Species

Species used to characterize the functional ecological status of French streams: trout (brown trout) for salmonid habitats (usually cold mountain freshwaters or close to reliefs), pike for cyprinid habitats (slow lowland streams), and the grayling or white water cyprinids (barbel, dace, etc) for intermediate environments. These species are demanding and found in all natural environments with good status.

Legal classification of a watercourse based on the dominant species and worthy of protection. In principle, the river is classified in the first category when the dominant group consists of salmonids (salmon, trout) and in the second category, when the dominant group is composed of cyprinids (carp, barbel, roach, etc.). This classification determines the fishing practices.

Describes a species having part of its biological cycle at sea and another part in a river

As opposed to "benthic", it describes organisms and processes occurring in the ocean (open water) and not close to the bottom.

Sediment-dwelling worm used to determine sediment quality or even the environmental contamination of the medium by micro-pollutants.

Microscopic organism (mainly bacteria and fungi) which is involved in the decomposition and biodegradation process.

Water status characterized by a degree of presence of microorganisms (viruses, bacteria, protozoa, etc) capable of causing a more or less great health risk.

Fish that move periodically between their spawning and feeding grounds (home to the juveniles and adults). Some species live alternately in freshwater and seawater (diadromous fish), they are called "highly migratory species".