Editing Mayfly (section)

== Conservation ==

The nymph is the dominant life history stage of the mayfly. Different insect species vary in their tolerance to water pollution, but in general, the larval stages of mayflies, stoneflies (Plecoptera) and caddis flies (Trichoptera) are susceptible to a number of pollutants including [[sewage]], [[pesticide]]s and [[industrial effluent]]. In general, mayflies are particularly sensitive to [[Freshwater acidification|acidification]], but tolerances vary, and certain species are exceptionally tolerant to [[Toxic heavy metal|heavy metal]] contamination and to low [[pH]] levels. [[Ephemerellidae]] are among the most tolerant groups and [[Siphlonuridae]] and [[Caenidae]] the least. The adverse effects on the insects of pollution may be either lethal or sub-lethal, in the latter case resulting in altered enzyme function, poor growth, changed behaviour or lack of reproductive success. As important parts of the food chain, pollution can cause knock-on effects to other organisms; a dearth of herbivorous nymphs can cause overgrowth of algae, and a scarcity of predacious nymphs can result in an over-abundance of their prey species.<ref name=Capinera>{{cite book |last=Capinera |first=John L. |title=Encyclopedia of Entomology |url=https://books.google.com/books?id=i9ITMiiohVQC&pg=PA4158 |year=2008 |publisher=[[Springer Science+Business Media]] |isbn=978-1-4020-6242-1 |pages=4158–4165 }}</ref> Fish that feed on mayfly nymphs that have [[Bioaccumulation|bioaccumulated]] heavy metals are themselves at risk.<ref>{{cite book |last1=Di Giulio |first1=Richard T. |last2=Hinton |first2=David E. |title=The Toxicology of Fishes |url=https://books.google.com/books?id=aOfEXLNMLugC&pg=PA794 |year=2008 |publisher=[[CRC Press]] |isbn=978-0-203-64729-5 |page=794}}</ref> Adult female mayflies find water by detecting the [[polarization (waves)|polarization]] of reflected light. They are easily fooled by other polished surfaces which can act as traps for swarming mayflies.<ref name=polarized />

The threat to mayflies applies also to their eggs. "Modest levels" of pollution in rivers in England are sufficient to kill 80% of mayfly eggs, which are as vulnerable to pollutants as other life-cycle stages; numbers of the [[blue-winged olive mayfly]] (''Baetis'') have fallen dramatically, almost to none in some rivers. The major pollutants thought to be responsible are fine sediment and phosphate from agriculture and sewage.<ref>{{cite news |last=Carrington |first=Damian |title=Insect declines: new alarm over mayfly is 'tip of iceberg', warn experts |url=https://www.theguardian.com/environment/2018/jan/11/insect-declines-new-alarm-over-mayfly-is-tip-of-iceberg-warn-experts |access-date=11 January 2018 |work=The Guardian |date=11 January 2018}}</ref>

The status of many species of mayflies is unknown because they are known from only the original collection data. Four North American species are believed to be extinct. Among these, ''[[Pentagenia robusta]]'' was originally collected from the [[Ohio River]] near [[Cincinnati]], but this species has not been seen since its original collection in the 1800s. ''[[Ephemera compar]]'' is known from a single specimen, collected from the "foothills of Colorado" in 1873, but despite intensive surveys of the Colorado mayflies reported in 1984, it has not been rediscovered.<ref>{{cite journal |last1=Edmunds |first1=G. F. Jr. |last2=McCafferty |first2=W. P. |year=1984 |title=''Ephemera compar'': an obscure Colorado burrowing mayfly (Ephemeroptera: Ephemeridae) |journal=Entomological News |volume=95 |pages=186–188 |url=http://www.ephemeroptera-galactica.com/pubs/pub_e/pubedmundsg1984p186.pdf }}</ref>

The [[International Union for Conservation of Nature]] (IUCN) [[red list]] of threatened species includes one mayfly: ''[[Tasmanophlebia lacuscoerulei]]'', the large blue lake mayfly, which is a native of Australia and is listed as [[endangered]] because its alpine habitat is [[vulnerable to climate change]].<ref>{{Cite iucn |last=Suter |first=P. |title=''Tasmanophlebi lacuscoerulei'' |volume=2014 |page=e.T40728A21425993 |date=2014 |doi=10.2305/IUCN.UK.2014-1.RLTS.T40728A21425993.en }}</ref>