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Tidal flats - summary of values
Tidal flats whether they are accreting (State
1) or not are important in contributing to the productivity of estuaries.
They also form part of the structure which supports the food web within the
tidal embayment and hence play a critical role in both fisheries and wildlife
conservation. The high productivity associated with the tidal waters and flats
also helps to support a number of spawning and juvenile stages of some commercial
fish species. Flounders and young place are especially adapted to feed on the
animals living at or near the surface of the tidal flats. Tidal creeks are used
for oyster and other shellfish cultivation.
Tidal flats are considered especially important in providing feeding areas
for a variety of waterfowl.
Many of these, especially migratory waders, depend on the availability of suitable
invertebrate
prey which live in or on the surface of the sand or mud flat. They
also support vegetation including algae and Zostera
spp. which provide food for a smaller number of herbivores including
notably, grazing ducks and geese. The importance of the habitat for waterfowl
is reflected in the number of sites identified as being nationally and internationally
significant for this group of species (as Ramsar
sites and/or Special
Protection Areas).
Together with other tidal habitats, notably saltmarsh,
within coastal embayments they also serve a sea
defence function. Studies in the Wash suggest that they make a significant
contribution to wave
attenuation. They are also traditionally areas where waterfowl are
shot. They can be significant features in the landscape.
These values are compromised where the tidal flats are eroding (State
2). This may be of special significance in areas where a 'coastal
squeeze' is taking place.
Comment: A detailed review of the conservation value of coastal wetlands
(including tidal sand and mudflats) is provided in the "Estuaries Review"
produced by the NCC in 1991 (Davidson et al. 1991).
References
Davidson, N.C., Laffoley, D..d'A., Doody, J.P., Way, L.S. & Gordon, J.
1991.
Nature Conservation and Estuaries in Great Britain.
Nature Conservancy Council.
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