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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
61

New Records of Marine Tardigrades From Moorea, French Polynesia, With the Description of Styraconyx Turbinarium sp. nov. (Arthrotardigrada, Halechiniscidae)

Bartels, Paul J., Fontoura, Paulo, Nelson, Diane R. 01 January 2015 (has links)
Five marine arthrotardigrade species are recorded from Moorea, Society Islands, French Polynesia. Four were collected from coral sand; two, Dipodarctus anaholiensis Pollock, 1995 and Florarctus kwoni Chang & Rho, 1997, are new records for the region, and two, Halechiniscus perfectus Schulz, 1955 and Styraconyx kristenseni kristenseni Renaud-Mornant, 1981, have been previously reported. The fifth, a new species Styraconyx turbinarium sp. nov., is described and was collected from the drifting brown alga Turbinaria ornata. The new species is characterized by the presence of peduncles on all digits, an elongate primary clava, and the lateral cirrus A arising from a common pedestal and enveloped by a common membrane extending almost to the claval tip. The new species differs from the most similar species, Styraconyx tyrrhenus D'Addabbo Gallo, Morone De Lucia & de Zio Grimaldi, 1989, by having longer and differently shaped primary clavae which are elongated in the new species and club-shaped in S. tyrrhenus. By having a dorsal cuticle that is coarsely punctated but without folds or other ornamentations, the new species can be easily distinguished from S. craticulus (Pollock, 1983), a species with similar primary clavae, but with cuticular dorsal folds ornamented with a grid-like pattern.
62

Aquatic tardigrades in the Great Smoky Mountains National Park, North Carolina and Tennessee, U.S.A., with the description of a new species of Thulinius (Tardigrada, Isohypsibiidae)

Bertolani, Roberto, Bartels, Paul J., Guidetti, Roberto, Cesari, Michele, Nelson, Diane R. 13 February 2014 (has links)
As part of the All Taxa Biodiversity Inventory (http://www.dlia.org), an extensive survey of tardigrades has been conducted in the Great Smoky Mountains National Park (GSMNP) in Tennessee and North Carolina, U.S.A., by Bartels and Nelson. Freshwater tardigrades include three species in the aquatic genus Thulinius (Eutardigrada, Isohypsibiidae). A new species, Thulinius romanoi, described from stream sediment, is distinguished from all other congeners by having a sculptured cuticle. In addition, the presence of Thulinius augusti (Murray, 1907) was verified by combined morphological and molecular analysis, and nine specimens of a third species, Thulinius cf. saltursus, were also found. Thulinius augusti is a new record for the United States. Thulinius saltursus (Schuster, Toftner & Grigarick, 1978) was previously recorded in California and Ohio, but our specimens vary slightly in morphology. The list of tardigrades from streams in the GSMNP was updated to a total of 44 species, 22 of which were predominantly or exclusively aquatic.
63

A Large-Scale, Multihabitat Inventory of the Phylum Tardigrada in the Great Smoky Mountains National Park, USA: A Preliminary Report

Bartels, Paul, Nelson, Diane R. 01 March 2006 (has links)
An All Taxa Biodiversity Inventory (ATBI) is underway in the Great Smoky Mountains National Park (GSMNP), with the goal of attempting to identify all species of life in the 2000 km2 park. The GSMNP is a hotbed of biodiversity, a U.N. Biosphere Reserve, and one of the largest protected, deciduous forests in the temperate world. We have completed two field seasons of work on the tardigrades in the park (2001-2002). As of July 2003, we have collected 420 samples from soil/decomposed leaf litter, lichens and mosses on trees, and stream sediment and periphyton. A few samples from caves, bird nests, and lichens/mosses on rocks were also collected. Samples were taken from within permanent plots established for the ATBI, representing the major biological communities of the GSMNP. Tardigrades were extracted from samples using centrifugation with Ludox AM™, individually mounted on microscope slides in Hoyer's medium, and studied with phase contrast and DIC microscopy. We have examined 1524 slides from 60 samples as of July 2003. Prior to our work, only three species of tardigrades had been previously reported from a few samples in the park. We have now recorded 42 species, 8 of which we believe may be new to science. Species richness estimates were calculated using EstimateS 6 software for each of the major tardigrade habitats. Overall, we predict that there are 47 to 76 species in the GSMNP, with generally similar species richness in soil, lichen, moss, and stream habitats. Species richness estimates were also used to determine that the number of tardigrade species was greater in mosses at breast height on trees than in mosses at the base of trees.
64

Marine Tardigrades of the Bahamas With the Description of Two New Species and Updated Keys to the Species of Anisonyches and Archechiniscus

Bartels, Paul J., Fontoura, Paulo, Nelson, Diane R. 20 May 2018 (has links)
This is the first survey of subtidal marine tardigrades from the Bahamas, and we compare our results with earlier studies of Bahamian intertidal habitats. In 2011 and 2014 we collected 60 subtidal sand samples from Bimini, the Berry Islands, New Providence, Eleuthera, and the Exumas. We found 11 species only one of which, Dipodarctus subterraneus (Renaud- Debyser, 1959), had been found in the previous intertidal Bahamian collections. Thus, 10 species are new records for the Bahamas, and four of these are new to science. We describe two of the new species (Archechiniscus bahamensis sp. nov. and Anisonyches eleutherensis sp. nov.). Additional material is needed for a conclusive identification of the undescribed species of Batillipes and Florarctus. Based on examination of the holotype of Anisonyches diakidius Pollock, 1975, we redescribe this species and give an emended diagnosis of the genus and the species. We also provide new keys to the spe-cies in the genera Archechiniscus and Anisonyches. A Chao2 species richness estimate indicated that our sampling effort was extensive and probably recovered most common species. Correlations of abundance and diversity indices with regard to depth, distance to nearest shore, and sediment grain size were not significant.
65

Dispersal in free-living, marine, benthic nematodes : passive or active processes?

Ullberg, Jörgen January 2004 (has links)
<p>Meiofauna, and especially marine nematodes are common in sediments around the world. Despite very wide ranging distributions in many nematode species, little is presently known about their dispersal mechanisms shaping these patterns. Rafting, and perhaps ballast water transport has been suggested as viable means for nematode long-range transport. On a much smaller scale other processes have been suggested for their dispersal. They generally include some form of passive suspension into the water column and later on a passive, haphazard settling back towards the bottom.</p><p>Small-scale phenomena in nematode dispersal were studied by conducting a series of studies at Askö field station, Trosa Archipelago, Baltic proper. Studied aspects were one case of macrofaunal influence on nematode dispersal rate, using an amphipod, <i>Monoporeia affinis</i> as disturbing agent, and three different studies on mechanisms related to settling. The experiments were conducted both in laboratory and field settings.</p><p>The amphipod <i>Monoporeia affinis</i> did not exert any influence on the dispersal rate in the nematodes. The nematode dispersal was only an effect of time, in the aspect that the more time that past, the more nematodes dispersed from their place of origin. The settling experiments revealed that nematodes do have an active component in their settling behaviour, as they were able to exert influence on the spot where they were to settle. They were able to choose settling spot in response to the food quality of the sediment. It also became evident that contrary to common belief, nematodes are able to extend their presence in the water column far beyond the times that would be predicted considering settling velocities and hydrodynamic conditions alone.</p>
66

Dispersal in free-living, marine, benthic nematodes : passive or active processes?

Ullberg, Jörgen January 2004 (has links)
Meiofauna, and especially marine nematodes are common in sediments around the world. Despite very wide ranging distributions in many nematode species, little is presently known about their dispersal mechanisms shaping these patterns. Rafting, and perhaps ballast water transport has been suggested as viable means for nematode long-range transport. On a much smaller scale other processes have been suggested for their dispersal. They generally include some form of passive suspension into the water column and later on a passive, haphazard settling back towards the bottom. Small-scale phenomena in nematode dispersal were studied by conducting a series of studies at Askö field station, Trosa Archipelago, Baltic proper. Studied aspects were one case of macrofaunal influence on nematode dispersal rate, using an amphipod, Monoporeia affinis as disturbing agent, and three different studies on mechanisms related to settling. The experiments were conducted both in laboratory and field settings. The amphipod Monoporeia affinis did not exert any influence on the dispersal rate in the nematodes. The nematode dispersal was only an effect of time, in the aspect that the more time that past, the more nematodes dispersed from their place of origin. The settling experiments revealed that nematodes do have an active component in their settling behaviour, as they were able to exert influence on the spot where they were to settle. They were able to choose settling spot in response to the food quality of the sediment. It also became evident that contrary to common belief, nematodes are able to extend their presence in the water column far beyond the times that would be predicted considering settling velocities and hydrodynamic conditions alone.
67

Cultivo em Massa do Copépodo Bentônico Tisbe biminiensis (Harpacticoida) e Sua Utilização na Larvicultura do Camarão Macrobrachium rosenbergii (Palaemonidae).

Christine Bezerra Ribeiro, Aurelyanna January 2005 (has links)
Made available in DSpace on 2014-06-12T15:05:32Z (GMT). No. of bitstreams: 2 arquivo1797_1.pdf: 494985 bytes, checksum: 49085c55ca04e2212bd3d03cd5d25893 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2005 / Este trabalho teve como objetivos desenvolver técnicas de cultivo em massa do copépodo Tisbe biminiensis em volumes de 5 litros e avaliar o seu desempenho como substituto da Artemia na larvicultura do camarão Macrobrachium rosenbergii. O cultivo do copépodo foi realizado em caixas plásticas (32 x 47 x 14,5 cm) munidas de aeração, com 5 litros de água do mar filtrada, sob temperatura ambiente e salinidade de 35°/oo. O alimento fornecido diariamente foi ração para peixes de aquário e a cada dois dias, nas trocas de água, 500ml das diatomáceas Phaeodactylum tricornutum ou Thalassiosira fluviatilis. Em todos os experimentos o número de copépodos foi estimado por subamostragem. O teste de desempenho do copépodo na larvicultura do M. rosenbergii foi realizado com quatro réplicas para cada um dos cinco tratamentos: 0, 25, 50, 75 e 100% de introdução de copépodo. Os resultados obtidos demonstraram que a coleta semanal de prole e a presença de sedimento arenoso não afetaram o crescimento dos copépodos. Os testes de sustentabilidade dos cultivos demonstraram que T. biminiensis cresceu bem em laboratório mantendo altas densidades por períodos de até 130 dias. O sistema de cultivo produziu uma média de 28.000indivíduos/l/dia A população de copépodos se recuperou 4 dias após a retirada da prole. A substituição da Artemia pelo T. biminiensis não foi favorável a M. rosenbergii, porém as altas mortalidades observadas no controle indicam algum tipo de problema no sistema de cultivo que pode ter influenciado os resultados
68

Distribuição espaço-temporal da meiofauna associada a algas epilíticas em costão rochoso, com ênfase aos Nematoda livres (Arraial do Cabo - Rio de Janeiro, Brasil)

Monteiro Lage, Luciana January 2005 (has links)
Made available in DSpace on 2014-06-12T15:05:45Z (GMT). No. of bitstreams: 2 arquivo1816_1.pdf: 970414 bytes, checksum: c46045e757ee01c0c23ab3cebc57c4ab (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2005 / Em costões rochosos a comunidade de algas epilíticas constitue um importante local de refúgio e de procriação para a fauna associada, além de sustentarem uma alta produção primária. A exposição a ondas afeta indiretamente a meiofauna, por influenciar a distribuição vertical e a biomassa dos habitats algais. Dentre os grupos da meiofauna, os Nematoda destacam-se como os invertebrados de maior abundância e riqueza de espécies. Os Nematoda livres apresentam ampla distribuição horizontal e vertical na escala global, distribuindo-se desde a região litoral até grandes profundidades oceânicas e em todas as latitudes. No presente estudo a composição e a abundância da meiofauna em função de faixas de profundidade, assim como dos gêneros da nematofauna são investigados no sentido de responder se existe, para essas faixas, diferenças sazonais bem marcadas. Na região de Arraial do Cabo ocorre, principalmente nos períodos de primavera e verão, o fenômeno da ressurgência, que faz com que a região sustente uma alta produtividade. Foram coletadas amostras de algas epilíticas no costão da Pedra Vermelha nas 4 estação do ano e em três faixas de profundidades (0-2m, 2-5m e 5-8m). No costão do sonar as amostragens foram feitas no verão e no inverno em duas profundidades (0-2m e 2-5m). A meiofauna foi contada e identificada ao nível de grandes grupos e de cada amostra foram separados 30 Nematoda para a montagem de lâminas permanentes e identificação ao nível de gênero. Tanto a meiofauna quanto a nematofauna apresentaram padrões de estratificação espacial bem marcados. O padrão sazonal também foi evidente nos dois costões, sendo mais efetivo no Sonar do que na Pedra Vermelha. Para a nematofauna foram registradas 5 novas ocorrências para o Brasil e 38 para o Rio de Janeiro. O gênero Draconema apresentou duas novas espécies, cujas diferenças morfofisiológicas foram comparadas às sete espécies conhecidas atualmente. Muito embora o método de amostragem empregado no presente estudo não pemitiu quantificar a meiofauna e esclarecer qualquer processo ecológico, dados qualitativos relevantes foram aqui pontuados em relação à distribuição espaço-temporal da nematofauna em costões rochosos
69

Ecologia e taxonomia da associação de Copepoda Harpacticoida no talude da Bacia de Campos , RJ, Brasil

Pereira Wandeness, Adriane 31 January 2009 (has links)
Made available in DSpace on 2014-06-12T22:57:29Z (GMT). No. of bitstreams: 2 arquivo1412_1.pdf: 6537585 bytes, checksum: 2cac5088c7c91e2dd804758a99640811 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2009 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / A taxonomia e a ecologia dos Copepoda Harpacticoida dos sedimentos do talude da Bacia de Campos são aqui apresentadas (capitulo 1), assim como a descrição de três espécies novas de Echinopsyllus (capitulo 2) e uma discussão acerca da distribuição geográfica e batimétrica da família Ancorabolidae (capitulo 3). Um total de 44 estações foi amostrado ao longo de nove transectos, considerando-se cinco profundidades (750 m, 1050 m, 1350 m, 1650 m e 1950 m) nas áreas Norte e Sul da Bacia de Campos e em dois estratos sedimentares (0-2 e 2-5cm). Para analisar a composição taxonômica e os aspectos ecológicos dos dados, foram construídos gráficos e organizadas tabelas. O índice de diversidade utilizado foi o de Shannon-Wiener e a equitabilidade calculada pelo índice de Pielou (J ). A análise de variância, por postos, de Kruskal-Wallis, foi aplicada aos valores do número total de indivíduos de Copepoda Harpacticoida, por amostra, a fim de testar diferenças entre os estratos trabalhados. Para a determinação de padrões ecológicos da comunidade, aplicou-se o índice de similaridade de Bray-Curtis e foi realizada uma análise de ordenação não-métrica multidimensional, considerando diferentes fatores: campanhas, áreas, profundidades e estratos. A significância da formação dos grupos de amostras foi testada pela análise ANOSIM. Para uma avaliação das relações entre a estrutura da comunidade de Harpacticoida e as variáveis ambientais, foi realizada a análise BIOENV. Foram identificados 1449 exemplares de Copepoda Harpacticoida. A composição desta fauna, na Bacia de Campos, mostrou-se semelhante à de outras áreas, especialmente, a da Bacia de Angola; porém, um alto valor percentual de táxons novos foi encontrado na Bacia de Campos (10 gêneros e 78 espécies novas). Os valores de densidade foram inferiores, de um modo geral, aos de outros estudos de mar profundo. A diversidade apresentou, em geral, valores altos ao longo das diferentes estações e áreas estudadas, além de uma tendência à redução com o aumento da profundidade. O estrato mais superficial apresentou, significativamente, os maiores valores de densidade e diversidade, o que confirma os relatos já existentes na literatura, Utilizando diferentes níveis de resolução taxonômica, os padrões observados para a comunidade mostraram uma resposta semelhante, no entanto, o uso de categorias taxonômicas mais elevadas leva a uma grande perda do conhecimento da biodiversidade marinha. A descoberta de novas espécies de Echinopsyllus estendeu o limite de distribuição desse gênero para o hemisfério sul e é uma evidência adicional de uma ampla distribuição dos gêneros de Ancorabolidae, anteriormente não esperada, nos oceanos mundiais. A posição filogené tica de Echinopsyllus dentro de Ancorabolinae é discutida. As observações dos registros de latitudes, profundidades e faixas de temperatura dos ancorabolídeos evidenc iaram uma clara tendência de distribuição: das altas latitudes existem registros em profundidades baixas e altas, enquanto nas baixas latitudes, os registros provém, unicamente, de altas profundidades. Esse padrão nos leva a hipotetizar que os limites de distribuição latitudinal e batimétrica das espécies de Ancorabolidae podem ser controlados/restritos pela temperatura. A posição filogené tica basal da subfamilia Laophontodinae sugere que Ancorabolidae foi, originalmente, uma família de áreas rasas e plataformas continentais frias de águas subantarticas que irradiaram para o mar profundo
70

Structure and functioning of the benthic communities in the extreme dynamic intertidal mudflats along the Guianas coasts : trophic fate of the infauna / Structure et fonctionnement des communautés benthiques des vasières intertidales hautement instables des côtes guyanaises : leur devenir dans le réseau trophique

Nguyen, Thanh Hien 13 February 2018 (has links)
Entre les fleuves Amazone et Orénoque, la frange côtière atlantique de l’Amérique du Sud (1500 km) est considérée comme la plus vaseuse au monde, conséquence des apports de sédiments en suspension de l’Amazone. Malgré la forte variabilité et l’instabilité de ces vasières uniques au monde, elles apparaissent comme des écosystèmes très productifs et sont des habitats clés dans l’accomplissement du cycle de vie des espèces de poissons et d’oiseaux qui les exploitent. Cependant, les connaissances sur les communautés biologiques qui y sont associées restent au niveau exploratoire. Ce travail de thèse vise donc à décrire la structure de l’endofaune benthique intertidale des vasières guyanaises et à définir son fonctionnement dans des environnements vaseux tropicaux très instables. Comme prévu, la forte instabilité des sédiments a entraîné une très faible diversité des assemblages de la macrofaune et de la méiofaune. Néanmoins, les communautés benthiques des vasières guyanaises ont montré une abondance remarquablement élevée avec la dominance d'espèces opportunistes de petites tailles. 39 taxons de la macrofaune ont été trouvés tandis que la méiofaune était moins diversifiée avec la présence de 34 taxons. Le tanaidacée Halmyrapseudes spaansi et le polychète Sigambra grubii sont les deux espèces de macrofaune les plus abondantes, largement réparties le long de la côte guyanaise. De même, le nématode Pseudochromadora spp., suceur d’épistrate, et Halomonhystera sp. 1 (non deposit feeders) étaient les deux espèces de méiofaune les plus abondantes sur chacune des stations. La distribution des communautés benthiques sont spécifiques aux sites d’étude et varie saisonnièrement. Les assemblages en zone estuarienne (Sinnamary) étaient plus diversifiées que dans la zone de vasière nue (Awala), alors que les abondances des communautés benthiques étaient toujours plus élevées en saison humide qu’en saison sèche. Les facteurs abiotiques et biotiques ont influencé significativement les communautés benthiques. Néanmoins, les changements dans la structure de la communauté benthique induits par la disponibilité des sources alimentaires (chl a) et la pression de prédation étaient tout aussi importantes que les variations des assemblages imposées par les paramètres abiotiques (teneur en eau, salinité ...). En particulier, une forte corrélation a été trouvée entre la méiofaune et le microphytobenthos. Les mesures isotopiques de différents compartiments des vasières ont non seulement révélé le rôle central du microphytobenthos dans la composition du régime alimentaire de la méiofaune, mais ont également montré l'importance écologique de la méiofaune comme principale source de nourriture pour les petits oiseaux limicoles et les poissons côtiers. La méiofaune et le microphytobenthos rentrent dans le régime alimentaire de trois poissons côtiers en grande proportion, alors que les oiseaux limicoles migrateurs présentaient une plus grande diversité de proies. Cependant, la contribution relative des tanaidacées dans le régime alimentaire des oiseaux limicoles était étonnamment faible. Le travail de thèse a permis d'améliorer notre compréhension de la structure de l’endofaune benthique intertidale des vasières guyanaises et de définir son fonctionnement dans des environnements vaseux tropicaux très instables. Ce travail a permis de construire, pour la première fois, un modèle conceptuel de réseau trophique des vasières intertidales mobiles guyanaises. / Locating between the Amazon and Orinoco Rivers, the 1500 km-long Atlantic coastline of South America are considered as the muddiest areas in the world due to the large discharge of suspended sediment from the Amazon. Despite the extreme morphodynamics of these ecosystems, the Guianas mudflats are important feeding zones for many shorebirds and fish. However, the state of knowledge on benthic organisms associated with these highly unstable environments is still at an exploratory stage. This study, therefore, aims to describe the structure and dynamics of the intertidal benthic infauna in the Guianas mudflats and to define its functioning in such highly unstable tropical muddy environments. As expected, the high instability of the sediment resulted in very low diversity of both macrofauna and meiofauna assemblages. Nonetheless, the infauna communities of the Guianas mudflats showed remarkably high abundance with the predominance of small-sized opportunistic species. A total of 39 operational taxonomic units of macrofauna was recorded while meiofauna was less diverse with the occurrence of 34 taxa. The tanaid Halmyrapseudes spaansi and the polychaeta Sigambra grubii are the two most abundant macrofauna species, which widely distributed along the Guianas coast. Likewise, the nematodes epistrate feeder Pseudochromadora spp. and non-deposit feeders Halomonhystera sp. 1 were the principal components of meiofauna communities in every station. The distribution patterns of the infauna were both site-specific and seasonal variation. The assemblages in estuarine habitat were more diverse than in the bare mudflat habitat, while infauna abundances in the WS were always higher than in the DS. Both abiotic and biotic factors significantly influenced the benthic communities. Nevertheless, the changes in benthic community structure induced by food source availability (chl a) and predation pressure were more prominent than the assemblage variations imposed by abiotic parameters (mud content, salinity…). Particularly, the tight coupling between meiofauna and MPB was observed in both distribution patterns and trophic structures. The isotopic measurements of different intertidal compartments not only revealed the pivotal role of MPB on structuring meiofaunal coummunities, but also indicated the ecological importance of meiofauna as the main food source for the small shorebirds and coastal fish. Meiofauna and MPB entered the diet of three coastal fish in great proportion, whereas the migrating shorebirds showed a wider diet breadth. The isotopic ratios were perfectly matched with the feeding guilds assigned by morphological features. However, the relative contribution of tanaids to the top epibenthic predators were surprisingly lower than expected. The thesis has increased our understanding of the Guianas infauna communities, and revealed for the first time a conceptual food web model of these unique intertidal mudflats.

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