Tellina flumineaO. F. Müller, 1774 (original combination)
Corbicula fluminea is aspecies offreshwaterclam native to eastern Asia which has become a successful invasive species throughout the world, including North America, South America, Europe,[1] and New Zealand.[2][3] It is native to freshwater environments of Eastern Asia, includingRussia,Thailand, thePhilippines,China,Taiwan,Korea, andJapan.C. fluminea also occurs naturally in freshwater environments ofAfrica.[4]Corbicula fluminea is commonly known in the west as theAsian clam,Asiatic clam, orAsian gold clam. In Southeast Asia,C. fluminea is known as thegolden clam,prosperity clam,pygmy clam, orgood luck clam. In New Zealand, it is commonly referred as thefreshwater gold clam.[2][3]
Corbicula have had global success as anaquatic invasive species, having been introduced to a novel range includingSouth America,[5]North America andEurope. 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.[6] A market exists for Asian clams for human consumption in Japan, China, and other countries in the region.[6] According to theUnited 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.[7] Theperiostracum of the shell is normally yellow-green, brown, or black with concentric growth rings of theprismatic layer visible through the proteinous outer layer. The periostracum can flake, allowing the white prismatic layer to show through. The shells exhibit a light purplenacre on the inside.
As afilter feeder,[2][8][9]Corbicula strains suspended contents of nearby water and absorbing material to feed itself. Large quantities of toxins are absorbed in their gut,[10] accumulating high concentrations of toxins.[11] The clams excrete large quantities of inorganic chemicals, such as nitrogen and phosphorus, after feeding off sediment.[12] Despite edibility ofCorbicula in native countries,Coribicula sourced from New Zealand'sWaikato River is considered not safe to eat,[13] as caused by pollution in the river.[10][14]
Corbicula is a successful breeder in the rivers and lakes of many countries in the world, breeding densely in localized water,[12][15] and transported elsewhere via water currents or by the movement of humans and their waterborne apparatus.[12] This allows them to outcompete against native invertebrates,[16] including mollusks such as mussels,[17] for phytoplankton as food.[17]Corbicula has shown to interfere with water-based infrastructure created by humans,[18][11][10] such as water treatment and hydroelectric dams,[12][11] by clogging them up.[2]
Right after reaching maturity, these clams produce eggs, followed by sperm. Throughout adult life,Corbicula is a self-fertile simultaneoushermaphrodite which can broadcast spawn up to 570mucoid larvae per day per individual, and more than 68,000 per year per individual.[19] Larvae are ~200 microns in length when discharged from an adult and dispersed through water until becomingsessile adults.[19] Adults can reach a length of about 5 centimetres (2.0 in).[citation needed]
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).[20] They feed primarily onphytoplankton (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.[1]
Corbicula fluminea is aspecies offreshwaterclam, anaquaticbivalvemollusk in the familyCyrenidae.[21]C. fluminea is often confused withCorbicula fluminalis due to the two species' similar color and texture. Two species may be present in some introduced populations:C. fluminea andC. fluminalis.[22] The names themselves are sometimes confused in the literature (e.g. by being called"Corbicula fluminata").
The ratio of width and height inC. fluminea is on average 1.1. InC. fluminalis it is smaller (0.97); still, there is much variation and considerable overlap in shape. Most easily, they can be distinguished by the number of ribs on the shell;C. fluminea has 7 to 14 ribs per cm,C. fluminalis 13 to 28.[23] This character is already clearly recognizable (albeit only by direct comparison) in very small (5 mm diameter) specimens. In addition, when viewed from the ventral side (looking at the opening between the shells),C. fluminalis is rounder, almost heart-shaped, whileC. fluminea has a slightly flatter shape like a teardrop with a notched broad end. Small specimens ofC. fluminalis are almost spherical, while those ofC. fluminea are decidedly flattened. All these differences except the rib number are a consequence ofC. fluminalis having a markedly more swollen, pointed and protrudingumbo.
Many coastal rivers with a heavy industrial shipping presence in the invaded range ofC. fluminea sustain Asian clam populations.[6] Various non-indigenous populations ofC. fluminea include:
Between August 15–28, 2020 inBriggs Lake inMinnesota;[45] howeverUMN Extension does not believe they are able to naturally survive in Minnesota, instead surviving only in the higher temperatures ofpower plant coolant water[45]
Found in thePend d'Oreille River in British Columbia, a tributary of the Columbia, in the spring of 2021[49]
First discovered in theWaikato River in the Waikato Region of New Zealand, in May 2023.[2] Ministry of Primary Industries along with the Waikato Regional Council had found the species at Bob's Landing,Lake Karapiro - upriver from Hamilton, New Zealand's fourth most populous city.[3][2] The clams have successfully colonized throughout a portion of the Waikato River.[13] As a precaution against further spread of the clams, numerous lakes and rivers were closed off,[50][51] and many other regions have installed mandatory QR codes[52] and permanent washing stations.[53]
Human activities are the chief reason for the wide dispersal ofC. fluminea as an invasive aquatic organism.[6] Its global invasion probably started with Asian immigration in North America during the 1920s, as it was used as food source by these communities.[6]Corbicula fluminea, along with other exotic bivalve larvae, may be accidentally transported via ballast water or recreational boaters.[6][54] Furthermore, the species is common in the aquarium trade and can be intentionally or unintentionally released in the wild by aquarists.[6]
Corbicula fluminea enjoys several physiological capabilities which are advantageous in promoting its invasion of novellentic/lotic environments including:
Ability to broadcast gametes over a broad area by utilizing water flow (in rivers)
Tolerance of a wide variety of substrate/habitat types,[55]
Corbicula fluminea is a self-fertilizing, simultaneous hermaphrodite which can asexually produce internally-brooded, semi-buoyant planktonic larvae whenspermiogenesis is induced at temperatures above 10 °C (50 °F).[19] This allowsC. fluminea to colonize novel habitats at an advanced rate.[55]
Studies on which abiotic habitat characteristics are most strongly associated with Asian clam populationabundance have produced varying results. Brazilian habitats have been found to have support the largest abundances of invasiveCorbicula spp. in areas with coarser dominant sediment fractions, while negatively correlated with increasing levels of organic matter.[56] 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% ofCorbicula population habitat association via statistical tests.[44] Asian clam invasions seem to be limited by elevation (88% of the invaded range is below 500m elevation[1]), latitude (90% lies between latitudes 30°and 55°[1]) as well as the minimum winter temperature (−10 °C (14 °F)) of the ecosystem.[1]
Corbicula fluminea reworks the sediments it resides on through the process ofbioturbation.[20] Asian clams are considered biodiffusors similar to marine clam species due to their observed bioturbation activity which may negatively affect other members of thebenthic community in invaded areas.[20] Excessive excretion of inorganic chemicals such as nitrogen and phosphorus imbalance concentrations of oxygen in the water, encouraging the growth of algae and cyanobacteria, as a byproduct of the excretion of these clams.[12]
Corbicula has also been shown to profoundly influence community dynamics within themacrobenthos of invaded systems.[57]Corbicula has been shown to remove as much as 70% of phytoplankton biomass in reaches of invaded rivers with a robust clam population.[58] The clam has also been reported as causing a decline of dissolved oxygen in the water of the same river system with wide-ranging second-order effects.[58]
The primary economic and social impact of the invasion ofC. fluminea has been billions of dollars in costs associated with clogged plumbing and, heat exchangers, or other human-created infrastructure.[59] Ecologically,C. fluminea contributes to declines and replacement of highly vulnerable, already threatened native clams.[60]
The first recorded instance ofCorbicula presence in the scientific literature in the Western Hemisphere was of its introduction into British Columbia circa 1924, followed by a spread throughout the Pacific Northwest and across the American south through South America. Invasions in Europe and Central America were more recent, first appearing in Caribbean countries in 1998.[1]
Corbicula was discovered in New Zealand along a stretch of the Waikato River in May 2023.[61][2] According to the Ministry of Primary Industries, the clams have likely populated in the river for several years prior to discovery.[2] Based on patterns of unsuccessful eradication ofCorbicula overseas, eradication ofCorbicula is predicted to be near-impossible in New Zealand.[62][63]
They have been blamed for algal blooms and concerns exist they will outcompete and displace native species such as the montane pea clam (Pisidium spp.) and the ramshorn snail (Planorbidae). Efforts are underway atLake Tahoe to smother the clams on the bottom with rubber mats.[64] In August 2020 routine inspections inWyoming found several watercraft to be heavily infested including one withC. fluminea.[65][66] On October 16, 2020, theMontana Department of Fish, Wildlife and Parks recommended thatLake Elmo — inBillings — be drained to dry out and freeze to death theC. fluminea there.[67][68][69]
^abUSGS (2001): Nonindigenous species information bulletin: Asian clam,Corbicula fluminea (Müller, 1774) (Mollusca: Corbiculidae).PDF fulltext
^Ituarte, C., 1981. Primera noticia acerca de la introducción de pelecípodos asiáticos en el área rioplatense (Mollusca: Corbiculidae). Neotropica 27 (77): 78-83
^abcMcMahon, R.F. (1999) Invasive Characteristics of the Freshwater BivalveCorbicula fluminea. In R. Claudi & J.H. Leach (Eds.),Nonindigenous Freshwater Organisms: Vectors, Biology, and Impacts (pp. 315-343).
^Elliott, Paul; Zu Ermgassen, Philine S.E. (2008). "The Asian clam (Corbicula fluminea) in the River Thames, London, England".Aquatic Invasions.3 (1):54–60.doi:10.3391/ai.2008.3.1.9.
^abDarrigran, G.; Damborenea, C. "La almeja de agua dulceCorbicula fluminea (Müller, 1774)". In Penchaszadeh, P.E (ed.).Invasores. Invertebrados exóticos en el Río de La Plata y región marina aledaña. Buenos Aires: Eudeba. pp. 133–177.
^Archuby, F.; Macchi, P.; Darrigran, G. (2013). "Corbicula fluminea (Muller 1774) (Corbiculidae) en el Alto Valle del Río Negro".I Congreso Argentino de Malacología. La Plata: UNLP.
^Martítnez E, Rafael (1987). "Corbicula manilensis molusco introducido en Venezuela".Acta Científica Venezolana.38:384–385.
^Ojasti, Juhani.; González Jiménez, Eduardo; Szeplaki Otahola, Eduardo; García Román, Luis B. (2001).Informe sobre las especies exótica en Venezuela. Caracas: Ministerio del Ambiente y de los Recursos Naturales.ISBN980-04-1254-9.
^Lasso, Carlos A.; Martínez Escarbassiere, Rafael; Capelo, Juan Carlos.; Morales Betancourt, Mónica; Sánchez- Maya, Alejandro (2009). "Lista de los moluscos (Gastropodos_Bivalvia) dulceacuícolas y estuarinos de la cuenca del Orinoco (Venezuela)".Biota Colombiana.10 (1–2):63–74.
^Jueg, U. & Zettler, M.L. (2004): Die Molluskenfauna der Elbe in Mecklenburg-Vorpommern mit Erstnachweis der Grobgerippten KörbchenmuschelCorbicula fluminea (O. F. Müller 1756).Mitteilungen der NGM4(1): 85-89. [in German]PDF fulltextArchived 2007-09-27 at theWayback Machine
^Hayden, B. and Caffrey, J.M. 2013. First recording of the Asian Clam (Corbicula fluminea (Müller, 1774)) from the River Shannon, with preliminary notes on population size and class distribution.Ir. Nat. J.32: 29 - 31.
^Beran L. (2000) "First record ofCorbicula fluminea (Mollusca: Bivalvia) in the Czech Republic".Acta Societatis Zoologicae Bohemicae64: 1-2.
^ab(in Czech) Horsák M., Juřičková L., Beran L., Čejka T. & Dvořák L. (2010). "Komentovaný seznam měkkýšů zjištěných ve volné přírodě České a Slovenské republiky. [Annotated list of mollusc species recorded outdoors in the Czech and Slovak Republics]".Malacologica Bohemoslovaca, Suppl. 1: 1-37.PDF.
^Beran L. (2006). Spreading expansion ofCorbicula fluminea (Mollusca: Bivalvia) in the Czech Republic. – Heldia 6 5/6: 187-192.
^Pimentel, D., Zuniga, R. & Morrison, D. (2005) Update on the environmental and economic costs associated with alien-invasive species in the United States.Ecological economics 52: 273-288.
Weitere, M. et al. (2009) Linking environmental warming to the fitness of the invasive clam Corbicula fluminea, Global Change Biology, Volume 15 Issue 12, Pages 2838 - 2851[1]
