You look out to sea, and even on the calmest days you can detect the sinister presence of the Helwick Sands by a line of darker blue. Once the wind blows they break white with foam.
Wynford Vaughan-Thomas, Portrait of Gower
IT IS IMPOSSIBLE to adequately describe the natural history of a peninsula without including the surrounding sea. The underwater environment, however, is an unfamiliar one to many naturalists due to the difficulties of access and the lack of research compared to terrestrial habitats. Marine ecosystems are also much simpler than terrestrial ones, not because they are less intricate, but because of the physical properties of sea water. These properties control the environment in ways for which there is no comparison in terrestrial communities. Waves, tides, currents, salinities, temperatures, pressures and light intensities for the most part determine the plants and animals that occur and these, in turn, have a major influence on the composition of sediments and the gases in solution.
The marine environment of Gower is greatly affected by the Severn Estuary. The Severn is one of our largest estuaries and because of its classic funnel shape, which is unique in Britain, it has the second highest tidal range in the world. Near Chepstow there is up to 14 metres between high and low tides. The vertical range around Gower is less, varying from about 4 metres on neap tides to over 9 metres on spring tides. To the east of Swansea the Bristol Channel is truly estuarine, the water has a very high silt content, and there is a limited range of plants and animals on the shore. Westwards though, around the peninsula, the water is highly saline and the intertidal fauna and flora is much more varied. Even so the shores still lack a proportion of the species that might be expected, partly because of occasional low surface salinities, but to a large extent because of the persistent high turbidity created by the large rise and fall of the tides. Such a high level of suspended sediment also reduces light penetration and the cloudy, silt-laden waters of the Bristol Channel therefore have a major influence on the types of communities present on the seabed.
There are many more species present in the waters around Gower than most people realise. Sharks, turtles, seals, porpoises, dolphins and even some of the larger whales have all been seen in the area and are an important part of this rich resource.
The features of Carboniferous Limestone shores are that they are very porous, eroded and pitted. The upper shore in Gower therefore tends to be very irregular, ridged, and fissured, becoming smoother lower down; extensive limestone platforms, once known as ‘huvvers and scarras’, are a characteristic of many sections of the coast (Fig. 57). Vaughan-Thomas (1983) mentions that ‘This shelf is surprisingly wide in places – on Port-Eynon Point, for example, in Overton Mere and around Worms Head. I cannot think of any other section of the Welsh coast with quite the same type of feature.’ The Intertidal Survey Unit of the former Nature Conservancy Council visited several stretches of the shore during the late 1970s and considered the area to be of primary biological importance, and more recently the Countryside Council for Wales has carried out a comprehensive study of the intertidal area.
FIG 57. The extensive limestone platforms, known as ‘huvvers and scarras’, near Paviland. (Harold Grenfell)
the author for Figures
The key species of rocky shores have a vertical zonation, which produces a distinctive banded appearance at low tide. A zone of lichens, a white barnacle zone and a zone of brown seaweeds dominate the upper, middle and lower shore levels respectively. The brown seaweeds are also separated, the channelled wrack Pelvetia canaliculata being highest on the shore, followed by the spiral wrack Fucus spiralis, and then the bladder wrack Fucus vesiculosus. The serrated wrack Fucus serratus is typical of the lower shore, while the lowest level of all is usually occupied by the oarweed Laminaria digitata. This pattern partly reflects the different degrees of tolerance to desiccation and submergence shown by the various species. The number of marine invertebrate species increases down the beach and barnacles and marine snails including periwinkles, top shells, dog-whelks and limpets are typical of the mid-shore. On the lower shore, these are joined by species less tolerant of desiccation such as sponges and sea firs. Various coastal birds feed on rocky shores at low tide and at high tide their place is taken by coastal fish.
The upper shore, which is only covered during high spring tides, is dominated by extensive bands of orange, grey and black lichens on the bedrock, with the orange lichen Caloplaca marina lying above a band of black tar lichen Verrucaria maura and associated species such as V. amphibia (Fig. 58). Marine animals characteristic of this zone, which hide in cracks and graze on the rocks, include the periwinkles Melarhaphe neritoides and Littorina saxatilis. A speciality of the Glamorgan coast is the small white woodlouse Metatrichoniscoides celticus, which lives beneath deeply embedded stones just above the high tide mark. Although naturally overlooked to some extent it does appear to be quite rare and most of the records are from the Gower cliffs. A few terrestrial insect species have also adapted to occupy air pockets in rock crevices in the intertidal zone and the Gower shores contain the very small (2.5 millimetres long) reddish-yellow ground beetle Aepus robini.
Below the lichen zone the majority of the shore is encrusted with the acorn barnacles Chthamalus stellatus and C. montagui, together with limpets. These grade into a lower zone dominated by the barnacle Semibalanus balanoides. In both of these zones there may be extensive common blue mussel beds within crevices and in areas between the bedrock. Lower down the shore mussels become even more dominant and can cover whole platforms. There are areas free of mussels, however, and in these serrated wrack occurs together with an understorey of red seaweeds. The species found in this understorey vary depending on the distance from low water and whether sand is present on the lower shore. High on the shore pepper dulse Osmundea pinnatifida occurs along with carragheen Mastocarpus stellatus, which has been used from about 1830 in herbal medicine as a treatment for lung complaints. Towards the lower shore more sand-tolerant red seaweeds can be found such as the red rose grass weed Rhodothamniella floridula, which forms distinct mats. Small hummocks of grass weed may also contain other smaller red and brown algae and species of worm and amphipod may burrow into the mat. Where sand scour is more severe, it may be rare or absent and ephemeral green seaweeds such as grasskelp Enteromorpha spp. and laver Porphyra umbilicalis dominate the substratum.
FIG 58. Typically pitted and eroded limestone cliffs, with extensive areas of black tar lichen, at Mewslade. (Jonathan Mullard)
Laver, which is still collected locally to make laver bread, can be found throughout the intertidal area. Charles Frederick Cliffe in The Book of South Wales (1850) records in a footnote that ‘seaweed bread or Laver cake if not one of the delicacies is one of the edible curiosities of the Gower Coast. In Gower and Swansea seaweed is rather a popular article of food, women attend Swansea market with baskets of laver cakes, which are sold at 1d. or 2d. each. It is got close to low-watermark, washed well in sea water to free it from sand, then boiled 12 hours and seasoned with salt.’
On the vertical sides of rock platforms there are communities of sponges, sea squirts, red algae and bryozoans (moss animals). In some locations the platforms can be almost completely covered by sponges such as breadcrumb sponge Halichondria panicea (Fig. 59), boring sponge Cliona celata and Hymeniacidon perleve. In the shaded areas of overhangs there tend to be more red algae such as Ceramium virgatum, a small red seaweed growing up to 30 centimetres tall, often on the stipes and fronds of larger seaweeds.
Particularly characteristic of the lower shore are the limestone boring species including the small anemone Fagesia carnea and the sponge Cliona celata, which appears above the rock surface as small yellow spots. The area also attracts large numbers of the common starfish Asterias rubens (Fig. 60), which often has the amphipod Pariambus typicus clinging to its upper surface; this was first recorded in Britain on the Gower coast. Under the rock overhangs at extreme low water a variety of sponges occur, including the purse sponge Grantia compressa and the syconoid sponge Sycon ciliatum. The latter prefers more sheltered conditions than the purse sponge, but both are seen in the greatest numbers during the autumn. Stunted white growths of deadman’s fingers Alcyonium digitatum are quite frequent under these overhangs, together with various sea squirts upon which the spotted cowrie Trivia monacha feeds. Other species that occur on the lower shore include the isopods Dynamene bidentata and Gnathia maxillaris. In drier crevices around the mid-tide level these are replaced by a sea slater Sphaeroma serratum, which is particularly abundant on the Worms Head causeway.
FIG 59. Breadcrumb sponge, a common species in the intertidal zone. (Margaret Hodge)
Often associated with the sea firs and bryozoans on rock surfaces and seaweeds are the sea spiders. Twelve of the eighteen or so British species have been recorded on the Gower shores. The most frequently found species are Nymphon gracile, Nymphon rubrum, Endeis spinosus, Achelia echinata and Achelia longipes, with the first two being the most abundant. Nymphon gracile occurs highest on the shore in the spring and summer, being found particularly on the hydroid Dynamena pumila that grows abundantly on serrated wrack, while Achelia echinata occurs in very sheltered, detritus-covered situations on the sea mat Crisia eburnea.
Although it grows on the lowest part of the shore, oarweed was cut traditionally on the south Gower coast and used as manure for the fields. ‘A common of Oar growing in the sea’ was recorded in 1673 at Bishopston, so it seems that its cutting and carting was carefully regulated. Similarly the Rector of Port-Eynon noted in 1801: ‘Seaweed in great plenty, which is used for wheat and barley.’ Oarweed was in fact cut almost to within living memory. At spring tides the shore bug Aepophilus bonnairei can also be found in this zone. It is a typical land-based bug with long antennae, but it actually lives below sea level, in little cracks in the rock where there are air pockets. This is the only time the bug is actually found on the land and it appears at the extreme low water mark and wanders around in the oarweed. It scavenges for animal material, such as dead or dying copepods.
FIG 60. Common starfish, which frequently has the amphipod Pariambus typicus on its upper surface. The first British record of this latter species was from Gower. (Margaret Hodge)
West Glamorgan Archive Service for Figures
On some sections of the coast, such as that between Port-Eynon and Oxwich Point, there are extensive rock pools. The smaller shallower pools support large areas of the common coralline seaweed Corrallina officinalis and other algae such as the brown seaweed Dictyota dichotoma and the red seaweed Gelidium latifolium. In contrast, large and deep pools are dominated by Ceramium rubrum, a very common red seaweed, on the middle shore, and by sea oak Halidrys siliquosa on the upper shore. These pools are also the home of amphipods such as Gammarellus homari, Apherusa jurinei and Nototropis swammerdami. Pools on the lower shore contain the prawns Hippolyte varians, Thoralus cranchi and the common prawn Palaemon serratus. In the middle shore pools the latter overlaps with the closely related Palaemon elegans, which is the only prawn found in the highest pools. Unlike P. serratus, which migrates offshore in winter, this species remains on the shore all year. At the top of the shore within the lichen zone pools may also support green algae such as Enteromorpha spp. and sea lettuce Ulva lactuca. All of the pools contain areas of sponges.
The shallow pools on the tidal causeway that links Worms Head with the mainland contain a variety of sea anemones, while in the deeper ones there is an astonishing range of unusual seaweeds and even seasonal specialities, such as octopus Octopus vulgaris and spider crabs. A particularly noteworthy resident is the tiny brooding cushion-starfish Asterina phylactica, only 1.5 centimetres across, that is otherwise only known from a very few localities in Pembrokeshire and north Cornwall. There is a star-like pattern of darker brown or green pigment along the centre of the arms and paler areas between the arms. As this species was only recognised recently, little is known about it.
The commonest fish in the pools are the blennies, particularly the shanny Lipophrys pholis, which emerges at high tide to forage over the shore. An adaptable species, it is also often found around artificial structures such as piers. The rare Montagu’s blenny Coryphoblenniuus galerita can also be found on occasions. Common lobsters Homarus gammarus again occur in many of the pools, while sheltering under boulders low on the shore are most of the common British crabs. There is a great tradition of ‘crabbing’ in Gower, recorded eloquently by Vaughan-Thomas, but although some still goes on today it is not as it was. ‘For the old crabbers respected skill and kept bright the names of the great men and women of the past, like Billy Hopkins of Port-Eynon, who had the reputation of going crabbing by moonlight, and Kitty “Crabs” of Oxwich … They knew every hole, almost by name, some of them with strange histories.’ The long spur of rocks beyond the Shipway, near Worms Head, for example, is known as the Crabart. Crabbers used a ‘crabbing hook’, a small hook at the end of a pole, to persuade the crabs and lobsters to leave their hiding places under the rocks and in the pools. The best hooks were known as ‘penny-benders’ because an old-fashioned penny coin could fit exactly inside the curving point of the hook.
The main underwater features of the Gower coast are a series of limestone ridges and gullies between Mumbles and Pwlldu Head with rich seaweed and animal turf, sand-inundated seaweed communities in the shallow water of Oxwich Bay, the wreck of the Strombus and other wrecks in Oxwich Bay, the mussel-dominated seabed between Port-Eynon and Worms Head, and the sandy sediments of Carmarthen Bay. Offshore the Helwick Bank, a long, shallow subtidal sandbank, is unusual in being very exposed to wave and tidal action. The only published studies relating to the subtidal area to date are those carried out by the Field Studies Council (Hiscock, 1979), when 21 sites were dived between Worms Head and Mumbles Head, and a 1995 survey carried out as part of the Seasearch Project, which involves volunteer divers recording information about the seabed and associated marine life (Bunker & Hart, 2002). There have been other limited studies of Carmarthen Bay and a fuller survey of the area was carried out in 1998 as part of a South West Wales Survey. This study will be published as part of the National Museum of Wales BIOMÔR reports series (Mackie, 2003). It did, however, confirm that areas of sediments in relatively shallow waters within Carmarthen Bay support a range of species including bivalves, amphipods and worms, many of which spend their time wholly or partly buried in the sediment. Both Carmarthen Bay and Helwick Bank provide a rich food source for birds and fish.
In the centre of the Bristol Channel south of Gower, extensive areas of the seabed are only covered with a thin layer of gravel, and to the east bedrock is exposed on the seabed. Subtidal bedrock does not extend more than a few hundred metres offshore except at East Helwick, where bedrock slopes away into deep water. The deeper-water rock communities off East Helwick have not been studied in any detail.
The coast to the west of Mumbles Head and around Pwlldu Head is exposed to both wave action and tidal streams. A shallow forest of northern kelp Laminaria hyperborea leads to low-lying bedrock with a rich mixed turf of red seaweeds and animals, including sponges. These red seaweeds include flat tentacle weed Calliblepharis ciliata, iridescent ruffle weed Cryptopleura ramosa, cock’s comb Plocamium cartilagineum, Irish moss Chondrus crispus and dulse Palmaria palmata. Due to the silty conditions seaweeds do not grow very deep. The northern kelp for instance extends only down to 1 metre below chart datum, compared with around 10 metres in west Pembrokeshire. Below this a turf of red seaweeds descends to 3 or 4 metres below chart datum and lower down animals dominate the communities. The water, however, is rich in food and some species, such as the common blue mussel and the subtidal reef sandworm Sabellaria spinulosa, thrive in these conditions.
The common names of sponges and sea squirts are usually fairly descriptive, being often named by divers rather than biologists, and animals present amongst the red seaweed turf include guarded flask sponge Scypha ciliata, golf ball sponge Tethya aurantium, white spiky sponge Dysidea fragilis, white hedgehog sponge Polymastia mamillaris and orange wisp sponge Esperiopsis fucorum. Sea squirts recorded from the area include the star sea squirt Botryllus schlosseri, light bulb sea squirt Clavelina lepadiformis (Fig. 61) and orange spot club sea squirt Palladium punctum.
There are a number of gullies, which provide a multiplicity of habitats for marine organisms. The gully sides are dominated by animals, including sponges, sea firs such as Nemertesia antennina, small colonies of deadman’s fingers and dahlia anemones Urticina felina (Fig. 62). Sea squirts are again numerous and include the star sea squirt, light bulb sea squirt and the no spot sea squirt Morchellium argus. The bottoms of the gullies are colonised by species tolerant of the scouring effect of the tides such as jelly fingers Alcyonium diaphanum and horn wrack Flustra foliacea. The crevices and overhangs also provide shelter for the edible crab Cancer pagurus, velvet swimming crab Liocarcinus puber, common lobster and spiny spider crab Maia squinado. A common fish familiar to divers, the tompot blenny Parablennius gattorugine, also occurs in this area. It is a medium-sized fish that feeds on small invertebrates, including sea anemones.
FIG 61. Tubeworms and light bulb sea squirts, one of many sea squirts recorded from the area. (Paul Kay)
FIG 62. Dahlia anemone, one of the most colourful species found offshore. (Paul Kay)
West Glamorgan Archive Service for Figures
In contrast to the rest of the coastline, Oxwich Bay provides a degree of shelter from wave action and tidal streams. The bay is only about 10 metres deep and the seabed is mainly sandy. Inshore, shallow bedrock is occupied by sand-tolerant seaweeds and mossy clumps of red rose grass weed occur together with larger species including little forked worm weed Furcellaria lumbricalis, slender red filament weed Gracilaria gracilis and red bottlebrush weed Halurus equisetifolius. Animals include common lobster and common shore crab Carcinus maenas. Conspicuous species in the shallow sandy areas include sand mason worms Lanice conchilega, razor shells and hermit crabs. Patches of mussels are widespread, as is the white horseshoe worm Phoronis hippocrepia and various sea squirts.
The Strombus and other wrecks in Oxwich Bay provide substrates raised above the generally low-lying and sediment-covered rock on the seabed and therefore support species that are not found elsewhere along the coast, or which are uncommon in other locations. These include the spiny antler sponge Raspailia hispida, white hedgehog sponge and plumose anemone Metridium senile. The Strombus, in particular, is the only known Gower locality for Devonshire cup coral Caryophyllia smithii and is also frequented by large conger eels Conger conger and by ocean triggerfish Balistes balistes. The ocean triggerfish was once a rare summer visitor to the area, but now breeds in the Bristol Channel, probably as a result of the warmer temperatures. The upper surfaces of this wreck, which lies in shallow water to the south of Oxwich Bay, are covered in foliose seaweed, including equally divided net weed Dictyota dichotoma. Conspicuous animals on the wreck include spike barnacle Balanus crenatus, rosy feather-star, candy-striped flatworm Prostheceraeus vittatus and bird’s head coralline Bugula turbinata.
To the west of Oxwich Bay, between Port-Eynon and Worms Head, the coast is again more exposed. Much of the bedrock on this section has a dense covering of common blue mussels, which provide food for the common starfish. Large mussels tend to be found only in depths shallower than 3 metres; below this depth the beds are full of small individuals. Although mussels far outnumber any other species in terms of numbers and biomass the area is very species-rich, with many other organisms present in low numbers. The richness of the fauna associated with mussel beds in intertidal areas is well documented and the same seems to be true on the subtidal rock. Mussel beds are in fact among the most productive habitats on earth, often rivalling the productivity of tropical rainforests and kelp beds, due to their complex three-dimensional structure. They can often reach a considerable thickness and both the living and dead mussel shells increase the surface available for colonisation.
Mobile organisms move freely through the complex matrix of shells and interconnecting byssus threads, by which mussels attach themselves to hard surfaces. These species include common lobsters, bib Trisopterus luscus, ballan wrasse Labrus bergylta, pollack Pollachius pollachius, an anglerfish Lophias piscatorius, the uncommon ghost sea slug Okenia adspersa and the orange and black spotted sea slug Thecacera pennigera. There are large numbers of the latter at Mumbles and it is thought to be an introduced species that has developed a self-sustaining population.
At the time of the 1978 survey large populations of common starfish were present on the mussel beds, and at some sites there was a distinct line of densely packed animals working its way across the bed, leaving dead mussel shells behind. Where the mussels have been removed, by starfish or other agencies, blue-mouthed red sea squirts Polycarpa scuba occur along with a range of other species including Taonia atomaria, Obelia dichotoma and Sertularia argentea. Anemones include the cave-dwelling anemone Sagartia troglodytes. The anemone uses its tentacles to prey upon small shrimps and crabs. In turn it is preyed upon by the grey sea slug Aeolidia papillosa and the tompot blenny. Colour is not a good method of identifying sea anemones, and this is especially the case with Sagartia, which is more variable in colour than any other British sea anemone. There are two forms, a large form (decorata), which is typically up to 50 millimetres across the base and 100 millimetres tall, and a small variety (ornata) that is frequent amongst rocks or mussels; this form is usually green or brown and rarely exceeds 15 millimetres across its base.
Like the common blue mussel, another bivalve mollusc, the native or flat oyster Ostrea edulis, also has a typical range of species associated with it. The polychaete worm Polydora ciliata burrows into the shell, weakening it and increasing the oyster’s vulnerability to predation and physical damage, whereas the related Polydora hoplura causes shell blisters. Boring sponges Cliona spp. may also weaken oyster shells by boring into them, especially in older specimens
One of the earliest records of the oyster at Mumbles relates that Oystermouth villagers used to eat them on a regular basis and that children were fed oysters from a very early age as a cheap and easily obtainable supplement. The oyster beds were worked for their own needs until the early 1800s, when the skills of the villagers were improving and the size of the settlement was growing. More boats were being used and their catch was increasing as people had begun to recognise the potential demand for oysters. By 1830 the oysters were being sold along the South Wales coastline and were transported as far as Bristol. Transporting oysters over these distances required temporary storage and the oyster fishermen overcame the problem by building shallow holding pens called ‘perches’ in the intertidal shallows where they could hold a week’s catch alive, in natural conditions, until an order could be met. Good examples of these can still be seen on the beach in front of the Salthouse at Port-Eynon. Each man’s perch was safe from theft, protected by an unwritten agreement among the villagers. The fishing period ran from the beginning of September until the end of April. The oyster spawning months ran from May until August and the fishermen would rigidly adhere to this rest period. As in most fisheries, however, as trade increased larger boats were used, and the small rowing boats were replaced by larger sailing boats in the mid nineteenth century. The new boats increased the yield substantially and the industry appeared indestructible. In the 20 years between 1850 and 1870 Swansea and Gower experienced an oyster boom. The boats in Swansea alone were bringing in around 4,000 oysters per boat per day and the fishermen were making a lot of money. In 1871 when the trade peaked 10 million oysters were landed, fetching £50,000, and there were 600 men employed in the trade.
The quality of the oyster, the amount of money being made and the huge increase in demand as the fame of the shellfish spread began to cause problems. Boats arrived from London, Bristol and Liverpool and too many fishermen flooding what had been a very lucrative market began to cause a small, but steady, decline in the prices. By 1886 the trade had reached its lowest ebb with prices hitting rock bottom, to the point where the fishermen were struggling to make a living. By 1890 the few fishermen still operating were bringing in catches of only 200 oysters. The fishery continued at this level until, in 1920 and 1921, the flagellate protozoan Heximata spp. infected the oyster beds, causing mass deaths. Many populations did not recover and this effectively ended the industry, although one or two boats persevered until 1930, more as a pastime than for employment. Although the oyster beds still exist they remain depleted. Recovery of the populations is dependent on larval recruitment since the adults are permanently attached and incapable of migration. This is sporadic, depending on local environmental conditions and the presence of suitable substrates, especially adult shells or shell debris. At present it seems that the oyster beds will never improve significantly.
A recent survey of the two remaining oyster beds in Wales found oysters in many sites in the Milford Haven waterway in Pembrokeshire and none in Swansea Bay. Despite this result there are oysters present, but they are in low numbers, making them harder to find. Over-fishing, pollution and poor reproduction has brought about a devastating decline in the population.
Marine, or littoral, caves form special environments within rocky shores and Britain has the most varied and extensive sea caves on the Atlantic coast of Europe. The communities present in caves vary considerably depending on the structure and extent of the cave system, the degree to which they are submerged and the exposure to scour, turbidity and surge, and their geology. Although the walls and roof are constructed of hard rock, the floor of the cave can either be soft or hard. Caves on the shore and in the shallow sublittoral zone are continually subject to wave action and therefore tend to have floors of coarse sediment and boulders that move and scour the inside of the cave. In Gower there is a high sand table and much of the inside of the marine caves, such as Bob’s Cave under Mumbles Head (Fig. 63), tends to be worn by sand and therefore inhospitable to animals and plants. Where there is less sand, caves are typically colonised by encrusting animal species, and often support shade-tolerant seaweeds in the ‘twilight zone’ near their entrances. The caves themselves vary in size, from only a few metres in depth to more extensive systems, which may extend a considerable distance into the rock. While the Countryside Council for Wales has carried out several surveys of sea caves along the North Wales shoreline there has yet been no similar survey of the Gower coast and it is quite likely that a number of small, but species-rich, caves will be discovered by divers.
Caves in deeper water are subject to fewer disturbances and may have silt on the floor. The sponges Dercitus bucklandi and Thymosia guernei, solitary ascidians, bryozoans and the sessile larvae of jellyfish are characteristic of these deeper caves. Small deep caves also provide shelter for crabs and lobsters.
FIG 63. Bob’s Cave under Mumbles Head, a large sea cave scoured by sand. (Margaret Hodge)
Barry Stewart for Figures
The Helwick Bank, a linear sandbank aligned east-west, lies to the west of Port-Eynon Point, about 4 kilometres south of Worms Head. The Reverend J. D. Davies in his history of West Gower (1894) noted that ‘At low water during extraordinary spring tides, I have been told that pilots have been known to jump from a boat on these sands and that these have been seen almost dry.’ He goes on to record an ancient tradition with respect to the ‘Helwicks’, ‘that there was once a road along these sands and that pieces of iron horse’s shoes have been dredged up’. Davies also notes that ‘Hele is an old Anglo Saxon word still in use and means to cover something up: to “hely potatoes” is a very common expression in Gower, also “to hely up the head”, i.e. to cover it up with a whittle (a woollen shawl) or handkerchief.’
Subtidal sandbanks such as Helwick Bank are the result of relatively high energy conditions. As such they will be naturally disturbed by large changes in sea state, caused for example by storms. The animal communities found in and on Helwick Bank reflect the exposed conditions, being generally tolerant of high levels of disturbance. The first biological sampling of the Helwick Bank occurred during the late 1970s (Tyler & Shackley, 1980). This study was an investigation of the biology of the linear sandbanks on the north coast of the Bristol Channel and was not a specific study of the Bank, although samples were taken from it. It was not, however, a survey of an undisturbed environment, but represented a study of an area which at that stage had already been subjected to between 20 and 30 years of aggregate extraction. Unfortunately there are no biological data for the Helwick Bank and the adjacent seabed before dredging began. A very limited field survey was carried out in 2000, as part of the monitoring of dredging operations, to identify seabed habitats and the types and numbers of animals present. In 2001 a new joint survey involving the Countryside Council for Wales, the National Museum of Wales and the University of Wales at Bangor provided the first quantitative data on the invertebrate life associated with Welsh sandbanks, including Helwick Bank (Darbyshire et al., 2002). Although the 2001 survey found that the range of invertebrates in the sandbanks was generally lower than that of the coarser sediments nearby, the animals associated with the sandbanks often formed distinct groupings.
The seabed sediments of the Helwick Bank area are uniform, medium-grained sands with little or no fine or organic material. Sand-waves are present along its flanks, indicating that sand transport is occurring. To the south an area of megaripples (large ripples of sand on the seabed surface) merges to the west with an area of sand-waves and gravelly sand. Extensive research over the past 30 years has shown that the predominant sand transport pathway under the normal tidal regime south of the Gower coastline is towards the west. At the eastern end there is a link with the Port-Eynon subtidal area. Under particular weather conditions, for example during southwesterly storms, sediment will travel into the embayment, and into Port-Eynon Bay. Normally, however, sediment will tend to move out from the bay towards the south and west.
The shallow sandy sediments are colonised by a burrowing fauna of worms, crustaceans, bivalve molluscs and echinoderms. Mobile animals at the surface of the sandbank include shrimps, gastropod molluscs, crabs and fish. Sandbanks such as Helwick are also important nursery areas for fish such as sand eels Ammodytes spp., which are an important component of marine food webs. They prey on the eggs and larvae of other fish and crustaceans and themselves form a significant part of the diet of many of the commercially important fish species harvested in and around the Helwick Bank, including sea bass Dicentrachus labrax, and a number of species of flatfish. They also provide food for a number of seabirds and the Bank is therefore a key feeding ground for species such as puffins Fratercula arctica and razorbills and especially common scoter Melanitta nigra.
Studies have shown that large numbers of molluscs, echinoderms and crustaceans can be killed or damaged by dredging operations, together with extremely large numbers of the burrowing sand eel. The long-term impact of the dredging operations is difficult to determine, however. In 1996 a local dredging company applied for permission to extract 200,000 tonnes per year from the Helwick Bank for a ten-year period. This application represented both a continuation of existing practices and an increase in the sand that might be removed. A five-year licence was granted in 1998 to extract 150,000 tonnes per annum and in 2003 the company was granted a two-year extension to their licence. The extension permits the company to extract up to 214,000 tonnes of sand at no more than 107,000 tonnes in a year. There is intense local concern that the dredging might interrupt the movement and exchange of sediment between the shoreline and the seabed and that the dredging might reduce the protection given to the shore by the Helwick Bank.
Within Carmarthen Bay there are also several other smaller sandbanks in relatively shallow waters that support a range of species (including bivalves, amphipods and worms), many of which spend most of their time wholly or partly buried in the sediment. The Mixen Sands stretch westward from Mumbles Head and are marked by a bell buoy, but there are no records of the species that may be found there. In stormy weather, as with the Helwick, the sea can be seen breaking over the sandbank.
Carmarthen Bay contains a complex of unusually diverse marine habitats and associated species, including habitats important for migratory fish and migratory and wintering bird species. There is a wide range of seabed types, including mud, sand and rock, although fine sand characterises the majority of the seabed from Caldey Island in the west to Worms Head in the east. The bay, with its adjacent estuaries, sandbanks and extensive salt marshes, is one of the most varied stretches of coastline in the UK. It is designated as a Special Area of Conservation under the EC Habitats & Species Directive, and is a Special Protection Area under the EC Directive on the Conservation of Wild Birds, mainly because of the numbers of common scoter that occur here. In Britain this diving duck is considered a nationally threatened species because of its small and declining breeding population. Despite an estimated 20,000 individuals overwintering in Carmarthen Bay, by far the most significant British site for this species, there are only 200 pairs breeding in Britain and Ireland. The scoter is unusual among ducks in that the male is almost black, with only an orange-yellow patch on its bill. The female is dark brown with pale cheeks.
The bay encloses a wide range of rich and diverse marine habitats, species abundance and richness being strongly influenced by the prevailing wave and tidal regimes, with the eastern side of the bay, particularly Rhossili Bay, being open to the full force of the prevailing southwesterly swell. Two very similar animal communities have been identified in the bay, the first corresponding to areas where there are stronger tidal flows, increasing wave height and correspondingly coarser, cleaner sediments with a generally low species diversity, and a second community with a high species diversity which is dominated by deposit feeders. This second community can be divided again due to differences in abundance and diversity into two groups, one related to areas containing fine material and mud and one related to areas of clean fine sand.
The larger fauna of the seabed typically consists of the deposit-feeding polychaete worms Spiophanes bombyx, Magelona spp. and Spio spp., the amphipods Perioculodes longimanus, Pontocrates arenarius and Bathyporeia spp. and the bivalves Mysella bidentata, Chamelea gallina and Fabulina fabula. The latter species is an important food item for the common scoter. In areas of stronger tidal flows, increasing wave height and correspondingly coarser and cleaner sediments, such as off Rhossili, sedentary animals like the thin-shelled Fabulina fabula and the fragile tube-dwelling polychaete Spiophanes bombyx are much reduced and instead Nereis cirrosa and the cumacean Pseudocuma longicornis are present. The cumacean, a minute bottom-living, somewhat scorpion-like crustacean, is an active burrower in the upper few centimetres of sediment and is also highly mobile, making it well adapted to a constantly changing sand habitat The burrowing crab or masked crab Corystes cassivelaunus is also a conspicuous species in this habitat, being adapted to the same conditions; it can also be found along the beaches (Fig. 64).
The brittlestars Ophiura ophiura and Amphiura brachiata occur in large numbers in the bay together with the large starfish Asterias rubens and Astropecten irregularis. Molluscs include the small opisthobranch Philine aperta, the common whelk Buccinium undatum and the dog-whelk. Cuttlefish Sepia officinalis are also present. Cuttlefish have an interior shell that is called a cuttlebone, and these are frequently washed ashore onto the Gower beaches. They are chambered and filled with gas that acts as a buoyancy control.
Despite the protected status of Carmarthen Bay, its seabed communities are currently under serious threat from the development of an unsustainable fishery. Local and international fishing-industry interests are eager to deploy hydraulic fishing gear to harvest razor shells for sale overseas. The hydraulic blade dredge is generally regarded by marine ecologists as one of the most destructive fishing methods, because of the harm it causes to soft-sediment areas. It operates by directing water jets into the seabed in order to liquefy the sediment; suspending the shellfish in a slurry that is then sieved by the mesh of the dredge. Hydraulic dredges are an efficient method of harvesting shellfish, but have been found to seriously disturb benthic invertebrates and redistribute the sediment habitat. Unfortunately the area is not alone in being threatened by expanding shellfish fisheries; a similar situation exists in St Brides Bay, Pembrokeshire.
FIG 64. The burrowing or masked crab, a common animal of the sandy seafloor and beaches. (Margaret Hodge)
All these operations are licensed by the South Wales Sea Fisheries Committee, under whose jurisdiction these areas of seabed fall, but local naturalists are seriously concerned that the fishing interests are being given precedence over conservation issues, and legal action is currently being proposed at a European level to stop the dredging.
Fish species recorded from Carmarthen Bay include solenette Buglossidium luteum, sole Solea solea, plaice Pleuronectes platessa and dab Limanda limanda. Some of these were recorded by Isaac Hamon, who noted that ‘along this coast there are these sort of fish taken or to be taken (viz) Salmon, hering, suen, cod, mackrell, plais, millet, sole, flooke, flawnders, Thornback, Skate, Whiting, Turbut, hawk, Conggereeles, bowman, bream.’ Some 300 years later inshore fisheries are still well established in the area, with boats launching mainly from Burry Port, Swansea and Oxwich Bay. A number of angling boats also operate commercially under charter, catching species such as the tub gurnard Trigla lucerna (Fig. 65). This is the largest of the gurnards found around Gower, reaching a maximum length of 0.75 metres, although most individuals are between 0.5 and 0.6 metres. Like all gurnards it has a large head covered by protective bony plates, and the lower three rays of the pectoral fin are separate and fleshy. It is usually found on mud or sandy seabeds, feeding on small fish such as sand eels, gobies and dragonets Callionymus lyra, and on crabs and shrimps. They will also feed high in the water when there are plenty of small fish about and can sometimes be seen breaking the surface. The Welsh record rod-caught tub gurnard was caught from the shore at Langland Bay and weighed nearly 5 kilograms. Potting for lobsters, edible crabs and velvet swimming crabs takes place in the rocky areas inshore while offshore there is trawling for plaice, sole, whiting Merlangius merlangus and cod Gadus morhua. Tangle nets are used to catch rays and turbot Psetta maxima. Netting for bass takes place with both fixed and drift netting and there is bottom-set netting in winter using small-mesh nets to catch sole, whiting and cod.
In 2004 a sea sturgeon Acipenser sturio weighing 120 kilograms and nearly 3 metres long was caught in Swansea Bay. One of the largest European fish to breed in rivers, the sea sturgeon has been fished to the brink of extinction and is now a protected species. It should not have been killed and it seems that more information needs to be provided to fishermen about rare species. The elongated body tapers to a narrow pointed tip at the snout and lacks scales, apart from the five rows of whitish bony platelets, or scutes, that run the length of the fish. Sturgeons have no teeth, but feed opportunistically on bottom-dwelling creatures, feeling for prey amongst the mud with the sensitive barbels on the chin and then sucking them into the mouth. Their food consists mainly of invertebrates and small fish. Previously abundant along all European coasts, sturgeon are now restricted to a single population that breeds in the Gironde River in France and the species is consequently extremely vulnerable. These long-lived and slow-growing fish have been extensively fished both for their flesh and for the eggs, which are sold as caviar. A captive breeding programme is currently in progress with the long-term goal of reintroducing the fish to some of its former range. After some controversy about its sale by the fisherman who caught it, the sturgeon was sent to the Natural History Museum. The fish was probably more than 100 years old and it will eventually be held as part of the national fish collection.
FIG 65. Tub gurnard, the largest of the gurnards found around Gower. (Paul Kay)
Two years earlier, in July 2002, a fisherman caught a 3.6 metre thresher shark Alopias vulpinus off Gower. Thresher sharks are often present in British waters and can come very close to beaches, and have been seen swimming near Mumbles lighthouse. They will readily approach the shoreline following schools of fish, such as mackerel and herring, and can enter shallow bays or narrow passes between islands. Thresher sharks can often be seen swimming at the surface with their long caudal fin scything the water, whilst actively feeding upon small fish that seem to ‘boil’ ahead of the shark. The elongated tail is used as a specialised feeding tool, the shark first herding and then stunning fish with strong sweeping blows. Infrequently they will also eat crustaceans and even seabirds. Overfishing is threatening the thresher shark and populations are said to ‘have collapsed’ – in other words, they are close to commercial extinction. Even ‘recreational’ fishing of this species therefore needs to be discouraged.
Other sharks recorded from the area include mako shark Isurus oxyrinchus, porbeagle shark Lamna nasus and basking shark Cetorhinus maximus, which feeds on plankton. Basking sharks are migratory and occur near the coast during the summer. There were sightings off Gower during the late 1970s and a probable sighting by a water-skier off Oxwich in 1984. There is an interesting historical record by Dillwyn of a great hammerhead shark Sphyrna mokarran that was caught in Carmarthen Bay in 1839. Its stuffed skin was later sold for £28 as a sideshow curiosity. Dillwyn wrote to Henry de la Beche saying he had tried, but failed, to procure the fish. This species is a very rare vagrant from tropical waters and only five were recorded from British waters throughout the twentieth century. The strange shape of the head, from which the species gets its name, is thought to make the shark more sensitive to electrical signals, which they use to detect hidden prey; common stingray Dasyatis pastinaca being a favourite food.
Sharks, rays and the related skates are distinguished from bony fish by their cartilaginous skeletons. Species with long snouts are usually known as skates, while those with shorter snouts are called rays. A hundred years ago British waters were packed with both skates and rays, including the common or blue skate Dipturus batis, which can reach 3 metres in length. Today most species are in decline and the blue skate is now listed as endangered. Their current status around the Welsh coast is unclear, although there is evidence that the most common, the thornback ray Raja clavata, has declined in recent decades. The Welsh Skate and Ray Group and the Shark Trust are therefore collecting information on past and present catches to improve knowledge of the distribution and population trends of these important fish. Skates and rays have commercial, angling and conservation value and the South Wales Sea Fisheries Committee, like some other Sea Fisheries Committees, has set a minimum catch size under a bye-law. Although this is not the most popular method, it is hoped that the current bye-law will be replaced in due course, either by a new bye-law or by European legislation covering the twelve-mile (22-kilometre) inshore zone. The decline of most of these species is being used as a clear example of how the Common Fisheries Policy is failing, and to promote the urgent need for a change.
The common stingray is still, however, found inshore in reasonable numbers during the summer and must always be handled with great care, as there are venom sacs connected to spines along the slender whip-like tail, and a wound inflicted by these spines can be extremely painful. Electric rays Torpedo nobiliana have also been caught in Carmarthen Bay. These rays have rounded disc-like bodies and smooth skin and two dorsal fins located on a short, thick tail. The upper surface of the ray is dark greyish-blue to dark brown and the underside is white. The species can grow up to 2 metres long. The electric ray catches bottom-living fish in its pectoral fins and produces a powerful electric shock from specialised organs located in the pectoral fins, which stuns or kills the fish before it is eaten. As a result it was known locally as a ‘numb fish’, and Dillwyn records that:
One of these men (fishermen), who called it a Numb Fish, told me he has known it to lie quite concealed in the mud, both in the weirs and in the sea, at low water, and that the shock creates a great surprise when it is accidentally trod on.
Ever the enquiring naturalist, he acquired a ‘torpedo’ that had been caught alive on the 17 July 1840 and kept it in a saltwater pool he had in his garden, but it soon died. Other rays common in the area include the thornback ray, the painted ray R. microocellata and the spotted ray R. montagui. The spotted ray has a flattened, diamond-shaped body with broad wing-like pectoral fins and a long tail. It is similar in size and shape to the thornback ray, but the latter has characteristic large spines with button-like bases scattered over its back.
As the Bristol Channel is funnel-shaped, faces southwest and has strong tidal currents it tends to act as a trap for species which may be brought to the southwestern approaches by the Gulf Stream and the prevailing wind, such as the Portuguese man-o’-war Physalia physalia and the by-the-wind-sailor Velella velella (Fig. 66). Both are ocean-dwelling species that are often washed up around the Gower coast. In July 2003, for example, numerous specimens of by-the-wind-sailor were stranded along the southern end of Rhossili beach and there was a similar mass stranding, all along the South Wales coast, in September 2004. Like the Portuguese man-o’-war, by-the-wind-sailor is a pelagic colonial hydroid, a complicated colony, some elements of which specialise in feeding, some in attack or defence, some in reproduction and some in movement. The float in this species, which is an oval disc, is deep blue in colour and can be up to 10 centimetres in length. Short tentacles hang down into the water from the float. A thin semicircular fin is set diagonally along the float acting as a sail, which gives the animal both its scientific name (from velum, a sail) and its common name. The colony feeds on pelagic organisms, including young fish, caught by stinging cells on its tentacles. In turn the sea slug Fiona pinnata, violet snail Janthina janthina and sunfish Mola mola prey upon the colony. Dillwyn records that in July 1824 there was a mass stranding of violet snail on Oxwich beach. Over 200 individuals were collected, including a related species, J. exigua. These ‘purple sea snails’ are pelagic molluscs that float on a ‘bubble-raft’.
FIG 66. By-the-wind-sailor, a common pelagic species often found stranded on the beaches. (Margaret Hodge)
Several sightings of large sunfish have been made near Worms Head, and a specimen weighing 18 kilograms was caught in 1983; even larger specimens sometimes occur. One sunfish caught on the surface in Caswell Bay on 28 August 1851 was 1.8 metres long and said to weigh around 500 kilograms. The most recent sighting is from 2002. The fish’s unusual rounded shape is reflected in its scientific name, as Mola is Latin for millstone. In 1843 the rare oblong sunfish M. oblongus was caught in Swansea Bay, but it has not been recorded since.
The large dustbin-lid jellyfish Rhizostoma octopus is sporadic in occurrence from year to year, but when present it occurs in large ‘swarms’ in the summer and autumn. Enormous numbers are often found in Rhossili Bay. Naturalists have struggled for more than half a century to record the distribution and abundance of dustbin-lid jellyfish in British and Irish waters. Today, low-flying aircraft are being used to survey wide areas and this method has revealed huge numbers of these jellyfish (roughly one per square metre) in Carmarthen Bay between April and November. What causes these jellyfish to aggregate in the bay is unknown, but they also occur in similar numbers in Tremadoc Bay, near Criccieth on the Lleyn peninsula. It is generally a species of coastal waters and can be found stranded on the shore, or in rock pools, by receding tides, but it is believed that some specimens probably live in deep water during winter. The animal has a solid appearance and varies in colour from whitish pale or yellow to shades of green, blue, pink or brown. Unlike some jellyfish there are no marginal tentacles and there are four pairs of very large oral arms on its under surface, hence the specific name octopus. The small amphipod crustacean Hyperia galba can be found throughout the body and more usually in its gastric or gonad pouches, where they are sought by some species of fish.
Another jellyfish, the blue jellyfish Cyanea lamarckii, which occurs in astonishing shades of blue and violet and can sting people, has also been found washed up on Gower beaches. It is a pelagic species that occurs in coastal waters all around the British Isles. The colour varies from translucent through pale yellow, pale brown, pale grey to light blue or purple. In faintly coloured specimens the blue tends to outline the pattern of the internal sculpting of the bell, which can grow up to 30 centimetres in diameter. The tentacles, arising from the underneath of the bell, are arranged in eight horseshoe or rectangular-shaped groups each with 40 to 60 tentacles.
Other species frequently recorded include the common jellyfish Aurelia aurita, which is almost certainly the most abundant of them all, and the compass jellyfish Chrysaora hysoscella.
While there is little information about jellyfish around Gower, it is known that they are the staple diet of the critically endangered leatherback turtle Dermochelys coriacea, which has been recorded from the area, together with loggerhead turtle Caretta caretta and Kemp’s ridley turtle Lepidochelys kempii. The leatherback breeds in shallow tropical waters and it is clear that its extensive migrations are the result of following swarms of jellyfish. One of the mysteries of leatherbacks is how they can thrive almost entirely on jellyfish, which are composed for the most part of water. In British waters they occur seasonally and the majority of sightings, usually of adults, are between August and October.
A particularly large specimen was seen off Gower in September 1966 and was described in the newspapers as being ‘the size of a small car with a head as big as a football’. Similarly in September 2003 a large turtle was seen in the Loughor Estuary, swimming at the surface in a westerly direction together with large blooms of dustbin-lid jellyfish. The leatherback is the world’s largest sea turtle and the most widely distributed reptile; it has a shell normally up to 2 metres in length, and can weigh half a tonne. They are spectacular animals, and the largest specimen ever recorded was found stranded at Harlech in 1988. The turtle weighed 916 kilograms and was 2.91 metres long, and can now be seen in the National Museum in Cardiff. The same year a plastron, the underpart of a leatherback shell, was found in Three Cliff Bay, one of a number of occasions when dead animals have been washed up on the Gower beaches (Fig. 67). The leatherback’s characteristic feature, as its name suggests, is a blackish leathery shell with seven longitudinal ridges along the back, three of which are clearly visible when the animal is swimming at the surface. The skin is also black and relatively smooth with pale spots. The black leathery skin, large size, and prominent ridges on the back make them easy to identify. The leatherback is warm-blooded (endothermic), maintaining a body temperature of around 25°C, which is unusual as most reptiles are cold-blooded (ectotherms).
FIG 67. Mark Winder, Head Warden for the National Trust, with the remains of a leatherback turtle found on the Worms Head causeway in 1996. (Paul Llewellyn)
West Glamorgan Archive Service for Figures
Populations of leatherbacks are in serious decline due to a number of factors, but the main threats have been a prolonged harvest of eggs and the incidental capture in oceanic fisheries. The international nature of this problem means that the survival of the species will depend on cross-border collaborations, focused not only on the tropical nesting beaches but also on the more temperate feeding grounds that lie thousands of kilometres away. Despite this, our knowledge of leatherbacks outside the breeding season remains almost nonexistent.
In April 2003 the Irish Sea Leatherback Project was established as a joint initiative between the University of Wales Swansea and University College Cork. Key elements of the project include aerial surveys of the Irish Sea, satellite-tracking leatherbacks from their tropical nesting grounds to identify the routes they follow to get to high latitudes, shoreline jellyfish surveys, schools workshops and public seminars. The project hopes to answer the issue of whether leather-backs are merely oceanic wanderers that find themselves in British waters or whether they form an important part of our natural heritage.
All other turtles seen off Gower are likely to be juvenile or subadult loggerhead and Kemp’s ridley turtles. The loggerhead turtle is another large sea turtle, with a carapace up to a metre in length. It is a carnivorous species, feeding mainly on benthic invertebrates, especially molluscs and crustaceans, using its very bulky jaw muscles to crush their shells. Adult Kemp’s ridleys are normally bottom-feeders, foraging in crab-rich shallow inshore waters. It is critically endangered and the total population of this species is thought to number no more than 900 adult females and an unknown number of males and subadults. The occurrence of these ‘hard-shelled’ species in the Bristol Channel is not a normal part of their life history; they have been blown from warmer waters by unusual weather conditions such as prevailing southwesterly storms. The animals are usually in very poor health, as hard-shelled turtles are not adapted to the cool seas around Britain, but prompt action can save a turtle’s life and the Marine Conservation Society website provides guidance on this.
Grey seals Halichoerus grypus frequently occur around the peninsula. On the Inner Head of the Worm up to 20 animals at a time haul-out on the dropping tide and can easily be seen from the former coastguard lookout station (Fig. 68). They also appear to breed on the Worm, although there are no specific records of this. Sometimes in the winter months one or two individuals can also be found on the shore near Sedgers Bank in Port-Eynon Bay. In contrast common seals Phoca vitulina are very rare in the region.
FIG 68. Grey seal on the shore of Worms Head. (David Painter)
The harbour porpoise Phocoena phocoena is the most widespread and abundant cetacean in Welsh waters. Investigations of tooth ultrastructure and genetic studies indicate that there are possible subpopulations around the British Isles, one of which is based in the Irish Sea and around Wales. Porpoises are common both inshore and offshore although certain coastal features such as headlands and islands regularly attract high concentrations of animals. These habitats are characterised by strong tidal currents and the animals appear to forage in the tide races that form in their vicinity. Because of this the time of their appearance and location can be predicted to some extent by the tidal cycle. The two main areas of porpoise sightings off Gower are in the vicinity of Worms Head and Burry Holms, where strong tidal races occur on the rising tide between the islands and the peninsula. Because of the large tidal range in the Bristol Channel these races typically attain a velocity in the range of 2.8 to 5.5 kilometres per hour (1.5 to 3 knots) at the spring tides. Groups of up to 20 individual porpoises have been recorded at times, but they most often occur in small groups of one to three animals.
Although the porpoise has been identified as a locally important species, surprisingly little is known about this significant social predator and many basic questions, such as the size of the population around Gower and breeding success, remain to be answered. Although they are frequently seen, they are shy and secretive animals and, unlike dolphins, they rarely behave spectacularly or come to boats, and are therefore difficult to study. A practical scheme, the Gower Marine Mammals Project, which began in November 2002, aims to find answers to these questions. Volunteer cetacean watchers have been actively logging harbour porpoise activity in the area since the mid-1990s, but the new initiative involves permanently mooring hydrophones in Carmarthen Bay, off Burry Holms, off Port-Eynon and in Swansea Bay to continuously detect and record the porpoise echolocation calls. Results to date have been encouraging. A better understanding of the requirements of the species is essential if effective conservation measures are to be taken. Bottom-set gill nets cause the deaths of thousands of porpoises every year and in addition high levels of infectious diseases and parasites have been linked with exposure to pollutants such as polychlorinated biphenyls (PCBS) and heavy metals. Increased shipping in coastal waters and declining fishing stocks also threaten this slow-breeding species.
Common bottlenose dolphins Tursiops truncatus were recorded off the peninsula in 2003 and commonly form groups of up to 25 individuals. Like porpoises, in coastal waters the animals often prefer estuaries, headlands or sandbanks, where there is an uneven sea floor and/or strong tidal currents. Locations such as Rhossili, Worms Head and Burry Holms are therefore key seawatching areas for small cetaceans.
At times larger cetaceans, such as sperm whales Physeter catodon, have been recorded. Gabriel Powell, the agent for the Duke of Beaufort, wrote on 12 March 1761 to the Duke’s mother:
I was last night informed that on Friday last a young whale came on shore near Whiteford Point in the Lordship of Lanmadock … it measures 65 feet in length, 17 feet in heighth as it lay on the sands, and 7 feet from eye to eye, and seems to have had a bruise on the head. It is a male fish of the Sperma Ceti kind. The country perceived it sometime before it reached the shore and took it for the wreck of a vessel, so they were prepared to receive it. As soon as the tide left it they attacked it with hatchets, and in about five hours killed it. As it is a Royal Fish it belongs to my Lord Duke as Lord of the Seigniory.
Stranded cetaceans have been described as ‘Fishes Royal’ since 1324, when a statute was passed which gave the Crown qualified rights to cetaceans stranded or caught in the waters of England and Wales. In 1913 these rights were transferred to the Natural History Museum in London and ever since then the museum has been monitoring standings. The National Stranded Whale Recording Scheme is now the centre of a coordinated investigation into the biology and ecology of cetacean populations around the British Isles, and can be accessed via the museum’s website.
As Powell was engaged in a court case he could not go to the scene immediately, but on 26 March he wrote again:
I returned home on Monday, and yesterday went down to see what I could make of the whale, but found about two-thirds of it had been plundered by the country, and the other third lies buried in the sands, and is now so nauseous that no one will work on it.
Powell also enquired at Bristol about the value of whale oil, but could find no one to buy it; meanwhile it seems local people had enjoyed a feast of whale meat. Sperm whales are usually only found in small numbers throughout the deep waters of the North Atlantic. Sightings in British waters are recorded mainly between July and December, but there is increasing evidence that small groups of males remain at high latitudes into the winter, and this is the period when standings have taken place. The March stranding at Llanmadoc would therefore seem to fit this pattern. Whether it is due to the particular tidal flows in this area is not clear, but Llanmadoc seems to be a regular stranding place for cetaceans. The first volume of the Glamorgan County History (Tattersall, 1936) has a photograph of a school of false killer whales that were washed ashore in May 1934 (Fig. 69).
FIG 69. False killer whales washed ashore at Llanmadoc in 1934. (Colin Matheson)
Melvin Grey for Figure
There has been a surprising variety of species stranded on the Gower shores over the years, including a white-sided dolphin Lagenorhynchus acutus which was washed up on Rhossili beach in October 1967. Contemporary records reveal that ‘Attempts were made to return it to the sea, but it finally had to be shot.’ (In Britain the two options employed in the management of stranded cetaceans are euthanasia and reflotation, that is the release of animals after a variable period of treatment on the beach of origin, or close by.) Other species stranded at Rhossili include lesser rorqual Balaenoptera acutorostrata and common dolphin Delphinus delphinus. In addition Risso’s dolphin Grampus griseus has been recorded from Port-Eynon, Sowerby’s whale Mesoplodon bidens at Mumbles, and a bottle-nosed whale Hyperoodon ampullatus turned up in Broughton Bay in 1965.
Located as it is, on the northern shore of the Bristol Channel and close to the main shipping lanes, Gower is constantly at risk from oil pollution. Half of the world’s extracted crude oil is transported at sea by supertanker, and an important mainstay of tonnage at Avonmouth Docks, further up the Bristol Channel, is petroleum, with nearly two million tonnes of related products imported each year. A much greater quantity is transported to the Pembrokeshire refineries. Most of the oil released into the sea by shipping occurs from routine tank cleaning, during which oil is deliberately released. Much of this disperses naturally, and major oil pollution incidents are fortunately rare. To date there have only been two notable events that have seriously affected the marine environment around Gower.
On the afternoon of 12 October 1978 the oil tanker Christos Betas, fully laden with heavy crude oil, went aground to the west of the Pembrokeshire islands and about 111 tonnes of oil was released into the sea. For three weeks oil was washed up at each tide on the Gower beaches and there were a number of oiled birds. Between 21 October and 9 November 485 birds were recovered on the beaches (Fig. 70). Most were completely covered with oil and long dead. Guillemots and razorbills suffered the most, with over 300 birds of these two species recorded.
This incident was completely dwarfed by the events of 15 February 1996 when a supertanker full of oil (light crude this time), the Sea Empress, collided with rocks at the entrance to the Milford Haven waterway. During the next five days an estimated 72,000 tonnes of oil leaked from the ship, making it the third largest spill to have occurred in Britain and among the top 20 worldwide. Early fears that the oil would move north and affect the islands of Skomer, Skokholm and Ramsey were unfounded, but even so significant amounts of oil entered Carmarthen Bay. Extensive slicks were reported and an oil sheen spread rapidly over a wide area. Most of the oil was never recovered, neither from the surface of the water nor from the beaches, and it is thought to have sunk to the bottom of the bay. Over 7,000 seabirds of 29 different species were found dead or dying. Significant numbers of guillemots and razorbills were affected, but it was Carmarthen Bay’s wintering flock of scoters that were most badly hit, with a minimum of 4,000 birds killed. Many corpses were washed ashore on Rhossili and Whiteford beaches. During the following weeks hundreds of thousands of dead and moribund molluscs, crustaceans and echinoderms were washed ashore around the bay, including areas such as Rhossili and the inlet and estuary, which had not been directly affected by heavy oiling. The long-term effects on marine life remain unclear. Bad as incidents such as these are, however, they account for less than 10 per cent of the total input of oil into the sea and there have been few studies on the continuous and low-level oil pollution that must affect the marine environment around the peninsula.
FIG 70. The remains of an oiled gannet on the beach at Mewslade after the Christos Betas oil spill in 1978. (Harold Grenfell)
There are other pressures from commercial fisheries. The hydraulic dredging of razor shells in sensitive marine habitats so close to the peninsula must be questioned, as must the dredging for ‘seed’ mussels to feed the mussel beds of Swansea Bay, which has seen large vessels working the seabed close to the Knave and around Oxwich Point.
