Gambia River

584 Gambia River Preservation As part of the broader Senegambia Catchment Because of their isolation and relatively recent dis- area, the Gambia River is an important ecosystem covery, the Galápagos have escaped the destruc- for biological diversity, though it has few endemic tion so often wreaked on oceanic islands. Cur- species (those found nowhere else on Earth) in rently, the biggest threats to the archipelago include its own waters. The river supports a range of eco- introduced species, loss of native biodiversity, and nomic activities from agriculture to fishing, hunt- human visitors. For this reason, the Ecuadorean ing, and transportation. It also shows promise for government has declared all the islands, except potential hydroelectric power. Like many of the areas already colonized, to be a national park, man- world’s aquatic and coastal systems, it is under aged in conjunction with the not-for-profit Charles direct threat from these anthropogenic factors. Darwin Foundation and Research Station. Mangroves, Salt Marsh, Wetlands Melanie L. Truan The estuarine and freshwater zones, which are largely a function of the reach of the tide and salt Further Reading water from the sea, create different communities Fitter, Julian, Daniel Fitter, and David Hosking. of flora and fauna. At its mouth, the Gambia is Wildlife of the Galápagos. Princeton, NJ: Princeton an 8-mile-wide (14-kilometer-wide) permanently University Press, 2000. flooded ria, or funnel-shaped, estuary formed Jackson, Michael H. Galápagos: A Natural History. from the submergence of the lower portion of the Calgary, Canada: University of Calgary Press, 1993. river valley. This estuary is a matrix of mangrove Kricher, John. Galápagos: A Natural History. swamps and creeks with riverside mudflats on ele- Princeton, NJ: Princeton University Press, 2006. vated ground formed from silt deposition. McMullen, Conley K. Flowering Plants of the The river narrows as it travels further inland, Galápagos. Ithaca, NY: Comstock Publishing though it remains about half a mile (one kilome- Associates, 1999. ter) wide, even 124 miles (200 kilometers) from the mouth. As the influence of the tide wanes, so does the level of flooding. The middle section of the river is only seasonally flooded, and the early stages of the river in the Fouta Djallon and south- Gambia River eastern Senegal—before the Gambia meets with any of its important tributaries—do not experi- Category: Inland Aquatic Biomes. ence any flooding. Geographic Location: West Africa. The basin of the Gambia River contains about Summary: The last remaining undammed river in 1,500 species of plants, 80 species of mammals, West Africa is an important reserve of biological 330 species of birds, 26 species of reptiles, and diversity and support for human well-being, but 150 species of freshwater fish. This diversity is threatened by human activities. results from the broad range of habitats including mangroves, freshwater swamps, salt mudflats, The Gambia River winds over 700 miles (1,130 and Sudanian-Guinean riverine forest. Though kilometers) from the Fouta Djallon highlands the Gambia is important for biodiversity, it is not of northern Guinea through southeastern Sen- unique from other river ecosystems in the area. It egal and The Gambia into the Atlantic Ocean. It possesses only a few endemic species. Most spe- is one of the largest rivers in West Africa and is cies are held in common with the Senegal, Baf- composed of two distinct habitat types: estuary at ing, and Faleme rivers and are known together the mouth and freshwater further upstream. Each as the Senegal-Gambia Catchment, or the Sen- of these supports a collection of flooded areas, egambia Catchment. Thus the Gambia River swamps, mudflats, and riverine forests. ecosystem is part of the broader Sudan-Guinean Gambia River 585 Savanna biome, and shares several species from Human Interaction the Guinea-Congo Forest biome and the Sahelian The importance of the Gambia River to human biome as well. communities is apparent from the names of the The mangroves and wetlands of the Gambia five administrative divisions of The Gambia: West- River reach 62 miles (100 kilometers) inland from ern, North Bank, Lower River, Central River, and the Atlantic and comprise one of the 200 most bio- Upper River. Many Gambians outside of the capi- logically valuable ecoregions of the Earth, as listed tal depend directly on agriculture and fishing for by the World Wildlife Fund. The river supports their wellbeing. Wood is the most common fuel nearly 111,000 acres (45,000 hectares) of man- source and comes from the riverbanks and flood- grove swamp dominated by trees such as Avicen- plain. These economic activities both depend on nia africana, Sesuvium portulacastrum, and Rhi- and severely impact the health of the river. zophora spp. Much of this area is covered with salt Nearly one-third of The Gambia has been con- marsh herbs and halophytic (salt-loving) grasses. verted to arable land dedicated to the production The mangroves support a diverse community of of rice, maize, groundnuts, millet, and sorghum. avifauna, both as breeding and wintering grounds. Similar land transformations have occurred in More than 560 bird species are found here, southeastern Senegal and are beginning in the including many migratory species arriving from mountainous Fouta Djallon of northern Guinea. Europe each winter who find refuge among the These transformations began centuries ago. Flood mangroves. The yellow-billed Stork Mycteria( ibis) rice cultivation has been the dominant land use on and African sacred ibis (Threskomis aethiopicus) the banks of the Gambia River for recorded his- can be spotted along the Gambia’s banks, along tory. The system of flood rice cultivation used in with the long crested eagle (Lophaetus occipitalis), the American south was a direct application of pelicans, and others birds that find food and shel- the system used along the banks of the Gambia; ter in the area. Owls such as the African scops owl evidence suggests that American slave owners and (Otus senegalensis) may also be found in this area. traders targeted slaves of particular ethnic groups Small-bodied mammals, such as the spotted- because of their experience in rice cultivation necked otter and greater cane rat, and larger bod- along the Gambia’s banks. ied mammals such as duikers, crocodiles, hippo- In addition to its role in cultivation, the river potamuses, and the vulnerable African manatee and its tributaries are fished from source to mouth. call this area home. Prawn is caught in the estuary, while fish are con- As the influence of the Atlantic tide and salt- sumed over the river’s entire course. Fish popula- water wanes, the Rhizophora mangroves thin and tions in the river remain relatively healthy. Hunting transition into a collection of freshwater swamps, for wildfowl and mammals of all sizes is common in salt flats, and seasonally flooded grasses, trees, the riverine wetlands. Crocodiles, African manatee, and agriculture. The freshwater swamps are and hippopotamuses have been hunted nearly to dominated by Phragmites karka grasses and are the point of local extinction in The Gambia, though habitat for many species of wintering birds. The hippopotamuses can be found in southeastern Sen- swamps create a breeding ground for mosquitoes egal, where human populations are less dense. and tsetse flies, which are vectors for malaria and Though the Gambia River remains the last sleeping sickness, respectively. The most efficient major undammed river in West Africa, there have malarial vector in sub-Saharan Africa and host been recent efforts to build a hydroelectric dam to the most deadly malarial parasite is Anopheles on the border between Senegal and Guinea, in gambiae, named for the region in which it is com- the region of Kedougou, Senegal. So far the gov- mon. Native fish diversity and abundance is an ernments of The Gambia, Guinea, Senegal, and important control on mosquito populations and Guinea Bissau have raised $700 million through provides a key ecosystem service by regulating the the African Development Bank for construction. malaria vector. The dam has potential to produce 400 gigawatt 586 Ganges River hours and would connect to power networks in all Ganges River four countries, though most of the power would go to Guinea and Senegal. Category: Inland Aquatic Biomes. On the negative side, the dam is expected to Geographic Location: Asia. impact the sedimentary balance in the river and Summary: The lifeline of India, the Ganges River estuary as well as modify the salt front. It will also supports massive and diverse habitats but is influence water quality, deplete mangroves, and threatened by climate change and pollution. generally lead to habitat loss and changes in the populations of some species. These concerns have The national river of India, the Ganges, originates led several conservation groups to begin plan- at Gaumukh as a stream called Bhagirathi, in the ning for monitoring ecosystem impacts of dam Gangotri glacier in the Himalayan Mountains at construction. As a potential source of electricity an altitude of 13,451 feet (4,100 meters) above as well as an important contributor of biodiversity mean sea level. The first town in the course of the and other ecosystem services, the Gambia River is Ganges, Gangotri, is 14 miles (23 kilometers) from a frontier for the management of ecosystems for its source of origin. The main stream of the river both environmental and human well-being. flows through the Himalayas until another two One effect of adding this dam to the Gambia streams—the Mandakini and the Alaknanda— River—the modification of the salt front—will likely join it at Devprayag, the point of confluence. The be exacerbated by global warming. With higher river is also known as Ganga Ma, Mother Ganges, average temperatures and projected lower annual and may be called Ganges or Ganga.

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