Search

The Douro is one of the longest rivers in the Iberian Peninsula and represents the most important freshwater input into the Atlantic Ocean in the northwestern Portuguese coast. In order to fill the gaps on the comprehension of the spatial variability of the Douro estuarine plume, an innovative methodology was applied to observe and characterize this plume and its spatial and temporal variability. Using images of normalized water-leaving radiance at 555 nm from MODIS (Moderate Resolution Imaging Spectroradiometer) in combination with long-term concurrent wind, tidal and river discharge data (2003-2011), this work evaluates the effect of the main drivers (river discharge, wind and tide) on the plume features. Expected strong relationships between river discharge and turbid levels were detected. A circular pattern is well distinct off Douro estuary when the flow exceeds 500 m3 s-1. Under upwelling favorable winds and high river discharge regime, an offshore expansion is observed. During southerly winds, there is a plume confinement to the coast. Easterlywinds produce a bulge formation with an offshore detachment from the coast while westerly winds tend to confine freshwater close to the shoreline and decrease the cross-shore advection. Under high river discharges, a remarkable tidal influence in the near-field regions is observed close to the coast and near the river mouth.

The influence of freshwater flow on bacterial communities in the estuarine system Ria de Aveiro (Portugal) was investigated at two sites differently impacted by river inputs, representative of the marine and brackish water zones of the estuary. Sampling events were clustered based on hydrological features. The hydrodynamic was simulated with a Lagrangian model and related to microbiological parameters. Estuarine bacteria responded to different freshwater regimes developing distinct patterns of abundance and activity at the marine and brackish water zones. A circulation pattern induced by high river inflow produced vertical stratification in the marine zone, promoting a seaward flux of bacterioplankton, and stimulating the import of riverine phytoplankton and particle-attached bacteria to the brackish water zone. Advective transport and resuspension processes contributed to a 3-times increase in abundance of particle-attached bacteria during intense freshwater inputs. Additionally, bacterial activity in the estuary was controlled by inorganic nitrogen, responding to different freshwater inputs, which, in association with different prevailing sources of organic substrates induced significant changes in bacterial production. The dynamic and main controlling factors of bacterial communities are clearly impacted by freshwater inputs. Therefore, significant changes in the recycling of nutrients by microbial activities can be expected from alterations in freshwater inputs either related to global climate change or regional hydrological regimes.

The buoyancy generated by the Minho estuarine plume can flood the Rias Baixas for long periods, reversing the normal salinity gradients. Thus, the main purpose of this work was to study the propagation of Minho estuarine plume to the Rias Baixas, establishing the wind and river discharge conditions in which this plume affects the circulation and hydrography features of these coastal systems as well as the plume characteristics under the most probable forcing conditions, through the application of the numerical model MOHID. For this purpose, several scenarios with different river discharges and wind were simulated. The numerical results revealed that the Minho estuarine plume responds rapidly to wind variations and is influenced by coastline geometry. Under Minho River discharges higher than 700 m 3 s − 1 and weak northward winds (3 m s − 1 ) the circulation patterns of the Rias de Vigo and Pontevedra are reversed. On the other hand, moderate northward winds (6 m s − 1 ) combined with Minho River discharges higher than 200 m 3 s − 1 , 300 m 3 s − 1 and 700 m 3 s − 1 reverse the circulation pattern of the Rias de Vigo, Pontevedra and Arousa, respectively. Under the same conditions, the water exchange between Rias Baixas was analyzed using a particle-tracking model following the trajectories of particles released close to the Minho River mouth. Over 5 days, under Minho River discharges higher than 2100 m 3 s − 1 combined with northward winds of 6 m s − 1 , an intense water exchange between Rias was observed. However, only 20% of the particles found in Ria de Pontevedra come directly from the Minho River.

The main goal of this study is to use an integrated ecosystem model to study the role of physical, chemical and environmental parameters on the biogeochemistry of the Tagus estuary, the main estuarine system in Portugal. This work was developed as part of EU-funded INSEA project and tried to accomplish two major aims: (1) the development and implementation of a coupled modeling system capable of reproducing all the major characteristics both in physical and biological environments, and (2) to create a coastal management system based on the efficient integration of observations and biophysical models. Our results suggest that both aims were met. In this study we have used a 2D hydrodynamic application coupled to a complex ecological model presented in a companion paper which captures the state of the art of marine ecological models, and also developed during the project. Special emphasis is given to the processes governing temporal and spatial patterns of both phytoplankton and bulk properties, and the physical–biological interactions shaping their variability. The results shown in this paper are indicative of a reasonable performance of the model. It captures the complexity of the Tagus estuary and provides reasonable estimates of the biomass trends of a highly dynamic and interactive community.

A 3D baroclinic model (Mohid) is used to perform hindcast simulations in a tidal channel: the Espinheiro Channel (Portugal). These simulations are conducted for four distinct periods where markedly different river discharge and tides occurred, and the outputs are compared to time series measurements and synoptic thermohaline data. The model reveals its ability in reproducing observed temporal variability in sea level height and along-channel velocity, presenting skill coefficients higher than 0.85. The model qualitatively reproduces along-channel thermohaline distributions at three different vertical levels, during low-to-medium river inflow, underestimating the salinity stratification when the river flow is high (higher than 100 m 3 s - 1 ). In general, the trends inferred from the observations are reproduced by the numerical model. The cross-sectional tidally averaged structure of salinity and longitudinal velocity analyzed near the channel's mouth reveals ebb residual currents at the south shore and flood residual currents at the north shore under low-to-medium river discharge. When the river discharge is high (higher than 100 m 3 s - 1 ), the channel is almost laterally homogeneous in terms of salinity and residual velocity presenting a two-layer structure with flood currents near the bottom and ebb currents at the top layer. The salt transport was also analyzed and follows the same patterns found in the cross-sectional residual velocity. Close to the channel's mouth, the water exchange is mainly driven by the tidal forcing, except under high river flow events when the freshwater extends its influence from the channel's head to its mouth.

Copyright © 2009 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved., Objective: Phrenic nerve motor amplitude (Diaphr Ampl) is predictive of hypoventilation in amyotrophic lateral sclerosis (ALS). We aimed to evaluate its change over disease course and to correlate it to other measurements. Methods: Forty-nine unselected patients (35 men, 13 bulbar-onset, 56.5+/-8.9 years) with definitive or probable ALS were included. They were evaluated at entry (time 0) and 4-6 months (5.2+/-1.0) later (time 1) with: functional ALS rating scale (ALS-FRS) and respiratory subscore (ALS-FRSr); forced vital capacity (FVC); maximal inspiratory pressure (MIP); mean O(2) saturation overnight (SpO(2)mean); sniff maximal inspiratory pressure (SNIP); Diaphr Ampl and mean amplitude of the ulnar nerve response (ADM Ampl). Results: ALS-FRS, ALS-FRSr, Diaphr Ampl, FVC, SNIP, ADM Ampl (p, The first author has a grant from the “Fundação para a Ciência e a Tecnologia”, SFRH/BD/30714/2006. This work was supported by “Fundação para a Ciência e Tecnologia” – PIC/IC/82765/2007.