| Fringing
the north-eastern shores of the Irish Sea, the coast of Lancashire and North Merseyside
is mainly low-lying - apart from some small cliffs around Heysham and Silverdale
- and its shore has a comparatively large tidal range for the British Isles. The
coast is divided by large estuaries: those
of the River Mersey and the River Ribble, which flow into Liverpool Bay; and of
the rivers Keer, Lune and Wyre, which flow into Morecambe Bay along with the Kent
and Duddon in Cumbria. It is dominated along most of its length by sand
dunes, salt marshes, mud flats and sand
flats. Large
areas of tidal salt marsh, mud flat and
sand flat were claimed from the seabed
for farming over the 19th and 20th centuries, with the incoming tide held back
by embankments and pumping stations now maintained at public expense. Others were
lost to urban development around Liverpool and Morecambe. Similarly,
large areas of sand dune have been lost to
urban development, particularly around Blackpool and Southport, where engineered
coastal defences have been built and maintained for over a century to protect
the structures. As
sea levels rise and storms become more frequent, these wildlife habitats are becoming
squeezed between the rising tide and the walls of the artificial embankments. Between
the tides, sand flats that are not disturbed by waves and tidal currents may have
an abundance of marine animals including lugworms, ragworms, edible cockles, crustaceans,
Baltic tellins and peppery furrow shells. These provide rich feeding grounds for
fish, waders and wildfowl. Smaller areas of mudflats are found at the head of
the river estuaries. The reduced salinity there results in slightly different
communities of animals dominated by the tiny Laver
Spire Snail (Hydrobia ulvae). | 
