Llanelli Naturalists Newsletter - May 1995 - No 1
Barry Stewart

It has long been known that the Penclacwydd saltmarsh east of the Machynys Peninsula (SS/51-97-) on the north shore of the Burry Inlet has been an excellent feeding and roosting place for significant numbers of birds. Various influences, including climatic change. land "reclamation" and industrial growth have all affected the partly-urbanised north shore of the Burry Inlet and its bird populations. Yet, despite these great changes, regular recording in the last five years has indicated that a minimum of 13,000 waterfowl and waders have annually frequented this area, probably making it the most important estuarine section on the Inlet's north shore. Any further development or associated disturbance could unintentionally affect the ecology of the site and consequently, consideration should be given to the area's wildlife, in planning future usage of the site.

Past developments have already altered the area eg:

• Penrhyngwyn was once a much larger shingle beach than it is today (Davies, 1985) but it has been considerably reduced in size by the dumping of slag from the old Llanelli metalliferous works. Remnants of the original flora and fauna still survive on the small extent of natural shingle. such as the yellow-horned poppy Glaucium flavum a nationally-declining species, which appears in varying numbers from year to year. Several other locally-scarce plants - such as grass-leaved orache Atriplex littoralis knotted clover Trifolium striatum and cut-leaved deadnettle Lamium hybridum - also occur, whilst the gorse scrub supports a colony of nesting linnets and other birds. Penrhyngwyn is also one of the few known British sites for the millipede Thalassisobates littoralis and the small "bristle millipede" Polyxenus lagurus has also been recorded, together with the rather scarce woodlouse Cylisticus convexus. Sporadic moth-trapping has shown the large ranunculus Polymixis flavicincta to be present, but the adjacent Penclacwydd saltmarsh has been rather more adequately surveyed with noteworthy species such as the rosy wave Scopula emutaria and round-winged muslin Thumatha senex recorded of late.
• The mean high tide mark has also been dramatically altered - by the construction of the sea-wall or "Bulwark" (as it is locally called) which was commenced in 1808 (Davies, 1985), concurrently with the enclosure of the large area of saltmarsh - "Y Morfa Mawr" - that lay to it's landward edge. Prior to it's construction, high tide flooding would have occurred extensively in the Morfa (which, of course, means "saltmarsh"), Trostre and Llwynhendy-Bynea areas. There have however, been breaches of the bulwark, most notably in the stormy weather of October 1896 which caused severe flooding to farmland and properties. Traces of former saltmarsh creeks are still plainly visible on pastureland in the Llwynhendy area, which is still rich in fenland-carr habitats, albeit now on a small scale. The Bulwark wall (which has been extensively re-constructed in the last decade) is not without interest, being noted for the colourful display of marsh mallow Althaea officinalis and the grey sea wormwood Artemisia maritima (both of which are increasing) and occasional plants of wild celery Apium graveolens, whilst swine cress Coronopus squammatus, a very local plant in Carmarthenshire, grows on well-worn trackways. Early migrant wheatears favour the Bulwark and, in winter, flocks of greenfinches, chaffinches and occasional bramblings search. the drift-line for seeds.

There are two factors which affect the remaining marsh at present encroachment and human disturbance.

{rokbox align=|right|}images/stories/newsletters/1991_11/12.jpg{/rokbox}The encroachment of Spartina anglica (Common cord-grass) an introduced species, across the mudflat has reduced the availability of feeding areas for such birds such as dunlin, shelduck. grey plover, redshank, curlew and, to a lesser extent, pintail and mallard; all these species preferring the open mudflats. Since counts have only been made over a relatively short period, there is no proof yet that these species have declined as a direct result of Spartina encroachment, but it seems logical to assume that if the spread continues across the mudflats then valuable feeding ground will be lost. Wigeon and teal regularly feed in the Spartina zone and may be less affected. whilst snipe appear to positively benefit from the ungrazed Spartina sward. which offers them concealment. A maximum count of 704 compares favourably against tens on the heavily grazed south shore marshes. The extent of the Spartina was photographed and mapped in 1990, and further surveys will help reveal how much of threat this introduced species really is.

The effect of human disturbance is more dramatic. Shooting cones exist on the east and west sections of the saltmarsh (see map) with a central refuge zone, south of Penclacwydd. Ironically however, regular disturbance occurs in this zone due to the proximity of the two shooting zones. There is also occasional disturbance by fishermen although this is less frequent and affects a much smaller area.

Total: 13274

Dark-bellied brent geese already occur in numbers across the Inlet at Whiteford, feeding on Enteromorpha and grazing the saltmarsh. Their preferred food however, is Zostera (Eelgrass) which was re-discovered in some quantity in 1990 off Penrhyngwyn and on the mussel scars after years of presumed absence from the Burry Inlet. If this area were freed from disturbance, this food source would become available and perhaps the brent goose would be a more regular sight on the north as well as the south shores.

The preceeding table shows the highest monthly maxima for the years 198/ to 1991. This gives marginally higher figures than an average year, though mean figures are only slightly lower than those shown. Notable exceptions include increased numbers of pintail, wigeon, mallard, shoveler and species such as black-tailed godwit and greenshank which use the ponds at the Wildfowl and Wetlands Trust Centre at Penclacwydd as a roost site, but still depend on the rich feeding grounds of the scars and mudflats. The table also combines low and high tide counts and is basically intended to show the monthly usage of the area by each species. There is much interchange between the north and south shores of the Inlet which, together with seasonal turnover, probably means that the annual total of birds actually using the area is substantially greater than the totals shown in the right hand column. The continued counting in this area will help us to understand the changes that are occurring, not only to the bird populations of the north shore, but also to their habitat, and the significant role it plays as a part of the Burry Inlet.

With so much habitat having already been lost on the Burry Inlet's north shore, it is vital that what remains is not altered unless we are fully aware of the consequences that are likely to occur as a result. It is not the Spartina spread and disturbance which pose the real threat to the site but, rather developments such as construction of groynes and breakwaters which can seriously affect the ecology of the important feeding areas.

Extensive developments are envisaged for the Machynys Peninsula, including a promenade, shops and housing so it is of importance that the significance of the remaining shingle spit at Penrhyngwyn is recognized and not further modified. Perhaps the shingle could be used, together with the wildlife-rich Machynys Ponds, as a nature reserve, for quiet recreation by the many future visitors that the Peninsula will doubtless attract.

Barry Stewart, November 2, 1991

References

Davies, R.H. (1985) Machynys - some extracts from its history. Llanelli Naturalists Newsl., Dec 1985: 11-12

Prys-Jones, R.P.; Howells, R.J. & Kirby, J.S. (1989) The Abundance and Distributidn of Wildfowl and Waders on the Burry Inlet. NCC Chief Scientists Directorate commissioned research report No926

Morgan, I.K. (1990) The Machynys Ponds - an important local wildlife site threatened by development. Llanelli Naturalists Newsl., Summer 1990: 3-4