European river zonation

European river zonation

The classification of European rivers comes from the fish fauna found in them. Changes in taxonomic 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 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 ("Salmo trutta")
* Atlantic salmon ("Salmo salar")
* Bullhead ("Cottus gobio")
* Stone loach ("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 ("Phoxinus phoxinus")
* Chub ("Leuciscus cephalus")
* Dace ("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 in the plants.

Characteristic fish species include all of the species from the previous zones with addition of;

* Barbel ("Barbus barbus")
* Roach ("Rutilus rutilus")
* Rudd ("Scardinius erythrophthalmus")
* European perch ("Perca fluviatilis")
* Pike ("Esox lucius")
* Eel ("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. 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 Barble zone (Roach, Rudd, Perch and Pike), with the addition of:

* Bream ("Abramis brama")
* Tench ("Tinca tinca")
* Carp ("Cyprinis carpio")


Wikimedia Foundation. 2010.

Игры ⚽ Поможем написать курсовую

Look at other dictionaries:

  • List of rivers of Europe — These are the main rivers of Europe (ecologically, the extreme west of the Palearctic ecozone which includes Russia in the east). See each article for their tributaries, drainage areas, etc.The longest rivers of Europe are: *Volga (3,692 km/2,294 …   Wikipedia

  • List of rivers of Portugal — This is a list of the rivers of Portugal. There are only rivers in Continental Portugal, and none in the islands of Madeira and the Azores.List*Águeda River *Alcoa River *Antuã *Arade *Caia River *Côa River *Douro *Guadiana *Limia River *Minho… …   Wikipedia

  • North America — North American. the northern continent of the Western Hemisphere, extending from Central America to the Arctic Ocean. Highest point, Mt. McKinley, 20,300 ft. (6187 m); lowest, Death Valley, 276 ft. (84 m) below sea level. 400,000,000 including… …   Universalium

  • Western Africa — ▪ region, Africa Introduction       region lying south of the Sahara and east and north of the Atlantic Ocean. It is latitudinally divided into two parallel belts of land: the western portion of the Sudan, a geographic area that stretches across… …   Universalium

  • Silurian Period — Interval of geologic time, 443–417 million years ago. The third period of the Paleozoic Era, the Silurian follows the Ordovician Period and precedes the Devonian. It marks the first appearance of land plants and jawed fishes. The continents were… …   Universalium

  • boundary ecosystem — ▪ biology Introduction       complex of living organisms in areas where one body of water meets another, e.g., estuaries and lagoons, or where a body of water meets the land, e.g., marshes. The latter are often called wetlands.       Boundary… …   Universalium

  • List of life zones by region — Main article: Altitudinal zonation The climate and ecology of different locations on the globe naturally separate into life zones, depending on elevation, location, and latitude. The generally strong dependency on elevation is known as… …   Wikipedia

  • Cambrian Period — Oldest time division of the Paleozoic Era. During the Cambrian, 543–490 million years ago, there were widespread seas and several scattered landmasses. The largest continent was Gondwana. The average climate was probably warmer than today, with… …   Universalium

  • List of Cumacea literature — Extensive literature list on Cumaceans. Contents: Top · 0–9 · A B C D E F G H I J K L M N O P Q R S T U V W X Y Z A …   Wikipedia

  • Devonian Period — Interval of geologic time from 417 to 354 million years ago; it was the fourth period of the Paleozoic Era. During the Devonian, a giant continent was situated in the Southern Hemisphere (see Gondwana), and other landmasses were located in the… …   Universalium

Share the article and excerpts

Direct link
… Do a right-click on the link above
and select “Copy Link”