| Tayside Biodiversity - Tayside
Biodiversity Action Plan - Coastal - Estuaries |
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DEFINITION
An estuary is a partially enclosed area at least partly composed of soft tidal
shores, open to saline water from the sea and receiving freshwater from rivers,
land run-off or seepage. An estuary may broadly be divided into three
zones: the constantly submerged, the inter-tidal, and the sea-washed. These core
areas are associated with a number of significant related habitats such as sub-tidal
sandbanks, inter-tidal mud and sand, eel- or seagrass (Zostera) beds, shingle,
saltmarsh, reedswamps and coastal grazing-marsh.
KEY SITES
Tay - 12,265 hectares (LNR, SSSI, SPA, pSAC, Ramsar); south shore to be included
in the Fife Biodiversity Action Plan
Montrose Basin - 842 ha. (LNR, SSSI, SPA, Ramsar)
North Esk Kinnaber (SSSI)
Lunan Water
Elliot Water
Pitairlie Burn
Buddon Burn |
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CURRENT
STATUS AND EXTENT OF HABITAT
About 50% of the UK coastline (9,849 km) is estuarine and of this 2.5% is in
Tayside. There are two major estuaries in Tayside - the Inner Tay (12,265 ha.,
of which 5,720 ha. are inter-tidal) and Montrose Basin (842 ha., of which 739
ha. are inter-tidal). These make up most of the region’s estuarine habitat,
the remainder being accounted for by five much smaller river mouths – Pitairlie,
Buddon, Lunan, Elliot and North Esk - all of which are in Angus.
The Firth of Tay is one of the largest estuaries in Scotland and has the highest
freshwater inflow of any estuary in Britain. It can be divided into the strongly
marine outer firth (seaward of Broughty Ferry), a middle zone between Broughty
Ferry Castle and the rail bridge which exhibits the greatest variation in salinity,
and the upper estuarine reaches upstream of the bridge. The influence of spring
tides penetrates 50 km inland to about 4 km beyond Perth, but saline conditions
occur only as far upstream as Newburgh.
For the purposes of this Habitat Action Plan the upper limit of the estuary is
defined by the confluence of the Earn with the Tay – about 8 km downstream
of Perth. The lower limit is less easy to define but because estuarine conditions
are vital to otherwise coastal species such as Common seal Phoca vitulina, Sparling
Osmerus eperlanus, and Eider Somateria mollissima, their ranges within the estuary
have been taken into consideration. Consequently, the area between Buddon Ness
and Tentsmuir Point Nature Reserve (Fife) is covered by this Action Plan.
Montrose Basin, at the mouth of the River South Esk, is one of the finest examples
of an enclosed estuarine basin in the UK. It is shallow and drains almost completely
at low water, exposing a large area of mud and sand flats. 88% of the basin is
inter-tidal.
There are extensive estuarine reedbeds in the Tay (over 240 ha.) and smaller
areas elsewhere. This specific habitat will be covered by a Reedbed Action Plan.
The majority of Tayside’s saltmarshes occur at Montrose Basin. The north
shore of the Tay estuary holds 47 ha. A further 16 ha. occur at the smaller river
mouths along the Angus coast. Compared to the national UK figure of 44,400 ha.,
the total area of saltmarsh in Tayside is clearly very small, but its ungrazed
nature at Montrose is relatively uncommon.
There is also a small area of perched saltmarsh in Angus, splashed by the sea
on the cliffs within Rickle Craig Scurdie Ness SSSI, near Montrose. This is discussed
in the Maritime Cliff and Slope Action Plan.
KEY SPECIES
P = UK Priority species C = UK species of conservation concern
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| Mammals |
Otter |
Lutra lutra |
P |
| Common seal |
Phoca vitulina |
C |
| Birds |
Shelduck |
Tadorna tadorna |
C |
| Red-breasted merganser |
Mergus serator |
C |
| Goosander |
Mergus merganser |
C |
| Pink-footed goose |
Ancer brachyrhynchus |
C |
| Redshank |
Tringa totanus |
C |
| Bar-tailed godwit |
Limosa lapponica |
C |
| Eider |
Somateria mollissima |
C |
| Mute swan |
Cygnus olor |
C |
| Wigeon |
Anas penelope |
C |
| Teal |
Anas crecca |
C |
| Pintail |
Anas acuta |
C |
| Goldeneye |
Becephala clangula |
C |
| Water rail |
Rallus aquaticus |
C |
| Marsh harrier |
Circus aeruginosus |
C |
| Bearded tit |
Panurus biarmicus |
C |
| Reed bunting |
Emberiza scheoniclus |
P |
| Swallow |
Hirundo rustica |
C |
| Sand martin |
Riparia riparia |
C |
| Greylag goose |
Anser anser |
C |
| Fish |
Atlantic salmon |
Salmo salar |
C |
| River lamprey |
Lampetra fluviatilis |
C |
| Sparling/smelt |
Osmerus eperlanus |
C |
| Twaite shad |
Alosa fallax |
P |
| Higher Plants |
Common reed |
Phragmites australis |
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| Narrow-leaved eelgrass |
Zostera angustifolia |
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| Dwarf eelgrass |
Zostera noltii |
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| Marine eelgrass |
Zostera marina |
C |
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