Biological indices applied to benthic macroinvertebrates at reference conditions of mountain streams in two ecoregions (Poland, the Slovak Republic)

The study was carried out from 2007 to 2010 in two ecoregions: the Carpathians and the Central Highlands. The objectives of our survey were to test the existing biological index metric based on benthic macroinvertebrates at reference conditions in the high- and mid-altitude mountain streams of two ecoregions according to the requirements of the EU WFD and to determine which environmental factors influence the distribution of benthic macroinvertebrates. Our results revealed statistically significant differences in the values of the physical and chemical parameters of water as well as the mean values of metrics between the types of streams at the sampling sites. RDA analysis showed that the temperature of the water, pH, conductivity, the stream gradient, values of the HQA index, and altitude were the parameters most associated with the distribution of benthic macroinvertebrate taxa and the values of the metrics. The values of biological indices should be considered according to the stream typology including altitude and geology. At the reference conditions, the suggested border values of biological indices are very harsh. The values of the biological indices of most sampling sites did not correspond to the requirements of the high status in rivers. The streams at altitudes above 1,200 m a.s.l. should be treated as another river type and new reference values should be established

CHANGES IN THE TROPHIC STATUS OF LAKE NIEPRUSZEWSKIE (POLAND)

The paper presents the evaluation of trophic status of Lake Niepruszewskie in the years 1994–2013. This is the first lake in the Samica Stęszewska river, flowing distally through the lakes of the Wielkopolski National Park. Source part of the Samica Stęszewska river basin was, in the years 2004–2012, included to the nitrate vulnerable zone (NVZ), and Niepruszewskie Lake was considered to be threatened by eutrophication. The evaluation of trophic status of the lake was made based on the concentration of nutrients (nitrogen and phosphorus) and indicators of eutrophication (chlorophyll a, water transparency Secchi disk marked) by referring them to the limit values for the eutrophication of surface waters as defined in the Regulation of the Minister of Environment of 23 December 2002 and other criteria used for the classification of the eutrophication of surface waters. Detailed and synthetic indexes of the trophic status (TSI) using the formula Carlson and the ratio of N:P were also made. Concentrations of the nutrients in Lake Niepruszewskie and eutrophication indexes reached high values, indicating a eutrophic or hypertrophic state of the lake. Detailed values of the trophic status index (TSI), on average over the period, corresponded to eutrophic, while in subsequent years they were varied – from mesotrophic to hypertrophic. The worst trophic status was recorded in 2003–2006, after the lowering of the lake damming. The high value of N: P ratio indicates that the lake has huge surplus of nitrogen, and phosphorus is a productivity limiting factor

Influence of selected environmental factors on macroinvertebrates in mountain streams

The objectives of our survey were: to analyze the structure of macroinvetebrate communities in mountain streams in national parks and Biosphere Reserves (Poland, the Slovak Republic), to determine the environmental factors that influence the structure of macroinvertebrate communities and to assess the stream habitats including the bank and channel features, any modifications, land use and channel vegetation. Our results showed that in addition to the conductivity, the altitude, stream gradient and the values of the HQA index that reflected more natural features in the channel and river corridor were most important. The River Habitat Survey (RHS) method reflects not only the morphology but also the relationships between habitat features and the structure of macroinvertebrate communities and it provides a more holistic approach to assessing the health condition of stream ecosystems. Headwater streams support unique macroinvertebrate taxa that are found nowhere else in a catchment and may also constitute refuges for in-stream biota. Some of the least water pollution-tolerant macroinvertebrate taxa were recorded