information on the biology of species and the ecology of habitats found around the coasts and seas of the British Isles

Physiographic features

  Definitions (derived from Hiscock, 1996)
Open Coast Any part of the coast not within a marine inlet, strait or lagoon, including offshore rocks and small islands. This includes MNCR types; linear coast, islands / rocks and semi-enclosed coast (Hiscock, 1996).
Offshore seabed Seabed beyond three miles (5km) from the shore (Hiscock, 1996). 
Strait/Sound Channels between the mainland and an island or between two islands which are open at both ends to the open coast (it does not refer to similar features or narrows within marine inlets) (Hiscock, 1996). 
Sea Loch/ Sea Lough Glacially formed inlets (fjords, fjards) of western Scotland and Ireland; typically elongate and deepened by glacial action with little freshwater influence. Often with narrows and sills dividing the loch into a series of basins (see Hiscock, 1996). 
Ria/Voe Drowned river valleys of south-west Britain (ria) and Shetland (voe). Often with a greater presence of rock and more marine in character than estuaries (Hiscock, 1996). 
Estuary Downstream part of a river where it widens to enter the sea; often with significant freshwater influence and predominantly comprising sediment habitats (Hiscock, 1996). 
Isolated Saline Water (Lagoon) Enclosed bodies of water, separated or partially separated from the sea by shingle, sand or sometimes rock and with a restricted exchange of water with the sea, yielding varying salinity regimes (Hoscock, 1996).
Enclosed Coast / Embayment Any other sort of enclosed coast not covered by the definitions above such as harbours or marinas (Hiscock, 1996).


  • Hiscock, K. (ed.), 1996. Marine Nature Conservation Review: rationale and methods. Peterborough: Joint Nature Conservation Committee. [Coasts and seas of the United Kingdom. MNCR series.]