Asian Clam  (Corbicula fluminea)

DESCRIPTION

Adults can reach 50 mm in length. The shell is ovate and deep at the hinge. The exterior of the shell is normally a yellow-green to brown in color with thick, concentric rings. Dark shell morphs exist but are limited to the southwestern United States. The inside of the shell is layered with polished, light purple nacre. The light-colored shell morph has a yellow-green to light brown periostracum and white to light blue or light purple nacre while the darker shell morph has a dark olive green to black periostracum and a deep royal blue nacre They have three cardinal teeth in each valve with two lateral serrated teeth in each side of the right valve and only one in each side of the left valve. 

 

Exterior of left valve	Interior of right valve	View of right side of undissected clam. Right valve and mantle lobe removed.
Figure credit: Richard Fox ( rsfox@lander.edu ), Department of Biology, Lander University, Greenwood, SC 29649 Source from: Invertebrate Anatomy: Corbicula fluminea,  http://www.lander.edu/rsfox/corbicula.html

Life History: The sexes are normally separate, however, hermaphrodites exist and are capable of self-fertilization. The spawning season lasts about 6 months starting in early summer. Fertilization takes place in the inner gills. The first larval stage called a trochophore (15-20 microns) develops on the inner gill. The second stage called the veliger (- 0.2 mm) is incubated on the gill also. This is when the characteristic D-shaped shell begins. At approximately 1 mm, the juvenile is discharged and begins its adult life on the bottom. Pigments and growth rings should then be visible. They reach maturity at 6-10 mm with a life span of about 1-4 years. Their primary source of food is phytoplankton.

(Source from: 1. Asian Clam: Florida Caribbean Science Center & U.S. Geological Survey, http://www.fcsc.usgs.gov/corbicula3.pdf; 2. Asian Clam: USGS Nonindigenous Aquatic Species, http://nas.er.usgs.gov/mollusks/docs/co_flumi.html)

IMPACTS

The Asian Clam is a known biofouler in power plant and industrial water systems and has also caused problems in irrigation canals and pipes. Ecologically, this species can alter benthic substrates and complete with native mussel species for food and space. In addition, Asian clams appear to be capable of tolerating polluted environments better than many native bivalves

(Source from: 1. Asian Clam: Florida Caribbean Science Center & U.S. Geological Survey, http://www.fcsc.usgs.gov/corbicula3.pdf; 2. Asian Clam: USGS Nonindigenous Aquatic Species, http://nas.er.usgs.gov/mollusks/docs/co_flumi.html; 3. Asian Clam (Corbicula fluminea) in the Gulf of Mexico, http://www.gsmfc.org/nis/nis/Corbicula_fluminea.html)

(Source from: 1. Asian Clam: Florida Caribbean Science Center & U.S. Geological Survey, http://www.fcsc.usgs.gov/corbicula3.pdf)

The Asian clam is likely to spread in North America until it reaches its lower temperature tolerance. In closed environments, such as power plants, mechanical or chemical control methods can be employed to reduce or eliminate this species where problems occur. To eliminate the source of many introductions, navigation and dredging activities should be investigated.

Exotic species can be accidentally spread by boaters who travel from infested to uninfested waters. Some species (e.g., Zebra Mussel) can be picked-up and transported on boating equipment including boats, trailers, motors, tackle, downriggers, anchors, axles, rollers, and centerboards. As a boater, you help prevent this from happening. To avoid spreading exotic species, follow these easy steps before transporting your boat to another waterway.

BEFORE leaving the boat launch

INSPECT your boat, trailer and equipment and remove any plants and animals.
DRAIN, on land, all water from the motor, livewell, bilge, and transom well. Some exotics may not be visible to the naked eye.
EMPTY your bait bucket on land. Never release live bait into a waterway, or transfer aquatic animals between waterways. 

AFTER leaving the boat launch

WASH your boat, tackle, trailer, and  other equipment to kill any exotic species not visible at the boat launch. This can be done with 104°F tap water, or a high-pressure sprayer. or
DRY  your equipment for at least five days-some exotics can survive for long periods of time out of water.
LEARN what these organisms look like, and know which waterways are infested. 
REPORT any new infestations to any Sea Grant or your Department of Natural Resources.

Source: 1. Illinois-Indiana Sea Grant publication, IL-IN-SG-98-1, http://www.iisgcp.org/; 2. Asian Clam: Florida Caribbean Science Center & U.S. Geological Survey, http://www.fcsc.usgs.gov/corbicula3.pdf)

Asian Clam: USGS Nonindigenous Aquatic Species
    http://nas.er.usgs.gov/mollusks/docs/co_flumi.html
    This site discusses the identification, native range, means, and impact of introduction 

Asian Clam: Florida Caribbean Science Center & U.S. Geological Survey
    http://www.fcsc.usgs.gov/corbicula3.pdf
    This information bulletin includes the identification, native range, life history, habitat, occurrences, impacts, and control and management.

Asian Clam (Corbicula fluminea) in the Gulf of Mexico Region
    http://www.gsmfc.org/nis/nis/Corbicula_fluminea.html
    This site provides information regarding Asian clam including its features, biology, maximum size, distribution, current status of this species in the Gulf of Mexico Ecosystems, potential impacts, and references. 

Asian Clam: Illinois Natural History Survey Mollusk Collection
    http://www.inhs.uiuc.edu/cbd/musselmanual/page174_5.html
    This site introduces key characters, description, habitat, and status.

Invertebrate Anatomy: Corbicula fluminea: Department of Biology, Lander University
    http://www.lander.edu/rsfox/corbicula.html
    This page provides very detailed descriptions about this species (e.g., Shell, Soft Anatomy, Mantle and mantle cavity, etc.)

Asiatic Clam, Corbicula fluminea: Ecology Group, Pacific Northwest National Laboratory
    http://www.pnl.gov/ecology/Rivers/Aquarium/Clam.html
    This site shows life history of the Asian Clam, and explain how to raise and feed this clam in the classroom with figures.

Asian Clam: U.S. Army Engineer Research and Development Center (ERDC), Zebra Mussel Information System
    http://www.wes.army.mil/el/zebra/zmis/zmishelp4/corbicula_fluminea_the_asian_clam_larva.htm 
    This page includes very detailed species description with good figures.

Invasion of Corbicula Fluminea, the Asiatic Clam, into the Norfolk Broads: Aquatic Ecology Group, Cambridge University
    http://www.zoo.cam.ac.uk/zoostaff/aldridge/corbicula.html
    This site introduces Stephan Mueller's field trip story related to the Asiatic clam.