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Physical alterations

Physical alterations in the coastal zone

The increase of populations and economic activities in coastal areas is leading to an expansion of construction and alterations to coastal areas and waters. Excavation, oil and gas exploration and exploitation, mining, such as sand and aggregate extraction, the building of ports and marinas and building of coastal defences and other activities linked to urban expansion are giving rise to alterations of coral reefs, shorelands, beachfronts and the seaf loor. Important habitats are being destroyed. Wetlands are being transformed into agricultural lands and through coastal development.

Tourism, unrestricted and uncontrolled aquaculture, clearance of mangroves and destructive fishing practices, such as the use of dynamite and chemicals, are also causing the physical destruction of important habitats. The introduction of alien species can also have serious effects upon marine ecosystem integrity. Spawning grounds, nurseries and feeding grounds of major living marine resources of crucial importance to world food security are being destroyed. This destruction of habitat exacerbates overharvesting of these living marine resources leading to a growing risk that they are being depleted. This is an increasing threat to the food security of coastal populations, in particular in developing countries.

The damming of river systems can result in upstream sedimentation, possible changes in estuarine conditions and interference with fish migration. These adversely affect biological diversity and biological productivity. The practice of saltwinning from saltpan construction in coastal areas can also affect salt concentration levels and biological diversity.