Editing Mayfly (section)

===Ecology===
[[File: Rainbow trout fish on water surface.jpg|thumb|[[Rainbow trout]] are among the main predators of mayflies.]]

Nymphs live primarily in streams under rocks, in decaying vegetation or in sediments. Few species live in lakes, but they are among the most prolific. For example, the emergence of one species of ''[[Hexagenia]]'' was recorded on [[Doppler weather radar]] by the shoreline of [[Lake Erie]] in 2003.<ref>{{cite web |url=http://www.pserie.psu.edu/seagrant/publications/fs/Mayfly_12-2003.pdf |title=Return of the mayfly: an indicator of an improving habitat |publisher=Pennsylvania Sea Grant |year=2003 |archive-url=https://web.archive.org/web/20070927230149/http://www.pserie.psu.edu/seagrant/publications/fs/Mayfly_12-2003.pdf |archive-date=27 September 2007 |access-date=30 May 2015 }}</ref> In the nymphs of most mayfly species, the paddle-like gills do not function as respiratory surfaces because sufficient oxygen is absorbed through the integument, instead serving to create a respiratory current. However, in low-oxygen environments such as the mud at the bottom of ponds in which ''[[Ephemera vulgata]]'' burrows, the filamentous gills act as true accessory respiratory organs and are used in gaseous exchange.<ref>{{cite journal |last=Wingfield |first=C. A. |year=1939 |title=The function of the gills of mayfly nymphs from different habitats |journal=Journal of Experimental Biology |volume=16 |issue=3 |pages=363–373 |doi=10.1242/jeb.16.3.363 |issn=1477-9145 |url=http://jeb.biologists.org/content/jexbio/16/3/363.full.pdf}}</ref>

In most species, the nymphs are [[herbivore]]s or [[detritivore]]s, feeding on [[algae]], [[diatom]]s or [[detritus]], but in a few species, they are [[predators]] of [[chironomid]] and other small insect larvae and nymphs.<ref>{{cite journal|journal=Aquatic Insects| volume=22 |year=2000| issue= 2| pages=148–159 |title= Guloptiloides: an Extraordinary New Carnivorous Genus of Baetidae (Ephemeroptera) |last1=Gattolliat |first1=Jean-Luc |last2=Sartori |first2=Michel | doi=10.1076/0165-0424(200004)22:2;1-p;ft148| s2cid=86012067 }}</ref><ref>{{cite journal|journal=Aquatic Insects| volume=8| issue=2| year=1986| title= Comparative mouthpart morphology and evolution of the carnivorous heptageniidae (Ephemeroptera) | doi=10.1080/01650428609361236 |last1=McCafferty |first1=W. P. |last2=Provonsha |first2=A. V. | pages=83–89}}</ref> Nymphs of ''[[Povilla]]'' burrow into submerged wood and can be a problem for boat owners in Asia.<ref name=thorpcovich>{{cite book|title=Thorp and Covich's Freshwater Invertebrates|edition=4th| editor=Thorp| editor2=Rogers|year=2014| publisher=[[Academic Press]] |chapter=Order Ephemeroptera| author1=Sartori, Michel| author2=Brittain, John E.|pages=873–891}}</ref> Some are able to shift from one feeding group to another as they grow, thus enabling them to utilise a variety of food resources. They process a great quantity of organic matter as nymphs and transfer a lot of phosphates and nitrates to terrestrial environments when they emerge from the water, thus helping to remove pollutants from aqueous systems.<ref name=Dominguez/> Along with [[caddisfly]] larvae and [[gastropoda|gastropod molluscs]], the grazing of mayfly nymphs has a significant impact on the [[primary producers]], the plants and algae, on the bed of streams and rivers.<ref name=Hauer>{{cite book |last1=Hauer |first1=F. Richard |last2=Lamberti |first2=Gary A.|title=Methods in Stream Ecology |url=https://books.google.com/books?id=rlclsSCF_dQC&pg=PA538 |year=2011 |publisher=[[Academic Press]] |isbn=978-0-08-054743-5 |pages=538, 561}}</ref>

The nymphs are eaten by a wide range of predators and form an important part of the aquatic [[food chain]]. Fish are among the main predators, picking nymphs off the bottom or ingesting them in the water column, and feeding on emerging nymphs and adults on the water surface. Carnivorous [[stonefly]], [[caddisfly]], [[alderfly]] and [[dragonfly]] larvae feed on bottom-dwelling mayfly nymphs, as do aquatic beetles, leeches, crayfish and [[amphibian]]s.<ref name="ThorpRogers2014">{{cite book |last1=Thorp |first1=James H. |last2=Rogers |first2=D. Christopher |title=Thorp and Covich's Freshwater Invertebrates: Ecology and General Biology |url=https://books.google.com/books?id=LB-OAwAAQBAJ&pg=PA886|date=6 September 2014 |publisher=[[Elsevier]] |isbn=978-0-12-385027-0 |page=886}}</ref> Besides the direct mortality caused by these predators, the behaviour of their potential prey is also affected, with the nymphs' growth rate being slowed by the need to hide rather than feed.<ref name=Hauer/> The nymphs are highly susceptible to [[Water pollution|pollution]] and can be useful in the [[biomonitoring]] of water bodies.<ref name=McCafferty1983/> Once they have emerged, large numbers are preyed on by birds, bats and by other insects, such as ''[[Rhamphomyia longicauda]]''.<ref name=Dominguez/>

Mayfly nymphs may serve as [[Host (biology)|hosts]] for [[parasite]]s such as [[nematode]]s and [[trematodes]]. Some of these affect the nymphs' behaviour in such a way that they become more likely to be predated.<ref>{{cite journal |last1=Vance |first1=Sarah A. |last2=Peckarsky |first2=Barbara L. |year=1997 |title=The effect of mermithid parasitism on predation of nymphal ''Baetis bicaudatus'' (Ephemeroptera) by invertebrates |journal=Oecologia |volume=110 |issue=1 |pages=147–152 |doi=10.1007/s004420050143 |pmid=28307463 |bibcode=1997Oecol.110..147V |s2cid=1164123 }}</ref><ref>{{cite journal |last1=Williams |first1=J. K. |last2=Townsend |first2=C. R. |last3=Poulin |first3=Robert |author3-link=Robert Poulin |year=2001 |title=Mermithid nematode infections and drift in the mayfly ''Deleatidium'' spp. (Ephemeroptera). |journal=Journal of Parasitology |volume=87 |issue=5 |pages=1225–1227 |doi=10.1645/0022-3395(2001)087[1225:MNIADI]2.0.CO;2 |pmid=11695410 |s2cid=24933760 }}</ref> Other nematodes turn adult male mayflies into quasi-females which haunt the edges of streams, enabling the parasites to break their way out into the aqueous environment they need to complete their life cycles.<ref name=Zimmer>{{cite book |last=Zimmer |first=Carl |title=Parasite Rex: Inside the Bizarre World of Nature's Most Dangerous Creatures |url=https://books.google.com/books?id=cHe5U83nvwcC&pg=PA84 |year=2003 |publisher=Arrow |isbn=978-0-09-945799-2 |pages=84–86}}</ref> The nymphs can also serve as [[intermediate hosts]] for the horsehair worm ''[[Paragordius varius]]'', which causes its [[definitive host]], a [[grasshopper]], to jump into water and drown.<ref>{{cite book|author1=Goater, Timothy M.|author2=Goater, Cameron P.|author3=Esch, Gerald W.|title=Parasitism: The Diversity and Ecology of Animal Parasites |url=https://books.google.com/books?id=zdtRAgAAQBAJ&pg=PA248 |year=2013 |publisher=[[Cambridge University Press]] |isbn=978-1-107-64961-3 |page=248}}</ref>

==== Effects on ecosystem functioning ====

Mayflies are involved in both [[primary production]] and [[bioturbation]]. A study in laboratory simulated streams revealed that the mayfly genus ''[[Centroptilum]]'' increased the export of [[periphyton]],<ref>{{Cite journal|title = Effects of Three Herbivores on Periphyton Communities in Laboratory Streams|journal = Journal of the North American Benthological Society|date = 1987-06-01|issn = 0887-3593|pages = 92–104|volume = 6|issue = 2|doi = 10.2307/1467219|first1 = Gary A.|last1 = Lamberti|first2 = Linda R.|last2 = Ashkenas|first3 = Stan V.|last3 = Gregory|first4 = Alan D.|last4 = Steinman|jstor = 1467219|s2cid = 54578281}}</ref> thus indirectly affecting primary production positively, which is an essential process for ecosystems. The mayfly can also reallocate and alter the nutrient availability in aquatic habitats through the process of bioturbation. By burrowing in the bottom of lakes and redistributing nutrients, mayflies indirectly regulate phytoplankton and epibenthic primary production.<ref>{{Cite journal |last1 = Bachteram |first1 = André M. |last2 = Mazurek |first2 = Kerry A. |last3 = Ciborowsk |first3 = Jan J. H. |title = Sediment Suspension by Burrowing Mayflies (Hexagenia spp., Ephemeroptera: Ephemeridae)|journal = Journal of Great Lakes Research|date = 2005-01-01|pages = 208–222|volume = 31 |issue=Supplement 2|series = Lake Erie Trophic Status Collaborative Study |doi = 10.1016/S0380-1330(05)70315-4}}</ref> Once burrowing to the bottom of the lake, mayfly nymphs begin to billow their respiratory gills. This motion creates current that carries food particles through the burrow and allows the nymph to filter feed. Other mayfly nymphs possess elaborate filter feeding mechanisms like that of the genus ''[[Isonychia]]''. The nymph have forelegs that contain long bristle-like structures that have two rows of hairs. Interlocking hairs form the filter by which the insect traps food particles. The action of filter feeding has a small impact on water purification but an even larger impact on the convergence of small particulate matter into matter of a more complex form that goes on to benefit consumers later in the food chain.<ref>{{Cite journal |last1=Merritt |first1=Richard W. |last2=Wallace |first2=J. Bruce |date=April 1981 |title=Filter-feeding Insects |journal=Scientific American |volume=244 |issue=4 |pages=132–136, 141–142, 144 |url=http://coweeta.uga.edu/publications/671.pdf |doi=10.1038/scientificamerican0481-132 |bibcode=1981SciAm.244d.132M |access-date=2017-01-08|archive-date=2010-06-12 |archive-url=https://web.archive.org/web/20100612033203/http://coweeta.uga.edu/publications/671.pdf}}</ref>