Life on the Shore

 

The marine life on the shore varies from high to low water mark, as well as being affected by its composition, by tides, currents and waves.

Sheltered areas tend to have muddy shores, often with a fringe of saltmarsh at high water. This is best developed in the Comber Estuary.
Mud snails, which graze on microscopic algae and bacteria on the surface of the mudflats, are eaten by shelduck and other waterfowl.
Lugworms, ragworms, catworms, tellin shells and burrowing amphipod 'shrimps' live within the sediment.
These animals exist in enormous numbers and form an important part of the diet of the 45,000 wading birds which winter on Strangford Lough.
Muddy sand may be clothed with extensive beds of eel-grass, (a marine 'pondweed'), or with green seaweeds where there is enrichment from freshwater run-off.
These plants are the main food item for up to 15,000 grazing waterfowl, particularly light-bellied brent geese from Arctic Canada and wigeon from Iceland and Russia, which come to the Lough in winter.
Areas of gravel may support dahlia anemones, burrowing sea-anemones of several species, also worm-cucumbers, the extraordinary parchment worm and unusual creatures such as acorn and sipunculid worms. In sheltered lower-shore areas, larger cobbles embedded in gravels support exceptional growths of sponges, sea-squirts and tube-dwelling worms.
Sea-slaters and sand-hoppers live under cobbles on the upper shore where small winkles graze.
Further down cobbles and boulders are usually smothered in brown seaweeds (wrack), with a range of smaller red seaweeds including dulse and carragheen at low water.
Barnacles and chitons adhere to the upper surfaces, with several species of sponge, sea-anemone and sea-squirt round the base of the stones and on the wrack.
Periwinkles, whelks and top-shells, notably a white variety of the painted top-shell, saddle-oysters, green and edible sea-urchins, cushion-stars, sea-slugs and various worms are found near low water.
Redshank and turnstones feed in this habitat. Large boulders and bedrock are conspicuously zoned with colourful lichens at the top, a series of wrack species mid-shore and kelp at the bottom.

There may also be bands of barnacles, limpets and mussels, especially on exposed shores south of the Narrows. where many species normally confined to below low water can be seen on the shore. These include several types of sponge, soft corals, sea-squirts, sea-anemones such as the colourful jewel anemone, Devonshire cup coral and the curious sea-lemon (a large sea-slug).
A special feature of the Lough is its tidal rapids. Here a flow of salt water, even at low tide, allows underwater species such as feather-stars, sea-cucumbers and colonial sea-squirts to thrive on the shore.
To the north of the Narrows on the Outer Ards broad rock platforms with rockpools support a great range of red seaweeds.