Milford Haven Waterway, is a

Site of Special Scientific Interest A Site of Special Scientific Interest (SSSI) in Great Britain or an Area of Special Scientific Interest (ASSI) in the Isle of Man and Northern Ireland is a conservation designation denoting a protected area in the United Kingdom and Isle of ...

(SSSI) on

Milford Haven Waterway Milford Haven Waterway (''Welsh: Dyfrffordd Aberdaugleddau'') is a natural harbour in Pembrokeshire, Wales. It is a ria or drowned valley which was flooded at the end of the last ice age. The Daugleddau estuary winds west to the sea. As on ...

Pembrokeshire Pembrokeshire ( ; cy, Sir Benfro ) is a Local government in Wales#Principal areas, county in the South West Wales, south-west of Wales. It is bordered by Carmarthenshire to the east, Ceredigion to the northeast, and the rest by sea. The count ...

South Wales South Wales ( cy, De Cymru) is a loosely defined region of Wales bordered by England to the east and mid Wales to the north. Generally considered to include the historic counties of Glamorgan and Monmouthshire, south Wales extends westwards ...

, designated since 2002. The site is protected for a wide range of reasons, including its geology, marine environment and ecosystems, and to protect a diversity of flora and fauna.

Geology

Milford Haven Waterway is an exceptional example of a ria (a system of valleys drowned by post-glacial rise in sea level) that consists of a number of estuaries, embayments and inlets. Cliffs in the southern regions are mostly developed in rocks of the

Old Red Sandstone The Old Red Sandstone is an assemblage of rocks in the North Atlantic region largely of Devonian age. It extends in the east across Great Britain, Ireland and Norway, and in the west along the northeastern seaboard of North America. It also exte ...

, whereas the geology of the upper reaches is relatively complex. In the outer part of Milford Haven vertical cliffs are common but elsewhere the cliff profile is often composed of a slope with a vertical rock face below it, the slope being a remnant from an earlier landform - a river valley - that has not yet been eroded by the sea. In many locations stony clays mantle the middle section of the cliff profile and are exposed above the rock faces. The cliffs and foreshore at Little Castle Head provide exposures of two air-fall tuff horizons within the Sandy Haven Formation of the Lower Old Red Sandstone, Milford Haven Group. The two tuff units, the Pickard Bay Tuff Bed and the Townsend Tuff Bed, are useful stratigraphical marker horizons, particularly the latter, which can be traced across the whole of the Old Red Sandstone outcrop in South Wales. At Little Castle Head the tuffs are exposed in an area of tight folding, and comparison of logged sections across the limbs of the folds shows lateral variations in the thickness of the tuff beds and the intervening sandstone units. Faecal pellets have been preserved as unusual trace fossils at the base of, and within, the tuffs.

Biology

The Milford Haven Waterway consists of a main channel that has extensive rocky shores, with large sandy beaches in

embayments A bay is a recessed, coastal body of water that directly connects to a larger main body of water, such as an ocean, a lake, or another bay. A large bay is usually called a gulf, sea, sound, or bight. A cove is a small, circular bay with a nar ...

near the entrance, and mudflats in sheltered areas further up the channel and in muddy creeks (pills) at intervals along the length of the inlet. The foreshore supports good examples of a variety of intertidal marine habitats including muddy gravels, sheltered mud, moderately exposed sand, and sheltered rock. These shore types support a diverse range of intertidal communities, with species-rich rock pools, marine eelgrass ''Zostera'' spp. beds, and overhang and under-boulder communities. Tidal water movements are particularly strong in places, allowing the development of tide swept lower shore communities that are particularly rich, with animal species such as the breadcrumb sponge (''

Halichondria panicea ''Halichondria panicea'', commonly known as the breadcrumb sponge, is a species of sea sponge belonging to the family Halichondriidae. This is an abundant sponge of coastal areas of the North Atlantic and the Mediterranean Sea ranging from the ...

''), gooseberry seasquirt ('' Dendrodoa grossularia'') and star seasquirt (''

Botryllus schlosseri ''Botryllus schlosseri'' is a colonial ascidian tunicate. It is commonly known as the star tunicate, but it also has several other common names, including star ascidian and golden star tunicate. Colonies grow on slow-moving, submerged objects, ...

''). Other communities include beds of native oyster (''

Ostrea edulis ''Ostrea edulis'', commonly known as the European flat oyster, is a species of oyster native to Europe. In Britain and Ireland, regional names include Colchester native oyster, mud oyster, or edible oyster. In France, ''Ostrea edulis'' are known ...

'') and areas of mixed sediment supporting segmented worms of the family

Syllidae Syllidae is a family of small to medium-sized polychaete worms. Syllids are distinguished from other polychaetes by the presence of a muscular region of the anterior digestive tract known as the ''proventricle''. Syllid worms range in size from ...

. The site supports three saline

lagoon A lagoon is a shallow body of water separated from a larger body of water by a narrow landform, such as reefs, barrier islands, barrier peninsulas, or isthmuses. Lagoons are commonly divided into ''coastal lagoons'' (or ''barrier lagoons'') a ...

s; the Pickleridge lagoon within the Gann Estuary, a weired pool at Westfield Pill near

Neyland Neyland is a town and community in Pembrokeshire, Wales, lying on the River Cleddau and the upstream end of the Milford Haven estuary. The Cleddau Bridge carrying the A477 links Pembroke Dock with Neyland. Etymology The name of the town is ...

and the old Millpond within the grounds of

Carew Castle Carew Castle ( cy, Castell Caeriw) is a castle in the civil parish of Carew in Pembrokeshire, Wales. The Carew family take their name from this site and have owned the castle for more than 900 years. It is leased to the Pembrokeshire Coast Nati ...

. Saline lagoons are an unusual and rare habitat both in the UK and elsewhere supporting a number of characteristic species that are rarely found in other habitats. Species found in the above three sites include the nationally scarce tentacled lagoon worm ('' Alkmaria romijni'') and the crustacean ''

Gammarus chevreuxi ''Gammarus chevreuxi'' is a species of crustacean in the family Gammaridae. It was first described by Elsie Wilkins Sexton in 1913. The organism is very similar to ''Gammarus locusta'', but there are certain constant characteristic which set it a ...

'', along with lagoon cockle (''

Cerastoderma glaucum ''Cerastoderma glaucum'', the lagoon cockle, is a species of saltwater clam, a marine bivalve mollusc in the family Cardiidae, the cockles. This species is found along the coasts of Europe and North Africa, including the Mediterranean and Black ...

'').

The

saltmarshes A salt marsh or saltmarsh, also known as a coastal salt marsh or a tidal marsh, is a coastal ecosystem in the upper coastal intertidal zone between land and open saltwater or brackish water that is regularly flooded by the tides. It is dominated ...

within the Haven occur predominantly in sheltered areas within the upper regions of the main channel, and in the muddy creeks (pills) and embayments found at intervals along the length of the inlet. A variety of saltmarsh communities exist within the site, the most extensive being characterised by the pioneering species common cord-grass (''

Spartina anglica ''Sporobolus anglicus'' (common cordgrass) is a species of cordgrass that originated in southern England in about 1870 and is a neonative species in Britain. It was reclassified as ''Sporobolus anglicus'' after a taxonomic revision in 2014,Pete ...

'') on the lower shore. Other dominant species include sea purslane ('' Atriplex portulacoides''), common saltmarsh grass (''

Puccinellia maritima ''Puccinellia maritima'' is a species of grass Poaceae () or Gramineae () is a large and nearly ubiquitous family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos and the grasses of na ...

'') and red fescue (''

Festuca rubra ''Festuca rubra'' is a species of grass known by the common name red fescue or creeping red fescue. It is widespread across much of the Northern Hemisphere and can tolerate many habitats and climates. It is best adapted to well-drained soils in c ...

''). These grade into upper saltmarsh or brackish communities with occasional sea rush (''

Juncus maritimus ''Juncus maritimus'', known as the sea rush, is a species of rush that grows on coastlines. It is sometimes considered conspecific with '' Juncus kraussii''. It has a wide distribution across the western Palearctic realm (all of Europe, western ...

'') and saltmarsh rush (''

Juncus gerardii ''Juncus gerardii'', commonly known as blackgrass, black needle rush or saltmarsh rush, is a flowering plant in the rush family Juncaceae. Distribution ''Juncus gerardii'' is mainly a coastal species, occurring at the high tide mark on the Medit ...

''). In some areas, there is a transition zone from upper saltmarsh into areas of

reed-bed A reedbed or reed bed is a natural habitat found in floodplains, waterlogged depressions and estuaries. Reedbeds are part of a succession from young reeds colonising open water or wet ground through a gradation of increasingly dry ground. As ...

dominated by ''

Phragmites australis ''Phragmites australis'', known as the common reed, is a species of plant. It is a broadly distributed wetland grass that can grow up to tall. Description ''Phragmites australis'' commonly forms extensive stands (known as reed beds), which may ...

''. Species found within the saltmarsh include the nationally scarce lax-flowered sea-lavender (''

Limonium humile ''Limonium humile'' is a species of sea lavender ''Limonium'' is a genus of 120 flowering plant species. Members are also known as sea-lavender, statice, caspia or marsh-rosemary. Despite their common names, species are not related to the ...

'') and the one-flowered glasswort ('' Salicornia pusilla''). Ancient woodland, dominated by sessile oak (''

Quercus petraea ''Quercus petraea'', commonly known as the sessile oak, Cornish oak, Irish Oak or durmast oak, is a species of oak tree native to most of Europe and into Anatolia and Iran. The sessile oak is the national tree of Ireland, and an unofficial emble ...

''), fringes areas of the main channel. This relict woodland becomes more extensive at

Lawrenny Lawrenny is a village and parish in the community and electoral ward of Martletwy in the county of Pembrokeshire, Wales. It is on a peninsula of the River Cleddau estuary upriver from Milford Haven where it branches off towards the Cresswell ...

, which can be dated back to at least 1600 when extensive oak woods once clothed all the shoreline of the 'drowned valley' system of Milford Haven. Wild service-tree (''

Sorbus torminalis ''Sorbus torminalis'', with common names wild service tree, chequers, and checker tree, is a species of tree in the mountain Fraxinus, ash or rowan genus (''Sorbus'') of the rose family (Rosaceae), that is native to Europe, parts of northern Afr ...

'') is frequent on the lower slopes and the ground flora is rich with ancient woodland

indicator species A bioindicator is any species (an indicator species) or group of species whose function, population, or status can reveal the qualitative status of the environment. The most common indicator species are animals. For example, copepods and other sma ...

. The woodland supports a large number of interesting

lichen A lichen ( , ) is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship.Arthonia astoidestra''. Viburnum lantana a1

The various habitats within the Haven support a rich assemblage of flowering plants. The site supports some of the largest populations in Pembrokeshire of species that have seen a marked decline at the national level over recent years. These populations include dwarf eelgrass (''

Zostera noltei ''Zostera noltii'' is a species of seagrass known by the common name dwarf eelgrass. It is found in shallow coastal waters in north western Europe, the Mediterranean Sea, Black Sea, Caspian Sea and Aral Sea and on islands in the Atlantic off th ...

''), marsh pea (

Lathyrus palustris ''Lathyrus palustris'' is a species of wild pea known by the common name marsh pea. It is native to Europe, Asia, and North America. It is a perennial herb with leaves made up of oval-shaped or oblong leaflets a few centimeters long. It has bran ...

), spurge-laurel (''

Daphne laureola ''Daphne laureola'', commonly called spurge-laurel, is a shrub in the flowering plant family Thymelaeaceae. Despite the name, this woodland plant is neither a spurge nor a laurel. Its native range covers much of Europe and extends to Algeria, Mo ...

'') and wayfaring tree (

Viburnum lantana ''Viburnum lantana'', the wayfarer or wayfaring tree, is a species of ''Viburnum'', native to central, southern and western Europe (north to Yorkshire in England), northwest Africa, and southwestern Asia.Blamey, M. & Grey-Wilson, C. (1989). ''Flo ...

). Other nationally rare or scarce flowering plants include rock sea-lavender ( Limonium procerum spp. cambrense), musk stork's-bill ('' Erodium moschatum''), marsh mallow (''

Althaea officinalis ''Althaea officinalis'', the marsh mallow or marshmallow, is a species of flowering plant indigenous to Europe, Western Asia and North Africa, which is used in herbalism and as an ornamental plant. A confection made from the root since ancient ...

'') and chamomile (''

Chamaemelum nobile ''Chamaemelum nobile'', commonly known as chamomile (also spelled camomile), is a low perennial plant found in dry fields and around gardens and cultivated grounds in Europe, North America, and South America. Its synonym is ''Anthemis nobili ...

''). The coastal slopes throughout the Haven support a rich assemblage of

moss Mosses are small, non-vascular flowerless plants in the taxonomic division Bryophyta (, ) '' sensu stricto''. Bryophyta (''sensu lato'', Schimp. 1879) may also refer to the parent group bryophytes, which comprise liverworts, mosses, and hor ...

es and

liverworts The Marchantiophyta () are a division of non-vascular land plants commonly referred to as hepatics or liverworts. Like mosses and hornworts, they have a gametophyte-dominant life cycle, in which cells of the plant carry only a single set of ge ...

. The nationally rare moss ''

Tortula cuneifolia ''Tortula'' is a genus of mosses in the family Pottiaceae. Species There are different classifications for the species included in the genus. The delimitation of genus Tortula is problematic and was subject to a number of alterations in the pas ...

'' is another species that has undergone a significant decline in Britain in recent years, has been recorded within the site. Nationally scarce lower plants include the mosses '' Bryum torquescens'' and '' Weissia perssonii'' along with the liverwort '' Cololejeunea minutissima''. The saltmarsh and mudflats within the Haven support significant numbers of over-wintering

wildfowl The Anatidae are the biological family of water birds that includes ducks, geese, and swans. The family has a cosmopolitan distribution, occurring on all the world's continents except Antarctica. These birds are adapted for swimming, floating on ...

and

wader 245px, A flock of Dunlins and Red knots">Red_knot.html" ;"title="Dunlins and Red knot">Dunlins and Red knots Waders or shorebirds are birds of the order Charadriiformes commonly found wikt:wade#Etymology 1, wading along shorelines and mudflat ...

s. This number rises during particularly hard winters, when the mild Pembrokeshire climate results in the Haven population becoming augmented by wildfowl and waders coming in from other estuaries to the east that have become frozen. Species of special interest within the Haven include

little grebe The little grebe (''Tachybaptus ruficollis''), also known as dabchick, is a member of the grebe family of water birds. The genus name is from Ancient Greek ''takhus'' "fast" and ''bapto'' "to sink under". The specific ''ruficollis'' is from Latin ...

(''Tachybaptus ruficollis''),

shelduck The shelducks, most species of which are found in the genus ''Tadorna'' (except for the Radjah shelduck, which is now found in its own monotypic genus ''Radjah''), are a group of large birds in the Tadorninae subfamily of the Anatidae, the biologi ...

(''Tadorna tadorna''),

Eurasian wigeon The Eurasian wigeon or European wigeon (''Mareca penelope''), also known as the widgeon or the wigeon, is one of three species of wigeon in the dabbling duck genus ''Mareca''. It is common and widespread within its Palearctic range. Taxonomy Th ...

(''Anas penelope''),

Eurasian teal The Eurasian teal (''Anas crecca''), common teal, or Eurasian green-winged teal is a common and widespread duck that breeds in temperate Eurosiberia and migrates south in winter. The Eurasian teal is often called simply the teal due to being th ...

(''Anas crecca''),

dunlin The dunlin (''Calidris alpina'') is a small wader, formerly sometimes separated with the other "stints" in the genus ''Erolia''. The English name is a dialect form of "dunling", first recorded in 1531–1532. It derives from ''dun'', "dull brown ...

(''Calidris alpina'') and

Eurasian curlew The Eurasian curlew or common curlew (''Numenius arquata'') is a very large wader in the family Scolopacidae. It is one of the most widespread of the curlews, breeding across temperate Europe and Asia. In Europe, this species is often referred t ...

(''Numenius arquata''). The Haven makes up the lower part of the Cleddau catchment, an area recognised as being one of the most important places in southern Britain for

otter Otters are carnivorous mammals in the subfamily Lutrinae. The 13 extant otter species are all semiaquatic, aquatic, or marine, with diets based on fish and invertebrates. Lutrinae is a branch of the Mustelidae family, which also includes wea ...

Within the vicinity of the Haven are important bat breeding sites, supporting internationally important populations of

greater horseshoe bat The greater horseshoe bat (''Rhinolophus ferrumequinum'') is an insectivorous bat of the genus '' Rhinolophus''. Its distribution covers Europe, Northern Africa, Central Asia and Eastern Asia. It is the largest of the horseshoe bats in Europe an ...

s, as well as nationally important numbers of lesser horseshoe bats. Broadleaved woodland and scrub, along with estuarine and grassland habitats, that border the main channel and its various embayments and inlets, provide essential feeding grounds for the bats, as well as flight paths between sites. The horseshoe bats and other bat species also roost in buildings and caves (adjacent to and within the site) during the year. These roosts are used by bats as daytime roosts, night-feeding roosts, or as winter hibernacula. Saltmarsh on the site supports a number of nationally scarce invertebrate species including comb footed spider ('' Enoplognatha mordex''), the ground and short winged mould beetles ('' Bembidion laterale'' and '' Brachygluta simplex''), the weevils '' Polydrusus pulchellus'' and '' Notaris bimaculatus'', the hoverfly ''

Platycheirus immarginatus ''Platycheirus immarginatus'', the Comb-legged Sedgesitter, is a common species of hoverfly. It is found in parts of northern Europe and northern North America. Description For terminologySpeight key to genera and glossary ;Size ;Head The fa ...

'' and the cranefly ''Limonia'' (Dicranomyia) ''complicata''. Blackthorn (''

Prunus spinosa ''Prunus spinosa'', called blackthorn or sloe, is a species of flowering plant in the rose family Rosaceae. The species is native to Europe, western Asia, and regionally in northwest Africa. It is locally naturalized in New Zealand, Tasmania, ...

'') scrub in places supports nationally important populations of brown hairstreak butterfly ('' Thecla betula''), a species that has undergone a rapid decline throughout Britain during the last thirty years.

Ownership and overlapping protections

Parts of the site are owned by

Pembrokeshire County Council Pembrokeshire County Council ( cy, Cyngor Sir Penfro) is the governing body for Pembrokeshire, one of the Principal Areas of Wales. Political control The first election to the council was held in 1995, initially operating as a shadow authorit ...

and the

National Trust The National Trust, formally the National Trust for Places of Historic Interest or Natural Beauty, is a charity and membership organisation for heritage conservation in England, Wales and Northern Ireland. In Scotland, there is a separate and ...

; both organisations lease parts of the site to the

Wildlife Trust of South and West Wales The Wildlife Trust of South and West Wales (WTSWW) ( cy, Ymddiriedolaeth Natur De a Gorllewin Cymru) is a Wildlife Trust in south and west Wales, one of 46 such Trusts in the United Kingdom. History Forerunner of the WTSWW, the former West Wal ...

. The

Crown Estate The Crown Estate is a collection of lands and holdings in the United Kingdom belonging to the British monarch as a corporation sole, making it "the sovereign's public estate", which is neither government property nor part of the monarch's priva ...

owns the majority of the foreshore, which is leased to Pembrokeshire County Council and the

Pembrokeshire Coast National Park Pembrokeshire Coast National Park ( cy, Parc Cenedlaethol Arfordir Penfro) is a national park along the Pembrokeshire coast in west Wales. It was established as a National Park in 1952. It is one of three national parks in Wales, the others bei ...

. Sporting rights are leased to the Pembrokeshire Wildfowlers Association and the Pembroke Rod and Gun Club. Approximately two-thirds of the site lies within the Pembrokeshire Coast National Park. The area covered by the Wild Birds (Cleddau Sanctuary) Order 1970 lies within the site, which is also part of the Pembrokeshire Marine/Sir Benfo Forol candidate Special Area of Conservation for its estuary, shallow inlets and bays, reefs, Atlantic salt meadows, otter, intertidal mudflats and sandflats and lagoon features. The otter and greater and lesser horseshoe bats are listed in Annex IIa of the EC Habitats Directive (Directive 92/43/EEC on the Conservation of Natural Habitats and of Wild Fauna and Flora). The tentacled lagoon worm Alkmaria romijni, otter and greater and lesser horseshoe bats are listed under Schedule 5 of the

Wildlife and Countryside Act 1981 The Wildlife and Countryside Act 1981 is an Act of Parliament in the United Kingdom implemented to comply with European Council Directive 79/409/EEC on the conservation of wild birds. In short, the act gives protection to native species (especia ...

. The entire SSSI falls within a

Marine Character Area A Marine Character Area (MCA) is a marine geographic area around the Welsh coastline, designated by Natural Resources Wales for the purposes of characterising the key natural, cultural and perceptual influences on the defined area. MCAs are part o ...

, used by the Welsh government to "highlight the key natural, cultural and perceptual influences that make the character of each seascape distinct and unique". It also falls within the Pembrokeshire Marine Special Area of Conservation, a European Marine Site designated in 2004.

Subdivisions

The site is divided, for management reasons, into 11 component areas covering the shores and mudflats of most of the

ria A ria (; gl, ría) is a coastal inlet formed by the partial submergence of an unglaciated river valley. It is a drowned river valley that remains open to the sea. Definitions Typically rias have a Drainage system (geomorphology)#Dendritic dr ...

from its mouth at Dale Point on the north shore and

Thorn Island Thorne Island is a rocky islet and part of the community of Angle, Pembrokeshire, Wales, with an area of , dominated by a coastal artillery fort built to defend the Milford Haven Waterway in the mid-19th century. It has been the site of a numbe ...

on the south, to the upper reaches of the

Daugleddau The River Cleddau ( cy, Afon Cleddau) consists of the Eastern and Western Cleddau rivers in Pembrokeshire, west Wales. They unite to form the Daugleddau estuary and the important harbour of Milford Haven. The name of the combined estuary – ...

Haverfordwest Haverfordwest (, ; cy, Hwlffordd ) is the county town of Pembrokeshire, Wales, and the most populous urban area in Pembrokeshire with a population of 14,596 in 2011. It is also a community, being the second most populous community in the county, ...

in the west and

Blackpool Mill Blackpool Mill is a 19th century flour mill in the community of Martletwy, in the Pembrokeshire Coast National Park. It sits to the west of Blackpool Bridge on the southern bank of the Eastern River Cleddau, downstream from Canaston Bridge. Built ...

in the north-east. The areas are: *Angle Bay *Carew and Cresswell Rivers *Cosheston Pill *Dale Point to Musselwick Point *Daugleddau *Lawrenny Wood *Littlewick Point to Brunel Quay *Milford Haven South *Musselwick Point to Littlewick Point *Pembroke River *Sandy Haven

Notes

References

Attribution

*{{OGL-attribution, {{cite web , author=Natural Resources Wales, date=2002, url=https://naturalresources.wales/media/639589/SSSI_0282_Citation_EN0010ded.pdf , title=Site of Special Scientific Interest Summary Citation: Milford Haven Waterway , accessdate=13 January 2021 Sites of Special Scientific Interest in Pembrokeshire Valleys of Pembrokeshire 2002 establishments in Wales