The Ribble Estuary is where the River Ribble, which originates in the Yorkshire Dales some 68 miles away to the east, meets the Irish Sea on the North West Coast of England between Southport and Rossall Point at Fleetwood, and upstream to Preston.
The estuary is tidal and is where salty seawater mixes with fresh river water. This causes the sediments carried down river and those brought in from the sea to mix and settle out as fine particles of sand and silt to form inter tidal sediments including both sand and mud flats. Tidal motion is essential in this mixing process and results in the formation of extensive sand and mud deposits across the mouth of the estuary and also within. These vary considerably according to wave energy and salinity levels with sand deposits tending to occur at the mouth of the estuary where energy levels are highest and mud deposits further upstream in less turbulent waters.
Sediment and salinity levels are also important for the development of salt marshes, within the inner most parts of the estuary, especially above the mean of high spring tides where salt tolerant plants are able to get a foot hold and grow between tides.
The shape of the estuary has changed over the centuries through natural processes and human influences. The most significant changes however occurred during the nineteenth century following the construction of Preston Docks, a walled shipping channel and dredging activities. This work narrowed and deepened the course of the river downstream of the docks and allowed the reclamation of large areas of former saltmarsh, foreshore and mudflats particularly at Hesketh Bank.
The estuary is the heartbeat of the surrounding eco-system, the ebb and flow of the tide creating habitat and supporting life. The brackish water of the estuary provides an important habitat in its own right. A multitude of wonderful sea creatures may be found including porpoises, grey seals and turtles.
The Ribble Estuary is a ‘slough’, or shallow water estuary, where large areas of inter tidal sediments or flats become exposed during low tides. Flat fish such as sole and flounder (or fluke) are common within such waters, while salmon and sea trout use the estuary to acclimatise to brackish water before swimming up stream to spawn or moving back out into the Irish Sea as young adult fish.
Commercial and recreational fishing is popular, with flat fish being the main catch for trawlers in the treacherous tidal currents of the estuary while cockling and shrimping are still popular on the sand flats of Horse Bank off Southport.
The mud and sand flats exposed during low tide also support millions of worms, snails and crustaceans providing a rich source of food for birds.