Holocenic evolution of Guadiana River estuary (South of Portugal) based on benthic foraminiferal assemblages

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Habitats of the Guadiana River estuary

The Guadiana River estuary is the most important estuarine system in southern Portugal. The estuary’s variety of habitats supports a great diversity of species. Some of these species have only recently been discovered and are found nowhere else on Earth. This chapter details the current state of knowledge of the estuary’s habitats, with a particular focus on the unseen microscopic flora and fauna that support the entire food chain – and many economic activities – in the estuary.Portuguese Foundation for Science and Technology: Projects PTDC/EPHARQ/4168/2014 and UID/ARQ/04211/2013, the PhD fellow SFRH/BD/62405/2009.info:eu-repo/semantics/publishedVersio

Atlas of benthic foraminifera and thecamoebian species from the Guadiana river estuary

Tese de doutoramento, Ciências do Mar ( Processos de Ecossistemas Marinhos), Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2012This thesis explores the potential of benthic foraminifera as environmental indicators in the Guadiana River estuary according to an actual perspective, where we study the species distribution patterns and their responses to seasonal environmental changes and a paleoenvironmental perspective, in which the previous information in combination with the knowledge of diagenetic processes is applied in interpreting analogues environments that formed in the estuary during the Holocene. The variation of environmental parameters in the estuary showed strong dependence on spatial and seasonal gradients, exhibiting prevailing river conditions in winter and marine conditions in summer. The distribution of foraminifera in the Guadiana estuary mirrored the seasonal variation of environmental factors, whose relative importance depended on the proximity the tolerance limits of the species. The elevation proved to be the most important parameter in the distribution of foraminifera by combining the effect of a series of other variables. Based on the dominant species of living foraminifera and seasonal variations in their relations was possible to define a model of ecological zonation for the Guadiana estuary. Four biocenoses were identified and compared with the fraction of dead and fossil foraminifera. The total assemblage that combines the seasonal and taphonomic effects on modern microfaunas proved to represent reliably the estuary indigenous microfauna. Its application in the interpretation of paleoenvironments recorded over two sedimentary sequences (CM3 and CM5) allowed refining the knowledge on how the estuary has evolved over the past 13 000 cal yr BP. The pioneering study of communities of thecamoebian and tintinnids suggests that both groups are an asset in studies of environmental monitoring and paleoenvironmental reconstruction. The present work demonstrated that the three indicators analyzed, when integrated in a multi-proxy perspective, increase the potential interpretive which can be applied in paleoenvironmental reconstructions.FCT - Fundação para a Ciência e Tecnologia: SFRH/BD/28265/200

Evolução paleoambiental holocénica dos estuários dos rios Guadiana e Arade com base nas associações fósseis de foraminíferos bentónicos

Dissertação de mest., Estudos Marinhos e Costeiros, Faculdade de Ciências do Mar e do Ambiente, Univ. do Algarve, 2004A análise das variações no conteúdo em espécies de foraminíferos bentónicos ao longo de um testemunho de sondagem recolhido no Estuário do Rio Guadiana e de três testemunhos no Estuário do Rio Arade permitiram identificar cinco paleoambientes com diferentes GIM (Graus de Influência Marinha) que ocorreram ao longo do Holocénico. O GIM 1 foi atribuído às amostras indefinidas pela ausência de foraminíferos, traduzindo um ambiente terrestre sem qualquer influência marinha ou um ambiente de deposição não ideal à preservação post-mortem das carapaças. O ambiente sujeito a um GIM 2 foi denominado de intermareal superior e é colonizado exclusivamente por formas aglutinadas (Trochammina macrescens, Trochammina inflata, Trochammina spp., Ammobaculites sp., Eggerella sp.) e forros internos, indicando forte confinamento, típico de médio a alto sapal. O ambiente sujeito a um GIM 3 foi denominado de intermareal médio e é colonizado predominantemente por formas aglutinadas e/ou forros internos e carapaças carbonatas em elevado estado de dissolução, caracterizando um ambiente confinado, típico de médio a baixo sapal. O ambiente sujeito a um GIM 4 foi denominado de intermareal inferior é dominado (mais de 65% dos indivíduos) pela associação das espécies estuarinas Ammonia beccarii e Haynesina germanica associada a Elphidium spp. e aos miliolídeos, caracterizando um ambiente moderadamente confinado, abrangendo o baixo sapal e toda a planície lodosa exposta em baixa mar de marés vivas. O ambiente sujeito ao GIM 5 foi denominado de intermareal aberto e é definido pela associação das espécies estuarinas A. beccarii e H. germanica a formas de maior influência marinha, nomeadamente, os géneros Brizalina, Fissurina, Discorbis, Rosalina e Cibicides, verificando-se ainda um aumento no índice de Diversidade e no número de carapaças indeterminadas e pequenas. De acordo com as sequências paleoambientais, em todas as sondagens se reconheceu a existência de uma fase transitiva fluvio-marinha imediatamente antes de um episódio transgressivo. No estuário do Guadiana, entre um episódio pré-holocénico e o auge de transgressão marinha, foi possível identificar uma sequência paleoambiental de pré-invasão marinha, caracterizada por uma substituição de dominância de espécies de sapal por espécies de baixo sapal e de estuário. No estuário do Arade, os primeiros vestígios de influência marinha coincidem com o período de maior oceanidade, sugerindo a concomitância deste fenómeno com o início da formação do estuário. A inexistência de registo de uma fase de pré-invasão marinha na base dos testemunhos sedimentares deste sistema estuarino sugere que a invasão marinha ocorreu de forma mais abrupta e menos premonitória que no caso do estuário do Guadiana. Em todas a sondagens reconhece-se um abrandamento na incursão marinha logo após o auge transgressivo. A ocorrência de um ambiente de sapal em todos os biohorizontes mais recentes das quatro sondagens sugere um recente equilíbrio entre as taxas de acreção e as taxas actuais de subida do Nível Médio do Mar

Ecological zonation of benthic foraminifera in the lower Guadiana Estuary (southeastern Portugal)

The present study analyzes the spatial distribution and seasonal distribution of live benthic foraminiferal communities in the estuary of Guadiana, the fourth largest river on the Iberian Peninsula, and establishes, through statistical analysis, their relationships with a series of environmental parameters. Forty-four superficial sediment samples were collected along distance-to-sea and elevation gradients in the winter and summer of 2010. Fifty-three foraminifera species were identified along the intertidal margins of the estuary. Foraminiferal distribution reflected seasonal variation of environmental factors, whose relative importance varied according to species tolerances. Elevation in relation to mean sea level appeared to be the most important parameter controlling foraminiferal distribution, probably because it combines the effects of a series of other variables (i.e. organic matter, sediment texture, pH and temperature). In the highest marsh areas, where environmental conditions approach survival thresholds, only some agglutinated species are able to survive. In the lower intertidal zone, where subaerial exposure is diminished and environmental conditions are generally less variable, more diverse faunas, mainly composed of calcareous species, prevail. During winter, when fluvial discharge peaks, agglutinated species represent more than 80% of the total individuals. In summer, when marine conditions prevail, calcareous species become more competitive, increase their densities and expand into higher marsh zones and estuarine upper reaches. In the estuary, three different foraminiferal assemblages are distinguished: i) Miliammina fusca assemblage, which dominates in unvegetated areas of the lower marsh and tidal flats of the mid-upper estuary; ii)Jadammina macrescens assemblage, which dominates in the highest marsh areas in the lower estuary; and iii) Ammonia aberdoveyensis assemblage, which dominates the areas of low marsh and tidal flats of the lower estuary. (C) 2014 Elsevier B.V. All rights reserved.Portuguese Foundation for Science and Technology (FCT) [SFRH/BD/28265/2006]info:eu-repo/semantics/publishedVersio

Características geoquímicas das margens dum estuário Atlanto-Mediterrânico (o Guadiana, Sudeste de Portugal): variação espacial e sazonal

The present work describes spatial and seasonal variability in grain-size, pH and elemental characteristics (TOC, TIC, TN and C/N) in superficial sediments, as well as salinity, temperature and oxygen in the water, within the intertidal range of the Guadiana Estuary, SW Iberian Peninsula, during the year 2010. The results indicate that environmental parameters in the estuary are strongly dependent on spatial patterns, which reflect seasonal oscillations in freshwater discharge. The sediment is generally poorly sorted, with a symmetrical to very finely skewed distribution, in accordance with the low-energy conditions typical of the deposition areas. During winter, heavy rains forced the continuous discharge of Europe’s largest reservoir, the Alqueva dam, creating exceptional hydrodynamic conditions and causing coarser sediment deposition in the estuary. High marsh areas are controlled by flood tides, promoting vertical accretion of muddy sediments, especially silts. The lower areas of the saltmarsh and-mud flat areas are controlled by the ebb, with more efficient export of fines toward the platform and retention of sands, sometimes with significant amounts of bioclasts. In winter (average Q = 654 m3 s -1), salinity remained low throughout the estuary with the highest values (< 3) recorded up to 3 km inland from the river mouth, except in the most confined environments subject to greater evaporation. In summer (average Q = 52 m3 s -1), the estuarine waters are better mixed and significant saltwater intrusion extends approximately 8 km inland. The seasonal variation in surface water temperature was very high, with a difference of ca 14 º C in the maximum temperature recorded in winter and summer. A clear relationship between elevation (in relation to mean sea level) and organic matter, pH and particle size was observed. In the higher areas of the marsh, where the hydrodynamics is attenuated, differential deposition of fine sediments promotes organic matter entrapment and low pH. Sedimentary organic matter derives from a mixture of native aquatic and terrestrial sources. The mid-upper estuary areas and higher zones of the saltmarsh in the lower estuary incorporate a greater terrestrial component, whereas the low-middle marsh areas of the lower estuary experience a substantial contribution from indigenous aquatic sources. The present data help to understand the present environmental condition of the Guadiana Estuary and contribute baseline data for future climatic and environmental management studies based on sediment-dependent proxiesO presente estudo descreve a variabilidade espacial e sazonal das propriedades físico-químicas da água (salinidade, temperatura e oxigénio) e dos sedimentos superficiais (granulometria, pH, COT, CIT, NT e C/N) da faixa intermareal do estuário do rio Guadiana, SW da Península Ibérica durante o ano 2010. Os resultados indicam que as condições ambientais do estuário estão fortemente dependentes dos padrões espaciais e das oscilações sazonais na descarga de água doce. Os sedimentos apresentaram-se geralmente mal calibrados e com uma assimetria tendencialmente fina, de acordo com as condições de baixa energia típicas de áreas de deposição. As fortes chuvas sentidas durante o inverno forçaram a descarga contínua do maior reservatório artificial da Europa, o Alqueva, criando condições hidrodinâmicas excecionais, promovendo o aumento de sedimentos grosseiros no estuário. A granulometria dos sedimentos ao longo da zona intertidal tende a aumentar das zonas mais elevadas às zonas mais baixas. As zonas de sapal alto são controladas pela enchente, promovendo a acreção vertical de sedimentos lodosos, sobretudo siltes. As zonas mais baixas do sapal e zonas de planície lodosa são controladas pela vazante, com exportação mais eficiente de finos para a plataforma e retenção de areias, por vezes com conteúdo significativo em bioclastos. No inverno (média Q = 654 m3 s -1), a salinidade manteve-se baixa ao longo de todo o estuário, com os valores mais elevados (< 3) registados até cerca de 3 km para montante a partir da foz do rio, exceto nos ambientes mais confinados, mais expostos à evaporação. No verão (média Q = 52 m3 s -1), as águas estuarinas apresentaram-se melhor misturadas e a intrusão salina estendeu-se até cerca de 8 km para montante. A variação sazonal da temperatura das águas superficiais foi muito elevada, verificando-se uma diferença de ca 14ºC entre as temperaturas máximas registadas no Inverno e no Verão. No estuário, observou-se uma clara relação entre a elevação (relativa ao nível médio do mar) e a quantidade de matéria orgânica, o tamanho do grão e o pH. Nas zonas mais elevadas do sapal, onde o hidrodinamismo é atenuado, a deposição diferencial de sedimentos finos promove o aprisionamento de matéria orgânica e a diminuição do pH. A matéria orgânica sedimentar deriva de uma mistura de matéria orgânica aquática e terrestre de origem autóctone. As zonas do estuário médio-superior e as zonas mais elevadas do sapal do estuário inferior incorporam uma maior componente orgânica de origem terrestre, enquanto que as áreas de baixo-médio sapal do estuário inferior experienciam uma contribuição substancial proveniente de fontes aquáticas de origem alóctone. A presente informação contribui para o melhor entendimento da atual condição ambiental do Estuário do Rio Guadiana e fornece dados de base para futuros estudos de gestão ambiental e evolução climática que assentem em indicadores ambientais sedimentares.info:eu-repo/semantics/publishedVersio

Taxonomy, ecology and biogeographical trends of dominant benthic foraminifera species from an Atlantic-Mediterranean estuary (the Guadiana, southeast Portugal)

This study analyses the taxonomy, ecology and biogeography of the species of benthic foraminifera living on the intertidal margins of the Guadiana Estuary (SE Portugal, SW Spain). Of the 54 taxa identified during sampling campaigns in winter and summer, 49 are systematically listed and illustrated by scanning electron microscope (SEM) photographs. Ammonia spp. were the most ubiquitous calcareous taxa in both seasons. Morphological analysis and SEM images suggested three distinct morphotypes of the genus Ammonia, two of which proved to be Ammonia aberdoveyensis on the basis of partial rRNA analyses. Jadammina macrescens and Miliammina fusca were the most ubiquitous agglutinated taxa in the estuary. Jadammina macrescens dominates the upper-marsh zones almost exclusively, occurring at very high densities. Ammonia spp. are the most abundant in the low-marsh and tidal-flats of the lower reaches of the Guadiana Estuary, but are widespread throughout the estuary, especially during summer when environmental conditions favor their proliferation. Miliammina fusca dominates the sparsely vegetated low-marsh and tidal-flat zones of the upper reaches, where it is associated with calcareous species. Due to its geographical position, the Guadiana system shares characteristics of both Atlantic and Mediterranean estuaries. This is reflected in the foraminiferal assemblages, with a dominance of thermophilous species and an ecological zonation typical of the Mediterranean climatic zone.info:eu-repo/semantics/publishedVersio

Respuesta de hongos antagonistas bajo dos condiciones de temperatura en un pastizal (Cuenca de Río Blanco, Cundinamarca)

Microbiólogo (a) IndustrialPregrad

Palaeosurface reconstruction based on sedimentary record and in sea level evolution in the Guadiana Estuary (Southern Iberia)

The sedimentary infilling of the Guadiana estuary, in the Southern Iberian Peninsula, has been extensively studied using a variety of laboratory methods, namely geochemical and sedimentological analyses, foraminifera assemblages and palynological profiles, supported by 14C dating [1-3](...

Postglacial sea-level rise and sedimentar response in the Guadiana Estuary, Portugal/Spain border

The study of sedimentological features, foraminifera and molluscan fauna in samples recovered from four rotary boreholes permitted, after 14C dating, the first assessment of the post-glacial transgression in Guadiana River Estuary. The Holocene sequence is underlain by coarse sediments from delta fan enclosing continental swamp deposits dated 16980 year BP. The Holocene sedimentary sequence was deposited either directly on this delta fan gravels or on top of fluvial sands deposited probably between 11000 and 10000 yr BP. An accelerated phase of the estuary infilling by clayey sediments containing the saltmarsh foraminifer Trochammina, began ca. 9800 year BP, when sea level was about 39 m below present. Between 7500 and 7000 year BP, the central part of the estuary started to accommodate coarser sediments, partially introduced from the continental shelf. The first phase of Holocene sea-level rise at a rate of 0.85 m/century terminated ca. 6500 year BP. Since then, lagoonal sediments in the vicinity of the estuary have been enclosed behind sand spits and predominantly sandy sedimentation was initiated within the estuary. After a second phase of slower rise at the rate of 0.3 m/century, which lasted until ca. 5000 year BP, the sea approached the present level.INTERREG II programme, DISIPOL Project (Sediment Dynamics and Pollutant Dissipation in Guadiana River Estuary