Shingle beaches make up much of the world’s coastline. Some of these are shifting and unstable, giving opportunities for only the hardiest species to survive, but others are more permanent and support large plant and animal communities.
Shingle beaches are home to many different species. The Oystercatcher, Ringed plover and Black-headed gull may be seen nesting on the beach, while rabbits, hares, and foxes can be found trying to get an easy meal. Many different plants grow on and around the fringes of a shingle beach, giving a home to many other small insects.
Even on a calm day, the shifting stones at the sea’s edge indicate the tremendous forces which pile up shingle banks and build spits, bars, and promontories, which are such distinctive coastal features.
Some shingle shores are continually altered by the movement of the sea, while others are less affected by waves or tides and can become a stable feature of the coastline. With stability, more opportunities arise for plants to establish themselves, which creates conditions for more animal activity.
Large stretches of shingle foreshores are too mobile to support plant life. Others are stable during the relatively calm period between spring and autumn to allow summer annuals such as orache Atriplex to germinate and grow in the strand line, using the humus derived from rotting seaweed and other vegetation.
No higher plants can colonize shingle unless there is some rudimentary soil, which may be a mixture of sand, silt, animal droppings, and decomposed plant remains. The first remains are likely to consist of dead seaweed or salt marsh plants.
Where beaches have some soil and are relatively stable, colonizing plants such as the horned poppy and sea kale help to make the shingle more stable. Their long roots hold shingle together, and foliage forms a cushion shielding the pebbles from the waves. Sometimes an extensive carpet covers the shingle, made of such species as sea pea, sea campion, sea beet, biting stonecrop, and curled dock.
A true specialist of shingle is shrubby sea-blite, its bushy growth supported by a woody stem. Even when buried by the movement of shingle, it sends out new shoots and roots. Sea sandwort can also recover after being buried. Perennial plants such as these usually need the relative shelter of a landward position to reach full development.
While many species of land birds use the mature vegetation of stable shingle, the sparsely vegetated shores are mainly the home of maritime birds. Oystercatcher, ringed plover, and black-headed gull can be seen nesting.
Common, Arctic, and Little terns are colonial breeders and lay their eggs in shallow depressions in the shingle, often with only a few scraps of vegetation for a lining.
In winter, a flock of snow buntings may be seen picking up seeds and insects. Turnstone and purple sandpipers are commoner winter visitors who feed in mixed flocks along the strandline.
Rabbits may be so common on the shore that their numbers reach pest proportions, and it is not unusual to see brown hares slowly moving among the plants. Heavy grazing by these animals can damage and degrade the vegetation cover so much that even stable shingle begins to erode.
Foxes are often seen along shores. Foxes will hunt wherever they may find small mammals or nestlings and can often be seen among gull and tern colonies.
The grey seal can also be seen hauling itself out on a shingle shore to rest between feeding, give birth, and suckling its pup.
Life On The Tide
The area between high and low tide marks on an exposed shore supports little life as the breaking waves constantly grind and pound the shingle. However, the high tide strand line provides a habitat for sandhoppers, insects, and other invertebrates.
On sheltered shores, the beach material is less mobile, and various plants and animals colonize the shingle between high and low tide levels. The upper surfaces of larger stones may be covered by the pink encrusting alga Lithothamnion and the red seaweed Chondrus crispus.
The stones at the bottom of the shore may provide sufficient anchorage for large seaweeds such as the kelps, serrated wrack, and sea oak. If muddy gravel dominates, the bootlace weed Chorda filum and the green Enteromorpha are often common.
Where there are plants, there are usually animals, and the algae often house small gastropod snails and crustaceans. Tube worms and acorn barnacles live cemented to the stones, while mobile animals such as whelks and limpets keep a firm hold using their feet.
Empty whelk shells serve as a home for the common hermit crab, a scavenger that often occurs in enormous numbers on shingle. Some areas can be so densely populated with small green Psammechinus urchins that walking without treading on them can be difficult.
Types Of Shingle Beach
The commonest shingle feature is the fringing beach, familiar to holidaymakers, and is formed when the sorting action of waves and tides deposits a bank of pebbles.
The three other major types of shingle beaches are the shingle spit, the shingle bar, and the apposition beach.
Where waves indirectly hit a beach indirectly, carrying pebbles along the shore, and the coastline turns landwards, shingle deposition may continue in a straight line, forming a shingle spit.
A bar or barrier beach results if the spit formation continues across a bay to join the opposite shore.
An apposition beach occurs when shingle is deposited against an existing beach, then driven landwards by storms and piled into a ridge above the normal reach of waves.
What Is Stable Shingle?
The stable parts of large shingle formations are sometimes covered with a continuous sward of vegetation. Although many plants are not strictly maritime, the communities may be similar to those found on stable dunes and clifftops.
One community of the stable shingle which may develop on apposition beaches on the Channel coast is known as dwarf heath, its dominant species being ling and bell heather.
Eventually, stable shingle may be invaded by gorse, bramble, and other scrub species and may even produce holly wood.
Shingle shores may appear resilient, but heavy recreational use and motor vehicles quickly erode the thin cover of vegetation. Human disturbance is also a major factor in the decline of shingle birds.
Conservation management is achieved by controlling access and use to these areas and these may need to be closed for some time for bird colonies and vegetation to grow back.
Care and protection are required to ensure that this fascinating and valuable resource is not in the future restricted to just a few nature reserves worldwide.