BEDDMANARCH – CYMYRAN SITE OF SPECIAL SCIENTIFIC INTEREST
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What is ‘special’ about Beddmanarch – Cymyran SSSI?
Beddmanarch – Cymyran has four special features.
Marine biological interest including all three British species of eelgrass Zostera spp.
Salt marsh vegetation comprising glasswort, common saltmarsh grass, thrift, lax flowered sea lavender and sea rush. The uncommon golden samphire occurs in salt marsh communities and on parts of the rocky shoreline.
Coastal dune heath, comprising heather with sand sedge, at Traeth y Gribin and Cymyran.
Overwintering water birds including ringed plover, curlew, greenshank, red breasted merganser, goldeneye and brent geese
As well as the features listed above, Beddmanarch – Cymyran SSSI has other habitats that contribute to the special interest. These include mudflats and sandbanks, species-rich muddy gravels, tidally swept areas of bedrock, rock outcrops, shingle bars, coastal grassland and scrub. This mixture of habitats is important for much of the wildlife such as dwarf rush (Juncus capitatus), spiral tasselweed (Ruppia cirrhosa) and breeding birds, including arctic and common terns and these too are key components of the special interest of the site. Unless specified below, management of this site should aim to look after these habitats as well as the listed features of interest.
Beddmanarch – Cymyran should contain at least 60 hectares of salt marsh. . Areas of undisturbed intertidal mud, sandbank and muddy gravel should support large areas of eelgrasses in sheltered waters. The site should continue to support wintering water bird populations, including curlew, greenshank, ringed plover, goldeneye and brent geese for which the mudflats and sandbanks, along with quiet roosting areas, are essential. The arctic / common tern breeding colony, now re-established in the Inland Sea, should return to its former size (>100 pairs) following its decline in the 1970s.
The dune heath should be maintained with short heather and small bare patches conducive to dwarf rush.
What management is needed on Beddmanarch – Cymyran SSSI and why?
Although Beddmanarch – Cymyran is an excellent place for wildlife it will only remain so if the necessary management continues. CCW’s aim is to work with you to ensure that this management is carried out.
What does this mean in practice?
There are many factors that could damage the special features at Beddmanarch – Cymyran if they are not properly managed. These are the ones we regard as most important:
Tidal regime: The constriction of the tides at Four Mile Bridge and the Stanley Embankment produced a unique tidal environment in the “Inland Sea” with an oscillating fortnightly tide which means that there are often areas of mudflat available to birds when it is high tide elsewhere. Alterations to this, for instance by closure of the channels, could affect marine species in the site, by prolonging their submerged or dry periods. Equally, the removal or modification of these constrictions might restore the previous natural tidal regime but would require careful consideration.Increases in tidal flow could wash out finer sediments, changing muddy areas (preferred by eelgrass) to sandier sediments and altering muddy gravel communities. The water flume from the Stanley embankment is also an important feeding area for arctic terns.
Water quality (sediment levels): The sheltered waters of the Inland Sea offer little opportunity for wave generation and are therefore generally low in suspended sediment. This encourages the development of eelgrass.
Grazing: Coastal heath areas should ideally be lightly grazed to remove accumulated vegetation and encourage the regeneration of heather. Where this is not possible, selective mowing or occasional planned small patch controlled burning may help rejuvenate areas of old heather. Paths and tracks provide bare ground habitat for dwarf rush germination.
Nutrient (fertiliser) levels: Dune soils are characterised by low levels of nutrients (N,P,K,). Fertilisers, including atmospheric Nitrogen (NOx) pollution, encourage the growth of coarse grasses at the expense of the desired species. Supplementary feeding, e.g. with silage, has a similar impact. Use of artificial fertiliser should be avoided. Wind erosion and rabbit burrowing ensures that calcareous (shelly) sand is regularly brought to the surface to replace acid soil layer. Low levels of nutrients in the catchment area are also important to the integrity of the eelgrass beds. Increased nutrients encourage the growth of mat forming seaweed, which smother eelgrass beds.
Disturbance: Nesting birds require undisturbed conditions. Beach recreation (particularly with dogs) can threaten nesting ringed plover while windsurfing and power-boating can threaten wintering water-birds and nesting terns. Codes of conduct and zoning of activities can alleviate many of these problems.
Wildfowling
There is no evidence that the low levels of wildfowling occurring in Britain directly affect the populations of the quarry species. However, at a local scale the disturbance caused by shooting may deny feeding opportunities to wintering populations of waders and wildfowl at a critical stage in their survival. Controlled shooting occurs on parts of the site but there are agreed sanctuary zones.
Invasive species: An alien seaweed, wireweed (Sargassum muticum) has recently arrived in the Inland Sea. Although currently not a problem, its presence should be monitored. Trestle culture of Pacific oysters Crassostrea gigas has occurred in the Inland Sea and the presence of self-seeded oysters elsewhere should be monitored. Cord grass (Spartina anglica), which developed from the hybridisation of American and British precursors, colonises mudflats. However, it often exploits sedimentary changes within the estuary – in the case of this site, the restriction of natural tidal scour and resulting accumulation of sediments. Spartina will be succeeded by conventional saltmarsh vegetation. Spartina control is thus a short term and unsustainable action.
Fishing activity: Muddy gravel communities are particularly sensitive to bait digging. Good practice, such as infilling of pits and the replacement of boulders, should be encouraged in accord with the Conservation Code for Anglers.
Finally
Our knowledge and understanding of wildlife is continually improving. It is possible that new issues may arise in the future, whilst other issues may disappear. This statement is written with the best information we have now, but may have to change in the future as our understanding improves, in particular, of the possible/probable impact of climate change. Any information you can provide on the wildlife of your site, its management and its conservation would be much appreciated.
If you would like to discuss any aspect of your SSSI, or have any concerns about your SSSI, please contact your local CCW office.
Your local office is:
Countryside Council for Wales
North Region Office
Llys y Bont
Ffordd y Parc
Parc Menai
Bangor
Gwynedd
LL57 4BN
Fax: 01248 679259