River Avon

General site character

• Inland water bodies (Standing water, Running water) (95%)
  
• Bogs, Marshes, Water fringed vegetation, Fens (2%)
  
• Heath, Scrub, Maquis and Garrigue, Phygrana (2%)
  
• Broad-leaved deciduous woodland (1%)
  

Annex I habitats that are a primary reason for selection of this site

• 3260 Water courses of plain to montane levels with the Ranunculion fluitantis and Callitricho-Batrachion vegetation

  The Avon in southern England is a large, lowland river system that includes sections running through chalk and clay, with transitions between the two. Five aquatic Ranunculus species occur in the river system, but stream water-crowfoot Ranunculus penicillatus ssp. pseudofluitans and river water-crowfoot R. fluitans are the main dominants. Some winterbourne reaches, where R. peltatus is the dominant water-crowfoot species, are included in the SAC.

Annex I habitats present as a qualifying feature, but not a primary reason for selection of this site

• Not Applicable

Annex II species that are a primary reason for selection of this site

• 1016 Desmoulin's whorl snail Vertigo moulinsiana

  There is an extensive population of Desmoulin’s whorl snail Vertigo moulinsiana along about 20 km of the margins and associated wetlands of the Rivers Avon, Bourne and Wylye. This is one of two sites representing the species in the south-western part of its range, in chalk stream habitat. It occurs here in a separate catchment from the Kennet and Lambourn, within an environment more heavily dominated by arable agriculture.

• 1095 Sea lamprey Petromyzon marinus

  The Avon represents sea lamprey Petromyzon marinus in a high-quality river in the southern part of its range. There are excellent examples of the features that the species needs for survival, including extensive areas of sand and gravel in the middle to lower reaches of the river where sea lampreys are known to spawn.

• 1096 Brook lamprey Lampetra planeri

  The Avon is a high-quality river that represents the southern part of the range of brook lamprey Lampetra planeri. A healthy, stable population occurs in the main river and in a number of tributaries. The main river, and in particular its tributaries, provides clean beds of gravel for spawning and extensive areas of fine silt for juveniles to burrow into.

• 1106 Atlantic salmon Salmo salar

  The Avon in southern England represents a south coast chalk river supporting Atlantic salmon Salmo salar. The salmon populations here are typical of a high-quality chalk stream, unaffected by the introduction of genetic stock of non-native origin. The Avon has an excellent mosaic of aquatic habitats, which include extensive areas of gravels essential for spawning and growth of juvenile fry. There has been limited modification of the river course by comparison with many other southern lowland rivers in England.

• 1163 Bullhead Cottus gobio

  The Avon represents bullhead Cottus gobio in a calcareous, relatively unmodified river in the southern part of its range in England. The River Avon has a mosaic of aquatic habitats that support a diverse fish community. The bullhead is an important component of this community, particularly in the tributaries.

Annex II species present as a qualifying feature, but not a primary reason for site selection

• Not Applicable