CAROLINA HEELSPLITTER

Lasmigona decorata

FAMILY:	Unionidae

STATUS:	Endangered, Federal Register, June 30, 1993

DESCRIPTION:	The Carolina heelsplitter was originally described as 
Unio decoratus by Lea
(1852). In 1970, this species was synonymized with Lasmigona 
subviridis (Conrad 1835) by Johnson
(1970). Clarke (1985) recognized the Carolina heelsplitter as a 
distinct species, Lasmigona decorata,
and synonymized Unlo charlottensis (Lea 1863) and Unio insolidus 
(Lea 1872) with Lasmigona
decorata.

The Carolina heelsplitter has an ovate, trapezoid-shaped, 
unsculptured shell. The shell of the largest
known specimen of the species measures 114.8 millimeters (mm [4.6 
inches]) in length, 39.0 mm
(1.56 inches) in width, and 68.0 mm (2.7 inches) in height 
(Keferl 1991). The shell's outer surface
varies from greenish brown to dark brown in color, and shells 
from younger specimens have faint
greenish brown or black rays. The nacre (inside surface) is often 
pearly white to bluish white, grading
to orange in the area of the umbo (Keferl 1991). However, in 
older specimens the entire nacre may
be a mottled pale orange (Keferl 1991).

RANGE: The Carolina heelsplitter currently has a very fragmented, 
relict distribution but historically
was known from several locations within the Catawba and Pee Dee 
River systems in North Carolina
and the Pee Dee and Savannah River systems, and possibly the 
Saluda River system, in South
Carolina. Historically, the species was collected from the 
Catawba River, Mecklenburg County,
North Carolina; several streams and "ponds" in the Catawba River 
system around the Charlotte area
of Mecklenburg County, North Carolina; one small stream in the 
Pee Dee River system in Cabarrus
County, North Carolina; one "pond" in the Pee Dee River system in 
Union County, North Carolina;
and an area in South Carolina referred to only as the "Abbeville 
District," a terminology no longer
employed (Clarke 1985, Keferl and Shelly 1988, Keferl 1991). The 
records from the Abbeville
District, South Carolina, were previously believed to have been 
from the Saluda River system (Clarke
1985, Keferl and Shelly 1988, Keferl 1991). However, as a result 
of surveys funded by the
U.S. Forest Service and South Carolina, a population of the 
Carolina heelsplitter was discovered in
the spring of 1995 in the Savannah River system (Stevens Creek 
watershed) (Alderman 1995).
Therefore, the historic records from the Abbeville District may 
have been from either the Saluda
River system or the Savannah River system or both.

Recent collection records (Keferl and Shelly 1988, Keferl 1991, 
Alderman 1995) indicate that the
Carolina heelsplitter has been eliminated from all but one of the 
streams from which it was known to
have been originally collected. Only four populations of the 
species are presently known to exist.
One small remnant population occurs in the Catawba River system 
in Waxhaw Creek, a tributary to
the Catawba River, in Union County, North Carolina; another small 
population occurs in a short
stretch of Goose Creek, a tributary to the Rocky River in the Pee 
Dee River system, in Union County,
North Carolina; a third, slightly larger population, survives in 
the Lynches River, part of the Pee Dee
River system, in Chesterfield, Lancaster, and Kershaw Counties, 
South Carolina, and extends into
Flat Creek, a tributary to the Lynches River in Lancaster County, 
South Carolina. In the Savannah
River system the species is known only from Turkey Creek and two 
of its tributaries, Mountain Creek
and Beaverdam Creek, in Edgefleld County, South Carolina. No 
evidence of a surviving population
has been found in recent years in the Saluda River system (Keferl 
1991).

The species has been reduced to a few short reaches of each of 
these streams, primarily as a result
of impoundments and channelization projects and the general 
deterioration of water quality resulting
from siltation and other pollutants contributed as a result of 
poor land use practices.

HABiTAT:	Historically, the species was reported from small to 
large streams and rivers as well as
ponds. The "ponds" referred to in historic records are believed 
to have been mill ponds on some of
the smaller streams within the species' historic range (Keferl 
1991). Presently, the species is known
to occur in only six small streams and one small river and is 
usually found in mud, muddy sand, or
muddy gravel substrates along stable, well-shaded stream banks 
(Keferl and Shelly 1988, Keferl
1991). However, in Mountain Creek in Edgefleld County, South 
Carolina, two live individuals were
found near the center of the stream channel in a relatively 
silt-free substrate comprised primarily of
a mixture of sand, gravel, and cobble (personal observation, 
1995). It is conceivable that this is the
preferred habitat type for the species and that in other areas 
degradation of the gravelly substrates has
restricted the species to less suitable habitats. The stability 
of stream banks appears to be very
important to the species (Keferl 1991).

Like other freshwater mussels, the Carolina heelsplitter feeds by 
filtering food particles from the water
column. The specific food habits of the species are unknown, but 
other freshwater mussels have been
documented to feed on detritus, diatoms, phytoplankton, and 
zooplankton. The reproductive cycle
of the Carolina heelsplitter is likely similar to that of other 
native freshwater mussels. Males release
sperm into the water column; the sperm are then taken in by the 
females through their siphons during
feeding and respiration. The females retain the fertilized eggs 
in their gills until the larvae (glochidia)
fully develop. The mussel glochidia are released into the water, 
and within a few days they must
attach to the appropriate species of fish, which are then 
parasitized for a short time while the
glochidia develop into juvenile mussels. They then detach from 
their "fish host" and sink to the
stream bottom where they continue to develop, provided they land 
in a suitable substrate with the
correct water conditions. The Carolina heelsplitter' s life span, 
the fish host species, and many other
aspects of its life history are unknown.

REASONS FOR CURRENT STATUS: The decline in the species throughout 
its range has been
attributed to several factors, including siltation resulting from 
poorly implemented agricultural,
forestry, and development activities; golf course construction; 
road construction and maintenance;
runoff and discharge of municipal, industrial, and agricultural 
pollutants; habitat alterations associated
with impoundments, channelization, dredging, and sand mining 
operations; and other natural and
human-related factors that adversely modify the aquatic 
environment. Many of these same factors
threaten the remaining populations of the species.
Waxhaw Creek and Goose Creek are small streams containing a 
limited amount of suitable habitat
for the Carolina heelsplitter. The two populations within Waxhaw 
and Goose Creeks appear to be
extremely small and declining, and restricted to a few scattered 
sites within short reaches of each of
these creeks. The Lynches River/Flat Creek population also 
appears to be relatively small and is
restricted to a few scattered sites along short reaches of these 
streams (Keferi, personal
communication, 1991). The Turkey Creek/Mountain Creek/Beaverdam 
Creek population was only
recently discovered (Alderman 1995), and little is presently 
known about the status and abundance
of the species in these three streams. The low numbers of 
individuals and the restricted range of each
of the surviving populations makes them extremely vulnerable to 
extirpation from a single
catastrophic event or activity, such as a toxic chemical spill, 
temporary failure of a waste treatment
facility, channel alteration, etc. Also, the existing and 
potential future land uses of the surrounding
area threaten the habitat and water quality of all four 
populations with increased discharge or runoff
of silt, sediments, and organic and chemical pollutants.

MANAGEMENT AND PROTECTION: Assuring the long-term survival of the 
Carolina
heelsplitter will require, at a minimum: (1) protecting the 
existing water and habitat quality of the
streams where the Carolina heelsplitter is still surviving; and, 
(2) improving degraded portions of the
species habitat and, reestablishing and protecting additional 
populations of the species within portions
of its historic range from which it has extirpated. This will 
require compliance with existing State and
Federal regulations and assistance from the public and local 
governments and industries in
implementing recovery actions. Also, additional research on the 
threats to the species, the
environmental requirements of the heelsplitter and fish host(s), 
and propagation and reintroduction
techniques for freshwater mussels is needed.

REFERENCES

Alderman, J. M. 1995. Freshwater mussel inventory of the Stevens 
Creek Subbasin, Long Creek
Ranger District, Sumter National Forest, South Carolina. 
Unpublished report to the
U.S. Forest Service. 38 pp.

Clarke,	A. H. 1985. The Tribe Alasmidontini (Unionidae: 
Anodontinae), Part II: Lasmigona and
Simpsonaias. Smithsonian Contributions to Zoology, (399): 57-60. 
Smithsonian Institution
Press, 75 pp., 22 figures, 14 tables.

Conrad, T. A. 1835. Appendix (to: New Fresh Water Shells of the 
United States with colored
illustrations, and a monograph of the genus Anculotus of Say; 
also a synopsis of the American
naiades. 76 pp.) Additions to, and corrections of, the catalogue 
of species of American
naiades, with descriptions of new species and varieties of fresh 
water shells. Judah Dobson,
Philadelphia, PA. P. 4, p1. 9, fig. 1.

Keferl,	E. P. 1991. A Status Survey for the Carolina heelsplitter 
(Lasmigona decorata), a
Freshwater Mussel Endemic to the Carolinas. Unpublished report to 
the U.S Department
of the Interior, Fish and Wildlife Service. 51 pp
Keferl,	E. P., and R. M. Shelly. 1988. The Final Report on a 
Status Survey of the Carolina
Heelsplitter, Lasmigona decorata, and the Carolina elktoe, 
Alasmidonta robusta.
Unpublished report to the U.S. Department of the Interior, Fish 
and Wildlife Service. 47 pp.

Lea, I.	1852. Description of New Species of the family Unionidae. 
Transactions of the American
Philosophical Society, 10:253-294. (Reprinted in 1852 in 
Observations on the Genus Unio,
5:9-50.)

 .	1863. Description of twenty-four New Species of Unionidae of 
the United States.
Proceeding of the Academy of Natural Sciences of Philadelphia, 
15:191-194.

 .	1872. Description of twenty-nine New Species of Unionidae of 
the United States.
Proceeding of the Academy of Natural Sciences of Philadelphia, 
24:155-161.


AUTHOR:	John A. Fridell (see address below)

For more information please contact:

Mr. John A. Fridell
U.S. Fish and Wildlife Service
160 Zillicoa Str.
Asheville, North Carolina 28801
Telephone:	(704) 258-3939 ext. 225

Mr John M. Alderman
North Carolina Wildlife Resources Commission
244 Red Gate Road
Pittsboro, North Carolina 27321
Telephone:	(919) 542 5331

Dr. Eugene Keferl
Department of Natural Science
Brunswick Junior College
Brunswick, Georgia 31523
Telephone:	(912) 264 7233