M. Socha - Department of Water Sozology, West Pomeranian University of Technology in Szczecin, K. Królewicza Street ۴, ۷۱-۵۵۰ Szczecin, Poland.
M. Bonisławska - Department of Water Sozology, West Pomeranian University of Technology in Szczecin, K. Królewicza Street ۴, ۷۱-۵۵۰ Szczecin, Poland.
A. Tórz - Department of Water Sozology, West Pomeranian University of Technology in Szczecin, K. Królewicza Street ۴, ۷۱-۵۵۰ Szczecin, Poland.
A. Rybczyk - Department of Water Sozology, West Pomeranian University of Technology in Szczecin, K. Królewicza Street ۴, ۷۱-۵۵۰ Szczecin, Poland.
A. Nędzarek - Department of Water Sozology, West Pomeranian University of Technology in Szczecin, K. Królewicza Street ۴, ۷۱-۵۵۰ Szczecin, Poland.
A. Tański - Department of Hydrobiology, Ichthyology and Biotechnology of Reproduction, West Pomeranian University of Technology in Szczecin, K. Królewicza Street ۴, ۷۱-۵۵۰ Szczecin, Poland.
R. Pender - Polish Angling Association Szczecin

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 ۲۰۱۳ till February ۲۰۱۴ 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-NH۴+; N-NO۲-, N-NO۳-) and phosphorus-(total phosphorus; P-PO۴۳-) based biogenic (substances favoured the biomass production, thus contributing to the increase in organic matter load in the river.

Aquatic, Environment, Estuary, Fish, Pollution