Anabela Oliveira

Instituto Hidrográfico | IH · Marine Geology

Introduction The production of resting cysts is a key dispersal and survival strategy of many dinoflagellate species. However, little is known about the role of suspended cysts in the benthic nepheloid layer (BNL) in the initiation and decline of planktonic populations. Methods In September 2019, sampling of the dinoflagellate cyst community at di...

This report summarizes current threats to the Tagus estuary and adjacent ecosystems, presented in Lisbon in June 2021, and prioritizes actions to maintain or improve ecosystem services for a densely populated area close to the deep ocean.

Low-power wide-area networks are extending beyond the conventional terrestrial domain. Coastal zones, rivers, wetlands, among others, are nowadays common deployment settings for Internet-of-Things nodes where communication technologies such as LoRa are becoming popular. In this article, we investigate large-scale fading dynamics of LoRa line-of-sig...

Ria Formosa is a complex depositional system that accumulates poorly to very poorly sorted sediments with a polymodal grain size distribution, whose mean diameter varies in a broad range (coarse silts to coarse sands). Quartz and feldspars are the main minerals of the fine-grained fraction of the sediments. The increase of the finer fraction from t...

Exploratory statistical partitioning methods (K-means Clustering analysis) were applied to ADCP monitoring datasets collected inside the Douro and Minho estuaries. This analysis is aimed to discriminate ADCP acoustic responses according to the variations of the suspended particles within the ensonified medium. Based on the interpretation of the res...

The tidal variability of the Minho and Douro lower estuaries (NW Portugal) water column structure was assessed at the semi-diurnal and fortnightly time scales under two contrasting seasonal river flow scenarios during the summer of 2005 and winter of 2006. Sediment fluxes inferred from calibrated ADCP acoustic backscatter revealed that, during spri...

Resting cysts of planktonic dinoflagellates, once produced, sink to the seabed where they can remain viable for a long time. These cysts have important ecological roles, such as acting as the inoculum for the development of planktonic populations. Moreover, dinoflagellate cyst records from depth sediment cores are broadly used as a proxy to infer p...

In this work, a method of identifying distinct suspended sediment populations in terms of concentration and particle size distribution (PSD) is proposed, based solely on the statistical analysis of ADCP acoustic backscatter. The initial hypothesis is stated as that statistically distinct ADCP acoustic responses correspond to statistically distinct...

Surface sediments were sampled at 18 stations from 7 to 64 m depth off the SE coast of Algarve to characterize the organic matter contents in the inner and middle shelf. For each sediment sample, grain size, mineralogy and total organic carbon analyses were carried out, as well as pigment analyses (19’ but-fucoxanthin, fucoxanthin, 19’ hex-fucoxant...

In this work we explore the possibility of extracting indicative suspended sediment information in terms of estimates of concentration and particle size from ADCP single frequency monitoring datasets. In order to accomplish this task, four datasets of LISST field measurements, collected in similar low concentration, near-shore transitional environm...

O areal da Praia Grande apresenta frequentemente uma areia escura que se associa à elevada concentração em minerais pesados. Neste trabalho pretende-se caracterizar este fenómeno e compreender as razões associadas a esta concentração. Para cumprir este objectivo foi analisado um conjunto de amostras de sedimento recolhidas na Praia Grande e em prai...

Grande beach's sand often presents a dark color due to the abundant presence of heavy minerals. This work aim to understand this phenomenon based on the analysis of heavy mineral distribution along Grande beach and adjacent beaches located in the same sedimentary littoral cell (São Lourenço, Foz do Lizandro, Maçãs, Pequena, Adraga, Abano and Guinch...

At Grande beach it is common observe the presence of blackish sand (heavy mineral placer) that makes a contrast with the predominant white sand that characterize the nearby beaches. This study aims to understand the presence of such blackish sand using the mineralogical composition of the Grand beach and 7 nearby beaches was studied. At Grande beac...

The sand from Grande Beach (Sintra, Portugal) often presents a dark color due to high concentration in heavy minerals. This work pretends to characterize this phenomenon as well as to explain what causes it. To fulfill this objective, it was collected a sample set from Grande Beach and other beaches of the same sedimentary littoral cell (São Louren...

The Hydrographic Institute conducted the Program “Monitoring the Quality of the Marine Environment” during the period 1985-2010. Sediment samples were collected in four different areas, each corresponding to a different estuarine area of relevant economic, social, and ecological importance at Portugal Continental Coastal areas : POLAveiro (mouth of...

Whereas using the species percentages is the standard analytical procedure used to infer species ecological preferences, independently of taphonomical effects, the closure problem associated with closed number systems and subsequent inconsistency of determining percentages may lead to spurious correlations, biased statistical analysis and misleadin...

In this study we describe recent coccolith assemblages from surface sediments of the central Portuguese continental margin. By investigating variation in coccolith concentrations and relative abundances along north-south and onshore-offshore gradients and between submarine canyons and open shelf and slope areas, and by correlation of coccolith dist...

In order to quantify the physical forcing processes associated to sediment transport in the inner shelf, sequential moorings were placed in the three access cable routes connecting the Renewable Energy Experiments Zone (offshore S. Pedro Moel - W Portugal) to the shore. ADCP and LISST data was collected to quantify and establish suspended sediment...

No âmbito de um estudo de monitorização ambiental na Zona Piloto (ZP), foram analisados parâmetros físico-químicos em amostras de água e sedimentos. A ZP, ao largo de S. Pedro de Moel, engloba uma área com cerca de 320 km² (Decreto-Lei n.º 5/2008). Neste trabalho, apresentam-se os resultados de metais obtidos da análise de amostras de água e os res...

Efetua-se a caraterização geoquímica e mineralógica dose sedimentos recolhidos com um core de gravidade em dois locais: crista da ilha Terceira e monte submarino Great Meteor (cruzeiro EMEPC G3/2007). Os dois testemunhos verticais de sedimentos são descritos tendo em atenção a granulometria das partículas, o conteúdo em carbono orgânico e inorgânic...

This paper presents a first attempt to characterize coccolithophore assemblages occurring in the context of an active submarine canyon. Coccolithophores from the upper-middle sections of the Nazaré Canyon (central Portuguese margin) - one of the largest canyons of the European continental margin - were investigated during a late winter period (9–12...

Headland sediment bypassing plays a major role in definition of coastal sedimentary budget and consequently in coastal management. This process is particularity important at headland-bay beaches on rocky coasts. However, headland-bay beach research is usually focused on the beach rotation since these beaches are generally regarded as closed systems...

Headland sediment bypassing plays a major role in definition of coastal sedimentary budget and is particularity important to the coastal management of headland-bay beaches on rocky coasts. This work aims to contribute to the understanding of headland sediment bypassing processes in non-artificial environments, taking as a case study a natural coast...

In the framework of the EUROSTRATAFORM project 108 bottom sediment samples (1st cm) from the Nazaré continental shelf have been analysed for grain-size, mineralogy (X-ray diffraction) organic carbon and carbonate contents. The particulate matter (PM) from intermediate (INL) and bottom nepheloid layers (BNL) was also analysed in 84 stations for grai...

Geographic patterns of Cu, Pb and Zn enrichment on the Lisbon-Setúbal-Sines continental shelf and upper slope (central Portuguese margin) were studied in this paper to gain insight into current pathways of trace metal dispersal. Our study is based on the analysis of elemental concentrations and mineralogy of surface sediment samples collected offsh...

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This study examines the seasonal morphological variations at São Torpes beach during the year of 2011. The entire beach surface was monitored and analysed in detail and, the observed changes were related with the incident wave conditions. In spring, when the incident waves came from SW direction with moderate energy, longshore transport dominates a...

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O Instituto Hidrográfico monitorizou desde 1981 quatro áreas de Portugal continental: ria de Aveiro, estuário do rio Tejo, estuário do rio Sado e Ria Formosa no âmbito do programa interno de “Vigilância da Qualidade do Meio Marinho”. Neste trabalho apresentam-se os resultados da análise textural, carbono orgânico total e metais em amostras de sedim...

The high touristic potential of the north-west region in Morocco plays an important socio-economical role, raising the question of the monitoring of its environmental quality. This study provides a preliminary dataset for dissolved heavy metal concentrations in water and grain-size, mineralogy, carbon (organic and inorganic) and heavy metal content...

Two mooring lines equipped with near-bottom sediment traps were deployed in the axis of the Nazaré submarine canyon at ∼1600 and ∼3300 m depth, respectively. We studied time-series of particle flux, composition (biogenic silica, carbonates, organic matter and lithogenic fractions), granulometry, mineralogy and 210Pb concentration of particulate mat...

In order to characterize the beach active layer textural variability, an innovative application of sand digital image analysis was successfully developed and applied at two Portuguese beaches. This method, based on digital image analysis techniques coupled with an acquisition device specially developed for this type of application, allowed the char...

Presently, conceptual and numerical sediment concentration modelling is largely based on the diffusion approach. However, several works have shown that this approach is, frequently, unsuitable to model the profile distribution of different grain size particles in the same flow. In order to understand the grain size effects on suspended sediment con...

This study addresses to the evaluation of the suspended sediment concentration in a fetch limited beach (Alfeite Beach) using optical backscatter sensors (OBS) appraising, simultaneously, sensor response to the physical characteristics of suspended particles. In order to achieve these objectives two OBS sensors, deployed at the intertidal zone of A...

In order to evaluate the role of submarine canyons as transport routes for the particulate matter, including anthropogenic trace metals, from coastal areas to the deep sea, we analysed contents of Ca, Al, Fe, Mn, Zn, Cr, Pb, Ni and Cu, organic carbon and calcium carbonate in surface sediments and sediment trap particulate material from canyon and o...

The Nazare submarine canyon extends similar to 210 km westward from the coast of Portugal, down to a water depth of > 4300 m. The considerable habitat heterogeneity found throughout the canyon is affected by strong currents and high turbidity, especially in the upper parts of the canyon. The canyon morphology comprises steep slopes, scarps, terrace...

The Nazare submarine canyon extends similar to 210 km westward from the coast of Portugal, down to a water depth of > 4300 m. The considerable habitat heterogeneity found throughout the canyon is affected by strong currents and high turbidity, especially in the upper parts of the canyon. The canyon morphology comprises steep slopes, scarps, terrace...

The Nazaré submarine canyon extends ~ 210 km westward from the coast of Portugal, down to a water depth of > 4300 m. The considerable habitat heterogeneity found throughout the canyon is affected by strong currents and high turbidity, especially in the upper parts of the canyon. The canyon morphology comprises steep slopes, scarps, terraces, and ov...

Submarine canyons are assumed to play an important role in oceanic/neritic circulation, marine productivity and sedimentary processes, acting as preferential conduits between the littoral and deep oceanic domain. Here we present first results of a comparative micropalaeontological study on calcareous nannoplankton and benthic foraminifera from surf...

Submarine canyons are considered to be responsible for the major part of mass transfers between the coastal zone and the deep oceanic domain, affecting the oceanic circulation pattern, as well as the distribution of the bottom sedimentary deposits in the shelf nearby. In the framework of HERMES and DEEPCO scientific projects Oporto and Aveiro shelf...

The Portuguese project "ECOIS -Estuarine COntributions to Inner Shelf dynamics" a three year project (2005 to 2007) aimed to determine the Minho and Douro sediment contributions to the inner shelf of the NW Portuguese coast. In this paper some results are presented concerning the textural composition of bottom sediments, collected in 2005 and 2006,...

In-situ observations of nonlinear internal waves (NIWs) propagating over the northern shelf of Portugal, near the Nazaré submarine canyon (39°47.4′N/009°11.4′W), and evidence of their action on the bottom, are presented and discussed. Synthetic Aperture Radar (SAR) images from this margin suggest the generation of NIWs over the canyon head (39°35′N...

Mineralogy and geochemistry of fine-grained sediment fractions have been used since the 1960-ies to identify sediment source. Along the Tróia-Sines littoral-arc (SW Portugal) 126 beach-dune profiles have been sampled as well as sea-cliffs and watercourses located close to the study area. Mineralogical analysis of the fine sediment fraction was carr...

Foram investigadas áreas de risco de leishmaniose visceral canina no município de Camaçari, Bahia. Um total de 278 cães distribuídos em 141 residências, pertencentes a 20 áreas de risco investigadas, foi examinado sorologicamente (ELISA). A soroprevalência geral foi 21,7% (56/258) depois da exclusão dos 20 cães usados no início do estudo para delim...

Holocene changes are recorded by sedimentology and palynology on a 20 in long core retrieved in the mouth of the Douro estuary (northwestern Portugal). Results show that the early Holocene (10720-6530 calibrated [cal] YBP) was characterized by a warm and humid climate as testified by a well-established Pinus-Quercus-Alnus regional forest. Shelf and...

In order to investigate the sedimentary dynamics of the Madeira's southern shelf several aspects of this North Atlantic island shelf were studied. The principal goals of this work are: identification of the major sediment sources to the shelf; understand the sedimentary patterns and obtain further insight into the governing mechanisms of the shelf....

Geologically, the Sines Cape corresponds to a sub-volcanic structure, placed at the southern end of a sandy coast (the Troia-Sines Arc) and at the beginning of a southern extent rocky coast. Sines Cape is a sediment source to the inner shelf deposits, but also plays an important role in littoral processes. A multidisciplinary survey was conducted,...

The main objective of this paper is the use of heavy minerals assemblages in the study of coastal dynamic processes. The study was carried out in a peculiar sector of the Portuguese coast, where an exotic intrusive sub-volcanic complex makes a distinct contrast in the Southwest Portuguese coastal area (Paleozoic formations). To achieve this objecti...

This paper aims to describe the sediment dynamics of the Douro Mud Patch located in the Portuguese continental shelf (western Iberian coast). Based on observations of wave and current climates and through mathematical modelling, an attempt is made to understand the shelf fine-grained particles dynamics, namely the behavior of those particles accord...

The multidisciplinary study (sedimentology: texture, carbonates, organic matter, elemental composition, mineralogy of sand and clay; micropaleontology: foraminifera, calcareous nannoplankton and pollen -and radiocarbon dating) of three cores recovered from the Douro estuary infill has allowed to reconstruct the paleoenvironmental guidelines of this...

Recently an innovative mineralogical approach based on the study of the fine-grained fraction trapped in littoral sands, followed by statistical analysis of selected mineralogical ratios, was used to distinguish present-day beach and dune environments in the NW Portuguese coast (Espinho - Mondego Cape). In this paper we present results from the min...

Submarine canyons are areas of increased exchanges between the continental shelf and the deep ocean. We present preliminary results from a multidisciplinary research focussing the dynamics of several canyon systems that occur along the Portuguese continental margin. The research is being conducted in the framework of EU project Eurostrataform and a...

A multidisciplinary research aimed to characterise the dominant aspects of the Portuguese canyon systems and their role on the shelf-deep ocean sediment exchanges is being conducted in the framework of EU project Eurostrataform. Three contrasting systems are studied: (1) the Nazaré Canyon is a narrow and deep canyon which extends from the deep ocea...

Thus study is based on 31 box-core samples collected mainly from the mud-patches of the Galician and North-Portuguese shelf. Each of these cores, some decimetres in length, have been described, radiographied and sampled each centimetre for grain-size analysis and measurement of the particulate organic carbon (Corg) content. 210Pb excess profiles ha...

Results of a program of observations carried out on the northern Portuguese shelf and slope, between July 1996 and June 1999 are used to characterise the main physical processes of the winter regime. The data set includes time series of waves and currents at mid-shelf (86 m depth) and of winds, atmospheric pressure and sea level at the coast, as we...

The Northern Iberian margin is a typical example of a continental margin subjected to seasonal highly energetic regime (waves and tides) and receiving inputs of continental sediments via riverine discharges. The principal goal of this study has been to use clay minerals as indicators of sedimentary dynamics in the open shelf system. The distributio...

The Galicia-Minho Shelf features two large mud patches, the Douro and the Galicia Mud patches. These are recent sediment bodies that have accumulated under a combination of conditions including: (1) abundant supplies of sediment; (2) morphological barriers that act as sediment traps; and (3) hydrographic conditions that favour the accumulation of f...

The northern Portuguese coastal zone is drained by large Iberian rivers, along which there is intensive industrial, agricultural and urban activity. Offshore of the two main river basins of the Douro and Minho, two fine-grained sedimentary formations can be characterised. A geochemical study of this sediment cover has been performed focussing in pa...

Abstract A general hydrographic and nephelometric survey of the NW Portuguese continental shelf and upper slope was undertaken, under winter and spring conditions. The nepheloid layer dynamics along the shelf during three cruises were controlled, principally by the following factors: (a) the hydrography of the shelf-slope waters, i.e. the nepheloid...

The northern Portuguese shelf, between 41°N and 42°N, is characterised by the presence of a mid-shelf mud deposit, the Douro Mud Patch (DMP). Observations conducted between July 1996 and June 1999 under the framework of project OMEX II–II, are used to examine the impact of the dynamic processes in the lower water column, particularly on the DMP. Th...

In the framework of the EU project "Ocean Margin Exchanges" (OMEX) II-Phase II, a program of observations of the oceanographic and sedimentary conditions on the northern Portuguese shelf (41zN-42zN) was conducted by Instituto Hidrografico, between 1996 and 1999. The program focussed on the winter regime and included wave and currentmeter measuremen...

A general hydrographic, nephelometric and sedimentological surveying of the NW Portuguese continental shelf and slope was undertaken, under winter and spring con- ditions in order to elaborate a conceptual model of suspended sediments (nepheloid layer) dynamics. Two major situations were found: 1) Spring/Summer - with northerly winds (upwelling) an...

Capitulo V Matéria particulada em suspensão _______________________________________________________________________________________ 159 2.Composição das suspensões A composição da MPS reflecte a sua origem. As partículas minerais como o quartzo, o feldspato e os minerais das argilas provêm da erosão continental, enquanto que os compostos orgânicos,...