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Satellite image of the Turucui dam and associated deforestation in Brazil. (Photo courtesy of DigitalEarth)
THREATS TO TROPICAL RIVERS AND LAKES
Tropical rainforest waters are highly threatened today by hydroelectric projects, erosion from deforestation, overfishing,
and poisoning from oil and chemical spills. The effects from the degradation of these waters are widespread, inflicting
damage on the global economy, the environment, and local peoples.
Balbina dam outside Manaus, Brazil
The Balbina dam flooded some 2,400 square kilometers (920 square miles) of rainforest when it was completed. Phillip Fearnside, a leading expert on the Amazon, calculated that in the first three years of its existence, the Balbina Reservoir emitted 23,750,000 tons of carbon dioxide and 140,000 tons of methane, both potent greenhouse gases which contribute to global climate change.
Increasing demands for energy are putting the world's rivers at risk.
Hydroelectric projects are responsible for flooding vast areas of rainforest. The decay of forest wood adds more
greenhouse gases to the atmosphere contributing to global warming. This flooding means that terrestrial species,
including humans, must migrate to new areas usually leading to more deforestation. Fish species adapted to the
riverine environment must adapt to lake conditions or perish. Dams disrupt the migration of species which move
up- or downriver to spawn.
Erosion is a well-known result of deforestation with serious consequences for river commerce and river life. Sediments
build up creating sandbars and shallows and interfering with river transportation. Similarly, sediment build-up reduces
the effectiveness of existing hydroelectric projects. Erosion and the resulting decline in water clarity causes
downstream mayhem for offshore coral reefs. River inhabitants also suffer due to the reduced water clarity. Species
that rely primarily on sight decline the most, while the increased amount of suspended particles interferes with
fish gills. Erosion inhibits plant growth and hinders the development of fish eggs.
Overfishing is a problem that plagues the world's oceans (35-60 percent are overfished worldwide [overfishing news]) and freshwater habitats.
Regional declines in catch have been reported throughout the Amazon. The loss of certain species responsible for
seed dispersal will have a negative effect on the renewal of the rainforest.
Poisoning from spills and pollution from industrial processes mining, and sewage continue to reduce the diversity
of rainforest waters, in addition to affecting human populations. The much publicized spill on the Essequibo river,
along with the continued spilling of oil in Peru and Ecuador, has had an impact of river life.
Blackout in Brazil: Hydropower and Our Climate Conundrum
(11/19/2009) It’s everyone’s worst nightmare: being caught in an underground subway in the midst of a power outage. Yet, that is exactly what happened recently when Brazilian commuters in the city of São Paulo were trapped inside trains and literally had to be pulled out of subway cars. In addition to sparking problems in public transport, the blackout or apagão led to hospital emergencies and the shutting down of several airports. In all the power outage darkened approximately half of the South American nation, affecting sixty million people.
Will Brazil's blackout drive a new push for more rainforest dams?
(11/12/2009) The power outage that affected nearly a third of Brazil's population Tuesday could be used by development interests to justify a renewed push for hydroelectric dams in the Amazon rainforest.
Kihansi spray toad goes extinct in the wild
(11/04/2009) This year's IUCN Red List has updated its assessment of the Kihansi spray toad, moving the species from Critically Endangered to Extinct in the Wild. With that another amphibian species has been lost to a combination of habitat loss and the devastating amphibian disease, the chytrid fungus. The Kihansi spray toad Nectophrynoides asperginis, which still survives in a number of zoos in the United States, had lived on just two hectares along the Kihansi gorge in Tanzania. The toad was specially adapted to the spray region of the Kihansi waterfall, which kept its small environment at a constant temperature and humidity.
The Yangtze River may have lost another inhabitant: the Chinese paddlefish
(10/22/2009) In December of 2006 it was announced that the Yangtze River dolphin, commonly known as the baiji, had succumbed to extinction. The dolphin had survived on earth for 20 million years, but the species couldn't survive the combined onslaught of pollution, habitat loss, boat traffic, entanglement in fishing hooks, death from illegal electric fishing, and the construction of several massive dams. Now, another flagship species of the Yangtze River appears to have vanished.
