The Global 200 : a representation Approach to Conserving the Earth’s Distinctive Ecoregions
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Large River HeadwatersLarge River Headwaters represent the lower order tributaries to many of Earth’s most impressive rivers. Headwater areas are generally characterized by very different physical conditions when compared to the lower reaches of the system. For example, these regions generally have much smaller floodplains, have higher gradients, and are less productive. Species in these regions are well adapted to these conditions. They may be reliant on nutrient inputs from surrounding terrestrial systems, and these inputs may influence aquatic insect diversity. Afrotropical
ongo River Basin Piedmont Rivers and Streams [150] – Angola, Cameroon, Central African Republic, Democratic Republic of Congo, Gabon, Republic of Congo, Sudan Geographic Location: Central Africa Biodiversity Features: The Congo basin has the richest freshwater fish fauna of any African river, with 690 described fish species, of which 80% may be endemic. The main stem Congo River contains pockets of endemism along its sweep from the center of the continent to the coast. The localized distributions of many rivulin (Alestiidae) and snoutfish (Mormyridae) species in forest streams make the species naturally rare. piedmont streams displayING high endemism and beta diversity, FAUNA IS poorly known but likely very DISTINCTIVE Selected Species: The staggering diversity of fish in this ecoregion includes, among other endemic taxa, members of the nocturnal, electric Mormyridae; catfish of the Mochokidae, Bagridae, and Clariidae families; characoids; and cichlids (Cichlidae). The ecoregion is also home to the endemic aquatic genet (Osbornictis piscivora), giant otter shrew (Micropotamogale lamottei), and Ruwenzori otter shrew (Mesopotamogale ruwenzorii). General Threats: Several growing urban centers in the Congo basin are causing an increase in untreated sewage and other sources of pollution that could negatively affect downstream freshwater systems. Local pulses of sedimentation also occur near logging operations. A few industrial-scale mining operations exist in the Congo and likely affect localized areas. NearcticM ississippi Piedmont Rivers and Streams [151] – United States Geographic Location: Eastern North America Biodiversity Features: This ecoregion arguably encompasses the richest temperate freshwater ecosystems in the world, as measured by the hundreds of highly localized endemic species that have evolved in ancient river systems. Tennessee's Clinch River alone, for example, has 40 species of coexisting unionid mussels (20 other species have already been eliminated). Any relatively intact stream in this region supports more mussels than all of Australia and Europe combined. CONTAINS SOME OF THE RICHEST TEMPERATE FRESHWATER ECOSYSTEMS IN THE WORLD, WITH NUMEROUS regional and local ENDEMICS Selected Species: Among the numerous species of imperiled endemic mussels are dromedary pearlymussel (Dromus dromas), birdwing pearlymussel (Lemiox rimosus), and oyster mussel (Epioblasma capsaeformis). Imperiled endemic fishes include slackwater darter (Etheostoma boschungi), duskytail darter (E. percnurum), palezone shiner (Notropis albizonatus), smoky madtom (Noturus baileyi), and paddlefish (Polydon spathula). This ecoregion is also home to numerous endemic salamanders, including the West Virginia spring salamander (Gyrinophilus subterraneus), imitator salamander (Desmognathus imitator), shovelnose salamander (Leurognathus marmoratus), Tennessee cave salamander (Gyrinophilus palleucus), and streamside salamander (Ambyostoma barbouri). The Nashville crayfish (Orconectes shoupi) is endemic to this ecoregion as well. General Threats: Hydroelectric projects, channelization, water withdrawals, and pollution threaten the ecoregion. The Tennessee River system has more than 50 major dams, with many remaining freshwater species restricted to small segments of unaltered tributaries. Introduction of the nonnative zebra mussel (Dreissena polymorpha) and other exotics threatens native species. NeotropicalU pper Amazon Rivers and Streams [152] –Bolivia, Brazil, Colombia, Ecuador, French Guiana (France), Guyana, Peru, Suriname, Venezuela Geographic Location: Northwest and North-central South America Biodiversity Features:The Amazon River has over 1000 tributaries; those originating in the Andes on the western perimeter of the basin, and in the Guiana Highlands to the north of the Amazon River, comprise the major aquatic habitats of this ecoregion. Tributaries arising in the Andes are sediment-rich and appear muddy, whereas those formed in the Guiana Highlands in the north tend to be nutrient-poor blackwater rivers. The entire Amazon region has more than 1,300 described fish species, a number that will grow as more investigations are made, particularly in the poorly known headwaters. Piedmont regions rather than lowland central basins are believed to have the most pronounced levels of endemism and may exhibit high levels of beta diversity. Along with the Guayanan highlands freshwater ecoregion, the most species rich freshwater ecosystem on earth Selected Species: The Amazon’s piedmont streams have not been well investigated, but it is known that they harbor an incredible array of aquatic species, particularly fish. For example, over five hundred species are known from the Napo River, just one of the rivers in this ecoregion. Fish groups with high numbers of species represented include characins (e.g., tetras, piranhas, pacus), catfishes (e.g., doradids, loricariids, pimelodids), gymnotoids (“electric eels”), osteoglossids (relic “bony-tongues), and cichlids. Other aquatic taxa are expected to show high levels of diversity as well. General Threats: Deforestation of headwater catchments for logging and conversion to agriculture and pasture is a potentially serious problem, leading to erosion and altered hydrologic regimes. There is concern that deforestation will reduce the region’s evapotranspiration and alter the Amazon’s hydrologic cycle. Hydroelectric dams in this ecoregion also modify the natural flow regime and block the movements of migratory fish species. Oil development and pipelines occur primarily in the Cordillera Oriental in the Andean portion of the Amazon, and mining activities are relatively widespread. Roads and railroads open up access to the region and increase levels of hunting and fishing. Habitat protection is severely hampered in the northwest portion of the basin where illegal narcotics activities predominate.
pper Paraná Rivers and Streams [153] – Argentina, Brazil, Paraguay Geographic Location: Central and South-central South America Biodiversity Features: The upper Paraná River and its tributaries are distinguished both by their spectacular waterfalls, and by their exceptional levels of freshwater biodiversity. The upper Paraná basin supports over 300 species of fish, with a high degree of local endemism in individual tributaries that is likely the result of isolation by waterfalls. The Rio Iguaçu, which is isolated from the Paraná River by the Iguaçu Falls, supports 65 species of fish, of which about 50 species are endemic. There is also high richness of other aquatic organisms, both vertebrates and invertebrates. Many fishes in this river system are migratory and may travel hundreds of kilometers upstream to spawn—often timed to coincide with spring flood peaks. RICH LARGE RIVER ECOSYSTEM WITH HIGH LEVEL OF ENDEMISM IN INDIVIDUAL TRIBUTARIES AND MAIN RIVER Selected Species: Among the migratory species present are a number of characiformes, including Prochilodus lineatus and Salminus maxillosus. One of the few anadromous species in this ecoregion is Atlantic sabretooth anchovy (Lycengraulis grossidens), which ascends the Paraguay River from the Atlantic and has been reported in the southernmost end of the upper Paraná River. The only species of lungfish found in the Neotropics, Lepidosiren paradoxa, inhabits these waters. Two well-known pirana species, Serrasalmus spilopleura and S. marginatus, occur here as well. General Threats: Impoundments, water diversions, hidrovias, and agriculture are among the biggest threats in this ecoregion. The Itaipu hydroelectric dam, with a massive generating capacity of over 12,000 MW, was built in 1979 on the Iguaçu River. Its construction flooded approximately 100,000 ha of land, and destroyed important aquatic habitats, including Guaíra Falls. The Yacyreta dam, on the Paraná River, will flood approximately 80,000 ha when completed. These two dams have together effectively blocked fish migrations. A third dam is on the Acaray River, a tributary to the Paraná, and a number of additional dams are planned within the ecoregion. Also planned is the Hidrovia Paraguay-Paraná, a waterway of approximately 3,440 km that would require dredging the Paraná and Paraguay Rivers. The transportation of crops, particularly soybeans, is one of the goals of the waterway. Soybean agriculture in the ecoregion is widespread and growing; burning of land for soybean plantations, and desertification of the land, has affected the quality of water in the rivers through excessive siltation, and fish populations may be declining. Agricultural pesticides also foul freshwater habitats, as does untreated domestic sewage from urban areas. An oil spill of one million gallons on the Iguaçu River in July 2000, the result of a ruptured pipe at a refinery, highlighted the risks associated with oil development and transportation in the ecoregion. Introduced species also pose threats to this ecoregion’s highly endemic fauna, as do overfishing and poaching.
razilian Shield Amazonian Rivers and Streams [154] – Brazil, Bolivia, Paraguay Geographic Location: Central South America Biodiversity Features: The Brazilian Shield is the pre-Cambrian geologic formation lying primarily south of the Amazon River. The ancient sediments of the Brazilian Shield are well weathered, and the tributaries draining them tend to be nutrient-poor “clearwater” rivers, named for their transparency. Despite the low nutrient content of the water, these rivers are believed to contain exceptional levels of aquatic diversity, particularly for fish. Many fish may be migratory, ascending the tributaries from larger rivers downstream as water levels change. the largest and most distinctive clearwater river biota of south america, including large-scale fish migrations Selected Species: Similar to the Upper Amazon Rivers and Streams (Ecoregion 152, see above), this ecoregion includes species from a number of fish families. Fish groups with high numbers of species represented in this ecoregion include characins (e.g. tetras, piranhas, pacus), catfishes (e.g. doradids, loricariids, pimelodids), gymnotoids (“electric eels”), osteoglossids (relic “bony-tongues), and cichlids. Other aquatic taxa are expected to show high levels of diversity as well. General Threats: This ecoregion comprises the most altered part of the Amazon basin. The Transamazon Highway cuts across this ecoregion, and numerous other roads connect the ecoregion with areas to the south. Petroleum and mineral exploration are widespread in this ecoregion, as are logging concessions and large areas of deforestation. Several dams are in operation or under construction, and dozens of sites have been proposed for new dams, particularly in the basins of the Tocantins/Araguaia, Xingu, Trombetas, and Tapajos rivers. Agricultural expansion, pasture development, and overexploitation of aquatic species pose additional threats. Directory: downloads downloads -> Northern England’s set-jetting locations downloads -> Dynatest 3031 lwd light Weight Deflectometer downloads -> Forth coming competitive exams downloads -> Brush High School Morning Announcements Friday, September 05, 2014 all school downloads -> Year 9 The Arts — Music downloads -> Years 7 and 8 standard elaborations — Australian Curriculum: Music draft downloads -> Chris Young sets 2016 “I’m Comin’ Over” Tour headlining dates downloads -> Slavery and Abolition: the Plymouth Connection Introduction downloads -> Summer Assignment Download 2.75 Mb. Share with your friends:
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