Corbicula an annotated bibliography 1774 2005

The cholinesterase activity is used since several years as marker of carbamates and organophosphorous in human contamination. This permitted to envisage the use of molluscs ChE activity to monitor aquatic contamination. In this way, our work was to perform this biomarker in the following aquatic bivalves: the marine mussel (Mytilus edulis) for and the freschwater bivalve Corbicula fluminea. In a first time, we have purified and characterized the cholinesterases from the two molluscs. We have also determined the in vivo IC 50 for two pesticides (carbaryl and methylparathion). In a second time, two in situ experiments, in Baltic sea and on the Adour-Garonne basin, showed smaller activity in the most polluted sites than in the reference sites.

Moraal, J. M. 1961. Een fossiele zoetwaterschelp van de Zeeuwse Starnden. Publicaties van Nederlandse Geologische Vereniging, NS 9:250 253.

Corbicula fluminalis is collected as a fossil on the beaches of Zeeland, the Netherlands.

Mörch, O. A. L. 1861. Description d'une nouvelle espece du Corbicula. Journal de Conchyliologie 9:347 348.

Mörch, O. A. L. 1872. Catalogue des mollusques terrestres et fluviatiles des anciennes colonies danoises du golfe du Bengale. Journal de Conchyliologie 20:303 345.

Morelet, A. 1862. Diagnoses testarum Indo sinarum   Series Prima. Revue et Magazin du Zoologie (2) 14:477 481.

Morelet, A. 1865. Addition `a la faune malacologique de l'Indochine. Journal de Conchyliologie 13:225 228.

Morelet, A. 1868. Mollusques terrestres et fluviatiles. IN: Voyage du Dr. Friederich Welwitsch ex'ecut'e par ordre governement Portugais dans les Royaumes d'Angola et de Benguella (Afrique Equinoxiale). (Paris). 102 pp.

Morelet, A. 1875. Series Conchyliologiques: Indo Chine. pp. 227 377.

Morgan, D. E., M. Keser and J. F. Foertch. 1995. Population dynamics of the Asiatic clam, Corbicula fluminea, at three electrical power facilities in the Lower Connecticut River. Northeast Conference on Non-indigenous Aquatic Nuisance Species, Cromwell, Connecticut, 25 January. Connecticut Sea Grant CT-SG-95-04.

Since May 1990, when Asiatic clams (Corbicula fluminea) were first removed from the service water system of the Connecticut Yankee electric generating station, this exotic species has been monitored at three electrical power facilities: Connecticut Yankee (CY), Middletown Station (MS), and South Meadow Station (SM). The Asiatic clam continues to persist in the lower Connecticut River in spite of harsh winter conditions, which have killed up to 99% of the population each year. The patterns in summer fecundity and growth of clams have remained similar from 1991 through 1994, even though densities have fluctuated enormously. Population densities peaked in 1992, when clams exceeded 25,000/m² at MS, but have remained below 1,000/ m² in 1993 and 1994. Spawning and the release of juveniles occurs nearly continuously from June to September, may occur twice a year for some larger clams, and peaks during the warmest (25-30^oC) month, August. Growth and reproduction appear to require water temperatures above 16-18^oC. Growth is size dependent, with peak growth rates of >1 mm/wk for small adult clams (9-10 mm). Growth slows to less than 2 mm per growing season (May to November) for clams larger than 36 mm. High winter mortalities appear to be limiting this population, but thermal discharges, springs, and deep waters appear to be refuges during harsh winters. The potential for periodic population explosions will continue to threaten industrial raw water systems because low winter mortalities followed by high summer growth and reproduction, as noted, could quickly return river populations to concern levels.

Morgan, D. E., M. Keser, J. T. Swenarton and J. F. Foertch. 2004. Effect of Connecticut Yankee Power Plant on population dynamics of Asiatic Clams and their interactions with native bivalves. American Fisheries Society Monograph No. 9:419-439.

The Asiatic clam (also known as Asian clam) Corbicula fluminea, first reported in the Connecticut River in 1990, was the dominant bivalve around Connecticut Yankee nuclear power station (CY) during the 10-year period (1991-2000) of this study. This population extended its range upriver at least 22 km from 1991 to 1992. Corbicula winter survival was positively correlated with winter water temperatures and negatively correlated with spring freshet river flows. For example, no Corbicula were found following the two coldest winters of the study (1993-1994 and 1995-1996). Regardless of the level observed for winter population survival, study sites were repopulated each year by August, attributed to passive downstream movement from populations in refugia from winter stresses (e.g., upstream thermal discharges at Middletown and South Meadow power stations, or groundwater seeps). Small clams (2-mm size-class) dominated the CY thermal discharge canal during power plant operation because, by June of each year, discharge temperatures (>35^oC) exceeded the upper thermal tolerance for this clam. The CY discharge, therefore, was not an important winter refuge. In years following CY closure (1997-2000), a year-round Corbicula population was established in the discharge canal, but abundance at river sites around CY remained similar to levels observed during power plant operation. Our findings suggest that Corbicula has established a permanent population in the Connecticut River with little impact on native bivalves up to the last year of this study in 2000.

Morgan, D. E., M. Keser, J. T. Swenarton and J. F. Foertch. 2003. Population dynamics of the Asiatic clam, Corbicula fluminea (Müller) in the Lower Connecticut River: Establishing a foothold in New England. Journal of Shellfish Research 22(1):193-203.

The founding population of Corbicula fluminea in the Lower Connecticut River, discovered in 1990, was studied for ten years (1991-2000). Seasonal abundance of six size classes was monitored near three electric power plants. Corbicula abundance varied seasonally as well as annually, but peaked in 1992. Winter survival of clams was positively correlated with the average winter water temperature and negatively correlated with frequency of daily mean water temperatures less than or equal to 1^oC and with frequency of daily mean April spring freshet flows greater than or equal to 1700 m³/s. Higher winter survival at Middletown Station sites during most years, when compared with survival near Connecticut Yankee, was attributed to the influence of the Middletown Station thermal discharge. Thermal discharge did not support a permanent population at Connecticut Yankee because of temperature extremes during power plant operation in summer. Clam growth under ambient river temperatures began in May when water temperatures exceeded 10 ^oC and ceased in December when temperatures fell below this threshold. Cooling water discharges altered this seasonal growth pattern; growth began in November, as temperatures fell below 35 ^oC, and ceased in the summer, when discharge temperatures exceeded this upper thermal threshold. Reproduction occurred in the river when water temperatures were between 17 ^oC and 28 ^oC, typically from June to October. Peak spawning occurred in August. Discharge temperatures shifted clam reproduction back to spring (March to May). The key to Corbicula's success in establishing a population in the Connecticut River is its ability to colonize refugia from winter temperature and spring freshet flow extremes that often cause high clam mortality.

Morgester, J. J. 1967. Water quality and biologic conditions, South Bay Aqueduct, 1962 1966. California Department of Water Resources Report (Sacramento). xvi + 180 pp.

Mori, M., H. Matsushima, K. Tanaka, K. Murakami, K. Taki and N. Hayashi. 2003. Filtering and respiratory properties of a bivalve of Mashijimi (fresh water Corbicula leana) in Lake Tega. Global Threats to Large Lakes: Managing in an Environment of Instability and Unpredictability. International Association for Great Lakes Research (Ann Arbor, Michigan). p. 143.

Lake Tega with a water area of about 650 ha and an average water depth of 0.86 m, a natural freshwater lake located at 25 km northeast from Tokyo, has been known as the most eutrophicated lake in Japan. As eutrophication goes on, various peculiar species of living organisms decrease in number or become extinct, an example of which is a bivalve of "Mashijimi" in Japanese (fresh water Corbicula leana) and was once a typical peculiar species at Lake Tega. Although Mashijimis are inhabiting not in the lake but still in several inflowing rivers in the Lake Tega basin area, they have an excellent filtering function to remove the presence of water-blooms in the lake water. With a concept that Mashijimi is to revive at Lake Tega to apply its effective filtering function for improving the hyper-eutrophicated water quality of Lake Tega, batch experiments with open and closed systems were conducted to evaluate Mashijimi's filtering property. Accordingly, in a closed system under dark condition to control photosynthesis reaction it was estimated to range in between 0.25 and 1.3 liters/g-bivalve/day, which was clearly affected by the initial loading intensity of turbidity due to algae. Furthermore, Mashijimi's specific oxygen uptake rate was also shown similarly to be proportional to the initial loading intensity of turbidity.

Mori, S. 1971. Fourth report of the regular limnological survey of Lake Biwa 1970. Part 2. Benthos. Memoirs of the Faculty of Science, Kyoto University, Series Biology 5:16 34.

Mori, S. 1976. Sixth report of the regular limnological survey of Lake Biwa (1972). II. Benthos. Memoirs of the College of Science, Kyoto University, Series B, Biology 7(1):31 46.

The occurrence, density, and biomass of Corbicula sandai in Lake Biwa during 1972 is described.

Mori, S. 1978. Seventh report of the regular limnological survey of Lake Biwali (1973). III. Benthos. Memoirs of the Faculty of Science, Kyoto University, Series B, Biology 7(2):11 30.

It is noted that the pelecypod species Corbicula sandai reported in earlier works of the limnological survey were misidentifications of Corbicula leana. Benthic communities were observed in Lake Biwa, Japan, to study changes in biomass from 1966 1975. Oligochaeta showed an increasing trend had stopped or even decreased. The molluscs Sinotaia histrica of polluted areas were widely distributed; Semisulcospira decipiens had decreased; Corbicula sandai was decreasing and being replaced by Corbicula leana; and Sphaerium japonicum biwaense decreased. Larvae of Chironomus plumosus had increased conspicuously. A trend in eutrophication was seen in some degree in the change of Corbiculacea species, but there were signs of suspension of eutrophication as in decreases of oligochaetes and Sphaerium.

Moring, J. B. and D. R. Rose. 1997. Occurrence and concentrations of polycyclic aromatic hydrocarbons in semipermeable membrane devices and clams in three urban streams of the Dallas-Fort Worth Metropolitan Area, Texas. Chemosphere 34(3):551-566

Semipermeable membrane devices (SPMDs) and Asiatic clams, Corbicula fluminea (Müller), were deployed at stream sites in the Dallas-Fort Worth Metropolitan Area to assess the presence of bioavailable, dissolved polycyclic aromatic hydrocarbons (PAHs). Twenty-four PAHs were detected in SPMDs, 20 of which occurred at all sites. Only three PAHs were detected in the co-deployed clams. Throughout all sites, non-alkylated PAHs were found at greater levels in SPMDs than alkylated forms. Nine of 16 Priority Pollutant PAHs were detected in SPMDs. Estimated concentrations of PAHs in water were generally two to three orders of magnitude less than standard minimum analytical reporting levels; however, for benz (a) anthracene, benzo (a) pyrene, and chrysene, estimated concentrations in water exceeded the U.S. Environmental Protection Agency's human health criteria for these carcinogens in water and aquatic organisms.

Morlet, L. 1886. Diagnoses de Mollusques Terrestres et Fluviatiles du Tonkin.

Corbicula tonkiniana sp. nov. is described (p. 6) from Loc nam and Chu, Tonkin (Vietnam). Corbicula baudoni sp. nov. is described (p. 6) from Tonkin (Vietnam).

Morlet, L. 1886. Liste des coquilles recueillies, au Tonkin, par M. Jourdy, Chef d'Escadron d'Artillierie, et description d'especes nouvelles. Journal de Conchyliologie 34:257 295.

Morlet, L. 1889. Catalogue des coquelles recueilles par M. Pavie, dans le Cambodge et le Royaume de Siam, et description d'especes nouvelles. Journal de Conchyliologie 37:121 199.

Morlet, L. 1891. Contributions `a la faune malacologique de l'Indo Chine. Journal de Conchyliologie 39:230 254.

Morris, J. S. and R. W. Taylor. 1978. A survey of the freshwater mussels (Bivalvia: Unionidae) of the Kanawha River of West Virginia. The Nautilus 92(4):153 155.

During the summer of 1976 a survey of the upper Kanawha River produced thirteen species of unionid clams. Large populations of Corbicula manilensis were also found. Although suitable habitat was found throughout the drainage, clams were found in only the upper reaches of the river. Possible explanations for the absence of clams downstream are industrial and urban pollution and habitat modification for navigational purposes.

Morris, S. and R. D. Purchon. 1981. The marine shelled Mollusca of west Malaysia and Singapore 3. Bivalvia. Journal of Molluscan Studies 47(3):322 327.

Mortillet, G. de. 1863. Coquilles terrestres et d'eau douce des sables blancs à Elephas primigenius et à silex taille'es d'Abbeville. Bulletin de la Société Géologique de France, serie 2, 20:293 295.

Morton, B. 1970. The evoltion of the heteromyarian condition in the Dreissenacea (Bivalvia). Palaeontology 13(4):563 572.

Inspection of the valves of living members of the Corbiculacea (including Corbicula sp.) and Dreissenacea and fossil Dreissenacea in the collections of the British Museum (Natural History) has revealed that the evolution of the heteromyarian form in present day Dreissenacea in all probability arose from an established isomyarian corbiculid stock. Descriptions of the taxa are given, and the stages in the evolution of the Dreissenacea discussed.

Morton, B. 1973. Some aspects of the biology and functional morphology of the organs of feeding and digestion of Limnoperna fortunei (Dunker) (Bivalvia: Mytilacea). Malacologia 12(2):265 281.

It is suggested that Limnoperna could emulate the rapid expansion of range experienced by Dreissena polymorpha in Europe and Corbicula manilensis in North America. For this reason pertinent aspects of the functional morphology and biology of Limnoperna have been investigated. Comparisons have been made with other mytilids, and with Dreissena which Limnoperna superficially resembles. The possibility of a phylogenetic affinity between these two species is discounted; the similarities being due to convergent evolution and the adoption of similar habits. The evolution of the heteromyarian condition in the Mytilacea and Dreissenacea, followed by the subsequent evolution of osmoregulating powers, has enabled Limnoperna and Dreissena to successfully invade the hard surfaces of freshwater systems. In this habitat there is no competition from the specialized infaunal bivalves characteristically found in fresh waters. The colonization of this habitat has conflicted with Dreissena, and may possibly conflict in the case of Limnoperna, with the interests of man in the supply of fresh water.

Morton, B. 1973. Analysis of a sample of Corbicula manilensis Philippi from Pearl River, China. Malacological Review 6:35 37.

A morphometrical analysis of Corbicula sp. imported from the Pearl River at Canton, China, into the produce markets of Hong Kong is reported. It was noted that most of the shells had three growth rings (although one specimen had eight). It was suggested that some form of conservation is practiced in the culture of these bivalves in China. A discussion of growth and reproductive periods is given and compared with those of United States populations of these bivalves.

Morton, B. 1975. The diurnal rhythm and the feeding responses of the southeast Asian mangrove bivalve Geloina proxima Prime, 1864 (Bivalvia: Corbiculidae). Forma et Functio 8:405 418.

Morton, B. 1975. The colonisation of Hong Kong's raw water supply system by Limnoperna fortunei (Dunker 1857) (Bivalvia: Mytilacea) from China. Malacological Review 8:91 105.

The colonization of parts of Hong Kong's increasingly sophisticated water supply system by the fouling bivalve mollusc Limnoperna fortunei has been correlated with a change in the source of supply in 1965 by the Chinese authorities who augment Hong Kong's total water requirements. Such a change involved the utilization, for the first time, of raw water from the east River, itself a tributary of the Pearl River which is known to be naturally colonized by Limnoperna. The fouling potential of Limnoperna is assessed both in terms of Hong Kong and southern China and in terms of the possible introduction of Limnoperna to other continental land masses. A warning is given against such accidental introduction. Comparisons of this introduction and its consequences are made with Corbicula manilensis in the United States.

Morton, B. 1976. The biology and functional morphology of the southeast Asian mangrove bivalve Polymesoda (Geloina) erosa (Solander, 1786) (Bivalvia: Corbiculidae). Canadian Journal of Zoology 54:482 500.

The Southeast Asian mangrove is inhabited by a number of bivalves one of which, Polymesoda (Geloina) erosa (Solander, 1786), is widely distributed; it occurs on the landward fringe, in fetid pools of water formed at the bases of the mangrove trees. It is covered only by spring tides and at other times is inundated by rainwater draining through the mangrove from the land. G. erosa can withstand periods of exposure, during which time it can use subterranean water contained in the burrow. Any particles present in this water can be taken into the mantle cavity via the pedal gape and so into the alimentary canal. This is an extreme adaptation to a semiterrestrial mode of life. Aerial respiration is also achieved via the mantle margin. The functional morphology of G. erosa is described and related to the animal's life in the mangrove. The morphological adaptations of Geloina are also compared with those of other bivalves [including Corbicula fluminalis and Corbicula fluminea], particularly the Dreissenacea to which the Corbiculacea are possibly closely related.

Morton, B. 1977. The population dynamics of Corbicula fluminea (Bivalvia: Corbiculacea) in Plover Cove Reservoir, Hong Kong. Journal of Zoology (London) 181:21 42.

Various aspects of the biology, population dynamics, growth, sexuality, reproduction, settlement and mortality of populations of Corbicula fluminea inhabiting Plover Cove reservoir and the Shum Chuen River, Hong Kong, are described. These data are correlated with the hydrological picture of the reservoir to obtain a better understanding of the conditions under which the processes of growth, reproduction and settlement occur. An analysis of the shell dimensions of the component age groups comprising the population is obtained and, using the growth formula of Bertalanfy, the maximum theoretical length of C. fluminea for this locality is calculated, which, when considered in conjunction with other data relevant to the biology provides a more meaningful definition of the species. Such information, if obtained for other species, would provide a better taxonomic picture of the Corbiculacea as a whole and permit a greater understanding of those corbiculids introduced into the U.S.A. which are a pest of water supply systems. A preliminary comparison with such information as is available from the North American populations of Corbicula, indicates that at least two species, namely Corbicula fluminea and Corbicula fluminalis have been introduced. Other species may have been introduced, but until a more thorough examination of the species within their home and introduced ranges has been undertaken, the taxonomic picture will remain obscure.

This paper demonstrates that in Hong Kong C. fluminea is a protandric consecutive hermaphrodite, which incubates its young in a ctenidial marsupium. This refutes the conclusion reached by earlier researchers and emphasizes the need for more detailed studies.

Morton, B. 1977. The hypobranchial gland in the Bivalvia. Canadian Journal of Zoology 55(8):1225 1234. [English with French summary]

The hypobranchial gland of the protobranchs Nucula nucleus and Solemya parkinsoni comprises mucus cells flanked by inversely conical and ciliated regenerative cells. A similar structure occurs in the filibranch Monia squama and in the eulamellibranchs Fimbria fimbriata and Corbicula fluminea except that in the latter two the conical cells are not ciliated and in C. fluminea they are also secretory. The primitive function of the hypobranchial gland was the consolidation, in a mucus stream, of waste material for expulsion via the exhalant aperture. The evolution of the filibranch and eulamellibranch ctenidia dividing the mantle cavity into infrabranchial and suprabranchial chambers with waste material removed via the inhalant aperture abrogated the need for such a structure. It has been retained in some filibranchs where the ctenidia are possibly less efficient. In Nucula delphinodonta the hypobranchial gland secretes a brood pouch attached to the shell. Enhancement of this function in lamellibranch bivalves, notably C. fluminea and possibly F. fimbriata, has resulted in the gland functioning as an organ for the nutrition of developing larvae incubated in the suprabranchial chamber. An epithelium with regenerative cells of different structure occurs in the similarly incubatory Sphaerium corneum.

Morton, B. 1977. The population dynamics of Lymnoperna fortunei (Dunker, 1857) (Bivalvia: Mytilacea) in Plover Cove Reservoir, Hong Kong. Malacologia 16:165 182.

The mytilid Limnoperna fortunei is, usually, an inhabitant of freshwater rivers and streams in China and southeast Asia. In the late 1960's it was found to have colonized, in large numbers, Plover Cove, Hong Kong's largest and newest reservoir, recently reclaimed from the sea. In Europe, the dreissenid Dreissena polymorpha is a pest in reservoirs and their associated systems, and necessitates the widespread use of chlorine as an antifouling measure. This study was undertaken principally to determine the potential threat of Limnoperna to the water supply system of Hong Kong.

Long term experimental information obtained upon the time of breeding and settlement, the rate of growth and life span of Limnoperna and these data are correlated with the seasonal hydrology of the reservoir, from its inception.

The potential threat of Limnoperna is evaluated and a warning given against the possible artificial introduction of this species into other parts of the world, as has happened with Dreissena polymorpha in Europe and Corbicula manilensis into the United States of America with disastrous consequences. The latter species probably also came from China.

Morton, B. 1977. The occurrence of inflammatory granulomas in the ctenidial marsupium of Corbicula fluminea (Mollusca: Bivalvia): A consequence of larval incubation. Journal of Invertebrate Pathology 30(1):5 14.

A number of tumor like cysts in the ctenidia of Corbicula fluminea are described. The cysts result from the encapsulation of incubated larvae within the female inner demibranchs which are modified to form a marsupium. Corbicula fluminea is a protandric consecutive hermaphrodite, and larval incubation commences with sex reversal and the release of the first eggs. For some reason a few of the larvae are not released, and their retention and subsequent death results in the mobilization of the innate cellular defensive mechanism of the parent. This process involves, initially, an invasion of epithelioid cells and amoebocytes (granulocytes), resulting in hyperplasia. This is followed by structural changes to the epithelium bordering the interlamellar spaces (within which the larvae are incubated) to form ultimately the cyst wall. The epithelium is surrounded externally by layers of fibroblasts which eventually form a thick capsule. The autolyzed larval tissues are themselves invaded by fibrocytes, epithelioid cells, and amoebocytes and, in one specimen, had formed a three layered capsule within the surrounding capsule. The amoebocytes probably reabsorb the larval cellular debris. This unusual example of a molluscan cellular defensive mechanism may assist in the diagnosis and separation of hyperplastic injury responses from neoplastic conditions in invertebrates.

Morton, B. 1979. Freshwater fouling bivalves. IN: Proceedings of the First International Corbicula Symposium, J. C. Britton, Ed. Texas Christian University Research Foundation (Ft. Worth). pp. 1 14.

The industrial revolution, first in Europe and later in the United States, resulted in the planned development of standing and running bodies of fresh water for transport (canals), cooling and diluting industrial plants and wastes respectively and, with concomitant urbanization, for domestic purposes. Associated with man's utilization of the freshwater domain has arisen concomitant problems of bio fouling, particularly with regard to the bivalved molluscs.

First encountered with Dreissena polymorpha in Europe and later by Corbicula, introduced from Asia, in North America, the spread of these foulers has matched water resource development. The prerequisites essential for the successful colonization of artificial waterways by these bivalves are discussed and their spread is described and accounted for especially with regard to Dreissena and Corbicula. Other potential freshwater pests such as Limnoperna fortunei in China, Mytilopsis sallei and Modiolus striatulus in India and a number of species of Mytilopsis (Dreissenidae) in various parts of the world are identified.

The impact of freshwater bivalves upon both the natural and man made freshwater environment is discussed and the various methods of control available are described. It is concluded that the problems associated with such bivalves will increase globally as water becomes a more valuable and less available resource. Most of the foulers possess a wide niche diversity which adversely affect man's equally diverse activities in the freshwater environment. They colonize standing bodies of water but are also successful where they obtain access to the cooling systems of fossil or nuclear fueled power stations.

The ecological implications of such introductions are no less important and, with infaunal species, competition with the endemic bivalve fauna is a serious problem. This is especially true of Corbicula in North America, but less so of epifaunal byssally attached foulers colonizing the upper surface of solid substrates. Conversely, however, such introductions have the potential to teach us much of ecological processes in action.

Morton, B. 1979. Corbicula in Asia. IN: Proceedings of the First International Corbicula Symposium, J. C. Britton, Ed. Texas Christian University Research Foundation (Ft. Worth). pp. 15 38.

The taxonomy of the Corbiculacea, notably with regard to the Corbiculinae is in disarray. This is particularly true of the genus Corbicula, where many hundreds of species are reportedly extinct. Müller described three species from Asia, namely; Corbicula fluminalis, Corbicula fluviatilis, and Corbicula fluminea. By general consent, Corbicula fluminea is considered synonymous with Corbicula fluviatilis, the former name having nomenclatural precedence.

In the 1920's, B. Prashad revised the genus Corbicula and decided upon 69 valid species from Asia (excluding Australia). An extremely critical analysis of Prashad's researches has been here undertaken and the results indicate that most of these so called species are but subspecies, geographic varieties, ecotypes or just plain unusual specimens of the highly polymorphic, widely distributed C. fluminea. Other specimens can be assigned to different genera including Polymesoda and Batissa wilst a few others are probably referable to C. fluminalis which has been hitherto assumed to have a middle Asian but not far Asian distribution.

Modern researches in Japan have further confused the taxonomic picture of Corbicula, but again it is felt that the Japanese species of this genus might also be referable to C. fluminea and C. fluminalis. New species of Corbicula are still being described from Asia; such unwarranted nomenclatural hair splitting, based on shell characters alone, is thoroughly irresponsible.

A species of Corbicula has also been introduced into North America. The available evidence suggests that this is C. fluminea though the possibility remains, again in the absence of sound data and a confused taxonomy, that a second, larger species may also have been introduced.

A solution to Corbicula taxonomy cannot come through a study of shells; species determination in this genus must rest upon co ordinated behavioral, ecological, morphological, physiological, biochemical and genetic studies.

Morton, B. 1982. Some aspects of the population structure and sexual strategy of Corbicula cf. fluminalis (Bivalvia: Corbiculacea) from the Pearl River, Peoples Republic of China. Journal of Molluscan Studies 48(1):1 23.

The Pearl River around Canton, Kwangtung Province, China is the site of the clam fishery based on a species of Corbicula (Veneroida: Corbiculidae) referred to by Miller and McClure (1931) as Corbicula manilensis Philippi. This name is, however, unavailable being a junior synonym of another widely distributed Asian species, principally of streams: Corbicula fluminea (Müller). The Pearl River species is probably referable to Corbicula fluminalis (Müller), the type of which it closely resembles. Many hundreds of Corbicula spp. have been described from Asia alone but it has been argued elsewhere (Morton, 1979) and is here reiterated that probably all of these species are referable to C. fluminea and C. fluminalis, hough in the latter case, because the species is generally assumed to have a middle Asian distribution, this is uncertain. An earlier study showed that C. fluminea is a small, rounded species which lives for but 2 3 yrs, produces two growth rings per annum, spawns twice a year in spring and late summer when temperatures are high, is a protandric hermaphrodite, and incubates fertilized eggs to a length of 220 micrometers within the inner demibranchs which possess special glands. In contrast, C. cf. fluminalis is large, triangular, lives for up to 10 yrs produces 1 growth ring per annum, spawns once a year in winter when temperatures are cold, and does not incubate fertilized eggs within the inner demibranch even though ctenidial glands do develop in young individuals. The sexual strategy in C. cf. fluminalis is complex. Basically the species is dioecious, with a small percentage (4.5%) of simultaneous hermaphrodites, but the dioecious specimens show a general trend toward protogynous hermaphroditism with a greater percentage (60%) of males for 8 yrs. This strategy probably allows expression of different kinds of sexuality in different environmental situations and provides a clue to the underlying basis for different sexual strategies recognized in other, principally freshwater and estuarine bivalves; e.g., Ostrea virginica, C. fluminea and Anodonta cygnea. Ctenidial glands were possibly a necessary pre adaptation in the Corbiculacea facilitating colonization of lotic niches.

Morton, B. 1983. The sexuality of Corbicula fluminea (M:uller) in lentic and lotic waters in Hong Kong. Journal of Molluscan Studies 49(1):81 83.

Lotic populations demonstrated 52.1% females and 47.9% hermaphrodites. No males were found. In lotic waters, 29.5% were male, 39.3% were female, and 31.2% were hermaphrodites. Maleness appears to selected against in lotic situations.

Morton, B. 1983. Mangrove bivalves. IN: The Mollusca, Vol. 6, Ecology, W. D. Russell Hunter, Ed. Academic Press (New York). pp. 77 138.

A world wide review of the biology and ecology of mangrove bivalves is presented. Brief references to bivalves in the genus Corbicula are made in comparison with other members of the Corbiculidae indigenous to mangrove habitats.

Morton, B. 1986. Corbicula in Asia   an updated synthesis. IN: Proceedings of the Second International Corbicula Symposium, J. C. Britton, Ed. American Malacological Bulletin Special Edition No. 2. pp. 113 124.

A previous review of Corbicula in Asia came to the tentative conclusion that there are but two species. This resulted from analysis of early conchological assessments of the genus. This review is of contemporary conchological literature but relies principally on the researches of biologists who have collectively defined the species concerned. It is reasserted that two species are predominant. Corbicula fluminalis (Müller) occurrs in estuaries and tolerates salinities up to 50 ppt. It is dioecious with a trend toward protogyny. Corbicula fluminea (Müller) is freshwater with only a limited tolerance of low (15 ppt) salinities. This smaller species (a shell length of up to 35 mm in southern China) is dioecious. Corbicula fluminea has been introduced into North America.

Morton, B. 1987. Comparative life history tactics and sexual strategies of the fresh and brackish water bivalve fauna of Hong Kong and Southern China. American Malacological Bulletin 5(1):91 99.

Relatively few bivalve species inhabit the various components of the fresh and brackish water environment of southern China, including Hong Kong. Of these, the Corbiculacea are the most diverse, accounting for seven of the 11 known species. Three unionids occur in southern China but only one, Anodonta woodiana, is found in Hong Kong. The Mytilidae are uniquely represented by the freshwater Limnoperna fortunei.

Hong Kong habitats are relatively diverse resulting from proximity to the Pearl River estuary and to the establishment of man made habitats, i.e. reservoirs and slow flowing agricultural ditches and furrows. Two species groups, both definable as K selected, respectively colonize large permanent lotic or lentic habitats or small lentic environments with predictable perturbations. Representatives of the former are typically dioecious (there also being a greater proportion of females and small percentage of hermaphrodites), long lived (> 10 yrs), with one reproductive season each year which can be correlated with major seasonal climatic and hydrological events. They are iteroparous and non brooding, except for Anodonta woodiana. An opposite situation is seen in occupants of small lentic, relatively stable habitats in which the effects of seasonal drying are more pronounced and yet still "predictable". These species are typically small, short lived (< 1 yr), simultaneous hermaphrodites, generally semelparous and with brooding and reproductive timing correlated less with major climatic events, than with locally important environmental perturbations, probably permitting great interpopulation variability.

A third category of bivalves, typified locally by Corbicula fluminea, and to a lesser extent Limnoperna fortunei, lives for two to three years and can be broadly defined as r selected species. These occupy a wide range of lotic and lentic, and perennial and ephemeral habitats often with unpredictable major perturbations. In the case of C. fluminea, a variety of sexual expressions are assumed in different habitats and fertilized eggs are ctenidially brooded. This species is polymorphic with regard to shell form and color and, most important, sexual expression. It is believed that high genotypic variability and phenotypic plasticity may characterize this hitherto little studied category of highly opportunistic and recent bivalve colonists of the freshwater domain, accounting not only for their success but also the plethora of species names attributed to them.

Morton, B. 1987. Polymorphism in Corbicula fluminea (Bivalvia: Corbiculoidea) from Hong Kong. Malacological Review 20:105 127.

In Hong Kong (and North America), Corbicula fluminea exists as two distinct ecomorphs   the more usual straw colored for A and a dark form B. A 14 month comparison of water quality parameters has been undertaken in Hong Kong at two streams with two stations each and where different populations of the two ecomorphs occur.

Different ecomorphs occurring in the same stream have approximately similar shell forms which are different from those of the same ecomorphs at the second stream. These can be related to inter stream differences in the water quality parameters of temperature and hardness.

The various distributions of the color morphs of Corbicula fluminea appear related to inter station differences in water quality parameters of pH, dissolved oxygen and carbon dioxide and, especially, potassium. Color polymorphism is also associated with differences in sexual expression. Form A individuals are predominantly female, form B individuals are predominantly hermaphroditic. The question of whether or not C. fluminea exists as two ecomorphs or, as suggested by some North American workers, two species, is resolved by the occurrence of a third morph (I) intermediate in color between A and B, but with sexual characteristics of form B. It is concluded that C. fluminea is a highly variable species, shell form, color and expression of sexuality resulting from environmental induction.

Morton, B. 1991. Do the Bivalvia demonstrate environment-specific sexual strategies? A Hong Kong model. Journal of Zoology 223(1):131-142.

The expression of sexuality, overall sex ratio and variation in sex ratio with age of 14 southern Chinese freshwater, brackish and marine bivalves have been investigated. Freshwater species are often hermaphroditic and brooding, e.g. Muscalium and Pisidium (Pisidiidae), while Corbicula fluminea (Corbiculidae) demonstrates wide intraspecific variability in sexual expression, but also broods. Anodonta woodiana (Unionidae) and Limnoperna fortunei (Mytilidae) are dioecious. Mangrove and brackish water species are all dioecious (except Saccostrea cucullata) with a slight male-biased sex ratio overall, but are strongly male-biased as juveniles. The marine intertidal species, Perna viridis (Mytilidae) and Donax semigranosus (Donacidae) have a stable 1:1 sex ratio. Although intraspecific variations in life history tactics and sexual strategies equip all species for a variable environment, it is postulated that permutations of the "dioecious" condition, mediate through variations in sex ratio either overall or with age, broadly equip the Bivalvia for the total range of aquatic habitats.

Morton, B. 1996. The aquatic nuisance species problem: A global perspective and review. IN: Zebra Mussels and other Aquatic Nuisance Species, Chapter 1, F. Diitri, Ed. .Ann Arbor Press (Michigan). pp. 1-54

Morton, B., and K. Y. Tong. 1985. The salinity tolerance of Corbicula fluminea (Bivalvia: Corbiculoidea) from Hong Kong. Malacological Review 18(1 2):91 95.

The salinity tolerance of Corbicula fluminea was tested by assessing mortality, tissue chloride and body water content in salinities ranging from 0.03 to 34.5 ppt. At salinities below approximately 13.0 ppt, C. fluminea can osmoregulate, maintaining fairly constant tissue chloride levels for periods of up to seven days, with little mortality. At higher salinities, C. fluminea osmoconforms and mortality progressively increases with salinity and time. These data correlate well with those obtained for C. fluminea elsewhere, notably the United States, where this species has been introduced. A less conclusive correlation is made with data obtained for Corbicula leana from Japan.

Moser, E. B. 1997. Use of the Comet assay and metallothionein assay as biomarkers of stress in the Asiatic clam, Corbicula fluminea, at a metals-contaminated hazardous waste site. Master of Science Thesis, California State University (Long Beach). ix + 97 pp.

Mothersill, J. S., R. Freitag and B. Barnes. 1980. Benthic macroinvertebrates of northwestern Lake Victoria, east Africa: abundance, distribution, intra phyletic relationships between taxa and selected element concentrations in the lake bottom sediments. Hydrobiologia 74(3):215 224.

The dominant benthic macroinvertebrate taxa found in northwestern Lake Victoria were the gastropods Melania tuberculata Müller and Bellamya sp., the insects chironomid species and Chaoborus sp., the pelecypod Corbiculina sp. and an unidentified oligochaete. The common taxa associations comprise the pelecypod Caelatura sp. with the gastropod Bellamya sp. and the pelecypod Corbiculina sp. with the gastropods M. tuberculata and Bellamya sp. and chironomid species commonly occurred in sediments having relatively high concentrations of Zn and Cu and the unidentified oligochaetes with sediments rich in Fe, Co, and Zn.

Moulton, C. A., W. J. Fleming and C. E. Purnell. 1992. Methods and criteria for diagnosing anticholinesterase poisoning in fresh-water bivalves. 13th Annual Meeting Society of Environmental Toxicology and Chemistry, Cincinnati, Ohio, 8-12 November. Abstracts.

In August, 1990, a die-off of the endangered Tar River Spiny Mussel (Elliptio steinstansana) occurred in Swift Creek adjoining agricultural land in Nash County, North Carolina. Failing to find pesticide residues in the mussels, their adductor muscle was analyzed and a 65 to 73% reduction in cholinesterase (ChE) activity was found compared to an upstream reference site. Lacking specific criteria for interpreting this finding, a static, 96 hr EC50 test was conducted to determine the sensitivity of a freshwater mussel (Elliptio complanata) to ChE inhibitors and to determine ChE activity levels diagnostic of exposure and mortality. Additionally, a freshwater clam (Corbicula fluminea) was subjected to identical tests to determine its suitability as a surrogate test species for freshwater mussels. Adult specimens of each species were used in the tests. Although we used adductor muscle for ChE assays of the mussel, the small size of the clam required that all of the soft tissue components be homogenized for the assay. We make specific recommendations for diagnosing anti-ChE exposure in freshwater bivalves and discuss potential use of mussels and clams in pesticide biomonitoring programs.

Moulton, C. A., W. J. Fleming and C. E. Purnell. 1996. Effects of two cholinesterase-inhibiting pesticides on freshwater mussels. Environmental Toxicology and Chemistry 15(2):131-137.

The freshwater mussel Elliptio complanata and the Asiatic clam Corbicula fluminea were exposed for 96 h at 21^oC to aldicarb, a carbamate pesticide, and acephate, an organophosphate pesticide. Test pesticide concentrations ranged from 0 to 320 mg/L. We found no mortality under these conditions. Relative to controls, cholinesterase (ChE) activity in adductor muscle from E. complanata was significantly depressed at concentrations as low as 0.1 mg aldicarb/L and 1.3 mg acephate/L. Higher pesticide concentrations were required to inhibit ChE activity in whole bodies of C. fluminea than in adductor muscle of E. complanata. Raising the experimental temperatures from 21 to 30^oC increased pesticide-induced mortality, with mussels dying at aldicarb or acephate concentrations of only 5 mg/L. Cholinesterase activities of adductor muscle depressed 94 to 96% relative to controls began to recover within 2 and 12 d, but they were not fully recovered for 12+ and 24+ d following aldicarb and acephate exposures. Both aldicarb and acephate at 5 mg/L reduced shell closure responsiveness of mussels, with more pronounced effects observed at 27 ^oC than at 21^oC. The data support the usefulness of determining ChE activity in adductor muscle to identify the exposure of freshwater mussels to ChE-inhibiting pesticides.

Mousson, M. A. 1848. Über die Land  und Süsswasser Mollusken von Java. Mitteilungen der Naturforschenden Gesellschaft in Zurich 1:264 273.

Mousson, M. A. 1849. Die Land  und Süsswasser Mollusken von Java. F. Schulthess (Zurich). 126 pp.

Mousson, A. 1854. Coquilles terrestres et fluviatiles, recueillis par M. le Prof. Bellardi dans un voyage en Orient. Mittheilungen der Naturforschenden Gesellschaft in Zürich 3:362 402.

Mousson, A. 1861. Coquilles terrestres et fluviatiles recueillis par M. le Prof. J. R. Roth dans son dernier voyage en Palestine. J. Rothschild (Paris). 68 pp.

Mousson, M. A. 1874. Coquilles terrestres recueillies par M. le Dr. Alexandre Schlaefli en orient. Journal de Conchyliologie 22:1 60.

Mouthon, J. 2000. Repartition du genre Corbicula Megerle von Mühlfeld (Bivalvia: Corbiculidae) en France a l'aube du 21e siecle [Distribution of Corbicula Megerle von Mühlfeld (Bivalvia; Corbiculidae) in France at the beginning of the 21st century]. Hydroecologie Appliquee, Paris 12(1-2):135-146. [French with English summary]

The freshwater bivalve Corbicula fluminea was introduced in France in 1980 in the Dordogne estuary. Since that time, this species has succeeded in colonizing a large number of rivers belonging to four main drainage basins: the Garonne, the Rhone, the Loire and the Seine, as well as the French part of the Rhine basin. Canals have played an important role in the spreading of Corbicula, as was the case for Dreissena polymorpha in the 19th century. [Corbicula fluminea a ete decouvert pour la premiere fois en France en 1980 dans l'estuaire de la Dordogne. Depuis cette date, ce bivalve a colonise un grand nombre de cours d'eau appartenant aux quatre grands bassins hydrographiques de la Garonne, du Rhone, de la Loire et de la Seine ainsi que la partie francaise du bassin Rhenan. Les canaux ont joue un role preponderant dans la propagation des Corbicula comme ce fut le cas pour Dreissena polymorpha au cours du 19e siecle.]

Mouthon, J. 2001. Life cycle and population dynamics of the Asian clam Corbicula fluminea (Bivalvia: Corbiculidae) in the Rhone River at Creys-Malville (France). Archiv für Hydrobiologie 151(4):571-589.

The Corbicula fluminea population in the Villebois Reservoir located on the French Upper Rhone, was sampled every month from September 1996 to December 1999. These populations are characterized by: a single annual reproduction period that starts during July after the floods caused by melting snow and ends in September; slow growth varying considerably from one year to the next; a growth period that extends from July-August to September-October and which only starts for most of the juveniles on the year after their birth; a life span of 5 years. The hydraulic developments constructed by the Compagnie Nationale du Rhone have considerably favored the colonization of the Upper Rhone by Corbicula. Nonetheless, this sector of the river is affected by major variations of flow and temperature following the snow melt, as well as hydropower generation, leading to a stressful environment for C. fluminea. However, it is above all the low quantities of available food, especially chlorophyll-a which are responsible for the low annual growth rate of individuals and probably the low recruitment observed in 1998 and 1999.

Mouthon, J. 2001. Life cycle and population dynamics of the Asian clam Corbicula fluminea (Bivalvia: Corbiculidae) in the Saone River at Lyon (France). Hydrobiologia 452(1-3):109-119.

The Corbicula of the Saone at Lyon were sampled every month from September 1996 to December 1999. These populations are characterized by a single annual reproduction period starting in May or June and ending in September or October in which two peaks of intensity can be distinguished; the presence of one or more cohorts according to year; low growth in spite of a growth period that generally lasts from March to October; and a lifespan of about 5 years. Although the effect of toxic substances can be considered, it appears that the reason for the low recruitment levels observed from 1997 to 1999 are above all due to the small quantities of food available, especially chlorophyll a.

Mouthon, J. 2003. Longitudinal and temporal variations of density and size structure of Corbicula fluminea (Bivalvia) populations in the Saone and Rhone rivers (France). Annales de Limnologie /International Journal of Limnology 39(1):15-25.

Mouthon, J. and T. Parghentanian. 2004. Comparison of the life cycle and population dynamics of two Corbicula species, C. fluminea and C. fluminalis (Bivalvia: Corbiculidae) in two French canals. Archiv für Hydrobiologie 161(2):267-287.

Two Corbicula species (C. fluminea and C. fluminalis) were sampled every month in two canals in central France from December 2001 to May 2003. The C. fluminea populations were characterized by (1) a reproduction period that started in March and ended in September-October, during which two peaks of intensity could be distinguished, the first occurring in June and the second in August, the latter corresponding to a density peak, (2) the production of two generations per year, (3) the presence of five cohorts, (4) longevity from 2.5 to 3 years, and (5) a maximum shell length that may exceed 36 mm. In the Loire Lateral Canal, a second period of reproduction was observed during the winters of 2002 and 2003. However, since the number of larvae incubated was always low, we hypothesise that gravid individuals are in fact cryptic hybrids. The C. fluminalis populations were characterised by (1) two reproduction periods, the first occurring in winter during which the number of larvae incubated was low, while the second extended from March to October, reaching its maximum intensity in June and July though the corresponding peak of density did not occur until December, (2) the presence of four cohorts, (3) longevity of four years, a maximum length of 24 mm, a slower growth than that of C. fluminea, and (4) higher sensitivity to freezing. Sudden falls in chlorophyll-a concentrations may play a role in triggering the incubation and spawning periods of this species.

Mudkhede, L. M. and R. Nagabhushanam. 1977. Heat tolerance of the fresh water clam, Corbicula regularis. Marathwada University Journal of Science, Natural History 16(9):151 154.

The freshwater clam, Corbicula regularis, taken from an environment whose temperature was 27±1^oC, did not survive for 24 hr at 38^oC. The 24 hr median heat tolerance limit was 37.2^oC. On acclimation to low (18±l^oC) and high 31±1^oC) temperatures for 2 days, the 24 hr median heat tolerance shifted to 34.7^oC and 37.75^oC, respectively.

Mueller, W. E. G., S. Riemer, B. Kurelec, N. Smodlaka, S. Puskaric, B. Jagic, G. Mueller-Niklas and N. V. Queric. 1998. Chemosensitizers of the multixenobiotic resistance in amorphous aggregates (marine snow): Etiology of mass killing on the benthos in the Northern Adriatic? Environmental Toxicology and Pharmacology 6(4):229-238.

Periodically appearing amorphous aggregates, “marine snow”, are formed in the sea and if settled as mats on the sea bottom cause death of benthic metazoans. Especially those animals are killed which are sessile filter feeders, e.g. sponges, mussels, or Anthozoa. The etiology of the toxic principle(s) is not yet well understood. Gel-like marine snow aggregates occurred in the Northern Adriatic during summer 1997. Samples of these aggregates were collected during the period July to September and the outer as well as the inner zones were analyzed for (i) cell toxicity, and (ii) chemosensitizing activity of the multixenobiotic resistance (MXR) mechanism. Organic extracts were prepared and cell toxicity was determined using mouse lymphoma cells. The experiments revealed that the major activity is seen in the center of the mats of the gel-like aggregates; a growth inhibitory activity of up to 54% (correlated to 5 ml of snow sample) was determined. The same extracts were used to determine the inhibition of the P-glycoprotein (Pgp) extrusion pump which confers the multixenobiotic resistance. The analyses were performed with cells from the sponge Suberites domuncula and with gills from the clam Corbicula fluminea in situ. Both systems have been shown to express the Pgp extrusion pump. The data show that extracts from the outer zone of the gel-like aggregate samples display pronounced inhibitory activity on the MXR extrusion pump and hence act as chemosensitizers by reversing the MXP property. These findings indicate that gel-like aggregates contain compounds in the outer zone, chemosensitizer of the Pgp extrusion pump, which lower the level of protection of metazoan animals towards dissolved compounds in their surrounding milieu, and in the center toxic compounds which are--very likely--even in the absence of chemosensitizers hazardous for the invertebrates.

Mühlfeld, J. K. Megerle von. 1811. Entwurf eines Neuen Systems der Schaltiergehause. Naturforschende Fruende zu Berlin 5:38 72.

The genus Corbicula is erected on page 56 and Corbicula fluminalis (Müller, 1774) is designated the genotype.

Müller, O. F. von. 1774. Vermium Terrestrium et Fluviatilum, seu Animalium, Infusorium, Helminthocorum, et Testaceocorum, non Sarinorum, Succincta Historia. Heineck and Faber, Havniae and Lipsiae 2:1 214. [Reprinted in Sterkiana, 69/70. 1977]

Murata, M. and M. Sakaguchi. 1990. Influence of the ethanol treatment on pHs of boiled meat extracts of fish, shellfish, and domestic animals. Nippon Suisan Gakkaishi/Bulletin of the Japanese Society of Scientific Fisheries 56(10):1697.

Boiled meat extracts from 13 species of fish, shellfish, and domestic animals were prepared and the influence of the ethanol treatment on pHs of these extracts was examined. Ethanol treatment of boiled meat extracts from carp, scallop, prawn, snow crab, oyster, Corbicula, and sea urchin gonad resulted in lowering pH from 0.5 to 1.3 unit. Boiled meat extracts from beef, pork, and chicken also showed a decline of pH around 0.9 unit. The lower pH values in the ethanol-treated extracts from all specimens strongly suggest that the treatment produces the decline of pH in aquatic as well as domestic animal meats. An extensive decline of pH is thought to have some influence on overall taste quality of the meat extracts.

Murray, H. D. 1971. New records of Corbicula manilensis (Philippi) in Texas. The Nautilus 85(1):35 36.

Murray, H. D. 1971. Fresh water mussels of Lake L. B. J., Texas. Bulletin of the American Malacological Union 1971:36 37.

Large populations of Corbicula manilensis are reported from Lake Lyndon B. Johnson, Colorado River system, Texas. All specimens were judged to be less than 5 years old.

Murray, H. D. 1978. Freshwater mussels of Lake Corpus Christi, Texas. Bulletin of the American Malacological Union 1978:5 6.

Murray, H. D. and E. C. Roy, Jr. 1968. Checklist of freshwater and land mollusks of Texas. Sterkiana 30:25 42.

Mussalli, Y. G., I. A. Diaz Tous, and J. B. Stickel. 1986. Asiatic clam control by mechanical straining and organotin toxicants. IN: Proceedings of the Second International Corbicula Symposium, J. C. Britton, Ed. American Malacological Bulletin Special Edition No. 2. pp. 83 88.