Castro Marim Research Articles

Development of a Simple Methodology Using Meteorological Data to Evaluate Concentrating Solar Power Production Capacity

Evaluation of the Concentrating Solar Power capacity factor is critical to support decision making on possible regional energy investments. For such evaluations, the System Advisor Model is used to perform capacity factor assessments. Among the required data, information concerning direct normal irradiance is fundamental. In this context, the Engerer model is used to estimate direct normal irradiance hourly values out of global horizontal irradiance ground measurements and other observed meteorological variables. Model parameters were calibrated for direct normal irradiance measurements in Évora (Southern Portugal), being then applied to a network of 90 stations, part of the Portuguese Meteorological Service. From the modelled direct normal irradiance, and for stations that comprise 20 years of data, typical meteorological years were determined. Finally, to identify locations of interest for possible installations of Concentrating Solar Power systems, annual direct normal irradiance availabilities and the respective capacity factor, for a predefined power plant using the System Advisor Model, were produced. Results show annual direct normal irradiance availabilities and capacity factors of up to ~2310 kWh/m2 and ~36.2% in Castro Marim and in Faro, respectively. Moreover, this study supports energy policies that would promote Concentrating Solar Power investments in Southern Portugal (Alentejo and Algarve regions) and eastern centre Portugal (Beira Interior region), which have capacity factors above 30%.

La metalurgia de influencia fenicia en el centro de Portugal. Tres puntas de flecha de arpón lateral de Monte Fiegueiró (Ansião)

This paper presents the results of a study carried out on three previously unpublished Iron Age socketed arrowheads with spur from Monte Figueiró –Central Portugal–, a site located between the Tagus and Mondego rivers. This region is of the utmost importance to understanding how Mediterranean influences penetrated along the Iberian Atlantic coast and up to the inland Portuguese territories, through Phoenician traders, since the Early Iron Age –8th century bc–. The socketed arrowheads with spurs, originally produced in the South-eastern end of Europe, namely in the Black Sea area, are virtually unseen in the Portuguese territory, where only another similar item has been found at Castro Marim –South Portugal–, in contrast with Spain, more specifically with the Guadalquivir region, where they are quite frequently found. Therefore, the occurrence of the three socketed arrowheads from Monte Figueiró is a challenging discovery, since Central Portugal is a peripheral area with respect to the Iberian regions that underwent an actual Phoenician colonisation. Based on this assumption, this paper will not focus just on typological and technological issues, but it will go a bit further, also reflecting on what these three artefacts can reveal about the interaction between indigenous inland communities from Central Portugal and Phoenician traders.

ANÁLISIS COMPARATIVO ENTRE SALINAS SOLARES TRADICIONALES Y OTRAS ACTIVIDADES ECONÓMICAS EN UN ESTUARIO PROTEGIDO PORTUGUÉS

This study shows that Traditional Solar Saltworks can be competitive with other land uses in the Nature Reserve of Castro Marim and Vila Real de Santo Antonio Saltmarshes (“Reserva Natural do Sapal de Castro Marim e Vila Real de Santo António”, in Portuguese), sited in the estuary of the Guadiana River (SW Iberian Peninsula, Europe); particularly, if they are specialized in extraction of Fleur de Sel (or Flower of Salt), a gourmet variety of sea salt. Artisanal sea salt production based on solar evaporationmethods of millennial history in the area is an environmentally sustainable activity in harmony withsaltmarsh landscape. Two crystallizers of a 1 ha Traditional Solar Saltworks were monitored during 70 days from June to August 2015 with the purpose of gathering detailed production data. Monitoring comprised weighing of daily Fleur de Sel harvest while coarse salt survey in one crystallizer, implied packing and weighing after two months. The competitiveness of this new commercialized variety ofsea salt was assessed with respect to other ongoing economic activities in the area, such as aquaculture,industrial salt production, and tourism. Comparison focused on the relationship between the occupied surface and production´s revenue. Water consumption was used as an economic and environmental sustainability indicator. Data were obtained through in-situ monitoring, literature review and from official statistics and spatial data sources. The results indicate that Fleur de Sel extraction in Traditional Solar Saltworks can be a high profile land use form in the area of Nature Reserve, which on a long-term basisis a sustainable activity from a socio-economic and environmental point of view.

Evaluation of mercury methylation and methylmercury demethylation rates in vegetated and non-vegetated saltmarsh sediments from two Portuguese estuaries

Neurotoxic methylmercury (MMHg) is formed from inorganic divalent mercury (Hg2+). However, it is poorly understood to what extent different mercury (Hg) pools contribute to existent MMHg levels. In this study, ambient concentrations of total Hg (THg) and MMHg as well as rates of methylation and demethylation were measured simultaneously in sediments with and without salt-marsh plant vegetation, which were collected in Guadiana and Tagus estuaries, Portugal. Concurrent processes of Hg methylation and MMHg demethylation were directly monitored and compared by spiking sediments cores with stable isotope tracers of 199Hg2+ and CH3201Hg+ followed by gas chromatographic separation and isotope-specific detection using inductively coupled plasma mass spectrometry. Compared to the Guadiana estuary, where concentrations were comparatively low, THg and MMHg levels varied between vegetated and non-vegetated sediments collected at the Rosário site (ROS) of the Tagus estuary. Methylation (KM) and demethylation rates (KD) were also different between estuaries being dependent on the presence of vegetation. In addition, the type of macrophyte species influenced KM and KD values. In fact, the highest KM value was found in Sarcocornia fruticosa vegetated sediments at the Castro Marim site in Guadiana (CM, 0.160 day−1) and the lowest KM was observed in non-vegetated sediments at the Alcochete site in Tagus (ALC, 0.009 day−1). KD varied by a factor of three among sites with highest rates of demethylation observed in non-vegetated sediments in Guadiana (12 ± 1.3 day−1, corresponding to a half-life of 1.4 ± 0.2 h). This study clearly shows that the presence of vegetation in sediments favors the formation of MMHg. Moreover, this effect might be site specific and further studies are needed to confirm the findings reported here.

Characterization of phenolic compounds from different species of halophytes from Reserva Natural do Sapal de Castro Marim e Vila Real de Santo António (Portugal)

Characterization of phenolic compounds from different species of halophytes from Reserva Natural do Sapal de Castro Marim e Vila Real de Santo António (Portugal)

Decomposition and nutrient release in halophytes of a Mediterranean salt marsh

This study dealt with the decomposition and nutrient release from the halophytes Atriplex portulacoides, Arthrocnemum macrostachyum, Limoniastrum monopetalum, and Spartina densiflora, the dominant species in the Castro Marim salt marsh, Portugal. Environmental effects on decomposition were also assessed. The study was carried out for one year using the in situ litterbag technique. S. densiflora showed a lower decomposition rate ( k = 0.003 day −1) than the other study species ( k = 0.005–0.009). Study species showed similar decomposition patterns, that is, the weight loss mostly occurred during the autumn–winter period (study beginning in November). This indicates that temperature in this period did not hamper the decomposition process. The decomposition rate was positively affected by the initial N concentration ( r 2 = 0.87, P < 0.05) and negatively by the C:N ratio ( r 2 = 0.86, P < 0.05) in decomposing materials. At the end of the study, S. densiflora and L. monopetalum, the species with lower initial N concentrations, retained much higher proportion of initial N (89–109%) than the others (5–14%). Also, S. densiflora with the lowest P concentration retained higher proportion of initial P (48%) than the others (5–20%). Release of K and Mg were also slower from S. densiflora and was associated with their initial low concentration in this species. The lowest Mn release was observed from A. macrostachyum and also in relation to the lowest initial concentration. Our study supports the hypothesis that decomposition patterns of marsh species are mostly associated with differences regarding their morphology and chemical composition. Given the higher resistance of S. densiflora to decomposition, its progressive spreading may result in accumulation of organic detritus overtime in invaded salt marshes.

Quantification and potential aroma contribution of β‐ionone in marine salt

AbstractA methodology for quantification of β‐ionone in marine salt was developed using the headspace solid phase microextraction and gas chromatography–quadrupole mass spectrometry (HS–SPME/GC–qMS). Quantification of β‐ionone was achieved by linear regression from an analytical plot of pure standard using the target ion at m/z 177 by ion extraction chromatography (IEC). HS–SPME/GC–qMS combined with IEC mode allowed quantification of trace levels (ng/l) of β‐ionone in marine salt aqueous solutions. The methodology developed presented a good linearity (R2 = 0.981) for the range of concentrations used (16 a 568 ng/l) and a good reproducibility (15%), with limits of detection and quantification of 9 and 29 ng/l, respectively. This methodology was applied to marine salt from different geographical origins (Portugal, France, and Cape Verde). Estimated concentrations of β‐ionone in marine salt varied from 241 to 888 ng/kg of salt. The highest values were found for Aveiro, in Portugal, and Guérande, in France, in environments surrounded by a large number of plant and algae diversity. However, in Castro Marim and Tavira (in Algarve, South of Portugal), this compound was not found. According to the odour threshold of β‐ionone in water (30 ng/l), aqueous solutions with more than 100 g/l of marine salt can exhibit a violet odour. Similar conditions can occur in the ponds with higher levels of salinity of the traditional saltpans. This methodology proved to be a useful tool for screening and quantification of β‐ionone, a compound shown to present potential contribution to marine salt aroma. Copyright © 2010 John Wiley &amp; Sons, Ltd.

The Palaeo-Environmental Contexts of Three Possible Phoenician Anchorages in Portugal

The 2002 Joint Expedition of the Institute of Nautical Archaeology and the Centro Nacional de Arqueologia Nautica e Subaquatica examined Phoenician maritime involvement in Portugal, combining archaeological, geological and geophysical surveys of former coastal sites—Santa Olaia, Abul and Castro Marim—where previous excavations have uncovered Phoenician remains. Significant geomorphic evolution of bay-head delta and estuarine settings masks the fact that Phoenician sites were situated at the head of marine embayments or on estuary margins, had easy access to the sea, and immediate access to at least one natural anchorage. All sites exhibited topographical criteria familiar from Phoenician trading-stations and merchant outposts in the Mediterranean. © 2009 The Authors

Evidence for preferential depths of metal retention in roots of salt marsh plants

Depth variation (2-cm resolution) of Fe, Mn, Zn, Cr, Ni, Cu, As and Cd concentrations were determined in belowground biomass of Spartina maritima and Sarcocornia fruticosa and in sediments between roots from two marshes in Tagus (Rosário) and Guadiana (Castro Marim) estuaries in Portugal with different anthropogenic pressures. Levels of metals were also determined in aboveground plant parts. Metal concentrations in belowground material were 2–4 orders of magnitude greater than levels in aboveground plant parts providing evidence of weak upward translocation. Although both studied species showed poor extraction of Cr and Ni from sediments, S. fruticosa exhibited a large capability to remove Zn, Cu, As and Cd from contaminated sediments and stabilised them in belowground biomass. Accumulated metals showed a sub-surface concentration maximum or increase to basal roots. To evaluate whether these preferential layers of accumulation resulted from availability in sediments or controlled by plant activity, Enrichment Factors (EF = [Me] root/[Metal] sediment) were calculated for each sediment layer. Maximum values in Rosário plant species (Zn = 9.3, Cu = 18, As = 20, Cd = 46) exceeded those obtained in Castro Marim (Zn = 1.3, Cu = 4.3, As = 6.1, Cd = 18). Moreover, EFs varied with the depth indicating the presence of preferential layers of metal accumulation in roots of both plants, but depth zonation was not the same as in the sediments. These results suggested that levels in belowground biomass either integrated in time changes that occurred in solid sediments and pore water, or metal uptake by roots was not proportional to levels in sediments. The same sequence of metals transferred from sediment to belowground biomass for the two plants was obtained for the two marshes (Cd > As > Cu, Zn), although metals differed from mining ore to industrial/urban sources.

Gas exchange in the salt marsh species Atriplex portulacoides L. and Limoniastrum monopetalum L. in Southern Portugal

Salt marshes are ecosystems subjected to a variety of environmental stresses like high salinity, water deficit, intense radiation or high temperatures. Field measurements were conduced in two halophyte species, Atriplex portulacoides L. and Limoniastrum monopetalum L., in the Reserva Natural do Sapal de Castro Marim, to compare their physiological response, i.e., water potential (ψ), net photosynthetic rate (A), stomatal conductance (gs) under natural conditions. Both species demonstrated marked variations in ψ throughout the year, with very low values in the summer, the period of higher salinity, drought and temperature. Deficit water potential (Δψ = ψmidday − ψpredawn) was lower in the summer than in other seasons in A. portulacoides but not in L. monopetalum. The highest values for A and gs in L. monopetalum were observed in autumn and for A. portulacoides in winter, presenting both lowest values in spring and summer. Amax was particularly high for L. monopetalum than for A. portulacoides in summer and autumn, despite gsmax was similar in both species. Diurnal pattern of A and gs were similar in both species, with higher values in the morning, decreasing throughout the day.

The issue of outwelling in the Guadiana River estuary (Portugal): some findings and research suggestions in the context of recent evidence

The “Outwelling Theory” states that salt marshes play a major role in exporting production to adjacent estuarine and coastal ecosystems. However, it has been found that some marshes act as net importers instead of net exporters of organic matter and nutrients. Once we include mangroves and refine the analysis to comprehend bacterioplankton, organic and stable isotope tracers, the picture became, more complex, making room for a revival of the outwelling idea. The exchanges between the Castro Marim salt marsh and the main estuary were tentatively established determining periodically, in a selected cross-section, the concentrations of TSS, FSS, VSS, NH4, NO2, NO3, NKjeldhal, SiO4, PO4, TDP, Chlorophyll a and Pheopigments, measuring their fluxes along tidal cycles and computing the corresponding budgets. Apparently, the sedimentary behaviour of the marsh will be close to equilibrium during the period of study. However, it will import mainly inert matter and export mainly organic matter in the same period. Moreover, extrapolating these results to the entire Guadiana salt marshes, the exchanges of sediment do not seem to be significant. Particularly, the marshes will not trap a significantly amount sediment transported by the main river (0.5%). It also seems to follow, that in a general way, the Guadiana salt marshes might have a more significant role than was anticipated in the system economy of OM and nutrients and their outwelling to coastal waters, assuring outputs that could amount to something like 6% of the river load of N, 1.2% of the river load of P, and 20-57% of the river load of TOC, for an average year, and 42% of the river load of N and 35% of the river load of P in a dry year. These findings suggest that a more detailed investigation, over an extended period of time, is certainly worthwhile.

Primary production and nutrient content in two salt marsh species,Atriplex portulacoides L. andLimoniastrum monopetalum L., in Southern Portugal

Seasonal variation patterns of aboveground and belowground biomass, net primary production, and nutrient accumulation were assessed inAtriplex portulacoides L. andLimoniastrum monopetalum (L.) Boiss. in Castro Marim salt marsh, Portugal. Sampling was conducted for five periods during 2001–2002 (autumn, winter, spring, summer, and autumn). This study indicates that both species have a clear seasonal variation pattern for both aboveground and belowground biomass. Mean live biomass was 2516 g m−2 yr−1 forL. monopetalum and 598 g m−2 yr−1 forA. portulacoides. Peak living biomass, in spring for both species, was three times greater in the former, 3502 g m−2 yr−1, than in the latter, 1077 g m−2 yr−1. For both the Smalley (Groenendijk 1984) and Weigert and Evans (1964) methods, productivity ofL. monopetalum (2917 and 3635 g m−2 yr−1, respectively) was greater than that ofA. portulacoides (1002 and 1615 g m−2 yr−1, respectively). Belowground biomass ofL. monopetalum was 1.7 times greater than that ofA. portulacoides. In spite of this, the root:shoot ratio forA. monopetalum to aerial components. Leaf area index was similar for both species, but specific leaf area ofA. portulacoides was twice that ofL. monopetalum. The greatest nutrient contents were found in leaves. Leaf nitrogen content was maximum in summer for both species (14.6 mg g−1 forA. portulacoides and 15.5 mg g−1 forL. monopetalum). Leaf phosphorus concentration was minimum in summer (1.1 mg g−1 inA. portulacoides and 1.2 mg g−1 inL. monopetalum). Leaf potassium contents inA. portulacoides were around three times greater than inL. monopetalum. Leaf calcium contents inL. monopetalum were three times greater than inA. portulacoides. There was a pronounced seasonal variation of calcium content in the former, while in the latter no clear variation was registered. Both species exhibited a decrease in magnesium leaf contents in the summer period. Mangamese content inL. monopetalum leaves was tenfold that inA. portulacoides. Seasonal patterns of nutrient contents inA. portulacoides andL. monopetalum suggest that availability of these elements was not a limiting factor to biomass production.

Structure and temporal variations of fish assemblages of the Castro Marim salt marsh, southern Portugal

We studied the ichthyofauna of the Castro Marim salt marsh based on monthly sampling surveys at five sites between September 2000 and August 2001. Sampling took place at night during rising neap tides using a 40-m long beach seine. We sampled a total of 7955 fish specimens (37 995.7 g), comprising 34 species and 17 families. The occurrence of most species was occasional, with Pomatoschistus microps (51.9%) and Atherina spp. (10.3%) being the most abundant species, accounting for 62.2% of the total fish captured. Biomass was dominated by the marine species Liza ramado (15.9%), Mullus surmuletus (13.5%), and Liza aurata (13.4%). Temperature and salinity showed a seasonal pattern, with minimums during the winter months and maximums during the summer months. In contrast, river flow peaked in winter and was lowest during summer. This pattern in river flow appears to be correlated with variations in the fish assemblages, which present two distinct compositions during the two periods. A few species characterise the winter fish assemblage, with dominance by residents and the presence of freshwater species, while the summer assemblage is characterised by the presence of many marine visitors that use the salt marsh in their first months/years of life. Temporal variations in total abundance and biomass reflect fluctuations in the dominant species. Resident species presented the highest abundance values, while marine adventitious species and marine species that use the salt marsh as a nursery ground contributed most to community species richness. Castro Marim salt marsh constitutes an important ecosystem for fishes, providing habitat for many species, especially juveniles, which find conditions within the salt marsh suitable for their development.

Feeding ecology and trophic relationships of fish species in the lower Guadiana River Estuary and Castro Marim e Vila Real de Santo António Salt Marsh

In this study we analyze the feeding ecology and trophic relationships of some of the main fish species (Soleidae, Moronidae, Mullidae, Sparidae, Mugilidae, and Batrachoididae) of the lower Estuary of the Guadiana River and the Castro Marim e Vila Real de Santo António Salt Marsh. We examined the stomachs of 1415 fish caught monthly between September 2000 and August 2001. Feeding indices and coefficients were determined and used along with the results of multivariate analysis to develop diagrams of trophic interactions (food webs). Results show that these species are largely opportunistic predators. The most important prey items are amphipods, gobies (Gobiidae), shrimps ( Palaemon serratus and Crangon crangon), and polychaete worms. The lower Estuary and associated salt marshes are important nurseries and feeding grounds for the species studied. In this area, it is therefore important to monitor the effects of changes in river runoff, nutrient input, and temperature that result from construction of the Alqueva Dam upstream.

Dispersal of invasive and native brine shrimps Artemia (Anostraca) via waterbirds

North American brine shrimp Artemia franciscana have been exported worldwide since the 1950s for use in aquarium trade and fish farming. Aquaculture is expanding along the Mediterranean coast, leading to the release of A. franciscana into native Artemia populations. A. franciscana was first detected in 1981 in Portugal and has since spread to saltworks along the East Atlantic flyway used by shorebirds. Once A. franciscana becomes established in a locality, native Artemia tend to disappear. To test whether migratory shorebirds can disperse invasive and native Artemia between wetlands, we extracted Artemia cysts from feces and pellets collected at Castro Marim (Portugal) and Cadiz Bay (Spain) during southward migration. We found that large numbers of viable eggs of A. franciscana and native Artemia partheno-genetica were dispersed by Redshank Tringa totanus, Blacktailed Godwit Limosa limosa, and other shorebirds migrating through the Iberian Peninsula. This is the most extensive field demonstration to date that invertebrates can disperse readily via gut passage through birds.