Concentrations of Biogenic Compounds in Forest-Steppe Water Bodies and Streams Inhabited by Beavers (Сastor fiber L.)

Abstract

The aim of the study is to assess concentrations of compounds of biogenic elements (nitrates, nitrites, ammonium, and phosphates) and to analyze their distribution in water bodies and watercourses of the forest-steppe, where beavers were reintroduced recently. The study was carried out in the State Nature Reserve Privolzhskaya Lesostep’ (Penza oblast). We studied beaver ponds, oxbows inhabited by beavers, and also uninhabited streams. The concentrations of biogenic compounds in water were measured twice a year at the beginning and the end of summer. The results showed that, in general, all water bodies were characterized by an excess of threshold limit value (TLV) of concentrations for ammonium (TLV 2 mg/L, an excess in 76% samples) and phosphates (TLV 3.5 mg/L, 64%). Excesses were less common for nitrites (TLV 3.3 mg/L, 28%) and quite occasional for nitrates (TLV 45 mg/L, 2%). Moreover, the differences between the concentrations of biogenic compounds in the water bodies inhabited by beavers and uninhabited waters did not have statistical significance. Significant differences were observed only for different types of water bodies, which was associated with their water regime. The presence or absence of beavers, as well as their density and abundance, did not lead to significant changes in the concentrations of nutrients. The studied water bodies were surrounded by territories with a high level of agricultural impact, and under these conditions, the effect of beavers on the concentration of nutrients was not observed.