other Biology & physiology Biology & physiology پژوهشي Orginal research papers Variation of hydrochemical conditions, with special reference to adequacy of waters as fish habitats, was traced based on selected hydrochemical parameters obtained during the studies conducted from February 2013 till February 2014 year. The results were compared with earlier studies. The sources of organic pollution were identified, and the effect of biogenic substances on the biomass, as well as the self-purification capability of the river, were assessed. The total suspension exceeded the requirements for waters which are habitats of both salmonid and cyprinid fishes. Compared to the previous years, the load of organic and inorganic matter in the waters of Wiśniówka River increased; this may have resulted from external inflow, neighbourhood of the hatchery but also, to a small extent, from internal supply. The high availability of nitrogen-(N-NH₄⁺; N-NO₂^-, N-NO₃^-) and phosphorus-(total phosphorus; P-PO₄^3-) based biogenic (substances favoured the biomass production, thus contributing to the increase in organic matter load in the river. Aquatic, Environment, Estuary, Fish, Pollution 690 712 http://jifro.ir/browse.php?a_code=A-10-1891-2&slc_lang=other&sid=1 M. Socha msocha@zut.edu.pl 100319475328460029608 100319475328460029608 Yes Department of Water Sozology, West Pomeranian University of Technology in Szczecin, K. Królewicza Street 4, 71-550 Szczecin, Poland. Department of Water Sozology, West Pomeranian University of Technology in Szczecin, K. Królewicza Street 4, 71-550 Szczecin, Poland. M. Bonisławska 100319475328460029609 100319475328460029609 No Department of Water Sozology, West Pomeranian University of Technology in Szczecin, K. Królewicza Street 4, 71-550 Szczecin, Poland. Department of Water Sozology, West Pomeranian University of Technology in Szczecin, K. Królewicza Street 4, 71-550 Szczecin, Poland. A. Tórz 100319475328460029610 100319475328460029610 No Department of Water Sozology, West Pomeranian University of Technology in Szczecin, K. Królewicza Street 4, 71-550 Szczecin, Poland. Department of Water Sozology, West Pomeranian University of Technology in Szczecin, K. Królewicza Street 4, 71-550 Szczecin, Poland. A. Rybczyk 100319475328460029611 100319475328460029611 No Department of Water Sozology, West Pomeranian University of Technology in Szczecin, K. Królewicza Street 4, 71-550 Szczecin, Poland. Department of Water Sozology, West Pomeranian University of Technology in Szczecin, K. Królewicza Street 4, 71-550 Szczecin, Poland. A. Nędzarek 100319475328460029612 100319475328460029612 No Department of Water Sozology, West Pomeranian University of Technology in Szczecin, K. Królewicza Street 4, 71-550 Szczecin, Poland. Department of Water Sozology, West Pomeranian University of Technology in Szczecin, K. Królewicza Street 4, 71-550 Szczecin, Poland. A. Tański 100319475328460029613 100319475328460029613 No Department of Hydrobiology, Ichthyology and Biotechnology of Reproduction, West Pomeranian University of Technology in Szczecin, K. Królewicza Street 4, 71-550 Szczecin, Poland. Department of Hydrobiology, Ichthyology and Biotechnology of Reproduction, West Pomeranian University of Technology in Szczecin, K. Królewicza Street 4, 71-550 Szczecin, Poland. R. Pender 100319475328460029614 100319475328460029614 No Polish Angling Association Szczecin Polish Angling Association Szczecin