Breadcrumbs
East of England Undersea Landscape
From the Humber to Kent the underwater landscapes of Eastern England include great plains of sands and gravels which creep southwards in the currents, ranged over by plaice, rays and other fish. There are also wave-cut chalk gullies and reefs such as those off Thanet and Sheringham, home to many types of crab, sea anemone and sponge. Herring spawn on gravels in the Thames Estuary, colourful sea slugs and wrasse haunt wrecks and ‘white weed’ hydroids carpet muddier seabeds. Worms form vast living reefs in the Wash, where lobsters also burrow in sandbanks.
This area is home to:
- Large, flat, open plains used as hunting grounds by dog fish and thornback rays as well as seals, porpoises and the occasional dolphin.
- The ‘burning’ – a name given by the fishermen of North Norfolk to algae glowing with phosphorescence at night.
- Dogger Bank – a vast network of enormous underwater sand dunes, some as tall as Nelson’s column.
- The wonders of the seabed off the Suffolk coast, including colonies of striped venus clams and ‘heaths’ of burrowing brittlestars.
- More than 220 wrecks, dating from Anglo-Saxon times to the 21st century. Many have developed a rich wildlife similar to that of rocky reefs.
- The Sheringham Chalk Gullies – home to a fascinating variety of algae, sponges and anemones as well as lobsters and conger eels.
- Dense shellfish beds of cockles and mussels amongst the expansive mud and sand flats of The Wash.
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Panorama
Click the numbers on the image below to find out more about the diverse range of species and habitats.
1. Thanet chalk cliffs and caves
Chalk originally formed in the sea itself from microscopic organisms. It provides an ideal home for many forms of marine life - which find it easy to burrow into, get a good foothold on its rough surface or hide in the many fissures and cracks in the surface. Only 1 % of the British coastline is composed of chalk, yet this represents three-quarters of all chalk reefs in Europe. The underwater chalk reefs off Thanet on the North Coast of Kent are the largest continuous area of intertidal chalk in the UK.
The partially submerged caves around Thanet extend for up to 30m into the cliffs and reach 6-10m in height Some very specialised algae and lichen live in them. A few very hardy marine snails are found here, along with coastal relatives of woodlice. [back to panorama]
2. London
3. Sizewell nuclear power station
4. Cromer, North Norfolk
In summer the rich nutrients in much of the North Sea trigger massive growth of microscopic algae, which in turn are grazed on by an army of ‘zooplankton’, equally tiny animals. These form a gigantic buffet table on which all the wildlife of the North Sea ultimately depends.
At night, some of these algae glow brightly with phosphorescence – a phenomenon in North Norfolk known by fishermen in the past as “the burning”. Fishing boats coming back on a dark night would follow the glowing sea trail of the boat in front to guide them along channels. [back to panorama]
5. Donna Nook
Donna Nook on the north-eastern coast of Lincolnshire boasts one of the largest breeding colonies of grey seals in the UK.[back to panorama]
6. Humber Estuary
7. Honeycomb chalk reef – the honeycomb of holes are drilled by peculiar shellfish called piddocks which burrow into the soft chalk
The chalk at Thanet is especially soft and easily bored into by creatures such as the strange shellfish ‘piddocks’. Piddocks drill into the chalk as they grow, creating a honeycomb of holes. Thanet is the only place in Britain where three different types of piddock live. The reefs have a number of little-known underwater caves, and this is one of the few places off the East coast where you find the long brown seaweed kelp.
The chalk platforms extend offshore in a series of steps dissected by gullies. The chalk has an unusually rich flora of algae, some of which do not occur anywhere else in Britain and which actually bore into the chalk. One of these algaes forms distinct orange, brown and black coloured bands on the cliffs and caves. [back to panorama]
8. Cod shoal
Cod, along with plaice and sole, are an important commercial species fished in eastern coastal waters. [back to panorama]
9. Herring shoal
Out to sea from the Thames estuary there are large deposits of gravels washed there by rivers after the last Ice Age when glaciers melted and retreated northwards. These gravel banks provide the ideal habitat for herring to lay their eggs. In winter, large schools of herring move inshore from the southern North Sea and gather to spawn here. The eggs sink down onto the gravel where they stick and form large mats. One female can lay as many as 50,000 eggs. When the eggs hatch, baby herring drift with the currents until they are about 5 cm long. Then they cluster into large shoals and move back inshore where they spend their first six months sheltering in the Thames and Essex estuaries. The large concentrations of herring at certain times of year attract many predators such as haddock, cod, harbour porpoise, dolphins and many seabirds. The Thames herring fishery has a long history and is one of the only certified sustainable fisheries in UK waters. [back to panorama]
10. Maplin seagrass beds
The sediments of the Maplin Sands in Essex support large seagrass beds. Seagrass is a grass-like flowering plant with green, long, narrow, ribbon shaped leaves. Seagrass beds support a wide range of plants and animals, are important in stabilising sediment and are used as nursery areas for fish. [back to panorama]
11. Ross worm reef – colonies built by billions of worms which glue sand and shell fragments together into masses of tubes
The stable coarse, gravelly sand about 13 nautical miles east of Great Yarmouth supports areas of ross worm reef. The reef structures are composed of sand and shell fragments glued together by many billions of ross worms to form densely packed tubes.
Ross worms let out feathery fronds into the water, especially at night, to sieve microscopic plankton from the sea for food. The living reefs rise above the surface of the seabed forming a patchwork mosaic habitat which supports creatures such as branching seamats, starfish and marine worms, mysid and edible pink shrimps, flattened porcelain crabs, and both brown and the red-eyed velvet swimming crab.
This area is one of only a few known examples of well-developed ross worm reef in UK waters. There are very few in other European waters either. [back to panorama]
12. Sheringham chalk gullies – covered in red seaweeds, sponges, anemones and hydroids
Divers describe time in these wave-scoured onshore-offshore gullies as like “time in a jacuzzi”. The gullies occur where the North Sea meets the great chalk expanse that stretches from Dorset to Norfolk. At Sheringham the gullies which the sea has cut into the chalk have a sand and gravel bottom, interspersed with boulders and flint nodules. The ridges are covered in encrusting coralline algae (red seaweeds which build a limestone skeleton for themselves). The sides and bottom are cloaked in a close-packed mosaic of ‘animal turf’ including sponges, seamats, dahlia and daisy anemones and hydroids. The colourful peacock worm and the flower-like, coral worm are present. Squat lobsters and some small common lobsters can be seen in the chalk crevices and conger eels live in the deeper holes. [back to panorama]
13. Minke whale – a fast swimmer at 20 km an hour
Out to sea, particularly off the Humber estuary, various species of dolphins and, very occasionally, minke whales may be seen. Minke whales use the bristle-like plates in their mouths to sieve out small fish such as sprat and sand eels from the water. [back to panorama]
14. Mussel beds
Mud and sandflats support dense shellfish beds of mussels and, on sandier parts, cockles. These are important as food for large numbers of birds and fish. [back to panorama]
15. Sole nurseries
Almost all the way around the coasts of Lincolnshire, Norfolk, Suffolk and Essex there are gently shelving mudflats and sandy beaches, saltmarshes and creeks. These habitats and the sandy, gravelly seabed a few miles beyond them serve as a huge north-south nursery for baby sole.
The waters, warm and productive in spring and summer, provide the ideal place for baby sole to grow up and they can often be seen in the shallows, perfect tiny flatfish, only the size of your thumb. When adult, the sole spawns in specific areas across much of the Eastern Seas at depths of 40 – 60 metres. One such concentration of spawning is just north of the Humber.
Each female lays up to 500,000 eggs although very few survive. They drift like plankton until the young are 12 – 15 mm long, and then spend their early months in the shelter of estuaries and inlets. When larger, the sole move out to sea, living on the undersea sandflats, burrowing by day and hunting small crabs, shrimp and worms at dusk and dawn. [back to panorama]
16. Razorbills diving for fish
The razorbill, a medium-sized seabird, is black above and white below with a thick black beak which is deep and blunt. Razorbills forage for food by swimming underwater and feed on sand eels, sprats and herrings. [back to panorama]
17. Dolphin
Large predators such as common seals, harbour porpoise and occasionally dolphins visit the sand and gravel plains of this undersea region, preying upon various fishes. [back to panorama]
18. Cuckoo wrasse – a dazzling bright blue and orange fish
Cuckoo wrasse is one of number of fish found on the rocky reefs. The females are rose-pink or orange-red. The males have a blue striped head and back, with bright blue markings on the fins – the rest of the body and fins are orange. [back to panorama]
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19. Wrecks – numerous along the coast of Eastern England, most of them rich with wildlife
Concentrations of wrecks dating from Anglo-Saxon times to the twenty-first century occur along the coast of Eastern England, concentrated along the shipping lanes and sandbanks. The north and northeast coasts of Norfolk hold some 225 wrecks, mostly from the 20th century. Where these are not regularly covered and uncovered by shifting sands, many develop a rich wildlife similar to that of a rocky reef.
One such wreck is the World War II submarine HMS Umpire which lies in 20 m of water, 12 miles off Blakeney Point. The north side of the wreck is covered with hornwrack . Large numbers of plumose anemone are found alongside dahlia anemone, burrowing anemone, dead men’s fingers (a soft coral), sponges and light bulb sea squirts.
Crustaceans found on the wreck include velvet swimming crabs, brown (edible) crab, common lobster and the painted topshell (a very pretty seasnail). At the base of the wreck, common sea urchin, common and Bloody Henry starfish and sunstars are present. Fish found include long-spined scorpion fish, poor-cod, ballan wrasse and bib. A striking violet seaslug is also found here.
Other wrecks provide mini-oases of hard reef landscape in the middle of sediment plains, which enable rock-loving species more typical of the north, west and south coasts, to spread into this part of the North Sea. Off Weybourne for example, divers have found the tompot blenny, on the wreck Rosalie, a freighter sunk in 1915 by a German U-Boat. This fish is not normally found in the southern North Sea. [back to panorama]
20. Dahlia anemone – some as big as dinner plates
These large anemones have up to 160 short stout tentacles and are very varied in colour. They may be white, yellow, orange, red, blue, grey, purple and brown or a combination of these colours. Most commonly, dahlia anemones have a red column blotched with green/grey and a prominent pattern of red lines amongst the tentacle bases. There are numerous grey warts on the column to which gravel and shell fragments stick. When the tentacles are fully retracted, the body of the anemones can be almost obscured by these fragments. [back to panorama]
21. Sea slugs
Grey sea slugs usually live in inter-tidal areas and grow up to 12 cm in length. They have a characteristic white V-shaped mark on the front of the head and feed on a variety of sea anemones. [back to panorama]
22. Sea fir beds
Sea fir beds can be found on the more muddy bottoms of some of the Essex estuaries. Although sea firs look like plants, they are actually colonies of tiny animals which live within a shared structure. Sea firs are also known as hydroids, and are static relatives of jellyfish. They stick up into the water column and feed on suspended organic matter and particles. [back to panorama]
23. Venus clam beds
Venus clams are found buried in sand and mud and have a thick, triangular shell with many fine concentric ridges. The shell is off-white or cream in colour and often tinted pale yellow. [back to panorama]
24. Heart urchins – also known as sea potatoes
Here, the underwater sand banks could be nicknamed the ‘sea potato hills’ because they are home to large numbers of the heart-urchin or sea-potato. [back to panorama]
25. Plaice spawning on the sandy seabed
Plaice are typical flatfish, oval in shape and often seen on sandy patches in rocky areas. They have bright orange or red spots on the upper side and spend much of their time lying quietly on the bottom, often partly buried. They can change their colour to camouflage themselves. They feed on brittlestars and sand eels and are an important commercial fish. [back to panorama]
26. Thornback rays hunting over the undersea sand dunes
The large flat open areas or plains are used as hunting grounds by predators such as the dog fish and thornback ray.
Thornback rays search out the many shrimps, worms and crabs that live in the sand. They often move closer inshore during winter and spring. The body of the ray is covered with coarse prickles as well as large, backward-pointing thorns (called bucklers), each of which has a thick button-like base. [back to panorama]
27. Lobster
Starfish , crabs and lobsters live all across this area, particularly on stonier ground.
Although European lobsters are generally associated with rocky reef areas, some lobsters burrow into the sandbank slopes of the central Wash. [back to panorama]
28. Dogfish – a shark which sleeps on the sandy seabed during the day and hunts during the night
These small, shallow-water sharks have blunt heads, slender bodies and two dorsal fins towards the tail end of the body. Dogfish can grow up to 1m in length. The upper surface of their body is greyish to pale brown with small dark brown spots, and the underside is creamy-white. They hunt across the sand and gravel plains. [back to panorama]
29. Sand eels - fish which burrow in the sand to escape predators
The countless millions of silvery sand eels feed on zooplankton (minute grazing animals) and they, in turn, support larger fish such as mackerel, cod, whiting, plaice and sole. [back to panorama]
