-- P -- Paepe, R., C. Baeteman, R. Mortier and R. VanHoorne. 1981. The marine Pleistocene sediments in the Flandrian area. IN

A review of the Pleistocene marine stratigraphy of the Belgian coastal plain is given, including a critical discussion of the formerly used nomenclature. A stratigraphical revision of formations introduced in the first edition of the legend of the Geological Map of Belgium is made.

Hence, the Oostende Formation (type locality Oostende) stands for marine deposits of Eemian age, the Herzeele Formation (type locality Herzeele in France) stands for marine deposits of both Holsteinian and `Cromerian' age. In the Flemish Valley as well as in the eastern part of the coastal plain both formations are found to exist generally superposed. Here the Zeebrugge Member of the Herzeele Formation is introduced to indicate marine deposits with Corbicula fluminalis and Tapes senescens var. eemiensis. Neither fossils are therefore considered as solely belonging to the Eemian stage.

Paepe, R., J. Somme, N. Cunat and C. Baeteman. 1976. Flandrian, a formation or just a name. Newsletter on Stratigraphy 5(1):18 30. [English with English and Dutch summaries]

The name Flandrian is now used to indicate deposits of the Flandrian transgression or of the Holocene as a whole, in particular Anglo Saxon literature. As most geological connotations, Flandrian has changed significance and chronostratigraphic age since it was created in 1885 by Rutot and van den Broeck.

At that time, Flandrian was a Pleistocene "assise" which occurred at the end of long series of Quarternary and tertiary stages. Therefore, it completed and still completes the geological tradition of the Cenozoic sequence. Of particular importance in the elucidation of these strata are sand beds containing Corbicula fluminalis.

Paetel, F. 1890. Catalog der Conchylien Sammlung von F. Paetel. Lief. 11 18. Abth. II, Land  und S:usswasser Gastropoden, pp. 161 505; 3, Acephalen und die Brachiopoden. 256 pp.

Corbicula spp. are discussed on pages 100 104.

Paetel, F. 1890. Die Bisher Veroffenttlichten Familien  und Gattunsnamen der Mollusken. (Berlin). 229 pp.

Page, T. L., D. A. Neitzel, M. A. Simmons and P. F. Hayes. 1983. Biofouling of Power Plant Service Systems by Corbicula. U.S. Department of Energy, Batelle Pacific Northwest Labs (Richland, Washington). 20 pp. [NTIS No. DE830116086]

See below

Page, T. L., D. A. Neitzel, M. A. Simmons and P. F. Hayes. 1986. Biofouling of power plant service systems by Corbicula. IN: Proceedings of the Second International Corbicula Symposium, J. C. Britton, Ed. American Malacological Bulletin Special Edition No. 2. pp. 41 45.

Pallary, P. 1901. Sur les mollusques fossiles, terrestres et saum`atres de l'Algerie. Mémoirs de la Société Géologique de France, Paleontologie 9:1 213.

Pallary, P. 1903. Mollusques recueillis par Dr. Innes Bey dans le Haut Nil. Bulletin de l'Institute Egyptien 3:87 98.

Pallary, P. 1909. Catalogue de la faune malacologique de l'Egypte. Bulletin de l'Institute Egyptien 6:1 92.

Other species of Corbicula proposed by Bourguignat in his collections are reported as nomina nuda: Corbicula aboula (Alexandria); Corbicula alexandrina (Mahmoudieh); Corbicula ampla (Suez); Corbicula aniara (Alexandria); Corbicula aremna (Alexandria); Corbicula aresca (Alexandria); Corbicula asemna; Corbicula bubastica (Zagazig); Corbicula bythydea (freshwater canals of Suez); Corbicula chlora (Mahmoudieh Canal); Corbicula cloti (Suez); Corbicula didieri (Canal Mustapha, Alexandria); Corbicula didieriana; Corbicula encya (Bassin du jardin Kbedivial d'Ismalia); Corbicula eucistaera; Corbicula innesi (Nile River at Cairo); Corbicula insignata (Suez); Corbicula khedivalis (Mahmoudieh Canal); Corbicula lacunosa (Alexandria); Corbicula laurenti (Suez); Corbicula linanti (Medinet el Fayoum); Corbicula mahmoudiana (Mahmoudieh); Corbicula micra; Corbicula minutalis (Suez); Corbicula miranda (Suez); Corbicula nea (Medinet el Fayoum); Corbicula nilotica (Nile River); Corbicula nitida (Nile River); Corbicula nivea (Suez); Corbicula oncalla (Canals of Alexandria); Corbicula parthenina (Alexandria); Corbicula petrettinii (Marais de Ramleh); Corbicula pharaonum (Medinet el Fayoum); Corbicula plagista (freshwater canals of Suez); Corbicula plagista (freshwater canals of Suez); Corbicula platea (Suez); Corbicula popularis (Suez); Corbicula progastera (Mahmoudieh Canal); Corbicula rypara (Canal de Ras el Ouady); Corbicula schweinfurthi (Bassin des Jardins de Ramleh); Corbicula singularis (Jardins de Ramleh); Corbicula specialis (Mahmoudieh Canal); Corbicula turgida (Medinet el Fayoum); and Corbicula thaumasia (Suez).

Pallary, P. 1921. Faune Malacologique du Grand Atlas. Journal de Conchyliologie 66:185 217.

Corbicula artini alexandrie ssp. nov is described from Alexandria, Egypt.

Pallary, P. 1924. Supplement a la faune malacologique que terrestres et fluviatile de l'Egypte. Bulletin de l'Institute Egyptien 7(1):1 61.

Paller, M. H., C. H. Jagoe, H. Bennett, H. A. Brant and J. A. Bowers. 2004. Influence of methylmercury from tributary streams on mercury levels in Savannah River Asiatic clams. Science of the Total Environment 325(1-3,):209-219.

Average methylmercury levels in five Savannah River tributary streams, sampled 11 times over 2 years (0.170 ng/l), were nearly twice as high as in the Savannah River (0.085 ng/l). Total mercury levels in the tributaries (2.98 ng/l) did not differ significantly from the river (2.59 ng/l). All of the tributaries drained extensive wetlands that would be expected to support comparatively high rates of methylation. Mercury concentrations in Asiatic clams (Corbicula fluminea) collected from the discharge plumes of Savannah River tributaries (average of 0.044 μg/g wet weight) were significantly (P<0.001) higher than in Asiatic clams collected from the Savannah River upstream from the tributary mouths (average of 0.017 μg/g wet weight). These results indicate that streams draining wetlands into coastal plain rivers can create localized areas of elevated methylmercury with resulting increases in the mercury levels of river biota.

Palmer, K. V. W. 1945. Fossil fresh water Mollusca from the state of Monagas, Venezuela. Bulletins of American Paleontology 31(118):1 34.

Pandya, A. P. and N. R. Mehta. 1982. Freshwater snails on irrigated area of Surat District, Gujarat, India. Journal of the Zoological Society of India 34(1 2):118 120.

Paravicini, E. M. M. 1922. Over shadelijke en nuttige weekdieren van tropisch Azie. Overgedrulet uit het Tijschrift Teysmannia 1(2):24 28.

Corbicula ducalis and Corbicula javanica are discussed from tropical Asia.

Paravicini, E. M. M. 1935. Beitrage zur Kenntnis der land  und Süsswasser Mollusken von Sumatra. Archiv für Molluskenkunde 67(2):59 63.

Paravicini, E. M. M. 1935. Beitrage zur Kenntnis der Molluskenfauna von Java. Archiv für Molluskenkunde 67:169 175.

Park, G.-M. and E.-Y. Chung. 2003. Molecular phylogenetics of five Corbicula species determined by partial 28S ribosomal RNA gene sequences. Journal of Shellfish Research 22(2):481-485.

Partial 28S ribosomal RNA (rRNA) gene sequences of five species (C. fluminea, C. papyracea, and C. leana from Korea, C. japonica from Japan, C. largillierti from China) in the genus Corbicula were investigated for their genetic divergence. Neighbor-joining analysis on the alignment of 412 base pairs of C. fluminea, C. largillerti, C. papyracea, C. leana and C. japonica (with Polymesoda maritima, P. caroliniana and Sphaerium corneum chosen as an outgroup) provides a robust molecular phylogeny for the genus; (C. japonica, C. papyracea, C. largillierti, C. leana, C. fluminea, P. maritime, P. caroliniana, and S. corneum). The results of this study provide potential use of 28S rRNA gene sequence for phylogenies in the family Corbiculidae.

Park, G.-M. and E.-Y. Chung. 2004. Histological studies on hermaphroditism, gametogenesis and cyclic changes in the structures of marsupial gills of the introduced Asiatic clam, Corbicula fluminea, and the Korean clam, Corbicula leana. Journal of Shellfish Research 23(1):179-184.

The marsh clams, Corbicula fluminea and Corbicula leana, are functional hermaphrodites. They usually appear to be surrounded by numerous spermatozoa in the hermaphroditic follicles. In both species, the follicular ganglia (consisting of the neuronal fiber and neuronal soma-like cells at its periphery) are associated with neurosecretion and the differentiation of complex innervated nerve structures during spermatogenesis and are widely distributed in the follicles in the ripe and spawning stage. Corbicula fluminea and C. leana have two pairs of gills, with the inner-demibranchs acting mainly as marsupia. The non-marsupial demibranchs are not separated, but in the marsupial demibranchs, cyclic changes in the structures of the inner-demibranchs of the gills appear, with the depletion of ripe eggs during incubatory periods and the production of mature and ripe eggs during nonincubatory periods. The reproduction of triploid C. fluminea and C. leana may occur by parthenogenesis without self-fertilization (or cross-fertilization) by eggs and sperm. The DNA contents of the somatic (gill) and gamete (spermatozoa) cells of C. fluminea are the same. Because reproduction is parthenogenetic, numerous spermatozoa may participate in the activation of the mature eggs and egg cleavage, as a stimulus only for parthenogenesis in the same hermaphroditic follicle or the gonophore.

Park, G.-M., T.-S. Yong, K.-I. Im and E.-Y. Chung. 2000. Karyotypes of three species of Corbicula (Bivalvia: Veneroida) in Korea. Journal of Shellfish Research 19(2):979-982.

The chromosome numbers of three species of Korean Corbicula are investigated here: C. fluminea 54, C. papyracea 54, and C. colorata 38. In C. fluminea and C. papyracea, the mitotic chromosomes from 18 sets of three chromosomes each showed that these two species are triploids. In C. colorata, the mitotic chromosomes from 19 groups with two chromosomes each indicated that it is a diploid. C. fluminea and C. papyracea have one set of metacentric chromosomes, five sets of submetacentrics chromosomes, and 12 sets of subtelocentric chromosomes. C. colorata has been considered a subspecies of C. papyracea, but its karyotype indicates that it is a distinct species since it is undoubtedly reproductively isolated from the other two Korean species studied.

Park, J. K., B. L. Choe and K. S. Eom. 2004. Two mitochondrial lineages in Korean freshwater Corbicula (Corbiculidae: bivalvia). Molecules and Cells 17(3):410-414.

The Korean freshwater Corbicula was surveyed genetically by sequencing 614-bp homologous fragment of mitochondrial cytochrome oxidase I subunit. Among a total of 127 individuals collected from 12 Korean freshwater localities we found only two COI haplotypes and these differed by a total of 9 base substitutions. Although the sequence divergence between the two haplotypes is moderate (p = 1.47%), placing the two mitotypic sequences in the context of Asian mtDNA phylogeny reveals that Korean freshwater Corbicula is comprised of two independent freshwater mitochondrial lineages. These results are in serious disagreement with the long-standing conclusions of earlier conchology-based taxonomic work on Korean Corbicula in which a number of species names (a minimum of 10 nominal species) have been used. This indicates that morphological characteristics alone are poor criteria for species-level identification in this group. In addition, our COI dataset shows that there is an extremely low level of genetic variation in Korean freshwater populations, suggesting that these populations have passed through a severe population bottleneck that greatly reduced their genetic variability. The data also provide new information on the biogeographic distribution of Korean freshwater Corbicula. When haplotypic frequencies were compared, it was evident that the two Korean freshwater mitochondrial lineages have achieved very different distribution ranges: the predominant lineage (FWKR1) is widely distributed in Korean freshwater systems, whereas the minor lineage (FWKR2) is restricted to a relatively narrow range.

Park, J.-K. and W. Kim. 2003. Two Corbicula (Corbiculidae: Bivalvia) mitochondrial lineages are widely distributed in Asian freshwater environment. Molecular Phylogenetics and Evolution 29(3):529-539.

The biogeography of Asian Corbicula was investigated using mitochondrial gene sequence variation for Corbicula members sampled from 24 localities of eight Asian regions. A total of 210 individuals were genetically characterized by examining sequence variations of a 614 bp fragment of the mitochondrial cytochrome oxidase I (COI) gene. Phylogenetic analyses of the COI dataset revealed that Corbicula members are subdivided into two well-supported clades: estuarine and freshwater. A robust dichotomy between the Japanese/Korean (Corbicula japonica) and Chinese (Corbicula fluminalis) estuarine forms was evident, suggesting that these two regional populations represent a deep phylogeographic split. Our mitochondrial gene tree showed that among the freshwater members, two Corbicula mitochondrial lineages are the most common, having attained extensive geographic distribution in the Asian freshwater environment. While the present study provides significant biogeographic information on Asian Corbicula, a comprehensive phylogenetic study by cross-referencing the mitochondrial-based Corbicula phylogeny with nuclear gene data is required to fully understand the evolutionary origin(s) of triploidy/clonality in this genus.

Park, J. K., J. S. Lee and W. Kim. 2002. A single mitochondrial lineage is shared by morphologically and allozymatically distinct freshwater Corbicula clones. Molecules and Cells 14(2):318-322.

Despite that the exotic invasion and rapid range expansion of Asian freshwater Corbicula into new environments have been of intensive research topic in freshwater ecology, the genetic structures of freshwater Corbicula in its native range remain poorly understood. In this study, the genetic structures of two Korean freshwater Corbicula clonal lineages were characterized by cross-referencing the nuclear genomic structures with mtDNA sequence analysis. In spite of substantial genetic differences (Nei's D = 0.363-0.372) and a pronounced level of fixed allelic distinctions (in six of 20 allozyme loci) between Corbicula lineages, no lineage-specific mtDNA differentiation was observed. The evident disjunction between mtDNA sequences and nuclear genomes is a compelling evidence for the existence of interspecific nuclear hybrid genome structures, comprising different combinations of paternal and maternal contributions. This unusual novel finding is the first case demonstrating that morphologically and allozymatically distinct, yet mitochondrially identical clonal lineages exist in the genus Corbicula. However, we could not find the ancestral species for these two clonal lineages in the present study, and the answer for this question must wait until the genetic structure of Asian Corbicula taxa is fully characterized.

Park, S. Y., S. Y. Kim and D. H. Cho. 1974. NAD dependent malate dehydrogenase isozymes of ten species of Bivalvia. Korean Journal of Zoology 17(4):163 166. [Korean with English summary]

Malate dehydrogenase (EC1.1..1.37) of 10 bivalves (including Corbicula fluminea, Corbicula producta, and Corbicula felnouilliana) consist of 1 or 2 isozymes that are species specific. The electrophoretic characters of the enzyme is available for identification of the 10 bivalve species.

Parmalee, P. W. 1965. The Asiatic clam (Corbicula) in Illinois. Transactions of the Illinois Academy of Science 58(1):38 45.

Specimens of Corbicula were obtained at 18 localities in the Ohio River, lower Wabash River, and Mississippi River bordering southern and eastern Illinois. The clam has become established throughout the low Ohio River and has ascended the Wabash River as far as White County, Illinois. No specimens were found in the Mississippi River above Cairo. Rapid dispersion and population growth of this introduced mollusc in Illinois have occurred within the past four or five years.

Parmalee, P. W. 1970. Freshwater mussels of Illinois. Illinois State Museum Popular Science Series 8:1 108.

Parmalee, P. W. and W. E. Klippel. 1984. The naiad fauna of the Tellico River, Monroe County, Tennessee. American Malacological Bulletin 3(1):41 44.

The Tellico River, approximately 90 km in length, is a major tributary of the Little Tennessee River in east Tennessee and supports a freshwater mussel population comprised of 15 species and Corbicula fluminea. Corbicula fluminea shells were noted in piles along the banks and were eaten by muskrats. The shells of C. fluminea far outnumbered those of endemic species wherever both were encountered.

Parmalee, P. W. and R. R. Polhemus. 2004. Prehistoric and pre-impoundment populations of freshwater mussels (Bivalvia: Unionidae) in the South Fork Holston River, Tennessee. Southeastern Naturalist 3(2):231-240.

The South Fork Holston River is one of three major tributaries of the Holston River, originating in Smyth County in southwestern Virginia and flowing southwesterly and then northwesterly to where it enters the Holston River at Kingsport, Tennessee. Three dams constructed in the 1950s, Fort Patrick Henry, Boone and South Holston, impounded the entire stretch of river flowing through Tennessee. Identification of shell recovered from two prehistoric aboriginal sites, Eastman Rockshelter (40SL34) and Site 40SL330, and from two collections of relic shells plus species recorded from four localities by Ortmann (1918), provides evidence for a diverse and abundant naiad fauna prior to impoundment. Thirty-five species of mussels historically inhabited stretches of the South Fork Holston River flowing through Tennessee; all have been extirpated. Populations of Actinonaias pectorosa, Lampsilis fasciola, Fusconaia subrotunda, and Ptychobranchus subtentum appear to have been four of the most abundant naiads inhabiting the river. In addition to the Asian clam, Corbicula fluminea, the giant floater (Pyganodon grandis) and paper pondshell (Utterbackia imbecillis) are invader species now common throughout the reservoirs.

Parodiz, J. J. 1969. The Tertiary non marine Mollusca of South America. Annals of the Carnegie Museum 40:1 242. [Spanish summary]

The fossil Neocorbicula stelzneri sp. nov. is described from the Miocene of Santa Maria Valley, Argentina, on p. 93. The species is also figured.

Parodiz, J. J. and L. Hennings. 1965. The Neocorbicula (Mollusca, Pelecypoda) of the Parana Uruguay basin, South America. Annals of the Carnegie Museum 38(3):69 96.

The Corbiculidae of eastern South America, formerly placed in the genus Corbicula, are here grouped in Neocorbicula Fischer, 1887, with Tellina limosa Maton as the type. The presence of a pallial sinus characterizes both New World genera, Polymesoda and Neocorbicula, but in the former the shells are heavier and the lateral teeth are not crenulated. About 40 nominal species were described before the variability and genetic relationship of the forms were understood. Of these, only two represent fundamental specific types: Neocorbicula limosa (Maton) and Neocorbicula paranensis (d'Orbigny). The species of Neocorbicula are hermaphroditic, apparently self fertilizing, and sexually mature at an early age. They incubate their embryos in the marsupial gill for a long time. All adults, and even half grown individuals observed, were gravid. Pure males were not found. On this account the populations are broken into very small and closely settled aggregations on individuals of direct line of descent, equivalent to microdemes or colonies. Each colony shows minimum variation among the individuals in the colony, but accentuates differences to other colonies, forming clones, not clines. While distant allopatric clones may repeat or duplicate certain individual characteristics, other very close sympatric clones differ greatly. The size and structure of the populations, and the embryological characteristics, suggest genetic drift. Extensive collecting along the Parana and Uruguay rivers was done by the senior author from March to May 1961. Neotypes for Neocorbicula limosa and Neocorbicula paranensis were selected and have been deposited in the Carnegie Museum collection. Fossil species from the Paleogene of Patagonia are referred, after studies of types, to the genus Neocorbicula.

Patte, E. 1973. Observations concernant les terrasses de l'Oise et de l'Aisne. Annales des Sciences Universite de Bensancon Geologie 21:81 82.

The Oise and the Aisne have numerous common characteristics. They both have worn Acheulean and artifacts of Levalloisian technique, rolled or unrolled, in the Low Terrace. Both homiotherms are poikilotherms occur at the lowest level. The Oise, at the very low level of Moru near Pont Ste. Maxence, carries remains of Elephas antiquus and hippopotamus, with intense solifluxion. Elephas primigenius is found at the level of Sempigny, and red deer (but no reindeer), with rolled Acheulan and flint blades. The Aisne has a distinct 15 17 m terrace below Soissons, with numerous Corbicula fluminalis. Elephas antiquus was found in the low terrace of Buissonet in the Compiegne Forest.

Pavlovic M. N. 1948. O slojevima sa Carbicula (sic) fluminalis Müll. na Ovcem de l'Ovce Polju (Makedonija) [Note sur les conches a C. fluminalis de l'Ovce Polje (Macedoine)]. Bulletin du Muséum d'Histoire Naturelle de Pays Serbe 1:87 92. [Serbian with French summary]

Corbicula fluminalis is reported from Pleistocene beds of Macedonia.

Pawlow, M. 1906. Etudes sur l'histoire pal'eontologique des ongulés. IX. Mémoires Academie St. Pétersburg VIII série, 20:6

Payne, B. S. and A. C. Miller. 1997. Spatial distribution of mussels at a bed in the lower Ohio River near Olmsted, Illinois. U.S. Army Corps of Engineers Waterways Experiment Station (Vicksburg, Mississippi), Technical Report EL-97-3. viii+51 pp.

Payne, B. S., A. C. Miller, P. D. Hartfield and R. F. McMahon. 1989. Variation in size demography of lotic populations of Corbicula fluminea (Müller). The Nautilus 103(2):78-82.

Patterns of size demography among 14 lotic populations of the Asiatic clam, Corbicula fluminea, in the state of Mississippi were compared based on samples collected between May 24 and June 22, 1984. Individuals greater than 20 mm in shell length (SL) and greater than 1 year old comprised a substantial fraction of only six populations. These populations had distinct multiple cohorts. Four of the six populations occurred among longer-lived native unionids, suggesting that streambed stability is crucial to the establishment of lotic populations of C. fluminea with complex size (and age) structure.

Payne, B. S., J. Lei A. C. Miller and E. D. Hubertz. 1995. Adaptive variation in palp and gill size of the zebra mussel (Dreissena polymorpha) and Asian clam (Corbicula fluminea). Canadian Journal Of Fisheries And Aquatic Sciences/Journal Canadien Des Sciences Halieutiques Et Aquatiques 52(5):1130-1134.

Significant interpopulation differences occur in palp to gill area ratios of two nonindigenous species of freshwater bivalves in North America, Dreissena polymorpha and Corbicula fluminea. Larger palps (both species) and smaller gills (C. fluminea) occur in individuals from habitats characterized by a relatively high suspended solids concentration. The extremely brief evolutionary history of both species in North America is strong evidence that these differences in palp to gill area ratios are ecophenotypic.

Payne, B. S., A. C. Miller and J. Lei. 1995. Palp to gill area ratio of bivalves: A sensitive indicator of elevated suspended solids. Regulated Rivers: Research and Management 11(2):193-200.

Area measurements were made of the gills and labial palps of several freshwater bivalve species from sites with distinctly different suspended solids concentrations. Without exception, the palp to gill area ratio (PA:GA) was markedly higher for populations from sites with high versus low suspended solids concentrations. The average PA:GA (expressed as a percentage) ranged from 9.3 to 11.5 for bivalves from high suspended solids concentration sites and from 2.5 to 4.8 for bivalves from low suspended solids concentration sites. Such interpopulation differences were observed for two introduced species, Dreissena polymorpha and Corbicula fluminea, despite extremely brief residence times in an evolutionary sense. At any particular location, different species of native unionids had similar PA:GA. These results suggest that PA:GA is a sensitive biological indicator of suspended solids concentration, with interpopulation differences probably reflecting ecophenotypic rather than genetic variation.

Payne, H. A. 1985. Development of a Method for Poliovirus Detection in Freshwater Clams. Master's Thesis, University of Arizona. 41 pp.

Although methods for virus detection in marine molluscs have been previously developed, methods for the concentration and detection of viruses in freshwater clam homogenates have not been studied. Homogenates from the freshwater clam, Corbicula fluminea, were seeded with poliovirus type 1. Four pH levels were tested to determine the optimal condition for adsorption of virus to homogenate. At a pH of 4.5 and an electrical conductivity of <1500 ppm, an average of 99.94% adsorption of the virus to the clam homogenate occurred. Elution of virus from the homogenate was achieved at pH 9.0 and a conductivity of >8000 ppm. Eluent containing beef extract and sodium chloride provided 30% greater recovery than the sodium chloride eluent alone. High salt concentration was necessary for maximum virus recovery. Organic flocculation was used as a method for concentration of virus from the eluted homogenate. Optimal conditions for flocculation included a conductivity of <4000 ppm and beef extract as the resuspending medium.

Peale, A. C. 1877. Report on the geology of the Green River district. U.S. Geological and Geographic Survey of the Territories (Hayden Survey), 11th Annual Report. pp. 511 644.

Peale, A. C. 1912. On the stratigraphic position and age of the Judith River formation. Journal of Geology 20:530 549.

Pereira, D., I. L. Veitenheimer-Mendes, M. C. D. Mansur and M. C. P. da Silva. 2000. Malacofauna limnica do sistema de irrigacao da microbacia do arroio capivara, triunfo, RS, Brasil. Biociencias 8(1):137-157. [Portuguese]

The limnic mollusc fauna qualitative inventory of the Capivara Stream Microbasin irrigation system in the county of Triunfo, Rio Grande do Sul, Brazil, was performed from July 1988 to January 1999. It consisted of twelve Gastropoda species (two Ampullariidae, one Hydrobiidae, one Physidae, one Lymnaeidae, four Planorbidae, one Succineidae and two Ancylidae) and nineteen Bivalvia species (seven Hyriidae, six Mycetopodidae, five Sphaeriidae and one exotic Corbiculidae: Corbicula fluminea (Müller, 1774)). The distinct environments of the area, the environmental preferences, and the freshwater mollusc association with several aquatic macrophyte species are described and discussed.

Pereira, W. E., J. L. Domagalski, F. D. Hostettler, L. R. Brown and J. B. Rapp. 1996. Occurrence and accumulation of pesticides and organic contaminants in river sediment, water and clam tissues from the San Joaquin River and tributaries, California. Environmental Toxicology and Chemistry 15(2):172-180.

A study was conducted in 1992 to assess the effects of anthropogenic activities and land use on the water quality of the San Joaquin River and its major tributaries. This study focused on pesticides and organic contaminants, looking at distributions of contaminants in water, bed and suspended sediment, and the bivalve Corbicula fluminea. Results indicated that this river system is affected by agricultural practices and urban runoff. Sediments from Dry Creek contained elevated concentrations of polycyclic aromatic hydrocarbons (PAHs), possibly derived from urban runoff from the city of Modesto; suspended sediments contained elevated amounts of chlordane. Trace levels of triazine herbicides atrazine and simazine were present in water at most sites. Sediments, water, and bivalves from Orestimba Creek, a westside tributary draining agricultural areas, contained the greatest levels of DDT (1,1,1-trichloro-2,2-bis[p-chlorophenyl]ethane), and its degradates DDD (1,1-dichloro-2,2-bis[p-chlorophenyl]ethane), and DDE (1,1-dichloro-2,2-bis[p-chlorophenyl]ethylene). Sediment adsorption coefficients (K_oc), and bioconcentration factors (BCF) in Corbicula of DDT, DDD, and DDE at Orestimba Creek were greater than predicted values. Streams of the western San Joaquin Valley can potentially transport significant amounts of chlorinated pesticides to the San Joaquin River, the delta, and San Francisco Bay. Organochlorine compounds accumulate in bivalves and sediment and may pose a problem to other biotic species in this watershed.

Pérès, F., M. Coste, F. Ricard and A. Boudou. 1997. Effects of methylmercury and inorganic mercury on periphytic diatom communities in freshwater indoor microcosms. Journal of Applied Phycology 9(3):215-227.

The effects of inorganic mercury (HgII) and methylmercury (MeHg) on the colonization of artificial substrates by periphytic diatoms were studied using indoor freshwater microcosms. These consisted of a mixed biotope--water column + natural sediment--with rooted macrophyte cuttings (Elodea densa) and benthic bivalve molluscs (Corbicula fluminea). The periphyton was collected on glass slides in the water column after 34 and 71 days. The two Hg sources were introduced either by daily additions to the water column, or once at the beginning into the sediment, using two nominal concentrations: water column, 0.5 μg/L and 2 μg/L for both compounds: sediment, 0.5 mg/kg (fw) and 2 mg/kg (fw) for MeHg and 1 mg/kg (fw) and 10 mg/kg (fw) for HgII. Several complementary criteria were used to analyze the structural and functional perturbations induced: cell density, species richness, diatom size, relative abundance. Exposure to MeHg added to the water column resulted in reduced cell density and changes in species composition with enhancement of e.g. Fallacia pygmaea or Nitzschia palea; inorganic Hg had less effect on the population structure. After contamination via the sediment, the effects of the two compounds were less pronounced than for the water source.

Peres, F., D. Florin, T. Grollier, A. Feurtet-Mazel, M. Coste, F. Ribeyre, M. Ricard and A. Boudou. 1996. Effects of the phenylurea herbicide Isoproturon on periphytic diatom communities in freshwater indoor microcosms. Environmental Pollution 94(2):141-152.

The toxic effects of the phenylurea herbicide Isoproturon-IPU: (3-(4-isopropylphenyl)-1, 1-dimethylurea)-were studied on the colonization of periphytic diatom communities, within indoor microcosms consisting of a mixed biotope (water column and natural sediment) and two biological species-rooted macrophyte cuttings (Elodea densa) and benthic bivalve molluscs (Corbicula fluminea). The periphyton, essentially composed of diatoms, was collected on artificial substrata (glass slides) in the upper layers of the water column, after two periods of exposure (34 and 71 days). IPU was initially added in the water or in the sediment compartment, at two nominal concentrations (L1 and L2 levels) for each contamination source-5 and 20 μg litre^-1 and 100 and 400 μg kg^-1 in sediment (w/w) respectively. The effects of IPU on the density and community structure of periphytic diatoms are described. A marked reduction in the diatom density was observed after 34 days exposure to the lower concentration of IPU in the water (5 μg litre^-1). For the L2 levels, the very small number of live cells present did not permit quantification of the diatom density. After 71 days, recovery in community parameters occurred for the two contamination levels of the sediment and water column sources. Samples collected in the experimental units contaminated with the L2 levels were dominated by heterotrophic and smaller diatom species, such as Sellaphora seminulum. Data treatment based on factorial discriminant analysis enabled us to distinguish the different contamination conditions, with only 11 species from the 130 taxa identified.

Perry, M. C. and F. M. Uhler. 1981. Asiatic clam (Corbicula manilensis) and other foods used by waterfowl in the James River, Virginia. Estuaries 4(3):229 233.

Peso, J. and J. A. Bechara. 1999. Estructura del zoobentos del embalse de Yacyreta, Argentina en dos estaciones demuestreo,antes y despues del llenado a cota 76 m s.n.m. [Zoobenthos community structure at two sampling sites of Yacyreta Dam, before and after the filling of the reservoir (Parana River, Argentina)]. Revista de Ictiologia, Corrientes Numero Especial 7:37-47. [Spanish with English summary]

The results of a field sampling program aimed to know qualitative and quantitative changes of the benthic community structure before and after the rising of the Yacyreta Reservoir water level, are described. Studies were carried out from samples obtained every 30 days (May 1993 - July 1995) at two localities : Puerto Nemesio Parma and Puerto Valle (corresponding to transition and reservoir reaches, respectively). At each site, two replicated samples were taken using a Tamura dredge. Species composition, richness, diversity (Shannon and Wiener) and density (ind.m^-2) were employed in the description of the benthic community. In a total of 66 sampling units, 46 taxa were identified at the transition site, while 53 of them were found at the reservoir site (total of 69 taxa). After the filling of the reservoir, diversity decreased and density remained constant at the transition site. The contrary occurred at the reservoir site. At both sites, the most frequent and abundant species were Pristina americana, Aulodrilus pigueti and Botrhioneurum americanus (Oligochaeta), Polypedilum sp, Cryptochironomus sp.(Chironomidae, Diptera) and an exotic bivalve, Corbicula fluminea. A correspondence analysis showed a clear difference between transition and reservoir sites before the filling of the reservoir, with the presence of many species typical of lotic habitats. In a few months, the benthic community structure changed and was very similar in both sampling sites, with dominance of Oligochaeta and Chironomidae, being also less variable in time. Some of the possible causes of the observed changes are discussed, including the joint effects of water velocity decrease, the settlement of fine particles, and the reduction of bottom granulometry in the sampling areas.

Peterson, M. J., G. R. Southworth and K. D. Ham. 1994. Effect of sublethal chlorinated discharges on PCB accumulation in transplanted Asiatic clams (Corbicula fluminea). Water, Air, and Soil Pollution 73(1-4):169-178.

From 1987-1990, uncontaminated Asiatic clams (Corbicula fluminae) were placed in cages and transplanted into two streams receiving industrial discharges to help identify and quantify polychlorinated biphenyl (PCB) contamination to the streams. Clams accumulated substantial PCB residues at most sites monitored, with the exception of the sites closest to chlorinated discharges. Clams placed nearest to the chlorinated stream reaches consistently underestimated PCB contamination, based on the amount of PCBs found in fish and sediment at those sites. In a separate experiment, clams exposed in stream-side tanks to untreated (total residual chlorine ranged from 0.02-0.07/mg L daily) and dechlorinated stream water exhibited differing degrees of valve movement, growth, and PCB accumulation after a four-week exposure to the two treatments. Clams exposed to untreated (chlorinated) stream water closed their shells more often, exhibited less growth, and accumulated substantially lower PCB concentrations than clams exposed to dechlorinated stream water. Clams apparently close their shells to avoid chlorine exposure, thus isolating clam tissues from PCBs found in the stream water and in the clams' food. Because chlorine and PCBs occur together in many industrial discharges, this finding is a significant consideration for monitoring programs that utilize clams to assess PCB bioavailability.

Petit Marie, N., L. Casta, G. Delibrias and C. Gaven. 1980. Preliminary data of Quaternary paleolacustrine deposits in the Wadi ash Shati area, Libya.