Impact of beaver (Castor fiber) activity on chemical composition of water and sediment in Polish and Slovakian Carpathian rivers – preliminary studies

European beaver (Castor fiber) significantly affects hydrogeomorphological processes, mostly due to its ability to build and maintain dams on rivers. Changes in flow regime, water storage and rates of sediment deposition lead to alterations in chemical composition of water and accumulated material. Recent findings suggest that beaver dams can be considered as a factor in river self-cleaning process in European lowlands (Puttock et al., 2017).

In order to examine beaver impact on mountainous rivers along a N-S transect through the Western Carpathians, selected sections of river valleys from the foothills through the Beskids in Poland to the southern slope of the Western Carpathians in Slovakia were surveyed. Study was conducted on 21 sites on 19 rivers. Each site consisted of three sampling points: above and below the beaver cascade or pond (if there was only one) and by the largest dam in the system. Water samples were taken in the summer and autumn of 2022, at normal water levels, and sediment samples were taken during field surveys in the autumn of 2022. The heavy metal content in sediments and the ionic composition in water  were determined using an ICP MS TOF spectrometer (Optimass 9500 GBC) and  Dionex ICS3000 ion chromatograph.

Beaver populations considerably increased in Western Carpathians in recent years and their contemporary occurrence is relatively new in the area where they were extirpated probably ca. 400 years ago (Żurowski, 1986). Reintroduction program was conducted in some Carpathian catchments in Poland in the 2nd part of the XX century (Kasperczyk, 1987). Release sites acted as dispersion centers not only for Polish but also Slovak populations in the analyzed mountain range. High migration rates and inhabitation of various habitats (from semi-natural to highly anthropogenically modified) catchments makes the research on this ecosystem engineer in Carpathians particularly important.

This study covers preliminary results of the Polish National Science Centre PRELUDIUM BIS 2 research project No. 2020/39/O/ST10/01354, entitled "Impact of European beaver (Castor fiber L.) activity on the environment and human economy along the N-S transect through the Western Carpathians (Poland-Slovakia)".

References

Kasperczyk B. (1987). Rozprzestrzenianie się bobra europejskiego (Castor fiber L.) w Europie w XX wieku. Przegląd Zoologiczny 31(2), 181-193. (in Polish)

Puttock A., Graham H. A., Cunliffe A. M., Elliott M., Brazier R. E. (2017). Eurasian beaver activity increases water storage, attenuates flow and mitigates diffuse pollution from intensively‐managed grasslands. Science of the Total Environment, 576, 430–443. 10.1016/j.scitotenv.2016.10.122 

Żurowski W. (1986). Bobry w górach. Przyroda Polska, 6, 10-11. (in Polish)