Editing Mekong (section)

==Natural history==
[[File:Pelochelys cantorii.jpg|thumb|Extirpated from most of its pan-Asian range, [[Cantor's giant softshell turtle]] can still be found along a stretch of the Mekong in Cambodia (Khmer called "Kanteay")]]

The Mekong basin is one of the richest areas of biodiversity in the world. Only the [[Amazon Basin|Amazon]] boasts a higher level of bio-diversity.<ref name="MRC_2010a" /> Biota estimates for the [[Greater Mekong Subregion]] (GMS) include 20,000 plant species, 430 mammals, 1,200 birds, 800 reptiles and amphibians,<ref>{{cite web |author=C. Thompson |year=2008 |title=First Contact in the Greater Mekong |publisher=[[World Wide Fund for Nature|WWF]] Greater Mekong Program |url=http://www.wwf.dk/dk/Service/Bibliotek/WWF+i+Asien/Rapporter+mv./First+Contact+in+the+Greater+Mekong |format=[[Portable Document Format|PDF]]}}{{Dead link|date=August 2018 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> and an estimated 850 freshwater fish species (excluding [[euryhaline]] species mainly found in salt or [[brackish]] water, as well as [[introduced species]]).<ref>{{cite web |author=K. G. Hortle |year=2009 |title=Fishes of the Mekong – how many species are there? |publisher=[[Mekong River Commission]] |series=Catch and Culture |url=http://ns1.mrcmekong.org/Catch-Culture/vol15_2Aug09/fishes-of-the-Mekong.htm |url-status=dead |archive-url=https://web.archive.org/web/20120730123927/http://ns1.mrcmekong.org/Catch-Culture/vol15_2Aug09/fishes-of-the-Mekong.htm |archive-date=30 July 2012}}</ref> The most [[Species richness|species rich]] orders among the freshwater fish in the river basin are [[Cypriniformes|cypriniforms]] (377 species) and [[catfish]] (92 species).<ref name=FishValbo>Valbo-Jørgensen, J; Coates, D.; and Hortle, K. (2009). ''Fish diversity in the Mekong River basin.'' pp. 161–196 in: Campbell, I.C. (editor). The Mekong – Biophysical Environment of an International River Basin, 1st edition. Academic Press, Elsevier. {{ISBN|978-0-12-374026-7}}</ref>

[[New species]] are regularly described from the Mekong. In 2009, 145 species previously unknown to science were described from the region, including 29 fish species, 2 bird species, 10 reptiles, 5 mammals, 96 plants, and 6 amphibians.<ref>{{cite web |author1=N. Gephart |author2=G. Blate |author3=C. McQuistan |author4=C. Thompson |year=2010 |title=New Blood: Greater Mekong New Species Discoveries, 2009 |publisher=[[World Wide Fund for Nature|WWF]] |url=http://awsassets.panda.org/downloads/greater_mekong_species_report_web_version_report_1_oct_2010.pdf}}</ref> Between 1997 and 2015, an average of two new species per week were discovered in the region.<ref>{{cite news |title=163 new species, including 'Klingon Newt', discovered |url=https://www.foxnews.com/science/163-new-species-including-klingon-newt-discovered |access-date=20 December 2016 |publisher=[[Fox News]] |date=20 December 2016}}</ref> The Mekong Region contains 16 [[World Wide Fund for Nature|WWF]] [[Global 200]] ecoregions, the greatest concentration of ecoregions in mainland Asia.<ref name="MRC_2010a" />

No other river is home to so many species of very large fish.<ref name=WWF2012>{{cite web |year=2012 |title=River of Giants: Giant Fish of the Mekong |publisher=[[World Wide Fund for Nature|WWF]] Greater Mekong Program |url=http://assets.worldwildlife.org/publications/321/files/original/River_of_Giants_Giant_Fish_of_the_Mekong.pdf}}</ref> The biggest include three species of ''[[Probarbus]]'' barbs, which can grow up to {{cvt|1.5|m|ft|0}} and weigh {{cvt|70|kg|lb|-1}},<ref>{{FishBase genus |genus=Probarbus |month=February |year=2017}}</ref> the [[giant freshwater stingray]] (''Himantura polylepis'', [[syn.]] ''H. chaophraya''), which can reach at least {{cvt|5|m|ft}} in length and {{cvt|1.9|m|ftin}} in width,<ref>{{cite book |author1=Last, P.R. |author2=Compagno, L.J.V. |chapter=Myliobatiformes: Dasyatidae |editor1=Carpenter, K.E. |editor2=Niem, V.H. |title=FAO identification guide for fishery purposes. The living marine resources of the Western Central Pacific |publisher=Food and Agriculture Organization of the United Nations |year=1999 |isbn=92-5-104302-7 |pages=1479–1505}}</ref> the [[giant pangasius]] (''Pangasius sanitwongsei''), [[giant barb]] (''Catlocarpio siamensis'') and the [[Endemism|endemic]] [[Mekong giant catfish]] (''Pangasianodon gigas''). The last three can grow up to about {{cvt|3|m|ft|0}} in length and weigh {{cvt|300|kg|lb}}.<ref name=WWF2012/> All of these have declined drastically because of dams, flood control, and overfishing.<ref name=WWF2012/>

One species of [[freshwater dolphin]], the [[Irrawaddy dolphin]] (''Orcaella brevirostris''), was once common in the whole of the lower Mekong but is now very rare, with only 85 individuals remaining.<ref name=Ryan>{{cite journal |year=2011 |title=Irrawaddy dolphin demography in the Mekong River: an application of mark–resight models |journal=Ecosphere |volume=2 |issue=5 |page=art58 |author1=Ryan, Gerard Edward |author2=Dove, Verne |author3=Trujillo, Fernando |author4=Doherty, Paul F. |doi=10.1890/ES10-00171.1 |doi-access=free |bibcode=2011Ecosp...2...58R }}</ref>

Among other wetland mammals that have been living in and around the river are the [[smooth-coated otter]] (''Lutra perspicillata'') and [[fishing cat]] (''Prionailurus viverrinus'').

The endangered [[Siamese crocodile]] (''Crocodylus siamensis'') occurs in small isolated pockets within the northern Cambodian and Laotian portions of the Mekong River. The [[saltwater crocodile]] (''Crocodylus porosus'') once ranged from the Mekong Delta up the river into Tonle Sap and beyond but is now extinct in the river, along with being extinct in all of Vietnam and possibly even Cambodia.

===Protected areas===
*The headwaters of the Mekong in [[Zadoi County]], Qinghai, China, are protected in [[Sanjiangyuan National Nature Reserve]]. The name Sanjiangyuan means "the sources of the Three Rivers". The reserve also includes the headwaters of the [[Yellow River]] and the [[Yangtze]].
*The section of the river flowing through deep gorges in [[Yunnan]] Province is part of the [[Three Parallel Rivers of Yunnan Protected Areas]], a UNESCO [[World Heritage Site]].
*The [[Tonle Sap Biosphere Reserve]] in Cambodia contains the largest lake in Southeast Asia. It is a UNESCO [[Biosphere reserve]].
[[File:Bank Erosion at Song Tien of Mekong, Binh Dai, Ben Tre, Vietnam.jpg|thumb|Bank erosion on the Song Tien, a Mekong branch, Binh Dai District, Ben Tre Province, Vietnam.]]

===Natural phenomena===
The low tide level of the river in Cambodia is lower than the high tide level out at sea, and the flow of the Mekong inverts with the tides throughout its stretch in Vietnam and up to Phnom Penh. The very flat Mekong delta area in Vietnam is thus prone to flooding, especially in the provinces of An Giang and Dong Thap (Đồng Tháp), near the Cambodian border.