Importance Of The Area

The Fleet Lagoon is situated in such a position with only a narrow entrance at Ferrybridge that it commands some unique physical conditions. The narrow entrance from Portland Harbour and the breakwaters which enclose the harbour lead to a double low tide within the Fleet area. Other physical factors which give the Fleet a unique environment are:

• The water temperature; The sheltering of Chesil Beach causes the water in the Fleet to be warmer in summer and cooler in winter than the surrounding sea.
• The water salinity; The lagoon shows a unique salinity gradient from Smallmouth to Abbotsbury.
• The substratum; The bed of the Fleet varies in its composition from organic silt formed from decay of Eel Grass in most of west Fleet, to sand at Ferrybridge and a pebble regime within the Narrows.

Flora

Marine algae, Eel Grass (Zostera) and Widgeon Grass (Ruppia) occur in rich abundance in the Fleet for much of the year. Zostera augustifolia forms extensive meadows over the bed from Lynch Cove to near Abbotsbury. Z.noltii is also found in the lower salinities of west Fleet in water depths that never exceed 1.0m. Widgeon Grass occurs only in the West Fleet from Works Cove to below Shipmoor Point. Other species of algae found in the Fleet include the rare Stonewort, green algae and alien Japweed. Along the shore of the Fleet there are three main habitat types:

• Saltmarsh; This is distributed all around the shore of the lagoon being best developed in inlets and bays and at the two ends of the Fleet. This supports Thrift, Shrubby Sea-blite and Sea Purslane.
• Freshwater marsh; These are found adjacent to some of the saltmarsh areas, e.g. off Pirates Cove. The best developed freshwater marsh is found in Abbotsbury embayment and the most significant plant species found there is the Marshmallow, also Water Cress and Fools water Cress.
• Coastal grass cliffs; The land shore of the Fleet varies from very low, gently sloping land to vertical or steep cliffs of 3-5m. These meadows support Common Couch, Bee Orchid, Common Centaury and Yellowwort.
• Shingle environment; Chesil Beach provides a habitat for many plants adapted to an unstable substratum. The Rarest of these being the Sea Pea, but also Sea Bindweed, Sand Couch and Sea Campion.

Marine Invertebrates

The Eel Grass community provides the main environment for a whole range of invertebrates over almost the whole of west and much of east Fleet. Also the high quality of water within the Fleet associated with the variety of substrates provide home for many marine invertebrates.

The tidal rapid system of the Narrows supports benthic communities on its unusual pebble regime. These include species of algae, sponge, anemone and Goby rare in the UK.

Other species such as sponges, anemone, starfish and asadian occur in exceptional abundance or sizes. Two important alien species occurring within the Narrows are the Slipper Limpet and the Japanese Seaweed.

These invertebrates are supported by the abundance of microscopic organisms within the water such as Copepods, Round, Flat, Ribbon, Smooth, and Hairy worms, Ostracods, Diatoms, Insect larvae and Protozoa.

Birds

Chesil Beach, the shoreline of the Fleet and the waters of the Fleet itself are very important to a large number of bird species. The area is used mainly by wintering flocks of waterfowl and waders and species on migratory passage. The area is also important to a lesser extent for breeding species. The most important breeding species is the Little Tern. The Chesil's present day population of Little Tern and to some extent Common Tern (except Scilly), and Ringed Plover (except pockets in north and south Devon), are the only representatives of their species in the south west peninsula.

The Fleet is a stop over point for many migrants due to its location as the most southern point of Britain. Brent and Canada Geese overwinter in the Fleet and many rare species are blown into shore or pass through such as Little Auk, Fosters Tern and Great Northern Diver.

Fish

The Fleet is a designated MAFF Bass Nursery and fishing from boats is therefore restricted. Other fish in the Fleet include large shoals of small Grey Mullet, Sandsmelt, Sandeels, Flounder, Rockling, Blenny, Wrasse, Pouting, and Stickleback.

Oysters have been harvested from the Fleet since the 15th century and there were commercial operations in 18th and 19th century. Today Abbotsbury Oysters Ltd. successfully breed, clean and sell the Pacific Oyster.