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‣ Massive die-offs of freshwater bivalves as resource pulses

Sousa, Ronaldo; Varandas, S.; Cortes, R.; Teixeira, Amílcar; Lopes-Lima, Manuel; Machado, Jorge; Guilhermino, Lúcia
Fonte: EDP Sciences Publicador: EDP Sciences
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
48.64653%
The winter of 2009/2010 was particularly severe in Northern Portugal resulting in higher river flow levels. A study was undertaken to assess the impact of this situation on several populations of freshwater bivalves (e.g., Anodonta anatina, Corbicula fluminea, Margaritifera margaritifera, Potomida littoralis and Unio delphinus) in the catchments of the Rivers Minho, Douro, Taˆ mega, Tua and Sabor. Massive die-offs occurred for all species in all rivers, resulting in the removal of great numbers and biomass from the riverbed to the adjacent riverbanks, reaching maximum values of 2280 individuals.mx2 and 10 225 g wet weight.mx2, respectively. The invasive Asian clam C. fluminea had both highest density and biomass (however, this invasive bivalve is not dominant in several surveyed sites, and some rivers are still not colonized by this species). Results show that the quantitative and qualitative importance of this carrion transfer to the riverbank should be incorporated in future studies on the assessment of ecosystem function, contributing to a better understanding of the role of freshwater bivalves as resource pulses in adjacent terrestrial habitats. Some of the affected species have conservational importance and these extreme climatic events are predicted to increase in the future. These massive die-off events should be incorporated into management plans and selected restoration measures such as rapid relocation of endangered native mussels back to the riverbed can be easily applied to lessen possible impacts.

‣ Impactos ambientais em ecossistemas lóticos do norte de Portugal. Estudo da bio-ecologia e fisiologia de Anodonta anatina (L.) (Bivalvia, Unionidae)

Nogueira, Mónica Sofia Reis
Fonte: Instituto Politécnico de Bragança, Escola Superior Agrária Publicador: Instituto Politécnico de Bragança, Escola Superior Agrária
Tipo: Dissertação de Mestrado
Português
Relevância na Pesquisa
28.449248%
São vários os impactos ambientais que ameaçam os ecossistemas dulçaquícolas, sendo responsáveis pela diminuição e extinção de muitas populações, muitas delas pertencentes a bivalves de água doce. Fenómenos como a regularização de caudais, poluição, eutroficação e degradação do habitat aquático e ribeirinho são os principais factores que originam a diminuição das populações de Unionoida. Neste estudo foi seleccionada a espécie-alvo Anodonta anatina (L.), um bivalve que habita os sectores médio e terminal dos rios Sabor, Tua e Tâmega, no Nordeste de Portugal. Avaliaram-se diferentes aspectos relacionados com a bio-ecologia e fisiologia da espécie, especialmente associada à reprodução. Foi detectada a ocorrência simultânea de exemplares dióicos e outros hermafroditas, provavelmente como resposta adaptativa a flutuações nas condições ambientais e na dinâmica populacional. Verificou-se ainda que para A. anatina todas as espécies piscícolas autóctones testadas (truta, escalo, bordalo, ruivaco, boga, barbo e verdemã) e apenas uma espécie exótica (truta arco-íris) funcionaram como hospedeiros desta espécie. Este facto tem elevada relevância em termos de conservação da espécie, uma vez que a dominância de espécies piscícolas em albufeiras de barragens inviabiliza...

‣ Biology and conservation of freshwater bivalves: past, present and future perspectives

Lopes-Lima, Manuel; Teixeira, Amílcar; Froufe, Elsa; Lopes, Anabela; Varandas, Simone; Sousa, Ronaldo
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
69.176445%
Freshwater bivalves have been highly threatened by human activities, and recently their global decline has been causing conservational and social concern. In this paper, we review the most important research events in freshwater bivalve biology calling attention to the main scientific achievements. A great bias exists in the research effort, with much more information available for bivalve species belonging to the Unionida in comparison to other groups. The same is true for the origin of these studies, since the publishing pattern does not always correspond to the hotspots of biodiversity but is concentrated in the northern hemisphere mainly in North America, Europe and Russia, with regions such as Africa and Southeast Asia being quite understudied. We also summarize information about past, present and future perspectives concerning the most important research topics that include taxonomy, systematics, anatomy, physiology, ecology and conservation of freshwater bivalves. Finally, we introduce the articles published in this Hydrobiologia special issue related with the International Meeting on Biology and Conservation of Freshwater Bivalves held in 2012 in Bragança, Portugal.

‣ Assessment of Ametryn Contamination in River Water, River Sediment, and Mollusk Bivalves in Sao Paulo State, Brazil

JACOMINI, Analu Egydio; CAMARGO, Plinio Barbosa de; AVELAR, Wagner Eustaquio Paiva; BONATO, Pierina Sueli
Fonte: SPRINGER Publicador: SPRINGER
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
39.03481%
Sao Paulo state, Brazil, is one of the main areas of sugar cane agriculture in the world. Herbicides, in particular, ametryn, are extensively used in this extensive area, which implies that this herbicide is present in the environment and can contaminate the surface water by running off. Thereby, residues of ametryn were analyzed in samples of river water an river sediment and in freshwater bivalves obtained from the rivers Sapucai, Pardo and Mogi-Guacu in Sao Paulo State, Brazil. Samples were taken in the winter of 2003 and 2004 in two locations in each river. The specimens of freshwater bivalves collected and analyzed were Corbicula fluminea, an exotic species, and Diplodon fontaineanus, a native species. Additionally, the evaluation of the ability of bioconcentration and depuration of ametryn by the freshwater bivalve Corbicula fluminea was also performed. Ametryn concentrations in the samples were measured by liquid chromatography coupled to mass spectrometry. Residues of ametryn in water (50 ng/L) and in freshwater bivalves (2-7 ng/g) were found in the Mogi-Guacu River in 2004, and residues in river sediments were found in all rivers in 2003 and 2004 (0.5-2 ng/g). The observation of the aquatic environment through the analysis of these matrixes...

‣ Permian non-marine bivalves of the Falkland Islands and their palaeoenvironmental significance

Simões, Marcello G.; Quaglio, Fernanda; Warren, Lucas V.; Anelli, Luiz Eduardo; Stone, Philip; Riccomini, Claudio; Grohmann, Carlos Henrique; Chamani, Marlei A. C.
Fonte: TAYLOR & FRANCIS LTD; ABINGDON Publicador: TAYLOR & FRANCIS LTD; ABINGDON
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
38.339497%
We describe the occurrence of non-marine bivalves in exposures of the Middle Permian (Capitanian) Brenton Loch Formation on the southern shore of Choiseul Sound, East Falklands. The bivalves are associated with ichnofossils and were collected from a bed in the upper part of the formation, within a 25 cm thick interval of dark siltstones and mudstones with planar lamination, overlain by massive sandstones. The shells are articulated, with the valves either splayed open or closed. At the top of the succession, mudstone beds nearly 1.5 m above the bivalve-bearing layers yielded well-preserved Glossopteris sp. cf. G. communis leaf fossils. The closed articulated condition of some shells indicates preservation under high sedimentation rates with low residence time of bioclasts at the sediment/water interface. However, the presence of specimens with splayed shells is usually correlated to the slow decay of the shell ligament in oxygen-deficient bottom waters. The presence of complete carbonized leaves of Glossopteris associated with the bivalve-bearing levels also suggests a possibly dysoxic-anoxic bottom environment. Overall, our data suggest that the bivalves were preserved by abrupt burial, possibly by distal sediment flows into a Brenton Loch lake...

‣ Reprodução e cultivo de bivalves límnicos ameaçados de extinção: uma estratégia para a conservação do gênero Diplodon (Spix, 1827) (Mollusca, Hyriidae); Reproduction and cultivation of threatened freshwater mussels: a strategy for the conservation of the genus (Spix, 1827) (Mollusca, Hyriidae)

Lima, Ricardo Cunha
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 31/05/2010 Português
Relevância na Pesquisa
29.254285%
Os bivalves límnicos, ou náiades da ordem Unionoida, representando a maior radiação dos bivalves na água doce, com seis famílias, 181 gêneros e 800 espécies, sendo encontrados em todos os continentes, e atualmente, representam o grupo de animais de água doce em maior risco de extinção. A causa mais dramática do declínio e extinção dos bivalves dulcícolas é a modificação e destruição do seu habitat, as mudanças climáticas globais e a introdução de animais aquáticos exóticos (não nativos) Este táxon é o único membro da classe Bivalvia reconhecidos por apresentar um estágio larval parasita em seu ciclo de vida, o qual envolve uma relação obrigatória com um hospedeiro vertebrado, normalmente um peixe, e uma larva altamente modificada, o gloquídio ou lasídio. Esta característica do ciclo de vida é um componente principal de qualquer plano de conservação dos bivalves límnicos. Com a finalidade de propagar as espécies que estão em perigo de extinção, pretendeu-se desenvolver técnicas viáveis para a obtenção de formas juvenis em laboratório, através do cultivo artificial (in vitro) dos gloquídios. Através da metodologia empregada foi possível obter indivíduos juvenis com mais de 30 dias das espécies D. expansus...

‣ Permian non-marine bivalves of the Falkland Islands and their palaeoenvironmental significance

Simoes, Marcello G.; Quaglio, Fernanda; Warren, Lucas V.; Anelli, Luiz E.; Stone, Philip; Riccomini, Claudio; Grohmann, Carlos H.; Chamani, Marlei A. C.
Fonte: Taylor & Francis Ltd Publicador: Taylor & Francis Ltd
Tipo: Artigo de Revista Científica Formato: 543-554
Português
Relevância na Pesquisa
38.339497%
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); We describe the occurrence of non-marine bivalves in exposures of the Middle Permian (Capitanian) Brenton Loch Formation on the southern shore of Choiseul Sound, East Falklands. The bivalves are associated with ichnofossils and were collected from a bed in the upper part of the formation, within a 25 cm thick interval of dark siltstones and mudstones with planar lamination, overlain by massive sandstones. The shells are articulated, with the valves either splayed open or closed. At the top of the succession, mudstone beds nearly 1.5 m above the bivalve-bearing layers yielded well-preserved Glossopteris sp. cf. G. communis leaf fossils. The closed articulated condition of some shells indicates preservation under high sedimentation rates with low residence time of bioclasts at the sediment/water interface. However, the presence of specimens with splayed shells is usually correlated to the slow decay of the shell ligament in oxygen-deficient bottom waters. The presence of complete carbonized leaves of Glossopteris associated with the bivalve-bearing levels also suggests a possibly dysoxic-anoxic bottom environment. Overall...

‣ Fouling of European freshwater bivalves (Unionidae) by the invasive zebra mussel (Dreissena polymorpha)

Sousa, Ronaldo Gomes; Pilotto, Francesca; Aldridge, David C.
Fonte: Wiley Publicador: Wiley
Tipo: Artigo de Revista Científica
Publicado em //2011 Português
Relevância na Pesquisa
37.697144%
1. The zebra mussel (Dreissena polymorpha) is well known for its invasive success and its ecological and economic impacts. Of particular concern has been the regional extinction of North American freshwater mussels (Order Unionoida) on whose exposed shells the zebra mussels settle. Surprisingly, relatively little attention has been given to the fouling of European unionoids. 2. We investigated interspecific patterns in fouling at six United Kingdom localities between 1998 and 2008. To quantify the effect on two pan-European unionoids (Anodonta anatina and Unio pictorum), we used two measures of physiological status: tissue mass : shell mass and tissue glycogen content. 3. The proportion of fouled mussels increased between 1998 and 2008, reflecting the recent, rapid increase in zebra mussels in the U.K. Anodonta anatina was consistently more heavily fouled than U. pictorum and had a greater surface area of shell exposed in the water column. 4. Fouled mussels had a lower physiological condition than unfouled mussels. Unlike tissue mass : shell mass ratio, tissue glycogen content was independent of mussel size, making it a particularly useful measure of condition. Unio pictorum showed a stronger decline in glycogen with increasing zebra mussel load...

‣ Biology and conservation of freshwater bivalves : past, present and future perspectives

Lima, Manuel Lopes; Teixira, Amílcar; Froufe, Elsa; Lopes, Anabela; Varandas, Simone; Sousa, Ronaldo Gomes
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Artigo de Revista Científica
Publicado em //2014 Português
Relevância na Pesquisa
69.176445%
Freshwater bivalves have been highly threatened by human activities, and recently their global decline has been causing conservational and social concern. In this paper, we review the most important research events in freshwater bivalve biology calling attention to the main scientific achievements. A great bias exists in the research effort, with much more information available for bivalve species belonging to the Unionida in comparison to other groups. The same is true for the origin of these studies, since the publishing pattern does not always correspond to the hotspots of biodiversity but is concentrated in the northern hemisphere mainly in North America, Europe and Russia, with regions such as Africa and Southeast Asia being quite understudied. We also summarize information about past, present and future perspectives concerning the most important research topics that include taxonomy, systematics, anatomy, physiology, ecology and conservation of freshwater bivalves. Finally, we introduce the articles published in this Hydrobiologia special issue related with the International Meeting on Biology and Conservation of Freshwater Bivalves held in 2012 in Braganc¸a, Portugal.

‣ Invasive bivalves in fresh waters : impacts from individuals to ecosystems and possible control strategies

Sousa, Ronaldo Gomes; Novais, Adriana Araújo; Costa, R.; Strayer, David L.
Fonte: Springer Publicador: Springer
Tipo: Artigo de Revista Científica
Publicado em //2014 Português
Relevância na Pesquisa
38.716123%
Invasive bivalves may cause great ecological, evolutionary, and economic impacts in freshwater ecosystems. Species such as Corbicula fluminea, Dreissena bugensis, Dreissena polymorpha, Limnoperna fortunei, and Sinanodonta woodiana are widely distributed hyper-successful invaders, but several others not yet invasive (or at least not considered as such) may become so in the near future. These species can affect hydrology, biogeochemical cycling, and biotic interactions through several mechanisms, with impacts ranging from individuals to ecosystems. Freshwater invasive bivalves can create no-analog ecosystems, posing serious difficulties for management, but new techniques are becoming available which may enhance options to detect early introductions and mitigate impacts. Although knowledge about the biology of these bivalves has increased considerably in the last two decades, several fundamental gaps still persist; we suggest new research directions that are worth exploring in the near future.

‣ Morphological and chemical characterization of mineral concretions in the freshwater bivalve Anodonta cygnea (Unionidae)

Hinzmann, Mariana F.; Lima, Manuel Lopes; Bobos, Iuliu; Ferreira, Jorge Amaral; Domingues, Bernardo; Machado, Jorge
Fonte: Laboratório Nacional de Energia e Geologia Publicador: Laboratório Nacional de Energia e Geologia
Tipo: Artigo de Revista Científica
Publicado em /01/2015 Português
Relevância na Pesquisa
37.894426%
The freshwater mussel Anodonta cygnea is commonly used as a model organism for biomineralization studies, its peculiar morphofunctional properties also make it an excellent environmental biomonitor. The first detailed on the calcareous concretions from gill and mantle tissue, as well as fluids of the freshwater bivalve A. cygnea, supported by histological, scanning, spectrometry, and spectroscopy analyses. Through these analyses, the morphology, structure, and chemical characterization of these biomineral concretions were accomplished. The concretions represent a high percentage of the dry weight of these organisms. In gill tissue, it can reach up to 50% of dry weight prior to reproductive maturity. Analysis of elemental composition of the tissue concretions showed the presence of calcium and phosphate, as main components, associated with other residual elements like iron, manganese, magnesium, and zinc. Concretions are arranged in concentric alternated layers of organic and inorganic matrix. The shape and size of the concretions vary substantially, from very small, less than 1 µm diameter with very regular round structure, found mainly in the mantle tissue, to more than 50 µm length with irregular globular clusters...

‣ Biomineralization studies on cellulose membrane exposed to biological fluids of Anodonta cygnea

Lopes, Anabela; Lima, Manuel Lopes; Ferreira, Jorge Amaral; Araújo, Sandra; Hinzmann, Mariana F.; Oliveira, José; Rocha, António; Domingues, Bernardo; Bobos, Iuliu; Machado, Jorge
Fonte: Laboratório Nacional de Energia e Geologia Publicador: Laboratório Nacional de Energia e Geologia
Tipo: Artigo de Revista Científica
Publicado em /06/2014 Português
Relevância na Pesquisa
38.190713%
The present work proposes to analyse the results obtained under in vitro conditions where cellulose artificial membranes were incubated with biological fluids from the freshwater bivalve Anodonta cygnea. The membranes were mounted between two half ‘Ussing chambers’ with different composition solutions in order to simulate epithelial surfaces separating organic fluid compartments. The membrane surfaces were submitted to two synthetic calcium and phosphate solutions on opposite sides, at pH 6.0, 7.0 or 9.0 during a period of 6 hours. Additional assays were accomplished mixing these solutions with haemolymph or extrapallial fluid from A. cygnea, only on the calcium side. A selective ion movement, mainly dependent on the membrane pore size and/or cationic affinity, occurred with higher permeability for calcium ions to the opposite phosphate chamber supported by calcium diffusion forces across the cellulose membrane. In general, this promoted a more intense mineral precipitation on the phosphate membrane surface. A strong deposition of calcium phosphate mineral was observed at pH 9.0 as a primary layer with a homogeneous microstructure, being totally absent at pH 6.0. The membrane showed an additional crystal phase at pH 7.0 exhibiting a very particular hexagonal or cuttlebone shape...

‣ Freshwater sponges (Porifera, Demospongiae) in a benthic filter feeding community at the Guanacaste Dry Forest, Costa Rica

Volkmer-Ribeiro,Cecilia; Machado,Vanessa de S
Fonte: Fundação Zoobotânica do Rio Grande do Sul Publicador: Fundação Zoobotânica do Rio Grande do Sul
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2009 Português
Relevância na Pesquisa
37.894426%
The freshwater sponges Trochospongilla variabilis Bonetto & Ezcurra de Drago (1973), Radiospongilla crateriformis (Potts, 1882), Spongilla cenota Penney & Racek (1968) and Corvoheteromeyenia heterosclera (Ezcurra de Drago, 1974) compose with the sphaerid bivalve Eupera cubensis (Prime, 1865) and several Phylactolaemata bryozoans a benthic filter feeding community living in seasonal lentic and lotic habitats with high Particulate Organic Carbon (POC), low conductivity and acid pH within the Costa Rica Dry Forest biome. The sponge specimens gathered led to the re-description of the four species.

‣ First records of Freshwater Bivalves of Ilha Grande National Park, Paraná, Brazil

Ragonha,Flávio Henrique; Pinha,Gisele Daiane; Petsch,Danielle Katharine; Mansur,Maria Cristina Dreher; Takeda,Alice Michiyo
Fonte: Fundação Zoobotânica do Rio Grande do Sul Publicador: Fundação Zoobotânica do Rio Grande do Sul
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2014 Português
Relevância na Pesquisa
48.991245%
The Ilha Grande National Park, Paraná, Brazil, is located in the Upper Paraná River and has characteristics typical of a floodplains. This protected area includes lagoons connected and disconnected to the Paraná River, although the latter also connect during periods of high water level, thus composing a heterogeneous group of lacustrine environments. The enormous potential the flora and fauna diversities are still little known to the region, as can be seen through benthic invertebrates, inclunding bivalves mollusks. The granulometric composition of these floodplain lagoons was formed mainly by mud and very fine sand. Furthermore, organic matter composition was predominantly of fine particulate. The other abiotic factors differed from lagoons located within the island of the park to those located in the left margin of Paraná River. The results demonstrated the importance of abiotic factors such as the physical composition of granulometric texture, organic matter and macrophyte banks, to the establishment of bivalves in these floodplain lagoons. We recorded bivalves of Pisidium (native), Diplodon (native), and Corbicula (invasive). The highest values of Diplodon sp. density were observed at São João/C lake, for Pisidium sterkianum (Pilsbry...

‣ Rapid evolution of sessility in an endemic species flock of the freshwater bivalve Corbicula from ancient lakes on Sulawesi, Indonesia

von Rintelen, Thomas; Glaubrecht, Matthias
Fonte: The Royal Society Publicador: The Royal Society
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
37.697144%
The fauna of ancient lakes frequently contains taxa with highly derived morphologies that resulted from in situ radiation of lacustrine lineages with high antiquity. We employed a molecular mtDNA phylogeny to investigate this claim for corbiculid freshwater bivalves in two ancient lake systems on the Indonesian island Sulawesi. Among the otherwise mobile corbiculid species flock, only one taxon, Posostrea anomioides, in the ancient Lake Poso exhibits a unique habit, i.e. cementing one valve to the substrate. Our data show that Corbicula on Sulawesi is polyphyletic, with the endemic riverine taxa in terminal position, and the lacustrine species flock being paraphyletic. Surprisingly, Posostrea is not confirmed as a genus distinct from Corbicula and genetic distances suggest a rather recent origin from the only other corbiculid species endemic to Lake Poso, the non-cementing Corbicula possoensis. While the cementing anomioides, despite its unique behavioural and morphological characteristics, clusters together with non-sessile Corbicula species, the latter exhibit strong genetic distances in the absence of morphological disparity and fall into several genetically rather distinct clades. These findings suggest that developmental plasticity of animals in ancient lakes rather than the antiquity of lineages might account for the unique morphology of some species.

‣ Physico-chemical variables determining the invasion risk of freshwater habitats by alien mollusks and crustaceans

Früh, Denise; Stoll, Stefan; Haase, Peter
Fonte: Blackwell Publishing Ltd Publicador: Blackwell Publishing Ltd
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
28.646528%
The aim of this study was to assess the invasion risk of freshwater habitats and determine the environmental variables that are most favorable for the establishment of alien amphipods, isopods, gastropods, and bivalves. A total of 981 sites located in streams and rivers in Germany. Therefore we analyzed presence–absence data of alien and indigenous amphipods, isopods, gastropods, and bivalves from 981 sites located in small to large rivers in Germany with regard to eight environmental variables: chloride, ammonium, nitrate, oxygen, orthophosphate, distance to the next navigable waterway, and maximum and minimum temperature. Degraded sites close to navigable waters were exposed to an increased invasion risk by all major groups of alien species. Moreover, invaded sites by all four groups of alien species were similar, whereas the sites where indigenous members of the four groups occurred were more variable. Increased temperature and chloride concentration as well as decreased oxygen concentration were identified as major factors for the invasibility of a site. Species-specific analyses showed that chloride was among the three most predictive environmental variables determining species assemblage in all four taxonomic groups. Also distance to the next navigable waterways was similarly important. Additionally...

‣ Base de dados direcionada à elaboração de um programa de monitoramento de águas continentais utilizando moluscos bivalves

Callil, Claudia Tasso
Fonte: Pontifícia Universidade Católica do Rio Grande do Sul; Porto Alegre Publicador: Pontifícia Universidade Católica do Rio Grande do Sul; Porto Alegre
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
48.339497%
Os trabalhos que compõe o corpo desta tese oferecem informações sobre aspectos biológicos e ecológicos de moluscos bivalves que ocorrem no estado de Mato Grosso. Registros pioneiros tratando sobre: 1 - morfologia ultraestrual das conchas, 2 - comportamento populacional frente a parâmetros biométricos, 3 – gametogênese e ciclo sexual, e 4 - padrões relacionados a seleção de partículas, taxa de filtração e respiração, são considerados para duas espécies de Anodontites Bruguière, 1792, gênero de ocorrência exclusiva na América do Sul. Utilizando abordagens de morfologia funcional, ecologia de populações e experimental, os principais resultados obtidos foram: 1 - A. trapesialis (LAMARCK, 1819) e A. elongatus (SWAINSON, 1823) possuem valvas constituídas por três segmentos, perióstraco, camada prismática e camada nacarada, semelhante aos demais Unionoida. Estruturas como pregas, arcos, microsestrias e espículas são descritas e diferenciadas para cada uma das espécies; 2 - quando comparadas populações provenientes de diferentes locais, ambas as espécies apresentaram diferenças significativas frente às variáveis peso da concha e altura, ficando demonstrado que as espécies apresentam plasticidade fenotípica decorrentes de diferenças ambientais; 3 – as duas espécies são espermatozeugmatas...

‣ State of the art in taxonomy of Chilean freshwater bivalves: Advances and difficulties

Fonte: Universidade Católica de Temuco Publicador: Universidade Católica de Temuco
Tipo: Artículo de Revista
Português
Relevância na Pesquisa
38.190713%
An update of the Chilean freshwater bivalve taxonomy is presented. The bivalves described at present are adscribed to two families: Hyriidae represented only by the genus Diplodon with two species (D. chilensis and D. solidulus) and Sphaeriidae represented by three genera: Pisidium with seven species (P. chilense, P. magellanicum, P. lebruni, P. observationis, P. meierbrooki, P. huillichum and P. llanquihuense), Sphaerium with two species (S. lauricochae and S. forbesi), and Musculium with two species (M. argentinum and M. patagonicum). Sub-generic and sub-specific taxa are recognized for Hyriidae only. The present study includes the synonymy, type locality and geographic distribution where the species have been recorded. The most reliable diagnostic features for Hyriidae species identification are the hinge morphology in adult specimens, the presence or absence of the valve teeth, and their position and shape in larvae. At the generic level within Sphaeriidae, the most reliable taxonomic characters are the morphology and number of the siphons, and the size of both demibranchs. At the species level these characters are valve morphometry and morphology, which includes beak position, hinge features, shape and size of cardinal teeth, valve sculpture and pore density of the inner surface of valves. Results are discussed regarding advances and conflicts related to the taxonomic and systematic arrangement in both families...

‣ Paleoautoecologia dos bivalves do Grupo Passa Dois (Neopermiano), no Estado de São Paulo |b bivalves fósseis como indicadores da dinâmica sedimentar; Not available.

Ghilardi, Renato Pirani
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 28/07/1999 Português
Relevância na Pesquisa
39.387407%
No presente estudo é realizada uma análise morfofuncional (paleoautoecológica) dos bivalves das formações Serra Alta, Terezina e Corumbataí, Grupo Passa Dois, Neopermiano, que ocorrem nas assembléias de Anhembia froesi, Pinzonella illusa e Pinzonella neotropica, no Estado de São Paulo. O estudo teve por objetivo a reconstrução do habito de vida destes invertebrados como ponto de partida para a discussão de aspectos paleoecológicos mais amplos. Na assembléia de Anhembia froesi (Formação Serra Alta e base da Formação Corumbataí), ocorrem bivalves escavadores rasos, lentos (Anhembia froesi, Tambaquyra camargoi, Mendesia piracicabensis, Maackia contorta), de semi-infauna (Barbosaia angulata) e epifauna (?Anthraconaia mezzalirai) bissadas. Na assembléia de Pinzonella illusa (formações Serra Alta e Corumbataí), com maior diversidade de guildas, predominam os bivalves escavadores rasos, lentos (Pinzonella illusa, Plesiocyprinella carinata, Ferrazia cardinalis, Terraiopsis aequilateralis e Othonella araguaiana), sendo encontrados, também, escavadores rasos, rápidos (Favalia arcuata, Holdhausiella elongata e Runnegariella fragilis) ou escavadores intermediários (Casterella gratiosa, Itatamba paraima). Evidências morfofuncionais (e.g....

‣ First records of freshwater molluscs from the ecological reserve El Edén, Quintana Roo, México

Cózatl-Manzano,Roberto; Naranjo-García,Edna
Fonte: Instituto de Biología Publicador: Instituto de Biología
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2007 Português
Relevância na Pesquisa
38.01583%
The diversity of the freshwater molluscs at El Edén was unknown. This is the first treatment of them, allowing us to compare spatial and temporal species distribution. Eleven species of freshwater molluscs were found in 2 surveys carried in March (dry season) and September (rainy season) 1998 at the reserve El Edén. A total of 266 individuals were collected; 8 pulmonates, Mayabina spiculata, Mexinauta impluviatus, Physa sp., Biomphalaria havanensis, Drepanotrema lucidum, Drepanotrema kermatoides, Planorbella (Pierosoma) trivolvis, and Planorbula armigera; 2 prosobranchs, Pyrgophorus sp. and Pomacea flagellata; and one bivalve, Musculium transversum. Pulmonata dominate over Prosobranchia species in diversity. No significant differences were observed in diversity between dry and rainy seasons. However, species abundance recorded in both seasons was very low, probably due to a combination of inadequate food resources and disadvantageous climate (periodic conditions of drought and flooding). Further studies using a combination of different sampling methods and more frequent samplings are needed to confirm or identify these factors. We suggest that future studies should focus on cultivation of species with economic potential such as the apple snail Pomacea flagellata.