REDOX STATUS OF THE WEST POMERANIAN RIVERS AND STREAMS SELECTED FOR SETTLEMENT WITH SALMON (SALMO SALAR L.) AND SEA TROUT FRY (SALMO TRUTTA MORPHA TRUTTA L.) - RESULTS OF RESEARCH IN WINTER

Abstract

The usefulness of the measures expressing redox status of water (redox potential Eh, indicators pE = - lg [eˉ ] and rH = - lg p_H2 ) was examined for the evaluation of the quality of water in selected rivers and streams of West Pomerania (Otoczka, Molstowa, Gardominka and Rekowa). The evaluation was done under conditions which may turn out to be difficult for the survival of the salmonide fry (salmon and sea trout), that is – in the winter, after the appearance of ice cover, when the oxygen saturation of waters declines (to 61–74%). It was found out that the changes in the redox indices values (Eh = 448–468 mV) signal worsening of environmental conditions, related not only to the decline in oxygen saturation, but also with the dissolution from sediments substances which may be harmful for the salmonide fry (dissolved organic matter, ammonium compounds, manganese and iron).

Key words: water chemistry, riverine and stream water, West Pomerania, redox indices, salmonide, reintroduction