Issue 12: Loss of ecosystems or ecotones |
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Description |
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Ecological systems play a fundamental role in supporting life on Earth at all hierarchical scales. They are essential in global material cycles like the carbon and water cycles. Ecosystems produce renewable resources (food, fibre, timber, etc.) and ecological services. For example, fish are produced by a marine food web of plants, animals and microorganisms. Fish are part of the ecological system in which they are produced, and the interactions that produce and sustain fish are inherently complex. Ecological services are also generated by ecosystems. These include: · maintenance of the composition of the atmosphere · amelioration of climate variability · flood control and drinking water supply · waste assimilation · nutrient recycling · soil generation · crop pollination · pest regulation · food provision · biodiversity maintenance · and also maintenance of the scenery of the landscape, recreational sites, aesthetic and amenity values Natural systems at genetic, species, population and ecosystem levels all contribute in maintaining these functions and services. The increase of populations and economic activities in freshwater and coastal areas is leading to loss and modification of ecosystems. For example, 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 seafloor. 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 over harvesting 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. Reference UNEP Global Plan of Action for the Protection of the Marine Environment from Land Based Activities <enter> |
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GIWA definition |
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Loss refers to the complete destruction of all or part of an ecosystem or ecotone. An ecotone is a marginal ecosytem, usually depending upon the contact of land and water (e.g. Mangrove swamps, riparian floodplains, salt marshes etc.). For the purpose of GIWA methodology, the loss will be measured as a loss of one or more pre-defined habitats or key communities. |
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Environmental impacts |
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1. Loss of natural productivity 2. Loss of biodiversity 3. Loss of natural storm barriers 4. Loss of natural protection from erosion 5. Loss of carbon sinks and release of carbon to the atmosphere 6. Loss of migratory species using the habitat and altered migratory patterns 7. Impacts of estuarine system changes on adjacent coastal marine ecosystems 8. Loss of filtering water function |
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GIWA habitat classification scheme |
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To enter the GIWA water habitat classification scheme index for Issue 12: Loss of ecosystems or ecotones, please click here or from the hyperlink at the bottom of this page. The GIWA habitat classification scheme is divided into 2 categories: 1. Freshwater 2. Marine |