(DRAFT) - Taxonomy
Species MUSSEL, MARSHALL'S
Species Id ESIS404023
Date 13 MAR 96

TAXONOMY

NAME - MUSSEL, MARSHALL'S

OTHER COMMON NAMES - MUSSEL, MARSHALL'S; PIGTOE, ROUND, SOUTHERN;PIGTOE, FLAT; MUSSEL, PIGTOE, ROUND and SOUTHERN

ELEMENT CODE -

CATEGORY - Aquatic Molluscs

PHYLUM AND SUBPHYLUM - MOLLUSCA,

CLASS AND SUBCLASS - BIVALVIA,

ORDER AND SUBORDER - UNIONOIDA,

FAMILY AND SUBFAMILY - UNIONIDAE,

GENUS AND SUBGENUS - PLEUROBEMA,

SPECIES AND SSP - MARSHALLI,

SCIENTIFIC NAME - PLEUROBEMA MARSHALLI

AUTHORITY -

TAXONOMY REFERENCES -

COMMENTS ON TAXONOMY -
Marshall's Mussel

Pleurobema marshalli Frierson, 1927

KINGDOM: Animal GROUP: Clam

PHYLUM: Mollusca CLASS: Bivalvia
ORDER: Unionoida FAMILY: Unionidae

Marshall's mussel, Pleurobema marshalli, is a bivalve mollusk
about 60 mm long, 50 mm high, and 30 mm wide. The shell has a shallow
umbonal cavity, a rounded sub-ovate or obliquely elliptical outline,
nearly terminal beaks, and very low pustules or welts on the
postventral surface (01).
The species may be referred to as the Flat pigtoe (04), southern
round pigtoe mussel, or southern round pigtoe.
Frierson's collection (type material) was purchased by the
University of Michigan Museum of Zoology according to Stansbery (01).
Cotypes have been presented to the Academy of Natural Sciences of
Philadelphia (01). Drawings can be found in Stansbery (01).

Taxonomy - 1 (DRAFT) - Status
Species MUSSEL, MARSHALL'S
Species Id ESIS404023
Date 13 MAR 96

STATUS

Coded Status
Alabama; Federal Endangered
Alabama; Unofficially Listed
Mississippi; Federal Endangered
Mississippi; State Recognized

E: Federal Endangered

Commercial

COMMENTS ON STATUS -
U.S. STATUSES AND LAWS:
The Marshall's mussel (Pleurobema marshalli) has been designated
an Endangered species pursuant to the Endangered Species Act of 1973
(50 CFR 17.11; P.L. 93-205, 87 Stat. 884; 16 U.S.C. 1531-1540), as
amended. The species has this status wherever found including the
States of AL and MS. Critical Habitat has not been designated.
This species is protected by the Lacey Act (P.L. 97-79, as
amended; 16 U.S.C. 3371 et seq.) which makes it unlawful to import,
export, transport, sell, receive, acquire, or purchase any wild animal
(alive or dead including parts, products, eggs, or offspring):
(1) in interstate or foreign commerce if taken, possessed,
transported or sold in violation of any State law or
regulation, or foreign law; or
(2) if taken or possessed in violation of any U.S. law,
treaty, or regulation or in violation of Indian tribal law.
It is also unlawful to possess any wild animal (alive or dead
including parts, products, eggs, and offspring) within the U.S.
territorial or special maritime jurisdiction (as defined in
18 U.S.C. 7) that is taken, possessed, transported, or sold in
violation of any State law or regulation, foreign law, or Indian
tribal law.

RESPONSIBLE FEDERAL AGENCIES:

USFWS -Responsible for the management/recovery, listing, and
law enforcement/protection of this species.

All Federal agencies have responsibility to ensure that any
action authorized, funded, or carried out by that agency is not likely
to jeopardize the continued existence of the species or result in the
destruction or adverse modification of Critical Habitat (50 CFR 402),
and to utilize their authorities to carry out programs for the
conservation of the species.

STATE STATUSES AND LAWS:

STATE: Alabama
UNOFFICIAL LIST: Endangered, Bulletin No. 2, "Endangered and
Threatened Plants and Animals of Alabama",
Status - 1 (DRAFT) - Status
Species MUSSEL, MARSHALL'S
Species Id ESIS404023
Date 13 MAR 96

Alabama Museum of Natural History.

STATE: Mississippi
DESIGNATED STATUS: Recognized Endangered
ADMINISTRATIVE AGENCY: MS Dept. of Wildlife Conservation
STATE STATUTE: Public Notice No 2156, Effective Sept. 1, 1981.

INTERNATIONAL STATUSES, TREATIES, AND AGREEMENTS:
Pleurobema marshalli, Marshall's mussel, is listed as endangered
in the 1986 IUCN Red List of Threatened Animals.

ECONOMIC STATUSES:
The species may have some value in the cultured pearl industry.

79/05/01:44 FR 25589/ - Notice of review
80/04/11:45 FR 24904/24905 - Notice of review
84/05/22:49 FR 21664/21675 - Notice of review
86/04/07:51 FR 11761/11768 - Proposed rule
86/06/18:51 FR 22092/ - Notice of public hearing
87/04/07:52 FR 11162/11169 - Final rule, listed as Endangered

Status - 2 HABITAT ASSOCIATIONS

HABITAT - AQUATIC
INLAND AQUATIC

LAND USE -
Streams and Canals

NATIONAL WETLAND INVENTORY CODES

NWI NWICLS NWIMOD NWISPEC

Riverine, upper perennial SB2
Riverine, upper perennial SB1

COMMENTS ON HABITAT ASSOCIATIONS -
Marshall's mussel (Pleurobema marshalli) is found associated with
a riffle-run habitat. Williams found it in the main channel in gravel
or sandy-gravel in moderate to swift current. It does better in
stable substrates in strong current (01). Specific environmental
parameters required by adults are unknown.
Habitat of the glochidia is initially within the gills of the
female, then in the water column, and finally attached to a suitable
fish host. The host species is unknown. Any alteration of these life
stage-specific habitats during its life cycle would likely affect the
long-term success of a population. Habitat requirements or
associations for the juvenile stage are unknown.

Habitat Associations - 1 (DRAFT) - Food Habits
Species MUSSEL, MARSHALL'S
Species Id ESIS404023
Date 13 MAR 96

FOOD HABITS

TROPHIC LEVEL -
OMNIVORE

LIFESTAGE FOOD FOOD PART
General Detritus
General Bacteria
General Phytoplankton
General Diatoms
General Zooplankton
General Fish

Food Habits - 1 (DRAFT) - Environment Associations
Species MUSSEL, MARSHALL'S
Species Id ESIS404023
Date 13 MAR 96

ENVIRONMENTAL ASSOCIATIONS

G = General A = Adult
LIM = Limiting RA = Resting Adult
J = Juvenile FA = Feeding Adult
RJ = Resting Juvenile BA = Breeding Adult
FJ = Feeding Juvenile P = Pupae
L = Larvae E = Egg
RL = Resting Larvae
FL = Feeding Larvae

LIFESTAGE ENVIRONMENTAL ASSOCIATIONS
G Aquatic Features: Pool areas

Environment Associations - 1 (DRAFT) - Life History
Species MUSSEL, MARSHALL'S
Species Id ESIS404023
Date 13 MAR 96

LIFE HISTORY

FOOD HABITS:
Glochidia are probably obligate parasites on the tissues of the
gills or fins of fish. Adult Pleurobema marshalli are filter-feeders
and consume particulate matter suspended in the water column.
Identifiable stomach contents almost invariably include detritus,
bacteria, phytoplankton, diatoms, and zooplankters (02). No study of
the food habits of adult P. marshalli has been conducted; specific
required/preferred foods are therefore unknown.

HOME RANGE/TERRITORY:
Non-territorial. The species is sedentary during its adult life
and generally occurs in rivers with others of its kind.

PERIODICITY:
No known periodicity.

MIGRATION PATTERNS:
Non-migratory.

COVER/SHELTER REQUIREMENTS:
Marshall's mussel requires flowing water, frequently a riffle,
over stable sand and gravel. Water velocity can vary greatly. The
sand and gravel substrate must remain free of any heavy sediment (01).

REPRODUCTIVE SITE REQUIREMENTS:
Water velocity can vary greatly. The sand and gravel substrate
must remain free of any heavy sediment (01). See also Cover/Shelter
Requirements above.

REPRODUCTIVE CHARACTERISTICS:
Sperm are discharged into the surrounding water and dispersed by
water currents. Females downstream from the males obtain sperm during
the normal process of siphoning water while feeding and during
respiration. Fertilization occurs within the gills of females, which
serve as marsupia for embryos developing to the parasitic stage
(glochidia) and are then released (02). The specifics of reproductive
characteristics for this species are unknown.

PARENTAL CARE:
No parental care occurs.

POPULATION BIOLOGY:
No information exists on the population biology of this species.

SPECIES INTERRELATIONSHIPS:
The required fish hosts for the parasitic glochidia of this
species are unknown.

OTHER LIFE HISTORY DESCRIPTORS:
None.

Life History - 1 (DRAFT) - Management Practices
Species MUSSEL, MARSHALL'S
Species Id ESIS404023
Date 13 MAR 96

MANAGEMENT PRACTICES

RESULT MANAGEMENT PRACTICE

Beneficial Maintaining/Controlling Water Flow
Beneficial Land Acquisition
Beneficial Creating Artificial Habitat/Nesting Structure
Adverse Siltation
Existing Siltation
Adverse Water Level Fluctuation
Existing Water Level Fluctuation
Adverse Reservoirs
Existing Reservoirs
Adverse Dredging
Existing Dredging

COMMENTS ON MANAGEMENT PRACTICES -
The decline of Marshall's mussel (Pleurobema marshalli) is
directly related to habitat modification from construction of the
Tennessee-Tombigbee Waterway. The mainstem Tombigbee River from
Columbus, MS, downstream to Epes, AL, once contained this species.
Modification of this river reach by dredging, impoundment (and the
resulting siltation), and cutoffs has eliminated this species from all
known habitats except a bendway below Gainesville Dam, AL (01,03).
Future threats include a small, isolated population susceptible
to numerous environmental perturbations, and a low gene pool for
future reproduction.

UNAPPROVED PLAN:
No recovery plan is yet developed for the Marshall's mussel. Recovery
planning should be initiated in FY 1988.

Recovery actions that are anticipated for the Marshall's mussel
include: Maintaining water flow; creating artificial habitat (e.g.,
gravel bars); prohibiting sand and gravel dredging; and land easement
protection for remaining habitat.
At present, dredging is being prohibited and water flow is being
maintained.

Management Practices - 1 (DRAFT) - References
Species MUSSEL, MARSHALL'S
Species Id ESIS404023
Date 13 MAR 96

References

***** REFERENCES FOR ALL NARRATIVES EXCEPT N-OCCURRENCE *****

01 Stansbery, D.H. 1983. The status of Pleurobema marshalli Frierson
1927 (Mollusca:Bivalvia:Unionoida). Unpublished rep. on file at:
USFWS, Jackson Field Office, Jackson, MS. 10 pp + 6 pp museum
records.
02 U.S. Fish and Wildlife Service. 1984. Recovery Plan for the Rough
Pigtoe Pearly Mussel [Pleurobema plenum (Lea, 1840)]. U.S. Fish
and Wildlife Service, Atlanta, GA. 51 pp.
03 Fuller, S.L.H. 1974. Clams and mussels (Mollusca:Bivalvia).
Pages 215-273. IN: Pollution Ecology of Freshwater Invertebrates.
C.W. Hart and S.L.H. Fuller, eds. Academic Press, NY.
04 Turgeon, D.D., A.E. Bogan, E.V. Coan, W.K. Emerson, et al. 1986.
Mollusks; A list of common and scientific names of aquatic
invertebrates from the United States and Canada. Am. Fish. Soc.
Special Publ., Bethesda, MD. 156 pp.

***** REFERENCES FOR N-OCCURRENCE NARRATIVE ONLY *****

References - 1