Editing Amazon river dolphin (section)

===Threats===
The region of the Amazon in Brazil has an extension of {{convert|5000000|km2|mi2|abbr=on}} containing diverse fundamental ecosystems.<ref name="Silvano et al., 2009">{{cite journal|last1=Silvano|first1=R.A.M.|last2=Ramires|first2=M.|last3=Zuanon|first3=J.|title=Effects of fisheries management on fish communities in the floodplain lakes of a Brazilian Amazonian Reserve|journal=Ecology of Freshwater Fish|date=2009|volume=18|issue=1 |pages=156–166|doi=10.1111/j.1600-0633.2008.00333.x|bibcode=2009EcoFF..18..156S }}</ref><ref>{{cite journal|last1=Barletta|first1=M.|last2=Jaureguizar|first2=A.J.|last3=Baigun|first3=C.|last4=Fontoura|first4=N.F.|last5=Agostinho|first5=A.A.|last6=Almeida-Val|first6=V.M.F.|last7=Val|first7=A.L.|last8=Torres|first8=R.A.|last9=Jimenes-Segura|first9=L.F.|last10=Giarrizzo|first10=T.|last11=Fabré|first11=N.N.|last12=Batista|first12=V.S.|last13=Lasso|first13=C. |last14=Taphorn|first14=D.C.|last15=Costa|first15=M.F.|last16=Chaves|first16=P.T.|last17=Vieria|first17=J.P.|last18=Corrêa|first18=M.F.M.|title=Fish and aquatic habitat conservation in South America: A continental overview with an emphasis on Neotropical systems|journal=Journal of Fish Biology|volume=76|issue=9|pages=2118–2176|doi=10.1111/j.1095-8649.2010.02684.x|pmid=20557657|year=2010|bibcode=2010JFBio..76.2118B |url=http://repositorio.furg.br/handle/1/1948}}</ref> One of these ecosystems is a [[floodplain]], or a [[várzea forest]], and is home to a large number of fish species which are an essential resource for human consumption.<ref name="Iriarte 2013">{{cite journal|last1=Iriarte|first1=V.|last2=Marmontel|first2=M.|title=River Dolphin (Inia geoffrensis, Sotalia fluviatilis) Mortality Events Attributed to Artisanal Fisheries in the Western Brazilian Amazon|journal=Aquatic Mammals|date=2013|volume=39|issue=2|pages=116–124|doi=10.1578/am.39.2.2013.116|bibcode=2013AqMam..39..116I }}</ref> The várzea is also a major source of income through excessive local commercialized fishing.<ref name="Silvano et al., 2009"/><ref>{{cite journal|last1=Isaac|first1=V.J.|last2=Ruffino|first2=M.L.|title=Evaluation of fisheries in Middle Amazon|journal=American Fisheries Society Symposium|date=2007|volume=49|pages=587–596}}</ref><ref>{{cite book|last1=Neiland|first1=A.E.|last2=Benê|first2=C.|title=Tropical River Fisheries Valuation:Background papers to a global synthesis|date=2008|publisher=The World Fish Center|location=Penang, Malaysia|page=290}}</ref> Várzea consists of muddy river waters containing a vast number and diversity of nutrient rich species.<ref name="171.66.127.192"/> The abundance of distinct fish species lures the Amazon River dolphin into the várzea areas of high water occurrences during the seasonal flooding.<ref>{{cite journal|author =Arraut, E.M.|author2 =M. Marmontel|author3 =J.E. Mantovani|author4 =E.M. Novo|author5 =D.W. Macdonald|author6 =R.E. Kenward|year=2009|title=The lesser of two evils: seasonal migrations of Amazonian manatees in the Western Amazon|journal= Journal of Zoology|volume=280|number=3|pages=247–256|doi=10.1111/j.1469-7998.2009.00655.x}}</ref>

In addition to attracting predators such as the Amazon river dolphin, these high-water occurrences are an ideal location to draw in the local fisheries. Human fishing activities directly compete with the dolphins for the same fish species, the [[tambaqui]] (''Colossoma macropomum'') and the [[Piaractus brachypomus|pirapitinga]] (''Piaractus brachypomus''), resulting in deliberate or unintentional catches of the Amazon river dolphin.<ref>{{cite book|last1=Reeves|first1=R.R.|last2=Smith|first2=B.D.|last3=Crespo|first3=E.A.|last4=Notarbartolo di Sciara|first4=G.|title=Dolphins, whales and porpoises: 2002–2010 conservation action plan for the world's cetaceans|date=2003|publisher=International Union for Conservation of Nature/Species Survival Committee|location=Gland, Switzerland, and Cambridge, UK|page=139}}</ref><ref name="Martin 2004">{{cite journal|last1=Martin|first1=A.R.|last2=Da Silva|first2=V.M.F.|last3=Rothery|first3=P.|title=Number, seasonal movements, and residency characteristics of river dolphins in an Amazonian floodplain lake system|journal=Canadian Journal of Zoology|date=2008|volume=82|issue=8|pages=1307–1315|doi=10.1139/z04-109}}</ref><ref name="Loch 2009">{{cite journal|last1=Loch|first1=C.|last2=Marmontel|first2=M.|last3=Simões-Lopes|first3=P.C.|title=Conflicts with fisheries and intentional killing of freshwater dolphins (Cetacea: Odontoceti) in the Western Brazilian Amazon|journal=Biodiversity Conservation|date=2009|doi=10.1007/s10531-009-9693-4|volume=18|issue=14|pages=3979–3988|bibcode=2009BiCon..18.3979L |s2cid=20873255}}</ref><ref name="Silvano et al., 2009"/><ref>{{cite book|last1=Beltrán-Pedreros|first1=S.|last2=Filgueiras-Henriques|first2=L.A.|title=Biology, evolution and conservation of river dolphins within South America and Asia|date=2010|publisher=[[Nova Science Publishers, Inc.]]|location=New York|pages=237–246}}</ref><ref name="Crespo 2010b">{{cite journal|last1=Crespo|first1=E.A.|last2=Alarcon|first2=D.|last3=Alonso|first3=M.|last4=Bazzalo|first4=M.|last5=Borobia|first5=M.|last6=Cremer|first6=M.|last7=Filla|first7=G.F.|last8=Lodi|first8=L.|last9=Magalhães|first9=F.A.|last10=Marigo|first10=J.|last11=Queiróz|first11=H.L.|last12=Reynolds|first12=J.E. III|last13=Schaeffer|first13=Y.|last14=Dorneles|first14=P.R.|last15=Lailson-Brito|first15=J.|last16=Wetzel|first16=D.L.|title=Report on the working group on major threats and conservation|journal=The Latin American Journal of Aquatic Mammals|date=2010b|volume=8|issue=1–2|pages=47–56|doi=10.5597/lajam00153|url=http://www.lajamjournal.org/index.php/lajam/article/download/330/256|doi-access=free|hdl=11336/98669|hdl-access=free}}</ref><ref name="Iriarte & Marmontel 2011">{{cite journal|last1=Iriarte|first1=V.|last2=Marmontel|first2=M.|title=Report of an encounter with a human intentionally entagled Amazon River dolphin (Inia geoffrensis) calf and its release in Tefé River, Amazonas State, Brazil|journal=Uakari|date=2011|volume=7|issue=2|pages=47–56}}</ref><ref name="Alves 2012">{{cite journal|last1=Alves|first1=L.C.P.S.|last2=Andriolo|first2=A.|last3=Zappes|first3=C.A.|title=Conflicts between river dolphins (Cetacea:Odontoceti) and fisheries in the Central Amazon: A path toward tragedy?|journal=Zoologia|date=2012|volume=29|issue=5|pages=420–429|doi=10.1590/s1984-46702012000500005|doi-access=free}}</ref> The local fishermen overfish and when the Amazon River dolphins are removed from the commercial catch in the nets and lines, it causes damages to the equipment and the capture, as well as generating ill will from the local fishermen.<ref name="Loch 2009"/><ref name="Crespo 2010b"/><ref name="Iriarte & Marmontel 2011"/> The negative reactions of the local fishermen are also attributed to the [[Brazilian Institute of Environment and Renewable Natural Resources]] prohibition on killing the Amazon river dolphin, yet not compensating the fishermen for the damage done to their equipment and catch.<ref name="Alves 2012"/>

During the process of catching the commercialized fish, the Amazon river dolphins get caught in the nets and exhaust themselves until they die, or the local fishermen deliberately kill the entangled dolphins.<ref name="Iriarte 2013"/> The carcasses are discarded, consumed, or used as bait to attract a scavenger catfish, the [[piracatinga]] (''Calophysus macropterus'').<ref name="Iriarte 2013"/><ref name="Estupiñán">{{cite web|last1=Estupiñán|first1=G.|last2=Marmontel|first2=M.|last3=Queiroz|first3=H.L.|last4=Roberto e Souza|first4=P.|last5=Valsecchi|first5=J.|last6=da Silva Batista|first6=G.|last7=Barbosa Pereira|first7=S.|title=A pesca da piracatinga (''Calophysus macropterus'') na Reserva de Desenvolvimiento Sustentável Mamirauá [The piracatinga fishery (''Calophysus macropterus'') at Mamirauá Sustainable Development Reserve].|url=http://site-antigo.socioambiental.org/website/noticias/agenda/fks/rel_piracatinga.htm|publisher=Brazilian Ministry of Science and Technology|access-date=16 July 2014|archive-date=28 July 2014|archive-url=https://web.archive.org/web/20140728110821/http://site-antigo.socioambiental.org/website/noticias/agenda/fks/rel_piracatinga.htm|url-status=dead}}</ref> The use of the Amazon river dolphin carcass as bait for the piracatinga dates back to 2000.<ref name="Estupiñán"/> Increasing demand for the piracatinga has created a market for distribution of the Amazon river dolphin carcasses to be used as bait throughout these regions.<ref name="Alves 2012"/>

Of the 15 dolphin carcasses found in the [[Japurá River]] in 2010–2011 surveys, 73% of the dolphins were killed for bait, disposed of, or abandoned in entangled gillnets.<ref name="Iriarte 2013"/> The data do not fully represent the actual overall number of deaths of the Amazon river dolphins, whether accidental or intentional, because a variety of factors make it extremely complicated to record and medically examine all the carcasses.<ref name="Iriarte 2013"/><ref name="Martin 2004"/><ref name="Crespo 2010b"/> Scavenger species feed upon the carcasses, and the complexity of the river currents make it nearly impossible to locate all of the dead animals.<ref name="Iriarte 2013"/> More importantly, the local fishermen do not report these deaths out of fear that a legal course of action will be taken against them,<ref name="Iriarte 2013"/> as the Amazon river dolphin and other cetaceans are protected under a Brazilian federal law prohibiting any takes, harassments, and kills of the species.<ref>{{cite journal|last1=Lodi|first1=L.|last2=Barreto|first2=A.|title=Legal actions taken in Brazil for the conservation of cetaceans|journal=Journal of International Wildlife Law and Policy|date=1998|volume=I|issue=3|pages=403–411|doi=10.1080/13880299809353910}}</ref>

The Amazon river is also threatened by the dumping of mercury into its waters from industrial mining, along with other harsh chemicals. Just like deforestation and burning, mercury in the water of the Amazon river is very dangerous for the fauna of the river. In 2019, F. Mosquera-Guerra at al, published a study that showed the presence of mercury in the Amazon river dolphins. They analyzed the dolphin's muscle tissue of different taxa of the Amazon basin and found high concentrations of mercury in the Tapajos River (Brazil) from an adult male of I. g. geoffrensis (pink dolphin).<ref>{{Cite journal|last1=Mosquera-Guerra|first1=F.|last2=Trujillo|first2=F.|last3=Parks|first3=D.|last4=Oliveira-da-Costa|first4=M.|last5=Van Damme|first5=P. A.|last6=Echeverría|first6=A.|last7=Franco|first7=N.|last8=Carvajal-Castro|first8=J. D.|last9=Mantilla-Meluk|first9=H.|last10=Marmontel|first10=M.|last11=Armenteras-Pascual|first11=D.|date=December 2019|title=Mercury in Populations of River Dolphins of the Amazon and Orinoco Basins|url=http://link.springer.com/10.1007/s10393-019-01451-1|journal=EcoHealth|language=en|volume=16|issue=4|pages=743–758|doi=10.1007/s10393-019-01451-1|pmid=31712931 |s2cid=207942099 |issn=1612-9202}}</ref>

In September 2023, 154 Amazon river dolphins died in Brazil's Lake Tefé following record-high water temperatures of {{convert|40|C}} and reduced water levels during a drought. While there are ongoing studies by the Mamirauá Institute for Sustainable Development to determine the cause of the deaths, the leading hypothesis is that the elevated temperature caused algae in the lake to release a toxin that attacks the central nervous system.<ref name="Mongabay">{{cite news |last1=Arellano |first1=Astrid |title=11 countries sign global pact to protect endangered river dolphins |url=https://news.mongabay.com/2024/01/11-countries-sign-global-pact-to-protect-endangered-river-dolphins/ |work=Mongabay Environmental News |date=15 January 2024}}</ref><ref>{{cite news |last1=Ionova |first1=Ana |last2=Albeck-Ripka |first2=Livia |title=A Lake Turned to a Hot 'Soup.' Then the River Dolphins Died. |url=https://www.nytimes.com/2023/10/04/us/amazon-river-dolphins-dead-heat-drought.html |work=The New York Times |date=4 October 2023}}</ref>