Dromus dromas

{{Short description|Species of bivalve}} {{Speciesbox | image = Dromus dromas.jpg | image_caption = | status = CR | status_system = IUCN2.3 | status_ref = <ref name="iucn status 17 November 2021">{{cite iucn |author=Bogan, A.E. |date=1996 |title=''Dromus dromas'' |volume=1996 |article-number=e.T6843A12810304 |doi=10.2305/IUCN.UK.1996.RLTS.T6843A12810304.en |access-date=17 November 2021}}</ref> | status2 = CITES_A1 | status2_system = CITES | status2_ref = <ref>{{Cite web|title=Appendices {{!}} CITES|url=https://cites.org/eng/app/appendices.php|access-date=2022-01-14|website=cites.org}}</ref> | genus = Dromus | parent_authority = Simpson, 1900 | display_parents = 2 | species = dromas | authority = ([[Isaac Lea|I. Lea]], 1834) | synonyms = *''Dromus dromas dromas'' (Lea, 1834) *''Dromus dromas caperatus'' (Lea, 1845) *''Unio dromas'' Lea, 1834 *''Unio caperatus'' Lea, 1845 *''Unio abacoides'' Haldeman, 1846 |synonyms_ref=<ref>{{ITIS|taxon=''Dromus dromas'' (Lea, 1834)|id=80245|access-date=20 April 2023}}</ref> }}

'''''Dromus dromas''''', the '''dromedary pearlymussel''' or '''dromedary naiad''', is a rare [[species]] of [[freshwater mussel]] in the family [[Unionidae]]. This [[Aquatic animal|aquatic]] [[bivalve]] [[mollusk]] is native to the [[Cumberland River|Cumberland]] and [[Tennessee River]] systems in the United States, where it has experienced a large population decline. It is a federally listed [[endangered species]] of the United States.<ref name=ecos>{{cite web|url=https://ecos.fws.gov/ecp/species/6377|title=Dromedary pearlymussel (''Dromus dromas'')|website=Environmental Conservation Online System|publisher=U.S. Fish & Wildlife Service|access-date=20 April 2023}}</ref><ref>{{Federal Register|41|24062}}</ref>{{rp|24064}}

This mussel is yellow-green in color with interrupted green rays on the shell. The [[nacre]] is white, pink, or reddish. The species got its name from the distinctive hump on the shell of larger individuals.<ref name=ahlstedt>{{cite report|url=https://ecos.fws.gov/docs/recovery_plan/840709c.pdf|title=Recovery Plan for the Dromedary Pearly Mussel: ''Dromus dromas'' (Lea, 1834), ''Dromus dromas form caperatus'' (Lea, 1845)|date=November 1983|last=Ahlstedt|first=Steven|publisher=U.S. Fish and Wildlife Service, Southeast Region|location=Atlanta, Georgia|access-date=20 April 2023}}</ref> A "headwaters form," ''D. dromas'' form ''caperatus'' (Lea, 1845) has additionally been described.<ref name=ahlstedt/>{{rp|9-10}}

This species lives in clear, clean, fast-flowing water. It cannot tolerate water of poor quality, for example, water with [[silt]].<ref name=tnc>{{cite web|url=https://explorer.natureserve.org/Taxon/ELEMENT_GLOBAL.2.110730/Dromus_dromas|title=''Dromus dromas''|website=NatureServe Network Biodiversity Location Data accessed through NatureServe Explorer|publisher=NatureServe|author=NatureServe|date=7 April 2023|access-date=20 April 2023|location=Arlington, Virginia}}</ref>

Like other freshwater mussels, this species reproduces by releasing larvae called [[glochidium|glochidia]] into the water. The glochidia are eaten by fish and lodge in the fish's gills, where they develop into juvenile mussels. Fish hosts for this mussel species include [[Cottus baileyi|black sculpin]] (''Cottus baileyi''), [[Etheostoma blennioides|greenside darter]] (''Etheostoma blennioides''), [[Etheostoma flabellare|fantail darter]] (''Etheostoma flabellare''), [[Etheostoma simoterum|snubnose darter]] (''Etheostoma simoterum''), [[Percina aurantiaca|tangerine darter]] (''Percina aurantiaca''), [[Percina burtoni|blotchside logperch]] (''Percina burtoni''), [[Percina caprodes|logperch]] (''Percina caprodes''), [[Percina copelandi|channel darter]] (''Percina copelandi''), [[Percina evides|gilt darter]] (''Percina evides''), and [[Percina roanoka|Roanoke darter]] (''Percina roanoka'').

This species was historically one of the most common mussels in the Tennessee and Cumberland rivers.<ref name=ahlstedt/>{{rp|2-3}} In 1978, however, only three living specimens could be found during a Tennessee River survey, all from the [[Chickamauga Lake|Chickamauga Reservoir]].<ref name=ahlstedt/>{{rp|3}} Similarly, two live individuals were found in a Cumberland River survey in 1976, with another individual located in a commercial mussel fisherman's boat, while dead specimens were found at a rock-quarry clammer's camp.<ref name=ahlstedt/>{{rp|3,5}} Today, the species has been reduced to no more than four populations (two of which are experimental and non-essential).<ref name=ecos/><ref name=5year2020>{{cite web|url=https://ecos.fws.gov/docs/tess/species_nonpublish/2959.pdf|title=Dromedary Pearlymussel ''Dromus dromas'' (Lea, 1834) 5-Year Review: Summary and Evaluation|publisher=U.S. Fish and Wildlife Service Southeast Region Tennessee Ecological Services Field Office|location=Cookeville, Tennessee|access-date=20 April 2023|year=2020}}</ref> It has been [[extirpated]] from the wild in the state of [[Alabama]], but it has been reintroduced there (experimental population).<ref name=ecos/> The only remaining reproducing populations occur in the [[Clinch River|Clinch]] and [[Powell River (Tennessee River)|Powell Rivers]].<ref name=tnc/> Reproducing populations remain in under 10% of the mussel's historical range, and the populations are disjunct.<ref name=jones>Jones, J. W., et al. (2004). [http://fishwild.vt.edu/mussel/PDFfiles/jonesetal.pdf Life history and propagation of the endangered dromedary pearlymussel (''Dromus dromas'') (Bivalvia: Unionidae).] {{Webarchive|url=https://web.archive.org/web/20120322235952/http://fishwild.vt.edu/mussel/PDFfiles/jonesetal.pdf |date=2012-03-22 }} ''J N Am Benthol Soc'' 23(3) 515-25.</ref>

Factors contributing to its decline include the [[dam|impoundment]] of waterways, increased silt, and pollution from [[sewage]], [[coal mining]], and [[petroleum exploration|oil and gas drilling]].<ref name=tnc/>

Between 2016 and 2019, mass die-offs of ''D. dromas'', possibly attributable to viral diseases, occurred in the Clinch River population.<ref name=5year2020/>{{rp|11}}

==References== {{Reflist}}

[[Category:Molluscs of the United States]] [[Category:Unionidae]] [[Category:Bivalves described in 1834]] [[Category:ESA endangered species]] [[Category:Taxonomy articles created by Polbot]] [[Category:Taxa named by Isaac Lea]]