The classification of European rivers comes from the fish

fauna Fauna is all of the animal life present in a particular region or time. The corresponding term for plants is ''flora'', and for fungi, it is '' funga''. Flora, fauna, funga and other forms of life are collectively referred to as '' biota''. Zoo ...

found in them. Changes in

taxonomic Taxonomy is the practice and science of categorization or classification. A taxonomy (or taxonomical classification) is a scheme of classification, especially a hierarchical classification, in which things are organized into groups or types. ...

composition relate to physical and chemical changes that occur longitudinally.

Zonation (from headwater to estuary)

Trout zone

This zone has a characteristic steep gradient, fast flowing water and cool temperature. The fast flow rate causes turbulence which keeps the water well oxygenated. Fish species found in this zone usually lay

adhesive Adhesive, also known as glue, cement, mucilage, or paste, is any non-metallic substance applied to one or both surfaces of two separate items that binds them together and resists their separation. The use of adhesives offers certain advant ...

eggs that can stick to the substrate, this is to help prevent eggs being carried down stream by the water flow. Characteristic fish species are: *

Brown trout The brown trout (''Salmo trutta'') is a European species of salmonid fish that has been widely introduced into suitable environments globally. It includes purely freshwater populations, referred to as the riverine ecotype, ''Salmo trutta'' morph ...

(''Salmo trutta'') *

Atlantic salmon The Atlantic salmon (''Salmo salar'') is a species of ray-finned fish in the family Salmonidae. It is the third largest of the Salmonidae, behind Siberian taimen and Pacific Chinook salmon, growing up to a meter in length. Atlantic salmon are ...

(''Salmo salar'') * Bullhead (''Cottus gobio'') *

Loach Loaches are fish of the superfamily Cobitoidea. They are freshwater, benthic (bottom-dwelling) fish found in rivers and creeks throughout Eurasia and northern Africa. Loaches are among the most diverse groups of fish; the 1249 known species of ...

(''Barbatula barbatula'')

Grayling zone

Similar in physical characteristics to the Trout zone, although the temperature is usually slightly higher. Fish species in this zone also lay adhesive eggs. Characteristic fish species include all of the above species, with the addition of; * Grayling (''Thymallus thymallus'') *

Minnow Minnow is the common name for a number of species of small freshwater fish, belonging to several genera of the families Cyprinidae and Leuciscidae. They are also known in Ireland as pinkeens. Smaller fish in the subfamily Leusciscidae are c ...

(''Phoxinus phoxinus'') * Chub (''Leuciscus cephalus'') *

Dace A dace is a small fish that can be one of many different species. The unmodified name is usually a reference to the common dace (''Leuciscus leuciscus''). This, like most fish called "daces", belongs to the family Cyprinidae, mostly in subfamily ...

(''Leuciscus leuciscus'')

Barbel zone

This zone is essentially lowland, but retains some characteristics of upland rivers. It has a gentle gradient with a moderate water flow and temperature. It also has a good oxygen content and a mixed substrate of silt and gravel in which plants can take root. Most of the fish species found in this zone lay their eggs in the vegetation on the river bed, this provides them with good protection and allows the eggs a good supply of oxygen given off from

photosynthesis Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored i ...

in the plants. Characteristic fish species include all of the species from the previous zones with addition of; *

Barbel Barbel may refer to: *Barbel (anatomy), a whisker-like organ near the mouth found in some fish (notably catfish, loaches and cyprinids) and turtles *Barbel (fish), a common name for certain species of fish **''Barbus barbus'', a species of cyprinid ...

(''Barbus barbus'') *

Roach Roach may refer to: Animals * Cockroach, various insect species of the order Blattodea * Common roach (''Rutilus rutilus''), a fresh and brackish water fish of the family Cyprinidae ** ''Rutilus'' or roaches, a genus of fishes * California roach ...

(''Rutilus rutilus'') *

Rudd ''Scardinius'' is a genus of ray-finned fish in the family Cyprinidae commonly called rudds. Locally, the name "rudd" without any further qualifiers is also used for individual species, particularly the common rudd (''S. erythrophthalmus''). Th ...

(''Scardinius erythrophthalmus'') *

Perch Perch is a common name for fish of the genus ''Perca'', freshwater gamefish belonging to the family Percidae. The perch, of which three species occur in different geographical areas, lend their name to a large order of vertebrates: the Percif ...

(''Perca fluviatilis'') *

Pike Pike, Pikes or The Pike may refer to: Fish * Blue pike or blue walleye, an extinct color morph of the yellow walleye ''Sander vitreus'' * Ctenoluciidae, the "pike characins", some species of which are commonly known as pikes * ''Esox'', genus of ...

(''Esox lucius'') *

Eel Eels are ray-finned fish belonging to the order Anguilliformes (), which consists of eight suborders, 19 families, 111 genera, and about 800 species. Eels undergo considerable development from the early larval stage to the eventual adult stage ...

(''Anguilla anguilla'')

Bream zone

The true lowland zone, has a very gentle gradient and slow flowing water, there is usually good oxygen content but the temperature is much more variable than in the other zones. This zone has a silty substrate and is often

turbid Turbidity is the cloudiness or haziness of a fluid caused by large numbers of individual particles that are generally invisible to the naked eye, similar to smoke in air. The measurement of turbidity is a key test of water quality. Fluids can ...

. Fish species found in this zone lay adhesive eggs in the weeds. Most upland fish species can not survive in this zone. Characteristic fish species include only a few species from the Barbel zone (Roach, Rudd, Perch and Pike), with the addition of: *

Bream Bream ( ) are species of freshwater and marine fish belonging to a variety of genera including '' Abramis'' (e.g., ''A. brama'', the common bream), '' Acanthopagrus'', ''Argyrops'', '' Blicca'', '' Brama'', '' Chilotilapia'', ''Etelis'', '' L ...

(''Abramis brama'') *

Tench The tench or doctor fish (''Tinca tinca'') is a fresh- and brackish-water fish of the order Cypriniformes found throughout Eurasia from Western Europe including the British Isles east into Asia as far as the Ob and Yenisei Rivers. It is also ...

(''Tinca tinca'') *

Carp Carp are various species of oily freshwater fish from the family Cyprinidae, a very large group of fish native to Europe and Asia. While carp is consumed in many parts of the world, they are generally considered an invasive species in parts of ...

(''Cyprinus carpio'')

References

Aarts, B. G. W. and Nienhuis, P. H. (2003) ‘Fish zonations and guilds as the basis for assessment of ecological integrity of large rivers’, Hydrobiologia, 500, pp. 157–178. doi: 10.1023/A:1024638726162. {{DEFAULTSORT:European River Zonation Rivers of Europe