IO - Artigos publicados em periódicos
URI permanente para esta coleçãohttps://rihomolog.furg.br/handle/1/362
Navegar
500 resultados
Resultados da Pesquisa
- ItemThe small-scale urban reservoir fisheries of Lago Paranoá, Brasília, DF, Brazil(2007) Walter, Tatiana; Petrere Junior, MiguelIn many cases in large urban centers, which have appropriate waterbodies, small-scale fisheries are the only source of cheap protein for the poor. In Lago Paranoá, located in Brasília, the capital city of Brazil, fishing was studied by conducting interviews with 53 fishers filling in logbooks from March, 1999 to March, 2000 in three fishing communities. The fishers come from the poorest towns around Brasília, known as satellite-towns. They have been living there on average for 21.7 years (s = 9.6 years), their families have 4.9 members (s = 3.6) on average and 44.2% do not have a basic education. However, such characteristics are similar to the socioeconomic indices of the metropolis where they live. In spite of being illegal between 1966 and 2000, fishing generated an average monthly income of U$ 239.00 (s = U$ 171.77). The Nile Tilapia Oreocrhromis niloticus is the main captured species (85% of a total number of landings in weight of 62.5 t.). Fishing is carried out in rowing boats, individually or in pairs. The fishing equipment used are gillnets and castnets. Gillnets were used actively, whereby the surface of the water is beaten with a stick to drive Tilapias towards nets as they have the ability to swim backwards. This fishing strategy was used in 64.7% of the fisheries, followed by castnets (31.1%) and by gillnets which were used less (4.2%). The fish is sold directly in the streets and fairs of the satellite-towns to middlemen or to bar owners. Three communities have different strategies in terms of fishing equipments, fishing spots and commercialization. Consequently, there are statistically significant differences in relation to the monthly income for each one of these communities.
- ItemLoricate Choanoflagellates from the South Atlantic coastal zone (~32 °S) including the description of Diplotheca tricyclica sp. nov.(2008) Bergesch, Marli; Odebrecht, Clarisse; Moestrup, ØjvindThe biodiversity of marine heterotrophic protists is poorly known in the South Atlantic coastal zone (~32 °S) especially regarding the nanoflagellates. The presence of loricate choanoflagellates was reported for the first time in the Patos Lagoon estuary and the adjacent coastal zone. Seventeen species of eleven genera of loricate choanoflagellates were observed between October 1998 and May 2000 in fixed water samples (lugol’s solution + glutaraldehyde) in a JEM 100-SX transmission electron microscope. Most species were recorded in euhaline and mixopolyhaline waters during the spring and summer, none in autumn and a few (four) in winter. The absence of choanoflagellates at the more sheltered inshore stations is due freshwater influence, and at the beach station, probably due the strong wave action. The probably cosmopolitan species Pleurasiga minima , Cosmoeca norvegica , C. ventricosa and Parvicorbicula circularis were present in spring or summer in the estuary channel and coastal area while Stephanoeca diplocostata which apparently prefers lower temperature, was recorded in winter. Calotheca alata and Campyloacantha spinifera are mainly temperate species and were present in spring. The new species Diplotheca tricyclica was recorded at the estuary channel in the summer 1999, in high salinity water.
- ItemPalinomorfos do perfil sedimentar de uma turfeira em São Francisco de Paula, Planalto Leste do Rio Grande do Sul, Sul do Brasil(2007) Leonhardt, Adriana; Lorscheitter, Maria Luisa(Palynomorphs of the sedimentary profile of a bog, São Francisco de Paula, Eastern Plateau of Rio Grande do Sul, southern Brazil). This paper aims at giving basic reference material to the study of plant succession in the Quaternary Brazilian southern plateau. Therefore, it presents the palynological analysis of 22 samples, taken along one sedimentary profile of 286 cm, in a bog of Rio Grande do Sul Eastern Plateau, corresponding approximately to the last 25000 years. The chemical processing of the samples followed the conventional method and the analysis was made by light microscopy. Palynomorphs corresponding to 10 fungi, 6 algae, 3 bryophytes and 16 pteridophytes were examined. The material, especially spores, is described and illustrated. The descriptions are accompanied, whenever possible, by ecological data of the original organism.
- ItemPólen de gimnospermas e angiospermas do perfil sedimentar de uma turfeira em São Francisco de Paula, Planalto Leste do Rio Grande do Sul, Sul do Brasil(2008) Leonhardt, Adriana; Lorscheitter, Maria Luisa(Pollen of gymnosperms and angiosperms of the sedimentary profile of a bog, São Francisco de Paula, Eastern Plateau of Rio Grande do Sul, southern Brazil). This pollen catalogue aims at helping the study of paleoenvironmental reconstructions by palynology of sediments in southern Brazil Plateau. It presents gymnosperms and angiosperms pollen found in a sedimentary profile from a bog of Rio Grande do Sul Eastern Plateau. The profile has 286 cm long, corresponding approximately to the last 25,000 years. The 22 samples were collected in regular intervals in the profile, chemically treated following the standard method and analyzed by light microscopy. Pollen grains from two gymnosperms and 43 angiosperms (one Magnoliidae, five Hamamelidae, six Caryophyllidae, six Dillenidae and 25 Rosidae) are presented. The pollen material is described and illustrated. The descriptions are accompanied, whenever possible, by ecological data of the original sporophyte.
- ItemDetermination of extractable fluoride in contaminated soils with ion-selective electrode(2003) Mirlean, Nicolai; Baraj, Besnik; Garcia, Marina Reback Domingues; Niencheski, Luis Felipe Hax; Baisch, Paulo Roberto Martins; Casartelli, Maria Regina de Oliveira; Robinson, DanielIn a factorial design study involving the determination of F- by ion-selective electrodes, a significant interference was demonstrated for Fe, with an even more pronounced interference for Al. The fluoride leaching procedure from polluted soil showed more reliable results using 0.5 M citric acid
- ItemShort term variability of chlorophyll a and phytoplankton composition in a shallow area of the Patos Lagoon estuary (Southern Brazil)(2007) Yoshihiro, Carlos Cesar Otuka Fujita; Odebrecht, ClarisseA variabilidade temporal em curta escala de clorofila a, abundância e composição de ftoplâncton e ciliados e de fatores abióticos foram analisados no estuário da Lagoa dos Patos durante dois períodos, o primeiro na primavera (Outubro/Novembro 2004) e o segundo no verão (Janeiro/Fevereiro 2005). As amostragens foram realizadas em uma estação fixa, a cada 2h30min para as análises de clorofila a, salinidade, temperatura, transparência da água, velocidade e direção da corrente e, uma vez ao dia, para as de fitoplâncton e ciliados, seston e nutrientes inorgânicos dissolvidos. Na primavera, a direção do vento variou em intervalos de aproximadamente dois dias, e a precipitação pluviométrica foi elevada (212.9 mm), enquanto que no período de verão a direção do vento variou menos, aproximadamente a cada cinco dias, e a precipitação pluviométrica foi menor (32.5 mm). A ação da precipitação pluviométrica e direção do vento controlaram a temperatura, salinidade, transparência da água e clorofila a na área rasa do estuário, associados com ciclos mais curtos na primavera do que no verão. O teor dos nutrientes inorgânicos dissolvidos foi diferente nos dois períodos, com o silicato mais alto na primavera (média 108 µM) do que no verão (média 69 µM), e nitrato e amônia, como os principais elementos nitrogenados na primavera e no verão, respectivamente. A presença de espécies lacustres e marinhas na área de estudo esteve associada à relação entre o vento e salinidade, com ventos de Sul favorecendo a entrada de diatomáceas e de dinoflagelados marinhos e, de Nordeste, associados com a descarga de água doce, contendo cianobactérias e clorófitas. A resposta da salinidade e da assembléia planctônica à ação do vento foi mais rápida (escala de horas) na primavera do que no verão (3-4 dias). Foi evidenciado que, processos de alta freqüência mediados pelo vento, gerando flutuações na descarga de água doce, em período similar ao da taxa de divisão celular, 1-2 dias, são de grande importância na ecologia da laguna. As variações no fluxo de água doce, associadas com a direção do vento, controlam a acumulação da clorofila a na área de estudo, podendo impedir, atrasar ou favorecer o início da floração de diatomáceas na primavera. No verão, processos herbívoros pelágicos e bentônicos aparentemente têm um importante papel no controle da biomassa do fitoplâncton.
- ItemSalinity effects on osmoregulation and growth of the euryhaline flounder paralichthys orbignyanus(2002) Sampaio, Luís André Nassr de; Bianchini, AdaltoThe flounder, Paralichthys orbignyanus, is found in coastal and estuarine waters of the Western South Atlantic Ocean. It is being considered for aquaculture due to its high market price and wide tolerance to environmental factors such as salinity, pH, and nitrogenous compounds. The objective of this study was to characterize the ionic and osmotic regulation of P. orbignyanus over the range of its tolerated ambient salinities (0 – 40x) and to evaluate the survival and growth in freshwater (0x) and seawater (30x) over 90 days. After 15 days of exposure to different salinities (0x, 10x, 20x, 30xand 40x), plasma osmolality and ionic (Na + , Cl , K + and Ca2 + ) concentrations slightly increased with salinity. The isosmotic point was estimated as 328.6 mOsm kg 1 H2O and corresponded to 10.9xsalinity. After 90 days, survival was similar in freshwater and seawater, but osmo- and ionoregulation was significantly affected in freshwater and flounders reared in this medium showed a lower growth rate than those reared in seawater. Based on the results from this study, P. orbignyanus can be characterized as a marine/estuarine euryhaline teleost capable of hyper/ hypo iono- and osmoregulation over the fluctuating salinity regime faced by this species in the environment. Furthermore, results suggest that the lower growth rate exhibited by P. orbignyanus in freshwater could be due, at least partially, to a higher energy expenditure associated to a higher branchial Na + , K + -ATPase activity in this environment. D 2002 Elsevier Science B.V. All rights reserved.
- ItemMultiyear measurements of the oceanic and atmospheric boundary layers at the Brazil-Malvinas confluence region(2009) Pezzi, Luciano Ponzi; Souza, Ronald Buss de; Acevedo, Otávio Costa; Wainer, Ilana Elazari Klein Coaracy; Mata, Mauricio Magalhães; Garcia, Carlos Alberto Eiras; Camargo, Ricardo deThis study analyzes and discusses data taken from oceanic and atmospheric measurements performed simultaneously at the Brazil-Malvinas Confluence (BMC) region in the southwestern Atlantic Ocean. This area is one of the most dynamical frontal regions of the world ocean. Data were collected during four research cruises in the region once a year in consecutive years between 2004 and 2007. Very few studies have addressed the importance of studying the air-sea coupling at the BMC region. Lateral temperature gradients at the study region were as high as 0.3C km1 at the surface and subsurface. In the oceanic boundary layer, the vertical temperature gradient reached 0.08C m1 at 500 m depth. Our results show that the marine atmospheric boundary layer (MABL) at the BMC region is modulated by the strong sea surface temperature (SST) gradients present at the sea surface. The mean MABL structure is thicker over the warmside of the BMC where Brazil Current (BC) waters predominate. The opposite occurs over the coldside of the confluence where waters from the Malvinas (Falkland) Current (MC) are found. The warmside of the confluence presented systematically higher MABL top height compared to the coldside. This type of modulation at the synoptic scale is consistent to what happens in other frontal regions of the world ocean, where the MABL adjusts itself to modifications along the SST gradients. Over warm waters at the BMC region, the MABL static instability and turbulence were increased while winds at the lower portion of the MABL were strong. Over the coldside of the BC/MC front an opposite behavior is found: the MABL is thinner and more stable. Our results suggest that the sea-level pressure (SLP) was also modulated locally, together with static stability vertical mixing mechanism, by the surface condition during all cruises. SST gradients at the BMC region modulate the synoptic atmospheric pressure gradient. Postfrontal and prefrontal conditions produce opposite thermal advections in the MABL that lead to different pressure intensification patterns across the confluence. Ci
- ItemOptimum multiparamenter analysis of the weddell sea water mass structure(2005) Pereira, Rodrigo Kerr Duarte; Mata, Mauricio Magalhães; Garcia, Carlos Alberto Eiras
- ItemDescrição estatística da variabilidade de baixa frequência da Corrente da Austrália Oriental do Experimento de Circulação Oceânica Mundial PCM3 Current Meter Array(2006) Mata, Mauricio Magalhães; Wijffels, Susan; Church, John Alexander; Tomczak, MatthiasO conjunto de dados usado no estudo atual consiste na matriz Pacific Current Meter 3 (PCM3), que foi uma parte significativa da contribuição australiana para o World Ocean Circulation Experiment para estudar a variabilidade da Corrente Leste Australiana (EAC), e estava operacional entre Setembro de 1991 e março de 1994. A análise espectral de preservação de área foi usada para investigar as escalas de tempo típicas observadas pelos medidores de corrente. Como regra geral, os espectros das camadas superiores das amarras rasas (1, 2 e 3) e profundas (4, 5 e 6) têm um pico distinto na faixa de meso escala temporal (períodos entre 70 e 170 dias), com uma redistribuição geral de energia para as frequências mais altas perto do fundo do oceano. Este pico foi relacionado com a variabilidade de redemoinhos do sistema EAC, que influencia as flutuações do jato principal atual. Os modos verticais do perfil de velocidade mostram que o forte sinal baroclínico intensificado na superfície do EAC dominou a variabilidade no local do ancoradouro 4. Mais longe da costa, a configuração predominante se assemelha mais ao modo barotrópico. Em última análise, a análise de funções ortogonais empíricas espaciais (EOF) aponta o impacto da presença/ausência do jato EAC na matriz.