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 social, cultural 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 other resources. Scientific study helps us to understand why marine ecosystems are vital to our well-being, and how they are affected by human activities taking place on land, at sea and in the atmosphere.
It is now apparent that the oceans and seas are undergoing profound human-induced change and that the scale, intensity and speed of such forced transformations have increased tremendously in the past century as a consequence of growing human populations, higher levels of consumption and increasingly potent technologies.
Multiple interacting human activities and pressures pose an unprecedented threat to the stability of ocean and coastal ecosystems and the existence of species on a worldwide scale. Symptoms include:
By allowing the pressures on the marine environment to increase through sustained development, we jeopardise our own health, well-being and survival.
Human activities that create pressures and require integrated ecosystem-based management include:
Marine fisheries: unsustainable exploitation of fish stocks ("overfishing"), bycatch and discards, and dumping of offal and other wastes from boats, resulting in marine ecosystem imbalance and regime shifts; disturbance and modification of sensitive habitat types, such as ancient deep-sea coral beds damaged by trawl gear; and marine litter from vessels including loss of nets.
Marine aquaculture or mariculture: fish farm escapees interbreeding with wild fish causing genetic changes in wild populations; water quality issues due to faecal waste, excess feed and chemical treatments; placement of fish farm structures in the marine environment causing localised habitat modifications and spatial conflicts with other marine users.
Introduction and transfer of invasive non-indigenous (exotic or alien) species and genetically modified and disease-bearing organisms with potential to disrupt coastal ecosystems, including through discharge of ships' ballast water and sediments, transport of biofouling on vessel hulls, via marine aquaculture, and from use of bioremediation techniques for treating oil spills.
Maritime transport (merchant shipping, passenger vessels and other sea-going craft): exhaust (CO2, SOx and NOx) emissions; ship-to-sea discharges of hazardous substances; antifouling hull coatings; loss of fuel oil or hazardous cargo (including crude oil) as a result of accidents; undersea noise pollution and other disturbance to sensitive species, habitats and conservation areas.
Offshore oil and gas exploration, appraisal, production and further development activities: undersea noise pollution and disturbance from seismic surveying; habitat loss or degradation due to construction and placement of structures and dumping of drill cuttings; operational and accidental discharges of drilling fluid contaminated cuttings, produced water, oil, production chemicals and other hazardous substances; deposition of radioactive salts in pipelines; emissions of greenhouse and other gases and particulates including at-sea deposition of toxic polycyclic aromatic hydrocarbons (PAH) and nutrients (NOx); and spillage of oil as a result of accidents.
Contamination by hazardous substances (particularly those that are toxic, persistent and liable to bioaccumulate), including in the human food chain, and heavy metals via discharge, emission and loss from land-based industrial processes, agriculture, and commercial and domestic uses, and as a result of disturbance and redistribution of historic legacy deposits. Use of dispersant chemicals on oil spills. Linked to immune system disorders at higher marine trophic levels, i.e. in marine mammals, turtles, seabirds and predatory fishes such as tunas and sharks.
Human activities in the coastal margins, including development of port, harbour, marina and other infrastructure; urbanisation; coastal protection and other coastal engineering works; land reclamation; dredging and dumping of spoil; marine aggregates (sand and gravel) and maërl extraction; and tourism and recreation. Resulting in loss or degradation of natural habitat (e.g. sand dune systems, salt marsh, reed beds and other coastal wetlands) through physical, chemical or biological modifications, or through disturbance to wildlife feeding, breeding or resting sites.
Construction and placement of installations and structures in the marine environment, including renewable energy generating station developments such as offshore wind turbine installations and wind farms, tidal barrages and wave power installations; artificial reefs for fish; electrical and telecommunications cables; and pipelines including those related to offshore oil and gas transfer activities.
Chronic oil pollution from both land-based (riverine input and urban wastewater outfalls) and offshore sources including offshore oil and gas platforms, and illegal vessel discharges of oil and oily water at sea from washing cargo and fuel tanks, and flushing bilges or ballast water tanks.
Nuclear waste, fuel, weapons and other material processing, handling and storage: deliberate and accidental atmospheric emissions and liquid discharges to sea of radionuclides from processing plants, nuclear power stations, research establishments, nuclear submarines and other naval-military sources, resulting in radioactive hotspots in marine sediments, coastal groundwaters and in precipitation, with potential to enter the food chain.
Eutrophication caused by excessive inputs of nutrients (nitrogen and phosphorous) from multiple sources including agriculture, industry and domestic, as well as from atmospheric deposition of NOx from ship exhaust emissions, which may give rise to (increased) algal blooms and problems of algal toxins and oxygen depletion in benthic waters due to decomposing algae.
Pathogenic microbiological pollution from urban wastewater, including untreated or partially treated sewage, and agricultural slurry discharges.
Contamination of coastal waters and beaches with litter from fishing vessels and merchant shipping, and coastal tourism and recreational activities.
Climate change due to increasing concentrations of anthropogenic greenhouse gases such as carbon dioxide (CO2) in the atmosphere, mainly as a result of fossil fuels combustion, but also as a result of major land-use changes such as deforestation, land "improvement" and cattle ranching, and complex ecological system feedback mechanisms.
Global climate change is likely to have far-reaching consequences for marine ecosystems, habitats and species through changes in temperature, wind climate, water circulation, relative sea level height, surface waves, bottom topography, storm surges; and in changes in precipitation patterns, freshwater run-off, flooding risk, erosion, and wetland loss with downstream effects (e.g. changes in salinity, nutrient levels, turbidity and mobilisation of hazardous substances from contaminated land and microbiological pollution from sewers and septic tanks) on marine and coastal morphology, ecosystem structure and function, biological productivity, and human activities and settlement patterns along the coast.
Management systems to control and reduce these pressures and their environmental impact do exist. In general, however, they have been developed on a sectoral basis resulting in a patchwork of legislation, policies, programmes and management plans at local, national, EU and international level.
There is, however, justified hope that the move towards a more holistic and integrative management approach might be able to work around some of these obstacles. The key is to develop linkage between the pieces and place them in an overarching, integrated management framework according to ecosystem principles.
Nowadays, it is internationally accepted that an ecosystem-based approach should be taken to policy-making, environmental assessment and integrated management, in which each sector should consider the positive or negative impacts on other sectors and marine and coastal ecosystems in accordance with the precautionary principle. This view was codified in the overarching international legal instrument the 1992 Convention on Biological Diversity.
For more about integrated ocean and coastal management and the ecosystem-based approach, see Policy and Governance.