Dee Estuary/ Aber Dyfrdwy

General site character

• Tidal rivers, Estuaries, Mud flats, Sand flats, Lagoons (including saltwork basins) (81.8%)
  
• Salt marshes, Salt pastures, Salt steppes (16.1%)
  
• Coastal sand dunes, Sand beaches, Machair (0.7%)
  
• Shingle, Sea cliffs, Islets (0.5%)
  
• Bogs, Marshes, Water fringed vegetation, Fens (0.4%)
  
• Humid grassland, Mesophile grassland (0.2%)
  
• Improved grassland (0.1%)
  
• Broad-leaved deciduous woodland (0.1%)
  
• Other land (including Towns, Villages, Roads, Waste places, Mines, Industrial sites) (0.1%)
  

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

• 1140 Mudflats and sandflats not covered by seawater at low tide

  Species occurrence description not yet available.

• 1310 Salicornia and other annuals colonizing mud and sand

  The Dee Estuary is representative of pioneer glasswort Salicornia spp. saltmarsh in the north-west of the UK. Salicornia spp. saltmarsh forms extensive stands in the Dee, especially on the more sandy muds where there is reduced tidal scour. It mainly occurs on the seaward fringes as a pioneer community, and moving landwards usually forms a transition to common saltmarsh-grass Puccinellia maritima saltmarsh (SM10). There is also a low frequency of Salicornia spp. extending well inland. Associated species often include annual sea-blite Suaeda maritima and hybrid scurvy grass Cochlearia x hollandica.

• 1330 Atlantic salt meadows (Glauco-Puccinellietalia maritimae)

  The Dee Estuary is representative of H1330 Atlantic salt meadows in the north-west of the UK. It forms the most extensive type of saltmarsh in the Dee, and since the 1980s it has probably displaced very large quantities of the non-native common cord-grass Spartina anglica. The high accretion rates found in the estuary are likely to favour further development of this type of vegetation. The saltmarsh is regularly inundated by the sea; characteristic salt-tolerant perennial flowering plant species include common saltmarsh-grass Puccinellia maritima, sea aster Aster tripolium, and sea arrowgrass Triglochin maritima. In a few areas there are unusual transitions to wet woodland habitats.

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

• 1130 Estuaries
• 1210 Annual vegetation of drift lines
• 1230 Vegetated sea cliffs of the Atlantic and Baltic Coasts
• 2110 Embryonic shifting dunes
• 2120 "Shifting dunes along the shoreline with Ammophila arenaria (""white dunes"")"
• 2130 "Fixed coastal dunes with herbaceous vegetation (""grey dunes"")"  * Priority feature
• 2190 Humid dune slacks

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

• Not Applicable

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

• 1095 Sea lamprey Petromyzon marinus
• 1099 River lamprey Lampetra fluviatilis
• 1395 Petalwort Petalophyllum ralfsii