Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1985. / Vita. Abstract. Includes bibliographical references (leaves 118-127). Also available via the Internet.

<p> I examined flow-ecology relationships among stream communities in the Ozark Highlands, USA. I sampled fish, crayfish, and benthic macroinvertebrates during two consecutive summers, including a drought year (2012) and a flood year (2013). Biological response variables related to community structure were assessed via two different statistical methods: an Information Theoretic approach relating response variables to <i>a priori</i> selected predictor variables incorporating hydrology, habitat, geomorphology, and water quality, and canonical ordination using forward selection to relate these same response variables to a large assortment of hydrologic metrics. In addition to assessing metrics related to predicted natural flow, flow alteration at gaged sites was also quantified and community metrics were assessed with respect to flow alteration. Additionally, I conducted a manipulative laboratory greenhouse experiment to examine the effects of stream drying, one of the major components of the natural hydrologic disturbance regime in the region, on stream fishes as well as benthic community structure. Hydrologic variation was often less important than other environmental variables and substantial temporal variation existed in flow-ecology relationships. Stream flow magnitude was the most important category of hydrologic metric overall, but there were key differences in which metrics were important for each assemblage and how those assemblages responded to those metrics. Flow alteration has a strong effect on Ozark riverine communities, and the most important categories of flow alteration affecting these communities are magnitude of average flows, and frequency, magnitude, and duration of high flows. The large number of important high flow metrics suggests that flood events may play a particularly crucial role in structuring aquatic assemblages in the region. I found that seasonal stream drying had strong species-specific effects on organisms in pool refuges, and that type of drying specifically affected periphyton growth. Overall, I found that the elucidation of flow-ecology relationships and management decisions that are based on those relationships face a variety of challenges: the complex interaction of hydrology with other kinds of environmental variables, temporal variation in the aquatic community, and the differential effects of flow metrics on different assemblages.</p>

Orientador: Raoul Henry / Banca: Alaíde Aparecida Gessner / Banca: Evanilde Benedito / Resumo: O objetivo deste estudo foi analisar a composição taxonômica e a densidade de macroinvertebrados associados à macrófita Eichhornia azurea (Swartz) Kunth em seis lagoas laterais ao Rio Paranapanema em sua zona de desembocadura na Represa de Jurumirim - SP. As amostragens foram realizadas em março e agosto de 2009, supostamente meses de estações chuvosa e seca, respectivamente. Em cada uma das seis lagoas, foram selecionados três bancos distintos de E. azurea para coleta do material biológico (macrófita e fauna associada) e medida das variáveis limnológicas: profundidade, transparência, temperatura, pH, condutividade elétrica e concentrações de oxigênio dissolvido e material em suspensão. A amostragem de E. azurea foi realizada com um retângulo de 0,1976 m2, utilizando-se uma tesoura de jardinagem para retirada do material vegetal, que foi lavado em solução de formol e água para remoção dos macroinvertebrados associados. Entre os períodos estudados diferenças significativas (p<0,05) foram encontradas tanto para as variáveis limnológicas, quanto para a densidade de alguns dos taxa de macroinvertebrados. Na comparação das lagoas entre si em março e agosto, com relação as variáveis limnológicas e densidade dos taxa de macroinvertebrados (em níveis de grandes grupos), o Teste Tukey apontou mais diferenças significativas (p<0,05) para março, embora alguns dos taxa de macroinvertebrados associados à E. azurea não tenha apresentado diferença significativa entre as lagoas em nenhum dos períodos amostrados. De acordo com a análise de componentes principais, o pH e oxigênio dissolvido são as variáveis que melhor explicam a ordenação das lagoas nos períodos de estudo. Com relação à fauna associada, em ambos os períodos a classe Insecta foi a mais abundante (com destaque a família Chironomidae), seguida pelo filo Crustacea e pela classe Clitellata... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The aim of this study was to analyze the taxonomic composition and density of macroinvertebrates associated with macrophyte Eichhornia azurea (Swartz) Kunth in six lagoons to the river side Paranapanema in its mouth zone into the Jurumirim Reservoir - SP. Samples were held in March and August 2009, supposedly months of rainy and dry seasons, respectively. In each of the six lagoons three different stands of E. azurea were selected for collecting biological material (macrophytes and associated fauna) and measurement of limnological variables: depth, transparency, temperature, pH, electric conductivity and concentrations of dissolved oxygen and suspended solids. The sampling of E. azurea was performed with a rectangle of 0,1976 m2, gardening shears was used to remove the plant material, which was washed in a solution of formaldehyde and water to remove associated macroinvertebrates. Between the two periods significant differences (p <0,05) were found for both limnological variables, and for the density of some of the taxa macroinvertebrates. In comparison with each other lagoons in March and August, related limnological variables and density of taxa of macroinvertebrates (levels in large groups), the Tukey test showed more significant differences (p <0,05) in March, although some of taxa of macroinvertebrates associated with E. azurea has not presented significant difference between the lagoons in any period sampled. According to principal components analysis, pH and dissolved oxygen are the variables that best explain the ordering of lagoons during the study periods. With respect to the associated fauna, in both periods the class Insecta was the most abundant (especially the family Chironomidae), followed by phylum Crustacea and the class Clitellata. However, comparing the richness of taxa in the months of sampling, it appears that higher values were recorded in August period... (Complete abstract click electronic access below) / Mestre

Made available in DSpace on 2014-06-11T19:35:05Z (GMT). No. of bitstreams: 0 Previous issue date: 1999-02Bitstream added on 2014-06-13T18:46:14Z : No. of bitstreams: 1 toscano_ias_dr_araiq.pdf: 387630 bytes, checksum: 64cc6245511279744bb2dd4a814e3afb (MD5) / Substâncias húmicas aquáticas (SHA) foram obtidas por processo de adsorção em resinas macroporosas não-iônicas, XAD 7 e XAD 2, dispostas em série. Após eluição com solução de NaOH, o extrato alcalino de SHA foi acidificado a pH 1,0 para separação em ácidos húmico (AH) que precipita, e ácido fúlvico (AF) o qual permanece em solução. Para caracterização físicoquímica do material húmico (AH e AF), foram feitas análise elementar, determinação do teor de substâncias húmicas e acidez total. Os resultados obtidos por UV-VIS e FTIR indicaram que AH apresenta maior número de grupos aromáticos em relação a AF, que em geral possui mais cadeias alifáticas. A aplicação da técnica imunoquímica, enzyme-linked immunosorbent assay (ELISA), para a determinação do herbicida atrazina em águas foi avaliada em amostra de água contendo alto teor de matéria orgânica (~35 mg L-1) e baixo valor de pH (3,8). O efeito matriz devido a presença de SHA pode ser notado pela perda de sensibilidade da técnica, ou seja, os valores de IC50 variaram de 60 ng L-1, na ausência de SHA, para 112 ng L-1 em concentrações acima de 10,0 mg L-1 de material húmico e para 137 ng L-1 em pH < 5,0. Além disto, pode-se inferir que a luz solar aumentou a velocidade de degradação da atrazina na presença de SHA formando produtos, com partes de suas estruturas, semelhantes ao produto original levando a resultados falso-positivos. A quantidade de material húmico presente na amostra de água foi a principal fonte de erro na análise de atrazina, levando à interações não-específicas entre as SHA e os reagentes enzimáticos. O procedimento ELISA, aplicado neste estudo, pode ser utilizado para determinação de atrazina desde que se faça diluição da amostra até cerca de 2,5 mg L-1 de húmicos e em pH alcalino (7,0 – 9,0). / Aquatic humic substances (AHS) were isolated from water samples using Amberlite XAD 7 and XAD 2. After elution with NaOH solution, the XAD concentrated AHS was fractioned at pH 1.0 resulting in fulvic acid (FA - supernatant) and humic acid (HA - slurry). All humic materials were characterized with respect to elemental analysis, amount of AHS and total acidity. UV and FTIR spectra showed HA aromatic character greater than FA. Enzyme-linked immunosorbent assay (ELISA) was evaluated by analyzing atrazine in rich-humic matter water sample (~35 mg L-1) and acid water (pH 3.8). From all the conditions studied the low pH (pH < 5.0) and high humic substances concentrations (>10 mg L-1) showed the greatest influence. The IC50 values to control sample (no humic) decreased from 60 ng L-1 to 112 ng L-1 to humic solution at >10 mg L-1 and to 137 ng L-1 at pH < 5.0. The presence of AHS alters the photochemical behaviour of atrazine by accelerating its degradation forming metabolites which can be recognized by the antibodies. The assay performance showed a strong dependence on the pH values and amount of humic matter. However, analysis could be carried out directly in samples containing HA or FA that had been adjusted the pH in the range between 7.0 and 9.0, and humic concentration at 2.5 mg L-1.

Made available in DSpace on 2014-10-09T12:33:07Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:06:17Z (GMT). No. of bitstreams: 0 / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Made available in DSpace on 2014-10-09T12:33:07Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:06:17Z (GMT). No. of bitstreams: 0 / Triclosan é um composto orgânico de baixa solubilidade que vem sendo utilizado em formulações de cremes dentais e faciais, xampu, sabonetes, embalagens de gêneros alimentícios e diversos tipos de materiais, tais como, adesivos, brinquedos, sapatos, selantes, tintas, colchão, roupas, pisos, toldos e rejuntes. O amplo uso deste composto deve-se à grande eficácia contra bactérias Gram negativas e Gram positivas. Por seu extenso uso, evidências da presença de Triclosan têm sido frequentemente relatadas em efluentes urbanos e industriais, águas superficiais e sedimentos de ambientes dulcícolas, estuarinos e marinhos, como também em organismos aquáticos como algas, peixes e mamíferos. Neste contexto, o presente estudo avaliou a toxicidade aguda e crônica de Triclosan para diferentes invertebrados marinhos de águas tropicais. Para tanto, ensaios de toxicidade aguda foram realizados com o copépodo Nitokra sp (mortalidade) e com o ouriço-do-mar Lytechinus variegatus (taxa de fertilização). Para a avaliação do efeito crônico, ensaios de toxicidade de curta duração (desenvolvimento embriolarval) foram realizados com o ouriço-do-mar L. variegatus e Perna perna. Além desses métodos, o ensaio do Tempo de Retenção do Corante Vermelho Neutro foi empregado com a finalidade de se avaliar os efeitos do Triclosan sobre a estabilidade da membrana lisossômica de hemócitos de P. perna. Na avaliação do efeito agudo, o valor médio da CL(I)50;96h encontrada para o copépodo foi de 0,20 mg.L-1 enquanto que o valor médio da CI(I)50;1h para ouriço-do-mar foi de 0,28 mg.L-1. Já na avaliação do efeito crônico, o valor médio da CI(I)50;24h para ouriço-do-mar foi de 0,14 mg.L-1 e para o molusco bivalve a média da CI(I)50;48h, foi de 0,13 mg.L-1. O efeito na estabilidade da membrana lisossômica de hemócitos de P. perna ocorreu em concentrações a partir de 12 ng.L-1. Estes resultados evidenciam o risco ecológico da introdução contínua desse composto em ambientes marinhos, e devem ser considerados para identificação de concentrações seguras e futura regulação do bactericida Triclosan na legislação ambiental nacional e internacional. / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

<p> As growing human populations put an increasing demand on finite ocean resources, fisheries management tools rely ever more on high quality inputs and a comprehensive understanding of model factors. Stock assessment modeling for South Atlantic (SA) King Mackerel, <i>Scomberomorus cavalla </i>, uses inputs such as abundance indices, growth parameters, and fisheries landings. However, one underlying assumption in this modeling system is there are measurable connections among life stages. A juvenile abundance index developed from the SEAMAP-SA Coastal Trawl Survey (CTS) is presumed to represent ecological recruitment. Very weak correlations to other life stage proxies suggested a deficiency with the juvenile abundance index accuracy and indicated data exploration into the index formulation was needed. Examination of CTS juvenile length frequencies support that the smallest juveniles appear in the summer and spring juveniles are from overwintering of the previous year class. Juvenile abundance indices developed using year class (year in which a fish is spawned) rather than year of sampling (as done for previous assessments) showed substantial differences, in particular lowering AIC values indicating an improvement in model accuracy. Evidence of seasonal and regional variation with CTS juveniles prompted the development of separate age 0 and age 1 indices. Correlations of these indices to fisheries-derived year class strength suggested the age 0 index to be the best indicator of initial juvenile king mackerel abundance while the age 1 index reflects abundance after high early life stage mortality. Data exploration also was conducted for potential environmental variables impacting age 0 and age 1 abundance. Relationships were found between age 0 abundance and freshwater input, the Gulf Stream, hurricane activity, and predator abundance and between age 1 abundance and freshwater input and hurricane activity. This research provides not only valuable baseline knowledge for SA king mackerel juveniles, but also findings pertinent for their management. </p><p>

M.Sc. (Botany) / Please refer to full text to view abstract

M.Sc. / The main objective of this study was to perform active biomonitoring in the Rietlvlei Wetland System. Active biomonitoring, which can be defined as “the translocation of organisms from one place to another and quantifying their biochemical, physiological and/or organismal responses for the purpose of water quality monitoring” (De Kock and Kramer, 1994), has several advantages over the chemical monitoring system. Effluents often are complex and poorly characterized mixtures of a large number of chemicals. A combination of many chemicals being present in very small amounts (even below detection limits) can have a substantial impact on organisms, and a chemical-based approach may not identify the source of pollution nor will effect of synergism or antagonism be taken into account (Smolders et al., 2003). A suite of biomarkers of oxidative stress and histopathology were investigated in the fish Oreochromis mossambicus and the mollusk Melanoides tuberculata. The organisms were bred under laboratory conditions. They were deployed during the high-flow and low-flow periods, in cages at three sites down the flow gradient of the Rietvlei wetland system, to determine spatial and temporal variations in biomarker responses and general water chemistry in the system. The oxidative stress biomarkers analyzed were catalase (CAT), superoxide dismutase (SOD), peroxidase (GPx), as well as levels of reduced glutathione (GSH) and lipid peroxidation as malondialdehyde (MDA). There was evidence of presence of chemicals inducing oxidative stress in the organisms as indicated by the high levels of MDA, GSH and GPx. Induction of CAT and SOD was not substantial due to possible inhibitory factors. This study established that organism transplantation is a feasible strategy for biomonitoring. Overall, no distinct variations were observed in the spatial and temporal comparisons in all the biomarker responses. The findings of this investigation also provide a basis for further investigation into the application of these biomarkers in ecological risk assessment. / Dr. V. Wepener

The effects of the application of increasing concentrations of the growth retardant paclobutrazol (PBZ) to in vitro cultures of Populus and Betula species was studied, with a view to translating the effect into the field, and ultimately to control undesired tree growth commercially. Plant growth and associated regulatory effects were studied under controlled conditions over an eight to twelve week culture period, after which explants were harvested. At harvest, explants of both species were removed from their culture universals after growing on hard agarose gel media containing a range of PBZ concentrations. Explant fresh weight, height and dry weight was recorded. Spent culture medium was frozen, thawed and centrifuged for analysis, by High Performance Liquid Chromatography (HPLC), of PBZ uptake. Other investigation carried out included the influence of PBZ on explants' response to directional light, and the phytosterol content of explant leaves. It was shown that treatments of PBZ, irrespective of concentration, had a regulatory effect on the growth of explants of both species. Recorded height, fresh weight and dry weight of explants showed a reduced growth proportional with increased PBZ concentration. Explant response to the higher concentrations was different for each species, with Betula showing a higher degree of retardation at lower concentration than Populus. Uptake of PBZ also appeared to be species dependent, the average uptake of the available PBZ being 70% and 51% for Populus and Betula, respectively. Even though there was very little growth at high concentration, explants appeared reasonably healthy; no symptoms associated with tree decline, chlorosis, die back and or death, were observed on explants treated with PBZ, however a failure to leaf and severe stunting indicated potential over regulation at 5 pM in Betula explants. This investigation has shown that a dose-dependant response can be obtained from tissuecultured tree species and that the response appears to be species specific.