fbnature

The Chesil Bank is one of the five largest shingle beaches in Britain, whilst the Fleet is the largest regular tidal lagoon in Britain. Growing within the Fleet are two species of eel-grass Zostera spp. and two species of Ruppia, and these support an invertebrate fauna that is now extinct in many parts of Europe. The eel-grass is food for the largest resident mute swan population in Britain. For these reasons and many more, the Fleet and Chesil Bank have been designated as a Site of Special Scientific Interest of the highest grade, equivalent to a National Nature Reserve.

The Ferrybridge end of the Fleet and Chesil Bank differs from the other parts of this unique region. It includes the inlet/outlet of the Fleet called Smallmouth, and an area called the Narrows, through which the tide ebbs and flows, altering the salinity and tidal regime of the waters in the Fleet's lagoonal basin. Thus it creates two of the most influential factors governing the wildlife of the lagoon and its surrounding habitats. It is also an estuarine habitat of high marine biological importance in its own right.

The backbone of the natural complex around Ferry Bridge is Chesil Bank. This "narrow thread of land" as Thomas Hardy described it, that stretches away to the west towards Abbotsbury and beyond for nearly eighteen miles, is the only barrier to keep the peninsula of South Dorset from being swept away by the wild Atlantic seas. Chesil is a linear ridge of pebbles pushed up on a bed of clay by a rising sea at the end of the last ice age.

In geomorphologic terms Chesil Bank is known as a tombola - pebbles which have been size-graded all along the beach, the smallest stones being the pea-gravels found at West Bay, and the largest being the cobbles at Chiswell. The pebbles are of many different kinds, derived from a great variety of sources. Flint however is the predominant material.

The most widely accepted hypothesis about the origin of Chesil Bank belongs to the local geographer, Geoff Poole. An attempt is made to produce a simplified and shortened version of his theory here. Chesil's story began during the last glacial epoch, when Lyme Bay was dry and vast quantities of rock debris from land that surrounds the Bay, together with material from the pre-glacial shoreline, would have been carried out into the dry floor of the Bay by rivers formed during the brief summers, and as the climate slowly improved.

As the sea level gradually rose at the close of the last Ice Age this debris was moved inshore by the most dominant wave force which is from the south-west. The debris moved until it was trapped by the protrusion of Portland and as it piled up in the eastern part of the Bay - Chesil was formed.

As we know however, it was not a haphazard heaping of shingle, but a size-grading process which was initiated by those same south-west waves hitting the beach at an acute angle, and pushing material along the beach towards Portland. Confusing though it seems, the larger the pebble, the further and quicker it moves, as it offers relatively more resistance to the waves. Only when a pebble finds mates of its own size is its journey likely to end.

At Ferry Bridge, Chesil veers towards a more southerly direction, facing the storm waves more-or-less at right angles. Here the lateral movement of pebbles is considerably reduced, and there is more vertical movement as the occasional ferocious storm piles the pebbles up. It is here that the Chesil's crest reaches its maximum height, in excess of 14 metres, and this has a significant effect upon the nature of the Beach. Nowhere else is Chesil so compact, this consolidation being aided and abetted by the influence of water from Portland Harbour and the Fleet pushing fine sediments into its rear.

The beach flora at Ferrybridge reflects this stability. Areas of "close turf" have formed to the north, south and west of the car park, opposite the caravan park, and of course, there is a belt of continuous vegetation on the Hamm Beach. Although most of Chesil's typical shingle plants are present here, they are not obviously "zoned" like they are to the north-west, where the beach is more dynamic.

The species and distribution of the vegetation has been influenced by other factors, as well as soil compaction. The larger pebbles must have some effect on the specialised root systems of the shingle plants. Certainly some of them, like the Sea Pea, Lathyrus japonicus, which is present but does not flower here, seem to perform less well, and others are poorly represented. One shingle species that does like the Chesil at Ferrybridge is Common Storks-bill, Erodium cicutarium. On that "bare" wide stretch of shingle between the Butts and Nantes Hut, this beautiful low-lying purple geranium thrives.

Nevertheless, despite the poor zoning and showing of the shingle flora, the Ferrybridge area contains the highest species count for any comparably sized area on Chesil, and this is due to the richness of these mats of turf, valued so much by the visitor to ease his walk on the Bank. Here the halophytes - plants that can tolerate some degree of salinity in the soil and around their roots, as well as the effects of salt on their shoots - have been joined by species that are associated with dry calcareous grassland and waste areas.

Hare'sfoot Clover, Kidney Vetch, Thyme, Birdsfoot Trefoil, Restharrow, Darnel Grass, Sand Sedge and Rough Clover are just a few of the dry grassland species which have established themselves alongside the "seasiders". Practically all of these plants have a tiny but delightful form. Mid-April to mid-May is a special time however. This is when the turf is transformed into a carpet of thrift - literally a "sea of pink" and a sight that can surely have no rival in this region. Quite why these areas of turf are so distinctly separated is not fully understood. Perhaps the heavy use of the area as a First World War firing range, not only for shooting but also for exercising, might have been responsible. Certainly the trampling of vegetation by human feet continues to affect the distribution of vegetation all around Ferrybridge.

Another distinct and important plant community is the saltmarsh, that band of vegetation that runs along the Chesil on the higher foreshore and just above it. Shrubby sea-blite, Suaeda fruticosa, and Sea Purslane, Halimione portulacoides, are the two most obvious members of this group, and their contrasting shapes, forms, and green foliage, usually seen together, create a very distinctive shingle landscape feature. The saltmarsh gives cover to most of Chesil's mammal populations and its extensive and tight rooting system allows other plant species to take hold, but most importantly it minimises the shingle surge towards the Fleet, thus helping the Beach in its duty as a sea defence. The best example of saltmarsh at Ferrybridge is seen around the tidal creek and ponds which were created when shingle was extracted before the war, and hauled away by horse and cart to make concrete.

One of Ferrybridge's most interesting plants is the Four-leafed Allseed, Polycarpon tetraphyllum. This Mediterranean annual was first recorded at Smallmouth around 1750, but it has never been seen regularly. Before a recent sighting (1991) it was last seen by Dr. Coombs in 1946, and he never found it again despite looking for over 40 years! The plant occurs elsewhere in the wild, in one station in Cornwall and in the Scilly Isles.

Chesil is prized for its non-flowering plants. These are the lichens, mosses and liverworts that individually, or sometimes collectively, spread over the shingle. Undisturbed patches are quite extensive and scientifically very important. Like the flowering plants, they too are coastal specialists. It may seem astonishing to those who are not that familiar with the area, that several species of fungi may be found.

A surprisingly high number of insects have been recorded at Ferrybridge, obviously on days when the salt-laden winds are not attaining stinging speeds. They are principally attracted to the vegetation on the Chesil and Ham Beaches. There is an impressive list of moths including many migrants, and a selection of bees and grasshoppers. Occasionally a few butterflies are seen, particularly migrant Painted Ladies and Clouded Yellows, and there are records for Small Blue, Small Skipper, Essex Skipper, Marble White and Meadow Brown. One of the rarest insects at Ferrybridge is a beetle. It is known only by its scientific name, Omophlus rufitarsis. The beetle is found on Thrift, and before it was rediscovered in 1989 it was last recorded in 1926. It would seem that Ferrybridge is now the sole haunt in the whole of the British Isles for this beetle.

The vegetation cover at Ferrybridge is important for birds. Many migrating land birds are grateful for this cover, and perhaps a little food, to recuperate after their cross-Channel journey. Warblers hunt insects on the Shrubby Seablite, whilst larks, Wheatears, pipits and wagtails scour the turf. Some residents such as Skylark, Linnet and Meadow Pipit are able to find enough cover.

The shingle and vegetation is of special interest to sea birds and waders, not only as a high-tide roost, but also as a place to nest. Ferrybridge is the stronghold of Chesil's population of Ringed Plovers, the only breeding area for this species in the south-west Peninsula. In recent years it has attracted the bulk of Chesil's nationally important population of breeding Little Terns - up to 50 pairs breeding in the fenced-off area beyond the Butts.

Common Terns periodically breed at Ferrybridge, and there have been reports of other tern species nesting too. That well known local prawn fisherman, Alfie Warren, used to talk about Roseate and Arctic Terns nesting alongside the Commons. At the turn of the century there was a record of Sandwich Tern nesting. During the same period a female Sandwich Tern which had been shot, was found to have a well-formed egg inside of it, lending support to this record.

A mammal that people do not expect to see on Chesil is the hare, but it does live and breed quite happily on the beach. A perceptive observer may spot hare trails in the shingle along which nocturnal food forays are made from quiet daytime retreats further up the beach. Occasionally a young leveret may be found in the Shrubby Sea-blite. Remembering that this part of Chesil is part of Portland, careful reference is now made to that other local lagomorph - the bunny, or underground mutton! They are not common now, but they were - what is now the Beach Road car park was an ancient warren before it was transformed by United States Army engineers into an assembly point for tanks and transporters preparing for the D-day invasion.

The most commonly seen mammals at Ferrybridge today are rats and foxes, both thriving on the messy rubbish left by a minority of fishermen and other visitors, as well as the easy pickings available in the nearby urban community of Wyke Regis. Due to this extra food supply, their populations often increase out of all proportion to their available natural food. When these species make seasonal switches to their natural foodstuffs, there is just not enough to go round. Short-tailed Voles and Woodmice are plentiful in the vegetation and provide a meal for the Kestrels, when these birds aren't devouring tern chicks. Very occasionally the odd Badger and Hedgehog will wander up Chesil and more than once an early morning watcher has been rewarded with the sight of a Roe Deer quietly browsing on the turf.

Common Lizards seem inseparable from railway tracks, and sure enough lizards exist on the Ham Beach along the course of the old railway line. Was it the railway line that led them to the Ferrybridge in the middle of the last century, just as it did with those well known plant followers of the railway system - Oxford Ragwort, Senecio squalidus, and Common Toadflax, Linaria vulgaris. Adders are present on the land-shore of the Fleet, and people say they have seen them on the Chesil.

The Fleet Lagoon (or Backwater, or Littlesea as it is known locally) runs along the inner flank of the Chesil Bank and completes a coastal scene which many view as being one of Dorset's best. Certainly, when viewed from either the cliffs of Portland, or the hills of Abbotsbury, the scene is quite dramatic.

Like Ham Beach and Chesil Beach, the Fleet at Ferrybridge is another wildlife treasure chest. The Fleet was formed about 5000 years ago, slightly after the Chesil Bank. As the sea rose to its final level at the end of the last ice age, water seeped over the low lying land to the east of Portland and flooded along behind Chesil Bank. From recent borehole research it seems that initially this flooding was more extensive than it is now, and that the lagoon probably reached beyond West Bexington.

A natural silting up over many years has probably been the major factor contributing to the shape of the Fleet as we know it today, and it was a natural force that brought about the area's most dramatic change. The Great Storm of 1824 caused a tremendous quantity of sea water to surge up the Fleet and resulted in the destruction of small villages and loss of life. It also greatly widened Smallmouth, the lagoon's only exit to the sea. This must have released the organic silts trapped in the wider expanses of the lagoon behind its estuarine bottleneck.

But the scouring out was not to last for long, before artificial forces began to reverse the process. Within three decades material was dumped along the causeway to restore Smallmouth Passage to its former dimensions, and the Portland Breakwaters were also beginning to significantly affect the tidal force and direction in the whole Portland Harbour, let alone around the entrance of the Fleet. Once again the mud-silts, washed into the Fleet by its feeder streams and down off the adjacent farmlands, were beginning to accumulate, and the mud-flats began to re-shape.

A detailed study in the 1970's of the Fleet's physical characteristics and natural history took account of the important hydrographic survey by the Central Electricity Generating Board, which was undertaken in the early 1960's following a proposal to site a nuclear power station near Tidmoor. Dr. John Whittaker's paper, "The Hydrology of the Fleet" contained the results of nearly a decade of further work on this subject, and by the time Dr. I. Robinson completed his studies on the tides, water levels, salinity structure and tidal flushing of the Fleet, scientific knowledge of the lagoon was beginning to take shape.

During the mid-seventies, the Fleet Study Group was formed and this small band of dedicated scientists planned future research projects. Inventories of the main animal plant groups were compiled. Dr. Elsie Burrows catalogued the many seaweeds (some very rare) and plotted their distribution in the Fleet, and Dennis Seaward did the same with the molluscs. Dr. Nigel Holmes investigated Zostera and Ruppia communities, and lesser works were carried out on fish, marine invertebrates, and birds.

A thorough examination of the sub-tidal communities of Ferrybridge was still to come however. The work of the Victorian collectors - and during the 1960's and 1970's of John Hawthorne - has revealed the richness in the plant and animal communities, but plans for the recent Ferry Bridge re-construction ensured that there would be no further delay in the investigation of the lagoon's "link channel", which runs from the "rapids system" known as the Narrows, to the lagoon's tidal exit at Smallmouth. Dr. Peter Dyrynda of the Marine Research Group of the University College of Swansea, began his diving survey in 1983. Peter Dyrynda knew from the work of Whittaker and Robinson that: "the link channel experiences a relatively normal tidal regime with a near full and regular cycle, but on the very small, approximately 1.5 metre range characteristic of the Portland area. Good flushing combines with a relatively stable, polyhaline salinity regime, according to records not falling below 25%. Strong tidal currents (but minimum wave exposure) are generated within the link channel, not only because it is the downstream section of the lagoon, but also a zone where flow is constricted ........A maximum tidal velocity of 4 knots has been recorded. The link channel is generally shallow, at less that 5 metre below chart-datum, and is floored by benthic substrates indicative of strong currents. Beds of gravel, stones and hard substrates characterise the Narrows and Smallmouth, whereas sands predominate within the intervening section where currents are relatively weak".

Dyrynda dived at fixed channel centre stations and made long-channel and cross-channel dives to collect data for his survey. He found the water clarity and light penetration good, not only after the flood but also the ebb tides, and that this, along with the high level of nutrients and good water flow, allowed favourable conditions for seaweeds and suspension feeding invertebrates to compete for space side by side.

He found that community structure within the channel varied primarily according to the strength of the water currents, which govern not only the nature of substrates, but also the maximum sizes of the organisms. Altogether, he identified a total of six differing communities within the area of Ferrybridge, as follows:

3) That associated with the pebble regime within the Narrows (pebbles originally rounded by the waves on the outer flank of the beach, and now transported by currents to form bars across the Fleet).

His survey identified the presence of unique habitats, communities, and rare species within the link channel, which adds to the overall significance of the Fleet and Chesil Beach. Of these sub-tidal species, Dyrynda mentions the algae Solieria chordialis and Gracilaria folifera, the sponge, Suberites massa, the anemone Scolanthus callimorphus and a goby, Gobius couchi, as being generally rare species within the UK, whilst other species, although less rare, occur in exceptional abundance or sizes, e.g. sponges in general, but particularly Halichondria bowerbanki, the anemone Anemonia viridis, the starfish Asterina gibbosa and the ascidian Phallusia mammillata.

Another important community not covered in this survey is the Sea Pen (Virgularia) community in the Portland Harbour sheltered mud beds. This is the only inshore community of its kind on the south coast of England.

Two important alien species occur within the link channel, and a third, the Pacific Oyster, exists in adult form on racks outside the Abbotsbury Oyster Farm. The slipper limpet, Crepidula fornicata, a well known community dominant, is not having any significant impact, but Japanese Seaweed, Sargassum muticum, did after its arrival in 1982. In spite of attempts at clearance, it increased substantially for a few years, and having such a phenomenal annual growth (up to 6 metres) it seemed on the verge of catastrophically affecting the ecosystem of the Fleet, and making life a misery for just about everyone using it. Undoubtedly it has changed the ecosystem structure of the link channel, but in very recent years it seems to have climaxed in its distribution, and possibly declined. Although it still has to be cut in the Army Training Area for units to be able to exercise properly, "Japweed" is no longer feared!

The replacement of the old Ferry Bridge over Smallmouth by a new bridge 200 metres to the south, the creation of a new channel, and the infill of the old, was a matter of concern for the Fleet lagoon as a whole, and the Ferrybridge area in particular. Some of the rare and local sea-slug, Aeolidiella alderi, that would be directly effected by the construction, along with other animals, were moved short distances to safer areas in November 1983, before excavation started.

In the main the marine invertebrates seem to have survived the new arrangements and although there was a decline in some populations shortly after the completion of the new bridge, it is likely that it was due to the very severe winter weather of January 1985. Obviously there was, and continues to be, some shifting of sediments from the new flood channel to the old, and this affects the Ferrybridge area in particular. Of greater interest for the Fleet as a whole however is that the volume of water in the lagoon overall seems to be greater.

At least twenty five species of fish have been recorded in the Fleet, and more in Portland Harbour. Commercially speaking, the most important is Bass, which comes as young fish into the Fleet to feed and grow. The Fleet has been designated as a Bass Nursery Area. Mullet are netted on a small scale at Ferry Bridge.

The Sand Smelt, Atherina presbyter, was studied in the Fleet in 1983 to gather information on its early life, following concern that vast numbers of this small shoaling fish were being lost in the intakes of cooling water at Southampton Power Station.

Sand-eel and goby populations form an important part of the terns' diet; in fact the Little Tern is locally known as the "potter" from the way it hovers around the shorelines, picking off unsuspecting fish by plunge diving from above. The variety of fish at Ferrybridge has attracted the attention of the Sea Life Centre staff, who have collected specimens for their viewing tanks.

An interesting crustacean which is of commercial value is the "Billy Winters". This shrimp invades the waters of the Fleet at Ferry Bridge in the wintertime and is caught in pots. Fishermen carefully throw the males back into the water - they represent only about 1% of the numbers caught and therefore every one has to be saved!.

Marine birds can be readily seen around Ferrybridge, particularly the Cormorant. In the winter a few unusual divers - Grebes and a very occasional Auk - fish the waters, and spring is best for watching the area's important population of Red-breasted Mergansers, as they indulge in a colourful courting ritual before leaving to breed in the North.

Incidental occurrences of larger marine animals include occasional Grey Seal, Halichoerus gryyptus, and Common Seal, Phoca vitulina, almost always regrettably individuals in some form of trouble. There was a time when Otters travelled up the Fleet, and - causing quite a stir in the summer of 1987 - was the appearance of the large jellyfish known to fishermen as "bells". It was the jellyfish Rhizastoma octopus and scores were washed up on the Ferrybridge shoreline. Hot summers may be the reason for this animal's appearance on the British coast.

The water's edge fascinates many people and once again there is plenty of interest at Ferrybridge, where the shores consist of four main character types - the clays of the land shore, the sandy shores and banks of the Fleet and Portland Harbour to the north and south of the Fleet exit channel, and the stony shore of the Hamm Beach.

The Wyke shore of the Fleet is most rewarding from a geological point of view. It is in fact a former coastline which was created approximately 135 million years ago, in a fairly shallow tropical marine environment. The present-day tides that wash these "Lower Kimmeridge Clays" constantly reveal the remains of marine creatures long extinct, including reptile and fish remains and more commonly, marine molluscs.

A curious insect that lives in "burrows" in the sand, and produces miniature "lug-worm like" casts - but only in the middle and not the lower shore zone - is a beetle called Bledius spectabilis. The burrow is constructed in such a way that air is locked in when the burrow is covered by the tide. This beetle relies on its sense of smell to find its mate!

Another creature that survives in airlocks - but in the chinks of pebbles - is even more extraordinary. It is the Scaly or Wingless cricket, Mogoplistes squamiger. This creature, which only exists at Ferrybridge in the UK - and just two other sites in the world, one in Italy and one at Granville on the north coast of France - is thought to be very primitive. It has failed to evolve wings like other crickets and grasshoppers, and therefore lacks mobility. Its populations have become isolated and it is therefore ultimately doomed. The following interesting theory has been put forward which connects the three sites in which it survives:

"After the expulsion of the Axis forces from North Africa in World War II, the Allies turned their attention first to Sicily and then to the western shores of the Italian peninsular. Many of the invasions were made from landing craft. As these craft approached a beach with their bow-ramp lowered, all manner of littoral material, including (possibly) the Scaly Cricket at any stage of its life cycle, was scooped up.

There was a grave shortage of these landing craft and those used for the Italian landings were rapidly transported to Britain for the "Overlord" assault in June 1944. They were stored at Portland Harbour, only a matter of a few hundred yards from Smallmouth. After June 1944, as the Allied armies pushed eastwards, these forces were supplied from many south coast ports including Portland. Perhaps very significant is the fact that Granville was, well into 1944, the base of the Supreme HQ, Allied Command.

It seems reasonable but unprovable that the Scaly Cricket was carried from the Mediterranean, possibly from the western shore of Italy, to Portland Harbour in landing craft. It is possible that some were then carried, again probably by landing craft, to Granville with men and material for the Allied HQ".

One of the inter tidal area's most sought after creature is the Lugworm, Arenicola marina. Anglers dig into the sand to find these worms for bait. In 1985 however, the population suffered enormously, with thousands upon thousands being found dead on the surface of the sands. A "red tide" of over-rich plankton had deprived the worms of oxygen, but the lug worm proved to be a rapid re-coloniser and the population soon recovered.

The worms and other invertebrate animals in the sandflats are food for the gulls and waders, which can be seen in some numbers throughout the year, but the spring and autumn migrational periods are best. Ferrybridge offers the only refuelling point between Poole Harbour and the Exe Estuary for these sand-probing birds. Oystercatcher, Turnstone, Dunlin and Ringed Plover can nearly always be seen, and regular visitors include Sanderling, Curlew-sandpiper, Greenshank, Grey Plover, Whimbrel, Curlew, Bar-tailed Godwit and others. A new regular winter visitor is the Brent Goose. Since becoming a protected species, the Brent's population has increased, and although most of the Fleet's flock are to be found on the eel-grass beds and to a lesser extent on adjacent fields of winter cereals, up to 300 fly nearly daily to Ferrybridge to feed on the saltmarsh and the inter tidal green seaweed.

Ferrybridge is the best place in the country for seeing the Kentish Plover, and other unusual waders and gulls are always likely to turn up. For this reason the area is surveyed intensively by local birders - even if it is only for ten minutes during their lunch breaks!

Britain has 29% of the estuarine resources of the North Sea and Atlantic coasts of Europe, and two thirds of these occur in England. Almost one third of the total area of Sites of Special Scientific Interest (SSSI) notified in this country cover estuaries. The Fleet Lagoon represents approximately 90% of the country's saline lagoon systems, and is considered to be the country's most unpolluted body of coastal water. Its importance for coastal conservation cannot be over-rated, despite its small size, for it encompasses four major natural sites and many important coastal habitats.

The Ferrybridge area has been successfully used by marine, industrial, and commercial concerns, along with the Navy, without too much detriment to the natural environment. More recently it has become a popular base for numerous sports and recreations, renowned in particular for sail-boarding, angling and diving. It will increasingly become a greater attraction for the growing number of visitors who want to explore the coastal landscape.

It must be acknowledged that the natural history qualities of Ferrybridge are not always obvious. Many people see this part of the coast simply as a desolate, windswept area sandwiched between Wyke Regis and the Royal Naval Air Station. The key to the successful management of Ferrybridge is therefore seen to be in the provision of good interpretation and information to obtain the understanding and co-operation of the general public.

There is a small exhibition of Ferrybridge wildlife at the Reserve's cabin on the Chesil Beach car park. Why not pay a visit and please ask to join the "Friends of the Chesil Bank and the Fleet Nature Reserve" to help preserve this very special site.

I stood upon the mighty Chesil Bank,
For mile on mile the sea churned pebbles ground.
Each stone a boulder was before it sank
But waves and time have made them pebbles round.
Each man is born a sharp and ragged stone,
Life knocks the corners off us all, until
Into our own appointed place we're thrown
With others, yet an individual.
Perhaps it is a cosmic counting frame,
Each pebble scores the life of one good man.
The Tally Roll of Heaven. In God's game
A marker for each one who kept to plan.
It wasn't just a shingle beach I trod,