which highlights the value of anthropogenic ponds such as clay pits and gravel pits, in the ecological landscape and implies that they deserve an adequate protection in order to sustain their function.