Tayside Biodiversity - Tayside Biodiversity Action Plan - Coastal - Estuaries
NATURE CONSERVATION IMPORTANCE
Sub-tidal zone

Estuaries have extensive underwater habitats in the sediments supporting a variety of algae (including seaweeds), plants, invertebrates and fish, which in turn support species further up the food chain such as seals and birds. These areas are also important nursery grounds for young fish.

Mudflats
Mudflats are highly productive areas which, together with other intertidal habitats, support large numbers of predatory birds and fish. They provide feeding and resting areas for internationally important populations of migrant and wintering waterfowl and are also important nursery areas for flatfish. Mudflats are characterised by high biological productivity and abundance of organisms, but low diversity with few rare species.
Seagrass Beds
Three species of Zostera occur in the UK and all are considered to be scarce: Dwarf eelgrass Zostera noltii, Narrow-leaved Zostera angustifolia and Marine eelgrass Zostera marina.

All three species are found in Tayside: the largest area being in Montrose Basin. The
plants are an important source of organic matter and provide shelter and a surface for
attachment by other species. Eelgrass is an important source of food for wildfowl,
particularly Brent goose Branta bernicia and Wigeon Anas penelope which feed on intertidal beds. The shelter provided by seagrass beds makes them important nursery areas for fish, including Pollack Pollachius pollachius, Twospotted goby Gobiusculus flavescens, Pipefish species and various Wrasse.

Swan Management Demonstration Project - Montrose Basin

Mute swans Cygnus olor are present in nationally important numbers on Montrose Basin; the
wintering flock consists of approximately 260 birds. They feed mainly on the Zostera beds in the Basin and move onto the adjacent arable land in December when the density of the Zostera is reduced. Attracted to fields of oilseed rape, cereals and grass, they cause damage to these crops by feeding and ‘puddling’ the fields with their feet.

To keep the swans off the arable land, a Swan Management Demonstration Project was set up in 1998 to provide an area of arable crop adjacent to Montrose Basin as a safe haven for them to feed in. A Swan Scarer is employed for several weeks during the winter to ensure the birds use the correct field.

The Project is a partnership between four of the local farmers, Angus Council, Scottish Executive Environment and Rural Affairs Department and Scottish Natural Heritage, together with the British Association for Shooting and Conservation, the National Trust for Scotland, Scottish Agricultural College and the Scottish Wildlife Trust.

Saltmarsh
Saltmarshes form the upper vegetated parts of intertidal mudflats. They are built up by a community of salt tolerant plants and are an important resource for wading birds and wildfowl. They act as high tide refuges for birds feeding on adjacent mudflats, as breeding sites for waders, gulls and terns and as a source of food for passerine birds particularly in autumn and winter. In winter, grazed saltmarshes are used as feeding grounds by large flocks of wild ducks and geese.
Mammals
There is a population of approximately 650 Common seals Phoca vitulina in the Tay Estuary which represents over 1% of the total European population and is therefore of international
importance. Otters Lutra lutra are found in both the Montrose Basin and Tay Estuary, but only anecdotal evidence is available as regards their distribution and population numbers as there is little existing data to call upon.
Birds
The expansive mudflats and tidal nature of the Tay Estuary and Montrose Basin are attractive as safe roost sites for geese. Other bird species are attracted not only by the safety, but
also by the food supplies available. Waders feed on a range of invertebrates whilst Wigeon and Mute swans at Montrose feed primarily on Zostera. Montrose is a nationally important
moulting site for many of Tayside’s Mute swans.

Both Montrose Basin and the Tay Estuary support nationally and internationally important populations of wildfowl and waders. This is recognised by their designation as Special
Protection Areas (SPA) under the European Birds Directive and as Ramsar Sites under the Ramsar Convention.

Nationally and Internationally important waterfowl populations wintering on Tayside Estuaries
Species Estuary International Importance National Importance
Mute Swan
Montrose Basin
/
Pink-footed Goose
Montrose Basin
Tay
/
/
Greylag Goose
Tay
/
Shelduck
Montrose Basin
/
Widgeon
Montrose Basin
/
Eider
Montrose Basin
Tay
/
/
Goosander
Montrose Basin
Tay
/
/
Knot
Montrose Basin
/
Bar-tailed godwit
Tay
/
Redshank
Montrose Basin
/
Sandwich Tern
Tay
/
Common Tern
Tay
/
Arctic Tern
Tay
/
Species for which the two estuaries are locally important include Oystercatcher Haematopus ostralegus, Golden plover Pluvialis apricaria, Sanderling Calidris alba, and Black-tailed godwit Limosa limosa. Montrose Basin holds a large latesummer tern roost which has numbered in recent years over 2,000 mixed terns including Sandwich Sterna sandvicensis, Common Sterna hirundo and Arctic Terns Sterna paradisaea.

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