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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]

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]

The clam Ruditapes decussatus was transplanted from a natural recruitment area of Ria Formosa to three sites, surveyed for nutrients in water and sediments. Specimens were sampled monthly for determination of Escherichia coli , condition index and gonadal index. Higher nutrient values in low tide reflect drainage, anthropogenic sources or sediment regeneration, emphasising the importance of water mixing in the entire lagoon driven by the tide. Despite the increase of effluent discharges in summer due to tourism, nutrient concentrations and E. coli in clams were lower in warmer periods. The bactericide effect of temperature and solar radiation was better defined in clams from the inlet channel site than from sites closer to urban effluents. High temperature in summer and torrential freshwater inputs to Ria Formosa may anticipate climate change scenarios for south Europe. Seasonal variation of nutrients and clam contamination may thus point to possible alterations in coastal lagoons and their ecosystem services. [ABSTRACT FROM AUTHOR]

Ria Formosa is a highly productive lagoon in South-Western Europe, supporting 90% of Portuguese clam production. Decreases in shellfish production have been ascribed to deterioration of water quality due to sewage discharges. Nevertheless, a thorough study considering their impact on the whole lagoon system has been missing. This work determined the sewage footprint from the major sewage treatment plants (STP) regarding eutrophication and microbial contamination within a two-year monitoring program. This focused on salinity, oxygen, nutrients, chlorophyll- a and faecal coliforms. Areas closer to sewage discharges showed an evident impact with maximum effects detected at the major STP. However, globally, the Ria Formosa did not show clear eutrophication problems due to high tidal flushing. Ammonium, oxygen, chlorophyll- a and faecal coliforms, unlike the other parameters, showed no seasonality. Microbiological contamination was of great concern and public health issues could be avoided by settling shellfish beds at least 500 m away from discharge points. [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]

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]

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]

Abstract: The SAF (Systems Approach Framework) encompasses the ecological, social and economic components of coastal zones and aims to establish a permanent dialogue between scientists, stakeholders and policy makers working within European coastal zones for developing effective ICZM (Integrated Coastal Zone Management). The objective of the present study is to test the application of the SAF for defining eutrophication management options in the Ria Formosa, Portugal. Stakeholders were identified and the issue of eutrophication was agreed upon. Having defined the virtual system, the conceptual model of the Ria Formosa was developed. The formulation of the conceptual model into a mathematical model representing the ecological, social and economic components of the system is then discussed. The linking variable of the three components within the simulation model, as well as the scenarios to be run are then explored. The role of scientists as facilitators within the deliberation process is discussed, and a format by which the final output package could be disseminated is suggested. This case study demonstrates how the SAF could successfully be applied to the management of eutrophication in the Ria Formosa. It also suggests ways in which this approach may be adapted to address unique coastal systems with specific system characteristics. [Copyright &y& Elsevier]

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]

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: 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]

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]

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: Although mudflats seem relatively planar, closer inspection reveals a succession of meso-topographical features, including consecutive convex and concave meso- and micro-topographical features. The objective of this study was to determine the influence of meso-scale surface sediment morphology on the dynamics of the macroalgae Ulvales (Chlorophyta) and associated macroepifauna in the Ria Formosa tidal lagoon (southern coast of Portugal). Four sites in the Ria Formosa were sampled monthly. Two were located on convex sections (mounds) of the mudflat and the other two on concave sections (depressions). Macroalgae and related macroepifauna were sampled at each station. Biomass was quantified by determination of the ash-free dry weight (AFDW). Data were analysed using the software package ‘PRIMER’ (Plymouth Routines In Multivariate Ecological Research). Results show a clear distinction between convex and concave areas. In convex sections, Enteromorpha dominated, to the point of being the only algal species present during part of the year. Conversely, biomass and dynamics of Enteromorpha and Ulva were almost the same in concave sections. The associated macroepifauna was also different in protruding or depressed sections of the mudflat. In the convex areas, the macroepifauna population showed less diversity and was dominated by the snail Hydrobia ulvae. In concave areas, the species diversity was larger, but dominated in terms of biomass by the amphipod Melita palmata and the gastropod Nassarius pfeifferi. Results of the study indicate that the benthic communities associated with concave or convex features were different. No relevant differences in texture and sediment physico-chemical characteristics were found between convex and concave sections. The inference is that the morphological nature of the bottom in tidal mudflats can act as a structuring agent of benthic communities. [Copyright &y& Elsevier]

Abstract: Coastal hazards affect the majority of sandy shores worldwide, and are responsible for damage to, and destruction of, property and infrastructure. The research reported here presents an integrated method for defining set-back lines associated with coastal hazards on sandy shores for a 50-year period of interest. The method is based on a worst-case scenario approach, the shoreline evolutionary trend being the basis for the initial set-back line determination. Set-back lines are afterwards adjusted by incorporating changes associated with the acceleration of sea-level rise and the evaluation of the consequences (instantaneous shoreline retreat and overwash) of an extreme storm. The method considers different approaches depending on the shoreline behaviour (erosion, dynamic stability or accretion). The set-back lines as determined are plotted over rectified aerial photographs, allowing for a straight-forward interpretation of results. The method was applied to a test case within a barrier island system (Ancão Peninsula, Ria Formosa, Algarve, Portugal). This study area was chosen because it exhibits the three different types of shoreline evolution. The method easily shows the differences in erosion-related coastal hazards along the study area, being an important tool for coastal management. However, the method should be able to be refined at every 5–10 years, for a new 50-year period, by integrating new formulations based on advances in coastal science, and by including updated information and data about the areas to which the method is applied. [Copyright &y& Elsevier]

Abstract: The study concerns the lagoon marshes of the “cul-de-sac” of Ancão (CDSA), situated in the western part of the Ria Formosa. The aim of this article is to propose a quantification of the sedimentary volume in lagoon marshes on the long-, medium- and short-term, to precise the respective part of the natural and human factors driving the sedimentary changes, and to put in perspective the results with the predictions on the rise of sea level. The environmental analysis is based on a set of botanical, morpho-sedimentary and chronological (14C, 137Cs, 210Pb, 226Ra) indicators, on the use of surface marks to measure the vertical growth of saltmarshes, and on the photo-interpretation. Results show that the present available volume of fine-grained sediments represents ∼1,549,215m3. The muddy deposits are concentrated both in the upstream (30%) and downstream (63%) part of the CDSA. The pluri-secular accretion rates (0.4mm/a between 1681 BC and AD 2001) obtained in the Holocene Ludo ria are relatively low, compared with the pluri-10-year accretion rates (8–9mm/a between AD 1941 and AD 2000) calculated from the excess 210Pb and 137Cs activity concentrations. On the short-term (AD 2000–2002), the measures of accretion rates confirm field observations, namely a critical situation where saltmarshes are in dominant erosion. Changes in sedimentary secular trend, spatial heterogeneity of present accretionary deficit and preservation potential of the CDSA marshes are discussed. [Copyright &y& Elsevier]

Inlet relocation is a coastal management tool that, when applied to a migrating inlet, involves the artificial opening of a new tidal inlet along the historic migration path of the inlet. The old inlet is then artificially closed, or it is left open and will eventually close if the new inlet captures the entire tidal prism. Two inlets were relocated in such a manner in Southern Portugal and then were the subject of a monitoring program that included the acquisition of quantitative (topo-bathymetric surveys) data. Data was acquired for 4 years after the relocation at one of the inlets (Ancão Inlet) and for 2 years at the other (Fuzeta Inlet). The data obtained from the monitoring program were analysed together with the wave climate and then compared with historical information on the natural inlets, in order to assess the degree of success of the relocation actions. One of the relocations studied, Ancão Inlet, was considered to be successful even though an initial unexpected behaviour produced some material damage to property. On the contrary, the relocation of Fuzeta Inlet did not have the expected results, and the new inlet was affected by the same problems as the old one.It was found that the most important factor for a relocation action to succeed is the correct choice of the opening location. A theoretical procedure to enhance the possibilities of relocation success is suggested. (1) Hydrodynamic studies are needed in order to determine if the present conditions are similar to the historical ones. (2) The position for the inlet opening is chosen according to the hydrodynamic conditions, but there are other factors to be taken into account, i.e., the historical migration paths and typical inlet width of the natural inlet; the hydrodynamics of the backbarrier; the morphology of the backbarrier and, for multi-inlet barrier island systems, the proximity to adjacent inlets. (3) Once the position is chosen, environmental impact studies should be made in order to assess the risk of the relocation for the ecosystems of the area. Only if the environmental impact studies are favourable should a relocation action be performed. [Copyright &y& Elsevier]

Anthropogenic litter is ubiquitous throughout marine ecosystems, but its abundance and distribution are driven by complex interactions of distinct environmental factors and thus can be extremely heterogeneous. Here we compare the extent of anthropogenic litter pollution at a sheltered lagoon habitat and nearby open coast sites. Monthly surveys over a period of five months showed that both the types and sources of litter always differed significantly between lagoon and open coast sites. Pollution within the lagoon was mainly land-derived and was largely made up of construction materials (70% to 95%). At open coast sites, construction materials represented a minor portion of pollution (4% to 12%) while plastics were the most abundant (82% to 95%). We show that stranded anthropogenic litter in adjacent marine habitats can differ significantly and stress the importance of sampling at appropriate spatial scales to gain realistic insights into the sources of pollution. • We compare anthropogenic litter pollution at a sheltered lagoon and at nearby open coast sites • Monthly surveys show that the types and sources of litter differ substantially between habitats • In the lagoon litter was mainly land-derived, at open coast sites plastic was the main contaminant • We stress the importance of small spatial scale in litter deposition patterns [ABSTRACT FROM AUTHOR]

Plastic waste has become ubiquitous in ecosystems worldwide. Few, recent studies report evidence of coastal vegetated habitats acting as sink for plastics, yet assessments have been completed either for macro or microplastics and focussing on just one type of vegetated habitat. Here, we investigated the role of marine coastal vegetated habitats as sinks for macro (≥5 mm) and microplastics (<5 mm) through a comprehensive, multi-habitat approach. We assessed the occurrence, abundance and physical properties of macro and microplastics in the canopy and superficial sediment of two intertidal (seagrass Zostera noltei , saltmarsh Sporobolus maritimus) and two subtidal (mixed seagrass meadows of Cymodocea nodosa and Zostera marina , rhizophytic macroalga Caulerpa prolifera) habitats in the Ria Formosa lagoon (Portugal). Our results showed that coastal vegetated habitats trapped macro and microplastics in the sediment at variable degrees (1.3–17.3 macroplastics 100 m−2, and 18.2–35.2 microplastics kg−1). Macroplastics accumulated in all vegetated habitat but not in nearby unvegetated areas, yet only S. maritimus habitat presented a significant trapping effect. Microplastics occurred in the sediment of all vegetated and unvegetated areas with similar abundances and high variability. Microplastics, all of type fibre, were recorded on all canopies except for S. maritimus. Overall, the trapping capacity of microplastics in the sediment and on the canopy was higher for subtidal than for intertidal vegetated habitats. We conclude that generalizations in the trapping effect of coastal vegetated areas should be done with caution, since it may be highly variable and may depend on the plastic size, habitat and tidal position. Since these habitats support a high biodiversity, they should be included in assessments of plastic debris accumulation and impacts in coastal areas. Further research, including experimental studies, is needed to shed more light on the role of coastal vegetated habitats as plastic sinks. Unlabelled Image • Macro and microplastic trapping assessment in multiple coastal vegetated habitats • Variability in macro and microplastics density within each habitat was high. • Macroplastics occurred in vegetated habitats but did not in nearby unvegetated ones. • Vegetated and unvegetated habitats had same microplastic abundance in sediments. • Fibres were detected in the canopies of all vegetated habitats except for saltmarsh. [ABSTRACT FROM AUTHOR]

Dissolved oxygen (DO) is considered one of the most important environmental variables of water quality. This work aimed to provide, for the first time, insights regarding DO dynamics on a representative site of the productive Ria Formosa coastal lagoon, south Europe, using a real time monitoring station observatory (acquiring data every 15 min) deployed for a period of two and a half years. This comprehensive data set represents an added value contributing to a better understanding of the DO variability throughout analyzing semidiurnal, daily, fortnightly tidal cycles (spring tide vs. neap tide), seasonal and interannual periods. This observational station was able to capture distinct temporal signatures, including episodic upwelling and meteorological events advancing the knowledge about the functioning of Ria Formosa. DO was highly variable presenting an evident seasonal distribution with the maximum concentration in spring and the minimum in summer night periods. Critical values <5 mg/L were recorded only in 3% of the global data set with negligible hypoxia events, showing infrequent DO stressful conditions in the study area. In addition, the disclosure of its diel dynamics over long periods, provided by this data set, allows to determine the impact of biological activity upon the DO variability and related ecosystem metabolism behavior (autotrophic vs. heterotrophic), through the metric estimation of Net Ecosystem Metabolism (NEM). NEM in the study area revealed to be slightly heterotrophic along one year of observation, reflecting the median percentage of DO saturation (93%). The acquired data set is highly valuable and can contribute to Ria Formosa management and protection, which is imperative for building knowledge-based societies. • A real-time data acquisition observatory station was deployed in Ria Formosa. • Oxygen dynamics in Ria Formosa was highly variable at different temporal scales. • Wider range of DO variability during the summer months under neap tidal conditions • Lower DO concentrations during dawn and during some periods of upwelling events • NEM was slightly heterotrophic at the observatory station. [ABSTRACT FROM AUTHOR]

We investigated the nutrient acquisition of the seagrass Cymodocea nodosa and the importance of sediment to water column nutrient pulses, which regularly occur in coastal lagoons forced by incoming flood tides. Ammonium was preferentially taken up and accounted for 60–90% of the total daily N acquisition, whereas amino acid acquisition through belowground plant parts represented the second most important source of N, accounting 8–34%. The uptake of ammonium pulses increased dramatically the daily N acquisition from 9.5 mmol m−2 day−1 to 1.33 mmol m−2 day−1 at ambient nutrient concentrations, enabling the species to meet its N demand. Roots accounted for 96% of the total phosphate acquisition, with no evidence for P limitation. The ability of seagrasses to adapt to nutrient pulses may be an overlooked nutrition strategy common to many ecosystems where nutrient availability in the water column is low but nutrient pulses occur. • Ammonium is the preferential nitrogen source for the seagrass Cymodocea nodosa. • Amino acid acquisition is the second most important nitrogen source for the species. • Ammonium and phosphate are taken up mostly through the roots. • Leaf uptake becomes dominant under pulsed availability of ammonium and phosphate. • Pulses of ammonium are crucial to meet to sustain the species growth. [ABSTRACT FROM AUTHOR]

A model based on the Dynamic Energy Budget (DEB), was setup to simulate the growth of the Pacific oyster Crassostrea gigas at three different intertidal farming sites, located in Ria Formosa (South Portugal). Locations differed in terms of environmental conditions and culture configurations, namely in density and distance from the bottom. The aim was to test the model capacity for bivalve growth prediction under contrasting environmental conditions and to provide understanding on the main processes driving the growth limitation at those sites (temperature, tide, food quantity and quality factors). The model implementation used, as much as possible, field measurements obtained at each specific site and model results on bivalve growth were compared with in situ growth data. Water level information at each site was extracted from a hydrodynamic model simulation of the entire Ria Formosa. Results showed that all the drivers are significantly important and confirmed that the effect of high inorganic particles concentration in the environment can be as important as the effect of immersion time on the organisms growth. The model performance was satisfactory in reproducing the growth dynamics in both shell length and biomass at each of the three study locations and in different culture configurations without site specific calibration. The model is thus considered to be generic enough to be used in a fully coupled setup with an ecosystem model (MOHID Water Modelling System) in different ecosystems, locations, conditions, and aquaculture configurations, providing a powerful tool to sustainably optimize aquaculture practices. • Temperature, tide, food quantity and quality are equally important for oyster growth. • High inorganic particles concentration is as important as the effect of immersion time. • Model provided good growth dynamics results at three different locations without specific calibration. • Model is generic enough to be used coupled to an ecosystem model for growth prediction. [ABSTRACT FROM AUTHOR]

• Comprehensive tracking of wetland reclamation in Ria Formosa since 1885 as a result of economic activities growth and downfall. • Nearly 2000 ha of coastal wetlands were reclaimed since 1885 in Ria Formosa. • The creation of the Ria Formosa Natural Park in 1987 proved effective in stalling wetland reclamation. • An Ecosystem Approach to Aquaculture could benefit both the conservation and socio-economic values in fragile systems such as coastal wetlands. Economic activities in coastal wetlands are often perceived as incompatible with nature conservation. This negative perception stems from the visible impacts resulting from a continuous process of coastal wetland reclamation, as human pressure increases significantly in global coastal areas. The largest coastal wetland area in southern Portugal, the Ria Formosa, shares a similar perception, where current nature protection status often conflicts with the needed economic development. Here we explore how the economic activities influenced the wetland reclamation process in Ria Formosa, addressing namely aquaculture identified as an activity with a significant compatibilization potential. Different datasets were merged in a Geographical Information System, tracking land use change in Ria Formosa wetlands over the last 130 years at decadal intervals. Our results show that since the end of the 19th century nearly 2000 ha of wetlands were converted to anthropic environments, resulting in a 20 % natural area reduction. From 1885 until the mid-20th century, land use policy was influenced by the significant regional seafood preservation industry, with large swaths of wetlands diked, drained and excavated to give place to traditional salt farms. The following economic downturn gave place for the late industrialization of salt farms, further increasing the reclaimed wetland areas, later stalling with the recognition of the environmental importance of Ria Formosa in 1978. Aquaculture only gained momentum in 1980's with the support of European funding, resulting in the conversion of many unproductive diked areas. However, late 20th century and current land use policy shifted to a nature conservation focus, therefore limiting the use of previously reclaimed areas, a challenge that influenced the abandonment of the modified areas. By studying the long-term change of land use in Ria Formosa, we argue that in high conservation value areas new policies should be considered that stimulate the development of an ecosystem approach to economic activities, namely aquaculture, improving simultaneously the regional environmental status and socioeconomic sustainable development. [ABSTRACT FROM AUTHOR]

Metal history in a natural system was described since the early Holocene by analysing the preserved subsurface sediment record and present-day surface sediments. Normalized geochemical data from six sediment cores (129 samples) was compared with 28 surface samples. Pre-anthropic sedimentary environments allowed the definition of local natural Background Values. Enrichment Factors were then used for elements discrimination in terms of natural and anthropogenic inputs to the system. While subsurface results displayed a similar behaviour in all cores, pointing to largely undisturbed system, surface sediments show significant contamination, with high enrichment factors for As, Cu, Pb, and Zn. Other metal pollutants have generally low enrichment values, suggesting natural conditions. Surface results were reproduced as metal enrichment maps which evidenced anthropogenic sources in specific locations. This work reveals the importance of combining subsurface and surface geochemical data with mapping techniques in order to better evaluate the environmental quality of a natural system. • First description of metal concentration evolution in Ria Formosa during the Holocene • A local natural Background value is determined for seven potential metal contaminants • Although considered largely unpolluted, the Ria Formosa central section presents a significant present-day metal enrichment • Enrichment Factor calculation using local natural Background values greatly improves environmental quality assessment [ABSTRACT FROM AUTHOR]