University of the Algarve

About: University of the Algarve is a education organization based out in Faro, Portugal. It is known for research contribution in the topics: Population & Tourism. The organization has 3649 authors who have published 10303 publications receiving 233536 citations.

Recent population expansion and connectivity in the hydrothermal shrimp Rimicaris exoculata along the Mid-Atlantic Ridge

Abstract: Aim Deep-sea hydrothermal vents are unstable habitats that are both spatially and temporally fragmented. In vent species, a 'short-term insurance' hypothesis would lead us to expect mostly self-recruitment, limiting the loss of larvae in the deep ocean or water column and increasing genetic differentiation over the time elapsed since colonization. Alternatively, a 'long-term insurance' hypothesis would support the prediction of selection for large-scale dispersal, to ensure long-term persistence in these ephemeral habitats. The main goal of this study was to infer the spatial and temporal distribution of genetic diversity of the shrimp Rimicaris exoculata, which forms high-density local populations on hydrothermal vents along the Mid-Atlantic ridge. Location Deep-sea hydrothermal vents along the Mid-Atlantic Ridge. Methods We used sequences of mitochondrial cytochrome c oxidase subunit I (COI, 710 bp) to assess the spatio-temporal distribution of genetic diversity across five hydrothermal fields from 36° N to 4° S. Results In contrast to previous results from pioneer studies, very high haplotype diversity was observed in vents across the entire region (i.e. 0.69-0.82), indicating current large effective population size and low drift. The star-like shape of the network of haplotypes, the lack of spatial genetic structure and the significance of tests reflecting demographic effects, together with the fitting of a population expansion model, all support a recent population expansion. Main conclusions Our results suggest a very recent common history of R. exoculata populations/demes along the Mid-Atlantic Ridge, derived after a common bottleneck or founder event and followed by a concomitant demographic expansion. This study therefore suggests a large effective population size and/or high dispersal capacity, as well as a possible recent (re)colonization of Mid-Atlantic hydrothermal vents by R. exoculata.

Contrasting styles of the Holocene highstand sedimentation and sediment dispersal systems in the northern shelf of the Gulf of Cadiz

Abstract: An approach to the interpretation of the Holocene highstand depositional systems and the influence of shelf circulation patterns on sediment dispersal in the northern Gulf of Cadiz shelf (SW Iberian Peninsula) is reported. The study area comprises the transition from the southern Portuguese shelf, lacking major fluvial input, to the Guadiana and Guadalquivir shelves, receiving sediments from fluvial sources. An integrated study using high-resolution seismic profiles and meteorological and physical oceanography data was undertaken to reach the proposed goals. A lateral transition of shelf environments is evidenced during the most recent sea-level highstand period. The Portuguese shelf can be considered as a moderate to high-energy environment, where the dominance of storm events led to the construction of a significant infralittoral prograding wedge, as a consequence of normal incidence of storm waves and steep shelf profile. The Guadiana shelf shows a distinct partition of depositional systems, as a result of a moderate fluvial supply and significant reworking wave and current activity over morpho-structural highs. Proximal facies are attributed to poorly developed prodeltas, whereas distal facies are interpreted as muddy belts. The Guadalquivir shelf is a fluvially dominated environment, as the most prominent feature is a thick, widespread prodelta whose formation has been controlled by significant fluvial supply, moderate hydrodynamic regime and smooth shelf topography. The comparison between sediment transport patterns evidenced in geophysical records and shelf circulation patterns enables us to propose a model for the sediment dispersal during the Holocene highstand period. Sediment dispersal is controlled by an intermittent counter current system, which seems to be intimately linked with the wind regime. Eastward dispersal on the middle to outer shelf is led by the general anticyclonic circulation, dominant under the influence of westerly winds. Westward dispersal occurs in the inshore zones, mainly led by the entrance of warm water tongues on the shelf under the action of easterly winds. These two opposing patterns of sediment dispersal are bounded by zones of current shear (Huelva Front and Strafford Shear).

The Mediterranean Overflow in the Gulf of Cadiz: A rugged journey

Abstract: The pathways and transformations of dense water overflows, which depend on small-scale interactions between flow dynamics and erosional-depositional processes, are a central piece in the ocean's large-scale circulation. A novel, high-resolution current and hydrographic data set highlights the intricate pathway travelled by the saline Mediterranean Overflow as it enters the Atlantic. Interaction with the topography constraints its spreading. Over the initial 200 km west of the Gibraltar gateway, distinct channels separate the initial gravity current into several plunging branches depth-sorted by density. Shallow branches follow the upper slope and eventually detach as buoyant plumes. Deeper branches occupy mid slope channels and coalesce upon reaching a diapiric ridge. A still deeper branch, guided by a lower channel wall marked by transverse furrows, experiences small-scale overflows which travel downslope to settle at mid-depths. The Mediterranean salt flux into the Atlantic has implications for the buoyancy balance in the North Atlantic. Observations on how this flux enters at different depth levels are key to accurately measuring and understanding the role of Mediterranean Outflow in future climate scenarios.

Conspicuous Consumption of the Elite Social and Self-Congruity in Tourism Choices

Abstract: This paper relies on social and economic psychology to explore how the travel choices of Portuguese citizens, with different status levels in their daily lives, perceive and adopt different conspicuous travel patterns because of public exposure. To account for the moderated role of public exposure on conspicuous travel patterns, 36 Portuguese citizens were interviewed. Q-methods were applied to explore the varying senses of conspicuous travel choices among citizens with different levels of public exposure, both individually and relative to each other. Complementary qualitative methods were applied, in order to explore how the interviewees construct tourism conspicuous meanings that match their social or self-representations. The results suggest that social contexts moderate the ways in which individuals perceive and experience conspicuous travel. Further, the results show that public groups with higher exposure tend to prefer subtle signals of conspicuousness, in order to differentiate themselves from the...