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- Projections of maximum tidal inundation limits of estuaries and lagoons of the south Algarve, forced by mean sea level rise: RCP8.5 scenarioPublication . Sampath, Dissanayake; Boski, Tomasz; Moura, Delminda; Veiga-Pires, C.In the present study, we adopted the Hybrid Estuarine Sedimentation Model to simulate the estuarine and lagoon evolution in the South Algarve region due to projected mean sea level rise (MSLR) and sediment deficit scenarios during the 21st century. Thus, we forecasted morphological evolution of six large and medium size estuaries (Guadiana Alcantarilha, Arade, Gilão, Quarteira River, Alvor and a coastal lagoon system (Ria Formosa lagoon) due to the imposed scenarios of MSLR. The projected digital elevation models were used to identify the maximum tidal limits of each system by the year 2100. According to the results, in all cases, saltmarsh habitats and sand flats will be affected severely in response to upper-limit of RCP8.5 scenario of MSLR by 2100. The conjugation of the increase of the mud-flat area and the decrease of saltmarshes will result in the reduction of habitats and then of biodiversity. Habitats associated with the Ria Formosa coastal lagoon and the Guadiana estuary are highly vulnerable to the worst case scenario of MSLR (90 cm higher relative to the year 2011). Agricultural and aquaculture areas in all study areas will be affected due to the landward translation limits of the intertidal areas. Accordingly, it would be advisable to adopt measures to minimize the socioeconomic impacts and loss of ecosystem services in the South Algarve due to climate change driven MSLR during the 21st century and beyond while taking adaptation actions to prevent the loss of environmentally sensitive habitats like salt marshes and sand dunes.
- Aplicação multimédia sobre a Ria Formosa e seus fins educacionais (ForDid)Publication . Oliveira, Sónia; Boski, T.; Moura, Delminda; Mendes da Silva de Sousa, Carlos A; Gomes, Ana; Pereira, LauraNa atualidade torna-se inquestionável a necessidade de integrar a aprendizagem com as novas tecnologias de modo a cativar e facilitar a compreensão dos temas abordados através de aplicações didáticas. Durante a última década o Centro de Investigação Marinha e Ambiental (CIMA) assumiu a responsabilidade de criar meios eficazes de comunicação entre o público em geral e a comunidade científica, através de plataformas multimédia interativas. Foram objecto destas aplicações didáticas as várias vertentes do património natural do Algarve. Após o sucesso das primeiras aplicações GuaDid e MonDid visando o Estuário do Rio Guadiana e a Serra de Monchique respectivamente, o desafio de criar e inovar foi acrescido, resultando numa nova aplicação – ForDid, visando a divulgação do importante sistema lagunar Ria Formosa.
- Mudança do nível do mar no golfo de Cádiz durante o Plistocénico tardio e HolocénicoPublication . Boski, T.; Moura, Delminda; Mendes da Silva de Sousa, Carlos A; Gomes, Ana; Pereira, Laura; Oliveira, Sónia; Santana, PauloThe multiproxy information data set obtained from borehole sequences permitted to establish a robust chronology of events, which led to the post glacial infilling of the terminal stretches of regional river palleovaleys. The paleoecological reconstructions combined with 14C age model of Guadiana Estuary sedimentary record revealed the fast sea level rise period since ca 13.5 kyr cal BP, halted during the Younger Dryas and resuming at ca 11500 yr cal BP. The Holocene history of coastal evolution is also well documented in the Estuary of Arade and in Ria Formoza, pointing to the sea level stabilization at ca 7500 cal BP after a last jump of up to 8 meters in 700 years which corresponds to the Meltwater pulse 1c. Since then, the upwards movement of the sea surface continued at much slower pace, ie with the 1.2 mm yr-1 rate. The integration of the data embracing the period from since ca 13.5 ka cal BP, to the actuality enabled us to propose the sea-level rise curve for the SW Iberian Atlantic margin. When confronted with the current altimetric data from TOPEX/POSEIDON, Jason I and Jason II satellites, the millennial time-scale natural trend enables to estimate the anthropogenic forcing of SLR to be in order of 1.2 – 1.8 mm year.
- Sea-level rise and anthropogenic activities recorded in the late Pleistocene/Holocene sedimentary infill of the Guadiana Estuary (SW Iberia)Publication . Delgado, J.; Boski, T.; Nieto, J. M.; Pereira, L.; Moura, Delminda; Gomes, A.I.; Mendes da Silva de Sousa, Carlos A; García-Tenorio, R.This study reviews data on sea-level rise during the last 13000 yr cal. BP (13 kyr) as recorded in the estuarine sediments of the Guadiana River (SE Portugal, SW Spain). We combined new data from a 63 m-long borehole, drilled through the entire postglacial sedimentary sequence, with information on five previously studied cores. By integrating sedimentological, geochemical and palaeontological proxies, we were able to make a palaeoenvironmental reconstruction of the Guadiana terminal palaeovalley during the last 13 kyr and propose a curve of sea-level rise for the SW Iberian Atlantic margin. Our foraminifera-based palaeoecological reconstruction, anchored to a 14C age model, reveals rapid sea-level rise from 13 kyr, interrupted during the Younger Dryas and resuming ca 11.5 kyr. The pace of marine transgression slackened ca. 7.5 kyr and since then has progressed upwards at a rate of 1.2 mm yr 1. HoloceneeAnthropocene sediments from two boreholes were also analysed to assess the timing, levels and sources of trace metals produced by acid mine drainage from the Iberian Pyrite Belt. Study of metal/aluminium ratios through the profiles allowed background metal concentrations to be estimated from lithostratigraphic units older than ca. 5 kyr (i.e. unaffected by anthropogenic activities). Human activities are especially evident from 4.5 kyr (the beginning of the Copper Age), with anthropogenic sources of metal fluxes prevailing over natural sources (especially Pb, Co, Ni, and Mn, and, to a lesser extent, Zn, Cu, and Ni). Mining activities became particularly intensive between the late Bronze Age and the Roman period (3e1.5 kyr), when the highest metal enrichment factors were recorded: EFPb z 2, EFCd > 10, EFCr z 2, EFCu z 3, EFZn ¼ 1.4.This study reveals the utility of postglacial sedimentary records for reconstructing historical changes in regional water-sediment quality and separating natural and anthropogenic sources of geochemical contaminants.
- Downwearing rates on shore platforms of different calcareous lithotypesPublication . Moura, Delminda; Gabriel, Selma; Ramos-Pereira, Ana; Neves, Mário; Trindade, Jorge; Viegas, José; Veiga-Pires, C.; Ferreira, Óscar; Matias, Ana; Jacob, J.; Boski, T.; Santana, PauloVertical lowering (downwearing) of shore platform surfaces is a very important mechanism in their morphological evolution albeit much remains incompletely understood. The efficacy of mechanical and chemical weathering acting on a given substrate, together with erosional processes, influences downwearing rates. In order to determine the relationship between lithotypes and downwearing rates, data collected from a Transverse Micro-erosion Meter were obtained for shore platforms of three different calcareous lithotypes (biocalcarenite, calcarenite and carbonated siltstone) along the central Algarve coast (Southern Portugal). Downwearing rates ranged between 0.096 mm year−1 and 1.676 mm year−1 in biocalcarenite and weakly cemented calcarenite, respectively. In addition, physical properties of the rocks comprising the platforms were measured, including uniaxial compressive strength (as determined by the Point Load Test), porosity, and calcium carbonate content. The results show that downwearing depends primarily on the intrinsic properties of the substrate. Porosity, in particular, acts in two ways: (i) it tends to weaken the substrate; and, (ii) it controls the downward extent of the water percolation and therefore the depth of the weathering mantle subject to erosion by waves and currents.
- Paleoenvironmental evolution of the Guadiana Estuary, Portugal, during the Holocene: a modern foraminifera analog approachPublication . Camacho, Sarita; Boski, T.; Moura, Delminda; Scott, David; Connor, Simon; Pereira, LauraIn this paper, we reconstruct the Holocene paleoenvironmental evolution of the Guadiana Estuary, southwestern Iberian Peninsula. Two previously studied boreholes (CM3 and CM5) were revisited and analyzed in the light of a foraminifera modern analog approach. Cluster analyses define four assemblages with different biocenotic, taphonomic, elevation and distance-to-sea settings, which serve as a baseline for paleoassemblages interpretation. Faunal changes along the sedimentary sequences, together with previous sedimentological and chronological data, redefine the different phases of environmental evolution in the Guadiana Estuary since ca. 13 kyr cal. BP, with special emphasis on the Holocene marine highstand. Estuarine flooding began synchronously in both locations (ca. 9 kyr cal. BP) but manifested differently in each sedimentary sequence. The most seaward borehole records a more evident and longer highstand (ca. 8.8–3.8 kyr cal. BP), characterized by the occurrence of subtidal environments and by the presence of open marine species (Pararotalia cf. spinigera, planktic forms and a significant number of exotic/allochthonous tests), indicating warmer and more marine conditions than today. In the most landward borehole, the highstand is shorter (ca. 8–7.6 kyr cal. BP) and less intense, characterized by the presence of a diverse, mainly autochthonous, open estuary assemblage, dominated by Ammonia aberdoveyensis and Haynesina germanica. At 4.4 kyr cal. BP, during a long deceleration phase of regional sea-level rise, a short but well-defined pulse of marine influence is recorded in CM5, when open estuarine assemblages reappear and replace marsh agglutinated assemblages, suggesting a new submergence phase. This short event is not identified in the previous works carried out in the same area, thus further data are needed to understand whether it is consequent from a global, warming period or whether it resulted only from local and ephemeral forcing effects.
- Diatomáceas como potencial ferramenta para reconstituições paleoecológicasPublication . Gomes, A.I.; Boski, T.; Moura, DelmindaAs diatomáceas são algas unicelulares que abundam tanto em águas doces como salgadas. Este trabalho mostra que as associações de diatomáceas presentes ao longo de um perfil de sapal, junto à foz do rio Guadiana, são sensíveis a vários parâmetros ambientais. Desta forma, confirma‑se o seu potencial como indicador para reconstruções paleoecológicas em estuários, especialmente no que diz respeito a variações do nível médio do mar, como as ocorridas desde a última transgressão posglacial.
- Geochemical characteristics of sediments along the margins of an atlantic-mediterranean estuary (the Guadiana, Southeast Portugal): spatial and seasonal variationsPublication . Camacho, Sarita; Moura, Delminda; Connor, Simon; Boski, T.; Gomes, AnaThe 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 proxies
- The evolution of the European framework for coastal management, linked to the new environmental challenges. The Portuguese casePublication . Oliveira, Sónia; Moura, Delminda; Boski, T.The sharing of space by various human activities leading to social conflicts and threats to ecosystems, alongside increased awareness of the threats to coastal zones has created the need to legislate on coastal planning and integrated management by developing international guidelines. A new management challenge has emerged due to climate change that had not previously been considered in legislation or policies. Therefore, the European tools and frameworks applied in Portugal, their implementation and effectiveness will be analysed. Extensive bibliographic data was analysed including EU directives and policies, and Portuguese governmental documents from national to a municipal level. We found that all the European Union guidelines and frameworks are being implemented in the Portuguese Governmental planning and are very well substantiated, whereas the base of all land management instruments (IGT), have a questionable implementation, mainly due to the number of entities involved and the long implementation process.
- Taxonomy, ecology and biogeographical trends of dominant benthic foraminifera species from an Atlantic-Mediterranean estuary (the Guadiana, southeast Portugal)Publication . Camacho, Sarita; Moura, Delminda; Connor, Simon; Scott, David; Boski, T.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.