Mostrando recursos 1 - 20 de 219

  1. MERIS phytoplankton time series products from the SW Iberian Peninsula (Sagres) using seasonal-trend decomposition based on loess

    Cristina, Sónia; Cordeiro, Clara; Lavender, Samantha; Goela, Priscila; Icely, John; Newton, Alice
    The European Space Agency has acquired 10 years of data on the temporal and spatial distribution of phytoplankton biomass from the MEdium Resolution Imaging Spectrometer (MERIS) sensor for ocean color. The phytoplankton biomass was estimated with the MERIS product Algal Pigment Index 1 (API 1). Seasonal-Trend decomposition of time series based on Loess (STL) identified the temporal variability of the dynamical features in the MERIS products for water leaving reflectance ((w)()) and API 1. The advantages of STL is that it can identify seasonal components changing over time, it is responsive to nonlinear trends, and it is robust in the...

  2. Effects of light polarization and waves slope statistics on the reflectance factor of the sea surface

    D'Alimonte, Davide; Kajiyama, Tamito
    Above-water radiometry depends on estimates of the reflectance factor rho of the sea surface to compute the in situ water-leaving radiance. The Monte Carlo code for ocean color simulations MOX is used in this study to analyze the effect of different environmental components on r values. A first aspect is examining the reflectance factor without and by accounting for the sky-radiance polarization. The influence of the sea-surface statistics at discrete grid points is then considered by presenting a new scheme to define the variance of the waves slope. Results at different sun elevations and sensor orientations indicate that the light...

  3. Technical note: Algal Pigment Index 2 in the Atlantic off the southwest Iberian Peninsula: standard and regional algorithms

    Goela, Priscila; Cristina, Sonia; Kajiyama, Tamito; Icely, John; Moore, Gerald; Fragoso, Bruno; Newton, Alice
    In this study, Algal Pigment Index 2 (API2) is investigated in Sagres, an area located in the Atlantic off the southwestern Iberian Peninsula. Standard results provided by the MEdium Resolution Image Spectrometer (MERIS) ocean colour sensor were compared with alternative data products, determined through a regional inversion scheme, using both MERIS and in situ remote sensing reflectances (R-rs) as input data. The reference quantity for performance assessment is in situ total chlorophyll a (TChl a) concentration estimated through a phytoplankton absorption coefficient (i.e. equivalent to API2). Additional comparison of data products has also been addressed for TChl a concentration determined...

  4. International Centre for Coastal Ecohydrology: applying the ecohydrology approach for the sustainable functioning of coastal ecosystems

    Chícharo, L.; Ben-Hamadou, R.; Amaral, A.; Range, P.; Mateus, C.; Piló, D.; Marques, R.; Morais, P.; Chícharo, M. A.
    Coastal areas are among the most sensitive and productive ecosystems around the world, providing for the subsistence of large numbers of people, particularly in developing countries. Human pressure on coastal areas has dramatically increased during the last decades and climate changes will pose new threats to these areas, as expected from sea-level rise and the decrease in freshwater discharges from rivers (Chicharo et al., 2009). The International Centre for Coastal Ecohydrology (ICCE) a newly approved centre under the auspices of UNESCO, in October 2009, is located in the Algarve region (south Portugal). The centre acts as a facilitator and synergetic structure by providing the articulation...

  5. Response of gilthead seabream (Sparus aurata L., 1758) larvae to nursery odor cues as described by a new set of behavioral indexes

    Morais, Pedro; Parra, María P.; Baptista, Vânia; Ribeiro, Laura; Pousão-Ferreira, Pedro; Teodósio, Maria A.
    Temperate marine fish larvae use a series of environmental cues (e.g., olfactory, hearing, visual) to mediate the selection of nursery habitats. However, habitat selection may vary according to individuals' physiological condition. Therefore, this study aimed to determine the ability of gilthead seabream (Sparus aurata L., 1758) larvae to utilize natural odor cues to locate nursery habitats along ontogeny and to examine how it varies with individual's physiological condition. The hypothesis being tested is that S. aurata larvae prefer coastal rocky reefs as nursery areas, but they might use coastal lagoons as nursery grounds—ecosystems known for their productivity—if under starvation conditions,...

  6. Modelling storm-induced beach morphological change in a meso-tidal, reflective beach using XBeach

    Vousdoukas, M. I.; Almeida, L. P.; Ferreira, Óscar
    Extensive XBeach testing took place against field topographic and bathymetric measurements of storm morphological impact at the mesotidal, reflective Faro Beach (S. Portugal). Five monitored events have been selected for XBeach calibration and sets of runs for 768 different set-ups, showed that alongshore profile morphology variations even for the same site, may require different calibration settings, in order to achieve optimal performance. XBeach performed better with higher facua and wetslope values at the reflective parts of the study area and with lower values at the less steep ones. Model sensitivity to calibration settings appeared to increase with beach slope; while the majority of the tested set-ups...

  7. Comparisons of acoustic and optical sensors for suspended sediment concentration measurements under non-homogeneous solutions

    Vousdoukas, M. I.; Aleksiadis, S.; Grenz, C.; Verney, R.
    A set of acoustic and optical turbidity sensors was tested and compared in laboratory conditions under suspended sediment concentrations of the range 0.1-10 g/l. Various well sorted, mixed, as well as natural sediments (including clay, mud and sand) were used to cover a wide range of conditions, with emphasis on bimodal sediments. All optical sensors showed good performance with post-calibration RMS errors typically below 10% of the range and R2 Pearson coefficients exceeding 95% (a=0.1). The Wetlabs produced the smallest RMS errors, followed by the Troll (overall average ~4.3% and 5.8%, respectively), but the differences were not significant. OBS-3+ performance was also good (overall average RMS...

  8. Microplastics effects in Scrobicularia plana

    Ribeiro, Francisca; Garcia, Ana R.; Pereira, Beatriz P.; Fonseca, Maria; Mestre, Nélia C.; Fonseca, Tainá G.; Ilharco, Laura M.; Bebianno, Maria João
    One of the most common plastics in the marine environment is polystyrene (PS) that can be broken down to micro sized particles. Marine organisms are vulnerable to the exposure to microplastics. This study assesses the effects of PS microplastics in tissues of the clam Scrobicularia plana. Clams were exposed to 1mgL-1(20μm) for 14days, followed by 7days of depuration. A qualitative analysis by infrared spectroscopy in diffuse reflectance mode period detected the presence of microplastics in clam tissues upon exposure, which were not eliminated after depuration. The effects of microplastics were assessed by a battery of biomarkers and results revealed that...

  9. Environmental hazard assessment of a marine mine tailings deposit site and potential implications for deep-sea mining

    Mestre, Nélia C.; Rocha, Thiago L.; Canals, Miquel; Cardoso, Cátia; Danovaro, Roberto; Dell’Anno, Antonio; Gambi, Cristina; Regoli, Francesco; Sanchez-Vidal, Anna; Bebianno, Maria João
    Portmán Bay is a heavily contaminated area resulting from decades of metal mine tailings disposal, and is considered a suitable shallow-water analogue to investigate the potential ecotoxicological impact of deep-sea mining. Resuspension plumes were artificially created by removing the top layer of the mine tailings deposit by bottom trawling. Mussels were deployed at three sites: i) off the mine tailings deposit area; ii) on the mine tailings deposit beyond the influence from the resuspension plumes; iii) under the influence of the artificially generated resuspension plumes. Surface sediment samples were collected at the same sites for metal analysis and ecotoxicity assessment....

  10. Identifying toxic impacts of metals potentially released during deep-sea mining: a synthesis of the challenges to quantifying risk

    Hauton, Chris; Brown, Alastair; Thatje, Sven; Mestre, Nélia C.; Bebianno, Maria João; Martins, Inês; Bettencourt, Raul; Canals, Miquel; Sanchez-Vidal, Anna; Shillito, Bruce; Ravaux, Juliette; Zbinden, Magali; Duperron, Sébastien; Mevenkamp, Lisa; Vanreusel, Ann; Gambi, Cristina; Dell'Anno, Antonio; Danovaro, Roberto; Gunn, Vikki; Weaver, Phil
    In January 2017, the International Seabed Authority released a discussion paper on the development of Environmental Regulations for deep-sea mining (DSM) within the Area Beyond National Jurisdiction (the “Area”). With the release of this paper, the prospect for commercial mining in the Area within the next decade has become very real. Moreover, within nations’ Exclusive Economic Zones, the exploitation of deep-sea mineral ore resources could take place on very much shorter time scales and, indeed, may have already started. However, potentially toxic metal mixtures may be released at sea during different stages of the mining process and in different physical phases (dissolved or particulate). As toxicants, metals can...

  11. Alleviation of salt stress using exogenous proline on a citrus cell line

    Lima-Costa, M. E.; Ferreira, S.; Duarte, Amílcar; Ferreira, A. L.
    Salinity constitutes an important abiotic problem since ancient times, world-wide, for it leads to a decrease in productivity of crops with agronomic value. Under salt stress conditions, plant cells develop strategies to cope with Na+ and Cl-, including exclusion and compartmentalisation, induction of antioxidant enzymatic systems and compatible solutes accumulation, such as proline. The precise function of this osmolyte still remains unclear. Proline may act on osmotic adjustment, as a free radical scavenger, protecting enzymes and avoiding DNA damages. It has been also suggested the role of proline in prevention of lipid peroxidation and as a signalling/regulatory molecule. A salt-sensitive...

  12. Diatoms Si uptake capacity drives carbon export in coastal upwelling systems

    Abrantes, Fátima; Cermeno, Pedro; Lopes, Cristina; Romero, Oscar; Matos, Lelia; Van Iperen, Jolanda; Rufino, Marta; Magalhaes, Vitor
    Coastal upwelling systems account for approximately half of global ocean primary production and contribute disproportionately to biologically driven carbon sequestration. Diatoms, silica-precipitating microalgae, constitute the dominant phytoplankton in these productive regions, and their abundance and assemblage composition in the sedimentary record is considered one of the best proxies for primary production. The study of the sedimentary diatom abundance (SDA) and total organic carbon content (TOC) in the five most important coastal upwelling systems of the modern ocean (Iberia-Canary, Benguela, Peru-Humboldt, California, and Somalia-Oman) reveals a global-scale positive relationship between diatom production and organic carbon burial. The analysis of SDA in...

  13. Development of an ecotoxicological protocol for the deep-sea fauna using the hydrothermal vent shrimp Rimicaris exoculata

    Auguste, M.; Mestre, N. C.; Rocha, T. L.; Cardoso, C.; Cueff-Gauchard, V.; Le Bloa, S.; Cambon-Bonavita, M. A.; Shillito, B.; Zbinden, M.; Ravaux, J.; Bebianno, Maria João
    In light of deep-sea mining industry development, particularly interested in massive-sulphide deposits enriched in metals with high commercial value, efforts are increasing to better understand potential environmental impacts to local fauna. The aim of this study was to assess the natural background levels of biomarkers in the hydrothermal vent shrimp Rimicaris exoculata and their responses to copper exposure at in situ pressure (30MPa) as well as the effects of depressurization and pressurization of the high-pressure aquarium IPOCAMP. R. exoculata were collected from the chimney walls of the hydrothermal vent site TAG (Mid Atlantic Ridge) at 3630m depth during the BICOSE...

  14. Coastal storm risk assessment in Europe: examples from 9 study sites

    Ferreira, Óscar; Ciavola, P.; Armaroli, C.; Balouin, Y.; Benavente, J.; Del Río, L.; Deserti, M.; Esteves, L. S.; Furmanczyk, K.; Haerens, P.; Matias, A.; Perini, L.; Taborda, R.; Terefenko, P.; Trifo, E.
    To assess coastal storm risks thi paper compares existing hazards, associated risks, coastal management plans, and civil protection schemes from nine European countries.

  15. Coastal vulnerability assessment based on video wave run-up observations at a mesotidal, steep-sloped beach

    Vousdoukas, Michalis Ioannis; Wziatek, Dagmara; Almeida, Luis Pedro
    Coastal imagery obtained from a coastal video monitoring station installed at Faro Beach, S. Portugal, was combined with topographic data from 40 surveys to generate a total of 456 timestack images. The timestack images were processed in an open-access, freely available graphical user interface (GUI) software, developed to extract and process time series of the cross-shore position of the swash extrema. The generated dataset of 2% wave run-up exceedence values R 2 was used to form empirical formulas, using as input typical hydrodynamic and coastal morphological parameters, generating a best-fit case RMS error of 0.39 m. The R 2 prediction...

  16. Contribution of storms to shoreline changes in mesotidal dissipative beaches: case study in the Gulf of Cadiz (SW Spain)

    Puig, Maria; Del Rio, Laura; Plomaritis, Theocharis A.; Benavente, Javier
    In this study an analysis of storminess and rates of shoreline change is performed and discussed jointly in four geomorphological units of the Gulf of Cadiz (SW Spain) for the period of 1956-2010. For this purpose, storm events are identified based on the following characteristics: wave height above 2.5 m, a minimum duration of 12 h and events with calm periods of less than 24 h were considered as a single event. Subsequently, energy parameters are determined in order to characterize storm-induced impacts. Conversely, geographic information system (GIS) tools are used to measure shoreline changes in aerial photographs and orthophotographs...

  17. Beach erosion and recovery during consecutive storms at a steep-sloping, meso-tidal beach

    Vousdoukas, Michalis I.; Almeida, Luis Pedro M.; Ferreira, Óscar
    This study analyses beach morphological change during six consecutive storms acting on the meso-tidal Faro Beach (south Portugal) between 15 December 2009 and 7 January 2010. Morphological change of the sub-aerial beach profile was monitored through frequent topographic surveys across 11 transects. Measurements of the surf/swash zone dimensions, nearshore bar dynamics, and wave run-up were extracted from time averaged and timestack coastal images, and wave and tidal data were obtained from offshore stations. All the information combined suggests that during consecutive storm events, the antecedent morphological state can initially be the dominant controlling factor of beach response; while the hydrodynamic forcing, and especially the tide and...

  18. RISC-KIT: Resilience-increasing Strategies for Coasts

    Van Dongeren, Ap; Ciavola, Paolo; Martinez, Grit; Viavattene, Christophe; DeKleermaeker, Simone; Ferreira, Óscar; Costa, Cristina; McCall, Robert
    High-impact storm events have demonstrated the vulnerability of coastal zones in Europe and beyond. These impacts are likely to increase due to predicted climate change and ongoing coastal development. In order to reduce impacts, disaster risk reduction (DRR) measures need to be taken, which prevent or mitigate the effects of storm events. To drive the DRR agenda, the UNISDR formulated the Sendai Framework for Action, and the EU has issued the Floods Directive. However, neither is specific about the methods to be used to develop actionable DRR measures in the coastal zone. Therefore, there is a need to develop methods,...

  19. CRAF Phase 1, a framework to identify coastal hotspots to storm impacts

    Ferreira, Óscar; Viavattene, Christophe; Jimenez, Jose; Bole, Annelies; Plomaritis, Theocharis; Costas, Susana; Smets, Steven
    Low-frequency high-impact storms can cause flood and erosion over large coastal areas, which in turn can lead to a significant risk to coastal occupation, producing devastation and immobilising cities and even countries. It is therefore paramount to evaluate risk along the coast at a regional scale through the identification of storm impact hotspots. The Coastal Risk Assessment Framework Phase 1 (CRAF1) is a screening process based on a coastal-index approach that assesses the potential exposure of every kilometre along the coast to previously identified hazards. CRAF1 integrates both hazard (e.g. overwash, erosion) and exposure indicators to create a final Coastal...

  20. Predicting coastal hazards for sandy coasts with a Bayesian Network

    Poelhekke, Laurens; Jager, Wiebke S.; Van Dongeren, Ap; Plomaritis, Theocharis A.; McCall, Robert; Ferreira, Óscar
    Low frequency, high impact storm events can have large impacts on sandy coasts. The physical processes governing these impacts are complex because of the feedback between the hydrodynamics of surges and waves, sediment transport and morphological change. Predicting these coastal changes using a numerical model requires a large amount of computational time, which in the case of an operational prediction for the purpose of Early Warning is not available. For this reason morphodynamic predictions are not commonly included in Early Warning Systems (EWSs). However, omitting these physical processes in an EWS may lead to potential under or over estimation of...

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