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Abstract: The Lagoa da Apúlia is a unique feature in the NW coastal zone of Portugal, a remaining form from a lagoon complex system that, during the Late Holocene, was dominant in the region. This system was mainly neotectonically controlled, occupying a depressed area bounded by faults on a Palaeozoic rocky lower platform, today observable on beaches at low tide. With the intention of knowing the main architecture of the palaeo-lagoon, geophysical prospecting with GPR and resistivity was carried out. Accordingly, six cores were taken and the sedimentary and mineralogical facies, and diatom and foraminifer contents were analysed, and five rich organic layers were dated by radiocarbon analysis. With the data, an evolutionary environment reconstruction model was created for this palaeo-lagoon and the main structural features of the neighbouring area. [Copyright &y& Elsevier]

Abstract: The Douro estuary sand spit (NW Portugal) is an important natural defence against the impact of storm events. Aiming to improve navigation safety, a breakwater was built to stabilise the spit. In 2001, a monitoring programme was set up to understand the dynamics of the sand spit and, later, to evaluate breakwater efficiency on stabilising the spit''s shape and volume. Nine years of periodic, accurate 3D digital elevation models obtained from kinematic differential Global Positioning System surveys were used to assess spatial and temporal changes in the spit morphology before and after the breakwater construction. Temporal and spatial spit dynamics were further related to river discharge flows, wave action and wind energy. Although the breakwater had a stabilising effect on most of the spit''s area and volume, it caused a clear change in the morphology of the spit''s head and in the previously observed patterns of erosion and accretion. Before breakwater construction, erosion was significantly correlated with extreme river discharge and wind conditions; accretion was significantly correlated with extreme wind conditions; and spit area and volume at 1–2 m elevation with extreme wave conditions. After breakwater construction, these correlations were not found, but the eastern (inland) face of the spit and particularly its southern part became more susceptible to the observed extreme river discharge flows, wave and wind conditions. The instability in the SE part of the spit may pose a threat to an existing local Nature Reserve. Furthermore, before breakwater construction, the spit often breached during severe floods favouring river discharges. The strengthening of the spit after breakwater construction may reduce the likelihood of breaching and lead to more severe flood effects in the estuary. [Copyright &y& Elsevier]

Understanding dune ecosystem responses to multi-scale environmental changes can provide the framework for reliable forecasts and cost-efficient protocols for detecting shifts in prevailing coastal dynamics. Based on the hypothesis that stress and disturbance interact as primary community controls in coastal dunes, we studied the fine-scale floristic assembly of foredune vegetation, in its relation to topography, along regional and local environmental gradients in the 200 km long coastline of northern Portugal, encompassing a major biogeographic transition in western Europe. Thirty topographic profiles perpendicular to the shoreline were recorded at ten sites along the regional climate gradient, and vegetation was sampled by recording the frequency of plant species along those profiles. Quantitative topographic attributes of vegetated dune profiles (e.g. length or height) exhibited wide variations relatable to differences in prevailing coastal dynamics. Metrics of taxonomic diversity (e.g. total species richness and its additive beta component) and of the functional composition of vegetation were highly correlated to attributes of dune topography. Under transgressive dynamics, vegetation profiles have fewer species, increased dominance, lower turnover rates, and lower total vegetation cover. These changes may drive a decrease in structural and functional diversity, with important consequences for resistance, resilience and other ecosystem properties. Moreover, differences in both vegetation assembly (in meta-stable dunes) and response to increased disturbance (in eroding dunes) between distinct biogeographic contexts highlight a possible decline in facilitation efficiency under extreme physical stress (i.e. under Mediterranean climate) and support the significance of functional approaches in the study of local ecosystem responses to disturbance along regional gradients. Our results strongly suggest that assessing fine-scale community assembly can provide insights on the relation between dune vegetation, environmental filters and ecosystem processes. A combination of cost-efficient indicators from dune topography and vegetation is thus suggested as a promising approach to survey, forecast and monitor changes in coastal dune ecosystems. [ABSTRACT FROM AUTHOR]