Navegando por Assunto "Mangrove"

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Acesso aberto (Open Access)
Análise espaço-temporal dos manguezais degradados de Bragança, com base em imagens de satélite e modelos de elevação digital
(Universidade Federal do Pará, 2022-02-22) MOLANO CÁRDENAS, Sergio Mauricio; COHEN, Marcelo Cancela Lisboa; http://lattes.cnpq.br/8809787145146228
The Bragança Peninsula occurs at the northern littoral of Brazil, in the state of Pará. It is characterized by the largest continuous mangrove belt in the world. The construction of the PA- 458 road in the ‘70s changed the hydrodynamics of the peninsula, causing the degradation of a considerable portion of the mangroves in the central region of the peninsula. Recently, degraded areas are being colonized by mangrove trees, mainly by the Avicennia germinans specie. This study intends to identify changes in the degraded areas of the tidal flats in topographically higher sectors during the last 35 years. To reach that objective, we used the following techniques: a) manual mapping of the degraded areas with mid spatial resolution satellite imagery; b) object-based classification of the degraded areas and mangrove species, using high spatial resolution satellite imagery; c) photogrammetry of drone imagery; d) digital elevation models; and e) topographic validation with theodolite and GNSS GPS “Antenna Catalyst”. From 1986 to 2019, there was a reduction in the degraded areas of 247.96 ha according to the mid-resolution “dataset” quantification. However, high-resolution data showed a reduction in the degraded areas of 211.65 ha between 2003 and 2019. The degraded areas quantification presents fluctuations in the regeneration trend; it is related to significant climatic phenomena such as “El Niño” and “La Niña”, accompanied by periods of drought and high rainfall, respectively. Overall accuracy and Kappa index values for the high-resolution data generally exhibited values above 0.9. Producers’ and users’ accuracy and Kappa per class values showed the difficulties separating mangrove species due to the lack of radiometric resolution of the analyzed images. The digital terrain model representing the tidal flat showed two topographically differentiated regions in the degraded areas, separated by the PA-458 road, which are mainly influenced by the Caeté’s and Taperaçú’s characteristics. This same difference was found in the vegetation height model, where the largest trees are located toward the SE side of the road, reaching 25 m, while at the NW side of the road, the tree heights oscillated mainly between 5 and 15 m. The sea-level rise specifically controls regeneration rates. This relocated the intertidal zone to topographically higher areas, increasing tidal flushing processes, essential for the mangrove forests development.
Acesso aberto (Open Access)
Crescimento de mudas de mangue sob diferentes níveis de sombreamento na península de Ajuruteua, Bragança, Pará
(Instituto Nacional de Pesquisas da Amazônia, 2013-09) LOPES, Elaine Cristina; ARAÚJO, Erneida Coelho de; COSTA, Rejane Silva da; DAHER, Rogerio Figueiredo; FERNANDES, Marcus Emanuel Barroncas
The purpose of this study was to evaluate the influence of different levels of shading on the development of seedlings of three mangrove species (Avicennia germinans (L.) Stearn., Rhizophora mangle L. and Laguncularia racemosa (L.) Gaertn. f.). The experiment was conducted at the community of Tamatateua, Ajuruteua peninsula, Bragança, PA, Brazil. For seedling production, the propagules and seeds of the mangrove species were planted in polyethylene bags (17 x 27 cm), filled with a typical mangrove substrate. The seedlings of the three species were grown under full sun (0), 30% and 60% shading, in a completely randomized design, a 3 x 3 factorial (three species and three shading levels), with eight seedlings per replication. After nine months under shading, plant samples were taken. The variables evaluated were: the shoot/height ratio, stem diameter, shoot dry matter, stem mass, root dry matter, total dry mass matter and morphological indices. Growth of seedlings of R. mangle occurred at all light levels. Seedlings of A. germinans grew faster at full sun and at 30% shading. Whereas, seedlings of L. racemosa were able to grow at 30 and 60% shading, but they also grew faster at full sunlight.
Acesso aberto (Open Access)
Os efeitos dos manguezais e das intervenções humanas na dinâmica sedimentar das praias de SalinópoliS, PA
(Universidade Federal do Pará, 2025-03-07) PÉREZ MARTINEZ, Julián David; COHEN, Marcelo Cancela Lisboa; http://lattes.cnpq.br/8809787145146228
Salinópolis, on the coast of Pará, has become an important tourist hub, expanding its infrastructure along the coastal zone. This area is considered sensitive to sea-level rise. Therefore, identifying the area most vulnerable to coastal erosion is extremely important, especially due to the growth of coastal urban areas, which can interfere with sediment balance, intensifying erosion processes. This master's thesis aims to identify the effects of mangroves and coastal urban expansion on sediment balance along the beaches of Salinópolis. This study was carried out through a spatio-temporal analysis based on satellite (2003 – 2023) and drone data (2019-2024). The data revealed that the urban area expanded (627 ha), while the mangrove area fluctuated, increasing from 3630 ha to 3889 ha between 2003 and 2023. Erosion was identified along the beaches, particularly at Praia do Farol Velho (erosion = 432,625 m³, sedimentation = 217,259 m³). Praia do Atalaia (erosion = 115,415 m³, sedimentation = 462,630 m³) and the Maçarico/Corvina beaches (erosion = 640,389 m³, sedimentation = 801,670 m³) showed a trend of sediment accumulation. Erosion has predominantly occurred in the lower intertidal zone, while sedimentation has occurred in the supratidal zone and the upper intertidal zone. Residences, particularly in Farol Velho, may accentuate this process and Praia do Atalaia, which are currently located in the intertidal and supratidal zones in front of the mangroves. The walls built to protect these residences from waves and current action have also functioned as a barrier to retain sediments at the upper intertidal/supratidal transition. In much of Praia do Farol Velho, without these walls, there has been erosion in the intertidal zone, with a retreat of the coastline by about 100 meters between 2009 and 2023. However, the Maçarico/Corvina beaches have mangroves in front of the urban infrastructure, with sediment accumulation predominantly in the supratidal zone and the upper part of the intertidal zone. Human interventions on these beaches have not impacted the sedimentary dynamics until 2023. This beach provides a good example of how coastal infrastructure projects should be planned, using mangroves as protection against the action of waves and currents. However, the construction of beach access walkways in 2024 altered the hydrodynamic flow of a tidal channel, trapping tidal waters and creating muddy intertidal zones with porewater salinities close to 70 ‰. This process has already killed approximately 7 ha of mangrove. These data provide valuable insights to guide more efficient public and private investments, avoiding construction in high-risk areas or those that harm the mangroves, offering crucial information about coastal erosion and its impacts on urban infrastructure in the beaches of Salinópolis, especially in the face of sea-level rise.
Acesso aberto (Open Access)
A evolução dos manguezais nos litorais Nordeste e Sul brasileiros durante o Holoceno
(Universidade Federal do Pará, 2020-09-30) FREIRE, Neuza Araújo Fontes; COHEN, Marcelo Cancela Lisboa; http://lattes.cnpq.br/8809787145146228
It is possible that climate changes and sea level fluctuations (allogenic processes) are and will cause major changes in mangrove dynamics. However, other driving forces may be significantly affecting this system. Distinguishing allogenic and autogenic influence on mangroves is a challenging question, because mechanisms related to the natural dynamics of depositional environments (autogenic processes) have strong influences on the establishment and degradation of mangroves. Thus, impacts on mangroves caused by autogenic processes may be erroneously attributed to allogenic mechanisms. Therefore, it is imperative to identify the ‘fingerprint’ of global changes in modern mangrove dynamics. This thesis integrates palynological, geochemical, sedimentological data, 14C dating of sedimentary organic matter, geomorphological and vegetation data in order to evaluate the influence of autogenic and allogeneic processes on Brazilian mangroves during the Holocene. Tropical estuaries from Rio Grande do Norte and southern Bahia, and subtropical estuaries in northern and southern Santa Catarina estates with different climatic, geomorphological and oceanographic characteristics were studied. The Relative Sea-Level (RSL) along the Rio Grande do Norte reached modern level and stabilized at about 7,000 cal yr BP, allowing the mangrove establishment at the edges of the Ceará-Mirim River estuary until the nowadays. However, changes in the spatial distribution of mangroves have occurred since then due to channels dynamics in the region (autogenic processes). Considering the mangroves of the Jucuruçu River in southern Bahia, their horizontal and vertical distribution were controlled by the interactions of the changes in the RSL and fluvial discharge. Therefore, the dynamics of these estuarine mangroves during the Holocene was mainly controlled by changes in sea level and precipitation that affected fluvial discharge. These allogeneic mechanisms were the main drivers of the dynamics of these mangroves. However, during the last 600 years, factors intrinsic to the depositional system gained relevance by controlling the establishment and migration of mangroves by deposition and erosion of muddy tidal flats, abandonment and reactivation of channels (autogenic processes). In the case of Santa Catarina mangroves, the RSL rise up to the middle Holocene was decisive for the establishment of tidal flats appropriate for the expansion of saltmarshes. However, mangroves did not tolerate the Holocene low temperatures in the southern littoral of Santa Catarina. The pollen data indicate the establishment of mangroves with Laguncularia around 1,700 cal yr BP, followed by Avicennia and lastly Rhizophora trees, a cold less tolerant genus, around 650 cal yr BP in São Francisco do Sul, north of Santa Catarina. The mangroves of Laguna, south of Santa Catarina, composed of Laguncularia and Avicennia, were established in the current southern limit of the South American mangroves only in the last decades. No evidence was found for the presence of mangroves in Laguna during the Holocene. The establishment of these mangroves in the region probably started during the Anthropocene, as a consequence of the increase in minimum winter temperatures in southern Brazil. Considering changes in precipitation rates over drainage basins that feed mangrove estuaries, as well as trends in RSL rise and temperatures until the end of the 21st century, tropical estuarine mangroves will likely migrate to higher topographically sectors in the interior of the river valleys, where its extension will depend on the volume of river discharge interacting with the RSL rise. Subtropical mangroves are expected to expand to more temperate zones as minimum winter temperatures increase. This process should cause an increase in the diversity of mangrove species, such as the introduction of the Rhizophora genus in the current southern limit of the mangroves, positioned in Laguna-SC. However, in the case of high rates of RSL rise, the relatively new subtropical mangroves are also expected to migrate to topographically higher sectors of the coast.
Acesso aberto (Open Access)
Reconstituição paleoambiental da vegetação costeira na foz dos rios Santa Maria da Vitória e Jucu durante o holoceno médio e tardio, Estado do Espírito Santo, Brasil
(Universidade Federal do Pará, 2025-03-13) PANTOJA, NISYA ROBELLY CARDOSO; FRANÇA, Marlon Carlos; http://lattes.cnpq.br/8225311897488790; https://orcid.org/0000-0002-3784-7702
Climate and sea level changes may have caused significant alterations in coastal morphology and mangrove distribution on the central coast of Espírito Santo State, Brazil. Therefore, this study aims to identify the dynamics of coastal vegetation during the middle and late Holocene, in the Santa Maria da Vitória and Jucu rivers. For this purpose, 14C dates, sedimentary data and pollen data were used, obtained from two sedimentary cores, called RSMV (340 cm) and JUCU (190 cm). During the middle Holocene, around 7245-7368 cal years BP, the relative sea level (SSL) was above the current level, resulting in the development of mangroves in the RSMV core region. However, around 2699-2787 cal years BP, with the regression of the SSL, the mangrove area moved to topographically lower regions. Another determining factor for the reduction of these areas during this period to date was human intervention. In the JUCU core region, mangrove forests were identified between 2188-2332 cal yr BP, initially colonized by Laguncularia. Thus, in this context, the dynamics of vegetation and sediments are associated with fluctuations in relative sea level and climate change throughout the Holocene.
Acesso aberto (Open Access)
Os saberes tradicionais dos pescadores de caranguejo-uçá e o manguezal: o caso de Tamatateua Bragança - Pará, costa Amazônica brasileira
(Universidade Federal do Pará, 2019-12) OLIVEIRA, Francisco Pereira de; SOUZA, Gamaliel Tarsos de; SILVA, Klayton Luiz Campelo; FERNANDES, Marcus Emanuel Barroncas
This study focuses on the empirical knowledge and environmental perceptions of Uçá crab (Ucides cordatus) fishermen from the Tamatateua region, municipality of Bragança, northeast of Pará. The main objective is to describe the fishermen's traditional knowledge on this resource focusing on the ecological knowledge from their perceptions and close relationship with the mangrove ecosystem. used the qualitative research approach, in which the technique and the research instrument were carried out using interviews from a questionnaire designed with semi-structured questions, respectively. Data collection took place between 2017 and 2018, with 14 (fourteen) fishermen of Uçá crab, aged between 22 and 62 years, in which the analytical process made use of content analysis. The results demonstrate that the fishermen have elaborated ecological knowledge about the Uçá crab specimen, as well as the natural and environmental phenomena. They perceive the connection between the human being and the mangrove as a synonym of food, marketing, culture, religiosity, among others, which, in some way, directly influence the knowledge passed on from generation to generation through non-formal and informal education. It was also found that the management of the Uçá crab resource is due to the learning process that occurs daily between kinship (father, son, grandson, uncles and others), as well as in the process and socialization (sharing) between friends of the “ mangrove". On the other hand, it was identified that even using predatory practices and arts, such as the hook, the fishermen recognize them as such, but reveal the idea of maintaining the resource when arguing about the respect in the reproduction periods of the specimen.