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Lake Balbina, a man-made reservoir created to supply hydroelectric power to the city of Manaus in Brazil.
(Photo courtesy of Jacques Descloitres, MODIS Rapid Response Team, NASA/GSFC)
Large hydroelectric projects, funded by international aid and development organizations like the World Bank, have led to widespread forest loss. Besides inundating large tracts of rainforest (dams in the Amazon are generally ecologically inefficient because large tracts of forest are flooded due to the flatness of the basin) and killing off local wildlife, the dams have the effect of destroying aquatic habitats and affecting fish populations, displacing indigenous peoples, and adding carbon to the atmosphere (as the submerged wood rots). On top of the ecological damage, several projects have silted up from the erosion resulting from deforestation, rendering the dams inefficient. The reduced water flow downstream disturbs riverbeds and affects floodplain farmers who rely on seasonal floods for nutrients to enrich the soil and kill pests. Thus they may turn to pesticides and artificial fertilizers which have their own negative environmental effects. Deltas experience a greater influx of salt water, affecting coastal ecosystems essential to fisheries. Hydroelectric projects are also of concern from a health standpoint because they provide opportunities for the spread of disease-carrying organisms including snails (schistosomiasis/bilharzia) and mosquitoes (dengue fever, yellow fever, malaria).
Although "mega-projects" in Latin America are today facing more opposition and being reexamined by the sponsoring parties, hydroelectric projects in Asia are skyrocketing. On the Mekong alone, one of tropical Asia's biologically richest rivers, some 17 dams are planned, while 54 hydroelectric projects are in the works for the Mekong Basin.
Acid rain, expected to increase dramatically in the tropics in the coming years, also takes its toll on tropical forests. 15 percent of the world's remaining tropical forests may soon be affected by acid rain. Similarly, a vast area of forest will be adversely affected by UV-B radiation, should the ozone hole continue to expand.
The dumping of trash and human waste into tributaries from overcrowded cities has resulted in serious pollution in many tropical countries. In some areas, rivers are no longer safe for human use, while plant and animal life suffers.
Fertilizers and pesticides used in agricultural areas adjacent to forests can take a toll on rainforest wildlife, including critical pollinators and seed dispersers. Since chemicals tend to accumulate up the food chain, top predators are likely to be most affected by toxic substances used in pesticides and fertilizers. Chemicals also wash into local waterways, affecting aquatic life.
Centrally planned urban experiments has resulted in tremendous forest loss in parts of the world. Indonesia's massive Transmigration Program moved some 730,000 families—more than six million people—to the outer islands of Irian Jaya, Borneo, Sumatra, and Sulawesi in an effort to reduce population pressures on the crowded central islands of Java and Bali. The program was generally seen as a failure since many colonists failed to establish successful farms in the hinterlands while large areas of primary forest were cleared. Today some of the worst fires in Indonesia occurs on these once-forested lands.
While they are not responsible for deforestation, hunting and poaching cause damage to the rainforest ecosystem by removing species key to the system's functioning. The loss of a certain single species can mean extinction for many others.
The wildlife harvest takes a staggering number of animals: every year in the Brazilian Amazon alone, where 9.6 to 23.5 million mammals, birds, and reptiles are harvested. The annual harvest in the tropical forests of Africa may be 6-12 times that amount, since illegal poaching in Africa is rampant to provide meat for poor rural and urban dwellers.
In Asia, tiger populations have been dramatically reduced due to widespread habitat loss and Chinese demand for traditional medicinal products made from tiger parts. Endangered Sumatran elephants are increasingly poached for their ivory and could go extinct within 50 years at present hunting rates. In Indonesia, where there is a thriving black market for endangered wildlife, orangutans are suffering from both habitat loss and the illegal trapping of baby orangutans for the pet trade. Typically, mother orangutans are killed since they refuse to abandon their young.
In Brazil, Colombia, Nigeria, Madagascar, and other countries, the collection of wild animals for the pet trade takes its toll on local animal populations. Although such collection can be done in a sustainable manner, it rarely is. Reptiles are the fourth biggest commodity after drugs, diamonds, and weapons in the world smuggling trade, but losses are quite high: less than 10 percent of all animals exported illegally make it alive to their final destination—usually a small, dirty aquarium.
While not directly responsible for deforestation, the introduction of foreign plants and animals can cause severe damage to rainforests, especially in delicate ecosystems like islands. These feral species bring new diseases and compete with local species.
The bird life of Guam and Hawaii has suffered from the introduction of alien species. In the case of Guam the culprit was a snake, while in Hawaii the mosquito and domestic chickens were responsible for the decline of native birds. Since the arrival of the Polynesians, at least 62 endemic bird species have disappeared. It is even more startling that Hawaii has more alien plant species than native ones. Alien weeds can choke out endemic plants, especially under disturbed forest conditions like agricultural clearing.
Additionally, alien species can wipe out endemic keystone species that play an important role in the ecosystem, like pollinating certain tree species. The elimination of such an endemic species can spell the end for the tree species and a host of other dependent plant and animal species.
Oil palm workers still below poverty line, despite Minister's statements
(11/19/2009) On October 19th, Plantation Industries and Commodities Minister Tan Sri Bernard Dompok told parliament that oil palm harvesters and rubber tappers are living above Malaysia's national poverty line, according to a story in the Malaysian Insider. But now representatives of the workers are saying Dompok lied.
Pygmy hippo shot and killed in…Australia
(11/17/2009) Hunters going after pigs in Australia's Northwest Territories got a big surprise when they shot an animal they mistook for a pig, only to find out it was a pygmy hippopotamus, reports the Northwest Territory News.
ICCAT fails to protect critically endangered tuna—again
(11/15/2009) The International Commissions for the Conservation of Atlantic Tuna (ICCAT) ignored the advice of its scientists to end fishing of the Atlantic bluefin tuna. Instead ICAAT set a quota of 13,500 tons of fish. This is not the first time ICCAT has flouted its own researchers' advice: it has repeatedly set quotas well-above its researchers' recommendations.
DNA uncovers nearly extinct Siamese crocodiles in captivity
(11/15/2009) The Critically Endangered Siamese crocodile, once believed to be extinct in the wild, received some uplifting news this week. DNA testing of 69 rescued crocodiles at Phnom Tama Wildlife Rescue Center (PTWRC) in Cambodia found 35 purebred Siamese crocodiles.
Hunting across Southeast Asia weakens forests' survival, An interview with Richard Corlett
(11/08/2009) A large flying fox eats a fruit ingesting its seeds. Flying over the tropical forests it eventually deposits the seeds at the base of another tree far from the first. One of these seeds takes root, sprouts, and in thirty years time a new tree waits for another flying fox to spread its speed. In the Southeast Asian tropics an astounding 80 percent of seeds are spread not by wind, but by animals: birds, bats, rodents, even elephants. But in a region where animals of all shapes and sizes are being wiped out by uncontrolled hunting and poaching—what will the forests of the future look like? This is the question that has long occupied Richard Corlett, professor of biological science at the National University of Singapore.
