The occurrence and activity of sulphate-reducing bacteria in the bottom sediments of the Gulf of Gdańsk

The paper presents the results of investigations concerning the number, distribution and physiological activity of sulphate-reducing bacteria (SRB) inhabiting the bottom sediments of the Gulf of Gdańsk. The numbers of this group of bacteria range between 0.76× 103 and 1.27× 104 cells per g wet sediment. The bacterial sulphate reduction rate in bottom sediments of this area of the Baltic Sea varies from 1.89 to 31.6 nM SO2− 4 g −1 24 h−1. The numbers of SRB and their physiological activity were subject to considerable seasonal fluctuations, maximum values being noted in summer (June) and minima in spring (April). A direct relationship has been found between the number of SRB and hydrogen sulphide concentrations; there is, however, no such relationship with reference to sulphate concentrations. The numbers and distributions of SRB demonstrated considerable variation in a depth profile of bottom sediments. SRB inhabiting the bottom sediments of the Gulf of Gdańsk were able to use three different organic substrates (lactate, acetate, propionate) as electron donors and as carbon and energy sources. 106 Z. J. Mudryk, B. Podgórska, A. Ameryk, J. Bolałek