Corbicula an annotated bibliography 1774 2005

The general objective of our work was to propose new reference material for chemical toxicity testing and new sentinel organisms for environmental quality survey programs (freshwater or soils). A basic toxicological data on the environmental effects of uranium was provided. Thus, a comparative study was conducted to establish the acute toxicity and toxicokinetics of lead (Pb) and uranium (U) to the bivalve mollusc Corbicula fluminea and the terrestrial annelid Eisenia fetida andrei and to compare these findings with those of the well-known teleost fish Brachydanio rerio. The concentration of these metals were measured in various tissues of the clam and the worm after two periods of exposure (4 and 11 days) to identify the affinities of these tissues for Pb and U. Results have shown that Pb and U are very toxic to Eisenia and relatively nontoxic to Corbicula. By comparison, Pb was relatively nontoxic and U appeared to be very toxic to the fish. The toxicokinetic studies indicated that the three species are able to accumulate Pb and U, the rate and level of accumulation depending both on the species and the metal. It was also found that fish and clams depurate the two metals. Data collected for the worm were conflicting: Pb was not depurated whereas tissue concentrations of U declined after the eighth day of exposure. This study has also shown that the tissue distribution of Pb in the mollusc and in the earthworm differs significantly from that of U, both after 4 and 11 days exposure. In conclusion, these three species showed potential as bioindicators of environmental contamination by metals. Indeed, they could be used in conjunction to test different compartments of an ecosystem: worms for soils, fish for the water column, and clams for the water/sediment interface.

Lachner, E. A., C. R. Robins and W. R. Courtenay. 1970. Exotic fishes and other aquatic organisms introduced into North America. Smithsonian Contributions to Zoology No. 59:1 29.

The introduction and dispersal of Corbicula fluminea in United States waters is reviewed. Possible dispersal mechanisms are presented as well as a brief history of industrial facility fouling.

Lamarck, J. C. P. A. 1806. Annales de Muséum d'Histoire Naturelle Paris 8:420 421.

Cyclas chinensis is described.

Lamarck, J. C. P. A. 1818. Histoire Naturelle des Animaux sans Vertebres. Vol. 5. pp. 1 612.

Lamarck, J. C. P. A. 1835. Histoire Naturelle des Animaux sans Vertebres, 2nd. Edition, G. P. Deshayes, Ed. Vol. 6.

Lamy, E. 1913. Note sur le Cyclas australis Lamarck. Bulletin du Muséum d'Histoire Naturelle Paris 19:466 468.

Langdon, C. J. and C. L. Counts, III. 1983. Biogeographic analysis of Corbicula fluminea with emphasis on environmental factors that may limit successful larval development. IN: Mid Atlantic Region Research Planning Workshop, , W. S. Gaither, Ed. Electric Power Partners Program, University of Delaware College of Marine Studies (Lewes). pp. 42 43.

Lange de Morretes, F. 1949. Ensaio de catalogo dos moluscos do Brasil. Arquiros Museo Paranaense 7:5 216.

Latendresse, J. 1987. Mussels (Naiades): a renewable natural resource? IN: Proceedings of the Workshop on Die Offs of Freshwater Mussels in the United States, R. J. Neves, Ed. U.S. Fish and Wildlife Service, Upper Mississippi River Conservation Committee, and Virginia Polytechnic Institute and State University (Blacksburg). pp. 155 158.

It is speculated that the effects of Corbicula sp. on native bivalve populations will have negative affects on recruitment, abundance, and growth rates in some populations.

Lauritsen, D. 1984. Ammonium excretion by the Asiatic clam Corbicula fluminea. American Malacological Bulletin 3(1):101. [Abstract]

Ammonium excretion rates of Corbicula fluminea freshly collected from a eutrophic, coastal North Carolina river vary seasonally, with highest rates in summer. In areas of the river where they are abundant, clam excretion could supply from one third to one half of summer phytoplankton uptake of ammonium, when allochthonous loading to the river is at a minimum. Laboratory experiments show that with increasing food concentrations clams are ingesting increasingly more algal nitrogen, but ammonium excretion rates are highest at lower food concentrations. This suggests that at higher food concentrations, a greater percentage of the nitrogen ingested will be found in the clam's feces.

Lauritsen, D. D. 1985. Growth plasticity in the Asiatic clam Corbicula fluminea. Ecological Society of America and American Society of Limnology and Oceanography Joint Annual Meeting, Minneapolis, MN (USA), 17-21 June.

Lauritsen, D. D. 1985. Filter Feeding, Food Utilization, and Nutrient Remineralization by Corbicula fluminea (Bivalvia) and its Contribution to nutrient cycling in a North Carolina River. Ph.D. Dissertation, North Carolina State University (Raleigh). 134 pp.

Corbicula fluminea is quite prolific, and since it is a filter feeder, it can be expected to influence the cycling of nutrients within its habitat as a result of its feeding and excretory activities. Factors affecting filtration rates, food utilization, and excretion of metabolic wastes (ammonia and phosphate) were determined by laboratory experiments, and these physiological processes were then extrapolated to field estimates of C. fluminea found in the upper Chowan River, North Carolina, to obtain an estimate of the potential impact the clams can have on nutrient cycling in the river.

Corbicula fluminea filtration rates are low at winter temperatures, and many clams appear to be inactive during this season. Clam filtration rates were inversely related to food concentration although the total volume of food ingested increased significantly with increasing food concentrations. Extrapolation of clam size filtration rate relationships to a population of C. fluminea in the upper Chowan River indicate that the average number of clams found in a square meter of river bottom (350) could filter a volume of water equivalent to the overlying water column every 1 1.6 days in summer, depending on seston concentrations.

Clam filtration rates of four different ¹⁴C labeled algae species (two greens, a blue green, and a diatom) were similar, although partitioning of the ingested isotope showed significant differences between the algal foods. The diatom species was the most efficiently utilized by the calms, with more than 80% of the isotope ingested recovered in clam tissues.

Lauritsen, D. D. 1986. Assimilation of radiolabeled algae by Corbicula. IN: Proceedings of the Second International Corbicula Symposium, J. C. Britton, Ed. American Malacological Bulletin Special Edition No. 2. pp. 219 222.

Despite its abundance in many aquatic systems, little is known about the feeding biology of Corbicula fluminea. Because C. fluminea is now found in several coastal North Carolina rivers that have periodic summer blue green cyanobacterial blooms, this study compared the potential for the clams to use C 14 labeled cultures of the filamentous green algae Chlorella vulgaris and Ankistrodesmus sp. Although there were significant differences in the use of the algal foods by the clams, assimilation and net production efficiencies of clams fed the blue green were not significantly different from efficiencies of the two green algae. The significance was a result of the lower assimilation of Ankistrodesmus (47%, compared to 50% of Anabaena and 56% for Chlorella). Also, net production efficiencies were significantly higher for Ankistrodesmus (78%) than for other foods (61% for Anabaena and 59% for Chlorella).

Lauritsen, D. D. 1986. Filter feeding in Corbicula fluminea and its effect on seston removal. Journal of the North American Benthological Society 5(3):165 172.

Factors affecting filtration rates of Corbicula fluminea were studied in controlled laboratory experiments and the data were then used to illustrate the importance of clam filtering in a North Carolina river. Both temperature and food concentration significantly affected filtration rates. Rates measured at winter temperatures were significantly lower than summer rates, while food concentrations and filtration rates were inversely related. Filtration rates were compared among clams collected from several different habitats in North Carolina and although shell length (SL) dry flesh weight (DFW) relationships differed between locations, filtration rate size relationships were not significantly different when SL was used as a measure of clam size. Extrapolation of the above relationships to a population of C. fluminea in the upper Chowan River, North Carolina, indicated that the average number of clams in a square meter of river bottom (350) could filter a volume of water equivalent to the overlying water column (mean depth 5.25 m) every 1 1.6 days in summer, depending on seston concentrations.

Lauritsen, D. D. and S. C. Mozley. 1983. The freshwater Asian clam Corbicula fluminea as a factor affecting nutrient cycling in the Chowan River, N.C. Water Research Institute, University of North Carolina, Report No. 192. iii + 60 pp.

Lauritsen, D. D. and S. C. Mozley. 1989. Nutrient excretion by the Asiatic clam Corbicula fluminea. Journal of the North American Benthological Society 8(2):134-139.

The freshwater Asiatic clam, Corbicula fluminea (Müller) because of its abundance, has the potential to influence nutrient cycling by excretion of metabolic wastes, including NH₃ and PO₄. Excretion rates of ammonia and orthophosphate were estimated seasonally in Corbicula freshly collected from the Chowan River, a large coastal plain river in eastern Virginia-North Carolina. Excretion was expressed as a function of clam dry weight, and was highest in May and September for both nutrients. Using Corbicula population estimates from an earlier benthic survey of the Chowan to calculate excretion volumes per square meter suggests that the clams can have a substantial effect on nutrient cycling in summer in the upper Chowan River and a large tributary, the Blackwater River, with ammonia excretion ranging from 357 to 8642 μmoles m^-2 d^-1, and orthophosphate excretion ranging from 161 to 3924 μmoles m^-2 d^-1.

Laury, R. L. and C. C. Albritton, Jr. 1975. Geology of Middle Stone Age archaeological sites in the Main Ethiopian Rift Valley. Geological Society of America, Bulletin 86(7):999 1011.

Laville, A. 1898. Le gisement chell'eo moust'erien `a Corbicules de Cergy. Bulletin de la Société Anthropologique (Paris), 4e S'erie, 9.

Laville, A. 1899. Coups de poing avec talon et poig'ee r'eserv'es, disque, coin et dents d'Asiniens des couches `a Corbicules de Cergy. Bulletin de la Société Anthropologique (Paris), 4e S'erie, 10.

Lea, I. 1831. Observations on the naiads. Transactions of the American Philosophical Society 4:63 121.

Lea, I. 1834. Observations on the Genus Unio, I. 233 pp.

Leard, R. L. and B. J. Grantham. 1973. Organochlorine pesticide residues in selected freshwater Pelecypoda of Mississippi. Journal of the Mississippi Academy of Sciences 19:181. [Abstract]

Leard, R. L., B. J. Grantham and G. F. Pessoney. 1980. Use of selected freshwater bivalves for monitoring organo chlorine pesticide residues in major Mississippi stream systems. Pesticide Monitoring Journal 14(2):47 52.

Seven species of freshwater Pelecypoda, Amblema costata, Corbicula manilensis, Elliptio crassidens, Lampsilis claibornensis, Megalonaias gigantea, and Plectomerus dombeyanus were collected and monitored for pesticide content during 1972 and 1973. Thirteen collection sites, representing five major river basins in the state of Mississippi [Coldwater River, Sunflower River, Steel Bayou, Big Black River, Tombigbee River, Pearl River, Chunky River, Chickasawhay River, Leaf River, Pascagoula River, Black Creek] were sampled and compared. During the 24 month study, 26 water samples and 58 clam samples from the five basins were analyzed. Individual samples weighed from 8 g to 20 g and consisted of 1   30 clams, depending on size. Residues of toxaphene and methyl parathion were found only in 1973 water samples. The study shows that freshwater clams are effective monitors of pesticide content. The tendency of freshwater clams to concentrate pesticides and their corresponding ability to eliminate them varies with species. Significant reductions in DDT and a corresponding buildup of p,p' TDE were noted in 1973, following the limitations on the use of DDT and large scale flooding throughout the state.

Lee, E. H. and W. D. Heo. 1980. Taste compounds of Corbicula elatior. Bulletin of the National Fisheries University of Busan (Natural Sciences) 29(1):31 46. [English with English and Korean summaries]

Taste compounds including free amino acids, nucleotides and their related compounds, trimethylamine oxide, betaine and total organic acid in fresh meat, boiled meat and broth of Corbicula elatior were analyzed and the changes, distribution and their roles in taste were investigated.

The identified nucleotides and their related compounds were hypoxanthine, inosine, AMP, ADP, and ATP. The contents of hypoxanthine, inosine, AMP, ADP and ATP in fresh meat were 1.42 micromole/g, 0.27 micromole/g, 1.82 micromole/g, 1.74 micromole/g and 0.61 micromole/g, respectively; while 1.69 micromole/g, 0.25 micromole/g, 2.36 micromole/g, 2.19 micromole/g and 0.28 micromole/g, respectively in boiled meat. In broth, ADP and ATP were not detected and the contents of hypoxanthine, inosine and AMP were 0.11 micromole/g, 0.04 micromole/g, and 0.05 micromole/g, respectively.

Results of an omission test revealed the role of free amino acids was predominant in the taste of the clam followed by total organic acid and nucleotides and their related compounds, while those of TMAO and Betaine were not obvious.

Lee, H. H. and A. Lemma. 1992. Towards mitigation of zebra mussels and Asiatic clams: The use of endod, Phytolacca dodecandra. Journal of Shellfish Research 11(1):229.

Experiments using a static bioassay system as a basis to develop a focal control method for Dreissena and Corbicula illustrate the potential usefulness of plant molluscicides, Lemmatoxins, from Phytolacca dodecandra or Endod. Endod at a dose > 15 mg/L is lethal to adult zebra mussels and Asiatic clams, while at lower doses prevent adhesion and aggregation of the mussels. In addition to being noncarcinogenic and nonmutagenic, Endod is biodegradable. Since Endod plants have been successfully grown as culture, demands on large quantities of Endod usage in water intakes should stimulate further agricultivation. Since infestations of zebra mussels and Asiatic clams are long-term problems and waterworks vary in design and environment, a conceptual methodology for mitigation is suggested using Endod as the primary agent in combination with mechanical and chemical means to remove adult mussels and Asiatic clams from and to prevent aggregation in water intake pipes.

Lee, N. E., W. R. Haag and R. L. Jolley. 1981. Cooling water pollutants: Bioaccumulation by Corbicula. IN: Water Chlorination Impact and Health Effects, Vol. 4, Part 2, Environment, Health, and Risk, R. L. Jolley, et al., Eds. Ann Arbor Science Publishers. pp. 851 870.

Chemical analysis of tissue extracts derived from Corbicula manilensis collected from influent water supplies and chlorinated outfalls of electric generating plants has resulted in the identification of several classes of compounds. Some of the compounds are identified as priority pollutants and, as such, are of toxicological significance. Some are LCHs or LCH derivatives such as acids, esters, and alcohols, which may promote mutational and carcinogenic activity. Some fatty acid esters were identified as weak socarcinogens.

Fifty eight compounds were identified in tissue extracts of Corbicula manilensis taken from chlorinated outfalls at two coal fired steam plants, and 42 compounds were in the corresponding extracts of C. manilensis taken from the outfall in the Arkansas Nuclear One generating station. Approximately 39% of the identified compounds were common to two or more sampling sites and some were unique to an individual site, indicating a possible source of contamination not associated with antifoulant chlorine.

Ninety four compounds were identified in the tissue extracts of control Corbicula manilensis samples (not exposed to chlorine residuals) collected at the coal fired steam plant sites, and 46 compounds were in corresponding samples from Lake Dardanelle at Arkansas Nuclear One. Three of the compounds in tissue extracts of control C. manilensis collected at coal fired plant sites were halogenated, whereas four of those in samples collected from Lake Dardanelle appear to be chloroorganics. These results seem to imply that C. manilensis collected from influent water sampling sites could have been exposed to higher concentrations of chlorine (from unknown sources) than those collected from waters receiving antifoulant treatment chlorine residuals. No phthalates were found in clam tissues collected from Lake Dardanelle, but phthalates were present in water and sediment samples taken at the same time. Correspondingly, no phthalates were in clam tissues exposed to chlorine residuals from one coal fired plant collection site; however, they were found in the tissue controls from both coal fired plant sites. Although this study has been limited in the number of sampling sites used and in the number of analyses performed, the data indicate that C. manilensis bioaccumulate some toxic materials that could contribute to possible health effects in man. The population of C. manilensis is expanding in lakes, rivers, and streams across the United States and may be used for human consumption in some areas. In some Oriental countries, Corbicula spp. is already an economically important food source.

Only qualitative identification of compounds in the tissue extracts of Corbicula manilensis were done by this study; no quantitative comparisons were made, but concentrations of some of the compounds appear to exceed 1 ppm when compared to the pure compound standards used.

Lee, N. E., W. R. Haag and R. L. Jolley. 1983. Cooling Water Pollutants: Bioaccumulation by Corbicula. Water Chlorination: Environmental Impact and Health Effects, Vol. 4, Part 2, Environment, Health, and Risk. Ann Arbor Science (Ann Arbor, Michigan). pp. 851-870.

Samples of Corbicula, water, and sediment were collected in discharge areas of coal-fired and nuclear powerplants before and after chlorine exposure. About 50 compounds were qualitatively identified in Corbicula at each chlorinated outfall site, 39% of which were common to two or more sampling sites. Most of the compounds were carbohydrates, fatty acids, and hydrocarbons. Four chlorine compounds were listed. In the control Corbicula samples 94 compounds were identified. Several were halogenated. Phthalates were found at some sites. Data indicated that Corbicula accumulates toxic materials. However, the premise that chloroorganics are accumulated from the chlorinated antifoulants cannot be supported conclusively.

Lee, T. Y. and E. Y. Chung. 1980. Reproductive cycle of marsh clam Corbicula fluminea. Publications of Institute of Marine Sciences National Fisheries University of Busan 12:47 54. [Korean with English summary]

The histology of the gonads during gametogenesis and the reproductive cycle of the marsh clam, Corbicula fluminea, of Korean waters were studied by means of photomicrography. Monthly samples from brackish waters of Myungji and Hadan from March 1979 to February 1980. C. fluminea is dioecious, and ovoviviparous. The gonads are irregularly arranged from the sub region of the mid intestinal gland in the visceral cavity to the treticular connective tissue of the foot. The ovary is composed of a number of branched arborescent ovarian sacs. Oogonia actively proliferate along the germinal epithelium of the ovarian sac in which oocytes grow. The testis is composed of a number of seminiferous tubules, and the epithelium of the tubules functions like germinal epithelium along which the spermatogonia actively proliferate. A great number of undifferentiated mesenchymal and pigmented granular cells are abundantly distributed between the growing oocytes and spermatocytes in early development stages. With further development of the ovary and testis, three cells gradually disappear. Undifferentiated mesenchymal and pigmented granular cells are then considered to be related to the growth of oocytes and spermatocytes. After spawning, undischarged ripe eggs and spermatozoa remain in the ovary and testis respectively for some time. They finally degenerate and proliferation of new oogonia and spermatogonia occurs along the germinal epithelium of a newly formed gonad in the reticular connective tissue of the foot. The reproductive cycle of C. fluminea can be classified into five successive stages: multiplicative, growing, mature, spent, and degenerative stages. Spawning occurs from late June to October with a peak from August to September.

Lee, W. T. 1912. Coal fields of Grand Mesa and the West Elk Mountains. Bulletin of the U.S. Geological Survey, No. 510. 237 pp.

Corbicula cytheriformis (Meek and Hayden, 1860) is reported from the Bowie Shale member of the Mesaverde Cretaceous, 3 mi north of Paonia and 0.5 mi northwest of Paonia and Hubbard Creek, Colorado. Corbicula fracta (Meek, 1870) is reported from the Mesaverde Cretaceous 4 mi west of Meeker, Colorado. Corbicula occidentalis (Meek and Hayden, 1856) is reported from the Bowie Shale member of the Mesaverde Cretaceous 0.5 mi north of Bowie, Colorado. Alos, Corbicula sp. is noted from the Bowie Shale of the Mesaverde Cretaceous near Bowie, Hubbard Creek, Paonia, and Coal Creek Canyon, Colorado.

Leff, L. G., J. L. Burch and J. A. McArthur. 1990. Spatial distribution, seston removal, and potential competitive interactions of the bivalves Corbicula fluminea and Elliptio complanata in a coastal plain stream. Freshwater Biology 24(2):409-416.

Within the past 10 years the introduced exotic bivalve, Corbicula fluminea , has spread from the Savannah River through a riverine swamp into a third-order blackwater tributary on the Savannah River Site (SRS). The effects of this invasion on a native bivalve, Elliptio complanata, and on seston concentration in the stream were exsamined. Corbicula fluminea has not yet colonized the entire stream and its distribution limit is coincident with the occurrence of gravel beds. Corbicula fluminea appears to cause localized reduction of seston concentration and may rapidly clear the sediment boundary layer of food. There was no evidence of a negative impact on the distribution of the native bivalve in spite of high measured rates of water clearance by C. fluminea.

Leff, L. G. and A. A. Leff. 2000. The effect of macroinvertebrates on bacterial distributions in freshwater microcosms. Archiv für Hydrobiologie 147(2):225-240.

Bacterial distributions among biofilms and the water column may be altered by a variety of abiotic and biotic factors including feeding and physical activities of macroinvertebrates. The purpose of this study was to examine the effect of macroinvertebrates on abundances and distributions of three species of bacteria that differ in their surface properties and niches. Eight invertebrate genera were examined; functional feeding groups included predators, shredders, filter feeders, and collector-gatherers. The three bacterial species responded to the presence of the macroinvertebrates in generally similar ways, although the species with the most developed ability to attach to surfaces (Burkholderia cepacia) apparently resisted dislodgment by macroinvertebrates. Bacillus thuringiensis, a relatively species-specific insecticidal bacterium, achieved higher abundances on invertebrate exteriors than did B. cepacia and Pseudomonas fluorescens. Orconectes reduced abundances of introduced bacteria on leaves and shifted distributions; a greater percentage of the bacterial populations was found in the sediments of the Orconectes microcosms than in microcosms lacking macroinvertebrates. These alterations were probably the result of consumption of bacteria from epiphytic biofilms and subsequent deposition in feces. Corbicula shifted distributions of two of the bacterial species so that a greater percentage of the populations was in the water column, perhaps as the result of burrowing activity. Both of these invertebrate species are common stream residents and may affect the distribution and persistence of natural and introduced bacteria.

Leiker, T. J., J. E. Madsen, J. R. Deacon and W. T. Foreman. 1994. Methods of analysis of the U.S. Geological Survey National Water Quality Laboratory - determination of chlorinated pesticides in aquatic tissue by capillary-column gas chromatography with electron-capture detection. U.S. Geological Survey, Earth Science Information Center (Denver, Colorado), Open-file Report: 94-710.

A method for the determination of chlorinated organic compounds in aquatic tissue by dual capillary-column gas chromatography with electron-capture detection is described. Whole-body-fish or corbicula tissue is homogenized, Soxhlet extracted, lipid removed by gel permeation chromatography, and fractionated using alumina/silica adsorption chromatography. The extracts are analyzed by dissimilar capillary-column gas chromatography with electron-capture detection. The method reporting limits are 5 micrograms per kilogram (μg/kg) for chlorinated compounds, 50 μg /kg for polychlorinated biphenyls, and 200 μg /kg for toxaphene.

Leistikov, A. 1995. On the composition of species of the Asian clams Corbicula in the lower Rhine Mollusca: Bivalvia: Corbiculidae. Decheniana, Bonn 148:111-114.

Lemaire-Gony, S. and A. Boudou. 1997. Mantle and gill fine structure in the freshwater Asiatic clam, Corbicula fluminea (Müller). Annales de Limnologie 33(3):163-178.

Lenat, D. R. and C. M. Weiss. 1973. Distribution of benthid macroinvertebrates in Lake Wylie, North Carolina   South Carolina. Environmental Sciences and Engineering, University of North Carolina (Chapel Hill), Publication No. 331. 75 pp.

Lenzen, J. D., III. 1999. Mercury bioaccumulation in Corbicula fluminea associated with water hyacinth beds. Master of Science Thesis, California State University at Hayward. viii+76 pp.

Leschke, M. 1914. Zur Molluskenfauna von Java und Celebes. Mitteilungen der Naturforschenden Museum Hamburg 31:205 283.

Lesson, R. P. 1830. Zoologie. IN: Voyage Autour de Monde Execute .. sur la Corvette de S. M. La Coquille, Pendand les Ann'ees 1822 1828, L. J. Duperry. Vol. 2, Part 2. pp. 1 471.

Corbicula nepeanensis is described (p. 428) and figured (pl. 13, fig. 14) from the Nepean River, New Holland [Australia].

Levèque, C. 1967. Mollusques aquatiques de la zone Est du lac Tchad. Bulletin de l'Institut Fondamental d'Afrique Noire, Serie A, Sciences Naturelles 29(4):1494 1533.

Levèque, C. 1972. Mollusques benthiques du Lac Tchad: ecologie, 'etude des peuplements et estimation des biomass. Cahiers de la Office de la Recherche Scientifique et Technique Outre Mer, Serie Hydrobiologie 6(2):3 45.

The study of some ecological factors allowed the identification of the influence of bottom characteristics upon the benthic mollusc populations (including Corbicula africana) in Lake Chad, as well as the existence of a threshold conductivity (600 micro mhos) limiting the presence of molluscs in the northern part of the lake. The rather shallow depth does not appear to have any effect upon the bathymetric distribution of organisms.

After defining a number of biotops in the lake, depending upon the bottom characteristics and geographical position, average population per sample for each biotope was calculated from the data resulting from two expeditions that took place in 1968 and 1970. For each biotop, the stock of the species, generally obey Motomura's abundance distribution law. A number of "nomocenoses" characterized by the number of constituting species, Motomura's constant (identical to a diversity index), and density of populations were defined. Homogeniety and validity of samples were studied using Taylor's law. As a rule, molluscs have a moderate tendency towards aggregation. This tendency is more pronounced for mobile Prosobranchia than for lamellibranchia whose distribution is closer to random.

A study of population's affinities indicates the existence of two main population's areas on the entire lake: biotops of the central area on the one hand, and biotops of the eastern and southern areas on the other hand. The "Grande Barriere" constitutes a junction between the two main areas and represents a geographical as well as biological boundary between the northern and southeastern basins.

Although populations remained relatively stable from 1968 to 1970, one could nevertheless observe the existence of an evolutionary phenomenon in the Bol area where Melania have taken the place of Cleopatra on muddy sediments. This phenomenon is not limited to Bol but was also observed on the part of the eastern archipelago in 1970.

The total number of molluscs was estimated to be 3,640,000,000,000 individuals in 1970 with a biomass of 775,000 tons (alcoholic weight, shells included). Prosobranchia (90% of the total and 83% of biomass), and particularly Bellamya unicolor (45% of biomass) predominate. Biomass is not equally distributed, since 3/4 of them are concentrated in the "Grande Barriere" area and contiguous biotops (45% of the available zone). There is a strong decrease in biomass towards the eastern part and especially towards the northern part of the lake.

Levèque, C. 1973. Dynamique des peuplement biologie et estimation de la production des mollusques benthiques de Lac Tchad. Cahiers de la Office de la Recherche Scientifique et Technique Outre Mer, Serie Hydrobiologie 7(2):117 147.

In accordance with periodical samplings, populations of benthid molluscs in Lake Chad were observed for more than 1 year in three localities (Samia, Bol and baga Kawa). The evolution of the demographic structure (size structure) of the populations during successive samplings has provided the opportunity to study the biology of certain species and, more particularly, reproductive periods and longevity. Bellamya unicolor and Melania reproduce year round, but during the cool season there is a decrease in the birth rate. Corbicula africana have a heavy reproduction during the cool season. The normal one year life span of C. africana can be extended to 3 years or more under certain environmental conditions. After a brief explanation of two methods of production calculation in the case of cohorts (Bojsen Jensen method and method of instantaneous growth rate), one method is suggested which is available as well for populations with complex age structure. This method requires using both the average weight increase of one individual and the demographic structure of populations. With this method, the instantaneous growth rate of the population (G) may be obtained and the instantaneous production estimated with the formula p = G x Biomass. This method was bested before it was applied to benthic mollusc populations from Lake Chad. With the cohorts of C. africana and Bellamya in experimental in situ rearings, the results with this method or with more classical ones are very similar. It is the same for the B. unicolor populations in experimental rearings. The annual production (for dry organic weight and shell weight) of natural populations of Melania, Cleopatra, B. unicolor, and C. africana was estimated in localities where the studies of demography and dynamics were effected. The annual production/biomass (P/B) ratio was calculated. According to the species and localities, t varies between 3 and 6. The use of instantaneous growth rate (G) of the population is discussed. The presence of a relation between G and the average weight of an individual of the population (W) is pointed out for different species. This relation is valid only within certain limits of W. On the other hand, another fairly good relation exists between G and average longevity for different species of aquatic molluscs.

Levèque, C. 1973. Bilaus energetiques des populations naturelles de mollusques du Lac Tchad. Cahiers de la Office de la Recherche Scientifique et Technique Outre Mer, Serie Hydrobiologie 7:151 156.

Levèque, C., J. R. Durand and J. M. Ecoutin. 1977. Relations entre le rapport P/B et la longevitie des organismes. Cahiers de la Office de la Recherche Scientifique et Technique Outre Mer, Serie Hydrobiologie 6(1):17 31.

The life span of Corbicula africana is calculated to be 2 years.

Levèque, C. and M. Gaborit. 1972. Utilization of the factorial analysis of the correspondences for the study of the population of benthic molluscs in Lake Chad. Cahiers de la Office de la Recherche Scientifique et Technique Outre Mer, Serie Hydrobiologie 6(1):47 66.

After a brief account of basic principles necessary for a correct interpretation of the method used, factorial analysis of correspondences was applied to samples taken during two missions in the Bol area (1967 and 1970) and two missions on the whole of Lake Chad (1968 and 1970). Individuality of populations for each type of bottom recorded in the Bol area was shown. In the lake as a whole and for the same geographical zone, the nature of the sediments has some influence on the composition of populations. Populations of the central part of the lake differ fundamentally from the populations of other biotopes of Melania and importance of Bellamya unicolor in their specific profile. On the other hand, Cleopatra are dominant in the eastern part of the lake where Corbicula africana are also of importance. Presence of intermediate populations between the the preceding units, in which the relative importance of Melania and Cleopatra is quite the same, leads to the conclusion that they are two vicariantes species; that is to say that one species can be substituted for the other species under particular conditions. The phenomenon could be observed in 1970 for populations living on the mud in the Bol area, as well as for some biotopes from the eastern zone of the lake. Apart from this evolution, stability is usually observed within a two year period for the average samples of one biotope. There is no specific affinity between the seven species studied.

Lewis, R. B. and J. R. Brice. 1980. A comparison of the past and present mussel fauna of the Kankakee River in Illinois. Natural History Miscellania, Chicago Academy of Science No. 211. 7 pp.

The freshwater mussels of the Kankakee River were surveyed at five locations in Illinois during 1976 and 1978. A total of 20 species were collected in this study compared to 22 species from the same sites in 1909. Actinonaias carinata, the "mucket", was the dominant species observed at most sampling locations during 1976 and 1978. Although the diversity and relative abundance of the freshwater mussels have declined slightly since 1909, the fauna of the lower Kankakee River has not changed drastically during this time period. Corbicula fluminea, which recently entered the Illinois River basin, was also recorded.

Liao, C. M., L. J. Jou and B. C. Chen. 2005. Risk-based approach to appraise valve closure in the clam Corbicula fluminea in response to waterborne metals. Environmental Pollution 135(1):41-52.

A risk-based approach was developed to assess how the valve closure behavior of Asiatic clam Corbicula fluminea responds to waterborne copper (Cu) and cadmium (Cd). We reanalyzed the valve closure response data from published literature to reconstruct the response time-dependent dose-response profiles based on an empirical three-parameter Hill equation model. Probabilistic exposure profiles of measured environmental Cu and Cd concentrations in the western coastal areas of Taiwan were integrated with the reconstructed dose-response relationships at different integration times of response to quantitatively estimate the valve response risk. The risk assessment results implicate exposure to waterborne Cu and Cd may pose no significant risk to clam valve activity in the short-time response periods (e.g., <30 min), yet a relative high risk for valve closure response to waterborne Cu at response times greater than 120 min is alarming. Reconstructed dose-response profiles and EC₅₀-time relationships associated was linked with the fitted daily valve opening/closing rhythm characterized by a three-parameter lognormal function to predict the time-varying bivalve closure rhythm response to waterborne metals. The proposed predictive model that should encourage a risk-management framework was parameterized for discussion of future design of biological monitoring systems.

Liddle, R. A. and K. V. W. Palmer. 1941. The geology and paleontology of the Cuenca   Azogues   Biblian region provinces of Canar and Azuay, Ecuador. Bulletins of American Paleontology 26(100):1 62.

Corbicula cojitamboensis sp. nov. is described (p. 53) and figured (pl. 9, fig. 6) from a four inch seam of highly bituminous limestone 400 m south, 25 degrees west from Cojitambo, a prominent andesite hill in Arroyo Potero, Cuenca vicinity, Ecuador.

Lin, Y. 2004. Distribution of wetland organisms on Jinjiang River mouth and Qunazhou Bay. Journal of Oceanography in Taiwan Strait/Taiwan Haixia 24(2):183-188. [Chinese with English summary]

Since Quanzhou Bay is under the strong influence of the runoff from Jinjiang River mouth, there is a close relationship between the horizontal distribution of wetland organisms and spatial difference in salinity. The wetland organisms are largely divided into outside bay and outer bay species, inner bay low salinity species, and tidal river brackishwater species. Mictyris longicarpus, Arachnoides placenta and Branchiostorna beicheri are only distributed in the sandy sediments outside the bay and in outer bay. Three mangrove species, Spartina alterniflora, fiddler crabs and Periophthalmus cantonensis are dominant species on the mudflats in inner bay. Cyperus malaccensis is the indicator for tidal river freshwater species. Corbicula fluminca is a brackishwater species, but also distributes in the river section with low salinity.

Lin, Y., W. Zhang and Y. Wang. 1980. Bivalves   Mollusca of the Tai hu and its surrounding waters Jiangso Province, China. Acta Zoologica Sinica 26(4):365 369.

Tai Hu, one of the five great lakes of China, is located in the southwestern Yangtse delta. Specimens were collected from the different regions of the lake and its surrounding waters in April and May 1973. Thirty one species belonging to five families (Mytilidae, Unionidae, Solecurtidae, Corbiculidae, and Sphaeriidae) and sixteen genera (Limnoperna, Lamprotula, Acuticosta, Schistodesmus, Hyriopsis, Unio, Lanceolaria, Cuneopsis, Arconaia, Lepidodesma, Cristaria, Solenaia, Anodonta, Novaculina, Corbicula, and Sphaerium) were determined. Seventeen species are endemic to China.

Lindholm, W. A. 1914. Uber Mollusken aus dem Delta Gebiete des Amu Darja. Annales du Muséum Zoologique de la Academie des Sciences USSR 19:340 348.

Lindholm, W. A. 1924. Einige neue mollusken (Pelecypoda und Gastropoda) aus den gewassern Sudost Siberiens. Comptes Rendues Academie des Sciences USSR 28:302 306.

Lindholm, W. A. 1925. Ueber des Vorkommen der Gattung Corbicula im Ussuri Gebiet. Comptes Rendues Academie des Sciences USSR A:29 32.

Corbicula suifuensis sp. nov. is described (p. 29) and figured (pl. 32, figs. 1a, b) from the Suifun River near Razdolnaja, southeastern Siberia).

Lindholm, W. A. 1927. Zur Kenntnis der Corbicula formen (Lamellibrachiata) Sudost Siberiens. Annales du Muséum Zoologique de la Academie des Sciences USSR 28(4):550 554.

Lindholm, W. A. 1930. Molusken aus der Stadlt Alt Buchara und ihrer nachsten Umgebung. Annales du Muséum Zoologique de la Academie des Sciences Leningrad 31:129 134.

Lindholm, W. A. 1933. Eine verschollene Muschel aus Zentralasien. Archiv für Molluskenkunde 65(6):264 268.

Linstow, O. von. 1922. Beitrag zue Geschichte und Verbreitung von Corbicula fluminalis. Archiv für Molluskenkunde 54:113 144.

The paleontology of Corbicula fluminalis in Europe is reviewed. Other data for Australia, North, Central, and South America, and Asia are presented.

Liteanu, E., T. Bandrabur and G. Baltac. 1961. Presence de l'espece Corbicula fluminalis O. F. Müller dans le Holocene du bassin inferieur de Danube. Comunications de la Academie Bueuresti 11:81 87.

Liu, Q., H. Shen, H. Zhou and W. Lu. 1999. Oxygen consumption and ammonia excretory rate of the freshwater clam, Corbicula fluminea. Journal of the Shanghai Fisheries Univiversity/Shanghai Shuichan Daxue Xuebao 8(4):298-303. [Chinese with English summary]

Oxygen consumption rate (OCR) and ammonia excretory rate (AER) of different size, well fed fresh water clam, Corbicula fluminea under various water temperature are measured. The results indicate that both the water temperature and size of the clam have significant effects on OCR and AER. An exponential decrease occurs for both OCR and AER as the clam grows, while OCR and AER increase when water temperature rises within a certain range. Over the upper limit of that range (about 28 degree C), both OCR and AER decrease as water temperature continues to rise. Besides, an evident diurnal rhythm in the respiration of the clam is also found, i.e, OCR of the clam is higher during the day than that at night, and there is no such diurnal rhythm AER.

Llabador, F. 1962. Resultants malacologiques de la Mission Scientifique du T'en'er'e (November 1959 Janvier 1960). IN: Documents Scientifiques Mission Berliet Ténéré Tchad, 1959 1960.

Subfossils of Corbicula fluminalis are reported from Lake Chad. Corbicula lacoini is considered a form of Corbicula fluminalis.

Lo, C. T. 1995. Echinostoma macrorchis: life history, population dynamics of intramolluscan stages, and the first and second intermediate hosts. The Journal of Parasitology 81(4):569-576.

Eggs of Echinostoma macrorchis were laid at the 1-cell stage and took 9 days (26-27^oC) or 6 days (30^oC) to hatch. The following accounts are based on studies undertaken at 24-26^oC. Maximum survival of miracidia was 7 hr. Miracidia reached the ventricle of Gyraulus chinensis 15-20 hr after penetration and transformed into sporocysts. The earliest degeneration of sporocysts occurred 20 days postinfection (DPI), but some survived for 120 days. Mature mother rediac were first seen inside the sporocyst at 7 DPI, then were released to the ventricular cavity and migrated to other anatomical locations of the host. Among the germ balls present in a sporocyst, 1-3 developed concurrently to the mother redia stage. Young daughter rediae first appeared at 15 DPI and mature ones at 19 DPI. Snails of larger size produced more daughter rediae and cercariae than smaller ones. Initial shedding of cercariae from infected snails occurred between 25 and 48 DPI, with a mean of 34 DPI. The cercariae were phototactic and each snail shed a daily average of 34 cercariae. Gyraulus chinensis was proven to be the only snail capable of serving as the first intermediate host. Tadpoles of Rana latouchi and Bufo bufo, 9 species of gastropods, the bivalve Corbicula fluminea, and 1 unidentified planarian species served as experimental second intermediate hosts.

Locard, A. 1883. Malacologie des lac de Tiberiadeem d'Antioche et d'Homs. Archives du Muséum d'Histoire Naturelle de Lyon 3:195 293.

Logan, W. N. 1897. The Upper Cretaceous. University of Kansas Geological Survey 2:202 234.

Lomte, V. S. 1971. Studies on the fresh water mussels of Marathwada Region. Marathwada University Journal of Science, Section B, Biological Sciences 10(3):143 153.

A detailed systematic study of the freshwater mussels of the Marathwada region, Maharashtra State, India, was made. Two families of freshwater mussels, Unionidae and Corbiculidae, are represented. The Unionidae includes three genera (Lamellidens, Parreysia, and Indonaia) while the Corbiculidae is represented only by two species of Corbicula.

Lomte, V. S. and M. L. Jadhav. 1982. Effects of toxic compounds on oxygen consumption in the freshwater bivalve, Corbicula regularis (Prime, 1860). Comparative Physiology and Ecology 7(1):37 38.

Data on the oxygen consumption of Corbicula regularis kept in freshwater of various oxygen contents revealed that consumption decreased immediately as the oxygen supply was lowered. The respiratory rate of C. regularis was much reduced in different concentrations of toxic compounds.

Long, D. P. 1989. Seasonal variation and the influence of thermal effluents on the bioenergetics of the introduced Asian clam, Corbicula fluminea (Müller). Master of Science Thesis, University of Texas at Arlington. xvii+212 pp.

Long, D. P. and R. F. McMahon. 1987. High temperature inhibition of growth and reproduction in a natural field population of Corbicula fluminea. American Society of Zoologists, 1987 Meeting, New Orleans,Louisiana, 27-30 December.

Looby, T. L. 1999. The behavioral monitoring of zebra mussels and Corbicula fluminea under the stress of control measures. Master of Science Thesis, University of Illinois at Urbana-Champaign. vii+150 pp.

Lopez, G. R. and I. J. Holopainen. 1987. Interstitial suspension feeding by Pisidium spp. (Pisidiidae: Bivalvia): A new guild in the lentic benthos? American Malacological Bulletin 5(1):21 30.

Passing reference is made to suspension feeding by Corbicula.

Lorié, J. 1913. Beschrijving van eenige nieuwe grondboringen. VIII. Verhandlingen van de Koninklijke Akademie voor Wetenschappen (Amsterdam) 1913:65 72.

Lott, S. L. 1977. Corbicula manilensis Philippi (Bivalvia: Corbiculidae): some aspects of the functional morphology of the reproductive system, and a preliminary study of shell composition. Master of Science Thesis, University of Arkansas (Fayetteville). ix+49 pp.

Lubinski, K. S. 1987. Community and population characteristics of mussels in the bed at Illinois River Mile 3.0 L. IN: Proceedings of the Workshop on Die Offs of Freshwater Mussels in the United States, R. J. Neves, Ed. U.S. Fish and Wildlife Service, Upper Mississippi River Conservation Committee, and Virginia Polytechnic Institute and State University (Blacksburg). pp. 104 114.

Mussel density, species composition, and height frequencies of commercial species were quantified in the mussel bed at Illinois River Mile 3.0 L to determine if changes have occurred in this river reach during the past twenty years and to provide a data base for interpreting future impacts of barge fleeting, commercial mussel harvesting, die offs, or chemical contamination. Quadrats (0.25m²) were searched in two nearshore zones (WZ1, WZ2) by wading and deeper water (DZ1) using SCUBA methods. Mean densities of live mussels (16 species) were much greater in DZ1 (25.6/ m²) where substrata included gravel and cobbles in a sand/clay matrix, than in WZ1 (1.3/ m²) or WZ2 (1.1/ m²) where a layer of silt between 1 and 5 cm in depth covered the substratum. The maximum density in DZ1 (33.6/ m²) was similar to densities reported for Mississippi River beds. From an estimated bed size of 15,000 m², the total number of live mussels in the bed was calculated to be approximately 360,000. Species area curves indicated that thresholds were reached in WZ1 and WZ2 but not in DZ1. Species composition was similar to that reported for the river reach in 1966. Exceptions included the presence of Corbicula fluminea and Ligumia recta, which had reportedly been eliminated, and the absence of Obovaria olivaria. Live/dead ratios in WZ1, WZ2, and DZ1 were 0.67, 0.56, and 0.69, respectively. Height frequencies of the three major commercial species, Amblema plicata, Megalonaias gigantea, and Quadrula quadrula were similar to those reported in 1966. Increased annual harvests during the 1980's, particularly by diving, have not resulted in measurable changes in either species composition of the community or size structure of commercial species. A recent dead/old dead ratio calculated for 8 quadrats in DZ1 was low (0.04), suggesting that recent summer die offs have not occurred in the Illinois River, as those reported in the Mississippi River.

Luis, E. S., A. H. Balagot, A. C. Villaflor, F. C. Sanchez and E. N. Develles. 1989. Pb, Cd and Hg contents of bivalves collected during the different seasons of the years. Food Chemistry 32(4):239-255.

Levels of lead, cadmium and mercury were determined in Ostrea malabonensis, Perna viridis, Arca spp and Corbicula manilensis , and the seawater where the saltwater bivalves were harvested. The heavy metals were determined by atomic absorption spectroscopy. The average concentration of Pb, Cd and Hg in the bivalves ranged from 0 multiplied by 64 to 2 multiplied by 24 ppm, 0 multiplied by 06 to 0 multiplied by 66 ppm and 0 multiplied by 62 to 11 multiplied by 68 ppb, respectively. The variations due to sample and season of the Pb and Cd contents in the bivalves were found insignificant. The saltwater bivalves exhibited low bio-accumulation factors for the three metals studied. Overall, the findings demonstrated that the four bivalves are safe for human consumption and that the ecosystems where they were harvested do not pose any hazard to man or to marine life.

Luoma, S. N., P. V. Cascos and R. Dagovitz. 1984. Trace Metals in San Francisco Bay, California, near the Proposed San Luis Drain Discharge Site: A Preliminary Report. U.S.G.S. Water Resources Division (Sacramento, California), U.S.G.S. Water Resources Investigatons Report 84-4170. 35 pp.

A 5-month partial study (February to July 1983) was completed in Suisun Bay, a shallow embayment of San Francisco Bay, California, to determine characteristic heavy metal concentrations present in sediments and organisms (Corbicula clams) prior to possible discharge of San Luis Drain irrigation tile return water. Preliminary results show sediments are typical of other San Francisco Bay study sites, ranging from coarse sands to fine silt-clays. The sediments are enriched in manganese and low in organic carbon; iron is moderately enriched, with acid-extractable iron concentrations of 162-3,521 μg/g. Sediment concentrations of silver, zinc, lead, and cadmium measured between April and July are reported. Previous area studies have shown increased concentrations during autumn and winter, a period not covered in this data set. Due to insufficient data, interpretations are incomplete. Clam-tissue burdens for silver and zinc are similar to those found in Corbicula from pristine areas. Lead concentrations are typically below the 2 μg/g detection level. Corbicula do show indications of more tissue enrichment for cadmium and copper at estuarine stations than at riverine stations.

Luoma, S. N., R. Dagovitz and E. Axtmann. 1990. Temporally intensive study of trace metals in sediments and bivalves from a large river-estuarine system: Suisun Bay/Delta in San Francisco. Science of the Total Environment 97/98:685-712.

Distributions in time and space of Ag, Cd, Cr, Cu, Pb and Zn were determined in fine-grained sediments and in the filter-feeding bivalve Corbicula sp. of Suisun Bay/delta at the mouth of the Sacramento and San Joaquin Rivers in North San Francisco Bay. Samples were collected from seven stations at near-monthly intervals for 3 years. Aggregated data showed little chronic contamination with Ag, Zn and Pb in the river and estuary. Substantial chronic contamination with Cd, Cu and Cr in Suisun Bay/delta occurred, especially in Corbicula, compared with the lower San Joaquin River. Salinity appeared to have secondary effects, if any, on metal concentrations in sediments and metal bioavailability to bivalves. Space/time distributions of Cr were controlled by releases from a local industry. Analyses of time series suggested substantial inputs of Cu might originate from the Sacramento River during high inflows to the Bay, and Cd contamination had both riverine and local sources. Concentrations of metals in sediments correlated with concentrations in Corbicula only in annually or 3-year aggregated data. Condition index for Corbicula was reduced where metal contamination was most severe. The biological availability of Cu and Cd to benthos was greater in Suisun Bay than in many other estuaries. Thus small inputs into this system could have greater impacts than might occur elsewhere; and organisms were generally more sensitive indicators of enrichment than sediments in this system.

Lupton, C. T. 1916. Geology and coal resources of Castle Valley, in Carbon, Emery and Sevier counties, Utah. Bulletin of the U.S. Geological Survey No. 628:1 88.

Corbicula sp. (related to Corbicula durkeei [Meek, 1869]) is reported from the ferron sandstone member of the Mancos Cretaceous, Castle Valley, Utah.

Lutz, R. A., M. J. Kennish, A. S. Pooley and L. W. Fritz. 1994. Calcium carbonate dissolution rates in hydrothermal vent fields of the Guaymas Basin. Journal of Marine Research 52(5):969-982.

Analysis of bivalve shell fragments that were embedded in epoxy blocks, mounted on titanium stakes, and deployed by DSRV Alvin at 5 sites in the Southern Trough of the Guaymas Basin (27^o00'N, 111^o24.55'W; depth 2012 m) indicates significant variation of calcium carbonate dissolution in in situ exposures of more than 900 days. Arrays of shell fragments of six bivalve species (i.e., Bathymodiolus thermophilus, Calyptogena magnifica, Calyptogena sp., Corbicula fluminea, Crassostrea virginica and Mytilus edulis) were positioned -17 cm, -7 cm and -2.5 cm below the sediment-water interface and 2.5 cm, 7 cm and 17 cm above the sediment-water interface in hydrothermal vent fields of the basin. Maximum dissolution rates for both calcite (mean = 86 μm/yr) and aragonite (mean = 312 μm/yr) were found in epoxy blocks located at the deepest point sampled in the sediment column (depth = 17 cm). Minimum dissolution rates of calcite and aragonite were found 7 cm (mean = 26 μm/yr) and 2.5 cm (mean = 96 μm/yr) above the sediment-water interface, respectively. Intermediate rates of dissolution were recorded 17 cm above the sediment-water interface (mean = 40 μm/yr for calcite and 126/yr for aragonite). Mean rates of aragonite dissolution ranged from 59 μm/yr (site 5; clam area) to 227 μm/yr (site 3; clam area), and those of calcite dissolution ranged from 13 μm/yr (site 3; clam area) to 94 μm/yr (site 4; bacterial mat area). Dissolution rates were consistently highest in the bacterial mate area μm/yr (site 4; mean = 94 μm/yr for calcite and 223 μm/yr for aragonite). Rates of calcium carbonate dissolution reported here for hydrothermal vent fields of the Guaymas Basin compare favorably with those of Rose Garden (Galapagos Rift) and 21^oN (East Pacific Rise) hydrothermal vent sites. These results have important implications for assessing biological rate processes in deep-sea hydrothermal vent environments.

Luz, K. D. G. 2002. Alterations in the Pterodoras granulosus (Valenciennes, 1833) (Osteichthyes, Doradidae) diet due to the abundance variation of a bivalve invader species in the Itaipu Reservoir, Brazil. Acta Scientiarum 24(2):427-432.

The effect of the population fluctuations of the introduced bivalve Corbicula fluminea on the diet of the freshwater fish Pterodoras granulosus, was studied. It was observed that during the years with higher population levels of the bivalve, the fish diet was based mainly on this species, while during the years of lower population the fish fed mainly on algae and vascular plants.

Lynde, S. R., D. S. Cherry, A. L. Buikema and J. L. Lauth. 1993. Comparison on invertebrate impairment and microbial colonization of leaves in river sediment exposed to copper. 14th Annual Meeting, Society of Environmental Toxicology and Chemistry- Ecological Risk Assessment: Lessons Learned? Houston. Texas, 14-18 November. Abstract Book.

It has been demonstrated that sediments act as both a source and sink for contaminants in the environment. The need for reliable, reproducible test methods and organisms is apparent. Four invertebrates (Daphnia magna, Chironomus riparius, Corbicula fluminea, and Hyalella azteca) were exposed to sediments dosed with copper and their responses compared to determine which organism is best suited for bioassays, using Clinch River sediment. Also examined was the colonization of microbes on leaf material. Sediment was collected from the Clinch River at Cliffield, Virginia, sieved on site and brought back to the laboratory for dosing. Sediments were dosed with copper (as CuCI₂.2H₂O) with concentrations ranging from 30 to 3000 mg Cull sediment. Water column and sediment concentrations were determined by atomic absorption spectrophotometry. Ten-day chronic endpoints for D. magna and C. riparius included survival and reproduction /growth. Survival, growth and tissue water concentration of the Asian clam (Corbicula fluminea) was tested using 24-48 hour old and less than or equal to 10 mm juveniles. Corbicula tissue water concentrations did not show significant increases as a response to copper concentration. Survival and growth in the amphipod (Hyalella azteca) was examined in 28-day bioassays. Leaf disks placed on sediments in 10-day bioassays were examined under fluorescent microscopy for microbial colonization. These data show impairment in chronic endpoints at concentrations higher than 300 mg Cu/L sediment.