Paweł Oglęcki

Hydromorphological complexity as a driver of the diversity of benthic invertebrate communities in the Czarny Dunajec River, Polish Carpathians

To verify whether the variability in benthic invertebrate communities along the mountainous Czarny Dunajec River is mainly driven by the variation in hydromorphological or water quality, diversity of the communities was determined for 18 cross-sections with 1–5 low-flow channels and compared with the complexity of physical habitat conditions and with physico-chemical water quality. An increase in the complexity of flow pattern in the river was associated with increasing cross-sectional variability in physical habitat parameters. Distinct hydromorphological characteristics of the cross-sections with a given number of low-flow channels were especially pronounced if the analysis was limited to the parameters measured directly, whereas calculated complex hydraulic and sedimentary variables represented information overload. Taxonomic richness of the invertebrate communities was unrelated to physico-chemical water parameters, which consistently pointed to the high water quality. Instead, the richness positively correlated with a degree of variation in physical habitat parameters and was best predicted by the number of low-flow channels in a river cross-section. This study indicates that physical habitat complexity in a mountain river can be considered a proxy to the diversity of its invertebrate communities and that restoration of such complexity will be necessary for future recovery of invertebrate communities in impacted river sections.

Interpretation of the invertebrate-based BMWP-PL index in a gravel-bed river: insight from the Polish Carpathians

Like its British prototype (Biological Monitoring Working Party score system), the Polish benthic invertebrate-based BMWP-PL index is commonly regarded as an indicator of river water quality. This interpretation of the index has been verified in a study of the gravel-bed Biała River. Benthic macroinvertebrates were sampled at 10 sites and compared in one channelized and one unmanaged cross-section per site. The resulting taxa richness and BMWP-PL index scores were compared with water quality and physical habitat characteristics in the cross-sections. Channelized and unmanaged cross-sections clearly differed in their physical habitat conditions, and water quality characteristics mostly varied in the downstream direction. Particular cross-sections hosted between 3 and 26 invertebrate taxa, with the respective BMWP-PL scores indicating the water in the surveyed cross-sections varied between high and poor quality. However, the BMWP-PL scores were unrelated to physicochemical characteristics of the river water, which consistently pointed to high water quality. Instead, the scores were significantly related to several physical habitat variables, with the number of low-flow channels in a cross-section explaining the largest proportion of the variance in the index values. The relationship of the scores with the complexity of flow pattern in the river and a lack of their dependence on physicochemical water characteristics show that the BMWP-PL index should not be regarded as an indicator of water quality but rather as an indicator of the ecological status of rivers, dependent both on their hydromorphological and water-quality characteristics.

Assessment of river hydromorphological quality for restoration purposes: an example of the application of RHQ method to a Polish Carpathian river

Planning and implementation of effective restoration projects require appropriate assessment of a river’s hydromorphological status. Two European standards on hydromorphological assessment of rivers and hydromorphological assessment methods used in Poland are reviewed in the context of their applicability for river restoration purposes. River Hydromorphological Quality assessment method is presented with a case study of the Biała River, Polish Carpathians, where this assessment was used as basis for a restoration project aimed to establish an erodible river corridor. The results of the assessment revealed significant differences in hydromorphological quality between unmanaged and channelized river cross-sections, indicating channel regulation as a major cause of the hydromorphological degradation of the Biała and confirming the choice of the erodible river corridor as an appropriate method of its restoration. The assessment indicated hydromorphological features of the river that were severely modified within the channelized reaches and which are likely to improve the most with the removal of bank protection and allowing free channel migration.

Ecological state of a mountain river before and after a large flood: Implications for river status assessment

Assessment of the ecological status of rivers is key to monitoring the achievement of the environmental goal of the EU Water Framework Directive and the success of restoration projects. In summer of 2009 and 2010, repeated assessments of physical habitat conditions and of fish and benthic invertebrate communities were performed at low-flow conditions in 10 unmanaged and 10 channelized cross-sections of the Biała River, Polish Carpathians. Between the two surveys, an 80-year flood occurred, significantly affecting habitat characteristics and river communities. In unmanaged cross-sections, active channel width increased, whereas the degree of cross-sectional variation of flow velocity decreased. In channelized cross-sections, the increase in active channel width and the cross-sectional variation of flow velocity was accompanied by a decrease in bed-material grain size. Before the flood, the unmanaged cross-sections hosted 2.3 times more benthic invertebrate taxa than the channelized ones, whereas after the flood, the number of taxa they supported was so reduced that the taxonomic richness of benthic invertebrate assemblages in both cross-section types became similar. In comparison to pre-flood conditions, the abundance of fish juveniles (YOY) in unmanaged cross-sections was reduced nearly by half; before the flood they hosted 5 times more juvenile individuals than channelized cross-sections and only twice as many after the flood. Finally, a differing assessment of flood impact on the ecological river quality was obtained with the invertebrate-based BMWP-PL index and the European Fish Index, with the former indicating a significant reduction of the quality in unmanaged cross-sections and the latter pointing to no such change. The results indicate that assessments performed before or after a major flood may yield significantly different results for the quality of abiotic and biotic elements of the river ecosystem. Final assessment should thus be based on repeated surveys to balance the effect of extreme hydrological events.

The macroinvertebrate fauna of the Młynne stream (Polish Carpathians) in the aspect of the bed load transport and water quality

Abstract The macroinvertebrate fauna of the Młynne stream (Polish Carpathians) in the aspect of the bed load transport and water quality. The qualitative composition of the bottom sediments and the bed load and suspended load transport along the mountain stream were presented. The studies were carried on the Młynne stream in Gorce (Polish Carpathians). The streams flows partially in the natural river-bed and partially in the regulated with rapids. The stream bed load is accumulated in the reservoir up to the check dam and is qualitatively different from the load deposited at the bars. The taxonomic richness of the Młynne stream is a little bigger compared with the other investigated mountain and sub-mountain streams, but lesser compared with bigger rivers. The number of taxa on the natural reaches is more than double than on the regulated ones, with more taxa of high environmental demands and high values of the BMWP-PL index. The paper brings up the question of the environmental friendly technical solutions in different human activities in the sub-mountain and mountain river valleys, advantageous for humans and the river biological diversity (or resistance for negative environmental factors) as well. Streszczenie Fauna makrobezkregowa na tle transportu rumowiska dennego oraz jakości wody w potoku Młynne w Karpatach Polskich. W artykule poruszono temat składu osadów dennych oraz transportu zawiesiny w potoku górskim. Badania przeprowadzono na potoku Młynne w Gorcach. Płynie on częściowo korytem naturalnym, a częściowo uregulowanym poprzez kaskady. Zawiesina denna jest akumulowana w zbiorniku powyżej zapory i pod względem jakościowym różni się od tej gromadzącej się na kaskadach. Fauna bezkręgowa jest dobrym wskaźnikiem zmian hydromorfologicznych i ich wpływu na ekosystem. Bogactwa gatunkowe potoku Młynne jest nieco większe niż innych badanych cieków górskich i podgórskich, ale mniejsze w porównaniu z większymi rzekami. Liczba taksonów na odcinkach naturalnych jest ponaddwukrotnie większa niż na uregulowanych, przy większym udziale gatunków bardzo dużych wymaganiach siedliskowych i dużych wartościach wskaźnika BMWP-PL. W pracy poruszono problem przyjaznych środowisku rozwiązań technicznych przy różnych rodzajach działalności ludzkiej w dolinach rzek górskich i podgórskich, mogących korzystnie wpływać zarówno na dobro człowieka, jak różnorodność biologiczną i odporność ekosystemu na niekorzystne czynniki zewnętrzne.