Three-quarters of the world’s fish stocks are currently exploited to the maximum extent, if not in excess (FAO, 2000). This exploitation has had the following impacts: - A growing variety of fishery products are being exploited. Commercial fishermen are targeting progressively smaller species at lower levels of the food chain because the main predator species are being depleted. - Most of the world’s main fishing areas are close to full exploit...

It has been predicted that access to water will create conflict between countries. In Africa, central Asia, west Asia and the Americas, some countries are already arguing fiercely over access to rivers and inland seas, and confrontations could arise as water shortages grow (Gleick, 2000). Countries currently or potentially involved in international disputes over access to river water and aquifers include: - Turkey, Syria and Iraq (the Tigris and...

Although freshwater ecosystems such as rivers, lakes and wetlands occupy less than 2% of the earth’s total land surface, they provide a wide range of habitats for a significant proportion of the world’s plant and animal species. Many are yet to be discovered, but the number of freshwater species worldwide is estimated at between 9,000 and 25,000 (Cosgrove and Rijsberman, 2000). However, this number is rapidly decreasing due to human interference....

The Marine Species Population Index provides an assessment of the average changeover time in the populations of 217 species of marine mammals, birds, reptiles, and fish. The index represents the average value of six regional ocean indices. More pronounced declines are seen in the southern oceans, attributed to the fact that major losses and degradation of marine ecosystems in the industrialized world took place prior to 1970. Marine species are ...

There are two distinct regions in which coral reefs are primarily distributed: the Wider Caribbean (Atlantic Ocean) and the Indo-Pacific (from East Africa and the Red Sea to the Central Pacific Ocean). - The diversity of coral is far greater in the Indo-Pacific, particularly around Indonesia, the Philippines, and Papua New Guinea. Many other groups of marine fauna show similar patterns, with a much greater diversity in the Indo-Pacific region. ...

The availability of oxygen is one of the most important indicators of the condition of a water body, because dissolved oxygen, or DO, (the amount of oxygen dissolved in water) is necessary for most aquatic organisms, including fish and invertebrates. Some species have very defined lower limits of DO that they can tolerate. Increases in DO can indicate improvements in water quality, such as has occurred in many parts of the world in the last 30 ye...

'The over-exploitation and mismanagement of fisheries, particularly when combined with other man-made stresses, can lead to the collapse of regional fish faunas. In many countries, aquaculture is rapidly increasing in response to declining natural fisheries, often exacerbating the degradation of inland and coastal ecosystems through habitat alteration, pollution and the introduction of alien species' (Revenga et al., 1998). The Freshwater Specie...

The construction of large dams - defined as those with walls at least 15 metres high - has increased significantly over the past 50 years. The average height of new dams, estimated at 30-34 m from 1940-1990, increased to about 45 m in the 1990s, due largely to construction trends in Asia. The average area and volume of freshwater reservoirs have also steadily increased, rising to about 50 km2 between 1945 and1970, declining through the 1980s to 1...

Limited information is available on species diversity and the condition of coastal and marine ecosystems (Burke et al., 2001). There is growing evidence that many marine species are less widely distributed, and therefore more vulnerable to extinction, than previously thought (GESAMP, 2001a). The protection and sustainable use of marine resources and biodiversity are governed by several international conventions, including the Convention on Biolog...

Arctic sea-ice reductions have significant impacts on climate, wildlife and communities. The opening of open water across the Arctic ocean will have unknown consequences in terms of changes in water circulation and redistribution of species from the Atlantic and Pacific oceans. As sea ice coverage declines, albedo diminishes and more radiation is absorbed by the sea water, in a feed-back process that enhances warming and melting sea ice.

Change in the initial species richness in 2005 relative to 2001-2005 average (high-range climate change scenario). Studies predict species invasion will be profound in the Arctic and Southern Oceans. Among others these changes could result in a significant turnover of species of more than 60% of present biodiversity. This has the potential to disrupt a range of marine ecosystem services including food provisioning.

The Working for Water programme was launched in 1995 and is administered through the Department of Water Affairs and Forestry. The programme works in partnership with local communities which it provides with jobs, and also with government departments including the then Departments of Environmental Affairs and Tourism, Agriculture, and Trade and Industry, provincial departments of agriculture, conservation and environment, research foundations and...

Despite the widespread distribution and extent of alien invasive species in South Africa, actions to control such plants have had some good results. In the fight against invasive alien plant species, the Working for Water programme has used various methods including mechanical methods, chemical methods, biological control, and integrated control.

Alien plant species pose a major threat to South Africa’s native biodiversity. It is estimated that more than 9 000 plant species have been introduced so far. Of these, about 198 species are deemed invasive, covering 10 per cent of the country. Since the invasive plants grow by an estimated 5 per cent a year, their presence has dramatic effects on both native species and ecosystems as well as economic activities in the area. In particular, alien ...

South Africa is recognised as the third most megadiverse country in the world. The abundance of biodiversity found within its borders covers an estimated ten per cent of the world’s plant species, seven per cent of all bird, six per cent of all mammal, and five per cent of all reptile species found on the planet. Due to various causes ranging from unsustainable land use and farming practices, to invasion by alien species and climate change, So...

All great ape species predominantly live in tropical rainforests, which are among the most carbon-rich areas in the world. This overlap between the areas where great apes occur and carbon indicates that more potential synergies between great apes and carbon conservation exist.

Migration from the island of Nias to the West Batang Toru forests over the last two decades has been largely spontaneous. These settlers have opened up primary forests for agriculture and hunt many species of local wildlife, including orangutans. Currently at least eight Nias communities have been established inside the protected forest in the Batang Toru area, leading to the loss of more than 2,200 ha of orangutan forest habitat in specifically ...

If only the most important orangutan habitat is examined – i.e. forest below 1,000 m – for the 1985-2007 period, the rate of loss was even higher, at 28% and 49% for Aceh and North Sumatra respectively. When only the most species-rich forests (below 500 m) are considered, forest loss between 1985 and 2007 was 36% for Aceh and 61% for North Sumatra. For the carbon-rich peat swamp forests the loss was 33% for Aceh and 78% for North Sumatra.

Sumatran orangutan habitat overlaps 2 Provinces and 21 Districts, presenting many challenges for integrated development policies. 78% of the species’ present range lies within Aceh, and the remaining 22% in North Sumatra. A total of 13 districts in Aceh, and eight in North Sumatra, contain forests where wild Sumatran orangutans still occur.

Forests that support Sumatran orangutans also harbour high numbers of other animal and plant species, including some of the most emblematic megafauna species in the world, the Sumatran tiger (Panthera tigris sumatrae), Sumatran elephant (Elephas maximus sumatranus) and Sumatran rhinoceros (Dicerorhinus sumatrensis).