Importance of the Ocean

7/30/2019 Importance of the Ocean

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Importance of the Ocean

Throughout history humans have been directly or indirectly influenced by the oceans. Ocean watersserve as a source of food and valuable minerals, as a vast highway for commerce, and provide aplace for both recreation and waste disposal. Increasingly, people are turning to the oceans for their

food supply either by direct consumption or indirectly by harvesting fish that is then processed forlivestock feed. It has been estimated that as much as 10% of human protein intake comes from theoceans. Nevertheless, the food-producing potential of the oceans is only partly realized. Otherbiological products of the oceans are also commercially used. For example, pearls taken fromoysters are used in jewelry, and shells and coral have been widely used as a source of buildingmaterial.

Ocean water is processed to extract commercially valuable minerals such as salt, bromine, andmagnesium. Although nearly 60 valuable chemical elements have been found dissolved in oceanwater, most are in such dilute concentrations that commercial extraction is not profitable. In a fewarid regions of the world, such as Ascension Island, Kuwait, and Israel, ocean water is desalinatedto produce freshwater.

The shallow continental shelves have been exploited as a source of sands and gravels. In addition,extensive deposits of petroleum-bearing sands have been exploited in offshore areas, particularlyalong the Gulf and California coasts of the United States and in the Persian Gulf. On the deepocean floor manganese nodules, formed by the precipitation of manganese oxides and othermetallic salts around a nucleus of rock or shell, represent a potentially rich and extensive resource.Research is currently being conducted to explore nodule mining and metallic extraction techniques.Ocean water itself could prove to be a limitless source of energy in the event that nuclear fusionreactors are developed, since the oceans contain great quantities of deuterium.

The oceans also have become more important for recreational use, as each year more people areattracted to the sports of swimming, fishing, scuba diving, boating, and waterskiing. Ocean pollution,meantime, has escalated dramatically as those who use the oceans for recreational and commercial

purposes, as well as those who live nearby, have disposed of more and more wastes there(seewater pollution).

Introduction

FROM the first shellfish gathering shore-dwellers millennia ago to the coastal communities of today:

throughout history the people of Ireland have relied on the seas and coasts to provide for their

spiritual, social and economic well-being.

The oceans and seas have long been viewed as inexhaustible reservoirs of

living and non-living natural resources and as limitless sinks for the

disposal of our industrial, agricultural and domestic wastes. We have only

recently begun to acknowledge that there are limits to the extraction of

fish and minerals and that marine ecosystems are vital and not immune

to the effects of human activities taking place on land or at sea, and

cannot withstand the pollution we put in.
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It is now apparent that the oceans and seas are undergoing profound human-induced alteration and

that the scale, intensity and speed of such change has increased tremendously in the past century as

a consequence of growing human populations, higher levels of consumption and increasingly potent

technologies.

The symptoms of the resulting ecological stress include overexploited fishstocks, hazardous substances in the food chain, immune system disorders in

marine mammals, genetic pollution of wild salmon populations, invasive

exotic species disrupting coastal ecosystems, ancient deep-sea corals and

seabed habitats damaged by fishing gear, nutrient pollution and harmful

algal blooms, radioactive hotspots, oil spills, undersea noise pollution,

littered beaches, eroded dunes, diminished coastal wetlands, disturbed wildlife breeding sites, and the

potentially enormous effects of global climate change on marine ecosystems, habitats, species and

human settlements along the coast.

Together these threats and pressures make a potent, though little understood, synergistic complex

that according to growing scientific consensus poses an unprecedented threat to the stability of

ecosystems and the existence of species on a worldwide scale. By allowing these threats to the oceans

and by adding to the related pressures, we jeopardise our own health and well-being.

Oceans Policy

PEOPLE in Ireland use and connect with the ocean for a wide range of social, economic and cultural

reasons. There is currently no clear statement at national level of what it is that the Irish individually

and collectively value about the seas and coasts, and what relative priority should be attached to

different options at different times and perhaps different places.


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As a nation of islands, Ireland has some 7,500 kilometres of coastline, a correspondingly large

exclusive economic zone (EEZ) covering some 465,000 square kilometres of the North-East Atlantic,

and an even larger claim on the offshore continental shelf covering some 900,000 square kilometres

of seabed.

Ireland's marine environment is contiguous with the global ocean. Ireland extends influence not only

over a large EEZ but also over the wider North-East Atlantic region and (in the context of Irish fishing

vessels) the high seas (international waters) plus the sovereign waters of developing countries,particularly in West Africa.

Over 50 per cent of Ireland's population live within 10 kilometres of the coast.

There are nearly 20 inhabited offshore islands. The five largest urban

conurbations are located along the coastline. There are 130 fishing harbours

and 10 major shipping ports. Ireland's small open economy is strongly

dependent on external trade and sea transport to reach its main markets. In

addition to fisheries, aquaculture and shipping, the coastal zone supports

strategic sectors such as heavy industry, power generation and tourism.

From the coastal margins to the distant offshore, these factors create pressures that need to be

managed. A relatively small population in Ireland has helped to maintain a healthy sea, but it also

restricts the resource base of funding and skills available for effective management activities.

Clearly it is vital that Ireland develop a comprehensive, integrated strategy for the protection of the

marine environment, the sustainable use of its natural resources and the conservation of its biological

diversity (biodiversity), principally its component marine and coastal ecosystems, not only for the


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well-being of the enormous variety of marine wildlife but also for the coastal communities that depend

upon the seas and coasts for their livelihoods.

Marine Work Group Ireland was established the to develop a comprehensive policy that addresses the

numerous threats and related pressures concerning the marine environment and biodiversity of Irish

waters. The task set was to define a collective vision and identify the values we believe should informpolicy- and decision-making about the marine area under Ireland's jurisdiction and beyond.

The resulting policy would be a first step toward a much more inclusive national dialogue and process

of developing an overarching framework, or Oceans Policy, which will serve in conjunction with the

development of the European Marine Strategy at European Union level to guide and rationalise the

integrated management of our interaction with the oceans, seas, islands and

coastal areas.

In recent years, there has been increasing recognition of the need to

effectively manage the impact of human activity on the marine environment

and its biodiversity. Ireland ratified the hugely important United Nations

Convention on the Law of the Sea (UNCLOS) in 1996. UNCLOS is the

international framework in which nations agree to take responsibility for

managing their own marine environment. Equally important are the overarching United Nations

Convention on Biological Diversity, 1992 (CBD) and the relevant objectives of the Plan of

Implementation agreed by the World Summit on Sustainable Development in 2002. Ireland is also a

contracting party to the 1992 Convention for the Protection of the Marine Environment of the North-

East Atlantic (OSPAR Convention) an appropriately strong regional seas agreement. Other landmark

agreements include the EU Habitats Directive[1], Birds Directive[2] and Water Framework

Directive[3]. These and other agreements including in particular the forthcoming European Marine

Strategy as proposed by the European Commission[4] that are relevant both to Ireland'sinternational obligations and the management of the marine environment under its jurisdiction have a

crucial role to play in shaping Irish Government policy.

The State has numerous pieces of legislation related to the use of the ocean and its resources, some

of which work to protect the marine environment, some of which do not. There are laws about

commercial fishing, petroleum exploration and production, shipping, recreational and passenger craft,

harbours and ports, marine nature reserves, sewage disposal, dumping at sea, etc. This framework is

complicated and piecemeal, often contradictory and contains significant gaps; most of the laws do not

recognise other users of the sea or the special natural values of the ocean. There is a corresponding

lack of clearly defined goals to give direction to decisions about the ocean and guidance when those

laws conflict.

Clearly there is a need to fill this vacuum with a modern, coherent, integrated national oceans

strategy comprising firstly principles and objectives, secondly actions and policies for the future

protection of Ireland's marine environment, sustainable use of its natural resources and conservation

of its biodiversity: an Oceans Policy.
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The Government has a leading role to play in facilitating the ecologically

sustainable development of ocean resources by devising, developing and

implementing modern oceans management. An Oceans Policy would

provide a national strategy and policy framework for the integrated

management, according to ecosystem principles, of all human activities

that affect marine, coastal and estuarine environments in a way that

protects the natural and national heritage, conserves biodiversity, and ensures the sustainable use of

living and non-living natural resources.

An Oceans Policy would focus on issues associated with managing the marine environment within the

jurisdiction of Ireland, including issues associated with the inter-tidal zone and the interaction between

land management and the quality status of the marine environment. It would also take account of

relevant international obligations and explicitly address issues relating to Ireland's management of, or

involvement in, the wider North-East Atlantic region and other regional seas.

An Oceans Policy would allow a prior understanding of how, why and by whom choices will be made. It

would act as a backbone to support a logical framework of national legislation and policies that

together form a complete and functional structure that acknowledges and accommodates the wide

range of legitimate and existing interests, values and activities that the people of Ireland have in

relation to "their" marine environment. It would help State Organisations to manage conflicts between

different management regimes and marine resource user groups.

An Oceans Policy would be dynamic and far-sighted, and be capable of positioning Ireland to both take

advantage of new opportunities, such as ocean related renewable energy power generation, and shape

reaction to new and/or increased levels of threats and pressures on the marine environment. It would

ensure that exploiting new opportunities could be accomplished without putting at risk what is truly

valued about the marine environment and our national marine, coastal and maritime heritage. Itwould define the quality of what is passed on to succeeding generations and provide them with a

robust basis to meet their own challenges.

Importance of the Sea

Oceans, seas, islands and coastal areas form an integrated and essential component of the Earth's

ecosystem and are critical for global food security and for sustaining economic prosperity and well-

being of many national economies, particularly in developing countries.[1]

THE enormous size, diversity and complexity of the marine environment over which Ireland claims

jurisdiction presents government and civil society with many challenges regarding its protection and

management.

In order to responsibly and effectively manage the health of the marine environment, we must first

understand its character and recognise that "the environment" is not itself an entity that we can

manage it is a dynamic and diverse system that changes naturally, heedless of our desire to

manipulate and control its behaviour. Only the impact of human influence on the marine environment

can be managed, and that usually requires us to modify our behaviour.
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The marine environment is a complex entity comprising

distinct but interconnected components, many of which

are of enormous physical dimension: the coastline,

seabed, its subsoil, the water column, sea surface and

overlying atmosphere, the abundance and variety of

marine life, habitats and ecosystems[2] within the marine environment, the substances, energy,

objects and constructions we introduce to it, and the human activities that take place on, in, over and

around it.

Oceans and seas cover over 70 per cent of the Earth's surface. They have a large influence on global

heat transport and precipitation (climate and weather patterns). They provide a large proportion of the

oxygen we breathe and are a major source of biodiversity[3] and natural resources.

The protection and management of the natural resource base are of fundamental importance to

achieving ecologically sustainable economic and social development. Nearly one billion people

worldwide already rely on oceans and seas as a major source of nutrition. This dependence will

continue to grow as human populations increase. The degradation of the oceans and seas seriously

threatens food security and the eradication of poverty across the globe.

In addition to food, oceans and seas provide us with a wide variety of goods, services and other

benefits, including oil and gas, renewable energy generation potential, transportation corridors and

recreational opportunities.

A healthy society depends on healthy seas and coasts.

Healthy Society

WE make use of the marine environment as a source of food, oil and gas, aggregates, bio-

pharmaceuticals and other natural resources. It provides a means of transport and, potentially,

unlimited generation of renewable energy. It is a sink for the disposal of sewage, agricultural and

other wastes. It hosts important productive sectors, providing revenue and employment for thousands

of people. The seas and coasts also support a complex infrastructure needed by our modern society

and economy in order to function. Other less practical uses and requirements are no less real and

important. The seas and coasts provide opportunities for relaxation and recreation that are

fundamental to our lifestyle and sense of well-being.

Economic activity

A significant amount of Ireland's economic activity is based on the marine environment and the

relative importance to the economy of marine-based activities continues to rise. This is reflected in the

1.7 billion total Government expenditure on the marine and natural resources sector under the

National Development Plan 2000-2006.
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In 1998 Ireland's combined marine sector contributed nearly 1.2 billion to the nationaleconomy and provided full and part-time employment for over 32,000 people. The

Government has previously forecast this to increase to 1.75 billion and 39,000 jobs in

2003[1].

Some 99 per cent of Ireland's external trade passes through ports: about three-quarters of itthrough ports in the Republic, the remainder through ports in the North. Ireland's domestic

merchant fleet may only be small, comprising just 29 or so large vessels, but it nevertheless

undertakes a significant amount economic activity.

In 2000 the Irish fishing fleet comprised 1,274 boats, including aquaculture service vessels.They landed some 272,480 tonnes of sea fish worth about 189 million and these figures

exclude landings made by foreign boats into Irish ports. The Irish fleet currently accounts for

approximately 30-35 per cent of the total international landings of fish and shellfish from the

region[2] that includes the seas around Ireland and off the west coast of Britain.

Since fish farming in coastal waters (i.e. marine aquaculture, or mariculture) began in Irelandin the 1970s, finfish and shellfish farms have spread to nearly every coastal county. In 1999

the value of aquaculture output accounted for one-third of the value of total seafood supply.

In 2000 Irish aquaculture production[3] was some 51,250 tonnes valued at over 95 million.

Aquaculture output is projected to increase to just over 97,000 tonnes valued at nearly 176

million in 2008. The Government aims to increase annual Irish aquaculture production to

160,000 tonnes by 2017.

In 2001 Irish exports of fish and fish products were worth about 433 million. Total employment on a full and part-time basis in the marine food sector, which embraces all

economic activities deriving from the biologically productive capacity of the seas, is around15,720 persons. Of these, aquaculture employs an estimated 2,200 persons, and fish

processing some 4,000 persons.

Marine tourism and recreation are also a key economic activity. Over 50 per cent of Irishadults engage in water-based leisure activities, spending over 380 million annually and

supporting employment for 11,000 people. In 1998 the Government estimated that a further

350,000 people would start to participate in water-based activities if facilities are developed

and improved, resulting in 8,000 new jobs in the sector[4].

(Sources:Bord Iascaigh Mhara (BIM); CSO Fishery Statistics 2000, 10/1/02; Ireland's Environment: A

Millennium Report, Environmental Protection Agency, April 2000;FIS/Fish Information & Services)

Infrastructure

As an island nation Ireland is both separated from and connected to the world by the sea. The

connections are critical to Ireland's society and economy. Our reliance on marine infrastructure makes

the secure provision of marine infrastructure services a matter of national importance.
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Ireland's small open economy is strongly dependent on external

trade and sea transport to reach its main markets. The sea-lanes

of international shipping provide the means to export and import

raw materials and products useful to a modern society and

economy. By volume, 99 per cent of Ireland's external trade

passes through ports. In 2000 this amounted to 46 million tonnes.

Underwater "interconnector" gas pipelines between Ireland and

Britain ensure a continuity of natural gas supplies sourced from as far a field as Turkey and Siberia.

Underwater cables distribute high-voltage electricity to inhabited offshore islands and carry vital

telecommunication links that connect us with the world.

The deployment of pipelines and cables, and our economic and social reliance on them, are likely to

increase in coming years thus giving rise to increasing conflict between different marine user groups.

For example, the establishment of cable and pipeline protection zones and corridors to prevent

damage from ships' anchors and certain fishing techniques clearly limits fishing activities for

commercially valuable species, whilst breaches of infrastructure protection zones leading to damage

can result in considerable direct and indirect cost to society.

Energy related marine infrastructure is, and will remain vitally important to

the economy. Ireland's current heavy dependence on fossil fuels requires

considerable infrastructure to receive, handle and utilise imports by sea of

crude oil, fuel oil and coal for example, the Whiddy Island oil terminal in

Bantry Bay, the Money Point coal-fired and Tarbert heavy fuel oil-fired power

stations on the Shannon Estuary, and the Whitegate Refinery in Cork

Harbour. Infrastructure is also increasingly being put in place to service offshore exploration and

facilitate the production and transport of oil and gas for example, the Kinsale Head and Ballycottongas field platforms and pipelines, and the proposed Corrib gas field subsea wellheads and pipeline.

Now, due principally to the global effort to ameliorate human-induced climate change, Ireland faces an

inevitable shift toward offshore sourced renewables such as wind, wave, tidal and solar, and the

development of associated infrastructure including offshore windmill parks, floating solar collecting

platforms, and tidal current and coastal wave energy generators. Clearly there is an urgent need for a

national strategy to guide the transition from a fossil fuel based to a renewables based marine

infrastructure.

Non-economic activity

The sea is an important and often overlooked facet of Ireland's unique identity and the well-being of

its coastal communities. As an island people, the Irish have long had a cultural as well as physical

relationship with the seas and coasts. Many people have strong feelings of connection with the marine

environment. Some would describe their connection as spiritual. Value is placed on the spaciousness,

vastness, silence, power, wilderness and otherworldliness of the sea. For many of us, such values

form part of our worldview and are commonly translated into personal practices of conservation and

care.


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We use and value the seas and coasts for a variety of non-economic reasons, which ultimately

enhance our lifestyles. Although qualities such as intrinsic worth, wilderness, spiritual value, well-

being, social value and ecosystem health are not as easy to quantify as the value of economic use

they are no less important to people.

Of those who connect directly with the seas and coasts, recreational and leisure users are, and willremain by far the most numerous. Whether swimming, sailing, diving, surfing, fishing, building

sandcastles, playing ball games, walking on the beach or just looking out to sea for many of us this

use of the marine environment brings with it a sense of well-being variously described as peace,

relaxation, calm, pleasure, invigoration and renewal.

People from all walks of life enjoy the common purpose of

recreation and agree that clean water and beaches, and

unimpeded access to the seas and coasts are important.

However, competition for, and conflict over space and resources

between different users of the marine environment is often

associated with marine-based recreation in its various forms. In a

growing number of cases, different forms of use cannot exist

safely in the same place at the same time, for example the use of

water jet skis in areas used by bathers. As more and more people

congregate in the same parts of the coastline for recreational

purposes, tensions are likely to increase.

But despite our dependence on the marine environment, little is

currently being done to reverse the failing health of our seas and coasts.

Healthy Seas & Coasts

LIFE in the sea is dominated by the interaction of chemical processes and

physical forces (tides, currents and weather) as demonstrated by

phenomena such as global ocean circulation. The North-East Atlantic

supports potentially some of the most productive fisheries in the world.

However, commercially important fish species represent only a small part

of such a large marine ecosystem. All marine ecosystem components link

together in a food chain, or more accurately, food web. Critical to the health of the seas around

Ireland are communities of seabed organisms and free-floating plants (phytoplankton) and animals

(zooplankton), which are important sources of food for fish and other marine animals such as molluscs

and crustaceans. These in turn are consumed by higher-ranking predators including fish such as tunasand sharks, birds, seals, cetaceans (porpoises, dolphins and whales) and humans.

Protecting the health of marine ecosystems is fundamental to sustaining marine and coastal

biodiversity, economic usefulness, and the intrinsic, cultural, recreational and aesthetic values that we

hold in relation to the marine environment. But what do we mean by "healthy" seas and coasts?


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The subject of what constitutes a healthy marine environment is as much a societal issue as it is a

scientific one. "Health" is probably better expressed as the "overall ecological quality"[1] of a marine

ecosystem. In practice, society determines the desired ecosystem state by taking into account, with

the help of science, the biological community, natural geographic, hydrographic and climatic factors as

well as physical and chemical conditions including those resulting from human activities. In fact, this is

the starting point for the development of an ecosystem-based approach to management.

One thing is certain: there is no such thing as a pristine marine environment. Humans have been

excessively interfering with marine ecosystems for too long, causing species and population

extinctions and altering habitats. Clearly it is pragmatic to call for the restoration to, and maintenance

of marine ecosystems at a "near-to-pristine-as-practicable" state based on identifiable reference levels

of individual elements of ecological quality where the influence of human activity on the ecological

system is minimal, for example:

The historic size of a fish stock before intensive exploitation commenced. The historic level of mercury in estuary sediments before industrial development takes place. The current number of seals or seabirds in a population (no historical data).

In summary, seas and coasts are healthy when the critical ecological processes, the ecosystem

interactions, and the physical, chemical and biological environment are near-to-pristine-as-practicable.

Interconnectedness

Governance and management of the marine environment must reflect the fundamental

interconnectedness of the ocean, land and atmosphere indispensable components of the Earth's

ecosystem and be responsive to the dynamic biological and physical interactions of the seas and

coasts.

The land-based activities of an increasing human population have a

significant impact on the health of the oceans. It is the sea-land interface

(the coastal zone) where the marine environment is often under the most

stress from coastal development, sewage discharge, agricultural fertiliser

and effluent runoff, climate change related coastal erosion, inundation and

storm damage, and so forth. Spatial planning and decision-making regarding

land-based activities must take into account their effect on marine ecosystems by implementing a

"mountains-to-the-sea" approach to management.

Marine and coastal area management regimes have proved unrealistic and ineffectual when based on

imposed geographical limits or arbitrary administrative subdivisions such as the low-tide mark or the

200 nautical mile "outer limit" of State jurisdiction, which cut across natural ecosystem boundaries

and ignore the interaction of biophysical systems. Instead, the integrated management of the impact

of human influence on the marine environment must be holistic and take an ecosystem-based

approach that reflects natural systems and their interconnectedness and takes into account the overall
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cumulative, synergistic effects locally, regionally and globally of all human interaction with the

marine environment.

Marine Environments

Deep-sea

IT was once believed that in the open ocean beyond the continental shelf edge, the bathyal regions

and deep ocean floor were deserts of sedimentary ooze that supported few life forms. However,

surveys have shown that deep-sea ecosystems possess an unexpectedly high species abundance and

diversity. The deep seabed off Ireland's Atlantic seaboard supports an amazing abundance and variety

of life including cold-water corals, sponges, sea slugs, sea urchins, starfishes, deep-water fishes and

many other benthic organisms.

Other research has gone some way to dispelling the notion that deep

seabed habitats and communities are isolated from the water mass above that there is in fact ecological continuity throughout the water column

(Gage and Gordon, 1995). The existence of severe seabed currents, or

"benthic storms" has been detected during research undertaken at 2,400m

depth on the North Feni Ridge, west of Scotland. These submarine storms

are capable of remobilising sediments and dispersing them vertically in the water column as well as

horizontally across the seabed.

The bathyal regions of the Rockall Trough west of Scotland and north-west of Ireland, are thought to

be among the world's most biologically rich environments, due mainly to a large number of species of

microscopic mud-dwelling nematode worms and other invertebrates, most of which are new to

science. Contrary to the conventional view that marine biodiversity declines with depth, maximum

biodiversity occurs in these bathyal regions between 1,000-3,000m depths (Boucher and Lambshead,

1995).

In 1998, researchers from the University College Cork found cold-water coral reef structures some

350m high and several kilometres across at depths of up to 900m along the shelf edge west of

Ireland.

Also in 1998, an undersea feature previously unknown to science was

discovered during surveying of the deep seabed north of Shetland and west

of the Hebrides (UK waters). Hundreds of seabed mounds about 5m high and

100m across with tails several hundred metres long were found. Both

mounds and tails are characterised by a roughly 15-fold increase in the

density of xenophyophores giant deep ocean protozoa (single-celled

animals), subsequently identified as Syringammina fragilissima, which grows up to 20cm across. The

"Darwin Mounds" are at a depth of about 1,000m and are spread over 50 square kilometres of seabed

composed of deep foram sand sediments (the microscopic shells from trillions of dead phytoplankton),

in the northern Rockall Trough. Growing on the mounds are deep-water corals (Lophelia pertusa).


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Such discoveries, and the questions they raise, emphasise that present knowledge of deep-sea

ecology and physical processes is comparatively minimal.

The deep-sea comprises a habitat for many species of fish, including commercially important demersal

species such as roundnose grenadier, Atlantic orange roughy; pelagic oceanic (i.e. living in water

above the continental shelf edge and deep ocean) species such as albacore tuna and oceanic Atlanticredfishes (Sebastes sp.); and rays and sharks. Typically, little if anything is known about the

behaviour and ecology of deep-living fish species, such as orange roughy, and their populations.

Shelf area

Ocean circulation forces cold, nutrient rich water up the continental shelf slopes to the edge where it

mixes with warmer surface water. Ocean primary productivity is high at these areas known as

"upwellings". The nutrients and available sunlight support abundant growth of planktonic plant

organisms (phytoplankton), which in turn support both grazer and predatory planktonic animals

(zooplankton), then fish, squid, and higher predators in the food chain, including tunas, sharks,

marine turtles, seabirds, seals and cetaceans (porpoises, dolphins and

whales).

Small shrimp-like crustaceans, such as euphausiids, copepods and

amphipods, constitute the largest proportion of the zooplankton biomass;

many spend their entire life-cycle floating at the surface. Other zooplankton

organisms are the surface-dwelling (neustonic) eggs and larval stages of

fish and bottom-dwelling worms, crustaceans and molluscs, which release

millions of eggs to the water so that a few offspring may survive to disperse over a wide area before

returning to the seabed as adults.

When meteorological conditions are appropriate, a thin lipid (fat) rich surface film or microlayer forms

at the top of the water column. Marine surface films and microlayers, which may last for an extended

period of time, are an important habitat for both phytoplankton and zooplankton.

Two dominant warm water ocean currents influence Ireland's marine environment. The first is the

North Atlantic Drift (a continuation of the Gulf Stream that flows across open ocean from the

Caribbean region), which warms the western coastal waters of Ireland. It brings with it an unusual

faunal community including species such as the colonial hydrozoan Velella velella, also known as the

"by-the-wind-sailor", and giants such as the sunfish and marine turtles, including the leatherback and

loggerhead.

The second major influence is the warm water current that flows northwards along the European

continental shelf edge carrying with it a planktonic community that originates in the Mediterranean

Sea. This Lusitanian faunal community appears at the surface on the coasts of south, south-west and

west Ireland, and is represented by adult stage animals such as the crawfish, red deadman's fingers

and trumpet anemone.


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Away from the warming influences of these two currents, the cooler waters to the north of Ireland

support marine animals with an arctic-boreal distribution such as the stonecrab. While Ireland is at the

northern limit of certain marine species with a sub-equatorial distribution, it is likewise at the southern

limit of many sub-polar species.

To the east of Ireland, warm water enters the shallow semi-enclosed Irish Sea through the StGeorge's Channel between County Wexford and south Wales, while a colder northern current flows

south through the North Channel between Counties Antrim and Down and south-west Scotland. Where

the two currents meet along a zone of "frontal mixing" across the north Irish Sea (near the Isle of

Man), high densities of plankton are brought to the surface where they attract fish, including

important numbers of filter-feeding basking sharks - the second largest fish in the world.

Basking sharks are frequently seen in the Irish Sea and above the continental shelf off the south and

west coasts of Ireland. Though little is known about basking shark behaviour, it is thought that during

autumn and winter they move offshore to deeper water; in spring they move back inshore to feed on

the seasonal abundance of plankton in coastal waters, especially at frontal mixing zones. Females give

birth to live young; the litter size is unknown, except for one incident where a female gave birth to six

young. Basking sharks, while being long-lived, are slow to reach sexual maturity and hence their

reproduction rate is low. It is not known where around Ireland and Britain female basking sharks go to

give birth.

The average water depth of the Irish Sea is about 100-150m. The faunal communities of the seabed

reflect the range of bottom sediments, including widespread glacial deposits, and the degree of

exposure to benthic currents.

In general, seabed communities around Ireland's coasts remain poorly understood. There are

estimated to be more than 15,000 benthic species in the shelf seas around Britain, reflecting the widerange of environmental conditions around those coasts (DETR, 1998).

Several North-East Atlantic populations of commercially important fish species are present in Ireland's

shelf waters, either as residents or migrants. For example:

Atlantic cod is generally a demersal species (i.e. it lives and feeds at or near the seabed) thatoften migrates long distances to spawning and feeding grounds where it may become more

pelagic in habit (i.e. living nearer to the sea surface). Though mostly found within continental

shelf areas that are between 150-200m deep, Atlantic cod are widely distributed through a

variety of habitats, from the near-shore to well down the continental shelf to depths of over

600m. Atlantic cod move inshore to spawn in depths generally less than 50m.

Atlantic herring inhabit coastal pelagic and semi-pelagic waters (down to 200m) of thecontinental shelf. They have complex feeding and spawning migrations. Depending on race,

spawning takes place in coastal waters down to 200m.


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Atlantic mackerel is a semi-pelagic and mesodemersal species (i.e. it lives in mid-water) thatis most abundant in cold and temperate shelf areas. They over-winter in deeper waters but

move inshore in spring to spawn in coastal waters.

Blue whiting is a semi-pelagic species that feeds in the Norwegian Sea on plankton in thewater column at a depth below pelagic feeders. They migrate south along the shelf edge tospawn west of Scotland and off the west and northwest coast of Ireland.

Other commercially important fish occurring in Ireland's shelf waters include

demersal species allied to the cod such as haddock, white pollack and hake;

demersal flatfish such as halibut, plaice, sole, megrim and turbot; demersal

monkfish and sand eel; pelagic neritic (i.e. living in water above the

continental shelf) species such as Atlantic salmon; and rays (e.g. skate) and

sharks (e.g. spur dog and spotted dogfish).

Numerous other fish species such as wrasse, conger eel, flounder and sea bass are of importance to

the sea angling industry.

Populations of shrimps (prawns) and other crustaceans such as Nephrops (also called Dublin Bay

prawn, Norway lobster, or scampi), crawfish, lobster and crabs, as well as molluscs squid and

shellfish such as scallops, mussels and oysters are also of commercial importance in Irish waters.

Near-shore waters

Ireland's near-shore[2] habitats support rich and diverse communities of marine fauna and flora, and

often include unusual and rare species. For example, the region of Kilkieran Bay in County Galway is

renowned for its unique white beaches such as Coral Strand at Carraroe. These are formed from the

remains of an unattached calcareous algae (calcified seaweed) known as Lithothamnion, marl, or

simply "coral", which wash ashore during winter storms. Marl grows in the clear, warm and shallow

bay waters to form extensive beds on the sea floor.

The marl beds, like tropical coral reefs, provide shelter for many other marine animals, including

molluscs, sea cucumbers and sea urchins. Likewise, dense beds of horse mussels provide shelter for

an assemblage of other marine animals such as tubeworms, sea squirts, variegated scallops and sea

cucumbers.

Strangford Lough, a large sea inlet of great conservation value in County Down, is

especially important as a spawning area for fish, including sand eels, which spawn

in the sandbanks near the low-water mark. Sand eels are an essential component

of the marine ecosystem in many coastal waters around Ireland. They are predated

by a host of larger animals and are an important part of the diet of many seabirds

such as puffins, especially during the breeding season.
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Importance of the Ocean