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Percorrer CIMA por Objetivos de Desenvolvimento Sustentável (ODS) "13:Ação Climática"
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- Early Pleistocene (1.94–1.46 Ma) records for the upper mediterranean outflow Water branch reveal low and high latitude climate influencesPublication . Voelker, Antje; Ducassou, Emanuelle; Balestra, Barbara; Flores, Jose Abel; Acton, Gary D.; Richter, Carl; Xuan, Chuang; Lofi, Johanna; Alberto, Ana; Kuhnert, Henning; Zarikian, Carlos A. AlvarezThe Mediterranean Outflow Water (MOW), modified by paleoceanographic conditions and tectonic processes, played a significant role in the formation of sediments drifts along the Iberian Margin. Using sediment samples from IODP Hole U1387C, we explore the Early Pleistocene history of the upper MOW core above the central Faro Drift in the Gulf of Cadiz. The time series of benthic foraminifer stable isotope and grain size related data have a rigorous stratigraphic framework consisting of nannofossil biostratigraphy and paleomagnetic and delta 18O stratigraphy. The paleoenvironmental records are supplemented by natural gamma ray downhole logging data. Above the hiatus associated with the youngest dolostone, sandy to muddy contourite sedimentation started at 1.946 Ma, i.e., within Marine Isotope Stage (MIS) 74, at IODP Site U1387, slightly younger than at IODP Site U1389. Formation of contourite layers, reflected in the sortable silt and sand percentage records, strongly reacted to precession forcing, including semi- and quarter-precession cycles. The majority of the contourite beds developed during stadial (colder) climate periods, like previous observations from the Early to Late Pleistocene. Formation of contourite layers within MIS 53, MIS 55 and MIS 65, however, appear to be linked to the prevailing atmospheric conditions over North Africa. Periods of poor ventilation in the upper MOW were linked to insolation maxima and reduced ventilation in the Mediterranean Sea. Here, MIS 51 presents a peculiar case as poor ventilation reached from the surface to the lower North Atlantic Deep Water range, reflecting unique interglacial conditions that merit future exploration.
- Seasonal, spatial, and high-frequency monitoring of dissolved oxygen and net ecosystem metabolism in a shallow coastal lagoon, Ria Formosa – PortugalPublication . Correia, Cátia; Jacob, José; Cravo, AlexandraThis study provides a detailed assessment of dissolved oxygen (DO) dynamics and net ecosystem metabolism (NEM) in the Ria Formosa coastal lagoon, highlighting how spatial and temporal variability shape mesotidal ecosystems. Complementary approaches were applied: short-term (24 h) diel oxygen open-water method at two stations (eastern and western boundaries) in comparison with the bottle incubation method, and a 2.5-year high-frequency dataset at an inner station lagoon. DO showed clear seasonal patterns, largely driven by photosynthesis and respiration, but strongly modulated by water circulation and hydrodynamics. Sporadic hypoxic events (DO ≤ 2 mg L−1) were observed but do not represent a risk. The boundary stations are shallower and colonized by submerged vegetation, displayed stronger diel fluctuations than at the inner station, underscoring the role of biological processes in lagoon metabolism. NEM estimates revealed strong spatial contrasts: the western station was autotrophic, while the eastern station predominantly attributed to restricted water exchange. Long-term records from the inner station indicated a slightly heterotrophic status, reinforcing the value of sustained high-frequency monitoring for capturing ecosystem trends overlooked by short-term approaches. The results also highlight lagoon–coastal ocean connectivity, suggesting dual exchanges: local production may be exported offshore to sustain adjacent coastal areas, while coastal processes, such as upwelling, can also influence lagoon metabolism. Methodological comparisons confirmed that bottle incubation method underestimated NEM relative to diel oxygen open-water method, emphasizing the role of hydrodynamics in mesotidal system metabolism. Although sampling focused on western and eastern boundaries and inner lagoon, the strong tidal renewal in the main and secondary channels suggests Ria Formosa overall is close to metabolic balance, with spatial heterogeneity shaped by hydrodynamics, vegetation, and coastal forcing. By integrating short-term, high-frequency, and long-term observations, this study advances understanding of metabolism in coastal lagoons, offering key insights for predicting ecosystem responses to climate change and for guiding management of vulnerable coastal environments.
- Spectral unmixing of coastal dune plant species from very high resolution satellite imageryPublication . Kombiadou, Katerina; Costas, Susana; Gallego-Fernández, Juan Bautista; Yang, Zhicheng; Serrão Bon de Sousa, Maria Luísa; Silvestri, SoniaWhile improvements in the spectral and spatial resolution of satellite imagery have opened up new prospects for large-scale environmental monitoring, this potential has remained largely unrealised in dune ecogeomorphology. This is especially true for Mediterranean coastal dunes, where the highly mixed and sparse vegetation requires high resolution satellites and spectral unmixing techniques. To achieve this aim, we employed random forest regressors to predict the fractional cover of dune plant species in two of the sandy barriers of Ria Formosa (S. Portugal) from WorldView-2 imagery (June 2024). The algorithm, tested with spatially upscaled multispectral drone data and satellite imagery, detected the fractional cover of major species (most abundant classes and bushy vegetation) with reasonable to very good accuracy (coefficient of determination, CoD: 0.4 to 0.8) for the former and reasonable to good accuracy (CoD: 0.4 to 0.6) for the latter. Additional tests showed that (a) including the distance to the shoreline can increase model accuracy (CoD by ~0.1); (b) the grouping of species resulted in an insignificant increase in model skill; and (c) testing over independent dune plots showed generalisation beyond the training set and low risk of overfitting or noise. Overall, the approach showed promising results for large-scale observations in highly mixed coastal dunes.