The role of periphytic algae in the determination of ecologically acceptable flow in running waters
- Authors: Nataša SMOLAR-ŽVANUT
- Citation: Acta hydrotechnica, vol. 19, no. 30, pp. 65-89, 2001.
- Abstract: To determine ecologically acceptable flow (EAF), it is vital to have knowledge of the periphyton community, since the algae represent the initial stage of the food chain in running waters, and respond quickly to environmental changes and act as substrata and refuges for a number of water organisms. The EAF value should assure such quantity and quality of water that substantial changes in the composition and functioning of the periphyton community do not occur. In different seasons of the years 1998-1999, during the period of low flows, the impact of abstractions on the periphyton community and on hydrological characteristics was assessed in the Sava Dolinka River in the abstraction section for the Moste power plant, and in the Soča River, in the abstraction sections for the Doblar and Ajba power plants. The role of periphytic algae in the determination of EAF in flowing waters was defined. Results of the study show qualitative and quantitative hydrological, biological, and physicochemical changes downstream of the dams. The results of the hydrological analyses show substantial changes in the hydrological regime and a predominance of gravel deposits with a considerable proportion of coarse grains downstream of the dams. Due to abstractions, the physicochemical composition of water downstream of the dams is no longer defined by conditions in the upper reaches of the river, but by tributaries downstream of the catchment area. A constant flow, as well as a rare occurrence of high waters downstream of the dams has given rise to a great diversity of periphyton and to differences in the periphyton biomass here, compared with reference sites upstream of the dams.
- Keywords: periphytic algae, ecologically acceptable flow, water abstraction
- Full text: a30-ns.pdf