Corbicula fluminea is a species of freshwater clam native to eastern Asia which has become a successful invasive species throughout North America, South America, and Europe. Corbicula fluminea is commonly known in the west as the Asian clam or Asiatic clam. In Southeast Asia, C. fluminea is known as the golden clam, prosperity clam, pygmy clam, or good luck clam.
Corbicula have had global success as an aquatic invasive species, having been introduced to a novel range including South America, North America and Europe. Human industrial activity, such as transport of larvae via ballast water in container ships, has been noted in the literature as a chief invasion vector. A market exists for Asian clams for human consumption in Japan, China, and other countries in the region. According to the United States Geological Survey, C. fluminea is likely to continue to expand its North American range until it reaches the maximum extent of its low temperature tolerance. The periostracum of the shell is normally yellow-green, with concentric growth rings of the prismatic layer visible through the proteinous outer layer. The periostracum can flake, allowing the white prismatic layer to show through. The shells exhibit a light purple nacre on the inside.
Studies on which abiotic habitat characteristics are most strongly associated with Asian clam population abundance have produced varying results. Brazilian habitats have been found to have support the largest abundances of invasive Corbicula spp. in areas with coarser dominant sediment fractions, while negatively correlated with increasing levels of organic matter. Others studies have shown abiotic habitat characteristics such as water redox potential, inorganic nutrient content, hardness, and organic matter content in tandem with the amount of very coarse sand combine to explain 59.3% of Corbicula population habitat association via statistical tests. Asian clam invasions seem to be limited by elevation (88% of the invaded range is below 500m elevation), latitude (90% lies between latitudes 30°and 55°) as well as the minimum winter temperature (-10°C) of the ecosystem.
Corbicula fluminea enjoys several physiological capabilities which are advantageous in promoting its invasion of novel lentic/lotic environments including:
Corbicula fluminea is a self-fertilizing, simultaneous hermaphrodite which can asexually produce internally-brooded, semi-buoyant planktonic larvae when spermiogenesis is induced at temperatures above 10°C. This allows C. fluminea to colonize novel habitats at an advanced rate.
Corbicula fluminea is an active suspension feeder, and in the process of feeding by pumping water through its body (as well as feeding on interstitial sedimentary material via pedal feeding when suspended grazing items are limited). They feed primarily on phytoplankton (algae), which they actively filter out the water, but may pedal feed on organic matter in the sandy or muddy bottoms of streams, lakes, or canals where the clam establishes a population.
Right after reaching maturity, these clams produce eggs, followed by sperm. Throughout adult life, Corbicula is a self-fertile simultaneous hermaphrodite which can broadcast spawn up to 570 mucoid larvae per day per individual, and more than 68,000 per year per individual. Larvae are ~200 microns in length when discharged from an adult and dispersed through water until becoming sessile adults. Adults can reach a length of about 5 cm.
