Area: 128.7 hectares.
Cornwall Area of Outsideing Natural Beauty and Cornwall Heritage Coast. Site boundary amended by extension and deletion. Mainly National Trust owned.
Description and Reasons for Notification:
Loe Pool, located south of Helston on the South Cornish coast, is the largest freshwater lagoon in Cornwall covering an area of approximately 50 hectares and with maximum depth of 6 metres. The underlying rock is composed of Devonian shales and siltstones, locally overlain by head deposits. Soils developed over the surrounding area are mainly acidic brown earths.
Both the pool and the shingle bar provide scarce habitat not found elsewhere in Cornwall, with rare species of higher plants, bryophytes, and algae, together with many rare and local insect species. The area is also important to wintering birds.
The pool supports several locally rare aquatic plant species including six-stamened waterwort Elatine hexandra, perfoliate pondweed Potamogeton perfoliatus, shoreweed Littorella uniflora, horned pondweed Zannichellia palustris, and amphibious bistort Polygonum amphibium. One noteworthy species of alga, stonewort alga Nitella hyalina, has also been recorded. The shingle bar supports local plant species including sea holly Eryngium maritimum, sea fern-grass Catapodium marinum, yellow horned-poppy Glaucium flavum, sea sandwort Honkenya peploides, sea mayweed Tripleurospermum maritimm, and the very rare strapwort Corrigiola litoralis.
At the northern inflow area is an extensive area of willow carr, mainly grey willow Salix cinerea, with common reed Phragmites australis locally dominant within the willow. There is a wide fringe of reed around the northern border of the lake. An area of relatively undisturbed ancient oakwood, mainly pedunculate oak Quercus robur, occurs in the west of the site. Areas of maritime grassland occur along the cliff edge with red rescue Festuca rubra forming an extensive mat. Other species include thrift Armeria maritima, wild carrot Daucus carota, wild thyme, Thymus polytrichus, spring squill Scilla verna, and western clover Trifolium occidentale.
Loe Pool is the only known site in Britain for the Cornish subspecies of the sandhill rustic moth Luperina nickerlii leechi, which feeds on sand couch grass Elytriga juncea. Nine species of Odonata, including the keeled skimmer Orthetrum coerulescens have been recorded here. The nutrient rich status of the pool has encouraged an abundance of benthic invertebrates, and there are also many rare or local species of Coleoptera and Hymenoptera. Loe Pool has the only recent record in Cornwall of the rare woodlouse, Porcellio dilatatus.
Loe Pool supports nearly 80 species of wintering birds with up to 1,200 wildfowl. Numbers of shoveler Anas clypeata can reach nationally important levels and regionally important counts of teal Anas crecca are not unusual.
There are also high counts for pochard Aythya ferina, tufted duck Aythya fuligula, mallard Anas platyrhynchos, goldeneye Bucephala clangula, gadwall Anas strepera, and coot Fulica astra.
Several rare birds have been recorded here in winter and on autumn migration. There is a breeding colony of about 20 pairs of sand martins Riparia riperia a species not well represented in Cornwall.
Loe Bar encloses a lagoon occupying part of a former ria, and forms an integral part of a beach system extending from Porthleven to Gunwalloe.
The site is important for coastal geomorphology on two accounts. First, Loe Bar is a classic coastal landform; and second, the beach system is an essential member of a suite of major beaches formed and maintained by predominantly south-west wave regimes. The beach is formed mainly of flint shingles and coarse sand. Current inputs from adjacent cliffs are small, and overall, the beach is in deficit. The Bar is washed-over during periods of high wave energy as demonstrated by a series of washover fans. The annually laminated sediments composed of classic material are unique in Great Britain.