Navegando por Assunto "Densidade"

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Acesso aberto (Open Access)
Distribuição espacial e temporal da comunidade de rotifera na usina hidrelétrica de Tucuruí-PA, Brasil
(Universidade Federal do Pará, 2015) BEZERRA, Márcia Francineli da Cunha; NAKAYAMA, Luiza; http://lattes.cnpq.br/3771896759209007; OHASHI, Otávio Mitio; http://lattes.cnpq.br/5547874183666459
Acesso aberto (Open Access)
Espécies arbóreas presentes na zona urbana de Altamira - Pará: índices espaciais e diversidade florística
(Universidade Federal do Pará, 2023-04-28) FEIO, Elnatan Ferreira; VELOSO, Gabriel Alves; http://lattes.cnpq.br/9757471213923099; HTTPS://ORCID.ORG/0000-0002-3655-4166; HERRERA, Raírys Cravo; http://lattes.cnpq.br/2153779197306503; https://orcid.org/0000-0002-9699-8359
In recent decades, the interest in studying the urbanization process in cities has become an extremely important subject, since this phenomenon is not planned. Disregarding regional differences, it becomes very distant to design more sustainable cities. One of the ways to achieve this sustainability is by promoting actions that encourage the insertion of afforestation achieving positive effects, such as the alleviation of the heat resulting from asphalting and the implementation of urban spaces. Thus, the promotion of afforestation in cities is one of the ways to minimize the adverse effects of climate in cities and improve the quality of life of the inhabitants. This work was carried out at the headquarters of the municipality of Altamira, located in the southwest region of Pará state. It was performed in three stages: (i) mapping of tree planting from manual vectorization to generate a cloud of points that enabled the analysis through the application of Kernel Density Statistics of the spatial distribution of tree species using calculation of environmental parameters for estimative, such as Vegetation Coverage Index (CVI) and Percentage of Vegetation Coverage (PCV); (ii) acquisition of remote sensing images with low cloudiness during the dry season, referring to the years 2011 and 2021 from the Satellites Landsat 5 Sensor TM and Landsat 8 Sensor Tirs, respectively, with images acquired on National Institute for Space Research (INPE) website; and (iii) survey of tree census in three neighborhoods of the city based on the largest coverage indices calculated in the first stage of the research to determine the Shannon-Weaver, Simpson, and Pielou Equability Indices. It was observed that the distribution of afforestation in Altamira is very variable and deficient, where most of the city's neighborhoods have a tree density deficit. The central neighborhoods are the most consolidated and have the highest densities of individuals. The PCV was 0.49% and the ICVH was 1.72 m² of canopy/inhabitant. Values under recommended by the United Nations Organization - UN and the Brazilian Society of Urban Arborization - SBAU. For the year 2011, the terrestrial thermal conditions in the city of Altamira varied between a minimum of 23.97°C and a maximum of 34.80°C, maintaining a constant around 32°C in the urbanized area, out of line with the maximum temperature 34°C was registered in a few points of the city, with an average temperature of 32.09°C at Centro neighborhood. In 2021, the temperature in Altamira reached a minimum of 23.35°C and a maximum of 33.89°C. The result of calculating the indices for the Premem, Jardim Uirapuru and Esplanada do Xingu neighborhoods showed the following values, respectively: a) Shannon-Weaver diversity (H'): 1.73, 1.81, 2.28; b) Pielou equability (J'): 0.65, 0.57, 0.72, and c) Simpson (C): 0.69, 0.71, 0.85, respectively. Qualitative analysis indicated that the higher the value of C, the lower the diversity of species, therefore, the highest distributed diversity is found in the Premem neighborhood. For the quantitative analysis, 793 tree individuals were cataloged, divided into 61 species, belonging to 40 botanical families which was found that 68% are exotic species and 32% are native. It is observed that the arrangement of the spatial distribution of urban trees did not follow the growth of the urban fabric, allowing the emergence of areas with low tree density which ended up in the urgency of a policy elaboration that contemplates green areas in our city, in order to humanizing roads and public areas and contributing to the regulation of the microclimate in Altamira, with positive effects on the well-being of the population and those who transit through here. Thus, this study has the necessary attributes to support urban planning in actions aimed at promoting comfort and the future attenuation of thermal sensation events, valuing the planting of native species to the detriment of exotic ones.
Acesso aberto (Open Access)
Identificação e caracterização das massas d´água da Plataforma Continental do Maranhão, durante os períodos seco (Novembro, 1997) e chuvoso (Junho 1999)
(Universidade Federal do Pará, 2007-10-26) PONTES, Paulo Henrique Parente; KAMPEL, Milton; http://lattes.cnpq.br/0063119667740811; EL-ROBRINI, Maâmar; http://lattes.cnpq.br/5707365981163429; https://orcid.org/0000-0001-7850-1217
The Maranhão Continental Shelf (MCS) between the mouths of Gurupi and Parnaíba rivers is 203 km wide on the occidental coast and 72 km from Tubarão Bay toward southeast. The Maranhão coast is distinct: there are Maranhenses Reentrances in the Northwest; the dunes coast in the eastern side, being separated by the Golfão Maranhense, where the Mearim river, whose discharge is about 770 m3/s, discharges its fresh water. Other small rivers like Gurupi, Maracaçumé, Turiaçu, Itapecuru and Parnaíba discharge fresh water on the shore. The parameters of temperature, salinity and density were used to identify and characterize the water masses during dry season (november, 1997) and rainy season (june, 1999) in order to study seasonal variability of the local water masses. Images of Sea SurfaceTemperature (SST) obtained from Advanced Very High Resolution Radiometer (AVHRR) from NOAA satellites were used to observe its variation and verify some oceanographic features. The time series of monthly averages of images from AVHRR Pathfinder of SST with 4 km resolution (from 1985 to 2001), obtained from Instituto Nacional de Pesquisas Espaciais (INPE), was used to study the temporal and spatial SST variability through the calculation of climatological mean and its monthly SST changes in three points of the MCS to see if there are substantial changes in the features of the MCS waters during El-Niño/La-Niña seasons, since those phenomena can provoke (or not) great changes in the superficial water masses and in the local circulation. During the dry season (1997), it was observed that only Tropical Water, which is a water mass occurred, proving that at this season the continental water does not act on the MCS. However, during rainy season (1999) there were Coastal Water, Mixture Water, Tropical Water and South Atlantic Central Water. The Coastal Water is a water mass that comes from the rivers that discharge in the MCS. Mixture Water is a mixture of oceanic and continental water. So the presence of these two masses in the MCS proves that continental water occurred in the field of study during that period. The MCS water masses have the following physical characteristics: (i) Tropical Water: salinity over 36, temperature between 26,6° and 28,7°C and density between 23 kg/m³ and 23,8 kg/m³, which during the dry season occurs since the surface until more than 60 m of depth, while during rainy season it only occurs 40 km from the coast, from the surface until deeper 60 m; (ii) Coastal Water: salinity under 33, temperature between 28° and 29,4°C and density between 19 kg/m³ and 21,4 kg/m³, it occurs along 10km from the coast being also found from the surface until 28 m; (iii) Mixture Water: has salinity values between 33 and 36, temperature between 25,8º and 28,75ºC and density between 21,8 kg/m3 and 23,8 kg/m3 , and can be observed until 60 km from the coast along surface until 60 m; (iv) South Atlantic Central Water has salinity between 35,6 and 36, temperature under 18ºC and density between 23,9 kg/m3 and 25,8 kg/m3 that can be found 31 km from the coast and over 50 m depth. In the MCS, the AVHRR/NOAA images has shown low variation the SST field over the MCS. In November, 1997 maximum SST variation was 2,5ºC (minimum of 27°C and maximum of 29,5ºC) almost the same data obtained in situ where the maximum of SST was 28,6°C and minimum of 27,1°C. In the images of june, 1999, the oscillation of this parameter was between 27° and 29°C, similar to the data obtained during the ocean cruse of the same year that were of 27,4°C (minimum) and 29,2ºC (maximum). The graphics of SST anomaly in three different geographical sites of the MCS show a slight SST anomaly oscillation during the 1997/98 El-Niño event. The SST anomaly is higher in the MCS during 1998, which is between this work’s oceanographic expeditions. Therefore there was no significant influence of this phenomenon on the water masses of the MCS temperature characteristics during the data acquisition period. The occurrence of different water masses in the MCS region is related mainly to the seasonality on the area of study, which presents larger estuarine influence during the rainy season and little or no influence during the dry period, as can be confirmed through the predominance of oceanic waters (Tropical Waters) during the dry period and the presence of coastal waters and mixture water in the rainy season, determining clearer water stratification.
Acesso aberto (Open Access)
Microfitoplâncton de águas costeiras amazônicas: Ilha Canela (Bragança, PA, Brasil)
(Sociedade Botânica do Brasil, 2008-09) SOUSA, Eliane Brabo de; COSTA, Vanessa Bandeira da; PEREIRA, Luci Cajueiro Carneiro; COSTA, Rauquírio André Albuquerque Marinho da
Seasonal and nyctemeral variations of the microphytoplankton were studied at a fixed station (00º46'37.2''S-046º43'24.5''W) on Canela Island (North Brazil) in September and December/2004 (dry season) and in March and June/2005 (rainy season). Samples for qualitative phytoplankton studies were obtained by filtering 400 L of surface water in the surf zone of the island through plankton nets (65 μm mesh size). Field work was carried out during spring tides and samples were collected every 3 hours during a 24-hour period. The collected material was fixed in neutral formaldehyde at 4%. Simultaneously, salinity of the water surface was also measured. Salinity showed significant variation throughout the study period, ranging from 26.1 (June/2005) to 39.0 (December/2004), characterizing the environment as euhaline-polyhaline. A total of 130 taxa were identified, belonging to Cyanophyta (two taxa), Bacillariophyta (115 taxa) and Dinophyta (13 taxa). Diatoms were the dominant group of microphytoplankton at Canela Islan
Acesso aberto (Open Access)
Use of intertidal areas by shrimps (Decapoda) in a brazilian Amazon estuary
(2014-03) SAMPAIO, Herbet Aranha; MARTINELLI-LEMOS, Jussara Moretto
The present work investigated the occupation and the correlation of the shrimp abundance in relation to environmental variables in different habitats (mangroves, salt marshes and rocky outcrops) in an Amazon estuary. The collections were made in August and November 2009, at low syzygy tide on Areuá Beach, situated in the Extractive Reserve of Mãe Grande de Curuçá, Pará, Brazil totaling 20 pools. In each environment, we recorded the physical-chemical factors (pH, salinity, and temperature) and measured the area (m²) and volume (m³) of every pool through bathymetry. The average pH, salinity, temperature, area and volume of tide pools were 8.75 (± 0.8 standard deviation), 35.45 (± 3), 29.49 °C (± 2.32), 27.41 m² (± 41.18), and 5.19 m³ (± 8.01), respectively. We caught a total of 4,871 shrimps, distributed in three families and four species: Farfantepenaeus subtilis (98.36%) (marine) followed by Alpheus pontederiae (0.76%) (estuarine), Macrobrachium surinamicum (0.45%) and Macrobrachium amazonicum (0.43%) predominantly freshwater. The species F. subtilis and A. pontederiae occurred in the three habitats, whereas M. surinamicum occurred in salt marsh and rocky outcrop and M. amazonicum only in marisma. Temperature and pH were the most important environmental descriptors that significantly affected the density and biomass of shrimps.
Acesso aberto (Open Access)
Variação temporal do fitoplâncton e dos parâmetros hidrológicos da zona de arrebentação da Ilha Canela (Bragança, Pará, Brasil)
(Sociedade Botânica do Brasil, 2009-12) SOUSA, Eliane Brabo de; COSTA, Vanessa Bandeira da; PEREIRA, Luci Cajueiro Carneiro; COSTA, Rauquírio André Albuquerque Marinho da
Seasonal and nyctemeral variations of the phytoplankton and hydrological parameters were studied at a fixed station (00º46'37.2"S-046º43'24.5"W) situated in Canela Island (Bragança-Pará) in September and December, 2004 and in March and June, 2005. Subsurface water samples were taken for qualitative and quantitative phytoplankton studies and to determine chlorophyll a concentrations. Simultaneously physical and chemical parameters were measured: salinity, temperature, pH, dissolved oxygen and percent of oxygen saturation. A total of 64 taxa belonging to Cyanophyta (one taxon), Bacillariophyta (54 taxa) and Dinophyta (nine taxa) were identified. Chlorophyll a concentrations ranged from 4.67 mg m-3 (dry season), to 5.44 mg m-3 (rainy season) and follow phytoplankton densities, which were higher during the rainy period (mean values of 1,870 x 103 cell L-1). Phytoflagellates quantitatively dominated the local phytoplanktonic community followed by diatoms. Dimeregramma minor and Skeletonema sp. were abundant and ve