Browsing by Author "Brito, Ana"
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- An overview of ecological status, vulnerability and future perspectives of European large shallow, semi-enclosed coastal systems, lagoons and transitional watersPublication . Newton, Alice; Icely, John; Cristina, Sónia; Brito, Ana; Cardoso, Ana Cristina; Colijn, Franciscus; Riva, Simona Dalla; Gertz, Flemming; Hansen, Jens Würgler; Holmer, Marianne; Ivanova, Kateryna; Leppäkoski, Erkki; Canu, Donata Melaku; Mocenni, Chiara; Mudge, Stephen; Murray, Nicholas; Pejrup, Morten; Razinkovas, Arturas; Reizopoulou, Sofia; Pérez-Ruzafa, Angel; Schernewski, Gerard; Schubert, Hendrik; Carr, Laishalla; Solidoro, Cosimo; PierluigiViaroli, null; Zaldívar, José-ManuelThe paper gives an overview of some of the large, shallow, semi-enclosed coastal systems (SECS) in Europe, These SECS are important both from the ecological and the economic perspective (socioecological systems) and provide many valuable ecosystem goods and services. Although some of the systems are transitional waters under theWater Framework Directive, this is not the case for all of the systems. The paper adopts a Driver-Pressure-State-Impact-Response approach to analyse the ecological status, vulnerability and future perspectives of these systems in the context of global change.
- Aplicação de realidade aumentada para o ensino de sólidos geométricosPublication . Leitão, R.; Brito, Ana; Rodrigues, J. M. F.Soluções de realidade virtual e aumentada têm vindo a ser utilizadas no segmento de ensino explorando diferentes modalidades de interação de forma a proporcionar ao aluno acesso efetivo de informação em situações de experiências imersivas em tempo real. Na internet podemos encontrar variadíssimas aplicações educacionais, que nos ajudam a todos, desde as crianças em idade escolar até a profissionais de todas as áreas, proporcionando o estudo mais interativo, divertido e mais envolvente. Neste artigo, onde assumimos que o contexto de ensino é propício para a experimentação de novos modelos de ensino/aprendizagem, apresentamos uma aplicação educacional na área da geometria com o objetivo de potencializar a transferência de conhecimento, salientando as características dimensionais dos sólidos.
- Caracterização sedimentar da plataforma interna do sotavento algarvioPublication . Brito, Ana; Dias, Alveirinho; Ferreira, ÓscarA plataforma continental algarvia há muito que é objecto de estudo por parte de investigadores nacionais e estrangeiros, no que se refere a dinâmica sedimentar. O objectivo deste trabalho é caracterizar a cobertura sedimentar da plataforma interna algarvia desde Vila Real de Santo António até Olhos de Água. Para tal foram recolhidas 199 amostras em 92 perfis perpendiculares à costa entre os meses de Outubro e Novembro do ano de 2005. As amostras foram recolhidas com uma draga Petit Ponar entre os 3 e os 16 metros de profundidade. Analisou-se a granulometria das 199 amostras através do método da peneiração para as classes granulométricas cascalhos e as areias e método da pipetagem para as fracções silto-argilosas. A análise mineralógica foi efectuada em 38 amostras, que se consideraram ser representativas da zona amostrada. Na área estudada as amostras eram maioritariamente constituídas por areias quártzicas. Observaram-se 4 zonas com características granulométricas e mineralógicas distintas: - A zona entre o Rio Guadiana e Cacela caracterizada por areias finas e onde se observava grande quantidade de material silto-argiloso resultante da influência do rio, sendo que o cascalho encontrado nesta zona é de origem biogénica; - A zona entre Cacela e Cabo de Santa. Maria (Ria Formosa Este) caracterizada por areias médias de origem quártzicas, influenciada pelas condições hidrodinâmicas de menor energia; - A zona entre Cabo de Santa. Maria e Garrão é constituída por areias finas quartzica influenciada pela maior exposição à onda dominante do que a zona anteriormente aludida; - A zona entre Garrão e Olhos de Água, constituída por areias grosseiras e cascalho de origem quártzica, influenciada pelo contributo das arribas pouco consolidadas existentes na zona.
- Changes in the yield of microphytobenthic chlorophyll from nutrients: Considering denitrificationPublication . Brito, Ana; Newton, Alice; Tett, Paul; Fernandes, TeresaThe yield of microphytobenthic (MPB) chlorophyll from nitrogen expresses the relationship between chlorophyll formation and nutrient consumption within the surface sediment. In shallow coastal lagoons MPB have an important role in chlorophyll dynamics and may represent the majority of microalgal chlorophyll pigments. Given that chlorophyll has been used as an indicator of eutrophication, the yield is of utmost importance. Furthermore, the yield is a key parameter in models that aims at predicting eutrophication. Estimates of the MPB yield have been previously obtained from a series of microcosm experiments. However, discrepant results in nitrogen fluxes suggested the importance of other processes such as denitrification. Therefore, denitrification rates were used for the calculation of nutrient fluxes and new yield estimates were obtained for muddy sediments. Whereas the earlier estimate obtained was of 4.1 g chl. ( mol N)−1, after including the denitrification rate in the calculation this value was reduced from 5 to 35%.
- Development of an optimal methodology for the extraction of microphytobenthic chlorophyllPublication . Brito, Ana; Newton, Alice; Tett, Paul; Fernandes, TeresaBenthic microalgae are important primary producers in intertidal shallow systems. Their biomass can be estimated by the assessment of chlorophyll a concentration. A rapid and reliable method of measuring chlorophyll a is by spectrophotometer. There is however, no standard protocol for the analysis of benthic chlorophyll a. Although the most common solvent generally used is 90% acetone, some authors showed better results with methanol and ethanol. Some pre-treatments, such as the addition of fine inert granules or ultrasound bath, have also been suggested as factors that improve the extraction efficiency. Sediment samples were collected from two sites, muddy and sandy, located within Ria Formosa (Portugal). The aim of this work was to test the effectiveness of different pre-treatments in the extraction and to develop an optimal method for chlorophyll a extraction and analysis. Pre-treating samples did not yield any significant differences in chlorophyll a extracted. Treating sediments with acetone was found to yield higher concentrations of chlorophyll a, both for muddy and sandy sediments. Acetone was therefore found to be the best solvent for both sediment types, with 90% being the best strength for sandy and 80% the best for muddy sediments. These differences may be related to differences in the structure of the algal communities. Six hours of extraction was found to be sufficient, since after a six hour period the extraction efficiency did not improve.
- Does microphytobenthos resuspension influence phytoplankton in shallow systems? A comparison through a Fourier series analysisPublication . Brito, Ana; Fernandes, Teresa; Newton, Alice; Facca, Chiara; Tett, PaulShallow coastal lagoons, especially the ones with clear waters and lighted substrata, are likely to have large microphytobenthos (MPB) communities. MPB is an important component of these systems, representing up to 99% of the chlorophyll concentration when compared to phytoplankton. It is therefore expected that MPB resuspension play a key role in the dynamics of phytoplankton due to the tide and wind action. Water samples were collected twice per month inside and outside Ria Formosa lagoon (Portugal), for nutrients and chlorophyll a (chl a). Sediment samples were also collected for MPB chl a. Chl a was also analysed in water and sediment samples from Venice lagoon (Italy), at least once per month. A truncated Fourier series was fitted to the data to investigate the seasonal and high-frequency components of the time-series. In the Ria Formosa, the best significant fit for MPB was obtained considering the sum of 26 wave-pairs (sin and cosine), which explained 31% of the variability. The seasonal cycle (1e3 waves) explained approximately 5% of the total variability. Within-day variability which includes spatial heterogeneity explained 61% of the variability. The best fit for phytoplankton inside Ria Formosa was obtained considering the sum of 23 wave-pairs. Outside the lagoon the best fit was obtained using only the sum of 16 wave-pairs. For both cases, the sum of waves explained more than 64% of the variability and the seasonal cycle explained more than 31% of the variability. It is expected that primary producers in the water column have a strong seasonal factor due to the direct effect of the solar cycle, which is the case of other clear waters. In the Venice lagoon, which is microtidal, the best fit for MPB was obtained using 10 wave-pairs. However, the best fit for phytoplankton was obtained with only 3 wave-pairs, indicating the importance of the seasonal cycle. Significant relationships were found between phytoplankton inside and outside the Ria Formosa, as well as between microphytobenthos and phytoplankton in the lagoons of Venice and Ria Formosa. These results suggest the influence of MPB resuspension in the phytoplankton community of shallow coastal lagoons and the importance of phytoplankton exportation to the coastal zone.
- How will shallow coastal lagoons respond to climate change? A modelling investigationPublication . Brito, Ana; Newton, Alice; Tett, Paul; Fernandes, TeresaCoastal shallow lagoons are important ecosystems in terms of their high ecological relevance. They act as buffers of the landesea interface, providing valuable ecosystem services such as nutrient recycling, decomposition of organic matter and removal of pollutants. Lagoons are regions of restricted exchange, subject to anthropogenic pressures that result in problems such as eutrophication. Because they are shallow, submerged primary producers play a prominent role in lagoon system metabolism. Furthermore,coastal lagoons are particularly vulnerable to global climate change and may act as ‘sentinel systems’. Sea level rise already threatens to overwhelm some lagoons, such as Venice and Moroccan lagoons. Recent observations and studies have shown that a global climate change, especially the warming of the climate system and the sea level rise is unequivocal (IPCC, 2007). Therefore, the dCSTTMPB model, which deals with nitrogen and chlorophyll concentrations in the water column and within the sediments, was used to explore a range of scenarios that aimed at representing these changes. The tendency of the light limitation due to the sea level rise is the potential degradation of the microphytobenthos community. This reduction would lead to stronger nitrogen fluxes from pore water to the water column, increasing significantly the nitrogen concentrations. No increase in the phytoplankton community was found because it is mainly influenced by the resuspension of microphytobenthos. High nitrogen concentration may be the first indication of an eutrophication event. Nonetheless, nitrogen may be exported to the sea and cause problems in the adjacent coastal waters. The increase in temperature did not lead to significant differences.
- OCPortugal consortium: activities and challengesPublication . Brito, Ana; Brotas, V.; Cristina, Sónia; D'Alimonte, D.; Goela, Priscila; Icely, John; Kajiyama, T.; Moore, Gerald; Newton, Alice; Sá, C.The newly-constituted Ocean Colour Portugal consortium (OCPortugal) aims at promoting the use of remote sensing (RS) products in the Atlantic off Portugal. In close collaboration with the European Space Agency (ESA), OCPortugal currently links the following institutions: Centre of Oceanography (IO), Faculty of Sciences of the University of Lisbon; CENTRIA and CITI from Faculty of Science and Technology , New University of Lisbon (FCTUNL); and Sagremarisco-Viveiros de Marisco Lda. Through a coordinated set of actions undertaken by these research groups, OCPortugal brings together expertise in different research areas such as marine biology, applied optics, satellite imagery, and parallel computing.
- Phytoplankton dynamics in southern Portuguese coastal lagoons during a discontinuous period of 40 yearsPublication . Brito, Ana; Quental, Teresa; Coutinho, Teresa; Branco, Maria; Falcão, Manuela; Newton, Alice; Icely, John; Moita, TeresaShallow coastal lagoons in southern Portugal, such as the Ria Formosa and Alvor, are considered to be highly important both ecologically and economically. Given the impact of phytoplankton in the ecosystem productivity, it is important to understand its dynamics and to consider them for the assessment of ecosystem health. All available phytoplankton data(chlorophyll a; selected species composition and abundance) within the period from 1967 to 2011 were compiled within the framework of a project to implement the Water Framework Directive. Chlorophyll a (chl a)measurements in Ria Formosa from 1967 to 1968, 1985 to 1986, 1991 to 1992, 2006 to 2008, and 2010 show similar monthly averages with some exceptions. In the 80’s the monthly averages were less than half of what was observed in the 60’s. In the 90’s, the chl a concentrations increased significantly and in the period from 2006 to 2010, chl a concentrations ranged between the values found in the 80’s. The decrease in chl a concentrations during the 80’s is likely to be associated with a peak in shellfish production. Shellfish production was recorded to have decreased from 1990 onwards. Chl concentrations in Ria de Alvor are found to vary within the same range as in Ria Formosa. However, data are limited and does not allow a detailed historical comparison. During the most important chl a peaks, the phytoplankton community was characterized by coastal species, such as Pseudo-nitzschia sp., which may be associated with upwelling events. This was found in Ria Formosa both in the 90’s and from 2000 onwards, as well as in the most recent data from Ria de Alvor. This clearly indicates the influence of the coastal dynamics in these lagoons. High chl outside the lagoon confirmed the influence of coastal waters. In addition, high chl concentrations were also observed at inner parts of the lagoon but not outside, suggesting the existence of an interior maximum. The community was mainly characterized by the existence of low salinity tolerant species, such as Kryptoperidinium foliaceum. Over the time intervals in this study, the 90th percentile values of chlorophyll a concentrations were 3.0 in Ria Formosa and 2.6 mg m 3 in the Ria de Alvor. In a five-fold classification of ecological quality from High to Bad, we propose chlorophyll a concentrations of 5.3 mg m 3 as a reference value, 8 mg m 3 for the boundary High/Good, and 12 mg m 3 for the boundary Good/Moderate. According to this, all water bodies were considered as in High status.
- Sediment and water nutrients and microalgae in a coastal shallow lagoon, Ria Formosa (Portugal): Implications for the Water Framework DirectivePublication . Brito, Ana; Newton, Alice; Tett, Paul; Fernandes, TeresaCoastal shallow lagoons are considered to be highly important systems, which have specific biogeochemical cycles and characteristics. The assessment of sediment–water interfaces is essential to understand nutrient dynamics and to evaluate the vulnerability to eutrophication, especially in regions of restricted water exchange (RRE), such as the Ria Formosa, which have natural conditions for the accumulation of nutrients. Water samples were collected during the years of 2006 and 2007–08 for nutrients, chlorophyll a and dissolved oxygen. Sediment samples were also collected for pore water nutrients and microphytobenthic chlorophyll a. Measurements of temperature, salinity and photosynthetic active radiation were also taken. The lagoon salinity is affected by occasional strong rainfall events. From comparison with previous work, a decrease in the nitrogen concentration in the water column can be observed, which may indicate an improvement of the water quality. Pore water nutrient concentrations were significantly larger than in the water column. Sediment–water exchanges are considered to be the most important processes in nutrient dynamics of the lagoon. Benthic microalgal biomass was also large compared with that of the phytoplankton. It represents about 99% of the total microalgal chlorophyll biomass of the system. The lagoon also contains (discontinuous) meadows of intertidal seagrass, but we did not study these. Due to the importance of sediments, the standard monitoring plans required by the Water Framework Directive may fail to track changes in the nutrient conditions and the microalgal responses to them.