A clearwater river is classified based on its chemistry, sediments and water colour. Clearwater rivers have a low conductivity, relatively low levels of dissolved solids, typically have a neutral to slightly acidicpH and are very clear with a greenish colour.[2][3][4] Clearwater rivers often have fast-flowing sections.[3]
Like many clearwater rivers, the Xingu has sections with rapids that are home to many threatened rheophilic fish found nowhere else in the world[1]
The main clearwater rivers are South American and have their source in the Brazilian Plateau or the Guiana Shield.[4][5][6] Outside South America the classification is not commonly used, but rivers with clearwater characteristics are found elsewhere.[7]
Amazonian rivers fall into three main categories: clearwater, blackwater and whitewater. This classification system was first proposed by Alfred Russel Wallace in 1853 based on water colour, but the types were more clearly defined according to chemistry and physics by Harald Sioli [de] from the 1950s to the 1980s.[2][8][9] Although many Amazonian rivers fall clearly into one of these categories, others show a mix of characteristics and may vary depending on season and flood levels.[9][10]
Outside South America the classification is not commonly used, but rivers with clearwater characteristics are found elsewhere, such as the upper Zambezi River, certain upland streams in major river basins of South and Southeast Asia, and many streams of northern Australia.[7]
In South America, clearwater rivers typically have their source and flow through regions with sandy soils and crystalline rocks. These are generally ancient, of Precambrian origin, and therefore heavily weathered, allowing relatively few sediments to be dissolved in the water.[2][4] This results in the low conductivity, relatively low levels of dissolved solids and clear colour typical of clearwater rivers.[2]
Sand and kaolinite are the typical sediments transported by clearwater rivers, similar to blackwater, but unlike whitewater that also transports high levels of illite and montmorillonite, resulting in a significantly higher fertility of places influenced by the latter river type.[8] Nevertheless, although clearwater rivers can have extremely low nutrient levels similar to blackwater, some such as the Tapajós, Xingu and Tocantins have nutrient levels that are intermediate between black and whitewater.[8] The exact chemistry of clearwater rivers varies,[8] but it is often very similar to rainwater, low in major nutrients with sodium as the relatively dominating chemical.[14]
The water is typically neutral to slightly acidic,[4][14] but the pH can range between 4.5[8] and 8.[2] In the Amazon basin, clearwater rivers flowing through regions with sediments of Tertiary age are typically highly acidic, while those flowing through sediments of Carboniferous age are closer to neutral or slightly basic.[8]
As suggested by the name, clearwater rivers are highly transparent with a typical visibility of 1.5–4 m (5–13 ft).[15] There can be large variations, even within a single river, depending on season or heavy rains.[8]
The zebra pleco is one of the many species, including several other catfish, that are restricted to clearwater rivers and threatened by dams[16][17]
The difference in chemistry and visibility between the various black, white and clearwater rivers result in distinct differences in flora and fauna.[2] Although there is considerable overlap in the fauna found in the different river types, there are also many species found only in one of them.[18][19][20] Many blackwater and clearwater species are restricted to relatively small parts of the Amazon, as different blackwater and clearwater systems are separated (and therefore isolated) by large whitewater sections.[2][19] These "barriers" are considered a main force in allopatric speciation in the Amazon basin.[2]
Many species of fish, which often are threatened (especially by dams), are only known from clearwater rivers.[1][2] Large sections with rapids are home to specialized, rheophilic fish,[1][17] as well as aquatic plants such as Podostemaceae.[8][22] There are major differences in the amount of macrophytes and this is mainly related to light: heavily shaded clearwater rivers have few, while those flowing through more open regions often contain many.[8] Clearwater rivers have relatively low productivity compared to whitewater rivers, resulting in a comparably low insect abundance.[4]
Referencesedit
^ abcAndrade, M.C.; L.M. Sousa; R.P. Ota; M. Jégu; T. Giarrizzo (2016). "Redescription and Geographical Distribution of the Endangered Fish Ossubtus xinguense Jégu 1992 (Characiformes, Serrasalmidae) with Comments on Conservation of the Rheophilic Fauna of the Xingu River". PLOS ONE. 11 (9): e0161398. Bibcode:2016PLoSO..1161398A. doi:10.1371/journal.pone.0161398. PMC5035070. PMID 27662358.
^ abcdefghiDuncan, W.P.; M.N. Fernandes (2010). "Physicochemical characterization of the white, black, and clearwater rivers of the Amazon Basin and its implications on the distribution of freshwater stingrays (Chondrichthyes, Potamotrygonidae)". PanamJAS. 5 (3): 454–464.
^ abcdefgvan der Sleen, P.; J.S. Albert, eds. (2017). Field Guide to the Fishes of the Amazon, Orinoco, and Guianas. Princeton University Press. pp. 13–18. ISBN978-0-691-17074-9.
^ abcJunk, W.J.; Piedade, M.T.F.; Schöngart, J.; Cohn-Haft, M.; Adeney, J.M.; Wittmann, F.A. (2011). "Classification of Major Naturally-Occurring Amazonian Lowland Wetlands". Wetlands. 31 (4): 623–640. doi:10.1007/s13157-011-0190-7. S2CID 36001397.
^ abcVenticinque; Forsberg; Barthem; Petry; Hess; Mercado; Cañas; Montoya; Durigan; Goulding (2016). "An explicit GIS-based river basin framework for aquatic ecosystem conservation in the Amazon". Earth Syst. Sci. Data. 8 (2): 651–661. Bibcode:2016ESSD....8..651V. doi:10.5194/essd-8-651-2016.
^ abWinemiller, K.O.; A.A. Agostinho; É.P. Caramaschi (2008). "Fish Ecology in Tropical Streams". In Dudgeon, D. (ed.). Tropical Stream Ecology. Academic Press. pp. 112–113. ISBN978-0-12-088449-0.
^ abcdefghiSioli, H., ed. (1984). The Amazon: Limnology and landscape ecology of a mighty tropical river and its basin. pp. 160–161, 219, 276–280, 445, 493–494. ISBN978-94-009-6544-7.
^ abcRíos-Villamizar, E.A.; M.T.F. Piedade; J.G. da Costa; J.M. Adeney; J. Junk (2013). "Chemistry of different Amazonian water types for river classification: A preliminary review".
^Goulding, M.; M.L. Carvalho (1982). "Life history and management of the tambaqui (Colossoma macropomum, Characidae): an important Amazonian food fish". Revista Brasileira de Zoologia. 1 (2): 107–133. doi:10.1590/S0101-81751982000200001.
^Blettler, M.C.M; M.L. Amsler; I.E. de Drago; L.A. Espinola; E. Eberle; A. Paira; J.L. Best; D.R. Parsons; E.E. Drago (2007). "The impact of significant input of fine sediment on benthic fauna at tributary junctions: A case study of the Bermejo-Paraguay River confluence, Argentina" (PDF). Ecohydrology. 8 (2): 340–352. doi:10.1002/eco.1511. hdl:11336/31047. S2CID 55234507.
^"Waters". Amazon Waters. Retrieved 10 October 2017.
^Mol, J.H.; B. de Mérona; P.E. Ouboter; S. Sahdew (2007). "The fish fauna of Brokopondo Reservoir, Suriname, during 40 years of impoundment". Neotrop. Ichthyol. 5 (3): 351–368. doi:10.1590/S1679-62252007000300015.
^ ab"Clearwater Rivers". Amazon Waters. Retrieved 1 October 2017.
^Goulding, M. (1981). Man and Fisheries on an Amazon Frontier. p. 10. ISBN978-90-481-8520-7.
^"Habitat". zebrapleco.com. Retrieved 10 October 2017.
^ abHyland, T.; M.H.S. Perez. "Race against time". Exel Magazine. Retrieved 10 October 2017.
^Saint-Paul, U.; J. Zuanon; M.A. Villacorta Correa; M. García; N.N. Fabré; U. Berger; W.J. Junk (2000). "Fish communities in Central Amazonian white and blackwater floodplains". Environmental Biology of Fishes. 57 (3): 235–250. doi:10.1023/A:1007699130333. S2CID 25361090.
^Henderson, P.A.; W.G.R. Crampton (1997). "A comparison of fish diversity and abundance between nutrient-rich and nutrient-poor lakes in the Upper Amazon". Journal of Tropical Ecology. 13 (2): 175–198. doi:10.1017/s0266467400010403. S2CID 84919041.
^de Carvalho, M.R. (2016). "Description of two extraordinary new species of freshwater stingrays of the genus Potamotrygon endemic to the rio Tapajós basin, Brazil (Chondrichthyes: Potamotrygonidae), with notes on other Tapajós stingrays". Zootaxa. 4167 (1): 1–63. doi:10.11646/zootaxa.4167.1.1. PMID 27701358.
^Collinson, A.S. (1988). Introduction to World Vegetation (2 ed.). p. 222. ISBN0-04-581031-1.
October 27, 2023
clearwater, river, river, type, clearwater, river, classified, based, chemistry, sediments, water, colour, clearwater, rivers, have, conductivity, relatively, levels, dissolved, solids, typically, have, neutral, slightly, acidic, very, clear, with, greenish, c. A clearwater river is classified based on its chemistry sediments and water colour Clearwater rivers have a low conductivity relatively low levels of dissolved solids typically have a neutral to slightly acidic pH and are very clear with a greenish colour 2 3 4 Clearwater rivers often have fast flowing sections 3 Like many clearwater rivers the Xingu has sections with rapids that are home to many threatened rheophilic fish found nowhere else in the world 1 The main clearwater rivers are South American and have their source in the Brazilian Plateau or the Guiana Shield 4 5 6 Outside South America the classification is not commonly used but rivers with clearwater characteristics are found elsewhere 7 Amazonian rivers fall into three main categories clearwater blackwater and whitewater This classification system was first proposed by Alfred Russel Wallace in 1853 based on water colour but the types were more clearly defined according to chemistry and physics by Harald Sioli de from the 1950s to the 1980s 2 8 9 Although many Amazonian rivers fall clearly into one of these categories others show a mix of characteristics and may vary depending on season and flood levels 9 10 Contents 1 Location 2 Chemistry and sediments 3 Ecology 4 ReferencesLocation edit nbsp Map of the Amazon basin Tributaries of the Amazon River in the eastern part of the basin are typically clearwaterThe main clearwater rivers are South American and have their source in the Brazilian Plateau or the Guiana Shield Examples of clearwater rivers originating in the Brazilian Plateau include Tapajos Xingu Tocantins several large right bank tributaries of the Madeira notably Guapore Ji Parana and Aripuana and Paraguay although heavily influenced by its whitewater tributaries 4 5 6 11 The Tapajos and Xingu alone account for 6 and 5 respectively of the water in the Amazon basin 12 Examples of clearwater rivers originating in the Guiana Shield include the upper Orinoco above the inflow of the blackwater Atabapo and whitewater Inirida Guaviare Ventuari Nhamunda Trombetas Paru Araguari and Suriname 4 5 6 13 Outside South America the classification is not commonly used but rivers with clearwater characteristics are found elsewhere such as the upper Zambezi River certain upland streams in major river basins of South and Southeast Asia and many streams of northern Australia 7 Chemistry and sediments edit nbsp The confluence of the Madeira River and Aripuana River dark Despite its colour on this photo Aripuana is clearwater while the Madeira is whitewaterIn South America clearwater rivers typically have their source and flow through regions with sandy soils and crystalline rocks These are generally ancient of Precambrian origin and therefore heavily weathered allowing relatively few sediments to be dissolved in the water 2 4 This results in the low conductivity relatively low levels of dissolved solids and clear colour typical of clearwater rivers 2 Sand and kaolinite are the typical sediments transported by clearwater rivers similar to blackwater but unlike whitewater that also transports high levels of illite and montmorillonite resulting in a significantly higher fertility of places influenced by the latter river type 8 Nevertheless although clearwater rivers can have extremely low nutrient levels similar to blackwater some such as the Tapajos Xingu and Tocantins have nutrient levels that are intermediate between black and whitewater 8 The exact chemistry of clearwater rivers varies 8 but it is often very similar to rainwater low in major nutrients with sodium as the relatively dominating chemical 14 The water is typically neutral to slightly acidic 4 14 but the pH can range between 4 5 8 and 8 2 In the Amazon basin clearwater rivers flowing through regions with sediments of Tertiary age are typically highly acidic while those flowing through sediments of Carboniferous age are closer to neutral or slightly basic 8 As suggested by the name clearwater rivers are highly transparent with a typical visibility of 1 5 4 m 5 13 ft 15 There can be large variations even within a single river depending on season or heavy rains 8 Average physico chemical characteristics 9 Jurua River typical whitewater Tapajos River typical clearwater Tefe River typical blackwater pH 7 27 6 56 5 03Electric conductivity mS cm 191 14 14 33 7 36Total suspended solids mg L 51 42 10 56 7 90Ca mg L 32 55 0 52 0 71Mg mg L 4 42 0 26 0 22Na mg L 10 19 1 50 0 40K mg L 1 98 0 93 1 41Total P mg L 0 080 0 010 0 033CO3 mg L 106 14 8 80 6 86NO3 mg L 0 031 0 040 0 014NH4 mg L 0 062 0 19 0 13Total N mg L 0 39 0 35 0 24SO4 mg L 2 56 0 30 4 20Colour mg Pt L 41 61 4 02 54 90Si mg L 5 78 5 25 0 33Cl mg L 4 75 0 53 0 85Ecology edit nbsp The zebra pleco is one of the many species including several other catfish that are restricted to clearwater rivers and threatened by dams 16 17 The difference in chemistry and visibility between the various black white and clearwater rivers result in distinct differences in flora and fauna 2 Although there is considerable overlap in the fauna found in the different river types there are also many species found only in one of them 18 19 20 Many blackwater and clearwater species are restricted to relatively small parts of the Amazon as different blackwater and clearwater systems are separated and therefore isolated by large whitewater sections 2 19 These barriers are considered a main force in allopatric speciation in the Amazon basin 2 nbsp Potamotrygon leopoldi is part of a species complex of blackish river rays with contrasting pale spots from Brazilian clearwater rivers 21 Many species of fish which often are threatened especially by dams are only known from clearwater rivers 1 2 Large sections with rapids are home to specialized rheophilic fish 1 17 as well as aquatic plants such as Podostemaceae 8 22 There are major differences in the amount of macrophytes and this is mainly related to light heavily shaded clearwater rivers have few while those flowing through more open regions often contain many 8 Clearwater rivers have relatively low productivity compared to whitewater rivers resulting in a comparably low insect abundance 4 References edit a b c Andrade M C L M Sousa R P Ota M Jegu T Giarrizzo 2016 Redescription and Geographical Distribution of the Endangered Fish Ossubtus xinguense Jegu 1992 Characiformes Serrasalmidae with Comments on Conservation of the Rheophilic Fauna of the Xingu River PLOS ONE 11 9 e0161398 Bibcode 2016PLoSO 1161398A doi 10 1371 journal pone 0161398 PMC 5035070 PMID 27662358 a b c d e f g h i Duncan W P M N Fernandes 2010 Physicochemical characterization of the white black and clearwater rivers of the Amazon Basin and its implications on the distribution of freshwater stingrays Chondrichthyes Potamotrygonidae PanamJAS 5 3 454 464 a b Giovanetti T A Vriends M M 1991 Discus Fish Barron s Educational Serie p 15 ISBN 0 8120 4669 2 a b c d e f g van der Sleen P J S Albert eds 2017 Field Guide to the Fishes of the Amazon Orinoco and Guianas Princeton University Press pp 13 18 ISBN 978 0 691 17074 9 a b c Junk W J Piedade M T F Schongart J Cohn Haft M Adeney J M Wittmann F A 2011 Classification of Major Naturally Occurring Amazonian Lowland Wetlands Wetlands 31 4 623 640 doi 10 1007 s13157 011 0190 7 S2CID 36001397 a b c Venticinque Forsberg Barthem Petry Hess Mercado Canas Montoya Durigan Goulding 2016 An explicit GIS based river basin framework for aquatic ecosystem conservation in the Amazon Earth Syst Sci Data 8 2 651 661 Bibcode 2016ESSD 8 651V doi 10 5194 essd 8 651 2016 a b Winemiller K O A A Agostinho E P Caramaschi 2008 Fish Ecology in Tropical Streams In Dudgeon D ed Tropical Stream Ecology Academic Press pp 112 113 ISBN 978 0 12 088449 0 a b c d e f g h i Sioli H ed 1984 The Amazon Limnology and landscape ecology of a mighty tropical river and its basin pp 160 161 219 276 280 445 493 494 ISBN 978 94 009 6544 7 a b c Rios Villamizar E A M T F Piedade J G da Costa J M Adeney J Junk 2013 Chemistry of different Amazonian water types for river classification A preliminary review Goulding M M L Carvalho 1982 Life history and management of the tambaqui Colossoma macropomum Characidae an important Amazonian food fish Revista Brasileira de Zoologia 1 2 107 133 doi 10 1590 S0101 81751982000200001 Blettler M C M M L Amsler I E de Drago L A Espinola E Eberle A Paira J L Best D R Parsons E E Drago 2007 The impact of significant input of fine sediment on benthic fauna at tributary junctions A case study of the Bermejo Paraguay River confluence Argentina PDF Ecohydrology 8 2 340 352 doi 10 1002 eco 1511 hdl 11336 31047 S2CID 55234507 Waters Amazon Waters Retrieved 10 October 2017 Mol J H B de Merona P E Ouboter S Sahdew 2007 The fish fauna of Brokopondo Reservoir Suriname during 40 years of impoundment Neotrop Ichthyol 5 3 351 368 doi 10 1590 S1679 62252007000300015 a b Clearwater Rivers Amazon Waters Retrieved 1 October 2017 Goulding M 1981 Man and Fisheries on an Amazon Frontier p 10 ISBN 978 90 481 8520 7 Habitat zebrapleco com Retrieved 10 October 2017 a b Hyland T M H S Perez Race against time Exel Magazine Retrieved 10 October 2017 Saint Paul U J Zuanon M A Villacorta Correa M Garcia N N Fabre U Berger W J Junk 2000 Fish communities in Central Amazonian white and blackwater floodplains Environmental Biology of Fishes 57 3 235 250 doi 10 1023 A 1007699130333 S2CID 25361090 a b Kullander S O 1986 Cichlid fishes of the Amazon River drainage of Peru Swedish Museum of Natural History ISBN 91 86510 04 5 Henderson P A W G R Crampton 1997 A comparison of fish diversity and abundance between nutrient rich and nutrient poor lakes in the Upper Amazon Journal of Tropical Ecology 13 2 175 198 doi 10 1017 s0266467400010403 S2CID 84919041 de Carvalho M R 2016 Description of two extraordinary new species of freshwater stingrays of the genus Potamotrygon endemic to the rio Tapajos basin Brazil Chondrichthyes Potamotrygonidae with notes on other Tapajos stingrays Zootaxa 4167 1 1 63 doi 10 11646 zootaxa 4167 1 1 PMID 27701358 Collinson A S 1988 Introduction to World Vegetation 2 ed p 222 ISBN 0 04 581031 1 Retrieved from https en wikipedia org w index php title Clearwater river river type amp oldid 1170520293, wikipedia, wiki, book, books, library,
