| |
Definition of tidal flats (sand and mud flats)
Mud flats (and sand flats) are sedimentary inter tidal habitats created by
deposition in low energy coastal environments, particularly estuaries and other
sheltered areas. The sediment which make them up consists mostly of silts and
clays with a high organic content. Towards the mouths of estuaries, where salinity
and wave energy are higher the proportion of sand increases. Mudflats are intimately
linked by physical processes and may be dependent on other coastal habitats
such as soft cliffs (to help provide sediment). They commonly appear in the
natural sequence of habitats between sub-tidal channels and vegetated saltmarshes.
In large estuaries they can be several kilometres wide and commonly form the
largest part of the inter tidal area of estuaries. Of the estimated 531,000ha
of tidal 'estuarine' wetland habitat in Great Britain some 267,800ha are tidal
sand and mud flats (Davidson & Buck 1997).
They support a number of highly specialised plant
communities. They also form an integral part of the Habitats Directive
Annex I habitats:
- 1130 - "Estuaries";
- 1160 - "Large shallow inlets and bays";
- 1150 - "Saline
lagoons" which are covered in this guide.
|
Guidance on further information: A detailed description
of "Intertidal sand and mudflats and subtidal mobile sands - An overview
of dynamics and sensitivity characteristics for conservation management
of marine SACs" has been produced as part of the UK marine SAC project
(Elliott et al. 1998). It can be downloaded
in pdf format @ http://www.ukmarinesac.org.uk/,
under project publications.
|
References
Davidson, N.C. & Buck, A.L.
1997.
An Inventory of UK Estuaries: Introduction and Methodology.
An Inventory of UK Estuaries
Joint Nature Conservation Committee.
Elliott, M., Nedwell, S., Jones, N.V., Read, S.J., Cutts, N.D. & Hemingway, K.L.
1998.
Intertidal Sand and Mudflats and Subtidal Mobile Sandbanks (Volume II): an Overview of Dynamic and Sensitivity Characteristics for Conservation Management of Marine SACs. .
Scottish Association for Marine Science (UK Marine SACs Project)
UK Marine SACs Project.
|
|
