Solar Saltworks Research Articles

Biochemical composition and digestive enzyme activity during naupliar development of Artemia spp from three solar saltworks in Greece

Three parthenogenetic brine shrimp Artemia populations from saltworks in Greece (Messolongi, Milos and Polychnitos) were studied with regard to their biochemical composition and the activity of digestive enzymes in four developmental stages from decapsulated cysts to nauplii instar III. The content of protein and RΝΑ was highest in nauplii instar II (65.10 and 6.23% dry weight, respectively), while that of total lipid was highest in nauplii instar I (11.40% dw). The carbohydrate content was highest in decapsulated cysts (10.30% dw) and about one half that value in nauplii instar I. The DNA content was ten-fold higher in nauplii instar I than in decapsulated cysts with the highest levels in nauplii instar III (3.67% dw). The activity of alkaline phosphatase, leucine aminopeptidase, valine aminopeptidase, cystine aminopeptidase, β-galactosidase, β-glucosidase, esterase lipase (C8), esterase (C4), N-acetyl-β-glucosaminidase, α-fucosidase, acid phosphatase and naphthol-AS-BI-phosphohydrolase increased significantly from decapsulated cysts to nauplii instar II and remained constant or decreased in nauplii instar III. In nauplii instar II, leucine aminopeptidase, β-galactosidase, alkaline phosphatase and esterase (C4) demonstrated higher activity levels (140.90, 133.62, 66.01 and 45.47 nmoles/100 µg dw within 5 min, respectively) of the aforementioned enzymes. The Artemia population of Messolongi had significantly higher levels of DNA, protein and alkaline phosphatase activity per individual, as well as body weight, compared to the Artemia populations of Milos and Polychnitos. The latter population showed the lowest level of lipid and the highest esterase activity (C4) per individual. There was a reverse relationship between the protein content and leucine aminopeptidase activity, lipid content and esterase (C4) activity, carbohydrate content and β-galactosidase activity among the three Artemia populations. The variations observed in the biochemical composition and the activity of some specific enzymes should be taken into consideration in selecting these Artemia populations from Greece for application in aquaculture.

A SOLAR POWERED LIQUID-DESICCANT COOLING SYSTEM FOR GREENHOUSES

Liquid desiccant systems are of potential interest as a means of cooling greenhouses to temperatures below those achieved by conventional means. However, only very little work has been done on this technology with previous workers focussing on the cooling of human dwellings using expensive desiccants such as lithium salts. In this study we are designing a system for greenhouse cooling based on magnesium chloride desiccant which is an abundant and non-toxic substance. Magnesium chloride is found in seawater, for example, and is a by-product from solar salt works. We have carried out a detailed experimental study of the relevant properties of magnesium rich solutions. In addition we have constructed a test rig that includes the main components of the cooling system, namely a dehumidifier and solar regenerator. The dehumidifier is a cross-flow device that consists of a structured packing made of corrugated cellulose paper sheets with different flute angles and embedded cooling tubes. The regenerator is of the open type with insulated backing and fabric covering to spread the flow of desiccant solution. Alongside these experiments we are developing a mathematical model in gPROMS® that combines and simulates the heat and mass transfer processes in these components. The model can be applied to various geographical locations. Here we report predictions for Havana (Cuba) and Manila (Philippines), where we find that average wet-bulb temperatures can be lowered by 2.2 and 3°C, respectively, during the month of May.

Spatial and seasonal variability of the macrobenthic fauna in Mediterranean solar saltworks ecosystems

1. Solar saltworks are man-made systems for the production of salt and are characterized by high habitat heterogeneity owing to the existence of a strong salinity/confinement gradient. Although solar saltworks are considered to be artificial systems, they are also coastal aquatic ecosystems sharing common characteristics with natural transitional waters ecosystems, which are of special interest to the Water Framework Directive (2000/60/ EC). 2. Spatial and seasonal distribution of macrobenthic invertebrates in relation to the abiotic environment of two Mediterranean solar saltworks ecosystems were assessed in this study. The spatial distribution investigated in this study ranged from the regional scale (Kalloni Saltworks, NE Aegean and Margherita di Savoia Saltworks, S. Adriatic) down to a local scale of 100s of metres in each ecosystem. 3. The macrobenthic community was variable at most spatial and seasonal scales examined in this study: spatial variability at the regional level was greater than seasonal variability within ecosystems and spatial variability among the salinity/confinement gradient levels was greater than within-level variability. 4. The abiotic environment, in both its spatial and seasonal aspects, was found to be crucial in determining the macrobenthic community structure. Biotic factors such as the life cycle of key species, the inter-specific competition as well as dispersion/colonization/extinction processes were also found to play an important role in structuring the macrobenthic fauna both in space and time. 5. A strong similarity of the macroinvertebrate faunal composition and community structure of the lower salinity ponds of solar saltworks with that of natural transitional waters ecosystems was observed. Therefore, solar saltworks ecosystems can be considered as important sites of study for the purposes of the Water Framework Directive.

Seasonal community structure of the molluscan macrofauna at the marine‐lagoonal environmental transition at Kalloni solar saltworks (Lesvos Island, NE Aegean Sea, Greece)

Solar saltworks are extremely heterogeneous coastal aquatic ecosystems whose benthic biodiversity patterns have not been comprehensively investigated yet. The present study focuses on the seasonal community structure of the macrobenthic molluscs at the marine‐lagoonal environmental transition that takes place at Kalloni solar saltworks (Lesvos Island, NE Aegean Sea, Greece). The molluscan community was studied by means of four seasonal collections carried out in 2004 at four sites in the study area. The molluscan community was found to be considerably species‐rich and forming a coenocline, as marine species were gradually replaced by lagoonal species with increasing distance from the sea. The major variable in the implied environmental gradient structuring the molluscan community appeared to be confinement rather than salinity, although zonation of the molluscan community structure was rather broad. The pattern of spatial organization of the molluscan fauna did not appear to change seasonally, although seasonal shifts of the zones did occur in the study area.

Microbial communities in Messinian evaporite deposits of the Vena del Gesso (northern Apennines, Italy)

The Vena del Gesso (Northern Apennines) is a 230 m-thick succession consisting of up to 16 gypsum-shale cycles belonging to the “Lower Evaporites” formed during the Messinian salinity crisis in theMediterranean. The study of the microbial communities preserved in the gypsum crystals of one complete cycle (6 th cycle at Monte Tondo quarry) showed abundant, regularly arranged filamentous forms that resemblemorphologically modern obligate phototrophes, cyanobacteria colonizing modern photic, shallow-water gypsum basins. At least four different bacterial populations have been recognized: a) filamentous type cyanobacteria with characteristic inserted funnel shaped structure resembling the modern Scytonematacean; b) Type 1 organisms consisting of filamentous structures impregnated by clay minerals containing pyrite grains in the outer sheath; c) Type 2 filaments filled by clay minerals with dolomite in the outer sheath; d) Type 3 filamentous organisms with a central hollow tube and an encrusted outer sheath mainly composed of calcium carbonate. These organisms were probably associated with other heterotrophic bacteria as suggested by the presence of dolomite and pyrite structures. The size and preservation suggest that most of these cyanobacteria were likely conducting oxygenic photosynthesis as presently observed in modern solar salt works. It follows that they were living in shallow water settings or settled down from the water column to the bottom of a relatively deep evaporite basin.

Physiological characterization of Dunaliella sp. (Chlorophyta, Volvocales) from Yucatan, Mexico

Physiological responses of Dunaliella salina and Dunaliella viridis, isolated from solar saltworks on the Yucatan Peninsula, were studied. Optimal growth temperature for D. salina was 22 °C (3.06 × 10 6 cells mL −1) and 26 °C for D. viridis (4.04 × 10 6 cells mL −1). Total carotenoid content in D. salina increased with temperature to a maximum of 35.14 pg cell −1 at 38 °C. Dunaliella salina α-carotene and β-carotene content was 0.083 ± 0.003 and 0.598 ± 0.020 mg 100 g dry wt −1 respectively, whereas lower values were found in D. viridis cultured under same experimental conditions (0.018 ± 0.002 and 0.136 ± 0.012 mg 100 g dry wt −1 respectively). The highest specific growth rate in D. salina was obtained at 10% NaCl (0.28 d −1), while its cell volume increased from 524 to 2066.93 μm 3 when cultured from 10% to 35% NaCl. Maximum photosynthetic rates were attained when increasing from optimal growing temperature to 30 °C for D. viridis (108 nmol O 2 μg chl a h −1) and D. salina (139 nmol O 2 μg chl a h −1). Photosynthetic responses to temperature variations indicated physiological adjustments in both species, with higher acclimation in D. salina. Evaluation of physiological attributes of these species will be used for to carry out mass cultivation.

Composition and distribution of planktonic ciliates from ponds of different salinity in the solar saltwork of Sfax, Tunisia

The planktonic ciliated protozoa of 14 ponds of increasing salinity were investigated in the saline of Sfax, Tunisia. Taxa of the classes of Spirotrichea and Heterotrichea were the numerous ciliates. Abundance of the community ranged from 0.0 to 11.8 × 10 4 ciliates per litre. Values decrease significantly with salinity gradient, as species richness does. Based on the range of salinity over which ciliate taxa appeared, we distinguished three groups of ciliates. The first group is mainly composed of oligotrichs and choreotrichs that are commonly found in marine coastal waters. Small ciliates belonging to the order Prostomatida were found in a large range of salinity values, but their densities also decreased with salt concentration. In contrast, large-size species of heterotrichous ciliates were found in ponds with high salinity values only. In these ponds, the presence of prey appeared as an important factor in controlling the abundances of these halotolerant ciliates. Our data also suggest that Fabrea salina, a common halophile ciliate, acts as a competitor of the brine shrimp Artemia salina in the saline of Sfax. Salinity, prey availability, and the presence of competitors seem to be the main factors for the distribution of ciliate taxa in this hypersaline environment.

Abundance and growth response of microalgae at Megalon Embolon solar saltworks in northern Greece: An aquaculture prospect

There is continuous interest in many countries in maintaining and manipulating the rich ecological value of hypersaline ecosystems for aquaculture. The Megalon Embolon solar saltworks (northern Greece) were studied in sites of increasing salinity of 60–144 ppt to evaluate Dunaliella salina abundance and microalgal composition, in relation to physical and chemical parameters. Cluster and ordination analyses were performed based on the biotic and abiotic data matrices. Using fresh aliquots from 60 and 140 ppt salinity waters, phytoplankton performance was appraised with flask cultures in the laboratory by varying the inorganic PO4-P concentration at 23 °C and 30 °C. At the saltworks, among the most abundant microalgae identified were species of the genera Dunaliella, Chlamydomonas, Amphora, Navicula, and Nitzschia. Dunaliella salina populations were predominant comprising 5–22% of the total microalgal assemblages during spring, but only 0.3–1.0% during the summer, when grazing by Artemia parthenogenetica and Fabrea salina was intense. D. salina cell density in April–July was in the range of 0.4–12.5 × 106 L−1 with typical densities of 1.5–4.5 × 106 L−1. Overall, microalgal densities were high in salinities of ≥100 ppt when inorganic-P concentrations were ≥0.20 mg L−1 within saltworks waters. Multivariate analysis of species abundance showed that algal growth responses were primarily related to variation in salinity and inorganic-P concentrations, but also to NO3-N concentration. In the laboratory, experiments indicated effective fertilization and denser microalgal growth under high inorganic PO4-P applications (4.0 and 8.0 mg L−1) at 60 ppt salinity and 23 °C. The lower PO4-P applications (0.6–2.0 mg L−1) were more effective at 60 ppt salinity and 30 °C. At 140 ppt salinity, microalgal growth response was less obvious at any of the corresponding phosphorus concentrations or temperatures. In both salinity experiments, Dunaliella salina bloomed easily and was predominant among the microalgae. Our observations indicate that Dunaliella salina populations and the overall rich microalgal profile of the saltworks, along with their performance in laboratory mono–and mixed cultures hold promise for mass cultivation within the M. Embolon saltworks basins.

Predation by the Western Gull on the Eared Grebe at a Salina in Mexico

We studied the predation of the Western Gull (Larus occidentalis) on the Eared Grebe (Podiceps nigricollis) from December 2002 to June 2003 at a solar saltworks. Mechanisms of predatory behavior, such as use of perching site, attack maneuvers and killing and catching grebes, as well as behavior of the grebes as a response to the presence and attacks by gulls, were recorded. In all 35 cases where a gull attempt to feed was seen, it was successful in every case. This is the first report about predation by the Western Gull on the Eared Grebe.

An analysis of the performance of an artificial wetland for nutrient removal in solar saltworks

A small artificial wetland was constructed through which intake water flowed before entering the initial pond of a solar saltworks. This trial wetland was designed for the removal of excessive nutrients from the water as the system is becoming hypertrophic. Spartina maritima (Curtis) Fernald was the dominant halophytic grass used in the wetland and Ulva rigida C. Agardh the dominant macroalga. The nutrient content of the inflow and outflow water of the wetland was monitored for eight months after construction. For seven out of nine analyses, the ammonium concentrations of water flowing out of the wetland were significantly reduced (by an average of 56%) when compared to those measured in water flowing into the wetland. Nitrate and phosphate concentrations for eight out of nine analyses also showed significant reductions (by 60% and 56% respectively). The success of this wetland indicates that it can be an effective management tool for nutrient reduction in solar saltworks.

Crustacean assemblage and environmental characteristics of a man-made solar saltwork in southern France, with emphasis on anostracan (Branchiopoda) population dynamics

Physical and chemical variables, anostracan populations (Artemia parthenogenetica and Branchinella spinosa) and other biota were studied during 1996–1997 in a Camargue saltern (max. depth ∼1 m). The taxonomic composition and density of macroinvertebrates were investigated twice monthly, based on benthic substrate and water column samples. Fauna was composed of three groups in terms of numerical importance. The benthic macroinvertebrates were represented only by nematodes ( 500 ind. m−2 in November–December and May respectively). The zooplankton was dominated by crustaceans, one cladoceran, Moina salina (ranging from 670 to 2350 ind. m−2 in spring), two anostracans, Artemia parthenogenetica (< 50 ind. m−2 in autumn), and Branchinella spinosa (max. 190 ind. m−2 in December to absent in April), and two copepods, Cletocamptus retrogressus (max. density 2000 ind. m−2 in November), and Eurytemora velox (max. density 650 ind. m−2 in February–March). Insects (Chironomidae, Culicidae) were rare, with mean densities < 1 ind. m−2. The phenology of each crustacean population is discussed in relation to physical and chemical water variables. Salinity appeared to be of greatest importance regulating the population abundance.

Evaluating seawater chemistry from fluid inclusions in halite: examples from modern marine and nonmarine environments

Fluid inclusions from marine halites have long been studied to determine the chemical composition of ancient seawater. Chemical analyses of the major ions in fluid inclusions in halites from the solar saltwork of Great Inagua Island, Bahamas, and from the supratidal sabkha, Baja California, Mexico, show that modern marine halites faithfully record the chemical signature of seawater. The major ions in Great Inagua and Baja California fluid inclusions display distinctive linear trends when plotted against one another (ie., Na+, K+, and SO42− vs. Mg2+ and Cl−), which track the evaporation path of seawater as it evolved during the crystallization of halite. These evaporation paths defined for the major ions by fluid inclusions in halite overlap findings of computer simulations of the evaporation of modern seawater by the Harvie, Møller, and Weare (HMW) computer program. The close match between the HMW seawater evaporation paths and the Great Inagua fluid inclusion data is not surprising considering the carefully controlled inflow, evaporation, and discharge of seawater at the Great Inagua saltwork. The major ion chemistry of fluid inclusions from the Baja California halites matches the HMW seawater evaporation paths in most respects, but one Baja fluid inclusion has lower concentrations of Mg2+ than evaporated seawater. Nonmarine inflows and syndepositional recycling of preexisting salts in the Baja California supratidal setting were not large enough to override the chemical signature of evaporating seawater as the primary control on the Baja fluid inclusion compositions. Fluid inclusions in halites from the nonmarine Qaidam Basin, Qinghai Province, western China, have a distinctly different major ion chemical signature than does “global” seawater. The fluid inclusion chemistries from the Qaidam Basin halites do not lie on the evaporation pathways defined by modern seawater and can clearly be differentiated from fluid inclusions containing evaporated seawater. If fluid inclusions in halites from modern natural settings contain unmistakable samples of evaporated seawater, then evaluation of the chemistry of ancient seawater by chemical analysis of fluid inclusions in ancient marine halites by means of the same approach should be valid.

Study on the Impact of Fertilization on the Production of Artemia (Cyst and Biomass) and Salt in an Integrated System from the Solar Salt Works of Bangladesh

Study on the Impact of Fertilization on the Production of Artemia (Cyst and Biomass) and Salt in an Integrated System from the Solar Salt Works of Bangladesh

Role of Extremophyles in Solar Salt Production

Abstract One-third of the worldwide sodium chloride (salt) production (about 200 million tons per year) is manufactured in solar saltworks. A solar saltworks is a series of one or more interconnected, shallow concentrating ponds (40 to 70 cm deep) through which seawater flows, evaporates by wind and sun, and deposits sodium chloride on the floors of crystallizer ponds (30 cm to 50 cm deep). In the downstream flow, salts of low solubility (in respect to sodium chloride) precipitate, with calcium carbonate first dropping out near three times, and calcium sulfate (gypsum) first appearing near four times seawater salinity. Shortly before reaching saturation with sodium chloride (about S.G. 1.214), the brine flows into crystallizer ponds (crystallizers), where evaporation continues until 5 to 20 cm of sodium chloride is deposited on the floors. The supernatant liquid, rich in compounds of calcium, magnesium, chloride, and sulfate, is removed, and the salt is harvested, washed, stockpiled for a time to decrease contaminants, and marketed.

Caribbean Flamingos Feeding at a New Solar Saltworks in Western Venezuela

-From October 1996 toJune 1998, we determined to what extent Caribbean Flamingos (Phoenicopterus ruber ruber) at the Los Olivitos Wildlife Refuge and Fishing Reserve, western Venezuela, fed at a new, adjoining solar saltworks. Soon after filling (October 1996), 39% of the birds fed at the saltworks (Concentrator 1), but within a month 1,000) until several months later (May 1998). Thus, birds visited the area infrequently but in large numbers. In all, 17.4% of the birds that visited the wildlife refuge fed at the saltworks. Evidently, a large number of feeding birds (2,922) quickly overexploits the food supply, which needs time to recuperate. Also, copepods and amphipods, abundant in the beginning (OctoberNovember 1996), were eliminated due to increasing salinity in the concentrator and replaced with brine shrimp (Artemia sp.) and brine fly larvae (Ephydra sp.) by March-May 1998. In Venezuela, solar saltworks are important for flamingo conservation because they offer alternative and protected feeding sites. At the Los Olivitos saltworks, 68% of the total flamingo population in Venezuela and Bonaire may feed there on any given day. FLAMENCOS ALIMENTANDOSE EN UNA NUEVA SALINA SOLAR EN EL OESTE DE VENEZUELA Resumen.-Desde octubre de 1996 hastajunio de 1998, nosotros determinamos si el flamenco caribefio (Phoenicopterus ruber ruber) que habita el Refugio de Fauna Silvestre Los Olivitos, Cienaga de Los Olivitos, al oeste de Venezuela, utiliza los concentradores de una nueva salina solar comercial adyacente al refugio como Area de alimentaci6n. Poco despues del llenado de los concentradores (octubre de 1996), el 39% de las aves se alimentaban en las instalaciones de la empresa salinera (Concentrador 1), pero al cabo de un mes, 1,000) hasta varios meses mis tarde (Mayo 1998). Asf, las aves visitaron el irea de forma infrecuente pero en gran ndimero. Por todo, 17,4% de las aves que visitaron el refugio se alimentaron en la empresa salinera. Evidentemente, un gran nfimero de flamencos alimentindose (2.922) ripidamente sobreexplot6 el suministro alimenticio que necesita tiempo para recuperarse. Ademis, debido al incremento de la salinidad en el concentrador, cop6podos y anfipodos, abundantes al principio (octubrenoviembre de 1996), fueron eliminados y reemplazados por artemia (Artemia sp.) y la larva de la mosca salina (Ephydra sp.) en los meses de marzo-mayo de 1998. En Venezuela, las empresas salineras son importantes para la conservaci6n del flamenco, porque ellas ofrecen un sitio alternativo y protegido de alimentaci6n. En la empresa salinera de Los Olivitos, 6-8% del total de la poblaci6n de flamencos de Venezuela y Bonaire podria alimentarse alli en cualquier momento.

The salt ooids of Berre salt works (Bouches du Rhône, France): the role of bacteria in salt crystallisation

Abstract Salt ooids that form in the solar salt works of Berre (France) are studied principally through SEM imagery. They are compared to halite particles obtained in the laboratory by bacterial mediation under controlled conditions. Salt crystallisation appears to be induced and oriented by the growth of bacterial colonies. The main bacterial processes involved are the multiplication of cells and the regulation of their internal salt concentration which tends to oversaturate the closely neighbouring environment. Such biogeological processes could have played a significant role in rocksalt deposition over geological times.

Observations on a solar saltworks near Burgas, Bulgaria

Data on biota and nutrients in solar ponds of a saltworks near Burgas, Bulgaria, were obtained. Surveys of the biota were undertaken, and records from management officials gave information on biological and physical conditions related to salt production. The decrease in the quality and quantity of sodium chloride harvested that began 10 to 15 years before the study, may be related to the high levels of plankton, combined nitrogen and phosphate, and the large accretion of bottom sediments and density of benthic communities. Biological management can improve the quality and quantity of the sodium chloride produced by the saltworks.

Variability and adaptations of some halobiotic cyanophytes in solar salt works and under stressing laboratory conditions

Variability and adaptations of some halobiotic cyanophytes in solar salt works and under stressing laboratory conditions

Biological and physical events involved in the origin, effects, and control of organic matter in solar saltworks

Aspects of communities and events in the concentrating ponds (S.G. 1.130 to 1.214) and salt crystallizing ponds (S.G. 1.215 to 1.264) of solar saltworks pertinent to salt manufacture are described. Communities that aid salt manufacture enable continuous and efficient production of high quality salt at a saltworks' design capacity, and they provide important controls on levels of organic matter in the brine. Fluctuating salinities, high concentrations of nutrients, and petroleum products are disturbances that causeAphanothece halophytica andDunaliella salina to release excessive quantities of organic matter, and that suppress or cause death to nutrient stripping organisms. Disturbances result in decreased quality and quantity of salt and increased costs for salt harvest, washing, and pond upkeep. Organic matter can be controlled by management techniques that keep nutrient stripping communities at proper levels and maintain a narrow and unchanging range of salinities in each pond, by constructing pond dikes able to withstand wind and water erosion, and by preventing spills of petroleum products in the ponds.

International study on Artemia XLIX. Salinity effects on survival, maturity, growth, biometrics, reproductive and lifespan characteristics of a bisexual and a parthenogenetic population of Artemia

Two Artemia populations, a bisexual from San Francisco Bay (California, USA) and a parthenogenetic from Tanggu area (Tianjin province, People's Republic of China) are assayed for their tolerance and fitness in various salinity levels. This study was carried out under laboratory conditions where salinity effects upon special characteristics of the two Artemia populations, such as survival, growth rate, maturation, morphology, fecundity and life duration, were recorded. This evaluation revealed that the two populations examined exhibits significant differences in their response against elevated salinity levels. Furthermore, specific biometric parameters can be a useful tool for the discrimination and/or determination of their distribution in a mixed population, which, in fact, is the case in Tanggu salt works. Artemia franciscana seems to be a more effective colonizer at higher salinities. The data presented in this study may generate useful suggestions for proper management of the solar saltworks at Tanggu although further experimentation is needed.