List of saline lagoon Special Areas of Conservation in the UK

Lagoonal SACs in the UK are listed below in order around England and Scotland, starting in eastern England. There are no lagoonal SACs in Wales or Northern Ireland. Many of these SACs include a number of individual lagoons.

North Norfolk coast and Gibraltar Point Lagoons (Norfolk) A number of small percolation lagoons, eight between a shingle ridge (Blakeney Spit) and saltmarsh. The fauna of the lagoons includes nationally scarce lagoonal species the starlet sea anemone Nematostella vectensis and the lagoon shrimp Gammarus insensibilis. Other species of note include the relatively rare opossum shrimp Paramysis nouveli.

Benacre to Easton Bavents Lagoons (Suffolk) Percolation lagoons behind shingle barriers. They support a range of lagoonal vegetation types, including beds of narrow leaved eelgrass Zostera angustifolia in fully saline or hypersaline conditions, beds of spiral tasselweed Ruppia cirrhosa in brackish water and dense beds of common reed Phragmites australis in freshwater. The site supports a number of specialist lagoonal species including the anemone Nematostella vectensis .

Orfordness to Shingle Street (Suffolk) A series of percolation lagoons in a shingle bank. The fauna includes typical lagoonal species such as Cerastoderma glaucum, the ostracod Cyprideis torosa and the gastropods Hydrobia ventrosa and H. neglecta. The nationally rare starlet sea anemone Nematostella vectensis and lagoon sand shrimp Gammarus insensibilis are also found at the site.

Solent and Isle of Wight Lagoons (Hampshire & Isle of Wight) A series of lagoons at four locations mainly of isolated and sluiced types in coastal grazing marshes and behind sea walls. The lagoons have a range of salinities and substrata, ranging from soft mud to muddy sand with a high proportion of shingle. They support a diverse fauna including large populations of three notable lagoonal species: the nationally rare Lamprothamnium papulosum, the nationally scarce lagoon shrimp Gammarus insensibilis and the nationally rare Nematostella vectensis. Species diversity in these lagoons is high.

Chesil and the Fleet (Dorset) The Fleet is the largest example of a lagoon in England and has features of both lagoonal inlets and percolation lagoons. The lagoon is situated to landward of Chesil Beach, with a narrow entrance to the sea in Portland Harbour. It supports extensive populations of two species of eelgrass (Zostera noltii and Zostera angustifolia) and three species of tasselweed Ruppia, including the rare tasselweed Ruppia cirrhosa, and a diverse fauna that includes a number of nationally rare and scarce species. The eastern end of the lagoon is almost fully marine, with tidal narrows systems with rich and unusual fauna including sponges and anemones.

Loch Roag Lagoons (Lewis, Outer Hebrides) A complex of silled lagoons with a range of salinities, and a diverse range of habitats, including rocky outcrops, boulders and muddy sand, with softer mud in the inner basins, cobbles and shell gravel in the narrows. Beds of eegrasses Zostera spp. and tasselweeds Ruppia spp., turfs of marine algae and stands of large brown algae are present.

Obain Loch Euphoirt (Loch Eport obs, North Uist, Outer Hebrides) One of the most extensive and diverse systems of rock bound silled lagoons in the UK (with Loch nam Madadh). Consists of a complex of four lagoons, which together support the complete range of physical conditions and communities characteristic of this part of Scotland. Loch Obisary is unique among the brackish basins of the UK on account of its size, depth (over 40m), permanent hydrographic stratification and the range of communities it supports. Other lochs within the system support the nationally rare stonewort Lamprothamnium papulosum, beds of eelgrasses Zostera spp. and tasselweeds Ruppia spp.

Loch nam Madadh (Loch Maddy, North Uist, Outer Hebrides) Loch nam Madadh lagoons form the most extensive and diverse saline lagoon system in the UK, consisting of 10 lagoons, interconnected with freshwater lochans and the fjardic sea loch of Loch nam Madadh itself. There is a wide range of types from large, complex lagoons with several sills and basins, to single shallow lagoons, encompassing the full transition of salinity from freshwater to fully marine conditions. Rock bound silled lagoons in Europe are virtually restricted to the Outer Hebrides in Scotland. Most basins are floored with soft peaty mud, with boulders and cobbles, especially around the margins. At the entrances to some of the lagoons there are tidal rock and boulder waterfalls, or rock and coarse sediment rapids, or percolation barriers. There are beds of dwarf eelgrass Zostera noltii, small patches of Zostera marina and large quantities of the scarce green alga Cladophora battersii, and the scarce stonewort Lamprothamnium papulosum. Tidal rapids have kelps, calcareous maerl algae, and sea oak Halidrys siliquosa with rich epiphytic growths of sponges, ascidians and anemones.

Loch of Stenness (Orkney) A single basin with characteristics of silled lagoons and lagoonal inlets. It is the second largest brackish lagoon in the UK, and is of particular importance on account of its size, stability, reduced salinity regime and northern location. Lagoon bed is predominantly soft mud, with sand, gravel and pebbles around the margins. Mats of filamentous green algae occur, with large numbers of mostly marine/brackish infaunal and epifaunal species. Beaked tasselweed Ruppia maritima, the brackish fucoid alga Fucus ceranoides, filamentous green algae and the pondweed Potamogeton spp. occur in areas of lower salinity.

The Vadills (Shetland) A complex of eight interconnected shallow basins with characteristics of lagoonal inlets and rock-bound silled lagoons, encompassing fully marine to brackish conditions. Soft peaty mud forms the substratum in the basins, with narrows between basins with increased tidal currents supporting the calcareous alga maerl. Eelgrass beds Zostera marina and tasselweed Ruppia maritima occur in the sheltered basins, with rock tidal rapids supporting brown algae with rich associated epifauna. The site supports several unusual invertebrate species and communities, and the free living fucoid alga Ascophyllum nodosum ecad. mackaii, for which this is the northernmost record in the UK.

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