Editing Wetland (section)

== Disturbances and human impacts ==
{{See also|Human impacts on the environment}}

Wetlands, the functions and services they provide as well as their flora and fauna, can be affected by several types of disturbances.<ref>{{Cite journal |last1=Swindles |first1=Graeme T. |last2=Morris |first2=Paul J. |last3=Mullan |first3=Donal J. |last4=Payne |first4=Richard J. |last5=Roland |first5=Thomas P. |last6=Amesbury |first6=Matthew J. |last7=Lamentowicz |first7=Mariusz |last8=Turner |first8=T. Edward |last9=Gallego-Sala |first9=Angela |last10=Sim |first10=Thomas |last11=Barr |first11=Iestyn D. |date=2019-10-21 |title=Widespread drying of European peatlands in recent centuries |url=https://www.nature.com/articles/s41561-019-0462-z |journal=Nature Geoscience |language=en |volume=12 |issue=11 |pages=922–928 |bibcode=2019NatGe..12..922S |doi=10.1038/s41561-019-0462-z |issn=1752-0908 |s2cid=202908362 |hdl-access=free |hdl=10871/39305}} [http://eprints.whiterose.ac.uk/151050/ Alt URL] {{Webarchive|url=https://web.archive.org/web/20200727010653/http://eprints.whiterose.ac.uk/151050/|date=2020-07-27}}</ref> The disturbances (sometimes termed stressors or alterations) can be human-associated or natural, direct or indirect, reversible or not, and isolated or cumulative.

Disturbances include [[Exogeny|exogenous]] factors such as flooding or drought.<ref name="clewell2013" /> Humans are disturbing and damaging wetlands for example by [[oil and gas extraction]], building infrastructure, [[overgrazing]] of [[livestock]], [[overfishing]], alteration of wetlands including [[dredging]] and draining, [[nutrient pollution]] and [[water pollution]].<ref name="clewell2013" /><ref name="mitsch2007" /> Disturbance puts different levels of stress on an environment depending on the type and duration of disturbance.<ref name="clewell2013" /> 

Predominant disturbances of wetlands include:<ref>{{Cite web |author=Office of Research & Development |title=Impacts on quality of inland wetlands of the United States: A survey of indicators, techniques, and applications of community-level biomonitoring data |url=https://cfpub.epa.gov/si/si_public_record_Report.cfm?dirEntryID=39147 |access-date=2018-07-27 |website=cfpub.epa.gov}}</ref><ref>{{Cite book |last1=Adamus |first1=Paul |url=https://www.researchgate.net/publication/323993409 |title=Indicators for Monitoring Biological Integrity of Inland Freshwater Wetlands: A Survey of North American Technical Literature (1990–2000) |last2=J. Danielson |first2=Thomas |last3=Gonyaw |first3=Alex |date=2001-03-24 |publisher=13214 |doi=10.13140/rg.2.2.22371.86566}}</ref>

{{Div col|colwidth=22em}}
* Enrichment/[[eutrophication]]
* Organic loading and reduced dissolved oxygen
* Contaminant [[toxicity]]
* [[Freshwater acidification|Acidification]]
* [[Salinity|Salinization]]
* [[Sedimentation]]
* Altered solar input ([[turbidity]]/shade)
* Vegetation removal
* Thermal alteration
* Drying/[[aridification]]
* Inundation/flooding
* [[Habitat fragmentation]]
* Other human impacts
{{Div col end}}

Disturbances can be further categorized as follows:
* Minor disturbance: Stress that maintains ecosystem integrity.<ref name="clewell2013" />
* Moderate disturbance: Ecosystem integrity is damaged but can recover in time without assistance.<ref name="clewell2013" />
* Impairment or severe disturbance: Human intervention may be needed in order for ecosystem to recover.<ref name="clewell2013" />
[[Nutrient pollution]] comes from nitrogen inputs to aquatic systems and have drastically effected the dissolved nitrogen content of wetlands, introducing higher nutrient availability which leads to [[eutrophication]].<ref>{{Cite journal |last1=Finlay |first1=Jacques C. |last2=Efi Foufoula-Georgiou |author-link2=Efi Foufoula-Georgiou |last3=Dolph |first3=Christine L. |last4=Hansen |first4=Amy T. |date=February 2018 |title=Contribution of wetlands to nitrate removal at the watershed scale |journal=Nature Geoscience |volume=11 |issue=2 |pages=127–132 |bibcode=2018NatGe..11..127H |doi=10.1038/s41561-017-0056-6 |issn=1752-0908 |s2cid=46656300}}</ref>

[[Biodiversity loss]] occurs in wetland systems through [[land use change]]s, [[habitat destruction]], pollution, exploitation of resources, and [[invasive species]]. For example, the introduction of [[water hyacinth]], a native plant of South America into [[Lake Victoria]] in East Africa as well as [[duckweed]] into non-native areas of [[Queensland]], Australia, have overtaken entire wetland systems overwhelming the habitats and reducing the diversity of native plants and animals.{{citation needed|date=August 2024}} 

=== Conversion to dry land ===
To increase economic productivity, wetlands are often converted into dry land with [[Ditch|dykes]] and [[Drainage|drains]] and used for agricultural purposes. The construction of dykes, and dams, has negative consequences for individual wetlands and entire watersheds.<ref name="Keddy2010" />{{rp|497}} Their proximity to lakes and rivers means that they are often developed for human settlement.<ref name="Alexander">{{cite book |last=Alexander |first=David E. |title=Encyclopedia of Environmental Science |date=1 May 1999 |publisher=[[Springer Science+Business Media|Springer]] |isbn=0-412-74050-8}}</ref> Once settlements are constructed and protected by dykes, the settlements then become vulnerable to land subsidence and ever increasing risk of flooding.<ref name="Keddy2010" />{{rp|497}} The Mississippi River Delta around New Orleans, Louisiana is a well-known example;<ref>{{Cite journal |last1=Keddy |first1=P.A. |last2=Campbell |first2=D. |last3=McFalls |first3=T. |last4=Shaffer |first4=G.P. |last5=Moreau |first5=R. |last6=Dranguet |first6=C. |last7=Heleniak |first7=R. |date=2007 |title=The Wetlands of Lakes Pontchartrain and Maurepas: Past, Present and Future |url=http://www.nrcresearchpress.com/doi/10.1139/a06-008 |journal=Environmental Reviews |language=en |volume=15 |issue=NA |pages=43–77 |doi=10.1139/a06-008 |bibcode=2007EnvRv..15...43K |issn=1181-8700}}</ref> the Danube Delta in Europe is another.<ref>Gastescu, P. (1993). The Danube Delta: geographical characteristics and ecological recovery. Earth and Environmental Science, 29, 57–67.</ref>

Water pollution is another key driver of the conversion of wetlands to dry land. Since wetlands tend to retain water with less influx or efflux compared to other bodies of water, they can quickly concentrate toxicants that originate from pollutants.<ref>{{Cite web |last=US EPA |first=ORD |date=2017-11-02 |title=Wetlands |url=https://www.epa.gov/report-environment/wetlands#:~:text=Withdrawal%20of%20ground%20water%20or,can%20accumulate%20in%20wetland%20sediments |access-date=2025-05-07 |website=www.epa.gov |language=en}}</ref> This accumulation of toxicants will cause the biodiversity of a wetland to change, particularly since toxicants will be harmful to native aquatic species.<ref>{{Cite journal |last1=Pal |first1=Swades |last2=Debanshi |first2=Sandipta |date=2022-07-01 |title=Exploring the connection of physical habitat health of the wetland with its gas regulating services |url=https://www.sciencedirect.com/science/article/abs/pii/S1574954122001364 |journal=Ecological Informatics |volume=69 |pages=101686 |doi=10.1016/j.ecoinf.2022.101686 |bibcode=2022EcInf..6901686P |issn=1574-9541}}</ref> The loss of wetland [[biodiversity]] is associated with wetland degradation, as the case of alpine wetlands demonstrates.<ref>{{Cite journal |last1=Qiu |first1=Dongdong |last2=Zhang |first2=Hua |last3=Ren |first3=Yueheng |last4=Zhu |first4=Yanpeng |date=2024-04-01 |title=The lost biodiversity and degraded alpine wetlands caused by strong earthquake on the Qinghai–Tibet Plateau did not self-restore in the short term |url=https://www.sciencedirect.com/science/article/pii/S2351989424000349 |journal=Global Ecology and Conservation |volume=50 |pages=e02830 |doi=10.1016/j.gecco.2024.e02830 |bibcode=2024GEcoC..5002830Q |issn=2351-9894|doi-access=free }}</ref>

=== Drainage of floodplains ===
[[Drainage]] of [[floodplain]]s or development activities that narrow floodplain corridors (such as the construction of [[levee]]s) reduces the ability of coupled river-floodplain systems to control flood damage. That is because modified and less expansive systems must still manage the same amount of precipitation, causing flood peaks to be higher or deeper and floodwaters to travel faster.

Water management engineering developments in the past century have degraded floodplain wetlands through the construction of artificial embankments such as [[Levee|dykes]], bunds, [[levees]], [[weirs]], barrages and [[dams]]. All concentrate water into a main channel and waters that historically spread slowly over a large, shallow area are concentrated. Loss of wetland floodplains results in more severe and damaging flooding. Catastrophic human impact in the Mississippi River floodplains was seen in death of several hundred individuals during a [[2005 levee failures in Greater New Orleans|levee breach in New Orleans caused by Hurricane Katrina]]. Human-made embankments along the Yangtze River floodplains have caused the main channel of the river to become prone to more frequent and damaging flooding.<ref>{{Cite journal |last1=Li |first1=Luqian |last2=Lu |first2=XiXi |last3=Chen |first3=Zhongyuan |date=2007 |title=River channel change during the last 50 years in the middle Yangtze River, the Jianli reach |url=https://linkinghub.elsevier.com/retrieve/pii/S0169555X06003151 |journal=Geomorphology |language=en |volume=85 |issue=3–4 |pages=185–196 |bibcode=2007Geomo..85..185L |doi=10.1016/j.geomorph.2006.03.035}}</ref> Some of these events include the loss of [[riparian vegetation]], a 30% loss of the vegetation cover throughout the river's basin, a doubling of the percentage of the land affected by soil erosion, and a reduction in reservoir capacity through [[siltation]] build-up in floodplain lakes.<ref name="ramsar_a" />

=== Overfishing ===
[[Overfishing]] is a major problem for sustainable use of wetlands. Concerns are developing over certain aspects of farm fishing, which uses natural wetlands and waterways to harvest fish for human consumption. [[Aquaculture]] is continuing to develop rapidly throughout the Asia-Pacific region especially in China where 90% of the total number of aquaculture farms occur, contributing 80% of global value.<ref name="ramsar b" /> Some aquaculture has eliminated massive areas of wetland through practices such as the [[shrimp farming]] industry's destruction of mangroves. Even though the damaging impact of large-scale shrimp farming on the coastal ecosystem in many Asian countries has been widely recognized for quite some time now, it has proved difficult to mitigate since other employment avenues for people are lacking. Also burgeoning demand for shrimp globally has provided a large and ready market.<ref>{{Cite web |title=Shrimp Market Size, Share & Growth Analysis Report, 2030 |url=https://www.grandviewresearch.com/industry-analysis/shrimp-market-report |access-date=2022-11-19 |website=www.grandviewresearch.com |language=en}}</ref>