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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.
131

The effects of isolation and environmental heterogeneity on intraspecific variation in Calamoecia clitellata, a salt lake-inhabiting copepod

Whitehead, Ayesha L. January 2006 (has links)
[Truncated abstract] This study focussed on how isolation and environmental heterogeneity in salt lakes has influenced intraspecific variation in the calanoid copepod Calamoecia clitellata. Calamoecia clitellata relies on passive vectors for dispersal, and this, coupled with the insular nature of salt lakes, may promote genetic divergence at a molecular level. When contrasting environments are involved, genetic divergence may also occur at the life history level, possibly due to local adaptation. I examined the distribution of genetic variation among 14 populations in Western Australia using molecular genetic markers, and examined variation in life history traits among contrasting environments. To ascertain how isolation had influenced molecular genetic variation, I determined population genetic structure and used a phylogeographic approach to infer the impact of historical events. Environmentally induced variation was also evident in the field, with a switch from subitaneous egg production to resting egg production coinciding with changing environmental conditions. It is proposed that plasticity in life history traits has evolved in response to temporal environmental heterogeneity … It can be concluded that isolation in salt lakes in Western Australia has influenced molecular and phenotypic variation in C. clitellata in contrasting ways. At the molecular level, contemporary and historical isolation have promoted genetic divergence of populations, yet when coupled with environmental heterogeneity, marked phenotype plasticity has arisen. This study raises questions as to whether phenotype plasticity is a widespread phenomena in zooplankton found in temporary saline waters and an adaptive strategy to tolerate marked temporal environmental heterogeneity
132

Estudos ecotoxicológicos com as espécies Argyrodiaptomus furcatus e Notodiaptomus iheringi (Copepoda, Calanoida) / Ecotoxicological studies with the species Argyrodiaptomus furcatus and Notodiaptomus iheringi (Copepoda, Calanoida)

Denise Tieme Okumura 04 February 2011 (has links)
Os Copepoda constituem a maior classe de pequenos crustáceos, com mais de 8.500 espécies descritas. Dentre as cinco ordens de Copepoda de vida livre, as espécies pertencentes à ordem Calanoida apresentam um forte endemismo, com uma restrita distribuição geográfica. Além disso, os Copepoda Calanoida são particularmente sensíveis a contaminantes contidos na coluna de água devido ao seu hábito planctônico. No presente trabalho foram realizados estudos ecotoxicológicos com duas espécies de Copepoda Calanoida, particularmente com as espécies Argyrodiaptomus furcatus Sars, 1901 e Notodiaptomus iheringi Wright, 1935. Estas espécies foram comparadas com relação à sensibilidade e desempenho como organismos-teste na avaliação da qualidade da água em ecossistemas de água doce. Foram testadas e adaptadas metodologias de cultivo em laboratório, e foram estudados os principais aspectos da biologia destes em condições ambientais controladas. Além disso, foram analisados aspectos referentes à dinâmica populacional. A sensibilidade das duas espécies de Calanoida às substâncias de referência sódio, potássio e zinco na forma de cloreto (\'NA\'CL\', \'K\'CL\' e \'ZN\'CL IND.2\', respectivamente), ao dicromato de potássio (\'K IND.2\'CR IND.2\'O IND.7\') e ao sulfato de alumínio (\'AL IND.2\'(\'SO IND.4\')IND.3\'), aos surfactantes dodecilsulfato de sódio (\'C IND.12\'H IND.25\'NA\'O IND.4\'S\') e ácido dodecil benzenosulfonato de sódio (\'CH IND.3\'(\'CH IND.2\')IND.11\'C IND.6\'H IND.4\'S\'O IND.3\'NA\'), foram avaliadas. Além disso, avaliou-se a toxicidade aguda de diferentes amostras ambientais e das toxinas da cianobactéria Microcystis aeruginosa após tratamento por irradiação. Os resultados dos testes ecotoxicológicos foram expressos em concentração efetiva (CE(I)50). Para o cálculo estatístico da CE50 foi utilizado o programa Trimmed Spearman-Karber. Os resultados relativos ao ciclo de vida mostraram que N. iheringi tem um menor tempo de desenvolvimento do que A. furcatus, com tempos de duração do desenvolvimento do ovo determinados pelos métodos indireto e direto. Verificou-se que a espécie de N. iheringi, de menor tamanho, apresentou tempo de desenvolvimento pós-embrionário menor do que a espécie de maior tamanho, A. furcatus. As taxas intrínsecas de crescimento populacional foram mais elevadas para a espécie A. furcatus do que para N. iheringi. Pelos resultados obtidos observou-se que N. iheringi além de atingir tamanhos menores, possui um desenvolvimento mais rápido e ciclo de vida mais curto. Em relação à sensibilidade destes Copepoda Calanoida às substâncias tóxicas observou-se que em relação aos sais, estas duas espécies foram mais sensíveis ao cloreto de potássio (\'K\'CL\'). Em relação aos metais, o grau de toxicidade aos Copepoda decresceu na sequência zinco > cromo > alumínio. Já com em relação aos surfactantes, a espécie N. iheringi foi mais sensível do que A. furcatus, e a toxicidade diminui à medida que o estágio de desenvolvimento dos indivíduos se torna mais avançado. Os náuplios são mais sensíveis à maioria das substâncias de referência testadas (sais, surfactantes, cromo e zinco) do que os estágios de desenvolvimento mais avançados. A espécie N. iheringi é mais sensível aos diversos agentes tóxicos do que a espécie A. furcatus, no entanto, N. iheringi foi mais resistente às cianotoxinas do que A. furcatus. Os resultados apresentados corroboram a idéia de que os calanoides A. furcatus e N. iheringi apresentam elevada sensibilidade a uma variedade de substâncias tóxicas de referência, o que torna viável sua utilização como organismos-teste em ensaios ecotoxicológicos. Estes estudos podem proporcionar maior entendimento sobre a estrutura das comunidades aquáticas e das alterações na dinâmica das populações, no sentido de se poder verificar como as espécies respondem às alterações na qualidade da água e o porquê das modificações na estrutura das comunidades, permitindo, dessa forma, ações de manejo e de conservação visando a preservação da biodiversidade das águas doces. / Copepods constitute the largest class of small crustaceans, with more than 8,500 described species. Among the five orders of free-living copepods, the species belonging to the order Calanoida show strong endemism, with a restricted geographic distribution. Additionally, they are particularly sensitive to contaminants in the water column due to their planktonic habit. In the present study ecotoxicological studies with two species of Calanoida copepods were performed, particularly with the species Argyrodiaptomus furcatus Sars, 1901 and Notodiaptomus iheringi Wright, 1935. These species were compared for sensitivity and performance as test organisms in assessing water quality in freshwater ecosystems. Methods of cultivation in the laboratory were tested and adapted, and the main aspects of these species biology were studied under controlled temperature and photoperiod. In addition, aspects related to population dynamics were also analyzed. The sensitivity of the calanoids to a number of reference substances as: sodium, potassium and zinc in the form of chlorides (\'NA\'CL\', \'K\'CL\' and \'ZN\'CL IND.2\', respectively), potassium dichromate (\'K IND.2\'CR IND.2\'O IND.7\') and aluminum sulfate (\'AL IND.2\'(\'SO IND.4\')IND.3\'), and to the surfactant sodium dodecyl sulfate (\'C IND.12\'H IND.25\'NA\'O IND.4\'S\') and sodium dodecyl benzenesulphonate (\'CH IND.3\'(\'CH IND.2\')IND.11\'C IND.6\'H IND.4\'SO IND.3\'NA\') were evaluated. Also the toxicity of environmental samples and of the cyanobacteria Microcystis aeruginosa toxin after irradiation treatment was tested. The results of ecotoxicity tests were expressed as effective concentrations (EC(I)50). The statistical calculation of the EC50 was carried out by the Trimmed Spearman-Karber program. The results regarding the copepods life cycle showed that N. iheringi has a shorter development time and duration of egg development, by both indirect and direct methods, than A. furcatus. It was found that small sized N. iheringi, had a post-embryonic development faster than the larger species, A. furcatus. The intrinsic rates of population increase were higher for the species A. furcatus than for N. iheringi. The results indicated that N. iheringi besides reaching smaller sizes, has a faster development and shorter life cycle. Regarding the sensitivity of these two species to toxic substances it was observed that in relation to the salts the calanoids were more sensitive to the potassium chloride (\'K\'CL\'). Compared to metals, toxicity to copepods followed the sequence zinc> chromium> aluminum. However, regarding surfactants the species N. iheringi was more sensitive than A. furcatus, and toxicity decreased with the advance in developmental stages. The nauplii were more sensitive to most of the reference substances tested (salts, surfactants, chromium and zinc) than the more advanced developmental stages. The species N. iheringi was more sensitive to various toxic agents than A. furcatus, but N. iheringi was more resistant to the cyanotoxins than A. furcatus. The results support the hypothesis that the calanoid copepods A. furcatus and N. iheringi have high sensitivity to a variety of toxic reference substances, what makes them feasible to be used as test organisms in ecotoxicological tests. The study performed may provide further understanding about the structure of aquatic communities and changes in population dynamics, contributing for the understanding of how species respond to changes in water quality by changes in community structure, subsidizing management actions aiming the conservation of freshwater biodiversity.
133

Diversidade zooplanctônica e variáveis limnológicas das regiões limnética e litorânea de cinco lagoas do Vale do Rio Doce - MG, e suas relações com o entorno / Zooplankton diversity and limnological variables in the limnetica and littoral regions of five lakes in Rio Doce Valley - MG, and the relationship with the surrounding basin

Evandro Mateus Moretto 22 June 2001 (has links)
Nos sistemas lacustres, ocorrem diferenças naturais entre os compartimentos limnético e litorâneo num mesmo lago (hábitats, recurso trófico, ciclos biogeoquímicos e processos hidrológicos) e entre lagos que se encontram em regiões de diferentes coberturas vegetais. Tais diferenças podem determinar variações na diversidade zooplanctônica e nas características químicas e físicas da água. Pelo presente trabalho objetivou-se verificar a ocorrência destas diferenças entre as regiões limnética e litorânea de cinco lagoas (Carioca, Aguapé, Águas Claras, Ariranha e Amarela)pertencentes ao sistema de lagos do Vale do Rio Doce (MG), além de uma comparação destes resultados com os diferentes tipos de vegetação que ocorrem no entorno.Situado a sudoeste do estado de Minas Gerais, o sistema de lagos do Vale do Rio Doce é composto, principalmente, por dois tipos de vegetação terrestre: a floresta secundária de Mata Atlântica que está restrita ao Parque Estadual do Rio Doce; e o cultivo de eucalipto que ocupa grande área da região. As lagoas abordadas no presente estudo foram reunidas em três grupos distintos, segundo o tipo de vegetação que ocorre no seu entorno: lagoa Carioca (floresta de Mata Atlântica); lagoas Aguapé e Águas Claras (cultivo de eucalipto com manejo mais intensivo e com freqüente retirada de espécies nativas do sub-bosque); e lagoas Ariranha e Amarela (cultivo de eucalipto com presença de sub-bosque de espécies nativas da Mata Atlântica). Foram realizadas amostragens nos períodos climáticos de inverno de 1999 (estiagem) e verão de 2000 (chuvas), para as variáveis físicas e químicas da água e para a comunidade zooplanctônica. Pelos resultados obtidos, ficaram claras as diferenças entre os compartimentos limnético e litorâneo em função das variáveis físicas e químicas no período de inverno de 1999, e em função da riqueza de espécies zooplanctônicas em ambos os períodos climáticos estudados. A principal diferença da riqueza de espécies entre os compartimentos foi devida ao maior número de táxons na região litorânea, em função da ocorrência de espécies da família Chydoridae e Macrothricidae (Cladocera), e da família Lecanidae (Rotifera). Por outro lado, não ficaram evidentes as diferenças entre os grupos de lagoas segundo a vegetação do entorno, em função das variáveis limnológicas e dos indicadores de diversidade. Ainda assim, é importante destacar as diferenças entre a lagoa Carioca para as demais lagoas, principalmente, em relação ao seu maior grau de trofia e menor disponibilidade de habitats litorâneos, que determinam uma menor riqueza de espécies. Assim, na lagoa Carioca não ocorreram organismos filtradores e herbívoros pertencentes aos Cladocera, com exceção da espécie Diaphanosona birgei . Foi possível verificar também que as espécies de Copepoda Cyclopoida Thermocyclops minutus e Tropocyclops prasinus ocuparam preferencialmente as regiões limnéticas das lagoas, enquanto que Mesocyclops brasilianus ocorreu de forma mais marcante na litorânea. De forma geral, foi possível verificar que os tipos de vegetação não determinaram diferenças nas condições limnológicas e na diversidade zooplanctônica, uma vez que não se observaram padrões semelhantes nos valores das variáveis analisadas dentro de cada grupo de lagoas. / In lacustrine systems there are natural differences among the limnetic and littoral region in the same lake (habitat, food resources, biogeochemical cycles and hydrological processes) as well as between lakes that are located in regions with different vegetation cover. Such differences can determine defferences in the physical and chemical characteristics of the water as well as in the zooplankton diversity. The present work had the objective of verify the existence of these differences among limnetic and littoral region of five lakes (Carioca, Aguapé, Águas Claras, Ariranha e Amarela) belonging to the ake system of Rio Doce Valley (MG), and to analyse these results regarding the different vegetation cover existing in the lake surroundings. Located at the Southeast of Minas Gerais State, the Rio Doce Valley Lake System is covered by two main types of vegetation: secondary atlantic forest, restricted to the area of the State Park of Rio Doce, and Eucalyptus plantation covering the largest portion of the region. The lakes analysed in the present study were grouped in three distinct categories, according to the type of plant coverage in the surroundings: lake Carioca (atlantic forest); lakes Aguapé and Águas Claras ( Eucalyptus, without native forest layer) and lakes Ariranha and Amarela (mixed formation of Eucalyptus and native forest species). Samplig was carried out in the winter (dry period) of 1999 and summer (wet period) of 2000, for both physical and chemical water analysis and zooplankton community studies. There were clear differences among limnetic and littoral regions, regarding physical and chemical characteristics in the winter, and regarding zooplankton richness in both, dry and wet seasons. Major differences in species richness among these compartments were determined by the large number of taxa found in the littoral region, particularly due to the occurrence of species of Chydoridae and Macrothricidae (Cladocera) and Lecanidae (Rotifera). On the other hand, differences among the groups of lakes, according to the type of plant cover around the lake, were not evident, considering the limnological variables and diversity indices. There were, nevertheless, differences between Lake Carioca and the other lakes, mainly related to its higher trophic state, which combined with a small littoral development determines a low zooplankton species richness. Thus, in Lake Carioca filter-feeding Cladocera does not occur, except for Diaphanosoma birgei. It was also possible to verify that the species of Copepoda Cyclopoida Thermocyclops minutus, and Tropocyclops prasinus preferentiatly occupied the limnetic region of the lakes, whereas Mesocyclops brasilianus had a marked occurrence in the littoral region. In general, it was possible to conclude that the type of plant covering did not influence limnological conditions and zooplankton diversity since it was not possible to find a pattern regarding the variables here analysed, if considering those group of lakes.
134

Food Quality Effects on Zooplankton Growth and Energy Transfer in Pelagic Freshwater Food Webs / Effekter av födokvalitet på djurplanktons tillväxt och på energiöverföringen i födovävar i sjöar

Persson, Jonas January 2007 (has links)
Poor food quality can have large negative effects on zooplankton growth and this can also affect food web interactions. The main aims of this thesis were to study the importance of different food quality aspects in Daphnia, to identify potentially important differences among zooplankton taxa, and to put food quality research into a natural context by identifying the importance of food quality and quantity in lakes of different nutrient content. In the first experiment, the RNA:DNA ratio was positively related to the somatic growth rate of Daphnia, supporting a connection between P content, RNA content, and growth rate. The second experiment showed that EPA was important for Daphnia somatic growth, and 0.9 µg EPA mg C-1 was identified as the threshold below which negative effects on Daphnia growth occurred. A field survey identified patterns in the PUFA content of zooplankton that could be explained by taxonomy and trophic position. Cladocera enriched EPA and ARA relative to seston, and Copepoda primarily enriched DHA. In a whole-lake experiment, gentle fertilization of an oligotrophicated reservoir increased the seston P content and the biomass of high quality phytoplankton (Cryptophyceae, high EPA content). This was followed by increases in zooplankton and fish biomasses. An empirical model based on data from a literature survey predicted that food quantity is most important for zooplankton growth in oligotrophic lakes, and that food quality factors are more important in eutrophic lakes. Thus, zooplankton growth, and energy transfer efficiency in the food web, is predicted to be highest in mesotrophic lakes. The results predict that the strength and nature of food quantity and quality limitation of Daphnia growth varies with lake trophic state, and that some combination of food quantity and/or quality limitation should be expected in nearly all lakes.
135

A Comparative Anatomical and Phylogenetic Approach to Nervous System Evolution in Arthropods

Andrew, David R. January 2012 (has links)
Arthropods are the most species-rich group of animals, and as such they exhibit an amazing diversity of morphological, behavioral, and ecological adaptations. Because of this diversity, the evolutionary history of this group has been, and still is notoriously difficult to determine because considerations of different traits invariably support alternative evolutionary relationships. Their nervous systems provide an invaluable set of characters for systematic inferences about the origins and evolutionary trajectories of Arthropoda. This is because nervous systems are ubiquitous and contain a wealth of structures from which to infer shared ancestry. Considerations of ancestral arthropod relationships have further provided insights into how arthropod nervous systems have maintained some traits through evolutionary time and how others have been modified or acquired as novelties. This dissertation explores the evolution of arthropod brains within an interdisciplinary framework, utilizing comparative neuroanatomical, neural cladistic, and molecular phylogenetic analyses to support novel hypotheses of nervous system evolution in arthropods. The field of neurophylogenetics relies on the characterization of shared derived neural traits to infer ancestry amongst taxa. The first portion of this work describes highly conserved neural elements from the lamina, or first optic neuropil, of several crustaceans. This study is followed by a neural cladistic study that infers evolutionary relationships amongst major arthropod groups based solely on neural traits. The results of this study are then compared to those from a large-scale molecular phylogenomic analysis of hundreds of conserved orthologous genes. Results from neural cladistic and molecular phylogenetics suggest several species whose neuroanatomical characterization would provide support for novel evolutionary hypotheses. The last portion of this dissertation details a comparative neuroanatomical study on one such diagnostic taxa, the copepod Tigriopus californicus. Two principles of arthropod nervous system organization and evolution are repeatedly supported with this approach: 1) many complex neural structures shared amongst arthropod groups have been inherited from ancient common ancestors, suggesting that the neural arrangements seen today have been carried over from antiquity; and 2) these same complex attributes are absent in numerous late-diverging lineages, supporting the hypothesis that secondary simplification of nervous systems is a common property of arthropods.
136

Relação entre densidade de larvas de Limnoperna fortunei na coluna d’ água e sua colonização em tanques-rede /

Melo, Taissa Juliana de January 2019 (has links)
Orientador: Maria Célia Portela / Resumo: Objetivou-se compreender a colonização do mexilhão-dourado, Limnoperna fortunei, por meio da relação entre densidade larval e incrustação das colônias. Também foram avaliadas as variáveis limnológicas e a densidade de Copepoda e Cladocera. A pesquisa foi realizada em piscicultura em tanques-rede no reservatório Chavantes, rio Paranapanema, município de Ipaussu, São Paulo. Entre janeiro e setembro de 2018 foi investigada a densidade de larvas de Limnoperna fortunei, Cladocera e Copepoda em três pontos e três profundidades (1,0; 2,5 e 5,0m) e o recrutamento do L. fortunei, mensal e acumulado, na superfície (15 x 15 cm) de tambores da piscicultura. Contagem e identificação das larvas de L. fortunei seguiram Cataldo et al. (2005) e de microcrustáceos o protocolo Zooplâncton de água doce: métodos qualitativo e quantitativo (CETESB, 2012). Os mexilhões aderidos aos substratos foram medidos com paquímetro digital e microscópio estereoscópico. O crescimento do molusco foi estimado utilizando a equação de Bertalanffy. Copepoda foram dominantes. Maior densidade de L. fortunei ocorreu de janeiro a março (máximo de 37.300 ind.m-3) com picos menores em maio e setembro e drástica redução de junho a agosto (menor que 5.000 ind.m-3). Maiores densidades de Copepoda e Cladocera também ocorreram de janeiro a março. No verão houve maior recrutamento do L. fortunei, com evidente redução no período mais frio. Portanto, o período reprodutivo influenciou diretamente na incrustação. Estimou-se que o ... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The objective was to understand the colonization of the golden mussel, Limnoperna fortunei, by means of the relation between larval density and incrustation of the colonies. The limnological variables and the density of Copepoda and Cladocera were also evaluated. The research was carried out in fish culture in fish cage in the Chavantes reservoir, Paranapanema River, municipality of Ipaussu, São Paulo. Between January and September 2018, the density of larvae of Limnoperna fortunei, Cladocera and Copepoda was investigated in three points and three depths (1,0, 2,5 and 5,0m) and the recruitment of L. fortunei, monthly and accumulated , on the surface (15 x 15cm) of fish farming drums. Count and identification of larvae of L. fortunei followed Cataldo et al. (2005) and microcrustaceans the Freshwater Zooplankton protocol: qualitative and quantitative methods (CETESB, 2012). The mussels adhered to the substrates were measured with digital caliper and stereoscopic microscope. Mollusk growth was estimated using the Bertalanffy equation. Copepoda were dominant. Higher density of L. fortunei occurred from January to March (maximum of 37,300 ind.m-3) with lower peaks in May and September and a drastic reduction from June to August (less than 5,000 ind.m-3). Higher densities of Copepoda and Cladocera also occurred from January to March. In the summer there was more recruitment of L. fortunei, with evident reduction in the colder period. Therefore, the reproductive period had a direct ... (Complete abstract click electronic access below) / Mestre
137

Taxonomia e novos registros de monogenea e copepoda parasitos de peixes actinopter?geos (Osteichthyes) no Brasil / Taxonomy and new records of monogenea and copepoda parasites of actinopterygian fishes (Osteichthyes) in Brazil

OLIVEIRA, Fabiano Paschoal de 06 April 2017 (has links)
Submitted by Jorge Silva (jorgelmsilva@ufrrj.br) on 2018-02-27T18:03:38Z No. of bitstreams: 1 2017 - Fabiano Paschoal de Oliveira.pdf: 3969824 bytes, checksum: 01879ccf451104bee02c819243b351cc (MD5) / Made available in DSpace on 2018-02-27T18:03:38Z (GMT). No. of bitstreams: 1 2017 - Fabiano Paschoal de Oliveira.pdf: 3969824 bytes, checksum: 01879ccf451104bee02c819243b351cc (MD5) Previous issue date: 2017-04-06 / CAPES / Between the period from march 2013 to november 2016 were collected and analyzed 195 specimens of hosts belonging to 25 species of actinopterygian fishes in Brazil, with the objective of perform a taxonomic study of your parasitic monogeneans and copepods. Two species of monogeneans, Sciadiclethrum araguariensis Paschoal, Scholz, Tavares-Dias & Luque, 2016 and S. edgari Paschoal, Scholz, Tavares-Dias & Luque, 2016 were described from two cichlids from the Araguar? River, State of Amap?, northern Brazil; in addition to the new species, new host and geographical records of six dactylogyrid monogeneans from cichlid fishes are presented from the Araguar? River and the Xing? River, State of Par?, Brazil. Two copepods of the family Philichthyidae Vogt, 1877, Colobomatus kimi Paschoal, Pereira & Luque 2016 and Leposphilus vogti Paschoal, Nagasawa & Luque 2016 parasites in the Upeneus parvus (Poey) and Micropogonias furnieri (Desmarest), respectively, in the litoral of the state of Rio de Janeiro, Brazil, are described and illustrated; In addition, an amendment diagnosis of the genus Leposphilus is provided based on the characters found in the present work. The copepod Hatschekia sp. n. is described based specimens collected on the haemulid fishes Anisotremus virginicus (Linnaeus) and A. surinamensis (Bloch) in the Bay of Angra dos Reis, State of Rio de Janeiro, Brazil, being this the first species of the family Hatschekiidae Kabata, 1979 described from the coast of Brazil. Beyond the descriptions s?o fornecidas novas informa??es sobre 15 esp?cies de cop?podes parasitas de 12 esp?cies de peixes marinhos de diferentes localidades litor?neas no Brasil; Are provided new information about 15 species of parasitic copepods found on 12 marine species of fishes in Brazil; these data including 12 new host records, eight new geographical records (locality) and first record of the genera Cresseyus and Pseudochondracanthus in the western South Atlantic. / Entre o per?odo de mar?o de 2013 a novembro de 2016 foram coletados e analisados 195 esp?cimes de hospedeiros pertencentes a 25 esp?cies de peixes actinopter?geos no Brasil, com objetivo de realizar um estudo taxonomico de seus monogen?ticos e cop?podes parasitas. Duas esp?cies de monogen?ticos, Sciadiclethrum araguariensis Paschoal, Scholz, Tavares-Dias & Luque, 2016 e S. edgari Paschoal, Scholz, Tavares-Dias & Luque, 2016 foram descritas a partir de dois ciclideos do rio Araguar?, Estado do Amap?, norte do Brasil; al?m das duas esp?cies, foram apresentados novos registros de hospedeiros e geogr?ficos de seis monogen?ticos dactilogir?deos a partir de peixes ciclideos do rio Araquari e do rio Xing?, Estado do Par?, Brasil. Dois cop?podes da fam?lia Philichthyidae Vogt, 1877, Colobomatus kimi Paschoal, Pereira & Luque 2016 e Leposphilus vogti Paschoal, Nagasawa & Luque 2016 parasitas de Upeneus parvus (Poey) e Micropogonias furnieri (Desmarest), respectivamente, do litoral do estado do Rio de Janeiro, Brasil, foram descritas e ilustradas; ademais uma altera??o do diagn?stico gen?rico de Leposphilus ? fornecido com base nos caracteres encontrados no presente trabalho. O cop?pode Hatschekia sp. n. ? descrita e ilustrada a partir de esp?cimes coletados dos peixes haemulideos Anisotremus virginicus (Linnaeus) e A. surinamensis (Bloch) provenientes da Ba?a de Angra dos Reis, Estado do Rio de Janeiro, Brasil, sendo esta a primeira esp?cie da fam?lia Hatschekiidae Kabata, 1979 descrita a partir do litoral do Brasil. Al?m das descri??es s?o fornecidas novas informa??es sobre 15 esp?cies de cop?podes parasitas de 12 esp?cies de peixes marinhos de diferentes localidades litor?neas no Brasil; estes dados incluem 12 novos registros de hospedeiros, 08 novos geogr?ficos (de localidade) e primeiros registros dos g?neros Cresseyus e Pseudochondracanthus no oeste do Atl?ntico Sul.
138

Food Quality Effects on Zooplankton Growth and Energy Transfer in Pelagic Freshwater Food Webs / Effekter av födokvalitet på djurplanktons tillväxt och på energiöverföringen i födovävar i sjöar

Persson, Jonas January 2007 (has links)
<p>Poor food quality can have large negative effects on zooplankton growth and this can also affect food web interactions. The main aims of this thesis were to study the importance of different food quality aspects in <i>Daphnia</i>, to identify potentially important differences among zooplankton taxa, and to put food quality research into a natural context by identifying the importance of food quality and quantity in lakes of different nutrient content.</p><p>In the first experiment, the RNA:DNA ratio was positively related to the somatic growth rate of <i>Daphnia</i>, supporting a connection between P content, RNA content, and growth rate. The second experiment showed that EPA was important for <i>Daphnia</i> somatic growth, and 0.9 µg EPA mg C<sup>-1</sup> was identified as the threshold below which negative effects on <i>Daphnia</i> growth occurred.</p><p>A field survey identified patterns in the PUFA content of zooplankton that could be explained by taxonomy and trophic position. <i>Cladocera</i> enriched EPA and ARA relative to seston, and <i>Copepoda</i> primarily enriched DHA. In a whole-lake experiment, gentle fertilization of an oligotrophicated reservoir increased the seston P content and the biomass of high quality phytoplankton (<i>Cryptophyceae</i>, high EPA content). This was followed by increases in zooplankton and fish biomasses.</p><p>An empirical model based on data from a literature survey predicted that food quantity is most important for zooplankton growth in oligotrophic lakes, and that food quality factors are more important in eutrophic lakes. Thus, zooplankton growth, and energy transfer efficiency in the food web, is predicted to be highest in mesotrophic lakes. The results predict that the strength and nature of food quantity and quality limitation of <i>Daphnia</i> growth varies with lake trophic state, and that some combination of food quantity and/or quality limitation should be expected in nearly all lakes.</p>
139

Chromosome number and phylogenetic relationships in selected species of North American diaptomus (Copepoda, Calanoida)

Kiley, Ann L. 03 June 2011 (has links)
The chromosome numbers of the eight following species of freshwater diaptomid copepods were examined to elucidate relationships between species: Aglaodiaptomus clavipes, A. leptoups, Leptodiaptomus ashlandi, A. minutus, A. sicilis, A. siciloides, Skistodiaptomus oregonensis, and S. pallidus. The specimens evaluates were collected from various lakes in Wisconsin including Lake Michigan. Squash mounts were prepared from female individuals for microscopic evaluation. Comparisons of chromosome numbers and chromosome morphology indicated that the species considered are not as closely related as might be suspected based on external morphological considerations. The chromosome numbers varied greatly between species and no consistant numbers within subgenera were observed, substantiating the idea that the species are clearly well separated phylogenetically. A technique for preparing chromosome squash mounts from formalin preserved specimens in presented.Ball State UniversityMuncie, IN 47306
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Risk and resources in the plankton: effects on copepod population growth and zooplankton community dynamics

Lasley, Rachel Skye 03 July 2012 (has links)
The focus of my thesis research is on the interplay between individual behavior, population dynamics and community-level processes within zooplankton communities in coastal Maine. The target organisms of my thesis work are marine copepods. Copepods are small (1-10 mm) crustaceans that perform the essential ecosystem function of consuming and assimilating primary production (phytoplankton) making it available to higher trophic levels such as commercially important fishes. Therefore, copepod population growth is of critical importance to marine food webs. Fertilization limitation has been suggested as a constraint on copepod population growth but field surveys describing the prevalence of fertilization limitation are lacking. During my doctoral research, I explored the in situ fertilization success of two marine copepod species, Temora longicornis and Eurytemora herdmani in coastal Maine. I collected monthly zooplankton samples and analyzed clutches from field-caught females using an egg-staining technique. My results indicate that both species exhibit fertilization limitation in nature and the factors correlated with their fertilization span population, community and ecosystem level factors. To determine a causal relationship between predator density and copepod mating success, I conducted laboratory experiments to assess the effects of a common mysid shrimp predator, Neomysis americana on Eurytemora herdmani mating success. I subjected males and females to predators or predator cues. I found that the presence of a mysid predator, or only a predator cue, reduced copulation frequency and spermatophore transfer leading to a 38-61% decrease in E. herdmani nauplii production. These results suggest that mysid predators can constrain copepod population growth through non-consumptive processes. To determine the effects that resources can impose on copepod behavior, I explored the behavioral and fitness consequences of Temora longicornis ingesting Alexandrium fundyense, a phytoplankton species that forms harmful algal blooms in coastal Maine. My results suggest that ingesting A. fundyense causes copepods to swim faster and with more directional persistence compared to control algae. Temora longicornis increased their average swimming velocity by 24%, which leads to a 24-54% increase in their theoretical encounter rate with predators. Therefore, these findings suggest behaviorally mediated copepod-algal interactions may have significant impacts on harmful algal bloom dynamics and the fate of toxins in marine food webs.

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