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... In fact, some of these beaches are overcrowded during vacation periods and extended holidays (Sousa-Felix et al., 2017), and subject to an increasing exploration (Szlafstein, 2012), resulting in a range of anthropogenic hazards (e.g. bacteriological contamination from sewage outfalls, litter pollution) (Sousa-Felix et al., 2017;Pereira et al., 2018). Another emerging environmental problem on many Amazonian beaches is the presence of multiple motor vehicles (Pereira et al., 2018;Santos et al., 2021a). ...
... bacteriological contamination from sewage outfalls, litter pollution) (Sousa-Felix et al., 2017;Pereira et al., 2018). Another emerging environmental problem on many Amazonian beaches is the presence of multiple motor vehicles (Pereira et al., 2018;Santos et al., 2021a). In fact, during vacation periods, multiple vehicles are driven onto some of the touristic beaches and serious problems have been recorded, including accidents and traffic jams Pereira et al., 2018). ...
... Another emerging environmental problem on many Amazonian beaches is the presence of multiple motor vehicles (Pereira et al., 2018;Santos et al., 2021a). In fact, during vacation periods, multiple vehicles are driven onto some of the touristic beaches and serious problems have been recorded, including accidents and traffic jams Pereira et al., 2018). In addition, especially during vacation periods, vehicles parking on the intertidal zone, are often trapped by the rapid rise of the tide Pereira et al., 2018). ...
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We report for the first time the effects of vehicle traffic and beachgoer trampling on macrobenthic communities of Amazonian sandy beaches. Sampling was performed during four consecutive months with different beach use intensity in 2017 (before, during vacation, and two months after the vacation period) on three contrasting beaches with regard to disturbance (Urban: Atalaia; Intermediate: Farol-Velho; and Protected: Corvinas) in the intertidal zone along two equidistant transects at seven equidistant sampling stations from the high-tide water mark to the swash zone. At each sampling station, four biological and sediment samples were randomly collected. Also, in each station, the sediment compaction was determined using a manual penetrometer. Physical sediment variables remained constant over time in all beaches, whereas differences were found in sediment compaction over the months. Macrobenthic community differences in density and richness among months were observed at Atalaia and Farol-Velho beaches. In contrast, Corvinas beach remained constant throughout the study period. Furthermore, the vulnerability of the polychaetes Thoracophellia papillata, Scolelepis squamata and Paraonis sp. indicates that they might be potential indicators of recreational activity impact
... Much of this coastline is sparsely populated or even uninhabited in such a way that most of beaches can be classified as natural (rural) or semi-natural ones, with some urban beaches in densely-populated areas. Anthropogenic pressures and conflicts accessed on the beaches include (i) the unregulated occupation of land, in particular in mangroves, and on dunes and cliffs, and (ii) the presence of cesspits, solid garbage and illegal sewage outfalls in the mangrove or intertidal zone, and on dunes (Szlafsztein, 2009;Pereira et al., 2018). ...
... The observed increased use of Amazon beaches which leads to an increase in the frequency and intensity of these conflicts (e.g., Pereira et al., 2014Pereira et al., , 2018, highlights the urgent need for the implementation of adequate coastal management plans for the Amazon littoral. In this sense some attempts, such as state and municipal coastal management programs, and the Promenade project, have been implemented, but have yet to produce satisfactory results (Szlafsztein and Sterr, 2007;Szlafsztein, 2012). ...
... A total of eight RESEXes are found in Pará, and they all play a fundamental role in the management of the space used by traditional populations, in particular fishing communities (Moreira and Silva, 2012). In recent decades, however, increasing pressure from a large number of stakeholders, with interest in the development of recreational activities has generated both social conflicts, such as the loss of the identity of traditional local populations, and environmental problems, including overcrowding, erosion, and contamination (Pereira et al., 2014(Pereira et al., , 2018. ...
... Sousa et al. (2017) O litoral no nordeste paraense é constituído por aproximadamente 15 grandes baías associadas à rios e igarapés. Além disso, praias estuarinas e oceânicas, extensas florestas de mangue e campos de dunas compõem a paisagem deste litoral (PEREIRA et al., 2018;SOUZA et al., 2019). Essas características naturais promovem um isolamento relativo da região, dificultando o acesso as praias e ao desenvolvimento do turismo costeiro. ...
... Contudo, o uso intensivo destas praias, pressão humana sobre os recursos naturais e a falta de planejamento urbano tem desencadeado significativos problemas socioambientais. Tais problemas têm afetado a costa local, alterando as condições naturais e prejudicando atividades recreativas e econômicas (SOUSA et al., 2017;PEREIRA et al., 2018). ...
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Esta pesquisa teve objetivo de identificar os problemas socioambientais nas principais praias oceânicas do litoral paraense (Pará, Amazônia, Brasil) e discuti-los com ênfase no planejamento, gerenciamento e desenvolvimento dessa região. As praias estudadas foram Ajuruteua (Bragança), Princesa (Maracanã), Atalaia e Maçarico (Salinópolis). Foram utilizados os métodos da Capacidade de Carga Recreacional (CCR) e DPSIR. Os parâmetros utilizados na avaliação da qualidade da água apresentaram-se insatisfatórios para as praias de Ajuruteua, Maçarico e Atalaia. A qualidade ecológica da praia da Princesa foi considerada excelente. A praia do Atalaia apresentou melhores índices de qualidades de serviços. A CCR apresentou diminuição na capacidade de todas as praias. A análise do DPSIR demonstrou o Estado das quatro praias. As pressões naturais e antrópicas observadas foram erosão, elevada precipitação, alta turbidez da água, a falta de planejamento para o desenvolvimento socioeconômico, uso e ocupação desordenado do solo, ausência de saneamento e ausência de gerenciamento costeiro e infraestrutura adequada. Os problemas socioambientais revelam que as praias do Atalaia e Ajuruteua são as mais impactadas. O Estado em que as praias se encontram sugerem que não houve planejamento para o desenvolvimento socioeconômico do litoral paraense e que as políticas públicas adotadas pelos municípios não estão sendo aplicadas.
... The Brazilian Amazon coast occupies a coastal strip between the Oiapoque River at Amapá State (5 • N, 51 • W) and the São Marcos Bay at Maranhão State (2 • S, 44 • W). Meteorological and oceanographic features are marked by high annual precipitation (up to 3300 mm), high temperatures (>20 • C) with low annual thermal variation, wide continental shelf (~330 km), macrotidal regime (ranging from 6 m to 12 m), extensive area of mangroves, fluvial discharge from dozens of estuaries, including that of the Amazon river, high sediment accretions, and high input of nutrients and organic matter [21,22]. The Amazon Region contains the largest river basin in the world, the Amazon River, which contributes to approximately 16% of freshwater discharged into the oceans [23]. ...
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Marine phycotoxins are organic compounds synthesized by some species of microalgae, which accumulate in the tissues of filter-feeder organisms such as bivalve mollusks. These toxins can cause acute intoxication episodes in humans, a severe threat to aquaculture and fisheries. In the State of Pará, Brazil, oyster farming has community, artisanal and sustainable bases, using mangroves as cultivation environment and seed banks. In small-scale production, there are often no established methods of safeguarding the health of consumers elevating the potential risks of shellfish poisoning outbreaks. Our study evaluated the presence of phycotoxins in oysters cultivated in five municipalities in the region of the Atlantic Amazon (Pará, Brazil) assessing the quality of the final product. We further evaluated the microalgae, water quality, and the spatio-temporal variation of physicochemical factors in the same area. Diatoms dominated the microalgae composition, followed by dinoflagellates, some of which are reported to be potentially toxic and producers of paralytic shellfish toxins. For the first time, we describe the occurrence of the potentially toxic dinoflagellate Ostreopsis sp. in the Amazon region. Furthermore, for the first time, toxins were detected in oyster farming in the northeast of the State of Pará, namely GTX2,3, STX, and dc-STX nevertheless, with nontoxic values. The identified toxins represent a potential threat to shellfish consumers.
... The intertropical convergence zone (ITCZ) influences the unimodal rainfall pattern (Santos Dos et al., 2020;Sá et al., 2022), acting directly on the trophic state of the estuary. During the dry season, the ITCZ moves to the Northern Hemisphere (>2 • N latitude), resulting in lower rainfall (usually below 100 mm per month) (Pereira et al., 2013;Pereira et al., 2018;Lefèvre et al., 2017;Asp et al., 2018). ...
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Modeling approaches are useful tools for assessing the general state of eutrophication and understanding the effects of multiple stressors on coastal ecosystems. Thus, we hypothesized that anthropogenic pressures and multiple stressors would increase the trophic state of macrotidal estuaries. Datasets from long-term (2012−2020) environmental and biological monitoring in the Itapecuru River estuary (IRE) were analyzed using the pressure-state-response (PSR) approach and nonlinear methods. Our results indicated a low dilution of nutrients and a moderate flushing potential of urban effluent (2150.94 ton year⁻¹) in the estuary. The estuary was consequently classified as being in a high trophic state, being susceptible to and suffering high estuarine pressure to develop eutrophic symptoms. The Assessment of estuarine trophic status (ASSETS) model indicates that eutrophication is seasonal and depends on climatic variation. La Niña events (2019–2020) contributed to chlorophyll-a (>40 μg L⁻¹) and orthophosphate (0.04 mg L⁻¹) concentrations, principally during periods of low river discharge. According to the GAM's model, brackish waters (salinity>10) with high temperatures (> 30 °C) and high dissolved oxygen (>4 mg L⁻¹) have more intense trophic conditions, especially in the mixing zone. The low dissolved oxygen (DO) levels (DO<3 mg L⁻¹) and high concentrations of chlorophyll-a in the seawater zone indicate that the lower portion of the estuary was the most susceptible. In addition, the random forest model selected salinity, DIP and Chl-a as the principal stressors that intensified eutrophication in the macrotidal systems. According to the ASSETS final ranking (worsen-high) for the next decade (2021−2031), the primary planned strategies should be to reduce anthropogenic contributions and improve trophic conditions in the IRE. From these results, the interactions and predictions of eco-hydrological effects could facilitate the characterization of future risks and the management of macrotidal estuarine systems.
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A problemática atual da produção e destinação inadequada de Resíduos Sólidos se tornauma ameaça devido ao tempo de persistência de seus componentes no meio, em especial ao ecossitema praiano.Este artigo tem o objetivo de compreender a dinâmica da distribuição dos resíduos sólidos na orla Ilha do Maranhão, situadano nordeste brasileiro e investigar os possíveis riscos ligados a fauna associada, com ênfase aoOcypode quadrata, um indicador de qualidade ambiental de praia bastante pesquisado em todo o mundo. Para tanto, amostras foram coletadas em 2 seções divididas em menor e maior fluxo antrópico, em 2 praias arenosas da ilha e em 2 períodos distintos, um chuvoso e o outro de estiagem. Os resultados mostraram uma predominância do plástico em relação aos outros materiais coletados nos períodos de chuva e de estiagem. Os processos de urbanização do litoral da ilha do Maranhão também mostraram influência sobre a frequência das tocas de O. quadratae sobre a dinâmica dos resíduos sólidos de forma geral, além de proporcionarem mudanças significativas no habitat natural das espécies estudadas afetando a sua abundância bem como as funções ecológicas que as mesmas desempenham
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The Ajuruteua beach (Braganca-PA) is formed by sandy barrier-beach ridges, consisting of well selected unimodal quartz fine sand. Regularly inunded for a macrotidal (6m), it's waves are spilling breakers, and the NE winds are dominant. 10 beach profiles was realizated in dry and wet periods, where it was divided in three sectors: I (SE), 11 (Central) e III (NW). The Sectors I and III shows a smooth ridge and runnel system, that is filled in the wet period. The Sector II shows a flat profile in both periods. The Ajuruteua beach have dissipative characteristics, shows two morphological states. In the first (wet period), in function of strong spring tides and waves, the sediments are eroded and develop 3m high beach scarps on the foredunes (Sector II), with 25m of retreat. In the second (dry period), the sediments eroded are reincorpored to the beach, through sand ridges migration in direction of the beach, and the formation of a smooth ridge and runnel system. According with the results, the dynamics agents who acts in the morphological conditionants of Ajuruteua beach are macrotidal processes associated to strong waves.
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The Brazilian equatorial macrotidal sand beaches present peculiar meteo-oceanographic characteristics. The aim of this study was to understand the morphodynamic processes of the Vila dos Pescadores beach in two different sectors (a sheltered/bay sector – P1 and an exposed/marine sector – P2). To evaluate the morphological changes, transects were bimonthly monitored between February/2006 and February/2008. Sediment samples were simultaneously collected to the topographic leveling in both profiles to determine the sedimentary cover. Additionally, wind and current intensity and direction were also measured and analyzed to understand the local coastal dynamics. Winds blew stronger in the second semester mainly in the P2 profile. The most important alterations on beach's morphology (erosion) were observed during the equinoctial spring tide periods, when the tidal currents attain the highest intensities, although a general tendency of stability was observed, considering the annual balance. The sediment cover was mainly comprised by fine sand, however in the P1 profile the presence of very fine sand and mud was also observed. Prior to the last decades, the village presented serious erosive processes with the partial destruction of mangrove areas, dunes and buildings. Recently, the formation of a sand bar in front of the village has contributed to the sediment supply and beach stabilization, therefore buildings destruction was not verified during the studied period. The results suggest a complex interaction between winds, tides, waves and tidal currents in the local beach morphodynamics, with an important seasonal component.
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The metropolitan area of São Luis represents one of the most densely-populated areas of the Amazon Coast, but the recreational use of its beaches has been prohibited by the local authorities due to the poor quality of the water. The present study aimed to estimate the Recreational Carrying Capacity (RCC), water quality and the perception of beachgoers at four beaches during peak visitation periods. Each of the four beaches was surveyed over a three-day period (Friday-Sunday) in July 2009. In each survey, the number of people present along a pre-established transect was counted every hour between 08:00 h and 18:00 h. Samples of the water were taken between 07:00 h and 19:00 h, and a sample of beachgoers were interviewed using questionnaires. Peak visitation times were similar at the four beaches, and Saturday and Sunday were the most popular days. Zones 1 (landward) was the most visited, while the use of zone 2 (intertidal zones) was influenced by tidal condition and the zone 3 (subtidal zone) was affected by poor water quality. The recreational carrying capacity of each beach was influenced by the day of the week, insolation, tide levels, and bacteriological contamination. However, the majority of the beachgoers interviewed during the study seemed to enjoy the beaches. Despite measures taken by the local authorities, such as the shutting down of some of the sewage outlets, the problem of poor water quality has not been resolved, and the beaches were still improper for bathing as of July, 2010.
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This study took place at Princesa Beach, located in an area of environmental protection on the Amazon coast of Brazil. The aim was to evaluate the impact of natural processes and human activities on this macrotidal beach, and provide local authorities with guidelines for the implementation of a coastal management program. Data on social and natural variables were collected between November, 2008, and August, 2010. All amenities on the beach were identified and georeferenced using a GPS in August, 2010. Four campaigns of over 25 hours duration were conducted during spring tide periods November, 2008, and March, June, and September, 2009 for the collection of hydrodynamic and hydrologic data. Motorized vehicles are prohibited on the island. The waterfront of Princesa beach is characterized by the presence of a small number of buildings. The beach receives large numbers of visitors only during July and certain bank holidays. The recreational consumption of drugs constitutes the island's main social problem. Climatic and hydrological conditions were the main factors responsible for the high water turbidity and dissolved oxygen levels, and elevated concentrations of chlorophyll a and dissolved nutrients. The study area was not adversely affected by thermotolerant coliform levels. In order to guarantee the environmental integrity of the beach over a long term, the authors suggest: (i) the construction of an adequate public sanitation system, (ii) creation of garbage recycling programs (to reduce refuse in the dunes), (iii) incentives for the development of ecotourism programs, (iv) regulation of land use, and (v) intervention for the control of recreational drug use.
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The conservation and management of the coastal zone of the Amazon region demands special attention, given the richness of its natural resources. The aim of the present study was to evaluate the impact of natural events and human activities on Atalaia beach, and to develop guidelines for the implementation of coastal management programs. Data were collected between November, 2008, and November, 2010. Four sets of variables were assessed: (i) physical variables (climatology and hydrodynamics), (ii) hydrological variables (water temperature, salinity, pH, turbidity, dissolved oxygen and nutrients, chlorophyll-a, and thermotolerant coliform levels), (iii) urban development and (iv) spatial distribution of services and infrastructure. The results indicate that climate and hydrodynamical conditions were the main factors responsible for fluctuations in water salinity, turbidity, dissolved oxygen, dissolved nutrients, and chlorophyll-a concentrations. The discharge of untreated domestic sewage was responsible for bacteriological contamination, although the rapid turnover of the high-energy hydrodynamic environment limited contamination by thermotolerant coliforms. This high hydrodynamic energy, primarily during the equinoctial spring tides, and the lack of urban planning, nevertheless generates other problems, such as coastal erosion. The following measures were recommended: (i) rationalize sewage disposal; (ii) removal of cesspits from the intertidal zone and dunes to avoid contact with groundwater and tides; (iii) implementation of a public sanitation system; (iv) continuous monitoring of water quality for the control of bathing areas, and (v) stricter urban planning and regulation to minimize pressures on coastal environments.
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Two beaches located near the mouth of estuaries in contrasting environments were analyzed in the present study. Sao Luis' beaches are located on the Amazon coast (Brazil), a coast dominated by tidal processes. Jimmy's beach is located on the SE coast of Australia, a wave-dominated coastal environment. The aim of this paper is to compare the evolution of the two areas under different wave-tide conditions. Hydrodynamic and topographic surveys were undertaken during seasonal conditions in both areas. The most obvious differences are the tide ranges, incident waves and rainfall patterns, together with the sources and availability of sediments. It appears also that anthropogenic changes often override natural change at both locations. The beaches of Sao Luis are undergoing erosion, mainly in the outer section of the bay, while the inner-middle sections often register accumulation in the wet season (river supply, inner section) and in the dry season (aeolian dune supply, middle section). Jimmy's beach is a sediment-starved environment that undergoes continuous erosion. Sources of sediment are limited, but they seem to be linked to the dynamics of the outer parts of the flood-tide delta that provides sediment that is transported into the estuary by severe and extreme storms. This paper shows that high-energy events do not necessarily cause major erosion to all areas, which normally exist under low-energy conditions. In fact, high energy events seem to have the capability of activating sediment sources that are not normally connected to the sediment budget of the area, thus bringing 'new' sediment into the system.
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According to the World Mangrove Atlas, this ecosystem represents 8% of the world’s coastline and one quarter of the tropical coastal zone shoreline, embracing 181,077 km2. The aim of this work is to map and to quantify the extension of macrotidal mangroves along the northeastern Par´a and northwestern Maranh˜ao coasts, here named as Amazon Macrotidal Mangrove Coast (AMMC). The identification of mangrove areas and their quantification were carried out using Landsat-7 ETM+ images acquired in 1999 and 2000 and a geographic information system (GIS). The integration of remote sensing data, geological and oceanographic data allowed the recognition of five geomorphologic sectors, representing a total mangroves area of 7.591 km2. This area represents the largest continuous mangrove belt in the world and constitutes 56,6% of mangroves in Brazil. Prioritary measures for Amazon mangrove conservation must be taken and research to enhance understanding of this complex and important ecosystem must be supported and developed.
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Orbital remote sensing data were assessedfor mapping of the main geomorphologicaland vegetation units of the Braganapeninsula (North Brazil), which belongs toa vast though sparsely mapped mangrovecoast. Wide wetland environmentscharacterize the region with extremevariations in extension, temporalevolution, and spatial complexity. Thiswork was based on different digitalprocessing techniques separately applied toLandsat TM and RADARSAT-1 images. Inaddition, both data were merged on apixel-to-pixel basis using algorithms,which rendered an enhancement of thecoastal landforms and a betterdiscrimination of wetlands and landformtypes. The interpretation of the integratedproduct, aided by field validation, made itpossible to significantly extend existingmapping. Nineteen geobotanical units wereidentified: estuarine channels, submergedsand banks, sandflats, old estuarinesandbanks, mudflats, ebb-tidal deltas,barrier-beach ridges, coastal dunes,chenier sand ridges, young intertidalmangroves, intertidal and supratidalmangroves, outer and inner marshes, fluvialflood plains, coastal plateau, degraded andregenerated mangroves, and an artificiallagoon. The digital integration of Fine RADARSAT-1 and Landsat TM data sensitivelyhighlighted geobotanical coastal features,providing a useful tool for a synopticanalysis of their natural and man-drivenchanges.
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A mangrove ecosystem shows close links between geomorphology and vegetation assemblage. In addition, the vegetation can change over time as landforms can accrete or erode, which is a direct response to coastal sedimentary processes. This demonstrates that significant changes can occur on short time scales and mangroves provide an excellent register of these modifications. Therefore, mangrove morphology and sedimentation are good indicators of interactions between relative sea level changes, coastal processes and sediment supply. These interactions are responsible for landward migration of the shoreline (erosion) and seaward migration of the shoreline (accretion), which is possible to detect from multi-date satellite data and field observations. Mangroves are one of the best geo-indicators in global coastal change research and they are an excellent procedure to detect and quantify coastal modifications.
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The 1500 km-long coast of South America between the Amazon and the Orinoco river mouths is the world's muddiest. This is due to the huge suspended-sediment discharge of the Amazon River (106 × 754 tons yr− 1 ± 9%), part of which is transported alongshore as mud banks. Mud-bank formation is controlled by the physical oceanography of the continental shelf seaward of the Amazon River mouth, an initial seafloor storage area for much of the suspended sediment discharged from the river. In this area, rapid and sustained fluid-mud concentration and trapping are associated with fresh water–salt water interaction and estuarine front activity on the shelf due to the enormous Amazon water discharge (ca. 173,000 m3 s− 1 at Obidos, 900 km upstream of the mouth). Fluid mud is transported shoreward and then along the coasts of the Guianas by a complex interaction of wave and tidal forcing, and wind-generated coastal currents. The mud banks, which may number up to 15 or more at any time, are up to 5 m-thick, 10 to 60 km-long, and 20 to 30 km-wide, and each may contain the equivalent mass of the annual mud supply of the Amazon. As the banks migrate alongshore, their interaction with waves results in complex and markedly fluctuating shorelines that are associated with space- and time-varying depositional ‘bank' phases and erosional ‘inter-bank' phases. Bank zones are protected from wave attack as a result of wave-energy dampening by mud, and undergo significant, albeit temporary, coastal accretion accompanied by rapid mangrove colonization. The dampening of waves in bank areas as they propagate onshore is accompanied by the shoreward recycling of mud, commonly in the form of individual mud bars. These bars progressively undergo desiccation and consolidation, and thus constitute a major pathway for rapid and massive colonization by mangroves. Erosion by waves propagating across relatively mud-deficient shoreface zones in inter-bank areas can lead to muddy shoreline retreat rates of tens of metres to several kilometres over a few months to a few years, accompanied by massive removal of mangroves. Notwithstanding the higher incident wave energy on inter-bank shores, inter-bank shorefaces are permanently muddy due to the pervasive influence of the Amazon muddy discharge. Inter-bank and transitional bank-to-inter-bank phases are associated with both periodic sandy chenier formation and extreme forms of rotation of rare headland-bound sandy beaches. The high mud supply from the Amazon has been the overarching geological control on the Quaternary evolution of the northeastern South American coast, having led to the growth of a muddy shelf clinoform at the mouth of the Amazon and more or less important progradation throughout this coast. Net progradation reflects an imbalance in favour of deposition during each mud-bank–inter-bank cycle. The high mud supply has presumably blanketed shelf sand deposited by smaller rivers during eustatic lowstand phases. The shelf clinoform structure at the mouth of the Amazon and the muddy coastal progradation throughout the coast of the Guianas and into Venezuela provide analogues of the geological record on muddy shorefaces.
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Synthetic Aperture Radar (SAR) images are being used more extensively than ever before for geoscience applications in the moist tropics. In this investigation, a RADARSAT1-1 C-HH SAR image acquired in 1998 was used for coastal mapping and land-cover assessment in the Bragança area, in the northern Brazil. The airborne GEMS 1000 X-HH radar image acquired in 1972 during the RADAM Project was also used for evaluating coastal changes occurring over the last three decades. The research has confirmed the usefulness of RADARSAT-1 image for geomorphological mapping and land-cover assessment, particularly in macrotidal mangrove coasts. It was possible to map mangroves, salt marshes, chenier sand ridges, dunes, barrier-beach ridges, shallow water morphologies and different forms of land-use. Furthermore, a new method to estimate shoreline changes based on the superimposition of vectors extracted from both sources of SAR data has indicated that the shoreline has been subjected to severe coastal erosion responsible for retreat of 32 km² and accretion of 20 km², resulting in a mangrove land loss of almost 12 km². In an application perspective, orbital and airborne SAR data proved to be a fundamental source of information for both geomorphological mapping and monitoring coastal changes in moist tropical environments.
Article
The purpose of this paper is to determine the Recreational Carrying Capacity of three estuarine beaches (Colares, Marudá and Murubira) on the Amazon coast of Brazil, based on the combined assessment of natural conditions and visitor facilities. In the final analysis, the carrying capacity of Colares beach was estimated to be 1089 visitors per day, and that of Murubira beach, 238 visitors per day. At Marudá beach, however, the inadequate quality of the water resulted in an RCC of zero, indicating that the beach should not be visited for recreational use. The results of this study may provide a valuable diagnostic tool for the development of future state and municipal coastal management programs. We believe that the procedures adopted in this study are applicable to other estuarine beaches on the Amazon coast, as well as in other estuarine beaches elsewhere with similar natural characteristics.
Chapter
Amazon coast is a vast and complex estuarine–marine system with highly dynamic coastal environments driven by an abundance of sediment reworked by fl uvial, tidal and wave processes. The coast of Pará occupies the eastern Amazon Gulf and is more than 2000 km long, with more than 400 sandy beaches. It can be divided into fi ve coastal sectors: the Amazon river-distributary coast; the north coast of Marajó Island; the west and east coasts of Marajó Bay; and the highly indented eastern barrier island coast between Marajó and Gurupi bays. This chapter will examine the eastern Pará coast, between Belém in Marajó Bay and Gurupi Bay, a macro to mega-tidal coast dominated by tide-modifi ed and tide-dominated sand beaches. There is however considerable spatial and temporal variability in beach state, dependent on the amount of nearshore sheltering by inter to sub-tidal sandbanks, with tide-modifi ed beaches (3 < RTR < 15) on the more exposed sections and tide-dominated (RTR > 15) on the more sheltered sections, together with tidemodifi ed beaches at high tide and tide-dominated at low tide. The impact of this tidal modulation on wave energy and beach morphodynamics is examined on three beaches, together with their associated beach hazards. These are then combined with seasonal tourism population to assess the level of risk. The large seasonal beach population coupled with unplanned beach development generates addition hazards including eroding buildings, traffi c congestion and accidents on some beaches, and sewerage and litter pollution. Coastal planning and regulation is urgently required for this coast to enable it to develop a safe and sustainable tourist industry and to reduce the beach hazards and risk.
Chapter
The 1200 km of coastline of Maranhão is the second longest amongst Brazilian states, and is located just south of the equator between the Gurupi River and the Parnaíba Delta. Maranhão represents a transition zone from the tide-dominated Amazon-Pará coast to the more wave-dominated Ceará coast. Morphologically, this coast can be divided in three provinces: (i) Western coast – heavily indented macro-tidal coast composed of funnel-shaped, tide-dominated estuaries, separated by low mangrove-dominated peninsulas capped by dynamic barrier islands and tide-modifi ed to tide-dominated beaches; (ii) Central coast – occupied by the four arms of the funnel-shaped, tide-dominated Maranhão Gulf, with tide-modifi ed and tide-dominated beaches, occupying most of the more exposed outer estuarine shoreline; and (iii) Eastern coast – a relatively straight coast with tides decreasing towards the east from 7 to 3 m, resulting in wave-dominated beaches backed by extensive Holocene and Pleistocene trasgressive dune fi elds. In the Central Maranhão Gulf is São Luís, the most urbanized zone on the Maranhão coast. Its tide-modifi ed beaches present many beach hazards to the beachgoers. In addition, the beach quality, considering natural (climatic, morphodynamic, and hydrological processes) and social (occupation of the land and types of services and infrastructure) conditions has been adversely affected in different ways. Local beaches are being increasingly occupied by urban development, which is affecting the equilibrium of depositional systems, primarily through the occupation of dunes and cliffs. In addition, the local water quality has been affected by the lack of an adequate public sanitation system and the presence of numerous illegal sewers, which contribute to the elevated bacteriological contamination. The lack of local urban planning has caused serious social and environmental problems and effective management plans for this sector of the Amazon coast are urgently needed.
Article
Equatorial sandy beaches have considerable tourism potential, while morphological studies, which are indispensable for the development of effective beach management strategies, are scarce. This paper analyses beach processes, morphodynamic state and change, and associated physical hazards and risks, in relation to spatial and temporal oscillations in meteorological and hydrodynamic variables on several macro-tidal Amazon coast sandy beaches. These beaches are located in macrotidal areas with tide ranges between 4 and 6 m and exposed to waves with Hs up to 1.5 m. In addition, they are characterized by low gradients, fine sand and an intertidal width of 200–400 m at low spring tide. Because of the tidal modulation the beaches transform from wide bare tidal flats to rapidly inundating flats with increasing wave and tidal currents velocities and wave height, as the tide rises. These conditions trap beach users and their vehicles leading to numerous accidents and some fatalities. In addition a range of beach and water activities (vehicles, kite and wind surfing) bring users into conflict and risk. At present coastal and beach management plans are non-existent. There is an urgent need to implement beach management practices which allocate beach usage, educate and warn beach users of the hazards, provide first aid and to employ lifeguards to maintain beach safety, enforce areas of usage and effect rescues, particularly during the vacation periods.
Article
Because variations in the zooplankton community are common in macrotidal estuaries, the composition and density of these organisms in the estuary of the Paracauari River, an equatorial macrotidal system of the Amazon coastal zone, was studied during spring and neap tides to 'evaluate fluctuations related to variations in the physical and chemical characteristics of the water. Significant differences between tidal periods were recorded for salinity, pH, and dissolved oxygen. Phosphate concentrations were significantly higher in the spring tide. In all, 34 taxa were identified, with the Cirripedia dominating in both tides. Total density was highest in the spring tide (1871.6 +/- 1248.4 individuals m(-3)), whereas chlorophyll a was lowest (10.46 +/- 3.48 mg m(-3)). Diversity was also higher in the spring tide. Multivariate analyses indicated the formation of two distinct groups representing the spring and neap tides. The zooplankton comprised mainly estuarine and coastal species. Oithona oswaldocruzi, Paracalanus quasimodo, and Acartia tonsa were the most common, and their density was related directly to tidal oscillations.
Article
A Multidisciplinary Amazon Shelf SEDiment Study (AmasSeds) investigated the oceanic processes near the mouth of the Amazon River in order to understand the fate of its enormous discharge of water, solutes and particulates. In addition to receiving a large fluvial discharge, the continental shelf near the Amazon mouth is situated on the equator and experiences an extremely energetic physical regime. As such, it represents an end member in the spectrum of coastal marine settings, with regard to latitude, energy and discharge. The oceanic processes occurring on the Amazon shelf reflect these environmental characteristics.
Article
The Amazon shelf is subject to energetic forcing from a number of different sources, including near-resonant semi-diurnal tides, large buoyancy flux from the Amazon River discharge, wind stress from the northeasterly tradewinds and strong along-shelf flow associated with the North Brazil Current. Although the large volume of river discharge produces a pronounced salinity anomaly, the water motions on the shelf are dominated by the other forcing factors. Tidal velocities of up to 200 cm s−1 are generally oriented in the cross-shelf direction. Tide-induced mixing influences the position and structure of the bottom salinity front that separates the well-mixed nearshore region from the stratified plume. High concentrations of suspended sediment trapped along the frontal zone increase the stability of the tidal boundary layer and thus reduce the bottom stress. At subtidal frequencies, motion is primarily along-shelf toward the northwest, both in the plume and in the ambient, high-salinity water of the outer-shelf. The plume is generally 5–10 m thick, with a salinity of 20–30 psu. The along-shelf velocity within the plume varies as a function of the along-shelf wind stress. This variability results in large temporal variations in plume structure and freshwater content on the shelf. The net northwestward motion of the Amazon plume and of the ambient shelf water appears to be the result of a large-scale pressure gradient associated with the North Brazil Current system.
A socioeconomic and natural vulnerability index for oil spills in an Amazonian harbor: a case study using GIS and remote sensing
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Tábuas de maré para o fundeadouro de Salinópolis
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10. Limitations, attractions, and natural and anthropogenic hazards found on rural, semi-urban and urban Amazon beaches
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Fig. 10. Limitations, attractions, and natural and anthropogenic hazards found on rural, semi-urban and urban Amazon beaches.
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Water quality at touristic beaches on the Amazon coast
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Sousa, R.C., Pereira, L.C.C., Costa, R.M., 2013. Water quality at touristic beaches on the Amazon coast. J. Coast. Res. 65, 1057-1062.
Estuarine beaches of the Amazon coast: environmental and recreational characterization
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Sousa, R.C., Pereira, L.C.C., Jiménez, J.A., 2016. Estuarine beaches of the Amazon coast: environmental and recreational characterization. J. Coast. Res. 70 (1), 705-709.
Development projects for small rural communities in the Brazilian Amazon region as potential strategies and practices of climate change adaptation
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Szlafstein, C.F., 2012. Development projects for small rural communities in the Brazilian Amazon region as potential strategies and practices of climate change adaptation. Mitig. Adapt. Strateg. Glob. Change 19, 143-160.
Tidal modulation of moderate wave energy on a sandy tidal flat on the macrotidal amazon littoral
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Trindade, W.N., Pereira, L.C.C., Vila-Concejo, A., 2016. Tidal modulation of moderate wave energy on a sandy tidal flat on the macrotidal amazon littoral. J. Coast. Res. SI75, 487-491.