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Malignant pheochromocytomas (PHEOs)/paragangliomas (PGLs) are rare tumors for which clinical outcomes remain poorly defined and therapeutic options are limited. Approximately 27% carry pathogenic germline succinate dehydrogenase (SDHx) mutations; the presence of such mutations has been correlated with response to temozolomide (TMZ). We aimed to investigate the association between germline mutations in SDHx and response to TMZ. We retrospectively identified patients with metastatic malignant PHEO/PGLs treated with TMZ- based chemotherapy at Dana-Farber Cancer Institute between 2003 and 2020. The correlation between response by Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 and PET Response Criteria in Solid Tumors (PERCIST) and the presence of SDHx mutations in the germline and tumor was evaluated. Nineteen patients received TMZ. Seventeen underwent germline assessment: 9 (53%) carried a pathogenic SDHx germline mutation. Fifteen patients were evaluable for response by RECIST 1.1: 6 (40%) partial response, 4 (27%) stable disease, and 5 (33%) progressive disease. Overall median progression-free survival was 2.2 years. Three-year overall survival (OS) was 58%. Median PFS was 1.3 years and 5.5 years for carriers and non-carriers, respectively and OS was 1.5 years and not estimable for carriers and non-carriers, respectively. The response by PERCIST criteria in nine patients correlated with the RECIST 1.1 assessment. Our series represents one of the largest analyses of patients with malignant PHEOs/PGLs treated with TMZ who have available germline data. The incidence of pathogenic germline SDHx mutations was similar to what has been previously published, though our analysis suggests that there may be a limited association between response to TMZ and pathogenic germline SDHx mutations.

A high quality data collection has been carried out between 2004 and 2014 to develop the first trophic ECOPATH model for the functioning of the sub and intertidal zones of Ria de Aveiro. This schematic representation allows the characterization of the most important compartments of biomass and flows of energy representing the functioning of the ecosystem, and can be used in the fields of decision-making and management. The model considered 26 functional groups from primary producers to top-predators and two different fisheries (artisanal and leisure), and showed that Ria de Aveiro is a dynamic ecosystem dominated by a high biomass of primary producers, where the transference of energy among compartments is, to a large extent, accomplished through the detritus path. The model also provides several ecological indicators on the state of maturity of the ecosystem, showing that Ria de Aveiro is in an intermediate state of maturity with a relatively complex food web and resilience to environmental changes. As discussed, this state of maturity is probably determined by human action pervading the system to advance in the expectable ecological succession of a coastal lagoon. These aspects, together with indicators of elevated fishing pressure and predation within the system, underline the necessity of controlling illegal extraction activities and monitoring the biomass of the main functional groups of the system, especially top predators, in order to keep the functioning of the ecosystem of Ria de Aveiro in its current condition.

Costa, S.; Picado, A.; Vaz, N.; Coelho, C.; Portela, L., and Dias, J.M., 2018. Climate change effects on suspended sediment dynamics in a coastal lagoon: Ria de Aveiro (Portugal). In: Shim, J.-S.; Chun, I., and Lim, H.S. (eds.), Proceedings from the International Coastal Symposium (ICS) 2018 (Busan, Republic of Korea). Journal of Coastal Research, Special Issue No. 85, pp. 521–525. Coconut Creek (Florida), ISSN 0749-0208. Coastal systems are very important interface areas between land and sea, subject to constant changes motivated by both natural and anthropogenic factors. In addition to the increasing modifications imposed by human activities, natural processes are also being altered as a result of climate change. Important consequences of climate change in coastal systems are sea level rise (SLR) and changes in freshwater discharge, due to modifications in rainfall patterns and air temperature. The aim of this work was to assess the impact of climate changes on the suspended sediment dynamics i...

The Douro River represents the major freshwater input into the coastal ocean of the northwestern Iberian Peninsula. The seasonal and interannual variability of its turbid plume is investigated using ocean color composites from MODIS (Moderate Resolution Imaging Spectroradiometer) sensor aboard the Aqua and Terra satellites (2000–2014) and long-term records of river discharge, wind and precipitation rate. Regional climate indices, namely the Eastern Atlantic (EA) and North Atlantic Oscillation (NAO), were analyzed to identify the influence of atmospheric variability on the generation of anomalous turbid river plume patterns. The connection between the monthly time series of normalized water leaving radiance at 555 nm ( nLw(555) ) and river discharge is high (r = 0.81), which indicates a strong link between river outflow and turbidity levels in the river plume. The equivalent result is found between precipitation and nLw(555) time series, but the peak correlation was found with a 1-month lag, revealing the importance of the river dams on the outflow regulation (r = 0.65). Lag correlations between nLw(555) and EA index show a peak at 1-month lag (r = 0.51). The relation between NAO index and Douro river discharge is considerable (− 0.50), for a time lag of 1-month as well. However, the correlation coefficient between nLw(555) and NAO index presents a maximum peak for a longer period (r = − 0.42 at 3-month). Anomalous turbid plume patterns, not related with estuarine outflow, are found during autumn 2004. A coccolithophore bloom is proposed as a plausible explanation for these unexpected turbid patches.

It is of global interest, for the definition of effective adaptation strategies, to make an assessment of climate change impacts in coastal environments. In this study, the salinity patterns adjustments and the correspondent Venice System zonations adaptations are evaluated through numerical modelling for Ria de Aveiro, a mesotidal shallow water lagoon located in the Portuguese coast, for the end of the 21st century in a climate change context. A reference (equivalent to present conditions) and three future scenarios are defined and simulated, both for wet and dry conditions. The future scenarios are designed with the following changes to the reference: scenario 1) projected mean sea level (MSL) rise; scenario 2) projected river flow discharges; and scenario 3) projections for both MSL and river flow discharges. The projections imposed are: a MSL rise of 0.42 m; a freshwater flow reduction of ∼22% for the wet season and a reduction of ∼87% for the dry season. Modelling results are analyzed for different tidal ranges. Results indicate: a) a salinity upstream intrusion and a generalized salinity increase for sea level rise scenario, with higher significance in middle-to-upper lagoon zones; b) a maximum salinity increase of ∼12 in scenario 3 and wet conditions for Espinheiro channel, the one with higher freshwater contribution; c) an upstream displacement of the saline fronts occurring in wet conditions for all future scenarios, with stronger expression for scenario 3, of ∼2 km in Espinheiro channel; and d) a landward progression of the saltier physical zones established in the Venice System scheme. The adaptation of the ecosystem to the upstream relocation of physical zones may be blocked by human settlements and other artificial barriers surrounding the estuarine environment.

Cohesive sediments play an important ecological role in coastal systems, affecting light penetration in the water column and consequently the local biogeochemical processes. The main aim of this work is to study the water-column light extinction coefficient (k) dependence on cohesive sediment dynamics within Ria de Aveiro lagoon under sea level rise and extreme freshwater discharges events. A coupled estuarine hydrodynamic and transport model is explored, following previous modeling frameworks developed for the Ria de Aveiro. Three scenarios were simulated: a reference scenario (SC1), wherein present hydrodynamic, mean sea level and present freshwater discharges were used to simulate present hydrodynamic and cohesive sediments; a scenario considering local projections of sea level rise of 0.42 m (SC2); and a third one corresponding to maximum freshwater inflow for the lagoon's tributaries (SC3). Results show higher concentrations of cohesive sediments near the rivers mouths, gradually decreasing toward the lagoon's inlet. From SC2 scenario was found that the effect of sea level rise in sediment dynamics and in water-column light extinction coefficient is not significant. However, the tidal prism increase in this case induces a dilution of the sediments concentration from fluvial origin and consequently a slightly k decrease. Contrarily, in SC3 scenario, the extreme freshwater inflow enhances the cohesive sediment concentration in the entire lagoon, limiting the light penetration in the water column. In summary, extreme river discharge events have a highest impact on water-column light penetration in Ria the Aveiro than predicted sea level rise.

Vaz, L.; Serodio, J., Mateus, M., Dias, J.M., and Vaz, N., 2016. Primary production of the benthic microalgae in the bottom sediments of Ria de Aveiro Lagoon. In: Vila-Concejo, A.; Bruce, E.; Kennedy, D.M., and McCarroll, R.J. (eds.), Proceedings of the 14th International Coastal Symposium (Sydney, Australia). Journal of Coastal Research, Special Issue, No. 75, pp. 178–182. Coconut Creek (Florida), ISSN 0749-0208. The Ria de Aveiro is a mesotidal coastal lagoon located in the north coast of Portugal. It has a complex irregular geometry characterized by large intertidal areas and several freshwater tributaries, which are the main sources of nutrients into the lagoon. The dynamics between the tidal propagation and the landward nutrient sources modulates the primary production within the lagoon. Here, primary production may have two main contributors: the chlorophyll in the water column and the benthic microalgae in the bottom sediments. In this work, a new methodology to compute microalgae in the b...

Longo, R.S., Picado, A., Vaz, N. and Dias, J.M., 2016. Biological response of a coastal plain estuary to torrential episodes: a modelling study. In: Vila-Concejo, A.; Bruce, E.; Kennedy, D.M., and McCarroll, R.J. (eds.), Proceedings of the 14th International Coastal Symposium (Sydney, Australia). Journal of Coastal Research, Special Issue, No. 75, pp. 78–82. Coconut Creek (Florida), ISSN 0749-0208. Estuaries are highly dynamic systems with an important impact on biogeochemical cycles and primary production, which may be affected and modified in a climate change context, namely due to extreme rainfall events. This study aims to research chlorophyll-a (Chl-a) and nutrients dynamics in the Tagus estuary under extreme freshwater discharge in a climate change context, using a 2D biophysical model. Three scenarios were set changing the inputs from the main tributaries – Tagus and Sorraia rivers. First, a scenario with one day of extreme discharge for both rivers was considered. Next, and in order to un...

The main purpose of this study is to assess the state of the lower level of the trophic web of a temperate lagoon, the Ria de Aveiro (Portugal), in situations of light or nutrients limitation conditions, that may occur during extreme weather events (eventually associated to climate changes). The increase of the occurrence of extreme events (frequency, intensity and duration) is likely to globally intensify the lagoon turbidity, reducing the depth of light penetration into the water column and shifting the light limitation condition, and therefore reducing phytoplankton biomass and activity. In addition, a scenario of mean river's flow and/or nutrient input decrease may induce a decline of overall phytoplankton biomass and productivity. To research the combined effects of these processes an ecological/eutrophication model was developed and applied for the Ria de Aveiro, dealing with the basic aspects of the lower trophic status of the water column, integrating the nutrient cycling and the main phytoplankton processes. A set of scenarios was designed in order to evaluate the response of the Ria de Aveiro to extreme events, with special emphasis on cases of high precipitation or run-off situations generating high turbidity conditions inside the lagoon, or dry situations or low run-off conditions corresponding to a reduction of the mean precipitation and rivers discharge. Results show that changes in light or nutrients availability may seriously modify the actual lower level state of the lagoon trophic level. Specifically, the occurrence of extreme events in the lagoon ecosystem will shift the lagoon to a light limitation condition, whereas reduction of the rivers discharge will change the nutrients availability, shifting the lagoon to a nutrient limitation condition.

This work studies the influence of the Tagus estuary, Portugal, on the near coastal system using a model application to describe the main physical and biogeochemical processes in the Region of Freshwater Influence (ROFI). It was used as nested modeling approach, downscaling the solution for the general circulation from a larger domain model (the Portuguese coast), to the local Tagus estuary domain. The model is evaluated during a very dynamic and biologic productive period of the year, corresponding to the winter and early summer (January–May 2007). Also during this period, there is a strong freshwater inflow into the Tagus estuary, which in turn modulates the estuarine outflow to the Tagus ROFI. The results focus on water temperature and chlorophyll and a skill assessment was made, given the lack of data required to perform a thorough validation. Simulation results reveal an adequate reproduction of the vertical thermal structure and chlorophyll concentrations. While a fairly reasonable agreement is seen for water temperature, showing no significant thermal stratification at the study area (average surface-to-bottom difference ranging from 1.3 °C to 1.6 °C), chlorophyll vertical profiles show some differences between the model results and the measurements. Maximum model bias for surface temperature is 1.4 °C and ranges from 1 to 2 mg m− 3 for chlorophyll, revealing an underestimation of the predicted chlorophyll and surface temperature for the area in the vicinity of the Tagus mouth. The general trends of surface chlorophyll and surface water temperature are satisfactorily reproduced by the model.

The northwestern coast of the Iberian Peninsula is characterized by a high primary production mainly supported by coastal upwelling, creating an extraordinary commercial interest for fisheries and aquaculture. Considering chlorophyll- a (Chl- a ) as an indicator of primary production, its spatio-temporal variability was researched in this study in the surface water of this upwelling region from 1998 to 2007. Satellite derived Chl- a , Sea Surface Temperature (SST) and Ekman transport data as well as the inflow of the main rivers discharging into the study area were used to investigate the origin of the Chl- a concentration. Empirical Orthogonal Function (EOF) analysis of weekly Chl- a images was performed, as well as correlation analysis between Chl- a concentration, Ekman transport and river discharge. EOF results suggest that the highest Chl- a concentration occurs near the coast up to 60 km offshore. The interannual variability of Chl- a , SST and Ekman transport was also studied considering summer and winter months. Generally, 2005, 2006 and 2007 were the most productive years during the summer months with high Chl- a concentrations along the coast associated to the strong upwelling conditions observed. Otherwise, 1998 seemed to be the most productive year during winter. The absence of upwelling favorable conditions together with localized low SST and considerable discharges, suggests that the high Chl- a concentrations observed during this period are mainly due to the entrance of nutrients through river runoff. However, in winter, high concentrations of colored dissolved organic matter (CDOM), associated with river runoff, are present in the ocean surface, leading to an erroneous strong signal of the satellite. During winter correlations of 0.58 and 0.49 were found between Chl- a concentration and Douro and Minho discharges, respectively, evidencing that high Chl- a concentration was related with river runoff. Otherwise, during summer, Chl- a and Ekman transport exhibited a correlation of − 0.38 indicating that high Chl- a is associated to upwelling events. In summary, it was found that the spatio-temporal variability of Chl- a along the northwestern coast of Iberian Peninsula exhibited the clear influence of upwelling events during summer. Conversely, the variability during winter was mainly due to entrance of nutrients through the rivers discharge which flow into the area.

The Minho River discharge is recognized as particularly important in driving the circulation and hydrography of Rias Baixas, which are highly productive fishery and aquaculture regions extremely sensitive to environmental characteristics. The intrusion of the Minho River plume inside these Rias can reverse the normal circulation pattern and affect the macronutrient concentrations, imposing a control on new production within the estuarine environment. Consequently, detailed knowledge of the propagation of the plume in this zone facilitates largely the management of many exploited and protected local species. Thus, the main purpose of this work is to study the propagation and influence of Minho estuarine plume in Rias Baixas circulation and hydrography through the development and validation of an application of MOHID numerical model including a local coastal nesting configuration fed by Minho River discharge predicted by an estuary model. The nesting configuration and the Minho estuary model were validated and then applied to research the role of the wind and Minho River discharge effects on the circulation reversal. The spring of 1998 was chosen as the validation period for Minho estuarine plume propagation, considering there were field data available for this period confirming the intrusion of the Minho River plume in Rias Baixas and reversing the normal circulation pattern. Predictions replicate accurately the hydrodynamics and thermohaline patterns in Minho estuary and Rias Baixas under these conditions showing that the developed model application reproduces the dynamics of the coupled estuarine-near coastal systems under research. Results showed that a buoyancy intrusion caused by the Minho River reverses the normal estuarine salinity longitudinal gradient and estuarine circulation of the Rias de Vigo and Pontevedra. Moreover, it was found that a continuous moderate Minho River discharge combined with southerly winds is enough to reverse the Rias Baixas circulation pattern, reducing the importance of the occurrence of specific events of high runoff values.

Plecha, S., Picado, A., Chambel-Leitao, P., Dias, J.M., Vaz, N., 2014. Study of suspended sediment dynamics in a temperate coastal lagoon: Ria de Aveiro (Portugal). In: Green, A.N. and Cooper, J.A.G. (eds.), Proceedings 13th International Coastal Symposium (Durban, South Africa), Journal of Coastal Research, Special Issue No. 70, pp. 604–609, ISSN 0749-0208. Suspended sediment concentrations are simulated at Ria de Aveiro, a lagoon located in a temperate climate area in the northwest of Portugal. The fine-grained suspended sediment concentration is analyzed using the numerical model MOHID (www.mohid.com) and spatial maps of instantaneous and maximum concentration and also temporal variability at specified locations are analyzed in order to characterize the influence of the tide and sea level conditions in the suspended sediment concentrations within the lagoon. The highest suspended sediment concentrations were found in upstream areas during ebb conditions due to the river's proximity, while the ...

The Tagus Estuary is the largest estuarine system in the Iberian Peninsula. Located in a heavily populated metropolitan area (Lisbon), the estuary-coastal continuum is subject to significant natural variability (e.g., tidal variations, winds, river inflow, etc.) and human pressures (e.g., sewage outflow, infrastructures, coastal reclamation, dredging, etc.). Since the 1980s, the estuary has been a natural laboratory for a great number of multidisciplinary studies, but also a numerical laboratory to test models and to develop new ideas and numerical methodologies. Hydrodynamic and biogeochemical models have been used ever since to ascertain the main spatial and temporal features of the Tagus system, connecting its dynamic to its biogeochemical cycles, providing numerical tools used to increase knowledge and to manage the estuary and nearby coastal waters. The main objective of this paper is to present a synopsis of the scientific output related to numerical studies in the Tagus system, by reviewing more than fifty papers published over the past four decades. Our work provides a historical background and description of the numerical models implemented to address estuarine hydrodynamics, nutrient uptake, primary production, light availability, seasonal and annual cycles and the link between physical, biological and chemical estuarine oceanography.

Different characteristics of Spartina maritima found in two distinct salt marshes located in different estuaries were analysed through interpretation of their local hydrodynamic patterns, as well as the impact of sea level rise on physical processes and consequently on plant dynamics and salt marshes stability. These salt marshes are situated in two of the most important Portuguese coastal systems, Tagus estuary (Rosário salt marsh) and Ria de Aveiro lagoon (Barra salt marsh), which are dominated by physical processes that induce strong tidal currents. They were monitored during one year and plant and sediment samples of S.maritima were collected quarterly in order to determine the vegetation coverage, above and belowground biomass, organic matter and sediment moisture. Residual circulation, tidal asymmetry and tidal dissipation were determined from numerical modelling results of the MOHID 2D model that was applied to each coastal system, considering the actual sea level and a sea level rise (SLR) scenario.Results suggest that the different characteristics found for Spartina maritima in the Rosário and the Barra salt marshes may be related with the diverse hydrodynamic conditions identified for each salt marsh. Consequently, the exploration of SLR scenario predictions indicates how these salt marshes could evolve in the future, showing that the important changes in these hydrodynamic parameters under climate change context might induce significant modifications in the salt marshes dynamics and stability. SLR scenario could lead to changes in nutrients and sediments patterns around the salt marshes and thus vegetation coverage percentage would be affected. Additionally, as a consequence of flood duration increase, sediment moisture will increase causing a stress condition to plants. Hence, the ratio below/aboveground biomass might increase, becoming critical to plants survival under conditions of accelerated sea level rise. Accordingly, both SLR and expected changes in vegetation coverage percentage in controlling salt marshes evolution have important implications in their stability and consequently in coastal management. These conditions are unlikely to be unique to these salt marshes and it is suggested that similar analyses are replicated for other tidally dominated systems to improve understanding and characterization of their dynamics and stability under climate change context. This work was been supported by FCT in the framework of the research projects PTDC/AAC-CLI/104085/2008 – ECOSAM: Effects of Carbon Dioxide increase on Salt Marshes, LTER/BIA-BEC/0063/2009 – LTER-RAVE: Long term monitoring in the Ria de Aveiro and PTDC/MAR/107939/2008 – DyEPlume: Estuarine Dynamics and Plume Propagation in the Portuguese coast, co-funded by COMPETE/QREN/UE. The second author is supported by the Ciência 2008 Program, financed by the Portuguese Science Foundation. Authors would like to thank to the anonymous reviewers that contributed for this paper improvement, as well as to colleagues whose help was essential for carrying out this work, especially Ana Azevedo, Leandro Vaz, Magda Sousa and Renato Mendes. Thanks for all the support and availability. published

The finding of human remains in aquatic environments is usually attributed to causes such as work-related or recreational accidents, suicides, discarded homicide victims, and natural disasters. When the point and date of entry in the water is unknown, these findings pose serious challenges to forensic analysis given the difficulty to estimate the drift of the body. In this context, the information retrieved from cases where the point of entry and body recovery sites are known, as well as the timing, is significant. Two drowning accidents in marine coastal waters were analyzed. In both cases the post-mortem submersion interval (PMSI) is known, as well as the accident (point of entry) and body recovery sites. Accumulated degree days (ADD) was estimated in both cases using satellite sea surface temperature data. In both cases the bodies were recovered in the vicinity of the accident site (~2 km in case 1 and less than 1 km in case 2). Results were interpreted in terms of oceanographic conditions, physical settings and ADD. The results provide some relevant clues on the fate of human cadavers in coastal marine environments that can be used by officials and agencies involved in the recovery of bodies, as well as by forensic investigators when dealing with these findings.

Picado, A., Alvarez, I., Vaz, N., and Dias, J.M., 2013. Chlorophyll concentration along the northwestern coast of the Iberian Peninsula vs. atmosphere-ocean-land conditions. In: Conley, D.C., Masselink, G., Russell, P.E. and O’Hare, T.J. (eds.), Proceedings 12 th International Coastal Symposium (Plymouth, England), Journal of Coastal Research, Special Issue No. 65, pp. 2047-2052, ISSN 0749-0208. The aim of this work is to investigate the relationship between the atmosphere-ocean-land conditions and chlorophyll a (Chl-a) formation along the northwestern coast of the Iberian Peninsula. Spatial and temporal distribution of Chl-a concentration, sea surface temperature, surface winds and rivers discharge were analyzed from 1998 to 2007, using remote sensing data. Generally, the Chl-a concentrations are higher near the coast showing a seasonal variability. In fact, along the coast there are higher Chl-a concentrations during the dry season (April to September) which can be associated to the upwelling favorable conditions (southward winds). These favorable conditions are related to the presence of cold nutrient-rich water which upwells towards the surface layers enhancing the primary production. During winter months, the wind pattern is usually upwelling unfavorable (northward winds); however high Chl-a concentration also occurs near the coast. These high values could be related to the inland nutrients input through rivers discharge and winter upwelling events. Afterwards, correlation coefficients were computed between Chl-a and upwelling index, SST and rivers discharges. Between June to September chlorophyll and upwelling index are positively correlated, increasing southward (0.58 to the south of the study area). During winter, the correlation coefficient between chlorophyll and rivers discharge is 0.75 in the northern region of the study area. Therefore, during summer months the chlorophyll variations could be explained mainly by the frequent upwelling events, whereas during winter months, high chlorophyll concentration near coast depends on rivers discharges.

The Minho River, situated 30 km south from the Rias Baixas, is the most important freshwater source flowing into the Western Galician coast. This discharge is particularly important in driving the circulation and hydrography of this coastal region. To study this important issue, numerical modeling may constitute an important tool being used to understand the coastal plume effects under different conditions. The main purpose of this study is to implement and validate a marine model able to reproduce the propagation of the Minho estuarine plume. The chosen period for the validation was the spring of 1998, because a high Minho River discharge was reported as well as favorable wind patterns to spread the river plume towards the Rias Baixas. The numerical model MOHID was used through a downscaling approach with a three-level one-way nested scheme. The numerical predictions show good agreement with the observed water level in the entire domain. Also, the measured components of the velocity are well represented by the model, as well as the observed pycnocline, which is predicted for the observed depth. According to the model results, a buoyancy intrusion caused by the Minho river reverses the normal estuarine salinity longitudinal gradient of the Rias de Vigo and Pontevedra. Otherwise, this pattern is not observed in the Ria de Arousa. All these patterns are corroborated by in situ measurements. In summary, the validation results show that the model adequately reproduces the hydrodynamic and thermohaline patterns of the Western Galician coast. published

This work investigates the recent morphological changes at the inlet of a complex coastal system (Ria de Aveiro lagoon, Portugal). This study was carried out using bathymetric data analysis and numerical simulations obtained with the 2DH morphodynamic modelling system MORSYS2D. The present simulations considered only tidal forcing, and a sensitivity analysis was performed by tuning the formula used to compute the sediment transports. A non-uniform sediment grain size distribution for the Ria de Aveiro inlet is considered in the numerical simulations, based on surveys performed in this area. The model results are analysed to assess if they resemble the observed trends of erosion and deposition, as calculated from bathymetric data. A quantitative analysis of the differences between the bathymetric changes obtained through surveys and the numerical results over a period of 3 years considering different sediment transport formulations shows that the formulations of Ackers and White (1973) and Engelund and Hansen (1967) are the ones that best describe the morphodynamic changes driven by tides in the Ria de Aveiro inlet.

The hydrography of the Espinheiro channel, an estuarine tidal channel located within Ria de Aveiro (Portuguese northwest coast), is investigated using the analysis of a thermohaline variables data set as function of two main forcing factors: incoming river flow and tide. Salinity and water temperature vertical profiles were measured twice a month from September 2003 to September 2004 at ten stations along the channel. Furthermore, in order to characterize the upper fluvial region of the channel in terms of these variables, thermohaline properties and current speed were also measured during two tidal cycles at an anchor station near the channel's head. The salinity distribution along the channel is closely related to the incoming river flow and tidal propagation. The water temperature distribution is related to the freshwater temperature seasonal variations and, due to the shallowness of the study area, is also related to the meteorological conditions. Empirical Orthogonal Functions (EOFs) are used to study the salinity and water temperature variations along the channel. The analysis reveal that the first EOF accounts for 87 and 97% of the total variance in vertically average salinity and water temperature, respectively. The temporal variation of the first EOF of the mean salinity and water temperature (PC1) is well correlated to the freshwater inflow (− 0.86) and freshwater temperature (0.79), respectively. Formation of strong salinity gradients has been found in a region between 7 and 8 km from the lagoon's mouth. These strong gradients migrate within a region of about 1 km depending on the tidal regime: neaps or springs and its formation is related to changes in the channel's morphology (depth and width).

1. IntroductionA mathematical model can be considered as anapproximate reconstruction of a real phenomenon.All parameterizations and approximations used inmodels lead to deviations of the model results fromnature. It is an accepted requirement that anumerical model of estuarine hydrodynamicsshould be verified, calibrated and validated beforeused in a practical application. However, theprocedures to perform these tasks are not widelyaccepted (Cheng et al., 1991). Calibration andvalidation methods appear in several forms, de-pending on data availability, water mass character-istics and researchers’ opinion (Hsu et al., 1999).In this work, the Mohid-2D model implementa-tion for the Ria de Aveiro lagoon is presented,describing its assessment through calibration andvalidation against several different data sets. Due tothe lagoon complex geometry and the large numberof calibration stations used, this goal constitutes avery challenging task.The model is calibrated using as a first approach aqualitative comparison of the temporal evolution ofsea surface elevation (SSE) data measured in 1987/1988 at several locations. When a good match isobtained for all stations, the model’s accuracy isevaluated through the determination of the rootmean square (RMS) error and also through thecomparison between amplitude and phase of themain tidal constituents determined from harmonicanalysis of the observed and computed data. Thevalidation procedure is performed using two in-dependent data sets, which includes observations ofcurrent velocities and SSE values (1997 data) andmeasured water fluxes at the lagoon’s inlet for theperiod of October 2002.2. The study areaRia de Aveiro (Fig. 1) is a shallow mesotidallagoon located in the Northwest coast of Portugalð40 38

SUMMARY Electromagnetic fluctuations in the ocean have external sources like ionospheric‐ magnetospheric current systems, and purely internal oceanic sources associated with interaction between water velocity fields and the geomagnetic field, that is, the motionally induced voltage (MIV). During the last decade techniques based on MIV have proven to provide reliable information when applied to the flow monitoring at large oceanic channels. In this paper analysis of data resulting from the implementation of these techniques in a small-scale system, that is, the Ria de Aveiro lagoon (Portugal), is presented. A submarine cable crossing the channel at the entrance of the lagoon (Barra channel) allows the measurement of the potential difference between two electrodes located on both sides of the channel. Spectral analysis of these data reveals that measured voltages are dominated by semidiurnal M2 ,S 2/K2 frequencies. Comparison between the sum of the four main constituents determined by harmonic analysis and the sea surface elevation measured at a tide gauge located at the lagoon mouth reveal that the measured potential difference is proportional to the water flow. To estimate the water flow in this location from the MIV measurements the data collected using this methodology were compared with numerical results obtained from a previously calibrated hydrodynamic model. A value of 720 m 3 s −1 mV −1 was estimated for the coefficient relating voltage and water transport at Barra. Taking this value into account a sediment layer of about 20 m is estimated, at Barra. The results show that it is possible to indirectly measure the water transport (by tidal and residual flows) through the channel by measuring the differences of electrical potential. This demonstrates the applicability of the MIV method to a small-scale system.

In recent years the need to monitor different parameters has led to the development of several architectures able to make real time, un-attended measurements. Particularly in regard to environmental issues, it is very important that the equipment and measuring systems be small and light to avoid maximum interference of the ecosystems studied. In this context, optical fibre sensors have become extremely attractive for use in natural environments to monitor different parameters of biological interest, due to their intrinsic small weight and size and low reactivity to chemical and biological parameters. In this paper we present an innovative and technologically advanced system for the simultaneous measurement of temperature and salinity based on optical fibre Bragg grating sensors and on an optical sensing cable especially designed for large-scale and distributed or quasi-distributed measurements. A prototype of this optical cable was installed in the Mira Channel at Ria de Aveiro, Portugal. Temperature variation during three weeks from 4 to 23 June 2002 is investigated and presented here.

Coastal upwelling is one of the best studied oceanographic phenomena because of its effects on primary production. The western coast of the Iberian Peninsula has high biological diversity, mainly due to this primary production. In this study, the response of salinity and temperature to the occurrence of upwelling was analysed at the Ria de Vigo– and Ria de Aveiro–ocean boundary over the course of a year. Both systems were influenced by similar external forcing, but the response of thermohaline properties differed. Salinity and temperature were dependent on external forcing throughout the water column at Ria de Aveiro, whereas near-bed measurements revealed the presence of upwelled water at Ria de Vigo. Eastern North Atlantic Central Water was observed during spring–summer (summer) at the southern (northern) mouth of Ria de Vigo, but it was not observed at Ria de Aveiro. This difference may be due to the shallowness and narrowness of the Ria de Aveiro mouth, which can limit the entrance of ocean water. The trends found are unlikely to be unique, suggesting that geomorphologic characteristics of system–ocean boundaries determine how physical processes occurring in adjacent coastal areas impact estuarine properties.