Assessment of the ecological river quality
To assess the quality of rivers, it is necessary to carry out a biological, chemical and habitat structure analysis.
1. The river structure (hydromorphological) assessment looks at the nature of the riverbed, banks and floodplain. The quantity of riffles, pools, rocks and stones, gravel and sand is as significant as the amount of dead wood in the water and the shoreline and bank fixation of a river.
Typical bottom sediments of a lower mountain stream: stones, gravel, sand and macrophytes
2. The physico-chemical assessment focusses on parameters like oxygen concentration and saturation, acidity (pH-value) and other pollutants like nutrients in the water.
Preparation of the measuring equipment for pH-value, oxygen, water temperature and conductivity.
Measuring of water quality by means of electronic measuring instruments
3. For the biological assessment, the existence of animals and plants is monitored in standardized ways. For example, experts first check whether there are any microhabitats like stones, sand, mud, dead wood and many others in the stream section to be assessed, and then they sample at these habitats all relevant groups of the aquatic biocoenosis (i.e. fish, macroinvertebrates like insects, snails, mussels, crustaceans etc., and algae as well as larger water plants).
Macroinvertebrates (insects and other groups) in a sampling instrument
A remarkable find in a near-natural mountain stream: young stone crayfish (Austrapotamobius torrentium), a rare species in Europe
Info slide about standard sampling methods