Ecological indicators of water quality in small rivers

At the present time hydrobiological indicators are widely used for the control of surface water quality. Results of the applying of methods suggested at the 1st Soviet-American seminar (1975), development of improved methods and estimation of their usefulness for various conditions are presented in this report. Among the criteria permitting an estimation of the degree and character of changes in water quality and their connection with the functioning of river ecosystems in general, the biological tests of natural waters appears to be the most universal one and is being carried out in two main directions — ecological and physiological. This study summarises approaches in both directions

Effects of some polycyclic aromatic hydrocarbons on the natural population of marine bacterioplankton

Doubling rate, production and the daily P/B ratios of natural bacterioplankton populations of the Gulf of Riga were estimated under the impact of 0.001 mg/dm3 anthracene and phenanthrene. In many cases, reduction in the total number of microorganisms was observed, coupled with a decrease in bacterial production. Studies on 24 h exposure to anthracene and phenanthrene demonstrated toxicity of the hydrocarbon concentrations used to the microbial communities of the Gulf of Riga

Discharge areas — A comparison between three regions in the southern Baltic

AbstractTideless estuaries are very common on the western, southern and eastern Baltic coast. They play an important role as buffers and filters for the Baltic Proper. These functions can vary, depending on discharge areas and the situation in the estuaries themselves. Our knowledge of the estuaries varies widely, ranging from more or less simple descriptions to a fairly complete understanding of the processes taking place in their ecosystems. So far, only one preliminary comprehensive study has been performed for the whole area (Baltic Sea Environment Proceedings No. 40, HELCOM 1991).Three different discharge areas connected to tideless estuaries are compared in some detail:-the shallow polytrophic Darss-Zingst Bodden Chain, Germany-the shallow eutrophic Puck Bay, Poland-the deeper mesotrophic Gulf of Riga, Latvia.Starting points are discharge areas, discriptions of the water bodies and main loads. The development of the ecosystems under the influence of anthropogenic impacts during the last 40 years is then described.Conclusions are drawn concerning:-the general behaviour of such systems-the benefits and drawbacks of the discharge areas, the loads, and the structures and functions of the estuaries-special problems regarding the buffer and filtering capacities of the systems in question-economic consequences.High variability and elasticity are the main characteristics of these tideless estuarine ecosystems. Multivalente economic utilization of these resources and functions is the best way to save such ecosystems and money as well

Ecological indicators of water quality in small rivers

At the present time hydrobiological indicators are widely used for the control of surface water quality. Results of the applying of methods suggested at the 1st Soviet-American seminar (1975), development of improved methods and estimation of their usefulness for various conditions are presented in this report. Among the criteria permitting an estimation of the degree and character of changes in water quality and their connection with the functioning of river ecosystems in general, the biological tests of natural waters appears to be the most universal one and is being carried out in two main directions — ecological and physiological. This study summarises approaches in both directions