View source for Lacy elimia

{{Short description|Species of gastropod}}
{{Speciesbox
| name = Lacy elimia
| image =
| status = VU
| status_system = IUCN2.3
| status_ref = <ref name="iucn status 15 November 2021">{{cite iucn |author=Bogan, A.E. |date=1996 |title=''Elimia crenatella'' |volume=1996 |page=e.T7605A12834630 |doi=10.2305/IUCN.UK.1996.RLTS.T7605A12834630.en |access-date=15 November 2021}}</ref>
| taxon = Elimia crenatella
| authority = [[Isaac Lea|I. Lea]], 1860
}}
The '''lacy elimia''', also known as the '''lacey elimia''', [[scientific name]] '''''Elimia crenatella''''', is a [[species]] of [[freshwater snail]] with a gill and an [[operculum (gastropod)|operculum]], an [[aquatic animal|aquatic]] [[gastropod]] [[mollusk]] in the family [[Pleuroceridae]].
This species is [[Endemism|endemic]] to the [[United States]], specifically the state of [[Alabama]]. The snail has been listed as threatened on the [[United States Fish and Wildlife Service list of endangered species]] since October 28, 1998.<ref>Fish and Wildlife Service. (October 28) 1998. [https://www.federalregister.gov/documents/1998/10/28/98-28884/endangered-and-threatened-wildlife-and-plants-endangered-status-for-three-aquatic-snails-and ''Endangered and Threatened Wildlife and Plants; Endangered Status for Three Aquatic Snails, and Threatened Status for Three Aquatic Snails in the Mobile River Basin of Alabama'']. Federal Register, Vol. 63, No. 208, Rules and Regulations, Accessed 26 January 2009.</ref>
== Description ==
The lacy elimia is a small species in the family Pleuroceridae. Growing to about 1.1 centimeters (cm) (0.4&nbsp;in) in length, the [[gastropod shell|shell]] is conic in shape, strongly striate, and often folded in the upper [[Whorl (mollusc)|whorls]].
The shell color is dark brown to black, often purple in the [[Aperture (mollusc)|aperture]], and without banding. The aperture is small and ovate. The lacy elimia is easily distinguished from other ''[[Elimia]]'' species by a combination of characters (i.e., size, ornamentation, color).<ref name="plan"/>
== Genetics ==
In a recent [[genetic sequence]] study of the [[16S ribosomal RNA]] gene, the lacy elimia was found to be very similar to the compact elimia (''[[Elimia showalteri]]'').<ref name="Lydeard">{{cite journal |last1=Lydeard |first1=Charles |last2=Holznagel |first2=Wallace E. |last3=Garner |first3=Jeff |last4=Hartfield |first4=Paul |last5=Pierson |first5=J.Malcolm |title=A A molecular phylogeny of Mobile River drainage basin pleurocerid snails (Caenogastropoda: Cerithioidea) |journal=Molecular Phylogenetics and Evolution |date=1997 |volume=7 |issue=1 |pages=117–128 |doi=10.1006/mpev.1996.0377}}</ref> Despite their apparent close genetic relationship, the authors made no suggestion that the two species represented a single species. Upon review of Lydeard et al. (1997),<ref name="Lydeard"/> Dillon<ref>Dillon, R.T., Jr. (College of Charleston, Charleston, South Carolina, in litt., 1997) in [[U.S. Fish and Wildlife Service]]. 2005. [http://ecos.fws.gov/docs/recovery_plan/051202.pdf ''Recovery Plan for 6 Mobile River Basin Aquatic Snails'']. U.S. Fish and Wildlife Service, Jackson, Mississippi. 46 pp., page 7.</ref> suggested that additional genetic studies were needed to demonstrate the genetic uniqueness of the lacy elimia. However, the Lydeard et al. (1997)<ref name="Lydeard"/> genetic study addressed only one small genetic character of the [[genome]] (entire genetic make-up of an individual) of these species, and other characters strongly support the taxonomic status of the lacy elimia.
The two species are [[allopatric]] (do not overlap in distribution - the compact elimia occurs in the [[Cahaba River]], whereas the lacy elimia is found in the [[Coosa River]] drainage), and are strikingly different in size, appearance, and behavior. The compact elimia has a large, robust, smooth shell boldly colored brown and/or green, whereas the lacy elimia has a small, delicate, darkly colored, and ornamented shell.
The lacy elimia is one of the few elimia snails in the Basin that does not exhibit [[Cline (biology)|clinal variation]].<ref name="Goodrich 1936">Goodrich C. 1936. ''Goniobasis of the Coosa River, Alabama''. Miscellaneous Publications, Museum of Zoology, University of Michigan (31):1-60.</ref> In addition, compact elimia are found grazing individually throughout shoal habitats, whereas the lacy elimia is usually found in tight clusters or colonies on larger rocks within a shoal.<ref>P. Hartfield, pers. obsv. in [[U.S. Fish and Wildlife Service]]. 2005. [http://ecos.fws.gov/docs/recovery_plan/051202.pdf ''Recovery Plan for 6 Mobile River Basin Aquatic Snails'']. U.S. Fish and Wildlife Service, Jackson, Mississippi. 46 pp., page 7-8.)</ref> Allopatry, morphology, and behavior are strong characters supporting the species status of the lacy elimia.
== Distribution ==
[[File:Map of Alabama highlighting Talladega County.svg|thumb|The current distribution of lacy elimia is in 3 creeks in [[Talladega County, Alabama]]]]
The lacy elimia was historically abundant in the [[Coosa River]] main stem from [[St. Clair County, Alabama]] to [[Chilton County, Alabama]], and was also known in several [[Coosa River#Tributaries|Coosa River tributaries]]: [[Big Will's Creek]], DeKalb County; [[Kelley's Creek]], St. Clair County; and [[Choccolocco Creek]] and [[Tallaseehatchee Creek]], Talladega County, Alabama.<ref name="Goodrich 1936"/>
Currently, the lacy elimia is only known to survive in three Coosa River tributaries: [[Cheaha Creek]], [[Emauhee Creek]], and [[Weewoka Creek]], [[Talladega County, Alabama]].<ref>Bogan, A.E. & J.M. Pierson. 1993. ''Survey of the aquatic gastropods of the Coosa River Basin, Alabama: 1992''. Alabama Natural Heritage Program. Contract Number 1923.</ref> The species is locally abundant in the lower reaches of Cheaha Creek. This stream originates within the [[Talladega National Forest]]; however, no specimens of the lacy elimia have been collected on [[United States Forest Service]] lands. The species has also been found at single sites in Emauhee and Weewoka creeks, where specimens are rare, and difficult to locate.<ref name="plan"/>
All of these streams are variously impacted by sediments and nutrients from a variety of upstream rural, suburban, and/or urban sources. Because of their small sizes and limited flows, their water and habitat quality can be rapidly affected by local and off site pollution sources.<ref name="plan"/>
== Reasons for the decline ==
{{main|Environmental impacts of dams}}
The lacy elimia has disappeared from more than 90 percent of its historic range. The curtailment of habitat and range for this (and few other snail species) species in the [[Mobile River|Mobile]] Basin's larger rivers (Coosa River for lacy elimia) is primarily due to extensive construction of [[dam]]s, and the subsequent [[inundation]] of the snail's shoal habitats by the impounded waters. This snail has disappeared from all portions of its historic habitats that have been impounded by dams.<ref name="plan"/>
Dams change such areas by eliminating or reducing currents, and thus allowing sediments to accumulate on inundated channel habitats. Impounded waters also experience changes in water chemistry, which could affect survival or reproduction of riverine snails. For example, many reservoirs in the Basin currently experience eutrophic (enrichment of a water body with nutrients) conditions, and chronically low dissolved oxygen levels.<ref>Alabama Department of Environmental Management. 1994. ''Water quality report to Congress for calendar years 1992 and 1993''. Montgomery, Alabama. 111 pp.</ref><ref>Alabama Department of Environmental Management (ADEM). 1996. ''Water quality report to Congress for calendar years 1994 and 1995''. Montgomery, Alabama. 144 pp.</ref> Such physical and chemical changes can affect feeding, respiration, and reproduction of these riffle and shoal snail species.<ref name="plan"/>
== Ecology ==
Little is known of the ecology specific to the lacy elimia, however, common information about genus ''Elimia'' are as follows.<ref name="plan"/>
===  Habitat ===
Elimia snails are gill-breathing snails that typically inhabit highly oxygenated waters on rock shoals and gravel bars.<ref name="plan"/>
It is associated with river or stream habitats characterized by flowing currents, and hard, clean bottoms (e.g., bedrock, boulder, gravel).<ref name="Goodrich 1936"/><ref>Goodrich, C. 1922. ''The Anculosae of the Alabama River Drainage''. Miscellaneous Publications, Museum of Zoology, University of Michigan (7):1-57.</ref><ref>Clench, W.J. & R.D. Turner. 1955. ''The North American genus Lioplax in the Family Viviparidae''. Occasional Papers on Mollusks. 2(19):1-20.</ref>
=== Feeding habits ===
Most elimia species graze on [[periphyton]] (attached algae) growing on benthic (bottom) substrates.<ref name="plan"/>
=== Life cycle ===
Individual snails are either male or female. Eggs are laid in early spring and hatch in about 2 weeks. Snails apparently become sexually mature in their first year, but, in some cases, females may not lay eggs until their second year. Some elimia species may live as long as 5 years.<ref>Dillon, R.T., Jr. 1988. ''Evolution from transplants between genetically distinct populations of freshwater snails''. Genetica 76: 111-119.</ref>
==References==
This article incorporates public domain text (a [[public domain]] [[work of the United States Government]]) from the reference.<ref name="plan">[[U.S. Fish and Wildlife Service]]. 2005. [http://ecos.fws.gov/docs/recovery_plan/051202.pdf ''Recovery Plan for 6 Mobile River Basin Aquatic Snails'']. U.S. Fish and Wildlife Service, Jackson, Mississippi. 46 pp.</ref>
{{Reflist}}
{{Taxonbar|from=Q3142739}}
{{DEFAULTSORT:Lacy Elimia}}
[[Category:Elimia]]
[[Category:Endemic molluscs of the United States]]
[[Category:Endemic fauna of Alabama]]
[[Category:Freshwater animals of North America]]
[[Category:Gastropods described in 1860]]
[[Category:Taxonomy articles created by Polbot]]
[[Category:Taxa named by Isaac Lea]]
[[Category:ESA threatened species]]