The Irish Sea (Irish: Muir Éireann or Muir Meann; Scottish Gaelic: Muir Eireann Welsh: Môr Iwerddon, Manx: Mooir Vannin) separates the islands of Ireland and Great Britain. It is connected to the Celtic Sea portion of the Atlantic Ocean by St George's Channel between Ireland and Wales, and to the north by the North Channel between Northern Ireland and Scotland which forms part of the International Hydrographic Organisation designated Inner Seas off the West Coast of Scotland marine area. The Isle of Man lies within of the Irish Sea. The sea is of significant economic importance to regional trade, shipping and transport, fishing and power generation in the form of wind power and nuclear plants. There has been long discussion of building an 80 km (50 mile) rail tunnel to link Britain and Ireland. Annual traffic between the two islands amounts to over 12 million passengers and 17 million tonnes of trade.
The Port of Liverpool handles 32 million tonnes of cargo and 734 thousand passengers a year. Holyhead port handles most of the passenger traffic from Dublin and Dún Laoghaire ports, as well as 3.3 million tonnes of freight.
Ports in the Republic handle 3,600,000 travellers crossing the Irish Sea each year, amounting to 92% of all sea travel. This has been steadily dropping for a number of years (20% since 1999), probably as a result of low cost airlines.
Ferry connections from Britain to Ireland across the Irish Sea include the routes from Swansea to Cork; Fishguard and Pembroke to Rosslare; Holyhead to Dún Laoghaire; Holyhead to Dublin; Stranraer to Belfast and Larne; and Cairnryan to Larne. There is also a connection between Liverpool and Belfast via the Isle of Man or direct from Birkenhead. The world's largest car ferry, Ulysses, is operated by Irish Ferries on the Dublin Port–Holyhead route, Stena Line also operates between Britain and Ireland. Barrow-in-Furness despite being one of Britain's largest shipbuilding centres, and being home to the United Kingdom's only submarine-building complex, is only a minor port.
There have been various tentative proposals for an Irish Sea Tunnel.
|3||Belfast||County Antrim||Ulster||276,459||Northern Ireland|
|8||Bangor||County Down||Ulster||76,851||Northern Ireland|
|12||Lytham St Annes||Lancashire||North West||41,330||England|
|19||Colwyn Bay||Conwy||Clwyd, Wales||30,265||Wales|
|20||Carrickfergus||County Antrim||Ulster||27,201||Northern Ireland|
|22||Douglas||Middle||Isle of Man||26,218||Isle of Man|
The information on the invertebrates of the seabed of the Irish Sea is rather patchy because it is difficult to survey such a large area, where underwater visibility is often poor and information often depends upon looking at material brought up from the seabed in mechanical grabs. However, the groupings of animals present depend to a large extent on whether the seabed is composed of rock, boulders, gravel, sand, mud or even peat. In the soft sediments seven types of community have been provisionally identified, variously dominated by brittle-stars, sea urchins, worms, mussels, tellins, furrow-shells, and tower-shells.
Parts of the bed of the Irish Sea are very rich in wildlife. The seabed southwest of the Isle of Man is particularly noted for its rarities and diversity , as are the horse mussel beds of Strangford Lough. Scallops and queen scallops are found in more gravelly areas. In the estuaries, where the bed is more sandy or muddy, the number of species is smaller but the size of their populations is larger. Brown shrimp, cockles and edible mussels support local fisheries in Morecambe Bay and the Dee Estuary and the estuaries are also important as nurseries for flatfish, herring and sea bass. Muddy seabeds in deeper waters are home to populations of the Dublin Bay prawn, also known as "scampi".
The open sea is a complex habitat in its own right. It exists in three spatial dimensions and also varies over time and tide. For example, where freshwater flows into the Irish Sea in river estuaries its influence can extend far offshore as the freshwater is lighter and "floats" on top of the much larger body of saltwater until wind and temperature changes mix it in. Similarly, warmer water is less dense and seawater warmed in the inter-tidal zone may "float" on the colder offshore water. The amount of light penetrating the seawater also varies with depth and turbidity. This leads to differing populations of plankton in different parts of the sea and varying communities of animals that feed on these populations. However, increasing seasonal storminess leads to greater mixing of water and tends to break down these divisions, which are more apparent when the weather is calm for long periods.
Plankton includes viruses, bacteria, plants (phytoplankton) and animals (zooplankton) that drift in the sea. Most are microscopic, but some, such as the various species of jellyfish and sea gooseberry, can be much bigger.
Diatoms and dinoflagellates dominate the phytoplankton. Although they are microscopic plants, diatoms have hard shells and dinoflagellates have little tails that propel them through the water. Phytoplankton populations in the Irish Sea have a spring "bloom" every April and May, when the seawater is generally at its greenest.
Crustaceans, especially copepods, dominate the zooplankton. However, many animals of the seabed, the open sea and the seashore spend their juvenile stages as part of the zooplankton. The whole plankton "soup" is vitally important, directly or indirectly, as a food source for most species in the Irish Sea, even the largest. The enormous basking shark, for example, lives entirely on plankton and the leatherback turtle's main food is jellyfish.
A colossal diversity of invertebrate species live in the Irish Sea and its surrounding coastline, ranging from flower-like fan-worms to predatory swimming crabs to large chameleon-like cuttlefish. Some of the most significant for other wildlife are the reef-building species like the inshore horse mussel of Strangford Lough and the inter-tidal honeycomb worm of Morecambe Bay, Cumbria and Lancashire. These build up large structures over many years and, in turn, provide surfaces, nooks and crannies where other marine animals and plants may become established and live out some or all of their lives.
There are quite regular records of live and stranded leatherback turtle in and around the Irish Sea. This species travels north to the waters off the British Isles every year following the swarms of jellyfish that form its prey. Loggerhead turtle, Ridley sea turtle and green turtle are found very occasionally in the Irish Sea but are generally unwell or dead when discovered. They have strayed or been swept out of their natural range further south into colder waters.
The estuaries of the Irish Sea are of international importance for birds. They are vital feeding grounds on migration flyways for shorebirds travelling between the Arctic and Africa. Others depend on the milder climate as a refuge when continental Europe is in the grip of winter..
Twenty-one species of seabird are reported as regularly nesting on beaches or cliffs around the Irish Sea. Huge populations of the sea duck, common scoter, spend winters feeding in shallow waters off eastern Ireland, Lancashire and North Wales.
Whales, dolphins and porpoises all frequent the Irish Sea, but knowledge of how many there may be and where they go is somewhat sketchy. About a dozen species have been recorded since 1980, but only three are seen fairly often. These are the harbour porpoise, bottlenose dolphin and common dolphin. The more rarely seen species are minke whale, fin whale, sei whale, sperm whale, northern bottlenose whale, long-finned pilot whale, orca, white-beaked dolphin, striped dolphin and Risso's dolphin..
The common or harbour seal and the grey seal are both resident in the Irish Sea. Common seals breed in Strangford Lough, grey seals in southwest Wales and, in small numbers, on the Isle of Man. Grey seals haul out, but do not breed, off Hilbre and Walney islands, Merseyside, the Wirral, Barrow-in-Furness Borough, and Cumbria.
Low-level radioactive waste has been discharged into the Irish Sea as part of operations at Sellafield since 1952. The rate of discharge began to accelerate in the mid- to late 1960s, reaching a peak in the 1970s and generally declining significantly since then. As an example of this profile, discharges of plutonium (specifically 241Pu) peaked in 1973 at 2,755TBq falling to 8.1TBq by 2004. Improvements in the treatment of waste in 1985 and 1994 resulted in further reductions in radioactive waste discharge although the subsequent processing of a backlog resulted in increased discharges of certain types of radioactive waste. Discharges of technetium in particular rose from 6.1TBq in 1993 to a peak of 192TBq in 1995 before dropping back to 14TBq in 2004. In total 22PBq of 241Pu was discharged over the period 1952 to 1998. Current rates of discharge for many radionuclides are at least 100 times lower than they were in the 1970s.
Analysis of the distribution of radioactive contamination after discharge reveals that mean sea currents result in much of the more soluble elements such as caesium being flushed out of the Irish Sea through the North Channel about a year after discharge. Measurements of technetium concentrations post-1994 has produced estimated transit times to the North Channel of around six months with peak concentrations off the northeast Irish coast occurring 18-24 months after peak discharge. Less soluble elements such as plutonium are subject to much slower redistribution. Whilst concentrations have declined in line with the reduction in discharges they are markedly higher in the eastern Irish Sea compared to the western areas. The dispersal of these elements is closely associated with sediment activity, with muddy deposits on the seabed acting as sinks, soaking up an estimated 200kg of plutonium. The highest concentration is found in the eastern Irish Sea in sediment banks lying parallel to the Cumbrian coast. This area acts as a significant source of wider contamination as radionuclides are dissolved once again. Studies have revealed that 80% of current sea water contamination by caesium is sourced from sediment banks, whilst plutonium levels in the western sediment banks between the Isle of Man and the Irish coast are being maintained by contamination redistributed from the eastern sediment banks.
The consumption of seafood harvested from the Irish Sea is the main pathway for exposure of humans to radioactivity. The environmental monitoring report for the period 2003 to 2005 published by the Radiological Protection Institute of Ireland (RPII) reported that in 2005 average quantities of radioactive contamination found in seafood ranged from less than 1Bq/kg for fish to under 44Bq/kg for mussels. Doses of man-made radioactivity received by the heaviest consumers of seafood in Ireland in 2005 was 1.10µSv. This compares with a corresponding dosage of radioactivity naturally occurring in the seafood consumed by this group of 148µSv and a total average dosage in Ireland from all sources of 3620µSv. In terms of risk to this group, heavy consumption of seafood generates a 1 in 18 million chance of causing cancer. The general risk of contracting cancer in Ireland is 1 in 522. In the UK, the heaviest seafood consumers in Cumbria received a radioactive dosage attributable to Sellafield discharges of 0.22mSv (220µSv) in 2005. This compares to average annual dose of naturally sourced radiation received in the UK of 2.23mSv (2230µSv).
Oil is produced from the Lennox and Douglas fields. It is then treated at the Douglas Complex and piped 17 kilometres to an oil storage barge ready for export by tankers. Gas is produced from the Hamilton, Hamilton North and Hamilton East reservoirs. After initial processing at the Douglas Complex the gas is piped by subsea pipeline to the Point of Ayr gas terminal for further processing. The gas is then sent by onshore pipeline to PowerGen's combined cycle gas turbine power station at Connah's Quay. PowerGen is the sole purchaser of gas from the Liverpool Bay development.
The Liverpool Bay development comprises four offshore platforms. Offshore storage and loading facilities. The onshore gas processing terminal at Point of Ayr.
Production first started at each filed as follows: Hamilton North in 1995, Hamilton in 1996, Douglas in 1996, Lennox (oil only) in 1996 and Hamilton East 2001. The first contract gas sales were in 1996.
Several potential Irish Sea tunnel projects have been proposed, most recently the "Tusker Tunnel" between the ports of Rosslare and Fishguard proposed by The Institute of Engineers of Ireland in 2004. A different proposed route between Dublin and Holyhead was proposed in 1997 by the British engineering firm Symonds. Either tunnel, at , would be by far the longest in the world, and would cost an estimated €20 billion.
Further wind turbine sites include: