Physical Alterations and Destruction of Habitats (PADH)
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MiningThreatsGeneral Resources Unregulated mining activities may cause significant and serious damages to seabeds and their ecosystems, to fisheries and to nearby coastlines. It may also give rise to conflicts with other legitimate uses of the sea, e.g., fisheries. Mining of sand, gravel and other minerals from the seabed can have significant physical and biological impacts on the marine and coastal environment. The importance and extent of the effects depend on a wide range of factors, including the location of the exploitation area, the method and rate of extraction, the design of machinery, as well as the nature of the surface of the sea bottom, the sediments, the coastal processes, and the sensitivity of habitats and species. The benefits of coastal and offshore mining - sand and gravel extraction and mining of various minerals - should be carefully assessed against the potential negative impacts of mining activities. Traditionally, the main marine areas considered suitable for mining resources from the seabed have been restricted to areas near the coast and at shallow depths, i.e., less than approximately 80 meters. New techniques, many of which have been developed within the offshore oil and gas industry, are now allowing the industry to expand into deeper waters. For examples, diamonds are now mined at depths up to 120 meters off the Namibian coast. Marine sand and gravel, as well as the minerals of interest found on or in the seabed, are limited, non-renewable resources. According to the International Council of the Exploration of the Sea (ICES), even though resource inventories made indicate when there are extensive supplies of some types of marine sands, there seems to be more limited resources of gravel suitable to meet demands according to specifications and for beach nourishment. Thus, minerals should be used as efficiently as possible, and reused when possible, to ensure that future demands can be met. The quantities of sand and gravel presently being exploited are very large. For example, in the Northeast Atlantic alone, annual extraction of sand and gravel has been recorded to an average of 40 million cubic metres during the 1990's.
Resources
Anthropogenic threats As pointed out in the GPA PADH Key Principles on Coastal Mining Development Mining ”coastal mining is diverse. It is undertaken at varying levels of intensity from large-scale enterprises to small-scale and artisinal mining and employ a variety of methods to mine a variety of minerals. The sector can have far reaching environmental and social impacts and invariably requires the dedicated use of coastal land for which there is obvious competing community demands. Hence an integrated approach is required to manage the sector and seek a balance between ecological integrity, social equity and economic development”. The importance and magnitude of the potential negative environmental effects depend on a number of factors. including the location of the exploitation area, the method and rate of extraction, the design of machinery, as well as the nature of the surface of the sea bottom, the sediments, the coastal processes, and the sensitivity of habitats and species, fisheries and other ongoing uses in the area concerned. This wide range of potential environmental effects also have socio-economic impacts on local communities and individuals depending on the biological resources, as well as on the ecological services provided by undisturbed seabeds and living coral reefs. Som examples: Effects on fisheries
Effects on local communities
Anthropogenic Resources
Ecological threats In mining of sand, gravel and minerals on the seabed, dredge mining is likely to have the largest impact. Dredges will dig up the ocean floor, thereby damaging habitats and killing species of fish, invertebrates and algae. Much the same will occur when dredges are used to keep harbours and channels open for shipping. If an area is subject to extensive seabed mining, this may destroy the bottom ecosystems on the seabed completely. As underlined by the Helsinki Commission (HELCOM), bottom-living organisms are the feeding base for waterfowl and fish. Temporary destruction of the communities of bottom organisms, and/or permanent alteration of the composition of these communities as a result of mining may, thus, have an impact on the feeding conditions for species higher up in the food web. Fish stocks may be seriously affected by the mining process, particularly if the mining takes place in an area that constitutes an important spawning or nursing ground for fish. Another effect on fish and filter-feeding organisms may occur when fine sediments stirred up during mining redeposit on the seabed. This may result in the smothering of fish eggs on spawning grounds, such as herring and sand eel, and the suffocation of filter-feeders like mussels. In addition, shellfish, e.g., lobsters, may lose their habitats through silting of the crevices in which they live. Also, fishing may be hindered if the mining results in an uneven bottom topography. Bottom trawls and other fishing gear may be destroyed. Other potential effects of mining include changes in the hydrographical conditions within an area and in areas adjacent to the area mined. Alteration of bottom topography by dredging operations may cause changes in the hydrographical conditions, thereby affecting the strength of currents, water exchange and/or sediment transport. A localized decrease in current strength may result in increased deposition of finer sediments and may subsequently lead to oxygen depletion. Possible effects on coastal erosion due to alteration of wave and current patterns are another potentially serious effect, particularly if mining is undertaken in shallow water areas. Impacts on coastal protection can be extensive, either by interference with the supply of sand and gravel to the beach or by reducing offshore wave protection and thereby changing the wave energy and/or direction reaching the coast. Offshore mining can also cause problems with sediment plumes generated in the mining process. In the process of diamond mining, sediments are brought to the surface (generally to a large ship), where workers and machinery separate the diamonds from the sand and gravel. Immediately after the diamonds have been separated from the sediments, the sediments are returned to the ocean bottom. Once the sediments are discharged into the water they may make the water less transparent, thus reducing photosynthesis of phytoplankton and/or bottom living macro algae. Another potential risk is that the processes will cause heavy metals or other toxic substances to be released into the water column. These may subsequently accumulate in the food chain causing further impacts on marine organisms. Live coral pieces are removed from reefs, to be crushed and used as bricks or road-fill, while sand and limestone are used for manufacturing cement for the construction industry. Corals are also removed from their habitats to be sold as souvenirs to tourists and export companies who do not know or do not care about the longer-term damage done. Mining coral removes habitat of a large number marine species, and weakens coastal storm defenses. Rebuilding coral takes a long time because colonies of tiny coral animals grow very slowly. As a result mined or dredged areas take a very long time to recover.
Ecological Resources
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