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EN
The study was performed in five fourth-order tributaries of the Bystrzyca Lubelska River (Eastern Poland, Lublin Upland), differing in the degree of river-bed transformation and level of pollution. Hydro-morphological methods (descriptive method by Ilnicki and Lewandowski - IL, and index method by Oglecki and Pawlat - OP) and biological indices based on the composition of zoobenthos (Diversity - D, and index based on proportions between the density of Oligochaeta and Chironomidae - O/Ch) permitted distinguishing of four classes, from II to V. The distinguishing of only two quality classes (III and IV) was possible by means of physical-chemical methods and by benthic index BMWP_PL. Those two methods seem to show the lowest sensitivity to the spatial variability of the environment quality. The BMWP_PL index was the least sensitive to year-to-year environmental changes, and O/Ch was the most sensitive. Relatively high conformity was obtained between hydro-morphological assessments performed by means of the OP and IL methods. Results obtained by means of these tools weakly corresponded with the physical-chemical assessments. The latter assessments were the most similar to those obtained by means of the BMWP_PL (degree of similarity = 57%) and D (47%) indices, and considerably less in the case of O/Ch (36%). The BMWP_PL and D indices better corresponded with the results of the hydro-morphological assessment performed by means of the IL method than with those performed by means of the OP method while D index showed a reverse pattern. The O/CH index proved useful for the assessment of the degree of organic pollution of the river’s water, but not the sediments.
EN
The influence of submerged macrophytes on composition, abundance and distribution of epiphytic and benthic chironomids was investigated in five lakes differing in the development of vegetation cover. Studied lakes represented three types, classified according to the concept of Alternative Stable States as: macrophyte dominated MD (dense vegetation), phytoplankton-macrophyte dominated PMD (sparse, patchy vegetation) and phytoplankton dominated PD (lack of submerged vegetation). Both zoocenosis responded differently to the changes in macrophyte cover. The density and biomass of benthic midges (density and biomass per m[^2] of bottom surface) were visibly higher in the patchy vegetated lakes; the abundance of epiphytic chironomids did not show any regularity. The species composition of epiphytic chironomids differed visibly between particular lake types, changed with the decrease of macrophyte cover. The composition of benthic midges was similar in all lake types. The studies showed at strong dependence of the proportion of epiphytic to benthic chironomids on the cover of macrophytes. In MD lakes the phytophilous midges were more abundant than benthic; in PMD lakes we observed the opposite pattern.
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