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Evolution of time-control mechanisms in subterranean organisms: cave fishes under light-dark cycles (Teleostei: Siluriformes, Characiformes)

Trajano, Eleonora; Ueno, J. C. H.; Barreto, Luiz Silveira Menna
Fonte: Taylor & Francis LTD; Abingdon Publicador: Taylor & Francis LTD; Abingdon
Tipo: Artigo de Revista Científica
ENG
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Subterranean organisms are excellent models for chronobiological studies, yet relatively few taxa have been investigated with this focus. Former results were interpreted as a pattern of regression of circadian locomotor activity rhythms in troglobitic (exclusively subterranean) species. In this paper we report results of experiments with cave fishes showing variable degrees of troglomorphism (reduction of eyes, melanic pigmentation and other specializations related to the hypogean life) submitted to light-dark cycles, preceded and followed by several days in constant darkness. Samples from seven species have been monitored in our laboratory for the detection of significant circadian rhythms in locomotor activity: S. typhlops, an extremely troglomophic species, presented the lowest number of significant components in the circadian range (only one individual out of eight in DD1 and three other fish in LD), all weak (low values of spectral power). Higher incidence of circadian components was observed for P. kronei - only one among six studied catfish without significant circadian rhythms under DD1 and DD2; spectral powers were generally high. Intermediate situations were observed for the remaining species, however all of them presented relatively strong significant rhythms under LD. Residual oscillations (circadian rhythms in DD2) were detected in at least part of the studied individuals of all species but S. typhlops...

"PCBs e pesticidas organoclorados em tecidos de peixes da Baixada Santista, São Paulo"; PCBS and Organochlorides Pesticides in fishes of Santos Bay, São Paulo, Brazil

Magalhães, Caio Augusto
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 02/02/2006 PT
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Este trabalho visou determinar a ocorrência de PCBs e pesticidas organoclorados em peixes da região da Baixada Santista. Foram feitas coletas de peixes das espécies Paralonchurus brasiliensis, Trichiurus lepturus e Cathorops spixii em três diferentes localidades. Depois de sub-amostradas em músculo, fígado, brânquias e gônadas, as amostras foram extraídas em aparelhagem Soxhlet e analisadas por técnicas cromatográficas. O DDT apresentou-se em 66 % das amostras com concentrações variando entre 18,92 e 690,29 ng.g-1 lipídio. O HCH foi detectado em 34 % das amostras com concentração variando de 8,92 a 103,04 ng.g-1 lipídio, sendo a região da Ilha da Moela a mais afetada por esse composto. O Mirex apresentou-se em 28 % das amostras e alcançou valores entre 5,90 e 222,17 ng.g-1 lipídio. O HCB foi o inseticida menos encontrado neste trabalho, com 16 % das amostras apresentando contaminação variando de 7,75 a 94,47 ng.g-1 lipídio, todas na espécie bentônica Cathorops spixii. Os PCBs estiveram presentes em todas as localidades analisadas, sendo os congêneres com número entre quatro e sete cloros os que mais bioacumularam. A bioacumulação de organoclorados nos diferentes tecidos não ocorreu de forma igual para todas as espécies analisadas. Aparentemente...

O HIPERBENTOS NA ALIMENTAÇÃO DE ESPÉCIES DE PEIXES JOVENS, DA REGIÃO ESTUARINA-LAGUNAR DE CANANÉIA (25 º02´S - 47º 56´ W) SÃO PAULO.; The hyperbenthos on the diet of jovenile fishes of Cananeia lagoon estuarine region (25º 02º´S 47º 56´W) São Paulo.

Ribeiro, Maria Aparecida Guimaraes
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 11/09/1995 PT
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Os objetivos do presente trabalho foram: estudar a estrutura, a distribuição e a variação sazonal da fauna hiperbêntica e simultaneamente avaliar os padrões de utilização do hiperbentos pelas espécies de peixes (jovens) e entender qual a importância da comunidade hiperbêntica na trofodinâmica da região estuarino-Iagunar de Cananéia. As coletas foram realizadas mensalmente com um "refro beam-trawl" modificado para o hiperbentos, tarrafa e rede de espera para os peixes, durante o período de outubro/83 a setembro/84 , em quatro locais do sublitoral (Arrozal, Batata I , Trincheira e Cardoso). As comunidades de peixes e de hiperbentos não mostraram padrões de distribuição espacial distintos nas quatro localidades. Tanto a comunidade de peixes como a hiperbêntica apresentaram variações sazonais com algumas diferenças; os peixes atingiram sua abundância máxima na primavera, 28,260/0-, no verão 24,26%, no outono 27,38% e no inverno 19,58%. A comunidade hiperbêntica variou de 30,04% na primavera, 19,81% no verão, 23,78% no outono e 26,37% no inverno; a riqueza específica e a abundância foram praticamente constantes durante o período de estudo e a estação mais rica foi a primavera. Os taxa do hiperbentos mais abundantes foram: Mysidacea...

The goatfish Pseudupeneus maculatus and its follower fishes at an oceanic island in the tropical west Atlantic

Sazima, C.; Krajewski, J. P.; Bonaldo, R. M.; Guimaraes, P. R.
Fonte: Blackwell Publishing Publicador: Blackwell Publishing
Tipo: Artigo de Revista Científica Formato: 883-891
ENG
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The influence of a substratum-disturbing forager, the spotted goatfish Pseudupeneus maculatus on the assemblage of its escorting, opportunistic-feeding fishes was examined at Fernando de Noronha Archipelago (tropical west Atlantic). Followers attracted to spotted goatfish foraging singly differed from followers of spotted goatfish foraging in groups in several characteristics. The larger the nuclear fish group, the greater the species richness and number of individuals of followers. Moreover, groups of foraging spotted goatfish attracted herbivores, not recorded for spotted goatfish foraging singly. The size of follower individuals increased with the size and the number of foraging spotted goatfish. The zoobenthivorous habits of the spotted goatfish and its ability to disturb a variety of soft substrata render it an important nuclear fish for several follower species of the reef fish assemblage at Fernando de Noronha. (c) 2006 the Authors Journal compilation (c) 2006 the Fisheries Society of the British Isles.

Carbon sources and trophic position of the main species of fishes of Baía River, Paraná River floodplain, Brazil

Manetta, G. I.; Benedito-Cecilio, E.; Martinelli, M.
Fonte: Instituto Internacional de Ecologia Publicador: Instituto Internacional de Ecologia
Tipo: Artigo de Revista Científica Formato: 283-290
ENG
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Com o objetivo de verificar a fonte de carbono e a posição trófica das principais espécies de peixe da planície de inundação do rio Paraná, foram analisadas as proporções de isótopos estáveis de carbono (delta13C) e nitrogênio (delta15N) em músculos de peixes amostrados no período de chuvas. Foram analisados indivíduos adultos das espécies Loricariichthys platymetopon, Schizodon borellii, Leporinus lacustris, Auchenipterus osteomystax, Iheringichthys labrosus, Leporinus friderici e Serrasalmus marginatus. e dados foram comparados com os resultados da análise do conteúdo estomacal. Os produtores primários existentes no subsistema Baía foram as plantas C3 (vegetação ripária, macrófitas, perifíton e fitoplâncton) e as plantas C4 (macrófitas). O resultado da análise de contribuição revelou que o carbono utilizado pelas espécies foi proveniente das plantas C3. Conforme as estimativas da posição trófica (dieta e delta15N), as espécies foram categorizadas como consumidoras primárias (Loricariichthys platymetopon, Schizodon borellii, Leporinus lacustris e Leporinus friderici) e consumidoras secundárias (Auchenipterus osteomystax, Iheringichthys labrosus e Serrasalmus marginatus). Não houve diferença significativa entre os dois métodos utilizados.; In order to verify the carbon source and trophic position of the main species of fishes...

Tectonic history and the biogeography of the freshwater fishes from the coastal drainages of eastern Brazil: an example of faunal evolution associated with a divergent continental margin

Ribeiro, Alexandre Cunha
Fonte: Sociedade Brasileira de Ictiologia Publicador: Sociedade Brasileira de Ictiologia
Tipo: Artigo de Revista Científica Formato: 225-246
ENG
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As drenagens costeiras do leste do Brasil correspondem a áreas de grande significado biogeográfico, apresentando um alto grau de endemismo em sua fauna de peixes. Padrões filogenéticos sugerem uma relação próxima entre os rios que correm para o Atlântico a os adjacentes das terras altas do escudo cristalino. Entretanto, pouco tem sido dito sobre a dinâmica dos processos geológicos relacionados aos eventos cladogenéticos entre estas áreas. Padrões de distribuição e filogenéticos sugerem uma íntima associação com a história geológica da margem continental passiva da América do Sul, desde o Cretáceo aos dias atuais. Soerguimentos macrodômicos, rifteamento, movimentos verticais entre blocos falhados e o recuo erosivo da margem leste sul-americana são considerados como as principais forças geológicas atuando sobre a distribuição da ictiofauna de água doce nestas áreas. A atividade tectônica associada à ruptura do Gondwana e separação da América do Sul e África criou seis megadomos que são responsáveis por configurar a maior parte do atual curso das principais bacias hidrográficas do escudo cristalino. Com exceção das bacias localizadas às margens de tais megadomos, estes rios desenvolveram longos e sinuosos circuitos sobre o antigo escudo cristalino brasileiro antes de desaguarem no então recentemente aberto Oceano Atlântico. Eventos cladogenéticos iniciais entre drenagens de terras altas do escudo cristalino e tributários do Atlântico podem estar associados com processos vicariantes desta fase inicial...

Effects of acute heat exposure on respiratory metabolism and blood glucose in freshwater fishes, Prochilodus scrofa (curimbatá) and Cyprinus carpio (carp) acclimatized to tropical winter

Zuim, S.M.Fontes; Macari, Marcos
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 287-289
ENG
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1. 1. Routine oxygen consumption and blood glucose were determined from freshwater fishes, Prochilodus scrofa and Cyprinus carpio, exposed at high temperatures for 1 hr. 2. 2. Prochilodus scrofa had a significantly higher rate of oxygen consumption at 30°C than at 25°C, and carp higher at 25°C than at 30°C. 3. 3. Blood glucose was significantly higher for Cyprinus carpio than for Prochilodus scrofa at 25 and 30°C; however, after exposure to these temperatures for 1 hr blood glucose did not change significantly for both species. 4. 4. The results suggest that these interspecific variations may be linked to the differences between native and foreign fishes and their way of life. © 1985.

Marine Fishes of the Azores : annotated checklist and bibliography : a catalogue of the Azorean marine ichthyodiversity

Santos, Ricardo S.; Porteiro, Filipe M.; Barreiros, João P.
Fonte: Universidade dos Açores Publicador: Universidade dos Açores
Tipo: Livro
Publicado em //1997 ENG
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A list of the marine fishes of the Azores is presented. The list is based on a review of the literature combined with an examination of selected specimens available from collections of Azorean fishes deposited in museums, including the collection of fish at the Department of Oceanography and Fisheries of the University of the Azores (Horta). Personal information collected over several years is also incorporated. The geographic area considered is the Economic Exclusive Zone of the Azores. The list is organised in Classes, Orders and Families according to Nelson (1994). The scientific names are, for the most part, those used in Fishes of the North-eastern Atlantic and the Mediterranean (FNAM) (Whitehead et al. 1989), and they are organised in alphabetical order within the families. Clofnam numbers (see Hureau & Monod 1979) are included for reference. Information is given if the species is not cited for the Azores in FNAM. Vernacular names are always both presented in Portuguese (Azorean names) and English. Synonyms, misspellings and misidentifications found in the literature in reference to the occurrence of species in the Azores are also quoted. The 460 species listed, belong to 142 families; 12 species are cited for the first time for the Azores. Details are given for 23 other species cited for the first time for the Azores in the Red Book of Portuguese Vertebrates (ICN 1993). Fifty-four ambiguous and/or exceptional occurrences are included in an appendix. A second appendix contains the remaining corrections to the checklist of fish included in ICN (1993). The paper concludes with a synthesis and an annotated indexed bibliography of the marine fishes of the Azores. Most references are available through the library of the Department of Oceanography and Fisheries of the University of the Azores.

Feeding biology of a guild of benthivorous fishes in a sandy shore on south-eastern Brazilian coast

ZAHORCSAK,P.; SILVANO,R. A. M.; SAZIMA,I.
Fonte: Instituto Internacional de Ecologia Publicador: Instituto Internacional de Ecologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/08/2000 EN
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The feeding biology of eight species of benthivorous fishes was studied in a sandy shore at Anchieta Island, south-eastern Brazilian coast. The fishes fed mainly on Amphipoda and Mysidacea crustaceans. The diet of the most abundant species, the drum Umbrina coroides, was analyzed in three standard length classes (20-55, 56-90 and 91-135 mm). This sciaenid showed an ontogenetic diet shift from Mysidacea to Amphipoda. The feeding behaviour of the sciaenid U. coroides and the gerreid Eucinostomus gula was recorded while snorkeling. During their foraging both species uncovered small organisms buried in the sand. Notwithstanding general similarities in diet, U. coroides and E. gula presented differences in feeding behaviour and morphology. Two carangid species of the genus Trachinotus differed in diet composition and consumed a larger array of food items than the remaining fish species. Differences in diet and feeding activity between the remaining benthivorous species were noted. These differences possibly reduce overlap in resource use and favour the coexistence of guilds of benthivorous fishes on sandy shores.

Saccocoelioides godoyi n.sp. (Haploporidae) and other trematodes parasites of fishes from the Guaiba estuary, RS, Brazil

Kohn,Anna; Fróes,Oscar Miranda
Fonte: Instituto Oswaldo Cruz, Ministério da Saúde Publicador: Instituto Oswaldo Cruz, Ministério da Saúde
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/1986 EN
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One hundred and fourteen specimens of eleven different species of freshwater fishes from the Guaiba estuary, were examined for digenetic flukes. Saccocoelioides godoyi n.sp. proposed herein, is closest to S. magniovatus and to S. szidati; S. magniovatus is much smaller with comparably larger eggs and S. szidati has larger hermaphroditic sac and considerably larger testis. Creptotrema creptotrema is referred to a new host; Acanthostomum gnerii, Crepidostomum platense, Eocreadium intermedium (immature form), Parspina argentinensis and Zonocotyle bicaecata are reported. This paper confirms the similatary between the parasites of freshwater fishes from Argentina and Brazil. Measurements and original figures of all species are given.

Digenea and acanthocephala of elasmobranch fishes from the southern coast of Brazil

Knoff,Marcelo; São Clemente,Sérgio Carmona de; Pinto,Roberto Magalhães; Gomes,Delir Corrêa
Fonte: Instituto Oswaldo Cruz, Ministério da Saúde Publicador: Instituto Oswaldo Cruz, Ministério da Saúde
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/11/2001 EN
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New records for helminth species recovered from elasmobranch fishes in Brazil are established. Digenean and acanthocephalan parasites of elasmobranch fishes are reported from the southern coast of Brazil: Otodistomum veliporum (Creplin, 1837) Stafford, 1904 (Digenea: Azygiidae) in the stomach and spiral valve of Dipturus trachydermus and in the spiral valve of Squatina sp. Cystacanths and juveniles of the acanthocephalans Corynosoma australe Johnston, 1937 and Corynosoma sp., in the spiral valve of Squatina sp., Galeorhinus galeus and Hexanchus griseus and in the stomach of Squalus megalops; a juvenile of Gorgorhynchus sp., in the spiral valve of Sphyrna zygaena. Dipturus trachydermus and Squatina sp. are new host records for O. veliporum. Digeneans and acanthocephalans are reported for the first time parasitizing elasmobranch fishes in Brazil.

Habitat preferences of common native fishes in a tropical river in Southeastern Brazil

Costa,Marcus Rodrigues da; Mattos,Tailan Moretti; Borges,Joyce Liz; Araújo,Francisco Gerson
Fonte: Sociedade Brasileira de Ictiologia Publicador: Sociedade Brasileira de Ictiologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2013 EN
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We determined in this study the habitat preferences of seven native fish species in a regulated river in Southeastern Brazil. We tested the hypothesis that fishes differ in habitat preference and that they use stretches of the river differing in hydraulic characteristics and substrate type. We surveyed fishes in four 1-km long river stretches encompassing different habitat traits, where we also measured water depth, velocity, and substrate type. We investigated preference patterns of four Siluriformes (Loricariichthys castaneus, Hoplosternum littorale, Pimelodus maculatus, and Trachelyopterus striatulus) and three Characiformes (Astyanax aff. bimaculatus, Oligosarcus hepsetus, and Hoplias malabaricus), representing approximately 70% of the total number of fishes and 64% of the total biomass. We classified fishes into four habitat guilds: (1) a slow-flowing water guild that occupied mud-sand substrate, composed of two Siluriformes in either shallow (< 4 m, i.e., H. littorale) or deep (> 8 m, L. castaneus) waters; (2) a run-dwelling guild that occurs in deep backwaters with clay-mud substrate, composed of the Characiformes A. aff. bimaculatus and O. hepsetus; (3) a run-dwelling guild that occurs in sandy and shallow substrate, composed of T. striatulus; and (4) a fast-flowing guild that occurs primarily along shorelines with shallow mud bottoms...

Fish Community Responses to the Combined Effects of Decreased Hydroperiod and Nonnative Fish Invasions in a Karst Wetland: Are Everglades Solution Holes Sinks for Native Fishes?

Rehage, Jennifer S.; Liston, S. E.; Dunker, K. J.; Loftus, W. F.
Fonte: FIU Digital Commons Publicador: FIU Digital Commons
Tipo: Artigo de Revista Científica
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Short-hydroperiod Everglades wetlands have been disproportionately affected by reductions in freshwater inflows, land conversion and biotic invasions. Severe hydroperiod reductions in these habitats, including the Rocky Glades, coupled with proximity to canals that act as sources of invasions, may limit their ability to support high levels of aquatic production. We examined whether karst solution holes function as dry-down refuges for fishes, providing a source of marsh colonists upon reflooding, by tracking fish abundance, nonnative composition, and survival in solution holes throughout the dry season. We paired field surveys with an in situ nonnative predation experiment that tested the effects of predation by the recent invader, African jewelfish (Hemichromis letourneuxi) on native fishes. Over the 3 years surveyed, a large number of the solution holes dried before the onset of the wet season, while those retaining water had low survivorship and were dominated by nonnatives. In the experiment, mortality of eastern mosquitofish (Gambusia holbrooki) in the presence of African jewelfish was greater than that associated with deteriorating water quality. Under current water management, findings suggest that solution holes are largely sinks for native fishes...

Fish Community Responses to the Combined Effects of Decreased Hydroperiod and Nonnative Fish Invasions in a Karst Wetland: Are Everglades Solution Holes Sinks for Native Fishes?

Rehage, Jennifer S.; Liston, S. E.; Dunker, K. J.; Loftus, W. F.
Fonte: FIU Digital Commons Publicador: FIU Digital Commons
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
36.94%
Short-hydroperiod Everglades wetlands have been disproportionately affected by reductions in freshwater inflows, land conversion and biotic invasions. Severe hydroperiod reductions in these habitats, including the Rocky Glades, coupled with proximity to canals that act as sources of invasions, may limit their ability to support high levels of aquatic production. We examined whether karst solution holes function as dry-down refuges for fishes, providing a source of marsh colonists upon reflooding, by tracking fish abundance, nonnative composition, and survival in solution holes throughout the dry season. We paired field surveys with an in situ nonnative predation experiment that tested the effects of predation by the recent invader, African jewelfish (Hemichromis letourneuxi) on native fishes. Over the 3 years surveyed, a large number of the solution holes dried before the onset of the wet season, while those retaining water had low survivorship and were dominated by nonnatives. In the experiment, mortality of eastern mosquitofish (Gambusia holbrooki) in the presence of African jewelfish was greater than that associated with deteriorating water quality. Under current water management, findings suggest that solution holes are largely sinks for native fishes...

A molecular genetic appraisal of biodiversity and conservation units in freshwater fishes from southern Australia.

Hammer, Michael P.
Fonte: Universidade de Adelaide Publicador: Universidade de Adelaide
Tipo: Tese de Doutorado
Publicado em //2008
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The freshwater fish fauna of southern Australia is characterised by low species richness and high endemism in groups displaying southern temperate, temperate-subtropical or temperate-tropical distributions. Comparatively few studies in Australia have incorporated modern molecular techniques to delineate species boundaries and define within-species conservation units. This is problematic because freshwater fishes are likely to show high levels of cryptic speciation and marked spatial sub-structure, and is information which is needed to conserve biological diversity and maintain the integrity of ecological communities and processes. The current study uses a ‘combined evidence’ approach, led principally by a set of nuclear genetic markers (allozymes), to assess species boundaries, spatial sub-structure and conservation units in obligate freshwater fishes from southern Australia. A literature review (Chapter 2) concerns the nature and effects of fragmentation in freshwater environments. It considers the implications for freshwater fishes and the types of extrinsic and intrinsic characteristics, both natural and human accelerated, that might drive population fragmentation and divergence. This theoretical framework is then applied to a suite of six largely co-occurring species groups with contrasting biological characteristics...

Influência da composição de substrato do recife na atividade e distribuição de peixes zoobentívoros no arquipélago de Fernando de Noronha, Pernambuco; The influence of substratum composition on the activity and distribution of benthic carnivorous reef fishes of the Fernando de Noronha Archipelago

João Paulo Krajewski
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 02/07/2010 PT
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Os recifes proporcionam abrigo e alimento para diversas espécies de peixes e, portanto, pode haver uma relação entre a distribuição e comportamento de peixes recifais e a composição de substratos do recife. Fatores físicos, especialmente o hidrodinamismo e profundidade, também parecem ter grande influência sobre a distribuição e comportamento de algumas espécies de peixes recifais. No presente estudo a relação entre a distribuição e atividade de espécies de peixes, especialmente as que se alimentam de invertebrados bentônicos (zoobentivoras), e a composição de substratos do recife, hidrodinamismo e profundidade foi estudada em recifes do arquipélago de Fernando de Noronha, Pernambuco. As principais espécies zoobentivoras de Fernando de Noronha forrageiam principalmente sobre substratos compostos por algas filamentosas verdes e vermelhas e algas pardas cobertas de sedimento, e sua atividade alimentar não é distribuída proporcionalmente à abundância relativa dos diferentes substratos. Ainda, para algumas espécies, o uso de substrato pode variar entre recifes. A dieta principal dos zoobentívoros mais abundantes em Fernando de Noronha são poliquetas e crustáceos. Quatro espécies foram estudadas quanto à variação de sua atividade entre diferentes recifes. Haemulon chrysargyreum...

Relaciones tróficas y parasitismo en peces marinos: uso de cestodes Trypanorhyncha como marcadores biológicos; Trophic relationships and parasitism in marine fishes: use of Trypanorhyncha cestodes as biological tags

Menoret, Adriana
Fonte: Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires Publicador: Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires
Tipo: info:eu-repo/semantics/doctoralThesis; tesis doctoral; info:eu-repo/semantics/publishedVersion Formato: application/pdf
Publicado em //2012 SPA
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Los cestodes Trypanorhyncha son parásitos con ciclos de vida complejos en los que intervienen varios hospedadores. Las larvas infectan invertebrados y peces teleósteos (hospedadores intermediarios y/o paraténicos) y los adultos se desarrollan en elasmobranquios (hospedador definitivo). La transmisión de los tripanorrincos se produce entre los hospedadores, a través de la red trófica. Dado que estos cestodes presentan ciertas características morfológicas y ecológicas tienen el potencial de ser utilizados como marcadores biológicos de sus hospedadores. El objetivo principal fue realizar la revisión taxonómica de cestodes tripanorrincos en el Mar Argentino y evaluar su potencialidad como marcadores biológicos a partir de la (1) la estimación de la diversidad de tripanorrincos en el área de estudio mediante la descripción de nuevos taxa y la verificación de la identidad de las epecies de tripanorrincos previamente registradas en el área, (2) la caracterización de los ciclos de vida de los especímenes coleccionados y el rol que desempeñan los peces en su transmisión, (3) la evaluación del grado de especificidad de los estadios de cestodes, (4) la reconstrucción de las tramas tróficas de los peces involucrados en los ciclos de vida...

Body fineness ratio as a predictor of maximum prolonged-swimming speed in coral reef fishes

Walker, Jeffrey A.; Alfaro, Michael E.; Noble, Mae M.; Fulton, Christopher J.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica Formato: 13 pages
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The ability to sustain high swimming speeds is believed to be an important factor affecting resource acquisition in fishes. While we have gained insights into how fin morphology and motion influences swimming performance in coral reef fishes, the role of other traits, such as body shape, remains poorly understood. We explore the ability of two mechanistic models of the causal relationship between body fineness ratio and endurance swimming-performance to predict maximum prolonged-swimming speed (Umax ) among 84 fish species from the Great Barrier Reef, Australia. A drag model, based on semi-empirical data on the drag of rigid, submerged bodies of revolution, was applied to species that employ pectoral-fin propulsion with a rigid body at U max. An alternative model, based on the results of computer simulations of optimal shape in self-propelled undulating bodies, was applied to the species that swim by body-caudal-fin propulsion at Umax . For pectoral-fin swimmers, Umax increased with fineness, and the rate of increase decreased with fineness, as predicted by the drag model. While the mechanistic and statistical models of the relationship between fineness and Umax were very similar, the mechanistic (and statistical) model explained only a small fraction of the variance in Umax . For body-caudal-fin swimmers...

Helminth parasites of atherinopsid freshwater fishes (Osteichthyes: Atheriniformes) from central Mexico

Lira-Guerrero,Georgina; García-Prieto,Luis; Pérez-Ponce de León,Gerardo
Fonte: Instituto de Biología Publicador: Instituto de Biología
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2008 EN
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Between May 1997 and September 1998, 270 atherinopsids belonging to 7 fish species were analyzed for helminths in 6 lakes located in central Mexico. In addition, a database with all the available previous records of helminth parasites of atherinopsids was built. Based on both information sources, we analyze the composition of the helminth fauna parasitizing atherinopsid freshwater fishes from central Mexico, in order to determine some general species compositional patterns. The helminth fauna parasitizing this fish family in central Mexico is composed by 10 digeneans, 13 cestodes, 1 acanthocephalan, and 8 nematodes (24 of them as larval stage). Individual species richness ranged from 1 to 22 helminth species. Feeding habits of the hosts are identified as the main factor in determining helminth species composition (22 of them are acquired through ingestion). Helminth species composition of almost all host species was dominated by generalist helminth species. Only 2 specialist species were found: Allocreadium mexicanum and Spinitectus osorioi, representing the core helminth fauna of this group of fishes. These results corroborate the hypothesis that the parasite fauna in freshwater fishes is largely circumscribed by higher levels of monophyletic host taxa.

Spatial partitioning of Fishes in the río Paraguay, Paraguay

CHERNOFF,BARRY; WILLINK,PHILIP W; MACHADO-ALLISON,ANTONIO
Fonte: ASOCIACIÓN INTERCIENCIA Publicador: ASOCIACIÓN INTERCIENCIA
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2004 EN
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The 173 species of freshwater fishes collected during the AquaRAP expedition to the Río Paraguay were analyzed to determine if distributional patterns existed within the region. The region was divided into five subregions and into eight macrohabitats. Two null hypotheses were tested and rejected: i) that fishes are randomly distributed with respect to subregion, and ii) that fishes are randomly distributed with respect to macrohabitat. The results show a strong subregional effect, such that two distributional elements were present. One consists of an association between the Río Paraguay and Río Negro subregions. The other consists of Río Apa and Riacho La Paz subregions. The analysis of distributions with respect to macrohabitats also reveals two components. The first relates the beach and main channel faunas to the macrohabitats that are inundated during seasonal flooding, such as flooded forests and lagoons. The assemblage associated with the flooding cycle accounts for more than 75% of the fishes collected. The second component comprises habitats found within Río Apa and Riacho La Paz (e.g. clear water, rapids, etc.). This component has a relatively sharp boundary with respect to Río Paraguay, with more than a 50% turnover in fauna. These results show that core conservation areas must be set up within situations in which the seasonal flooding cycle is unimpeded and the area of inundation is relatively unmodified. Also...