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Acesso aberto (Open Access)
Comunidades macrobentônicas da Reserva Biológica do Lago Piratuba (Amapá – Brasil)
(Universidade Federal do Pará, 2008) ALMEIDA, Mayk Ferreira de; ROSA FILHO, José Souto; http://lattes.cnpq.br/3223362071251898; ALBERNAZ, Ana Luisa Kerti Mangabeira; http://lattes.cnpq.br/1220240487835422
The structure of the macrobenthic communities was characterized in different climatic periods and areas of the Reserva Biológica do Lago Piratuba (Amapá-Brazil). The samplings occurred on June and November of 2005 (Meridional belt lake - lakes Comprido de cima, Bacia, Lodão, Grande, Comprido de Baixo, Canal Tobaco and estuary of the river Araguari) and of 2006 (eastern belt lake - lakes Piratuba, Jussara, Escara, Trindade, Maresia, Boiado and the Duarte stream and seven places in the coast (areas vegetated and not vegetated). At each site four samples had been collected, with a corer (0.0079 m2) buried 20 cm in the sediment. After collection samples were passed in a 0.3 mm mesh and the retained organisms were fixed in formalin 5%. The structure of the communities varied seasonally, with severe modifications in density, specific composition, richness, eveness and diversity among sampling occasions and environments (lakes/coast). A total of 54 taxa had been identified belonging to phyla: Annelida, Arthropoda, Mollusca and Nemertea. In the rainy seasonal it was recorded 36 taxa, and in the dry seasonal 42 taxa were recorded. Annelida was the most abundant taxon, representing always more than 48% of total organisms. In the lakes Insecta larvae, Mollusca and Oligochaeta were the dominant taxa. In the coast, Polychaeta and Crustacea were dominant. It was recorded 32 taxa in the lakes and mean density of 667 ind.m-2. In the coast 34 taxa were recorded and 1353 ind.m-2. The coastal non-vegetated area was richer and denser and showed the higher eveness. Benthic fauna from the Meridional belt lake and the Eastern belt lake behavioured distinctively among seasons. Three sub-environments had been identified based on the benthic fauna: freshwater environment - majority of the lakes of the Eastern belt, dominated by insects; transition environment (freshwater/coast) with mixed fauna (Polychaeta and Insecta); and coastal environment, with Polychaeta and Crustacea. The environmental characteristics best correlated with spatialtemporal changes in the benthic communities structure were water pH, electric conductivity and turbidity.
Acesso aberto (Open Access)
Dinâmica do carbono dissolvido no Rio Acre: variações espaciais e sazonais
(Universidade Federal do Pará, 2007) SOUSA, Eliete dos Santos; SALIMON, Cleber Ibraim; http://lattes.cnpq.br/4353834821288043; FIGUEIREDO, Ricardo de Oliveira; http://lattes.cnpq.br/2388049759708934
The main objective of this study was to study the dissolved carbon dynamics along a reach of the Acre River, evaluating the influence of Rio Branco city urban area and of the discharge from three of its tributaries (Riozinho do Rola, igarapé Judia and igarapé São Francisco), as well as the influence of hydrological seasonal changes. Samples were taken monthly, between December 2006 and September 2007, at five sites in Acre River and one site at the tributaries mouths. Each sample consisted of 1 liter of river/tributary water, which was submitted to filtering and aliquots withdrawn for dissolved organic carbon (DOC), dissolved inorganic carbon (DIC) and major ions (Ca2+, Mg2+, K+, Na+, NH4 +, HCO3 -, Cl-, SO4 2-, NO3 -, NO2 -, e PO4 3-) analysis. Electrical conductivity, pH, dissolved oxygen and water temperature measurements were also made. Mean annual pH in Acre River varied from 6.46 to 6.54 between sites and electrical conductivity presented mean values from 69.93 to 77.84 μS cm-1. In the tributaries, the mean annual pH ranged from 6.10 to 6.51 and electrical conductivity presented annual means from 54.08 and 153.03 μS cm-1. Na+ and Ca2+ were the dominant cations for both Acre River and its tributaries, while main anions were Cland SO4 2-. The mean annual DOC concentration in Acre River ranged from 4.62 to 5.17 mg l-1, with no significant difference among sampling sites. The tributaries’ mean annual DOC concentrations varied from 3.55 to 6.55 mg l-1. The concentrations were significantly higher in the high water period, with averages that ranged from 6.26 to 6.39 mg l-1 in Acre River sites. igarapé São Francisco was the only tributary that did not present differences between the seasons. Mean annual DIC concentration in Acre River ranged from 527.91 to 598.18 μM, with no significant difference among sampling sites. The higher concentrations were observed in the dry season, ranging from 816.31 to 998.52 μM. Mean annual DIC concentration in the tributaries ranged from 248.54 to 986.50 μM. Mean annual CO2 partial pressure (pCO2) in Acre River sites ranged from 3559 and 4059 ppm, with no significant differences among sites and with higher values in high waters. Based on these results, we conclude that the dissolved carbon dynamics in Acre River have not presented significant variations due to the tributaries discharge or due to the sewage discarded. On the other hand, hydrological seasonal changes are the most important drivers for changes in carbon dynamics.
Acesso aberto (Open Access)
Efeito de bacias e de variáveis ambientais na estrutura de comunidades de peixes de igarapés na região do interflúvio Madeira-Purus
(Universidade Federal do Pará, 2008) BARROS, Daniela de França; ZUANON, Jansen Alfredo Sampaio; http://lattes.cnpq.br/0161925591909696; ALBERNAZ, Ana Luisa Kerti Mangabeira; http://lattes.cnpq.br/1220240487835422
The main objective of this study was to investigate the richness and composition of the fish fauna in headwaters of streams in the Madeira-Purus interfluvial region, and if they are related to environmental variables and / or watersheds. Data was collected along two field campaigns, lasting approximately 20 days each, between the months of April and July 2007. A total of 22 streams were sampled, belonging to five different watersheds. Fish were captured with hand nets and small seine nets. Information on the structural characteristics of the streams and physical-chemical of water was also obtained. A total of 5509 fish were captured, belonging to 86 species, 22 families and six orders. Characiformes was the most diversified taxonomic group, followed by Gymnotiformes and Siluriformes. The species composition was influenced mostly by the width and depth of the channel, discharge and substrate. The presence of different environments around creeks has also contributed to the differences in fish species composition. The watersheds had strong effect on communities of fish. However, the results cannot allow to assert with certainty if differences in fish composition among watersheds are reflecting historical effects or environmental conditions.
Acesso aberto (Open Access)
A efetividade das unidades de conservação e das terras indígenas na contenção do desflorestamento na Amazônia Legal
(Universidade Federal do Pará, 2010) NUNES, Tássia do Socorro Serra; FERREIRA, Leandro Valle; http://lattes.cnpq.br/8103998556619871
Was investigated the effectiveness of the Conservation Units of Integral Protection, Conservation Units of Sustainable Use and Indigenous Lands in the inhibition of deforestation in the Amazon. Data analysis was processed in GIS (Geographic Information System) in ArcGIS 9.3. The statistical model developed to test the effectiveness of Protected Areas was based on the difference between the observed deforestation in Protected Areas and deforestation in Protected Areas estimated from the surrounding five kilometers and ten kilometers of Protected Areas. It was found that in forest area by the year 2007, the Protected Areas occupy approximately 40% of the Amazon. Conservation Units of Integral Protection occupied 7.5% of the Amazon, Conservation Units of Sustainable Use occupied 11.2% of the Amazon and Indigenous Lands occupied 21% of the Amazon. Was a significant difference in the proportion of area occupied by the types of Protected Areas among the Amazonian states. It was noted also that the internal rate of deforestation in the Conservation Units of Integral Protection and in the Indigenous Lands was lower than in the Conservation Units of Sustainable Use. The internal rate of deforestation in the Protected Areas was much lower than the rate of deforestation is external to these areas in the states of Mato Grosso, Para and Rondonia. According to the statistical model of effectiveness, 62.3% of the Protected Areas studied were effective in containing the deforestation. This model is an important instrument to direct public policy planning for the conservation of the Amazon, because it indicates the protected areas most threatened by deforestation. It is essential to establish urgently the creation of more Protected Areas in the Amazon and the consolidation of existing protected areas, since it is not known how long these areas will be able to maintain without the minimum necessary for their support.
Acesso aberto (Open Access)
Estudo dos potenciais impactos das mudanças climáticas e de alterações na cobertura vegetal nos recursos hídricos na Região Central da Amazônia
(Universidade Federal do Pará, 2008-01-31) SILVA, Flérida Seixas Moreno da; CÂNDIDO, Luiz Antonio; http://lattes.cnpq.br/7705103746743754; MOTA, Maria Aurora Santos da; http://lattes.cnpq.br/5817549281617240
This research focused on evaluating and quantifying the impacts in water availability in Amazônia Central Region, due to possible climatic change and land use changes, through a numerical modeling experiment using the Common Land Model (CLM) biosphere model, in off line mode. The results of 9 Ocean-Amosphere Copled Models and 3 climatic change scenarios from IPCC – AR4 was used, in order to establish the basin of climatic forcing of CLM model. It was also used the deforestation dynamic scenario in the case of business as usual, predicted for each year of 2001-2050 period. Thus, draining basin of Rio Cuieiras on Amazônia Central was considered. From the results of the models, the uncertainties of projections relative to precipitation and temperature, was analyzed for each simulations, considering the variability between the models and the CO2 emission scenario; as well as modifications in water and energy balance components associated to variations on forest cover and its substitution for pasture. The results indicate that, in the case of a scenario of climate change witch leads in a persistent decrease (increase) on annual mean rainfall, both runoff and water storage in soil will be directly affected. About modification in cover, the water and energy balance components was strongly affected by substitution of forest by pasture, showing decrease in evapotranspiration and increase on soil water storage and in total runoff.
Acesso aberto (Open Access)
O papel das trajetórias sociais na construção do território nas frentes pioneiras da Amazônia
(Universidade Federal do Pará, 2010-03-29) AMÉRICO, Maria do Carmo da Silva; COSTA, Francisco de Assis; http://lattes.cnpq.br/1820238947667908; VIEIRA, Ima Célia Guimarães; http://lattes.cnpq.br/3761418169454490
Distinct paths of beef production farmers in the municipality of São Felix do Xingu, southeastern Pará were studied. We linked concepts of geographic space and territory in this new pioneer region in the Amazon, with the highest annual deforestation rates, to the notions of paradigms and technological trajectories in a multidisciplinary approach. This work attempts to understand the Amazon reality using various scientific disciplines with emphasis on geography, economy and anthropology. As our core methodology for survey and data analysis we employed the Successive Coherence Analysis in order to carry out ethnographic studies of rural agents and employers to understand the relationship between the paths that develop those agents with the dynamics of the territory. It appears that the relationship between these two categories of agents is mutually dependent, not only related to the division of labor but also related to the geopolitics of land use of the territory.