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The opening of the Cacela Inlet (southern Portugal) in 2010 led to unforeseen effects observed after 2017, including an extreme acceleration of the retreat of the inland lagoon margin from about 0.2 to 2 m/year. This was a consequence of the development of a large flood delta in an area of limited accommodation space, forcing the main tidal channel to move inland. The coastal retreat currently affects a flat sandy area that separates the old and inactive Cacela cliff from the lagoon. Between 2025 and 2030, the currently inactive Cacela cliff is likely to become active again, posing a potential risk of damage to a medieval fortress and the existing settlement of Cacela Velha, an unforeseen cascading effect of the opening of the inlet. In order to prevent instability and damage to this legally protected area of national and public interest, several coastal management measures will be required. [ABSTRACT FROM AUTHOR]

Aim: Assessment of the fate of microbial contamination driven from treated wastewater disposal at a highly productive zone on a South European coastal lagoon (Ria Formosa). Methods and results: Microbial indicators of contamination (Total coliforms, Escherichia coli, and Enterococci) were evaluated monthly during September 2018–September 2020 at three study areas (Faro, Olhão, and Tavira) under different wastewater discharge flows and hydrodynamic conditions. Additional data on E. coli monitoring in bivalves, available from the national institution responsible for their surveillance was also considered. The maximum microbial contamination was found at Faro, the highest-load and less-flushed study area, contrasting the lowest contamination at Olhão, a lower-load and strongly flushed area. The wastewater impact decreased along the spatial dispersal gradients and during high water, particularly at Faro and Tavira study areas, due to a considerable dilution effect. Microbial contamination at Olhão increased during the summer, while at the other study areas seasonal evidence was not clear. Data also indicate that E. coli in bivalves from bivalve production zones next to the three study areas reflected the differentiated impact of the wastewater treatment plants effluents on the water quality of those areas. Conclusions: Effluent loads together with local hydrodynamics, water temperature, solar radiation, precipitation, and land runoff as well as seabirds populations and environmentally adapted faecal or renaturelized bacterial communities, contributed to microbial contamination of the study areas. [ABSTRACT FROM AUTHOR]

The establishment of large populations of yellow-legged gull Larus michahellis in coastal and urban areas can lead to strong changes in vegetation cover and composition through creating physical disturbance in the vegetation and impacting the soil quality through defecation. In this study, we evaluated the effects of breeding yellow-legged gull populations on tall and short vegetation cover and plant species composition in old (occupied for 13 years) and new (occupied for 3 years) colony sites in grey dunes of the Algarve, southern Portugal. In each site, sampling plots were used to measure the percentage of vegetation cover in areas with and without breeding gulls. In the old colony site, the cover by tall vegetation was substantially reduced and the cover by short vegetation substantially increased in the areas where gulls are breeding in comparison with the adjacent areas. In the new colony sites, there were only minor differences. The increase in cover of short vegetation in the breeding area of the old colony site was mostly by nitrophilous species (Paronychia argentea and Malcolmia littorea) and should be explained by the decrease in vegetation cover of tall plant species and by feces deposition. Tall and slow-growing species Suaeda maritima and Helichrysum italicum covers were negatively affected. Our results showed that yellow-legged gulls affected vegetation cover and composition of grey dunes after 3 years of consecutive breeding, and this should be considered in the management of these habitats where breeding yellow-legged gulls are increasing. [ABSTRACT FROM AUTHOR]

Coastal lagoons are highly productive systems and the quantification of mass fluxes, which is of paramount importance for the sustainable management of these systems, remains poorly studied. In this context, a detailed study was conducted to better understand the exchanges between the productive coastal lagoon Ria Formosa (South-West Europe) and the ocean. The exchanges of water, nutrients, chlorophyll-a and suspended solids between the main inlets (Faro-Olhão inlet - BFO; Armona inlet - BAR; and Ancão inlet - BAN) and adjacent channels (Faro - CF and Olhão - CO) and the adjacent ocean were estimated along complete semidiurnal tidal cycles, under extreme fortnightly tidal ranges and different seasonal and environmental/oceanographic conditions. The net tidal prism was highest during spring tides. Among the three inlets, BFO was the most important in terms of exchange, followed by BAR and BAN. Net transport at BFO was lowest during the Summer campaign, although it exported material that fertilised the adjacent coast. The persistent net export of suspended solids and ammonium suggests the higher biological productivity of Ria Formosa compared to that found in coastal waters. In the Winter campaign, after a period of rainfall and increased land runoff, there was a remarkable export of matter, on which, ammonium and suspended particles exported can exceed 0.3 times and almost 0.9 times, respectively, those imported from coastal water. However, the import of phosphate and nitrate can be attributed to a weak coastal upwelling event, as well to low consumption and nitrification at this period of low temperature. During the Spring and Autumn campaigns, the Ria Formosa was fertilised either by upwelling events or due to rapid consumption of nutrients by phytoplankton in this shallow system. BFO and the other two inlets of the western sector of Ria Formosa are interconnected by CF and CO. The higher nutrient transport was recorded at CF, despite the highest nutrients concentrations was recorded at CO. The data show the strong link between physical and biogeochemical processes with meteorological/oceanographic factors. The study showed that associated biological processes are superimposed on the tidal effect in this system. Data from this study could be used as a reference, particularly important for management of Ria Formosa, a productive system where bivalves production depends deeply on water quality. In addition, the nutrient concentrations and mass exchanges resulting from the different processes can be used as a reference for other lagoon systems where shellfish production is practised. • Exchanges of mass were estimated between Ria Formosa (RF) and the adjacent ocean. • Among the three inlets, BFO arose as the most important regarding mass exchanges. • The net tidal prism was highest during spring tides. • RF fertilised the ocean but being also a sink of dissolved and particulate material. • Meteorological/oceanographic and biological processes superimposed on the tides. [ABSTRACT FROM AUTHOR]

Recruitment is a critical component of the plant life cycle, but little is known about its contribution to community assembly in comparison to later plant stages. We aimed to analyze the relevance of recruitment niche segregation in community assembly using tidal salt marshes in a Mediterranean climate. With this objective, we recorded the spatio-temporal distribution of seedling emergence and its relationships with propagule density and environmental conditions at the community level along the tidal gradient. Results indicate that seedling recruitment was strongly influenced by differential establishment abilities and the effects of sedimentary and meteorological factors that vary seasonally and along the tidal gradient. Taxa colonizing the same habitats showed some similarities in their recruitment patterns, but they also presented enough differences to configure almost a unique recruitment pattern for each taxa. Sediment characteristics segregated recruitment niches at both extremes of the tidal gradient, and the few species colonizing habitats between these two extremes also showed contrasted spatial recruitment patterns. In addition, sequential differences in seedling emergence segregated within high marsh taxa. Most of the taxa exhibited a continuous germination strategy associated to prolonged flowering periods and the ability to germinate along broad salinity ranges. Our results shed light on the importance of recruitment niche segregation to the assembly of plant communities, which is key for understanding their functioning and guiding their management. • Seedling recruitment was strongly influenced by differential establishment abilities. • Seedling recruitment was influenced by sedimentary and meteorological factors. • Sediment characteristics segregated recruitment niches at both tidal extremes. • Sequential differences in seedling emergence segregated within high marsh taxa. • Most of the taxa exhibited a continuous germination strategy. [ABSTRACT FROM AUTHOR]

Despite worldwide proliferation of the genus Caulerpa and subsequent effects on benthic communities, little is known about the nutritional physiology of the Caulerpales. Here, we investigated the uptake rates of ammonium, nitrate, amino acids, and phosphate through the fronds and rhizoids + stolon, the internal translocation of nitrogen, and developed a nitrogen budget for the rapidly spreading Caulerpa prolifera in Ria Formosa lagoon, southern Portugal. Caulerpa prolifera acquired nutrients by both aboveground and belowground parts at similar rates, except nitrate, for which fronds showed 2‐fold higher uptake rates. Ammonium was the preferential nitrogen source (81% of the total nitrogen acquisition), and amino acids, which accounted for a significant fraction of total N acquisition (19%), were taken up at faster rates than nitrate. Basipetal translocation of 15N incorporated as ammonium was nearly 3‐fold higher than acropetal translocation, whereas 15N translocation as nitrate and amino acids was smaller but equal in either direction. The estimated total nitrogen acquisition by C. prolifera was 689 μmol · m−2 · h−1, whereas the total nitrogen requirement for growth was 672 μmol · m−2 · h−1. The uptake of ammonium and amino acids by belowground parts accounted for the larger fraction of the total nitrogen acquisition of C. prolifera and is sufficient to satisfy the species nitrogen requirements for growth. This may be one reason explaining the fast spreading of the seaweed in the bare sediments of Ria Formosa where it does not have any macrophyte competitors and the concentration of nutrients is high. [ABSTRACT FROM AUTHOR]

Jacob, J.; Correia, C.; Torres, A.F.; Xufre, G.; Matos, A.; Ferreira, C.; Reis, M.P.; Caetano, S.; Freitas, C.S.; Barbosa, A.B., and Cravo, A., 2020. Impacts of decommissioning and upgrading urban wastewater treatment plants on the water quality in a shellfish farming coastal lagoon (Ria Formosa, South Portugal). In: Malvárez, G. and Navas, F. (eds.), Global Coastal Issues of 2020. Journal of Coastal Research, Special Issue No. 95, pp. 45–50. Coconut Creek (Florida), ISSN 0749-0208. Ria Formosa is a productive coastal lagoon, located on the south coast of Portugal, and represents the largest national producer of shellfish bivalves (ca. 90% production). This ecosystem is subjected to various anthropogenic pressures, including the discharge of urban wastewater treatment plants (UWWTP), which impacts the lagoon water quality. This study aimed to assess the impact of alterations in the functioning of two UWWTP on the water quality of Ria Formosa, based on chemical variables, phytoplankton composition (including potential harmful species) and faecal contamination. During the period September 2018 - October 2019, water sampling was conducted along dominant longitudinal gradients of the effluent dispersion from the discharge point (1-2 km), for two sites: a decommissioned (OP) and a modified (FO) UWWTP. After modification, the later started receiving a higher influent volume (ca. 40%), under an innovative technology system (biological treatment in aerobic granular sludge). Based on chemical water quality variables, phytoplankton and indicators of faecal contamination, a significant improvement along the longitudinal gradient from the discharge point was observed after OP decommissioning. This improvement was fast, being detected two months after decommissioning, positively affecting areas used as shellfish farming grounds. However, distribution patterns of bacteriological indicators and regular shellfish harvesting interdictions suggested an alternative source of faecal contamination after OP decommissioning. At FO, both chemical variables and bacteriological indicators of faecal contamination revealed a slower improvement, only six-months after the UWWTP alteration. Before that, increased and highly variable ammonium, chlorophyll a concentration, phytoplankton abundances and Escherichia coli densities, revealed an unstable phase. Overall, a lower water quality at FO in respect to OP reflected not only a higher effluent volume but also more restricted water circulation for the former. [ABSTRACT FROM AUTHOR]

Abstract Despite the advances and increase of observations of physical and chemical processes to better understand the functioning of coastal environments, a large gap still exists in quantifying exchanges and interactions between adjacent coastal systems. It is important to bear in mind that the dynamics and mass exchanges depend on the variability of the driving mechanisms and respond to several time scales (tidal, seasonal and inter-annual). The general objective of this work was to unravel the role of the driving forces on the nutrients and chlorophyll- a exchanges at the Ancão inlet of Ria Formosa lagoon during the most productive season - spring. This is the smallest inlet of the western system, the closest to continental interface and the one where migratory patterns are evident. So, the changes along time could be more evident there than at the other two inlets of the western sector. Ancão inlet will serve as a reference to compare the mass budgets exchanged with the ocean with the other two inlets. Specifically, this work intends to: i) better understand the behaviour of this inlet; ii) its role in the mass exchanges; and iii) its interplay with phytoplankton productivity during the peak season. In this context, the transport of water, nutrients and chlorophyll- a (proxy of phytoplankton density) were estimated across the Ancão inlet section during the spring season. Surveys were conducted under extreme fortnightly tidal conditions during 2007, 2009 and 2012, covering different hydrodynamic, meteorological and environmental conditions. To estimate the mass transport, field velocities, nutrients and chlorophyll- a concentrations were measured concurrently along its cross section. Results show that although the hydrodynamic and morphologic changes recorded at this inlet provoked a loss of hydraulic efficiency apparently these did not markedly affect the mass exchanges during the spring productive season. Globally, the contribution and intensity of the meteorological/physical, chemical and biological drivers superimposed those affected by tides, reflected in the differences between the five surveys conducted. Upwelling was frequent during the spring season and played a key role on the exchanges and mass transport through the Ancão inlet. Data also show that nutrients behaved dissimilarly; silicate was consistently exported, nitrate mostly imported, dependent on the intensity of upwelling and biological consumption, while phosphate generally followed the direction of residual circulation. Chlorophyll- a showed a general import except in both 2012 campaigns, when it was exported in small amounts (<1 kg). Data support that during spring season, particularly in periods when upwelling is relevant, the availability of nutrients on the coast will promote afterwards the growth of phytoplankton that enters and fertilizes the Ria Formosa, increasing its productivity. The estimated amounts are relative to the smallest inlet of the western sector of Ria Formosa. In consequence, it may be anticipated that through the other main inlets from this sector the exchanges are intensified and may enhance their contribution to the Ria Formosa fertilization. Highlights • Role of driving forces in mass transport in the Ancão inlet, Ria Formosa is presented. • Morphologic changes at Ancão inlet did not affect markedly the mass exchanges. • Physical/meteorological and biological drivers superimposed those of tidal conditions. • During spring, under upwelling events, the coast further fertilizes the Ria Formosa. • Changes at Ancão inlet might affect the interconnectivity with the other main inlets. [ABSTRACT FROM AUTHOR]

Holocene evolution of the Ria Formosa barrier island system was studied through the examination of a large subsurface dataset acquired from 191 boreholes and five seismic refraction profiles. Two boreholes with total depths of 26 and 16.5 m were selected for a multi-proxy detailed laboratory analysis, including mean grain size distribution, organic matter (OM) content, color variation, shell identification, and benthic foraminifera assemblages. Selected cores are thought to be representative of the identified depositional sub-basins. Subsurface age data from 16 AMS 14C dated samples were plotted against depth and resulted in a coherent age model of sedimentary infill. The system evolution was largely controlled by sediment availability, accommodation space, and Holocene sea level rise, first at a rapid rate of 7 mm/yr from 10 kcal yr BP to 7.25 kcal yr BP, followed by a slowdown to 1.1 mm/yr until present. A conceptual model for the origin and Holocene evolution of the Ria Formosa barrier island system implies three main steps, leading to the present system geomorphology: (1) marine flooding of incised palaeovalleys by the rapid transgression of palaeovalleys in the early Holocene; (2) development of a proto-barrier island chain perched on Pleistocene detritic headlands and steeper interfluve areas during the early to middle Holocene; and (3) full development of the barrier islands chain and enclosing of the coastal lagoon, followed by the maturation of the system with subsequent siltation and salt marsh expansion from the middle Holocene until present. The onset of barrier system formation dates back to ca. 8 kcal yr BP, predating previously proposed age. [ABSTRACT FROM AUTHOR]

This paper illustrates both the potential and challenges of interdisciplinary collaboration amongst researchers from the social sciences/humanities and the natural sciences/engineering in formulating disaster risk reduction measures for coastal regions. The authors aim to share their experiences of working across different scientific and engineering disciplines in the EU project RISC-KIT to co-produce disaster risk reduction measures suitable for specific regional and local contexts, in this case two coastal study areas in Europe (Porto Garibaldi, Italy and Rio Formosa, Portugal). An overview of the historic-cultural origins of scientific disciplines is first presented, explaining the historical fragmentation of scientific knowledge into natural and social sciences and its associated challenges for prior disaster risk studies – and how the current state of an interdisciplinary approach has emerged. This is followed by an analysis of interdisciplinary collaboration, drawing on the experience and data collected (both quantitative and qualitative) from the two case study areas. The article concludes with suggestions to further overcome the segregation of disciplines within disaster risk studies and projects. The authors found that qualitative data help to understand knowledge, values and behaviours of institutional and non-institutional stakeholders in formulating appropriate risk reduction measures to increase resilience in a local context – and that such data work “hand in hand” with quantitative information. Furthermore, the collection of qualitative data by researchers of the natural science and engineering disciplines has the potential to build bridges between disciplines and to stimulate further investigations, as in this case, to explain contradictions in human behaviour when managing risk. [ABSTRACT FROM AUTHOR]

Subterranean estuary seepage faces are recognized as important reactive interfaces that regulate solute transport to coastal ecosystems via Submarine Groundwater Discharge (SGD). Here we describe benthic processes and rates driving the biogeochemical regulation of SGD-borne inorganic N loading into the Ria Formosa lagoon (Iberian peninsula) through a sandy seepage face. Maximum potential NO 3 − reduction rates, obtained by kinetic modeling of advection-controlled flow-through reactor experiments, ranged from 2.33 ± 1.06 to 14.17 ± 0.22 nmol cm −3 “bulk” sediment (bs) h −1 . Maximum potential nitrification ranged from 0 to 7.5 ± 1.3 nmol cm −3 bs h −1 while potential ammonium assimilation was valued at 2.0 ± 0.3 nmol cm −3 bs h −1 . These NO 3 − reduction rates are in good agreement with previous estimates obtained by diagenetic modeling of in-situ porewater NO 3 − vertical profiles at the same location. Potential NO 3 − reduction rates were very sensitive to temperature (Q 10 = 3.5 ± 0.2). Porewater velocity seems to control net NO 3 − reduction rates, probably by determining solute distribution but also its supply to the microbial community by shaping the diffusive boundary layer around sediment particles. Nevertheless, NO 3 − reduction rates seem ultimately limited by organic matter availability at high velocities. Half-saturation constants of NO 3 − for NO 3 − reduction were low, suggesting that the NO 3 − reducing microbial community had high affinity for NO 3 − . In addition, our experiments provide evidence for the occurrence of alternative NO 3 − reduction pathways, including Dissimilatory Nitrate Reduction to Ammonium (DNRA) and apparent aerobic NO 3 − reduction within the shallow subsurface sediment layer (2–12 cm depth). [ABSTRACT FROM AUTHOR]

Interspecific patterns of local population abundances and differences in habitat preference of two seagrass resident pipefish species of the genus Syngnathus were investigated in a semi-protected lagoon system in Southern Portugal. The results of the combination of field surveys across different seagrass meadows and laboratory habitat choice experiments between May and September 2014 demonstrate that the pipefish population structure in a single-species meadow composed of Zostera noltei differed significantly from the ones in a single-species meadow of Cymodocea nodosa and a mixed meadow of both seagrasses. In addition, the two most abundant pipefish species, Syngnathus typhle and Syngnathus abaster , showed interspecific and intersexual differences in habitat selection both on a macro- and a microhabitat scale in laboratory experiments. The study suggests that in addition to the investigated structural characteristics of sea grasses ( i.e. shoot length and density), other factors such as flow velocity may influence habitat selection of syngnathids. [ABSTRACT FROM AUTHOR]

A Geographic Information Systems-based tool is used for macro-landform classification following the Hammond procedure, based upon a Digital Terrain Model (DTM) created from ordinary Kriging. Gentle slopes, surface curvature, highlands and lowlands areas are derived from the DTM. Combining this information allows the classification of terrain units (landforms). The procedure is applied to the Ria Formosa basin (Southern Portugal), with five different terrain types classified (plains, tablelands, plains with hills, open hills and hills). [ABSTRACT FROM PUBLISHER]

Understanding the influence of the main drivers controlling the circulation and the transport in coastal lagoons is a necessary step towards the description of the dynamics of their ecosystems. Thus, the influence of the main physical drivers on the water exchanges in a multi-inlet barrier island (western sector of the Ria Formosa coastal lagoon, Portugal) was investigated. Several scenarios of tide, wind, bathymetry and point source discharges were simulated using a three-dimensional circulation model and a particle-tracking model. The circulation is adequately reproduced by the hydrodynamic model, with root mean square errors of about 5-8 cm for the water levels and 5-10 cm/s for the cross-sectional averaged velocities in the western inlets and main channels. Wind has a negligible effect on the modelled water levels and cross-sectional velocities, with differences smaller than 1 % between the simulations with and without wind. However, results show that wind influences significantly the transport by affecting the residual circulation, with distinct effects depending on the wind direction. Upwelling favourable winds (with west component) increase the landward transport through the Faro-Olhão inlet and promote a larger dispersion of the water-borne material inside the lagoon. The residual circulation between the three inlets of the western sector of the lagoon is also significantly affected by the bathymetry. Results show a decrease of about 50 % of the tidal prism of the Ancão inlet between 2002 and 2011, which reduces its capacity to export waterborne material to the adjacent coastal area and increases the residence times in some areas of the lagoon, with potentially adverse effects on the ecosystems' health. The dispersion of potential contaminants from point sources inside the lagoon to the coastal area depends on the combined effect of the tidal phase and amplitude and the location of the source. Mean residence times for the discharges from the wastewater treatment plants of the western sector ranged from 7 to 18 days. These findings improve the understanding of the influence of the physical forcings in the circulation and transport dynamics of multi-inlet coastal systems. [ABSTRACT FROM AUTHOR]

Nearshore bathymetry is likely to be the coastal variable that most limits the investigation of coastal processes and the accuracy of numerical models in coastal areas, as acquiring medium spatial resolution data in the nearshore is highly demanding and costly. As such, the ability to derive bathymetry using remote sensing techniques is a topic of increasing interest in coastal monitoring and research. This contribution focuses on the application of the linear transform algorithm to obtain satellite-derived bathymetry (SDB) maps of the nearshore, at medium resolution (30 m), from freely available and easily accessible Landsat 8 imagery. The algorithm was tuned with available bathymetric Light Detection and Ranging (LiDAR) data for a 60-km-long nearshore stretch of a highly complex coastal system that includes barrier islands, exposed sandy beaches, and tidal inlets (Ria Formosa, Portugal). A comparison of the retrieved depths is presented, enabling the configuration of nearshore profiles and extracted isobaths to be explored and compared with traditional topographic/bathymetric techniques (e.g., high- and medium-resolution LiDAR data and survey-grade echo-sounding combined with high-precision positioning systems). The results demonstrate that the linear algorithm is efficient for retrieving bathymetry from multi-spectral satellite data for shallow water depths (0 to 12 m), showing a mean bias of − 0.2 m, a median difference of − 0.1 m, and a root mean square error of 0.89 m. Accuracy is shown to be depth dependent, an inherent limitation of passive optical detection systems. Accuracy further decreases in areas where turbidity is likely to be higher, such as locations adjacent to tidal inlets. The SDB maps provide reliable estimations of the shoreline position and of nearshore isobaths for different cases along the complex coastline analysed. The use of freely available satellite imagery proved to be a quick and reliable method for acquiring updated medium-resolution, high-frequency (days and weeks), low-cost bathymetric information for large areas and depths of up to 12 m in clear waters without wave breaking, allowing almost constant monitoring of the submerged beach and the shoreface. [ABSTRACT FROM AUTHOR]

Benthic foraminifera showed a vertical zonation in tidally influenced salt marshes, which has been used for sea level reconstructions. Growing evidence suggested that freshwater influx, salinity, or the pH of interstitial waters has also an impact on the foraminiferal distribution. A tidal flat and salt marsh transect was investigated in the north-western Ria Formosa coastal lagoon, Algarve, Portugal, to constrain the relationship of benthic foraminifera, halophytes, and pore water properties. The dominance of saltworts from the subfamily Salicornioideae and landward increasing soil salinities depicted evaporation as governing environmental factor. The carbonate chemistry from lagoonal and pore waters identified anoxic tidal flat sediments of as main source of total alkalinity. The alkalinity was lower in the salt marsh, where the p CO 2 was extremely high. Salt marsh pore waters showed a high variability of carbonate system parameters, which mirrored small-scale spatial heterogeneities in the soil. The distribution of textulariid salt marsh foraminifera was confined to the vegetated zones, where their abundance increased with elevation. Calcareous species were frequent on the tidal flat and in the highest salt marsh. Many of them were specialised to high salinities or to extreme and variable environmental conditions. Two levels of faunal change in the salt marsh coincide with vegetation zonal boundaries, mean tide or mean high water levels. The two other faunal changes were related to changes in calcite saturation state or organic carbon concentrations. The proportion of textulariids showed a negative correlation with submergence time or elevation, and a significant correlation with pore water p CO 2. The faunal distribution, pore water calcite saturation, and Ammonia dissolution patterns indicated that calcareous species specialised to tolerate carbonate-corrosive conditions prevailed even at lowest saturation levels. [Display omitted] • Foraminifera and halophytes showed a relationship with pore water properties. • Soil salinity and evaporation are the governing environmental factors. • Agglutinated foraminifera were rather related to pore water p CO 2 than to submergence time or elevation. • Calcareous foraminifera specialised to tolerate carbonate-corrosive conditions prevailed at lowest saturation levels. [ABSTRACT FROM AUTHOR]

The Ria Formosa is a shallow and multi-inlet coastal lagoon system in southern Portugal, with six permanent connections to the Atlantic Ocean. The western sector of Ria Formosa comprises three of the main inlets, Ancão, Faro-Olhão and Armona, which contribute ~90% of the total tidal prism of the lagoon. Of those three inlets, Ancão and Faro-Olhão supply the minimum and maximum contribution for these exchanges, respectively. Four field surveys were conducted at these two inlets during the upwelling season (from spring to autumn) to determine the influence of upwelling process upon the hydrographic characteristics in spring tidal conditions: i) spring 2009 (Ancão inlet), ii) autumn 2011 (both inlets) and iii) spring 2012 (Faro-Olhão inlet). Water samples were collected hourly (at three levels), along complete semi-diurnal tidal cycles, to determine chlorophyll a (chl a) and nutrient concentrations. At the same time, the water velocity was measured along the cross section to estimate the tidal prism, nutrients and chl a transports. Ancão inlet contributes a much lower volume to the total tidal prisms than Faro-Olhão inlet. The temporal data variability reveals that chl a and nutrient dynamics through these inlets depends not only on the tidal influence and characteristics of the boundary waters, but also on the intensity of the atmospheric and oceanic forcings acting on the adjacent coastal zone. During pulses of coastal upwelling events, more evident in spring season (mainly in April 2009 and May 2012), the two inlets imported chl a and phosphate. In contrast, in the absence of upwelling conditions, due to wind reversals and/or long periods of wind relaxation, both inlets exported nitrate and phosphate, fertilizing the coastal ocean. However, the Ria Formosa is a highly complex hydrodynamic system, and hydrographic temporal differences can be expected at different scales as a result of changes in: i) morphological configuration of the natural inlets, ii) interconnectivity of channels, and iii) the seasonal meteorological and oceanographic conditions. [ABSTRACT FROM AUTHOR]

The Ria Formosa is a tidal multi-inlet shallow-water coastal lagoon located in the south of Portugal, subjected to the dry Mediterranean climate. The tide controls the Ria's exchange with the adjacent shelf for most of the hydrological year except for isolated torrential run-off events. Episodes of low hypoxia reported in the literature may be related to the lagoon's flushing time, affecting its shellfish production valued at 20 - 50 million €y-1. Over the past decades several observational and modelling studies presented values for the capacity of the tide to renovate the water inside the Ria. However, these studies lack either the spatial resolution to yield results unaffected by numerical diffusion or analyze a very limited part of the lagoon's territory. In this work, we use a very-high resolution hydrodynamic model to assess the flushing time exclusively due to tidal forcing inside the Ria Formosa. A bi-dimensional implementation of the finitevolume/ finite-difference Eulerian-Lagrangian hydrodynamic and transport model (ELCIRC) was used, allowing for the local refinement of the computational domain, which best suits the lagoon's complex morphology. The present model configuration was validated for tidal propagation with sea surface elevation collected in 1979/80 at 11 lagoon stations. The validation results show a good agreement between predicted and observed elevations, with root mean square errors lower than 20 cm and skill values higher than 0.98. A set of experiments were carried out by releasing a conservative tracer at different stages of the tide at discrete points of the Ria, where possible environmental hazard hot-spots are located and the flushing e-folding time calculated from the tracer's dilution. The results are discussed taking into account the propagation of the tide in this multi-inlet, meandering topography. Evidence is presented of topographic trapping due to the complex spatial distribution of the phase lags of the semi-diurnal tidal constituents. This evidence explains the significant increase of the flushing time from the inlets to the head of the channels, thus justifying the use of detailed spatial resolution when modelling such a complex system. [ABSTRACT FROM AUTHOR]

Lencart e Silva, J. D., Lopes, C. L., Picado, A., Sousa, M. C., Dias, J. M., 2014. Tidal dispersion and flushing time in a multiple inlet lagoon. 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. 598-603, ISSN 0749-0208. The Ria Formosa is a tidal multi-inlet shallow-water coastal lagoon located in the south of Portugal, subjected to the dry Mediterranean climate. The tide controls the Ria's exchange with the adjacent shelf for most of the hydrological year except for isolated torrential run-off events. Episodes of low hypoxia reported in the literature may be related to the lagoon's flushing time, affecting its shellfish production valued at 20 - 50 million €y−1. Over the past decades several observational and modelling studies presented values for the capacity of the tide to renovate the water inside the Ria. However, these studies lack either the spatial resolution to yield results unaffected by numerical diffusion or analyze a very limited part of the lagoon's territory. In this work, we use a very-high resolution hydrodynamic model to assess the flushing time exclusively due to tidal forcing inside the Ria Formosa. A bi-dimensional implementation of the finite-volume/finite-difference Eulerian Lagrangian hydrodynamic and transport model (ELCIRC) was used, allowing for the local refinement of the computational domain, which best suits the lagoon's complex morphology. The present model configuration was validated for tidal propagation with sea surface elevation collected in 1979/80 at 11 lagoon stations. The validation results show a good agreement between predicted and observed elevations, with root mean square errors lower than 20 cm and skill values higher than 0.98. A set of experiments were carried out by releasing a conservative tracer at different stages of the tide at discrete points of the Ria, where possible environmental hazard hot-spots are located and the flushing e-folding time calculated from the tracer's dilution. The results are discussed taking into account the propagation of the tide in this multi-inlet, meandering topography. Evidence is presented of topographic trapping due to the complex spatial distribution of the phase lags of the semi-diurnal tidal constituents. This evidence explains the significant increase of the flushing time from the inlets to the head of the channels, thus justifying the use of detailed spatial resolution when modelling such a complex system. [ABSTRACT FROM AUTHOR]

The present work aims to characterize Ria Formosa water quality considering its spatial, and temporal variability at two scales: short-term (among seasons) and long-term to evaluate its evolution over the past 40 years, by comparing six historical datasets with data obtained in this study. To attain these goals, four field surveys under different seasons and/or weather conditions were conducted between 2017 and 2019 at seven sites along the Ria Formosa, covering the water bodies specified for this system. In situ measurements (temperature, salinity, pH and dissolved oxygen) and water sampling for determination of nutrients, chlorophyll a and suspended solids were taken every 2 h at each site, during complete semidiurnal tidal cycles. Moreover, these data were complemented with in situ data acquired at a high frequency (every 15 min) by a real time observational station deployed at an inner area, close to a main channel, where the anthropogenic pressure is more intense. Data analysis clearly depict a spatial variability pattern along the Ria Formosa, as well as a temporal heterogeneity, influenced by the contribution of precipitation, sediments, wind and water exchanges with the adjacent ocean. Between sampling sites, the lowest variability of water quality parameters occurred at the boundary coastal station, at the main inlet, in permanent connection with the ocean, while the maximum variability was found at both the lagoon edges, mainly due to the shallowness of the water column. Temporally, the highest concentrations of nutrients were obtained during the Wet/rainy conditions survey, under the influence of runoff. The lowest concentrations of nutrients were attained during the Summer, except for phosphate, due to consumption by phytoplankton. Although the sampling frequency along time has been limited, Ria Formosa water quality data from the last 40 years shows a decreasing trend in nutrients concentration and a marginal increase of dissolved oxygen, suggesting a water quality improvement over time, in contrast with other coastal lagoons that are showing a water quality deterioration due to an increasing anthropogenic pressure. Altogether, these are relevant aspects to consider regarding Ria Formosa present and future management, including climate change and anthropogenic pressures susceptibility assessment and to use them within an international context by comparison with other similar systems. • Spatial and temporal variability of the water quality of Ria Formosa was assessed. • Spatially, the lagoon edges and the estuarine region present the highest nutrients. • Land runoff during Wet survey can justify peak nitrate and ammonium concentrations. • Diffusion processes from the sediments can explain phosphate maximum during Summer. • Temporally, water quality of Ria Formosa has been improved over the last 40 years. [ABSTRACT FROM AUTHOR]

Abstract: The role of benthic sandy ecosystems in mitigating loads carried by Submarine Groundwater Discharge (SGD) to coastal marine ecosystems is uncertain. Benthic biogeochemical mediation of -rich submarine groundwater discharge was studied at the seepage face of a barrier island site in the Ria Formosa coastal lagoon (Southern Portugal). Preliminary analysis of porewater distributions at the seepage face during discharge indicated that benthic biogeochemical processes could significantly affect the fluxes of groundwater-borne into the lagoon. In order to discriminate between the relative contribution of transport and reaction processes to shape and concentration range evidenced by in-situ porewater gradients, an advection-dispersion-reaction (ADR) model of diagenesis was applied to describe porewater profiles obtained in March, June, September and December 2006. Good agreement between modeled and measured profiles was obtained. Model-derived apparent benthic nitrification and reduction rates ranged from 0.01 to 5.2 mmol m−2 h−1, sufficient to explain gross observed changes in fluxes arriving at the seepage face (up to 70% within the surficial 20 cm depth layer). Results of the analysis indicated that the upper limit of the seepage face promoted mitigation of fluxes to the lagoon throughout the year. In contrast, the lower limit of the seepage area promoted net amplification of the fluxes into the lagoon in June and September. These results will help constrain further work aiming to clarify the role of permeable sediments in mitigating nitrogen loading of coastal ecosystems. [Copyright &y& Elsevier]

Frias, P., Horta, J., Almeida, L.P., Pacheco, A., Ferreira, Ó., 2013. Development of a WebGIS tool to determine tidal inlet evolution. In: Conley,D.C., Masselink, G., Russel, P.E.and O'Hare, T. J. (eds.) Research into the consequences of engineering works on the long-term behaviour of inlet systems has been hindered by the absence of suitable datasets, the shortcomings of existing formulae and evaluation tools. Cross-sectional channel areas adjust to hydrodynamics and sediment transport conditions. The impacts of a new inlet on the adjacent shoreline can be unpredictable and are difficult to quantify. This paper presents the development of a Web GIS tool (WebInletAnalyst) that allows any coastal or hydraulic engineer to autonomous extract the evolution of key tidal inlet parameters such as minimum cross-section area, inlet width, maximum depth and migration distance, from a set of bathymetric charts and raw data surveys. The tool is built on a web interface written and compiled using source codes. The tool was applied to a test case (Ancão Inlet, Ria Formosa, Portugal) using available datasets and compared with results from other studies, following the Coastal Engineering Manual guidelines. Overall results showed that mean differences between manual and automate techniques were small and randomly distributed. The user' definition of the location and orientation of minimum cross-section profile affects the accuracy of the tool. Further improvements on the available web interface tool are being tested to allow a magnified view of the inlet channel area and a better precision on sketching the minimum cross-section profile. The tool will be ultimately made available on Python code, allowing future further improvements and adaptations by the scientific community. [ABSTRACT FROM AUTHOR]

Abstract: There are numerous studies dealing with larvae of Small Pelagic Fish (SPF), but only a few have actually addressed advanced larval phases. Temperate coastal lagoons are particularly understudied, due to the absence of standard method to capture advanced larval fish in these near shore shallow habitats. Accordingly, this study aims to describe abundances, nutritional condition and in situ growth of post-flexion (SPF) from the Ria Formosa, a tidal coastal lagoon in southern Portugal. The nutritional condition and in situ growth were determined through cohort analysis and standardized RNA:DNA ratio (sRD), complemented with feeding incidence (gut content) and fatty acids (FAs, trophic biomarkers) of postflexion larvae sampled sequentially with light traps, from spring 2005 to summer 2006. Simultaneously, environmental parameters such as water temperature, salinity, dissolved oxygen and chlorophyll a were measured. Post-larvae of SPF were captured through the year in important numbers. The dominant species were Sardina pilchardus (50.7%), Engraulis encrasicolus and Atherina presbyter (11.4%). These results are distinct from those based on adult/juvenile surveys or early planktonic phases in the Ria Formosa where clupeiformes were occasionally reported. Sardines were captured mainly in winter, spring and early summer and anchovies mainly during summer and autumn. Sand smelt, a resident species, was present throughout the year. In the early summer, the three species were present and during this period some diet overlapping occurred, the feeding incidence of the clupeiformes was very low, but atherinids always exhibited full guts reflecting the different gut morphology or indicating different life-cycle strategies. The bulk of the diet was mollusks, crustaceans and appendicularians, for sand smelts, sardines and anchovies, respectively. The results of FA analyses showed some contribution of phytoplankton to SPF in the area. All SPF exhibited higher condition (sRD) and growth rates in summer, which are explained by the adequate temperature and higher planktonic productivity. This is especially relevant because the successful development of postflexion larvae in these nursery areas largely determines the successful recruitment to adult fish populations. [Copyright &y& Elsevier]

Abstract: Coastal shallow lagoons are important ecosystems in terms of their high ecological relevance. They act as buffers of the land–sea interface, providing valuable ecosystem services such as nutrient recycling, decomposition of organic matter and removal of pollutants. Lagoons are regions of restricted exchange, subject to anthropogenic pressures that result in problems such as eutrophication. Because they are shallow, submerged primary producers play a prominent role in lagoon system metabolism. Furthermore, coastal lagoons are particularly vulnerable to global climate change and may act as ‘sentinel systems’. Sea level rise already threatens to overwhelm some lagoons, such as Venice and Moroccan lagoons. Recent observations and studies have shown that a global climate change, especially the warming of the climate system and the sea level rise is unequivocal (IPCC, 2007). Therefore, the dCSTT-MPB model, which deals with nitrogen and chlorophyll concentrations in the water column and within the sediments, was used to explore a range of scenarios that aimed at representing these changes. The tendency of the light limitation due to the sea level rise is the potential degradation of the microphytobenthos community. This reduction would lead to stronger nitrogen fluxes from pore water to the water column, increasing significantly the nitrogen concentrations. No increase in the phytoplankton community was found because it is mainly influenced by the resuspension of microphytobenthos. High nitrogen concentration may be the first indication of an eutrophication event. Nonetheless, nitrogen may be exported to the sea and cause problems in the adjacent coastal waters. The increase in temperature did not lead to significant differences. [Copyright &y& Elsevier]

The dynamics of the seagrass Zostera noltii in established and colonizing meadows were assessed in Ria Formosa lagoon, Southern Portugal. Shoot weight, above:belowground biomass ratio, flowering shoot density, meadow production, and biomass-density relationships were investigated. Results indicate that the species population dynamics differ clearly in different development stages of the meadows. The overall mean of flowering shoot density was five times higher in the colonizing (83 flowering shoots m−2) than in the established meadow (16 flowering shoots m−2), revealing a greater contribution of sexual reproduction during the species colonization process. The temporal variation of the biomass-density relationship in the colonizing meadow showed a cyclic seasonal trajectory, a wider range of data, and a simultaneous peak of biomass and density, suggesting no space limitations constraining the internal packing of shoots during the growing season. In the established meadow, density peaked before biomass in agreement to the dominant role of the clonal architecture of seagrasses in the configuration of closed meadows, suggesting the occurrence of self-thinning and/or regulation of ramet formation. Slope of the biomass-density relationships was similar in the established and colonizing meadows, generally suggesting similar nutritional conditions, regardless of their muddy and sandy sediments. Plants of the colonizing meadow invest mainly on the belowground fraction (above:belowground biomass ratio <1), as meadow expansion is mainly controlled by the elongation of horizontal rhizomes. The annual total production (1163 g C m−2 year−1) and the biomass turnover (34.8 year−1) were also higher in this meadow, corroborating the high investment of the species during the meadow expansion. The faster biomass turnover of the colonizing meadow implies a more limited capacity to accumulate biomass, indicating a greater exportation of organic carbon and nutrients to the coastal area. The different biomass turnover rates suggest different trophic and structural roles of Z. noltii communities in established and colonizing meadows. [ABSTRACT FROM AUTHOR]

Abstract: This study investigates the effect of entrance/exit losses on the cross-sectional stability of double inlet systems. The inlet is in equilibrium when the sand transport into the inlet equals the sand transport out of the inlet. The velocity amplitude corresponding with the equilibrium cross-sectional area is referred to as the equilibrium velocity (∼1 m s−1). This equilibrium is stable when after a perturbation the cross-sections of both inlets return to their original equilibrium value. The amplitudes of the inlet velocities are obtained using a lumped-parameter model in which the basin water level fluctuates uniformly (pumping mode) and where the inlets are schematized to prismatic channels. The system is forced by a semi-diurnal tide, where amplitude and phase may differ between the two inlets. Previous studies concluded that for double inlet systems no stable equilibriums can be found. However, in these studies entrance/exit losses were neglected. In the present study entrance/exit losses are included in the dynamic equation of the inlets. Using an analytical model it is shown that entrance/exit losses and a difference in the two ocean tidal amplitudes are a prerequisite for the existence of stable equilibriums. Furthermore, the effects of the addition of bottom friction and inertia to the dynamic equation are investigated using a mathematical continuation method. The results show that, provided entrance/exit losses are considerably larger than bottom friction and inertia, stable equilibriums are possible. These conclusions are supported by observations in the Ria Formosa, southern Portugal. Care should be taken in using the stability model described in this paper as a predictive tool due to simplifications in the model and the uncertainty in determining certain parameter values including inlet length, entrance/exit loss coefficient, bottom friction factor and equilibrium velocity. To alleviate these shortcomings suggestions are made for future research. [Copyright &y& Elsevier]

Ria Formosa is a Region of Restricted Exchange given its limited connection to coastal water circulation. Furthermore, it is subject to several anthropogenic activities that can lead to an increase in nutrients and potentially to eutrophication. Previous studies have shown the importance of the benthic compartment, specifically the microphytobenthos (MPB) in this shallow coastal lagoon. The dCSTT-MPB model [new version of the dynamic Comprehensive Studies Task Team (dCSTT) model] here described couples the benthic and pelagic compartments. Due to the shallowness of the system, the benthic microalgae are one of the most important primary producers of the system. Preliminary results of the model show a large biomass of benthic microalgae, which strongly influences the pelagic chlorophyll concentration by resuspension. However, algae concentrations in the water column are relatively small due to the high flushing rate of the lagoon. The MPB community is mainly supported by nutrients in the pore water. A sensitivity analysis (SA) has revealed that the factors associated with the benthic compartment were the most important and sensitive to changes. Porosity, benthic chlorophyll recycling, loss of MPB due to grazing and the yield of microphytobenthic chlorophyll from nitrogen were some of the most sensitive parameters, as well as the ones associated with decay of particulate organic nitrogen. The development of our dCSTT-MPB model has itself provided insights into benthic function. [ABSTRACT FROM AUTHOR]

Abstract: We investigated the effects of ocean acidification on juvenile clams Ruditapes decussatus (average shell length 10.24mm) in a controlled CO2 perturbation experiment. The carbonate chemistry of seawater was manipulated by diffusing pure CO2, to attain two reduced pH levels (by −0.4 and −0.7 pH units), which were compared to unmanipulated seawater. After 75days we found no differences among pH treatments in terms of net calcification, size or weight of the clams. The naturally elevated total alkalinity of local seawater probably contributed to buffer the effects of increased pCO2 and reduced pH. Marine organisms may, therefore, show diverse responses to ocean acidification at local scales, particularly in coastal, estuarine and transitional waters, where the physical–chemical characteristics of seawater are most variable. Mortality was significantly reduced in the acidified treatments. This trend was probably related to the occurrence of spontaneous spawning events in the control and intermediate acidification treatments. Spawning, which was unexpected due to the small size of the clams, was not observed for the pH −0.7 treatment, suggesting that the increased survival under acidified conditions may have been associated with a delay in the reproductive cycle of the clams. Future research about the impacts of ocean acidification on marine biodiversity should be extended to other types of biological and ecological processes, apart from biological calcification. [Copyright &y& Elsevier]

Abstract: Overwash is an important process in barrier island evolution and its effects on the barrier morphology and sedimentology have been widely studied. However, the short-term sediment dynamics of overwash processes are not well known due to the lack of specific field studies. This paper presents field data that clarify the sedimentary dynamics of overwash processes on different washover morphologies, and determine the factors leading to non-storm overwash occurrence. Two fieldwork campaigns were undertaken during overwash events: GO.1 (winter of 2001), and GO.3 (winter of 2003), on western Barreta Island (Algarve, Portugal). The fieldwork included measurements of oceanographic conditions, overwash flows, morphology variations, mixing depth and sediment transport paths using tracers. The sediment dynamics induced by overwash varied according to the washover morphology (washover plain versus washover lobe). The sediment transport inside the washover plain was different for the two fieldwork campaigns (average mixing depth of 13cm for GO.1 and 6cm for GO.3); however it had similar main stages: Stage 1 — crest accretion, Stage 2 — onshore transport, and Stage 3 — dynamic equilibrium. The sediment transport inside the washover lobe can be characterised by one onshore flow stage, with erosion of the mouth and channel, and accretion on the washover fan. The main factors governing the occurrence of non-storm overwash in the study area were the combined occurrence of: (1) typical winter waves, (2) spring high tides, (3) washover crest below the high-tide level +2m, and (4) absence of prominent beach berm. This study proved that when the proper conditions are generated, non-storm overwash has sediment transport comparable to storm overwash and therefore may be significant for barrier evolution. Further field studies of overwash are needed, principally for more detailed overwash flow velocity measurements, high-frequency morphologic surveys, and barrier groundwater measurements. [Copyright &y& Elsevier]

Abstract: Although it is generally acknowledged that most multiple inlets are unstable and cannot coexist, there is evidence to suggest that such inlets can indeed be stable over decadal time scales. Multiple-inlet systems servicing a single embayment, in contrast to single-inlet systems, confer particular hydrodynamic characteristics such as the potential existence of residual discharges and currents between the inlets. This paper presents detailed measurements of hydrodynamic variables obtained over complete spring and neap tidal cycles in a multiple-inlet system in Southern Portugal (Ria Formosa). The results indicate that the two main interconnected inlets servicing an embayment can coexist, at least over a time scale of several decades. However, their coexistence cannot be explained simply using empirical equilibrium relations or inlet hydraulics. Although residual flow between the inlets appears to play an important role enhancing their stability, it is the availability of sediment stored in the ebb-tidal deltas (and its capacity to be carried into the inlets during storm events) that ultimately dictates the overall equilibrium, independently of the flushing capability provided by the hydraulics. Such movement of sediment leads to the obstruction of the inlet channels, thereby affecting the hydraulic efficiency and eventually leading to inlet closure in the long term. The results augment existing knowledge concerning multiple-inlet systems and improve understanding of their short- to medium-term stability. [Copyright &y& Elsevier]

The plant reproductive effort, the seed germination rate and the seedling survival and development of Zostera marina (eelgrass) were assessed in four populations (Fuzeta, Culatra, Barrinha and Armona) at the species’ southern distribution limit in the Eastern Atlantic, the Ria Formosa lagoon. Germinated seeds were individually placed in Petri dishes with natural sandy sediments and kept in a culture chamber at the same temperature and salinity conditions as the natural environment. In addition, seeds from three different depths of Fuzeta population were cultivated in outdoor mesocosms. The populations of Fuzeta and Barrinha showed higher seed production and the seeds produced were heavier than the other populations. The germination of the seeds both in the laboratory and in the outdoor tanks began c. 8–12 weeks after the collection of the flowering shoots at a water temperature of 22 °C. The spontaneous germination in the laboratory (2.4–5.3%) and in the mesocosm experiment (5.6–8.9%) was low and from all the germinated seeds (n = 20) only three reached the seedling stage. The spontaneously germinated seeds from Fuzeta survived for a longer period than those from Barrinha, but only the germinated seeds of Barrinha reached the seedling stage (one-leaf seedling stage). In outdoor tanks, higher seed germination and earlier seedling emergence (2 weeks after seeding) and survival (for 208 days) occurred for the seeds obtained from the shallow meadow. The reproductive effort of Z. marina populations of Ria Formosa showed that flowering shoots and seed traits are site-specific. The low reproductive success indicated by the low germination and seedling survival suggests a bottleneck in the species’ reproductive cycle that may account for the scarce presence of the species in Ria Formosa lagoon. The high water temperatures of Ria Formosa in winter may partly explain this bottleneck. Increased temperatures due to climate change may reduce even further the sexual reproduction of Z. marina in its southern distributional limit in the Eastern Atlantic. [ABSTRACT FROM AUTHOR]

Abstract: The population dynamics of the seagrass Cymodocea nodosa was investigated in three meadows differently affected by the artificial relocation of an inlet in the western sector of the Ria Formosa lagoon, southern Portugal. One meadow was subjected to increasing currents that caused erosion, another one was subjected to an initial episode of burial and a third meadow was undisturbed by the inlet opening. The hydrodynamic/sedimentary condition of meadows was assessed through comparative sediment analysis between the meadow and the adjacent unvegetated area. The studied C. nodosa meadows clearly reflected the resultant hydrodynamic changes and consequent sedimentary disturbances caused by the inlet opening, eleven months prior to sampling. In all meadows except the eroded one, C. nodosa promoted the accumulation and stabilization of sediments with grain-size dominated by a mode of 2.75 ϕ, much finer than the surrounding sediments, which grain-size was dominated by modes of 0.75–1.25 ϕ. Under the strong currents of the eroded meadow, the sediment was much coarser (mode of 0.75 ϕ), had less organic matter content and was not significantly different from the adjacent unvegetated area. A lower horizontal rhizome elongation, higher shoot mortality and lower shoot recruitment was observed at the eroded meadow indicating a strong population regression. Based on the sediment grain-size of the eroded meadow, it was inferred that the current velocity thresholds for C. nodosa decline occur at water current >60 cm s−1. Sediment burial resulted in longer leaf sheaths, higher vertical and horizontal rhizome elongation, lower shoot age, lower total biomass and higher shoot recruitment, which suggests population recovery after disturbance. The net recruitment of all studied meadows, including the undisturbed one, was negative, even though the buried meadow was close to zero. If environmental conditions will remain the same, all studied meadows are predicted to decline to extinction. Results thus suggest that the inlet relocation may alter the landscape distribution of C. nodosa meadows in Ria Formosa, but it was not the main cause of C. nodosa decline. [Copyright &y& Elsevier]

Abstract: The yield of phytoplankton chlorophyll from nitrogen is a useful parameter in the study of eutrophication of coastal waters, providing the link between chlorophyll formation and nutrient consumption. This parameter has been estimated for microphytobenthos from Ria Formosa lagoon on the south coast of Portugal with a series of three experiments conducted in May and September 2007. Six sediment cores were collected from Ria Formosa in acrylic cylinders and cork stoppers were placed in the bottom. Water samples were collected in large containers and prepared (filtered and enriched) to be pumped to the top of the sediment inside the acrylic cylinders, which are the microcosms of the experiments. Microcosms were isolated to avoid water exchanges and placed in large tanks full of water to maintain temperature stability. Experiments were run for 5 to 9days in a continuous diluted nutrient enriched system. One of the experiments was carried out with half the microcosms in the dark to evaluate the nutrient fluxes between the sediment and the water column, when no algal growth is expected. Nutrient fluxes of muddy sediments, during the two last days of the experiment in the dark were estimated to be 0.1015μmolcm−2 d−1 for nitrogen, −0.0015μmolcm−2 d−1 for phosphorus, and 0.1395μmolcm−2 d−1 for silicon. The yield of chlorophyll was determined to be between 3.65 and 4.11μgchl(μmolN)−1 from nitrogen and between 4.03 and 4.77μgchl(μmolSi)−1 for silicon in muddy sediments. It was not possible to determine the yield from phosphorus. These values are higher than for phytoplankton which may be due to physiological reasons, or due to the presence of a smaller fraction of microheterotrophs, which would divert nutrients. For sand, smaller yields were obtained but it is likely that this was mainly due to the fact that the values of the sediment fluxes used were the ones obtained for mud, which are higher than they should be for sand. This extra input of nutrients is considered to be taken up by algae, thereby decreasing the value of the yield. Therefore, reliable chlorophyll yield estimates for sand could not be obtained. [Copyright &y& Elsevier]

Abstract: Acoustic telemetry and standard tag-recapture were used to determine the home range and residency of juveniles and sub-adults of Diplodus sargus and Diplodus vulgaris in the Ria Formosa (Portugal) coastal lagoon. Maximum time between recaptures for the standard tag-recapture method was 128 days for D. sargus and 30 days for D. vulgaris. The majority of the fish were recaptured in the vicinity of the tagging location. Fish tagged with acoustic transmitters had a maximum period of time between first and last detections of 62 days for D. sargus and 260 days for D. vulgaris. Minimum convex polygons areas ranged between 148 024m2 and 525 930m2 for D. sargus and between 23 786m2 and 42 134m2 for D. vulgaris. Both species presented a high residency index between first and last detections. Two D. sargus tagged with acoustic tags were recaptured by fishermen outside the coastal lagoon at distances of 12km and 90km from the tagging position, providing evidence that this species leaves the Ria Formosa during the winter time for the adjacent coastal waters. The results of this study reinforce the importance of Ria Formosa as a nursery for D. sargus and D. vulgaris in the south coast of Portugal. [Copyright &y& Elsevier]

The challenge on implementation of the EU Water Framework Directive (WFD) (2000/60/EC) fosters the development of new monitoring approaches. The directive promotes the use of modelling techniques to assist all phases of the process, from characterization and establishment of reference conditions to identification of pressures and assessment of impact. This work is based on the above principles. A classical monitoring of the water status of the main transitional water bodies of Algarve (South of Portugal) is combined with advanced in situ water profiling and hydrodynamic, water quality and ecological modelling to build a complete description of the system. The aim is to demonstrate a methodology where traditional monitoring and modelling tools can be joined together to draw a holistic picture. The results show that globally the water bodies present a good trophic status. Eutrophication symptoms are not generalized. Due to physical transport and dispersion, nutrient enrichment is not the only factor limiting growth; residence time is also an important factor. Some confined regions with high residence times are at present endangered by point and diffuse sources of pollution. The microbiologic impact of waste water treatment plants (WWTP) is confined to regions between 500m and 1 km from the discharges. [ABSTRACT FROM AUTHOR]

Abstract: To investigate both the role of tides on the timing and magnitude of Submarine Groundwater Discharge (SGD), and the effect on benthic nitrogen biogeochemistry of nitrate-enriched brackish water percolating upwards at the seepage face, we conducted a study of SGD rates measured simultaneously with seepage meters and mini-piezometers, combined with sets (n =39) of high resolution in-situ porewater profiles describing NH4 +, NO3 −, Si(OH)4 and salinity distribution with depth (0–20 cm). Sampling took place during two consecutive spring tidal cycles in four different months (November 2005, March, April and August 2006) at a backbarrier beach face in the Ria Formosa lagoon, southern Portugal. Our results show that the tide is one of the major agents controlling the timing and magnitude of SGD into the Ria Formosa. Intermittent pumping of brackish, nitrate-bearing water at the beach face through surface sediments changed both the magnitudes and depth distributions of porewater NH4 + and NO3 − concentrations. The most significant changes in nitrate and ammonium concentrations were observed in near-surface sediment horizons coinciding with increased fraction of N in benthic organic matter, as shown by the organic C:N ratio. On the basis of mass balance calculations executed on available benthic profiles, providing ratios of net Ammonium Production Rate (APR) to Nitrate Reduction Rate (NRR), coupled to stoichiometric calculations based on the composition of organic matter, potential pathways of nitrogen transformation were speculated upon. Although the seepage face occasionally contributes to reduce the groundwater-borne DIN loading of the lagoon, mass balance analysis suggests that a relatively high proportion of the SGD-borne nitrogen flowing into the lagoon may be enhanced by nitrification at the shallow (1–3 cm) subsurface and modulated by dissimilatory nitrate reduction to ammonium (DNRA). [Copyright &y& Elsevier]

Abstract: Microphytobenthos (MPB) are an important, yet highly variable, component of productive shallow systems and intertidal areas. Samples were collected from Ria Formosa, Portugal, to assess the temporal and spatial variability of microphytobenthic chlorophyll in two types of intertidal sediment: mud and sand. Chlorophyll pigments were measured spectrophotometrically after freeze-drying and extraction into an acetone–water mixture. Time-series of superficial chlorophyll measured at two sites during 2006–2007 showed no obvious seasonal peaks. A truncated Fourier series was fitted to the time-series data. Seasonality was very weak: only 5% of the estimated total variance could be explained by annual cycle components up to 3year−1, while 25% was explained by waves with periods from 14 to 91days. The residual error of the Fourier series was partitioned into within-day variance (61%) and other components (9%). The within-day variation was made up of roughly equal contributions from: (i) variability associated with sampling within-sites; and (ii) differences between-sites. There were no significant correlations between MPB chlorophyll and tidal range, wind speed, solar irradiance, water temperature and salinity and water nutrient concentrations. Sediment type was once more confirmed to be a key factor to MPB spatial variability. These results are discussed in relation to processes controlling the distribution of benthic microalgae in Ria Formosa, and their implications considered in relation to on-going work to understand and model the role of microphytobenthos in eutrophication in such water bodies. [Copyright &y& Elsevier]

This work describes the application of hydrodynamic (ELCIRC) and transport (VELA and VELApart) models to the Ria Formosa lagoon (Portugal) to study the impact of the relocation of the Ancão Inlet. Located in the south of Portugal, this lagoon is a mesotidal barrier island system that communicates with the sea through 6 inlets. The Old Ancão Inlet was artificially closed and the New Ancão Inlet was relocated into a westward position. This work investigates the hydrodynamic patterns and the potential pathways of tracers in Ria Formosa in two distinct configurations: before and after the Ancão Inlet relocation. The hydrodynamic model was successfully calibrated and validated against elevation, velocity and inlet discharges data, accurately reproducing the tidal propagation. The inlet relocation increases the magnitude of tidal currents, residual velocities and the tidal prism across the bar, suggesting a better stability. The tracers transport simulations suggest enhanced water exchanges through the Ancão Inlet and smaller residence times in the western part of Ria Formosa with the present configuration. Overall, it is concluded that the Ancão Inlet relocation had a positive contribution towards increasing the water renewal of the western part of the lagoon, thus decreasing its vulnerability to pollution. [Copyright &y& Elsevier]

The objective of this work is to determine the relative importance of different processes (swash, overwash, aeolian, and lagoon) affecting sediment dynamics in barriers with frequent overwash. Aerial photographs, topographic surveys (with real-time kinematic global positional system), and sample collection were undertaken on Barreta Island (Ria Formosa barrier islands, Portugal). Wave and tidal data were also analysed during a 3-year monitoring period (2001-2004). This 3-year period represents the typical wave conditions of this region. Historical barrier evolution was characterised for the 1947-2001 period. Up until 1996, the supratidal barrier changed from barred sand to fully developed dunes. In 2001, a wide washover plain had developed and an updrift tidal inlet (Ancão Inlet) was migrating toward the study area. Between 2001 and 2004, the study area had three geomorphological sectors. Sector A (westernmost) showed the widest beach berms that developed because of welding of swash bars of Ancão Inlet. Sector B had the widest washover and developed embryonic dunes with well-sorted medium sands. In sector C (easternmost), overwash was more frequent, and induced the deposition of 57 m3/m of sediments (the coarsest of the barrier). Globally, barrier volume variation was mostly due to swash (83%); however, net barrier accretion was 88% induced by overwash. Barrier volume variation was more related to Ancão Inlet evolution than to the seasonality of wave climate. A four-stage conceptual model of barrier evolution under frequent overwash is presented: beach erosion; dune destruction, and formation of washover plain; frequent overwash; and dune development. [ABSTRACT FROM AUTHOR]

Abstract: The seasonal plasticity of individual Zostera noltii architectural, reproductive and elemental content features, of plant epiphyte load and of meadow biomass–density relationships was investigated along a vertical intertidal gradient at Ria Formosa lagoon, southern Portugal. The vertical variability of the seagrass environment was evident in the sediment characteristics, which showed coarser grain size, less organic matter, lower N content and higher ammonium concentration in the low intertidal than in medium and high intertidal. A clear vertical differentiation in Z. noltii morphology was observed from longer and wider leaves, longer and wider internodes and shorter roots at low intertidal, to shorter and narrow leaves, shorter and narrower internodes and longer roots at high intertidal. The leaf size was negatively related to light availability and positively related to nutrient availability whereas the root size was negatively related to nutrient availability. The lower leaf N and P content found in low intertidal plants may reflect a dilution effect of the nutrients due to higher growth rates. Lower N content of low intertidal leaves supports previous findings that the nitrate reductase activity is lower in plants from this level. The higher epiphyte load observed in Z. noltii leaves of the low intertidal may be a consequence of the lower exposure period, but also of higher hydrodynamics that increase the availability of nutrients. No evidence of the influence of the intertidal level on the flowering shoot density was found. The cyclic temporal pattern of the biomass–density relationship was much wider at low and medium intertidal than at high intertidal. At low intertidal, the decline in shoot density during fall and winter was coincident with a biomass decrease and its increase in spring and summer coincided with the biomass increase. In medium and high intertidal, the biomass and density seasonal variations were decoupled. As a result, only at low intertidal there was a significant positive relationship between biomass and density. This suggests that Z. noltii population structure along the intertidal is regulated by different factors. Light is probably the most important factor regulating the population structure in the low intertidal, whereas desiccation is probably the main factor regulating the populations in upper intertidal. Zostera noltii showed a considerable plasticity at a physiological-, plant- and population-level along the intertidal zone, indicative of the species acclimation to the steep environmental gradient of this particular ecosystem. [Copyright &y& Elsevier]

The purple dye murex, Bolinus brandaris (Linnaeus, 1758), is a muricid gastropod common throughout the Mediterranean and along the Moroccan and Portuguese Atlantic coasts. In the present study, we confirmed the diploid chromosome number of 2 n = 70 for this species, and established for the first time the karyotype, which comprised 12 metacentric, 15 submetacentric and eight subtelocentric chromosome pairs. To facilitate cytotaxonomic comparisons, we carried out a comparative karyological analysis through multidimensional scaling between B. brandaris and three other 2 n = 70 muricid species ( Hexaplex trunculus, Ocenebra erinaceus, and Stramonita haemastoma) for which chromosomal measurements have been previously published. The interpretation of the ideograms and the statistical analysis highlighted the closest similarity of B. brandaris and H. trunculus compared to S. haemastoma and O. erinaceus. Indeed, B. brandaris and H. trunculus showed the smallest dissimilarities both for relative length and arm ratio, with O. erinaceus presenting intermediate values, whereas the highest dissimilarities were found between H. trunculus and S. haemastoma for both data. The karyotypes of B. brandaris and H. trunculus (subfamily Muricinae) presented the highest proportions of metacentric chromosomes compared to the other two muricids analysed, suggesting that those karyotypes could be considered primitive within the 2 n = 70 Muricidae studied so far. © 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 96, 185–193. [ABSTRACT FROM AUTHOR]

Abstract: The faunal communities of four intertidal habitats namely sand, mud, seagrass (Zostera noltii) and seagrass patches (mixSM) of a temperate coastal lagoon, Ria Formosa (southern Portugal), were sampled. A total of 47 species were taken in 428 bottomless drop sampler samples, with the highest number of species and the more commonly occurring species belonging to the Mollusca phylum. The dominance of these gastropod species underlines the importance of the grazing food chain in these habitats. Bittium reticulatum was the most abundant species, being especially abundant in the seagrass habitat. The most frequent and highest biomass species in the community was Carcinus maenas, a predator that makes use of the available resources and that is adapted to the highly variable intertidal environment. Pomatoschistus microps was the most abundant fish species, with highest densities in the mud habitat, which demonstrates an ability to occupy a low depth area. The seagrass habitat had the highest diversity, abundance and biomass, followed by the mixSM habitat and was different from all the others. Assemblages were highly influenced by the presence of vegetation, providing forage and refuge from predation. A well defined summer group was identified in all habitats. These results highlight the importance of seagrass beds and the idea that their decrease implies the decrease of lagoon production through the impoverishment of the trophic structure of the lagoon. [Copyright &y& Elsevier]

Abstract: Short-time site fidelity and movements of gilthead sea bream (Sparus aurata) in a coastal lagoon were determined using passive acoustic telemetry. Nine fish, ranging from 20.1 to 32.5cm total length, were surgically implanted with acoustic transmitters and monitored for up to 179 days. Minimum convex polygon areas ranged from 18,698.6m2 to 352,711.9m2. Home range sizes were small, with individuals using core areas on a daily basis. However, these core areas shifted within the study site over time towards the opening to the sea. Two different diel behaviors were recorded, with some individuals more active at night and others during day time. Some individuals also demonstrated homing abilities, returning to the capture site after being released more than 4km away. [Copyright &y& Elsevier]

Abstract: Shorelines occurring along restricted fetch environments, such as the backsides of barrier islands, are extremely diverse with respect to their morphologic characteristics and evolution. In order to better understand the morphodynamic evolution of backbarriers and the associated implications for entire barrier systems, this study proposes a backbarrier evolutionary categorisation model based on the development of two types of index: backbarrier evolution tendency and backbarrier maturation condition. The proposed characterisation system is applied to the Ria Formosa backbarrier (located in southern Portugal) for the period 1947 to 2001. Cross-shore and longshore backbarrier trends in Ria Formosa suggest a shrinking of the lagoon system as a consequence of a decrease in the coastal length of the backbarrier coastline and a landward displacement of it. Even though some of the backbarriers examined were found to be in an immature state, the results obtained illustrate a maturing trend for the system overall. Barriers in Ria Formosa fall into two main evolutionary categories: backbarrier reduction and backbarrier growth. This means that neither smoothing nor branching has been significant and therefore that backbarrier recent evolution is closely related to barrier coast length. Application of the proposed characterisation to the Ria Formosa case study has helped reveal backbarrier evolutionary trends and therefore should be of use in the management of backbarrier systems. [Copyright &y& Elsevier]

Abstract: The abiotic disturbance of urban wastewater discharge and its effects in the population structure, plant morphology, leaf nutrient content, epiphyte load and macroalgae abundance of Zostera noltii meadows were investigated in Ria Formosa coastal lagoon, southern Portugal using both univariate and multivariate analysis. Four sites were assessed, on a seasonal basis, along a gradient from a major Waste Water Treatment Works (WWTW) discharge to a main navigation channel. The wastewater discharge caused an evident environmental disturbance through the nutrient enrichment of the water and sediment, particularly of ammonium. Zostera noltii of the sites closest to the nutrient source showed higher leaf N content, clearly reflecting the nitrogen load. The anthropogenic nutrient enrichment resulted in higher biomass, and higher leaf and internode length, except for the meadow closest to the wastewater discharge (270m). The high ammonium concentration (158–663μM) in the water at this site resulted in the decrease of biomass, and both the leaf and internode length, suggesting a toxic effect on Z. noltii. The higher abundance of macroalgae and epiphytes found in the meadow closest to the nutrient source may also affect the species negatively. Shoot density was higher at the nutrient-undisturbed site. Two of the three abiotic processes revealed by Principal Component Analysis were clearly related to the WWTW discharge, a contrast between water column salinity and nutrient concentration and a sediment contrast between both porewater nutrients and temperature and redox potential. A multiple regression analysis showed that these abiotic processes had a significant effect on the biomass-density dynamics of meadows and on the overall size of Z. noltii plants, respectively. Results show that the wastewater discharge is an important source of environmental disturbance and nutrients availability in Ria Formosa lagoon affecting the population structure, morphology and N content of Z. noltii. This impact is spatially restricted to areas up to 600m distant from the WWTW discharge, probably due to the high water renewal of the lagoon. [Copyright &y& Elsevier]

Submarine Groundwater Discharge (SGD) has been frequently ignored as a nutrient source to marine ecosystems because it is difficult to identify and quantify. However, recent studies show its ubiquity and ecological importance to the coastal zone, particularly when associated with contaminated continental aquifers. The Ria Formosa is a coastal lagoon located in the south of Portugal and surrounded by an intensely farmed area. Following a 12-month field study using seepage meters, we identified groundwater discharge in the intertidal zone of the lagoon. The seeping fluid was a mixture of two water types: one with low salinity and high nitrate concentration and another similar to local seawater. Based on the integration of monthly seepage rate measurements throughout the year, we estimate the mean discharge of submarine groundwater into the lagoon to be 3.6 m3 day−1 per linear meter of coastline with freshwater contributions (per volume) ranging from 10% to 50%. The results of this study suggest a continental origin for the freshwater component, thus linking the biogeochemical cycles in the lagoon to anthropogenic activities taking place in the neighboring coastal plain. We further identify SGD as an important nutrient source to the Ria Formosa, estimating annual loads of 36.2 mol (0.507 kg) of Nitrogen, 1.1 mol (0.034 kg) of Phosphorus and 18.6 mol (0.522 kg) of Silicon per meter of coastline. Based on these results, we suggest that SGD is a potential contributor to the observed nutrification status of the Ria Formosa lagoon. [ABSTRACT FROM AUTHOR]

Abstract: Fish communities of the Ria Formosa coastal lagoon (south Portugal) were sampled on a monthly basis with a beach seine at 4 sites, during two different time periods: 1980–1986 and 2001–2002. Community indices, species ranking and multivariate analysis were used in order to identify changes in the fish community between the two time periods. A total of 153,511 fish representing 57 taxa were recorded. Although species composition was very similar for both sampling periods, multivariate analysis performed on annual species abundance in number and weight revealed differences in fish community structure between the two periods. Structural changes in fish community were related mostly to a sharp decrease in the abundance of Mugilidae from 1980–1986 to 2001–2002. These changes were probably associated to a decrease in organic matter contents and nutrients concentrations due to improvements in sewage treatment and better water circulation inside the lagoon. The changes in fish community structure are more evident in the inner areas of the lagoon than near the inlet. The association between changes in sewage patterns and changes in the ichthyofaunal community structure reinforces the importance of fish communities as a biological indicator of human induced changes in marine systems. [Copyright &y& Elsevier]

The spatial and temporal variation of phytoplankton pigments in the western part of Ria Formosa, Portugal, was investigated between September 2000 and July 2002. Sampling stations included the ocean boundary (Ancão inlet) and two different landward boundary situations: 1) the shallow westernmost "blind end" of the lagoon (Ponte) and 2) near a main sewage outlet (Ramalhete). Nutrient concentrations were higher during the first year of sampling but were lower than those recorded in previous studies. This decrease in the concentration of nutrients was possibly the result of the 1997 relocation of the Ancão inlet, which allowed better water circulation in the lagoon. Throughout this study, concentrations of chlorophyll a determined by high-performance liquid chromatography were consistently low. Inter-annual variability in the pattern of chlorophyll a concentration was observed in the form of a bimodal peak (spring/summer and autumn) between September 2000 and June 2001 and more uniform concentrations from September 2001 until July 2002. Principal component analysis of the concentrations of all pigments did not indicate any spatial- or tidal-related variations but did show that pigment concentrations varied over time. Partial least squares analysis corroborated this temporal shift of the phytoplankton pigment abundance and composition and showed that these shifts could be linked to certain environmental variables. Fucoxanthin was the dominant accessory pigment and was strongly correlated with chlorophyll a. Other marker pigments present in lower concentrations included chlorophyll b, 19'-hexanoyloxyfucoxanthin, neoxanthin, alloxanthin, diadinoxanthin, lutein, zeaxanthin, and beta-carotene. PLS analysis was used to infer the dominant phytoplanktonic groups in the lagoon. This analysis established that diatoms and other algal groups with a similar pigment profile dominated the phytoplankton community throughout the year. Cryptophytes were the second most abundant group in the lagoon. The remaining groups, including dinoflagellates, cyanophytes, and chlorophytes, contributed much less to the total algal biomass (generally < 10%). [ABSTRACT FROM AUTHOR]

The concentrations of 16 individual polycyclic aromatic hydrocarbons (PAHs) were measured in sediments from eight locations in the Ria Formosa Lagoon (Portugal) between January and August 1995. Total PAH concentrations were higher in January than in the other months and were related to the higher sedimentary organic carbon content in the winter. The distribution pattern of the individual PAHs was generally dominated by the 4-aromatic ring PAHs, followed by the 2 + 3-aromatic ring PAHs. Fluoranthene, pyrene, and acenaphthene were the most abundant individual PAHs. Principal components analysis revealed that PAHs in the Ria Formosa Lagoon vary by season rather than location. This variation was related to changes in the source term. In the winter, PAH sources were mainly of pyrolytic origin, probably transported by road runoff. In the other months, and especially in the summer, the most important PAH source was related to boat traffic in the Ria Formosa. Source assessment was also conducted using partial least squares analysis, which confirmed the boat traffic origin, although it was inconclusive for the winter samples. [ABSTRACT FROM AUTHOR]