Thesis (M.S.)--Missouri State University, 2009. / "May 2009." Includes bibliographical references (leaves 27-34). Also available online.

No description available.

The lack of any measurements of the secondary production of the prosobranch snail Sulcospira hainanensis (Bröt, 1872) (Pachychilidae), an abundant primary consumer in Hong Kong streams, represents a major gap in our knowledge of the magnitude of benthic productivity in these systems where S. hainanensis constitutes a substantial proportion of community biomass. This study investigated the population dynamics and production of S. hainanensis between February 2011 and February 2012 in 4 Hong Kong streams (2 unshaded and 2 shaded). Annual production by amphibiotic insects was also quantified by emergence traps to evaluate the importance of in-stream production by fully aquatic animals versus that leaving streams in the form of adult aquatic insects. In addition, snail grazing effects on algae and the potential for consequent competitive interactions with benthic insects was compared under different shading conditions and between wet and dry seasons. Sulcospira hainanensis was ovoviviparous and had balanced sex ratios. Brood size ranged from 52 to 1189, and 3 recruitment episodes were observed in both populations in the one-year study period. Hatchlings reached sexual maturity in 3 – 5 years whereas adults could live for 6 – 12 years. Mean population densities varied from 108.4 to 206.1 individuals m^(-2), while mean biomass was 1003.0 to 4430.2 mg ash-free dry mass (AFDM) m^(-2) and was generally higher in the dry season. Snail production was estimated using the size-frequency, instantaneous-growth (field- and computer-based) and increment-summation (IS) methods, with the IS estimates (1612.8 – 6123.9 mg AFDM m^(-2) 〖year〗^(-1)) considered to most accurately represent production by S. hainanensis. Annual turnover ratios were 1.36 – 2.24 〖year〗^(-1), and production was higher in unshaded streams where growth was more rapid, reflecting higher availability of algal food. The contribution of S. hainanensis to production by benthic animals as previously estimated in one study site was relatively low (15%) compared with its contribution to total standing biomass (26%). Annual insect emergence varied from 167.5 – 780.2 mg AFDM m-2 year-1, and constituted ~13% of total benthic production in one site, and this preliminary finding suggests that the water-to-land energy flux attributable to emerging insects along tropical Hong Kong streams is rather minor. The competition effects of S. hainanensis were studied during the dry season of 2012 and the wet season of 2011 by means of snail inclusion-exclusion manipulations. Snails exerted strong effects on algae and insects during the dry season, but did not significantly affect the structure of benthic assemblages. Algae in shaded streams were more severely depleted by snails, though the reduction in snail densities did not lead to increases in insect abundance or biomass. The effects of snails were not detectable during the wet season, when spate-induced disturbances were more frequent and intense. This generally agreed with the harsh-benign hypothesis, which predicts a reduction in the significance of biotic interactions under more disturbed conditions. Therefore, competition between S. hainanensis and insects was important only at base-flow conditions during the dry season. / published_or_final_version / Biological Sciences / Master / Master of Philosophy

Thesis (M.S.)--University of Northern British Columbia, 2000. / Includes bibliographical references (leaves 99-105).

Invasions of ecosystems by exotic species are increasing and they may often act as a significant driver of the homogenization of the Earth’s biota, resulting in global biodiversity loss. Moreover, the addition of exotic species may have dramatic effects on ecosystem structure and functioning which may result in the extirpation of indigenous species. In 2004, a large population of an unknown lymnaeid was found in the Amatikulu Hatchery, northern KwaZulu-Natal, South Africa, and was subsequently found in few garden fish ponds in Durban. In 2007, it was identified using molecular techniques as Radix rubiginosa (Michelin, 1831) – a species widespread in southeast Asia. An invasion by R. rubiginosa is however likely to go unnoticed because its shell morphology resembles some forms of the highly variable and widely distributed indigenous lymnaeid, Lymnaea natalensis Krauss, 1848. Accurate and “easy” species identifications would permit the ready assessment of introduction histories and distributions, but in the present case identification was difficult due to unclear and contradicting accounts of the indigenous L. natalensis in the literature. A redescription of L. natalensis with emphasis on conchological and anatomical characteristics was therefore presented. This will help to distinguish variation between R. rubiginosa and L. natalensis and also assist those carrying out rapid bioassessment (SASS) surveys in South African rivers in recognising R. rubiginosa should it spread. For this, shells of R. rubiginosa and L. natalensis from both the UKZN Pond and the Greyville Pond were selected into either size class 1 (shell length < 10 mm) or size class 2 (shell length ≥ 10 mm). Six shell characters, shell length (height), shell width, aperture length (height), aperture width, length of last body whorl and spire height for each specimen was measured and analysed using principal component analysis (PCA) and The invasive potential of the freshwater snail Radix rubiginosa recently introduced into South Africa discriminant functions analysis (DFA). The most useful discriminant conchological characters were shell length, length of the last body whorl and aperture width. Use of these shell characters provided simple yet effective criteria for the separation of R. rubiginosa and L. natalensis. For both size classes R. rubiginosa had larger, more broadly ovate shells with longer (higher) body whorls than either of the two populations of L. natalensis that exhibited smaller, elongated shells with shorter (lower) body whorls. Also, R. rubiginosa had a narrower aperture width compared to the larger, wider aperture of the UKZN Pond L. natalensis population. The Greyville L. natalensis population was found to have narrower apertures than both R. rubiginosa and L. natalensis (UKZN Pond). The morphology of the radula and the reproductive anatomy of R. rubiginosa and L. natalensis from both the UKZN and Greyville Ponds showed little variation. The species did however vary in the relative numbers of radula teeth in each field and this serves as an additional useful diagnostic character. Both L. natalensis populations had similar mantle pigmentation patterns but that of R. rubiginosa was different. The mantle surface of R. rubiginosa was mottled black with patches of pale white to yellow. There were also large unpigmented fields and stripes that were not observed in L. natalensis. Having found characters to conveniently separate the alien R. rubiginosa from the indigenous L. natalensis, it became increasingly important to assess the potential invasiveness of this introduced species and its likely impact. The potential invasiveness of R. rubiginosa was assessed in relation to the already invasive North American Physidae Physa acuta Draparnaud, 1805 and the indigenous L. natalensis. This was particularly important in view of the success of P. acuta as an invader in South Africa. The hatching success, frequency of egg abnormalities, embryonic development, growth, survivorship, fecundity and life history parameters (GRR, Ro, rm, T and λ) for the four snail populations were assessed at three experimental temperatures (20oC, 25oC and 30oC). The invasive potential of the freshwater snail Radix rubiginosa recently introduced into South Africa The results showed that R. rubiginosa and P. acuta had a higher growth coefficient (K), longer survivorship, higher fecundity (higher hatching success, fewer egg abnormalities, longer duration of oviposition), shorter incubation period, greater life history parameters (GRR, Ro, rm and λ) and wider temperature tolerances than the two L. natalensis populations tested. The high adaptability of P. acuta to changing environmental factors such as temperature, is in agreement with the fact that it is now more widespread in South Africa than the indigenous species L. natalensis. This has important implications for R. rubiginosa, since this species displayed reproductive attributes and a temperature tolerance that were similar and in certain cases even exceeded the performance of the invasive P. acuta. This therefore implies that R. rubiginosa has the potential to colonize a wider geographical and altitudinal range than L. natalensis, and perhaps even P. acuta. Also, the superior reproductive ability of R. rubiginosa over L. natalensis is likely to present a situation that allows for its rapid spread as well as a possible impact on the indigenous L. natalensis that might render it vulnerable. / Thesis (Ph.D.)-University of KwaZulu-Natal, Westville, 2011.

No description available.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Os moluscos pateliformes de água doce da região Neotropical são comumente atribuídos a família Ancylidae sensu latum, abrangendo sete gêneros com pelo menos 13 espécies válidas e sete com identificação duvidosa. Os ancilídeos possuem pequenas dimensões, alcançam no máximo 15 mm de comprimento. Sua concha é frágil, composta por duas regiões, a protoconcha e a teleoconcha, as quais apresentam caracteres relevantes para a sistemática. Na parte mole as impressões musculares, a pigmentação do manto, o sistema reprodutor e a rádula são importantes para o estudo da família. Apesar de existirem vários registros de ocorrência para ancílideos no Estado do Rio de Janeiro (ERJ), existem poucos dados morfológicos. O principal objetivo deste estudo foi fornecer e ampliar as informações sobre a morfologia e distribuição geográfica das espécies de Ancylidae encontradas no ERJ. Os materiais utilizados foram procedentes de coletas próprias, material depositado em Coleções Científicas e dados de revisão bibliográfica. O estudo da morfologia comparada das conchas foi realizado com o auxílio de imagens de microscópio óptico e de varredura. Para a comparação das partes moles, os espécimes foram corados e dissecados sob lupa. Através da conquiliometria analisamos as diferenças inter e intrapopulacionais. Com este trabalho, a riqueza conhecida para Ancylidae no ERJ, aumentou de cinco para sete espécies: Burnupia sp., Ferrissia sp., Gundlachia radiata (Guilding, 1828),G. ticaga (Marcus & Marcus, 1962), Gundlachia sp., Hebetancylus moricandi (d`Orbigny, 1837) e Uncancylus concentricus (d`Orbigny, 1837). Gundlachia radiata e U. concentricus constituem novos registros para o ERJ, e G. radiata para a Região Sudeste. As três espécies com o maior número de registros de ocorrência no ERJ foram: G. ticaga (66%), Ferrissia sp. (37%) e Gundlachia sp. (18%). A ampla distribuição de G. ticaga pode ser devido à capacidade de suportar ambientes impactados. Em relação à morfologia, Burnupia sp. difere de Burnupia ingae Lanzer, 1991, única espécie deste gênero descrita para o Brasil, por apresentar diferenças na microescultura da concha e também na forma das impressões musculares. Ferrissia sp. difere de F. gentilis Lanzer, 1991, devido a diferenças na microescultura apical e número de cúspides no dente central da rádula. Gundlachia sp. é diferente de G. ticaga e G. radiata, por apresentar a abertura da concha mais arredondada, ápice mais recurvado, ultrapassando a borda da concha, pontuações irregulares em toda a protoconcha e forma dos músculos adutores anterior direito e posterior mais elíptica. A morfologia interna também mostra diferenças entre Gundlachia sp. e G. ticaga, como o apêndice terminal do útero e o número de folículos do ovoteste. Através das análises conquiliométricas, constatamos para os gêneros Burnupia, Ferrrissia e Gundlachia, que os índices morfométricos se mostraram melhores que as medidas lineares para a discriminação das espécies, provavelmente porque esses índices diminuem o efeito da amplitude de tamanho das conchas, que são fortemente influenciadas pelas variações ecofenotípicas. Contudo, os caracteres diagnósticos das conchas e das partes moles (impressões musculares) são indispensáveis para a identificação dos gêneros e espécies de Ancylidae. Palavras-chave: Mollusca. Moluscos de água doce. Morfologia. Distribuição geográfica. Estado do Rio de Janeiro.uscos. / The pateliform freshwater molluscs of the Neotropical region are commonly attributed to Ancylidae sensu latum, comprising seven genera with at least 13 valid species and seven with dubious identification. Ancylids are small, reaching up to 15 mm length. The shell is fragile, composed of two regions: protoconch and teleoconch, which microsculpture, which is relevant to systematic. In the soft part mantle scars, pigmentation of mantle, radula and reproductive system are important for the study of the family. There are several records of occurrence of ancylids in the State of Rio de Janeiro (SRJ) but few morphological data. The main objective of this study was to provide and expand morphological and geographical information about Ancylidae species found in the SRJ. The materials were come from own collections, material deposited in scientific collections and data for review. A comparative study of shell morphology was carried out by light and scanning microscope images. To compare the soft parts, specimens were stained and dissected under a research stereomicroscope. Interpopulation and intrapopulation variation were studied by shell morphometric analysis. The richness of Ancylidae in SRJ were increased from five to seven species: Burnupia sp., Ferrissia sp., Gundlachia radiata (Guilding, 1828), Gundlachia ticaga (Marcus & Marcus, 1962), Gundlachia sp., Hebetancylus moricandi (d`Orbigny, 1837) e Uncancylus concentricus (d`Orbigny, 1837). Gundlachia radiata and U. concentricus are new records for SRJ, and G. radiata to Southeast Brazil. The most frequent three species in SRJ were: G. ticaga (66%), Ferrissia sp. (37%) and Gundlachia sp. (18%). The wide distribution of G. ticaga may be due to the ability to survive in impacted environments. With respect to morphology, the single Burnupia species described from Brazil, Burnupia ingae Lanzer, 1991, differs from Burnupia sp. in shell microsculpture and also in the shape of muscle scars. Ferrissia sp. differs from F. gentilis Lanzer, 1991, due to differences in apical microsculpture and number of cusps on radula central tooth. Gundlachia sp. is different from G. ticaga and G. radiata, by presenting the shell opening rounder, more curved apex surpassing the edge of the shell, irregular punctuations across whole protoconch and the more elliptic right anterior and posterior adductor muscle scars. The morphology also shows differences between Gundlachia sp. and G. ticaga, as the terminal appendix of the uterus and the number of follicles of ovotestis. Shell morphometric analysis found that the indices provided better discrimination of species than the linear measurements to Burnupia, Ferrrissia and Gundlachia, probably because these indices decrease the effect of the shells size range that are strongly influenced by ecophenotipics variations. However, the diagnostic characters of the shells (microesculpture apical) and soft tissue (muscle scars and mantle pigmentation) are essential to identify genera and species of Ancylidae. Keywords: Mollusca. Freshwater snails. Morphology. Geographic distribution. Rio de Janeiro State. LISTAe pateliform.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Os moluscos pateliformes de água doce da região Neotropical são comumente atribuídos a família Ancylidae sensu latum, abrangendo sete gêneros com pelo menos 13 espécies válidas e sete com identificação duvidosa. Os ancilídeos possuem pequenas dimensões, alcançam no máximo 15 mm de comprimento. Sua concha é frágil, composta por duas regiões, a protoconcha e a teleoconcha, as quais apresentam caracteres relevantes para a sistemática. Na parte mole as impressões musculares, a pigmentação do manto, o sistema reprodutor e a rádula são importantes para o estudo da família. Apesar de existirem vários registros de ocorrência para ancílideos no Estado do Rio de Janeiro (ERJ), existem poucos dados morfológicos. O principal objetivo deste estudo foi fornecer e ampliar as informações sobre a morfologia e distribuição geográfica das espécies de Ancylidae encontradas no ERJ. Os materiais utilizados foram procedentes de coletas próprias, material depositado em Coleções Científicas e dados de revisão bibliográfica. O estudo da morfologia comparada das conchas foi realizado com o auxílio de imagens de microscópio óptico e de varredura. Para a comparação das partes moles, os espécimes foram corados e dissecados sob lupa. Através da conquiliometria analisamos as diferenças inter e intrapopulacionais. Com este trabalho, a riqueza conhecida para Ancylidae no ERJ, aumentou de cinco para sete espécies: Burnupia sp., Ferrissia sp., Gundlachia radiata (Guilding, 1828),G. ticaga (Marcus & Marcus, 1962), Gundlachia sp., Hebetancylus moricandi (d`Orbigny, 1837) e Uncancylus concentricus (d`Orbigny, 1837). Gundlachia radiata e U. concentricus constituem novos registros para o ERJ, e G. radiata para a Região Sudeste. As três espécies com o maior número de registros de ocorrência no ERJ foram: G. ticaga (66%), Ferrissia sp. (37%) e Gundlachia sp. (18%). A ampla distribuição de G. ticaga pode ser devido à capacidade de suportar ambientes impactados. Em relação à morfologia, Burnupia sp. difere de Burnupia ingae Lanzer, 1991, única espécie deste gênero descrita para o Brasil, por apresentar diferenças na microescultura da concha e também na forma das impressões musculares. Ferrissia sp. difere de F. gentilis Lanzer, 1991, devido a diferenças na microescultura apical e número de cúspides no dente central da rádula. Gundlachia sp. é diferente de G. ticaga e G. radiata, por apresentar a abertura da concha mais arredondada, ápice mais recurvado, ultrapassando a borda da concha, pontuações irregulares em toda a protoconcha e forma dos músculos adutores anterior direito e posterior mais elíptica. A morfologia interna também mostra diferenças entre Gundlachia sp. e G. ticaga, como o apêndice terminal do útero e o número de folículos do ovoteste. Através das análises conquiliométricas, constatamos para os gêneros Burnupia, Ferrrissia e Gundlachia, que os índices morfométricos se mostraram melhores que as medidas lineares para a discriminação das espécies, provavelmente porque esses índices diminuem o efeito da amplitude de tamanho das conchas, que são fortemente influenciadas pelas variações ecofenotípicas. Contudo, os caracteres diagnósticos das conchas e das partes moles (impressões musculares) são indispensáveis para a identificação dos gêneros e espécies de Ancylidae. Palavras-chave: Mollusca. Moluscos de água doce. Morfologia. Distribuição geográfica. Estado do Rio de Janeiro.uscos. / The pateliform freshwater molluscs of the Neotropical region are commonly attributed to Ancylidae sensu latum, comprising seven genera with at least 13 valid species and seven with dubious identification. Ancylids are small, reaching up to 15 mm length. The shell is fragile, composed of two regions: protoconch and teleoconch, which microsculpture, which is relevant to systematic. In the soft part mantle scars, pigmentation of mantle, radula and reproductive system are important for the study of the family. There are several records of occurrence of ancylids in the State of Rio de Janeiro (SRJ) but few morphological data. The main objective of this study was to provide and expand morphological and geographical information about Ancylidae species found in the SRJ. The materials were come from own collections, material deposited in scientific collections and data for review. A comparative study of shell morphology was carried out by light and scanning microscope images. To compare the soft parts, specimens were stained and dissected under a research stereomicroscope. Interpopulation and intrapopulation variation were studied by shell morphometric analysis. The richness of Ancylidae in SRJ were increased from five to seven species: Burnupia sp., Ferrissia sp., Gundlachia radiata (Guilding, 1828), Gundlachia ticaga (Marcus & Marcus, 1962), Gundlachia sp., Hebetancylus moricandi (d`Orbigny, 1837) e Uncancylus concentricus (d`Orbigny, 1837). Gundlachia radiata and U. concentricus are new records for SRJ, and G. radiata to Southeast Brazil. The most frequent three species in SRJ were: G. ticaga (66%), Ferrissia sp. (37%) and Gundlachia sp. (18%). The wide distribution of G. ticaga may be due to the ability to survive in impacted environments. With respect to morphology, the single Burnupia species described from Brazil, Burnupia ingae Lanzer, 1991, differs from Burnupia sp. in shell microsculpture and also in the shape of muscle scars. Ferrissia sp. differs from F. gentilis Lanzer, 1991, due to differences in apical microsculpture and number of cusps on radula central tooth. Gundlachia sp. is different from G. ticaga and G. radiata, by presenting the shell opening rounder, more curved apex surpassing the edge of the shell, irregular punctuations across whole protoconch and the more elliptic right anterior and posterior adductor muscle scars. The morphology also shows differences between Gundlachia sp. and G. ticaga, as the terminal appendix of the uterus and the number of follicles of ovotestis. Shell morphometric analysis found that the indices provided better discrimination of species than the linear measurements to Burnupia, Ferrrissia and Gundlachia, probably because these indices decrease the effect of the shells size range that are strongly influenced by ecophenotipics variations. However, the diagnostic characters of the shells (microesculpture apical) and soft tissue (muscle scars and mantle pigmentation) are essential to identify genera and species of Ancylidae. Keywords: Mollusca. Freshwater snails. Morphology. Geographic distribution. Rio de Janeiro State. LISTAe pateliform.

Heavy metal bioaccumulation in aquatic organisms may occur through direct or indirect uptake routes. Research indicates that the significance of uptake route varies with contaminant and organism exposed. The relative importance of different metal sources in aquatic systems was investigated by exposing freshwater snails to dietary or dissolved sources of cadmium. Snails were exposed to control, contaminated food only, contaminated water only, and contaminated food and water treatments. During the 15-day exposure, samples were taken to determine Cd concentration in snail soft tissue, snail shell, algal food, and overlying water. Analyses of snail soft tissue and shells indicate that exposure route significantly affects Cd concentrations in the tissues. In both cases, dissolved Cd is the primary contributor to metal body burden.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-04-01T11:36:22Z No. of bitstreams: 1 thaysdeoliveiradias.pdf: 1461234 bytes, checksum: 9479b441e689c9ee5ebd5d297e617460 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2016-04-24T03:00:22Z (GMT) No. of bitstreams: 1 thaysdeoliveiradias.pdf: 1461234 bytes, checksum: 9479b441e689c9ee5ebd5d297e617460 (MD5) / Made available in DSpace on 2016-04-24T03:00:22Z (GMT). No. of bitstreams: 1 thaysdeoliveiradias.pdf: 1461234 bytes, checksum: 9479b441e689c9ee5ebd5d297e617460 (MD5) Previous issue date: 2013-02-28 / O objetivo deste trabalho foi realizar um levantamento malacológico e investigar a presença, distribuição e avaliar a possibilidade de infecção por Fasciola hepatica em moluscos da espécie Pseudosuccinea columella, em coleções hídricas na microrregião de Juiz de Fora, Minas Gerais, Brasil, nos anos de 2009, 2011 e 2012. O primeiro capítulo apresenta os resultados sobre a composição da malacofauna, com a lista de espécies encontradas e informações sobre a sua distribuição. Foram realizadas coletas em 22 localidades na microrregião de Juiz de Fora, sendo os moluscos coletados através de uma metodologia de coleta direta. Foram encontradas na microrregião de Juiz de Fora 9 espécies de gastrópodes: Melanoides tuberculatus (Müller, 1774) (Thiaridae); Biomphalaria tenagophila (d´Orbigny, 1835); (Planorbidae), Pseudosuccinea columella (Say, 1817) (Lymnaeidae); Stenophysa marmorata (Guilding, 1828), Haitia acuta (Draparnaud, 1805) e Afrophysa brasiliensis (Küster, 1844) (Physiidae); Pomacea sp. (Perry, 1810) (Ampullariidea), Gundlachia sp. (Pfeiffer, 1849) Ancylidae e o pulmonado estilomatóforo Omalonyx sp. (d´Orbigny, 1937) (Succineidae). Um total de 719 moluscos foram coletados, sendo que 29,6% H. acuta, 0,97% S. marmorata, 0,83% A. brasiliensis, 56,8% P. columella, 5,14% B. tenagophila, 5% Gundlachia sp., 0,13% Melanoides tuberculatus e 1,39% Pomacea sp. Dentre estas, quatro são espécies exóticas: M. tuberculatus, P. columella, S. marmorata e H. acuta. No segundo capítulo é registrada a ocorrência de S. marmorata e A. brasiliensis no município de Juiz de Fora, com informações sobre a distribuição e um estudo morfológico detalhado das espécies. O terceiro capítulo apresenta o estudo que teve por finalidade investigar a presença e distribuição e avaliar a possibilidade de infecção por F. hepatica em moluscos da espécie P. columella. As coletas foram realizadas em 22 ecossistemas aquáticos lóticos e lênticos. Foram coletados 409 espécimes em 04 dos 22 pontos de coleta que incluíram córregos, represas, lagos, lagoas e valas de irrigação. O estudo morfológico dos espécimes permitiu a identificação específica P. columella. A pesquisa por formas larvais de trematódeos foi realizada através da técnica de exposição à luz artificial. Nenhum molusco examinado estava infectado. A ocorrência da fasciolose está ligada à presença de moluscos do gênero Lymnaea, neste sentido, é de extrema importância a realização de estudos com o objetivo de monitorar as diferentes regiões do Brasil, onde haja a presença de hospedeiros intermediários e, consequentemente, o potencial para a instalação da doença. O presente trabalho constitui o primeiro estudo sobre a composição da malacofauna límnica na microrregião de Juiz de Fora, Minas Gerais. O levantamento da malacofauna límnica da região é de fundamental importância para o maior conhecimento da ocorrência e distribuição das espécies nativas, além do reconhecimento da presença e distribuição de espécies exóticas e hospedeiras de helmintos, servindo de ponto inicial para o desenvolvimento de estratégias de controle. / The aim of this study was to realize a malacological survey and to investigate the presence, distribution of Fasciola hepatica so as to evaluate the presence of infected individuals of Pseudosuccinea columella in water collections at the micro region of Juiz de Fora, Minas Gerais, Brazil, in the years 2009, 2011 and 2012. In the first chapter, results of species composition are presented, with a list of these species and information about its distribution. The collections were made in 22 localities, being the snails collected by direct collections. It were found 9 gastropod species in Juiz de Fora microregion: Melanoides tuberculatus (Müller, 1774) (Thiaridae); Biomphalaria tenagophila (d´Orbigny, 1835); (Planorbidae), Pseudosuccinea columella (Say, 1817) (Lymnaeidae); Stenophysa marmorata (Guilding, 1828), Haitia acuta (Draparnaud, 1805) e Afrophysa brasiliensis (Küster, 1844) (Physiidae); Pomacea sp. (Perry, 1810) (Ampullariidea), Gundlachia sp. (Pfeiffer, 1849) Ancylidae and the pulmonate stylommatophora Omalonyx sp. (d´Orbigny, 1937) (Succineidae). It were collected 719 snails, being 29,6% H. acuta, 0,97% S. marmorata, 0,83% A. brasiliensis, 56,8% P. columella, 5,14% B. tenagophila, 5% Gundlachia sp., 0,13% Melanoides tuberculatus and 1,39% Pomacea sp. Among these, four are alien species: M. tuberculatus, P. columella, S. marmorata and H. acuta. In the second chapter it was registered the occurrence of S. marmorata and A. brasiliensis in Juiz de Fora, with information on distribution and a detailed morphological study of the species. The third chapter presents a study that aimed to investigate the presence, distribution and to evaluate the possibility of infection by F. hepatica in the freshwater snail P. columella. The collections were realized in 22 in lotic and lentic aquatic ecossystems. It were collected 409 specimens in 04 of 22 collections points that comprised streams, dams, lakes, lagoons and irrigation ditches. The morphological studies of specimens allowed the identification of P. columella. The research of larval forms of trematodes was realized by exposure to artificial light. No infected snails were found. The occurrence of fasciolosis is related to the presence of snails of the genus Lymnaea, in this way, it is important to realize studies in order to monitoring different regions of Brazil were intermediate hosts are found, that are potential areas to the establishment of the disease. The present study is the first study of freshwater malacological composition in the microregion of Juiz de Fora, Minas Gerais. The survey of this fauna in this region is of fundamental importance to the knowledge of occurrence and distribution of native species, besides the recognition of the presence and distribution of native and alien species and helminth hosts, serving as threshold for the development of control strategies.