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Taxonomy

Common Name: PEARLYMUSSEL, CURTIS

Phylum: MOLLUSCA

Class: BIVALVIA

Order: UNIONOIDA

Family: UNIONIDAE

Genus: EPIOBLASMA

Species: CURTISI

Taxonomic Authority: (UTTERBACK)

Taxonomy References: 015 , 002

Status

FEDERAL ENDANGERED
INDICATOR
NONGAME
SENSITIVE
STATE ENDANGERED
STATE RANK S1
GLOBAL RANK G1T1

Status References: 001 , 003 , 004 , 009 , 010 , 011

Habitat Summary

"Inhabit creeks and streams with shallow (less than 36 inches) flowing water and a stable substrate."

Primary Habitat: "Aquatic - river/stream"

References: 001

Distribution

General Occurrence in State:

"Occurs in the Black, castor, and Little Black rivers and in Cane Creek *01,06 08,09*."

County Occurance

County Occurence
Known	Likely	Unknown	Not Likely	Historic	Extirpated
BOLLINGER			ADAIR
BUTLER			ANDREW
RIPLEY			ATCHISON
WAYNE			AUDRAIN
			BARRY
			BARTON
			BATES
			BENTON
			BOONE
			BUCHANAN
			CALDWELL
			CALLAWAY
			CAMDEN
			CAPE GIRARDEAU
			CARROLL
			CARTER
			CASS
			CEDAR
			CHARITON
			CHRISTIAN
			CLARK
			CLAY
			CLINTON
			COLE
			COOPER
			CRAWFORD
			DADE
			DALLAS
			DAVIESS
			DEKALB
			DENT
			DOUGLAS
			DUNKLIN
			FRANKLIN
			GASCONADE
			GENTRY
			GREENE
			GRUNDY
			HARRISON
			HENRY
			HICKORY
			HOLT
			HOWARD
			HOWELL
			IRON
			JACKSON
			JASPER
			JEFFERSON
			JOHNSON
			KNOX
			LACLEDE
			LAFAYETTE
			LAWRENCE
			LEWIS
			LINCOLN
			LINN
			LIVINGSTON
			MACON
			MADISON
			MARIES
			MARION
			MCDONALD
			MERCER
			MILLER
			MISSISSIPPI
			MONITEAU
			MONROE
			MONTGOMERY
			MORGAN
			NEW MADRID
			NEWTON
			NODAWAY
			OREGON
			OSAGE
			OZARK
			PEMISCOT
			PERRY
			PETTIS
			PHELPS
			PIKE
			PLATTE
			POLK
			PULASKI
			PUTNAM
			RALLS
			RANDOLPH
			RAY
			REYNOLDS
			SALINE
			SCHUYLER
			SCOTLAND
			SCOTT
			SHANNON
			SHELBY
			ST. CHARLES
			ST. CLAIR
			ST. FRANCOIS
			ST. LOUIS
			STE. GENEVIEVE
			STODDARD
			STONE
			SULLIVAN
			TANEY
			TEXAS
			VERNON
			WARREN
			WASHINGTON
			WEBSTER
			WORTH
			WRIGHT

References for distribution: 001 , 006 , 008 , 009

Distribution by Watersheds

Castor R. and Castor R. Diversion Channel
Black R.
Current R.

Comments: ""

Distribution by Ecoregions

Mississippi River Alluvial Plains, Ozark Highlands

Comments: ""

Distribution by Potential Natural Vegetation

Oak-Hickory Forest
Oak-Hickory-Pine Forest
Southern Floodplain Forest

Distribution by Natural Divisions of Missouri

Ozark Border: Mississippi River
Ozark: Lower Ozark
Mississippi Lowlands: Lowlands

Habitat Associations

Species is associated with "Aquatic" habitats.

National Wetlands Inventory Association:

Riverine

Aquatic Associations:

"See Comments"
"Riverine, upper perennial", "Rock bottom, boulder",
"Riverine, upper perennial", "Unconsolidated bottom, cobble/gravel",
"Riverine, upper perennial", "Unconsolidated bottom, sand",

References for Aquatic Associations: 001 , 006

Habitat Types:

Permanent Stream

References for Habitat Types: 001

Terrestrial Natural Communities:

References for Terrestrial Natural Communities:

Food Habits

Trophic Level:

"Omnivore"

Larval Food Habits

Other food habits; Not Specified

Comments for larval food habits:
"Parasitic, absorb nutrients from host (host unknown, probably fi"

References for larval food habits: 001

Juvenile Food Habits

Other food habits; Not Specified
Other Microorganisms; Not Specified

Comments for Juvenile Food Habits:
"Parasitic, absorb nutrients from host (host unknown, probably fi"

References Juvenile Food Habits 001

Adult Food Habits

Algae; Not Specified
Protozoans; Not Specified
Other Microorganisms; Not Specified
Bacillariophyceae (diatoms); Not Specified

Comments for Adult Food Habits:
""

References Adult Food Habits 001 , 012

Niche Requirements

Egg Niche Requirements

References for egg niches requirements:

Feeding Larvae Niche Requirements

Substrate (not bottom type): animal substrate
Relation to substrate: occurs in substrate (penetrating)
Host specified in comments(00680)

References for feeding larvae niche requirements: 001 , 006 , 011

Resting Larvae Niche Requirements

Dissolved oxygen: needs high O2 concentrations - saturated (euoxyphilous)
Ph: prefers ph above 7.0 (alkaliphilous)
Turbidity: clear water
Siltation: low
Nutrient concentrations: prefers moderate nutrient concentrations (mesotrophic)
Water quality: restricted to clean waters that have not been exposed to pollution (saprophobic)
Substrate (not bottom type): sand substrate
Substrate (not bottom type): rock substrate
Relation to substrate: occurs in substrate (penetrating)
Bottom type: sand
Bottom type: pebble
Bottom type: gravel
Bottom type: rubble
Bottom type: boulders
Stability of bottom: stable
Gradient specified in comments(00140)
Current velocity: no noticable current
Current velocity specified in comments(00150)
Water level: permanently flooded
Salinity: prefers salt concentrations less than 500 mg/l (0.5 ppt)(oligohalobous)
Water depth specified in comments(00230)
Elevation specified in comments(00240)
Inland wetlands: permanent stream
Stream order: fourth order stream
Stream order: fifth order stream
Stream order: sixth order stream
Stream order: seventh order stream
General habitat association specified in comments(00270)
Natural features: riffles
Natural features: runs or raceways
Natural features specified in comments(00280)

References for resting Larvae niche requirements: 001 , 006 , 011

Feeding Juvenile Niche Requirements

Dissolved oxygen: needs high O2 concentrations - saturated (euoxyphilous)
Ph: prefers ph above 7.0 (alkaliphilous)
Turbidity: clear water
Siltation: low
Nutrient concentrations: prefers moderate nutrient concentrations (mesotrophic)
Water quality: restricted to clean waters that have not been exposed to pollution (saprophobic)
Substrate specified in comments(00080)
Relation to substrate: occurs in substrate (penetrating)
Bottom type: sand
Bottom type: pebble
Bottom type: gravel
Bottom type: rubble
Bottom type: boulders
Stability of bottom: stable
Gradient specified in comments(00140)
Current velocity: no noticable current
Current velocity specified in comments(00150)
Water level: permanently flooded
Salinity: prefers salt concentrations less than 500 mg/l (0.5 ppt)(oligohalobous)
Water depth specified in comments(00230)
Inland wetlands: permanent stream
Stream order: fourth order stream
Stream order: fifth order stream
Stream order: sixth order stream
Stream order: seventh order stream
Natural features: riffles
Host specified in comments(00680)

References for feeding juvenile niche requirements: 001 , 006

Resting Juvenile Niche Requirements

References for resting juvenile niche requirements: 001 , 006

Breeding Adult Niche Requirements

Dissolved oxygen: needs high O2 concentrations - saturated (euoxyphilous)
Ph: prefers ph above 7.0 (alkaliphilous)
Turbidity: clear water
Siltation: low
Nutrient concentrations: prefers moderate nutrient concentrations (mesotrophic)
Water quality: restricted to clean waters that have not been exposed to pollution (saprophobic)
Substrate (not bottom type): sand substrate
Substrate (not bottom type): rock substrate
Relation to substrate: occurs in substrate (penetrating)
Bottom type: sand
Bottom type: pebble
Bottom type: gravel
Bottom type: rubble
Bottom type: boulders
Stability of bottom: stable
Gradient specified in comments(00140)
Current velocity: no noticable current
Current velocity specified in comments(00150)
Water level: permanently flooded
Salinity: prefers salt concentrations less than 500 mg/l (0.5 ppt)(oligohalobous)
Water depth specified in comments(00230)
Elevation specified in comments(00240)
Inland wetlands: permanent stream
Stream order: fourth order stream
Stream order: fifth order stream
Stream order: sixth order stream
Stream order: seventh order stream
Natural features: riffles
Natural features: runs or raceways

References for feeding Adult niche requirements: 001 , 006

Feeding Adult Niche Requirements

References for feeding adult niche requirements: 001 , 006 , 008 , 009

Resting Adult Niche Requirements

References for resting adult niche requirements: 001 , 006 , 008 , 009

Niche Requirement Summary

Bottom type: boulders
Bottom type: gravel
Bottom type: pebble
Bottom type: rubble
Bottom type: sand
Current velocity specified in comments(00150)
Current velocity: no noticable current
Dissolved oxygen: needs high O2 concentrations - saturated (euoxyphilous)
Elevation specified in comments(00240)
General habitat association specified in comments(00270)
Gradient specified in comments(00140)
Host specified in comments(00680)
Inland wetlands: permanent stream
Natural features specified in comments(00280)
Natural features: riffles
Natural features: runs or raceways
Nutrient concentrations: prefers moderate nutrient concentrations (mesotrophic)
Ph: prefers ph above 7.0 (alkaliphilous)
Relation to substrate: occurs in substrate (penetrating)
Salinity: prefers salt concentrations less than 500 mg/l (0.5 ppt)(oligohalobous)
Siltation: low
Stability of bottom: stable
Stream order: fifth order stream
Stream order: fourth order stream
Stream order: seventh order stream
Stream order: sixth order stream
Substrate (not bottom type): animal substrate
Substrate (not bottom type): rock substrate
Substrate (not bottom type): sand substrate
Substrate specified in comments(00080)
Turbidity: clear water
Water depth specified in comments(00230)
Water level: permanently flooded
Water quality: restricted to clean waters that have not been exposed to pollution (saprophobic)

Comments about Life History:

Code	Comment
024	In 1 study, a sample of 23 ind. Included 3 males and 20 females 01
003	May be found with elliptio dilatata, pleurobema coccineum, ptychobranchus occidentalis, lampsilis reeviana brevicula, and fusconaia flava 06
006	Filter water just above stream bottom 01
007	Breed during late summer and fall 01
008	Males release sperm into water, females pick up sperm while filtering 01
017	Incubation period varies from 1 week to several months 01
018	Female releases 70,000 -300,000 glochidia per season 01
020	Eggs are fertilized and develop into glochidia in gills of female 01
030	Most active in spring, summer, and fall 01
034	Limited by availability of suitable habitat and presence of host species 01
035	Regulatory factors include predation 01
099	After glochidia are released from female, they attach to host (probably rainbow darter 11, remain on host until metamorphosis to juvenile stage, juveniles leave host 01
037	Depend on host for dispersal 01

Life History Information

Dispersion: clumped dispersion
Periodicity specified in comments(030)
Limiting factors specified in comments(034)
Regulatory factors specified in comments(035)
Dispersal specified in comments(037)
Other life history information specified in comments(099)
Origin in state: native
Seasonal distribution in state: all seasons
Closely associated plant or animal species specified in comments(003)
Foraging strategy: filtering
Foraging sites: water
Foraging height specified in comments(006)
Breeding season specified in comments(007)
Mating system specified in comments(008)
Duration of pair bond: no pair bond formed
Spawning site: flowing water
Gestation/incubation period specified in comments(017)
Clutch/litter size specified in comments(018)
Development of young at birth/hatching specified in comments(020)
Parental care of young: no care
Sex ratio specified in comments(024)

Comments about Life History:

Code	Comment
024	In 1 study, a sample of 23 ind. Included 3 males and 20 females 01
003	May be found with elliptio dilatata, pleurobema coccineum, ptychobranchus occidentalis, lampsilis reeviana brevicula, and fusconaia flava 06
006	Filter water just above stream bottom 01
007	Breed during late summer and fall 01
008	Males release sperm into water, females pick up sperm while filtering 01
017	Incubation period varies from 1 week to several months 01
018	Female releases 70,000 -300,000 glochidia per season 01
020	Eggs are fertilized and develop into glochidia in gills of female 01
030	Most active in spring, summer, and fall 01
034	Limited by availability of suitable habitat and presence of host species 01
035	Regulatory factors include predation 01
099	After glochidia are released from female, they attach to host (probably rainbow darter 11, remain on host until metamorphosis to juvenile stage, juveniles leave host 01
037	Depend on host for dispersal 01

References for life history: 001 , 006 , 008 , 009 , 011

Management

Beneficial Management Practices:

Regulate harvest of species being described
Shrub/brush - control erosion
Water - develop/maintain spawning/nesting facilities
Water - control sedimentation
Water - control pollution (thermal, physical, chemical)
Water - develop/maintain streamside vegetation
Water - stabilize streambanks
Water - exclude livestock from water
Water - restrict human disturbance
Agricultural - control erosion
Forest - control erosion
Grassland - control erosion

Beneficial Management References: 001 , 008 , 009

Adverse Managment Practices:

Water - application of herbicides
Water - application of pesticides
Water - application of insecticides
Water - application of fertilizer - organic
Water - application of fertilizer - inorganic
Water - dredging and filling
Water - navigational improvements (channelization, dams, locks)
Water - stream channelization
Water - gravel dredging in streams

Adverse Management References: 001 , 008 , 009 , 011

Comments on Management:
Important to protect habitat, especially the Upper Little Black river, stream miles 33.6 - 39.7 *01*. Habitat alteration is the principal threat to this species *09*

References for Management Comments: 001 , 009

References

Reference Code	Citation
001	Unpb Buchanan, A.C. Mo Dept. Of Conservation, 1110 S. College Ave., Columbia, Mo 65201. (573-882-9880).
002	Morton, J. E. 1967. Molluscs (4th Ed). Hutchinson and Co., Ltd. London. 244 Pp.
003	U.S. Dept. Of The Interior. 1980. Republication Of Lists Of Endangered And Threatened Species And Correction Of Technical Errors In Final Rules. U.S. Fws, Washington, D.C. Fed. Register 45(99): 33768-33781.
004	The Wildlife Code of Missouri. Missouri Department of Conservation, P.O. Box 180, Jefferson City, MO 65102. 573-751-4115.
005	Thom, R.H. and J.H. Wilson. 1980 The Natural Divisions Of Missouri. Trans. Mo Acad. Sci. 14:9-24.
006	Unpb Buchanan, A.C. 1982. A Study Of Epioblasma Florentina Curtisi (Utterback 1915), The Curtis Pearly Mussel, In The Upper Little Black River, Missouri. Mo Dept. Of Conservation, 1110 S. College Ave., Columbia, Mo 65201. (573-882-9880).
007	Johnson, R.I. 1978. Systematics And Zoogeography Of Plagiold (= Dysnomia = Epioblasma), An Almost Extinct Genera Of Freshwater Mussels (Bivalvia: Unionidae) From Middle North America. Bull. Mus. Coop. Zool. 148(6): 239-321.
008	Buchanan, A.C. 1983. Distribution, Abundance, Status, And Habitat Of The Curtis' Pearly Mussel, Epioblasma Florentina Curtisi In Southern Missouri. Mo Dept. Of Conservation Endangered Species Project Se-3-1. 10 Pp.
009	U.S. Fish and Wildl. Service. 1986. Curtis' Pearly Mussel Recovery Plan. U.S. Fish and Wildl. Serv., Twin Cities, Mn. 92 Pp.
010	Missouri Natural Heritage Program. 2004. Missouri Species and Communities of Conservation Concern Checklist. Missouri Department Of Conservation. Jefferson City, Missouri. 47 Pp.
011	Missouri Dept. Of Conservation. Best Management Practices: Curtis Pearlymussel. Mo Dept. Of Conservation, Jefferson City, Mo.
012	Allen, W.R. 1914. The Food And Feeding Habits Of Freshwater Mussels. Biol. Bull. 27(3):127-139.
013	Unpb Sternburg, J. MO Dept. of Conservation, P.O. Box 180, Jefferson City, MO 65102 (573-751-4115)
014	Pflieger, W.L. 1989. Aquatic Community Classification System For Missouri. Mo Dept. Of Conservation. Aquatic Series No. 19. 70 Pp + Supplement.
015	Freshwater Mollusk Conservation Society (FMCS). 2021. The 2021 checklist of freshwater mussels. https://molluskconservation.org/Library/Committees/Names/Appendix_1_Bivalves_Revised_Names_List_20210825.pdf.