Background. Fish-based indices for evaluation of river ecosystem quality have been used since the 1980s, when the Index of Biotic Integrity (IBI) was first introduced. Assessment of the ecological status of rivers, based on fish assemblages is required by the Water Framework Directive. During last 15 years a number of national assessment methods based on fish fauna were developed. The recently designed tool for fish-based assessment of ecological status (EFI+IBI_PL) applied in river monitoring in Poland is presented in this paper. Material and methods. The new European Fish Index EFI+ is a multimetric tool consisting of two specific indices, each with two metrics developed separately for salmonid-and cyprinid-river zones. Those metrics were used in the European intercalibration process to validate national methods. However, the original EFI+ method is not adequate to some lowland river types (physical-factor classification), so it was complemented by a typespecific modification of the Index of Biotic Integrity (IBI_PL). The method was tested on fish data from 493 sites located in 431 surface water bodies sampled in 2011-2012 according to the CEN standard 14011. Results. The EFI+ index was adapted to the specificity of Polish rivers by eliminating some inconsistences of the ecoregion division and problems related to the lack of the Dniester River in the EFI+ software and presented in this paper as EFI+PL. The index of diadromous fish occurrence (D) was also adapted from an original EFI+ method and used as a supplementary assessment tool. Specific IBI metrics were developed for large lowland rivers (with sandy or gravel bottom substrate), organic rivers (flowing through peat areas), and rivers connecting lakes (with the presence or lack of salmonid fish species). A software tool for indices calculation was also developed. The method combination (EFI+IBI_PL) was than tested on a set of 493 monitoring sites sampled in 2011-2012. Both indices classified the highest percentage of sites into moderate ecological state/potential class, but for IBI_ PL this percentage was much higher than for EFI+. Percentage of sites classified to good ecological status or high ecological potential by IBI_PL index were lower than for EFI+. The analysis indicates the consistence of classification for 77% of sites to high/good and below good ecological status by the EFI+PL/IBI_PL method and pressure index. Conclusion. The results of a two-years monitoring program show that the combination of modified EFI+ and IBI methods can be applied as a tool for river ecological status assessment in Poland, however some further method modifications are needed.
We estimate over 200,000 km or 10% of previously free-flowing river habitat length has been lost due to impoundments, an amount equivalent to the entire length of rivers in Italy. This loss strongly depends on the biogeographical location and a type of impounding barrier. European rivers are disconnected by more than one million man-made barriers that physically limit or completely block aquatic species migration and contribute to the loss of freshwater habitats8. One of the pervasive effects of barriers is the one caused by impoundment, which directly modifies lotic (flowing) stretches of river into lentic (lake-like) habitats5. Depending on structure and composition of fish communities expected at the barrier location the biological consequences may vary. EU-wide analysis of fish communities observed at river sections with low human induced alteration resulted in a macrohabitat classification of European rivers into 15 river types with expected fish community structure. This set a baseline for assessing the impacts of six main barrier types (dams, weirs, sluices, culverts, ramps, and fords) on river fish habitats across Europe. The largest habitat losses are caused by dams, weirs and sluices in mountainous areas where fish most sensitive to ponding are expected. Although many impoundments are smaller than in lowlands their individual impacts are the greatest. Hence, regional variation in the magnitude of impoundment impact is not only a function of barrier height and density, but to large extent of biogeographical location and barrier type. Strategies for enhancing European riverine biodiversity should focus on prioritization of most sensitive regions and barrier types causing high degree of habitat fragmentation. This work is based on four novel methodological approaches: fish community grouping into habitat use guilds, continental river reference model for ecological sound river management, landscape scale application of physical habitat models and conceptual model of impoundment impacts on fish habitat.
A bstract: The ichthyofauna of the Warsaw section of the Vistula River as well as selected water bodies in Warsaw was described. The information was collected from catches, analysis of stocking registers as well as interviews with anglers carried out between 1989 and 2002. The existence o f 40 fish species was noted, including 33 species in the Vistula River. 3 to 11 species, belonging to eurytopic and stagnophilic ecological guilds, was registered in particular water bodies. The results indicate that diversified fish assemblages exist in Warsaw water bodies that are subject to high anthropogenic pressure, including rich fish assemblages in the Vistula River.
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