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The aim of this study was to determine the effect of trout aquaculture effluents on the Drwęca River. The count of opportunistic pathogen Pseudomonas fluorescens (OPPF) in the total Pseudomonas fluorescens population (TPFP) were determined by plating on King B medium and fluorescence in situ hybridization. The resistance of OPPF strains to 12 antibiotics and two disinfectants was evaluated. Significant differences (p &le, 0.05) in OPPF counts were found between seven sampling sites. OPPF counts were highest in samples collected directly downstream from three fish farms. More than 50% of these isolates demonstrated multiple-drug resistance to ampicillin, mezlocillin, cefotaxime, norfloxacin, tetracycline and two disinfectants (Steridial and chloramine T). Of these, 52% were resistant to high doses of cefotaxime and norfloxacin (MIC &ge, 256 &micro, g&middot, mL&minus, 1), and 65% were resistant to the maximum doses of Steridial (MIC Ste &ge, 25 mL&middot, m&minus, 3) and chloramine T (MIC Chlor &ge, 20 mg&middot, L&minus, 1). All OPPF sampled upstream from the farms were sensitive to low concentrations of CTX (cefotaxime) and NOR (norfloxacin) (MIC &le, 2 &micro, 1), Steridial (MIC Ste &le, 5 mL&middot, 3) and chloramine T (MIC Chlor &le, 2.5 mg&middot, 1). Agglomerative clustering revealed two clusters: strains from samples collected upstream and downstream from trout farms. The results indicate that aquaculture effluents significantly affect the prevalence of biocides resistant OPPF along the river continuum.

Restoring lakes with hypolimnetic withdrawal can severely threaten water quality and biocenosis downstream. The objective of this study was to evaluate the effect of lake restoration on riverine zooplankton during a period of intense hypolimnion water inflow. Zooplankton density and biomass were determined in water samples. The water samples were also analyzed to determine the following physicochemical parameters: flow rate, dissolved oxygen, hydrogen sulphide, sulphate, ammonium nitrogen, nitrate nitrogen, total phosphorous, soluble reactive phosphorus, total organic carbon, and temperature. The results of multiple regression indicated that water flow was the most significant variable and was the best predictor of total zooplankton and rotifer density. Soluble reactive phosphorous was the main predictor of copepod biomass and density. Our study showed that hypolimnetic withdrawal disturbed the natural process of planktic community transformation, which was linked to the environmental shift from lacustrine to riverine. During the study, zooplankton density and biomass were low, but not as low as when the pipeline was operating at maximum output. At present, this lake restoration method has become more sustainable, because the adverse effects of hypolimnetic withdrawal on the recipient river have been minimized and limited to several weeks.

The effects of five towns on river water pollution were examined along the Łyna River (southern watershed of the Baltic Sea, northern Poland). The relationships among the spatially derived indicators of urbanization, environmental variables, and physico-chemical and microbiological data (heterotrophic plate count at 22 and 37 °C, and fecal coli) obtained from longitudinal river profiling have been examined with the use of multivariate analyses such as principal component analysis with factor analysis (PCA/FA) and hierarchical cluster analysis (HCA). We recognized the river channel as an environmental path that links serial urban areas into an "urban river continuum." An overall increasing trend in nutrients and indicator bacteria from suburban headwaters to urbanized sections of the river was detected despite a significant decrease in those between the towns. We concluded that the role of a multicity is equally as important as a single urban area in predicting the impacts of man-made pollutants on river water quality.

The objective of this study was to evaluate the effect of lake restoration by the hypolimnetic withdrawal method on the intensity of ambient odour in the vicinity of the pipeline outlet. The study was carried out in 2012-2013 from the beginning of the summer stagnation period in Lake Kortowskie to complete overturn in fall. Samples of river water and ambient air were collected from two sites: near the pipeline outlet (PO) and behind the academic campus (AC). A total of 44 air samples and 44 water samples were analysed. Odour intensity was measured in samples of ambient air. The following physicochemical parameters of water were determined: flow rate, dissolved oxygen (DO), hydrogen sulphide (H2S), sulphate (SO4), ammonium nitrogen (NH4-N), total nitrogen (TN), dissolved nitrogen (DN), total particulate nitrogen (T-PN), total organic carbon (TOC), dissolved organic carbon (DOC) and total particulate organic carbon (T-POC). Water samples were also analysed to determine total bacterial abundance (TBA) and the counts of bacterial rods, cocci and spiral-shaped bacteria, and sulphate-reducing bacteria (SRB). Significant variations in odour intensity were noted between years and sampling sites. Odour was significantly determined by the proportion of lake water in river water. It was also significantly correlated (P2S, NH4-N, TBA and counts of SRB, rod- and spiral-shaped bacteria only in.

The aim of the study was to determine the effects of land use management on changes in the fecal contamination of water in the Łyna River, one of the main lowland watercourses in the southern watershed of the Baltic Sea (northern Poland). A total of 120 water samples were collected in different seasons of 2011 and 2012 at 15 sites where the river intersected forest (FA), agricultural (AA), and urbanized (UA) areas. Fecal indicator bacteria (FIB), the counts of Enterobacteriaceae and Escherichia coli, total bacterial counts (TBCs), and domain Bacteria (EUB338) were determined by culture-dependent and culture-independent methods. Temperature, pH, chemical oxygen demand, dissolved oxygen, total dissolved solids, ammonia nitrogen, nitrite nitrogen, nitrate nitrogen, orthophosphate, and total phosphorus were also determined. The lowest bacterial counts were noted in water samples collected in FA, and the highest in samples collected in UA. Statistically significant differences were determined between bacterial populations across the analyzed land use types and in different sampling seasons. Significant correlations were also observed between the populations of FIB and physicochemical parameters. The results indicate that land use type influenced FIB concentrations in river water. The combined use of conventional and molecular methods improves the accuracy of fecal contamination analyses in river ecosystems.