(DRAFT) - Taxonomy
Species PEARLSHELL, LOUISIANA
Species Id ESIS404026
Date 13 MAR 96
TAXONOMY
NAME - PEARLSHELL, LOUISIANA
OTHER COMMON NAMES - PEARLSHELL, LOUISIANA; PEARLSHELL and MISISSIPPI
ELEMENT CODE -
CATEGORY - Aquatic Molluscs
PHYLUM AND SUBPHYLUM - MOLLUSCA,
CLASS AND SUBCLASS - BIVALVIA,
ORDER AND SUBORDER - UNIONOIDA,
FAMILY AND SUBFAMILY - UNIONIDAE,
GENUS AND SUBGENUS - MARGARITIFERA,
SPECIES AND SSP - HEMBELI,
SCIENTIFIC NAME - MARGARITIFERA HEMBELI
AUTHORITY -
TAXONOMY REFERENCES -
COMMENTS ON TAXONOMY -
Louisiana Pearlshell
Margaritifera hembeli (Conrad, 1838)
KINGDOM: Animal GROUP: Clam
PHYLUM: Mollusca CLASS: Bivalvia
ORDER: Unionoida FAMILY: Unionidae
This mussel is about 100 millimeters (mm) (3.9 inches) long,
50 mm (2.0 inches) high, and 30 mm (1.2 inches) wide. The shell
is generally elliptical with an angular posterior margin, obtuse
undulations on the posterior slope, a dark brown to black
periostracum, with white nacre.
The Louisiana pearlshell was described as Unio hembeli by Conrad
in 1838. This species was placed in the genus Margaron by Lee
(1870), then in Margaritana by Simpson (1900), and finally in
Margaritifera by Athearn (1970). The holotype is cataloged in
the Academy of Natural Sciences in Philadelphia, PA (01).
Taxonomy - 1 (DRAFT) - Status
Species PEARLSHELL, LOUISIANA
Species Id ESIS404026
Date 13 MAR 96
STATUS
Coded Status
Louisiana; Federally Endangered
E: Federal Endangered
Ornamental
COMMENTS ON STATUS -
U.S. STATUSES AND LAWS:
The Louisiana Pearlshell (Margaritifera hembeli) 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 State of Louisiana.
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
(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.
USFS -Responsible for the law enforcement/protection of this
species with applicable State and Federal laws on
public lands under their control. Also responsible
for management/recovery on Forest Service lands. The
Forest Service is responsible for integrating
management, protection, and conservation of Federally
listed species into the Forest Planning process
(36 CFR 219.19 and 219.20).
Management practices that would cause detrimental
changes in water temperature or composition, water
course blockage, or sediment deposits within 100 feet
of the edges of perennial streams, lakes or other
bodies of water are prohibited (36 CFR 219.27(e)).
All Federal agencies have responsibility to ensure that any
action authorized, funded, or carried out by that agency is not likely
Status - 1 (DRAFT) - Status
Species PEARLSHELL, LOUISIANA
Species Id ESIS404026
Date 13 MAR 96
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: Louisiana
DESIGNATED STATUS: none
INTERNATIONAL STATUSES, TREATIES, AND AGREEMENTS:
none
ECONOMIC STATUSES:
Of value to collectors.
87/04/24:52 FR 13794/13797 - Final rule
Status - 2 HABITAT ASSOCIATIONS
HABITAT - AQUATIC
INLAND AQUATIC
SOCIETY OF AMERICAN FORESTRY TYPES
SAF TYPE STAGE CLOSURE
Longleaf Pine mature tree
Shortleaf Pine-Oak mature tree
LAND USE -
Deciduous Forest Land
Evergreen Forest Land
Mixed Forest Land
Streams and Canals
NATIONAL WETLAND INVENTORY CODES
NWI NWICLS NWIMOD NWISPEC
Riverine, upper perennial SB1
Riverine, upper perennial SB
COMMENTS ON HABITAT ASSOCIATIONS -
The preferred habitat is stable sand and gravel substrate in
small, clear flowing streams. Only large individuals seem to
tolerate shifting sand. All of the known population is in stream
stretches within forested areas. The life history and other
environmental requirements of this species are unknown.
Habitat Associations - 1 (DRAFT) - Food Habits
Species PEARLSHELL, LOUISIANA
Species Id ESIS404026
Date 13 MAR 96
FOOD HABITS
TROPHIC LEVEL -
OMNIVORE
LIFESTAGE FOOD FOOD PART
General Detritus
General Bacteria
General Phytoplankton
General Diatoms
General Zooplankton
Food Habits - 1 (DRAFT) - Environment Associations
Species PEARLSHELL, LOUISIANA
Species Id ESIS404026
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 PEARLSHELL, LOUISIANA
Species Id ESIS404026
Date 13 MAR 96
LIFE HISTORY
FOOD HABITS:
Freshwater mussels are filter feeders and do not exhibit a
food preference.
HOME RANGE/TERRITORY:
Non-territorial
PERIODICITY:
No periodicity shown
MIGRATION PATTERNS:
Nonmigratory
COVER/SHELTER REQUIREMENTS:
Occurs in riffles and pools from a few inches up to a foot
deep, provided there is good current.
REPRODUCTIVE SITE REQUIREMENTS:
Require flowing water for gamete dispersal.
REPRODUCTIVE CHARACTERISTICS:
This species is presumed to require a fish host for the
parasitic glochidia. Virtually nothing is known of its
reproductive characteristics.
PARENTAL CARE:
None.
POPULATION BIOLOGY:
The primary current limiting factor is suitable habitat.
The population biology is unknown. Recovery potential depends
upon the success of habitat restoration.
SPECIES INTERRELATIONSHIPS:
This mussel is likely directly dependent upon a fish host
for its parasitic larva. The fish host is unknown.
OTHER LIFE HISTORY DESCRIPTORS:
Life History - 1 (DRAFT) - Management Practices
Species PEARLSHELL, LOUISIANA
Species Id ESIS404026
Date 13 MAR 96
MANAGEMENT PRACTICES
RESULT MANAGEMENT PRACTICE
Beneficial Controlling/Restricting Off-Road Vehicles
Beneficial Maintaining/Controlling Water Flow
Beneficial Controlling pollution [thermal, chemical, physical]
Beneficial Controlling/Restricting Pesticide Use
Beneficial Restricting Timber Harvest
Beneficial Controlling/Restricting Noncommercial Harvest
Beneficial Controlling/Removing Domestic Animals
Adverse Collecting
Existing Collecting
Adverse Off Road Vehicles
Existing Off Road Vehicles
Adverse Inherent Reproductive Characteristics
Existing Inherent Reproductive Characteristics
Adverse Low Gene Pool
Existing Low Gene Pool
Adverse Siltation
Existing Siltation
Adverse Water Level Stabilization
Existing Water Level Stabilization
Adverse Environmental Contamination/Pollution
Existing Environmental Contamination/Pollution
Adverse Erosion
Existing Erosion
Adverse
Existing
Adverse Forest Alteration
Existing Forest Alteration
COMMENTS ON MANAGEMENT PRACTICES -
The scattered occurrence of the species in headwater streams of
the drainage suggests a historic range including most, if not all, of
the Bayou Boeuf headwater systems, and that impoundments have
eliminated populations in intervening areas. This suggested range is
supported by a small population in Brown's Creek of the Bayou Rapides
drainage. Bayou Rapides enters Bayou Boeuf several miles below any
other known population of the Louisiana pearlshell. The species
presently occurs in Mack Branch above Kincaid Reservoir but not in
other streams contributing to this impoundment. Kincaid Reservoir
impounds the uppermost headwaters of Bayou Boeuf. The known good
populations occur in the unimpounded Caster Creek and Bayou Clear
drainages, tributaries to Bayou Boeuf. Other impoundments of the
Bayou Boeuf system that may have affected this species are Indian
Creek Reservoir, Oden Lake, and Cotile Lake (01).
Inundation by beaver dams appears to be a significant threat.
One population of about 1000 individuals found in 1985 by the
Louisiana Heritage survey was later inundated by a beaver pond
(01).
Freshwater mussels are adversely impacted by sediment and
Management Practices - 1 (DRAFT) - Management Practices
Species PEARLSHELL, LOUISIANA
Species Id ESIS404026
Date 13 MAR 96
by unstable substrate. The Bayou Boeuf drainage includes a number
of gravel pits on private lands that contribute to sedimentation,
especially in the Indian Creek drainage. The sedimentation likely
contributed to the elimination of Louisiana pearlshell populations
that could have occurred in this drainage. Habitat within the
Kisatchie National Forest is impacted by silviculture practices.
Clear cutting, especially up to stream banks, increase erosion and
runoff. In addition to the impacts of sedimentation for erosion,
there are impacts from scouring of the substrate resulting from
increased water velocity. This scouring causes the substrate to
shift and the mussels to be displaced. There is some evidence
that the Brown's Creek population is affected by domestic pollution
from upstream houses and farms. The Louisiana pearlshell is
threatened by its limited range and low numbers. Many of the streams
where this species occurs are isolated from each other. This creates
isolated gene pools that are vulnerable to loss of genetic
variability. Because this species depends upon water currents to
transport gametes from one individual to another, isolation and
reduced density of populations decreases the likelihood of successful
reproduction.
Collecting poses a significant threat to this species.
UNAPPROVED PLAN:
Recovery plan preparation will begin in late FY88
Service to work with the Forest Service in designing timber
harvest procedures that will not be detrimental to the species. The
U.S. Air Force will be informed of the specific location of the
species to ensure that habitat will remain undisturbed. Residents of
source areas for runoff will be advised of means to reduce or
eliminate impacts on nearby streams.
Management Practices - 2 (DRAFT) - References
Species PEARLSHELL, LOUISIANA
Species Id ESIS404026
Date 13 MAR 96
References
***** REFERENCES FOR ALL NARRATIVES EXCEPT N-OCCURRENCE *****
01 Louisiana Natural Heritage Program. 1985 Status of
Margaritifera hembeli (Unionacea:Margaritiferidae) in
Kisatchie National Forest, Evangeline Ranger District,
Rapids Parish, Louisiana. November 1986. An unpublished
report to the U.S. Forest Service, 20pp.
***** REFERENCES FOR N-OCCURRENCE NARRATIVE ONLY *****
01 Louisiana Natural Heritage Program. 1985. Status of
Marquaritifera hembli (Unionaceae:Margaritiferidae) in
Kisatchie National Forest, Evangeline Ranger District, Rapids
Parish, Louisiana, November 1985. An unpublished report to
the U.S. Forest Service, 20 pp.
References - 1