Constant Salinity Research Articles

SEAWAT Scenarios Evaluating Links between the Southern Gabès (TN) Confined Aquifer and the Mediterranean Sea

The southern Gabès aquifer in southeastern Tunisia faces significant stress due to unsustainable groundwater extraction. This study employs a SEAWAT model to evaluate groundwater losses, salinization mechanisms, and the interaction between the confined aquifer and the Mediterranean Sea. The model, incorporating well pumping rates, regional freshwater inflows from the Matmata Mountain Range, and the Mediterranean Sea boundary, demonstrated high accuracy in simulating hydraulic heads. Findings reveal that regional inflow is only half of the current pumping rate, indicating unsustainable groundwater use. The study also assessed salinity dynamics by modeling the Mediterranean Sea as a constant head and salinity boundary. Results suggest limited exchange between the aquifer and the sea, challenging previous assumptions. While the immediate risks of salinization are low, continued over-extraction could compromise the aquifer’s long-term sustainability. This research highlights the need for stricter local groundwater management, offers insights into regional coastal aquifer interactions, and contributes to global discussions on managing stressed aquifer systems.

A novel stepwise salinity acclimation method to improve the survival of freshwater microalgae Haematococcus lacustris in seawater salinity.

Freshwater microalga Haematococcus lacustris rich in astaxanthin, as a supplemental live diet can directly supply natural astaxanthin to the aquaculture organisms, except marine aquaculture organisms, since H. lacustris cannot tolerate seawater salinity. The objective of the present study is to provide a salinity acclimation method that allows H. lacustris to survive and accumulate astaxanthin with the aim of developing a novel supplemental live diet for marine aquaculture organisms. H. lacustris cultured in freshwater was subjected to different stepwise salinity acclimation processes (two-, three-, and four-shift). As the controls, H. lacustris was exposed to five constant salinities conditions (0, 0.05, 0.075, 0.3, and 0.6M NaCl, respectively). Among the controls, almost all cells in the 0.3M and 0.6M NaCl conditions died immediately. In contrast, H. lacustris in the stepwise salinity acclimation processes survived in 0.6M NaCl (equivalent to seawater salinity of 35 psu), showing the highest living-cell proportion (50.0%) and astaxanthin yield (0.72mg·L-1) in the four-shift. The present study first demonstrated that H. lacustris tolerated seawater salinity through a stepwise acclimation process, proving a new strategy to supply live microalgal diets rich in natural astaxanthin for marine aquaculture.

Response of aerobic granular sludge to salinity fluctuations in formation, stability and microbial community structures

Aerobic granular sludge (AGS) exhibits excellent resistance to adverse environment due to its unique layered structure. However, the mechanism about how salinity fluctuations in municipal wastewater impact AGS formation and its physicochemical properties has not been thoroughly revealed. In this study, AGS was cultivated under additional 0 % salinity (R1), additional 1.5 % constant salinity (R2), and additional 0–1.5 % fluctuant salinity (R3), respectively. The results indicate that increased salinity can enhance extracellular polymeric substances (EPS) production and improve sludge settleability, thereby facilitate AGS formation. However, the AGS experienced frequent environmental conversion between dehydration and swell due to salinity fluctuations, resulting in higher content of loosely-bond EPS and low settleability, which delayed the maturation of AGS for over 14 days. Additional salinity significantly inhibited the nitrification process, but the formation of AGS promoted the recovery of ammonia oxidation activity and facilitated the construction of short-range nitrification denitrification processes, resulting in over 16.0 % higher total nitrogen removal efficiency than R1. The microbial community analysis revealed that Thauera played an important role in the granulation process under salinity stress, due to its salt tolerance and EPS secretion abilities. As expected, the formation of AGS enhanced the salt resistance of microorganisms, allowing for the enrichment of functional bacteria, such as Flavobacterium and Candidatus_Competibacter. Generally, microorganisms required extended adaptation periods to cope with salinity fluctuations. Nevertheless, the resulting AGS proved stable and efficient wastewater treatment performance.

Resilience to changes in salinity and predator diversity in representative Gulf of Mexico estuarine fish predator-prey interactions

Predators strongly influence ecological communities and subsequent ecosystem function by directly consuming prey individuals and indirectly by inciting alterations in prey behavior, termed non-consumptive effects (NCEs). Gulf of Mexico estuaries support complex food webs structured by numerous species interactions maintained in constant environmental flux from variation in salinity. Environmental variation presents a source of physiological stress for estuarine fish and plays a role in their distributions and subsequent interactions. Here, we present the results of a mesocosm experiment examining if acute changes in salinity disrupt NCEs of different predators on estuarine prey. We exposed Gulf killifish (Fundulus grandis) to visual and/or olfactory cues from a common estuarine predator, red drum (Sciaenops ocellatus), and from a freshwater predator that is a transient species in lower portions of estuaries, largemouth bass (Micropterus salmoides), under either decreasing, constant, or increasing salinity. Killifish decreased shoal size and movement in response to olfactory cues or both visual and olfactory cues compared to when they were exposed to no cues or visual cues, demonstrating variable perceived risk dependent on cue type. Behavioral response did not vary by predator species, implying a generalized response to different fish predators. Prey did not change behavior when exposed to decreasing salinity compared to constant salinity. However, prey movement increased with increasing salinity, indicating that salinity changes may provide cues to search for different habitats instead of a stressor. Our experiment indicates that estuarine predator-prey interactions may be resilient to acute salinity changes given the broad tolerances of euryhaline species.

Development of surfactant formulation for high-temperature off-shore carbonate reservoirs.

The residual oil left behind after water flooding in petroleum reservoirs can be mobilized by surfactant formulations that yield ultralow interfacial tension (IFT) with oil. However, finding ultralow IFT surfactant formulations is difficult for high-temperature, off-shore, carbonate reservoirs. These reservoirs are often water-flooded with seawater (with a lot of divalent ions), which is often incompatible with many surfactants at high temperatures. The goal of this research is to develop a surfactant formulation for an off-shore carbonate reservoir at 100°C previously flooded by seawater. Surfactant-oil-brine phase behavior was studied for formulations, starting from a single surfactant to mixtures of surfactants and a co-solvent. Mixtures of three surfactants and one co-solvent were needed to produce ultralow IFT formulations for the oil of interest. The surfactant system with polymer mobility control was tested in crushed reservoir rock packs. The cumulative oil recovery was >99% for the surfactant-polymer (SP) flood with an optimal salinity gradient. The constant salinity SP floods with seawater increased oil recovery significantly beyond the water flood (cumulative oil recovery >91%), even though the recovery was lower than that of the optimal salinity gradient SP flood. Our experimental work demonstrates the effectiveness of the surfactant formulation for a high-temperature carbonate reservoir at seawater salinity.

Effects of constant and variable salinity regimes on the occurrence, feeding, and growth of two juvenile flatfishes (Pseudopleuronectes yokohamae and Platichthys bicoloratus)

Extreme environmental conditions, such as high and low salinity, are stressors for marine fish growth. Juveniles of marbled flounder Pseudopleuronectes yokohamae and stone flounder Platichthys bicoloratus use estuaries as nursery grounds. Our field surveys showed that the occurrence of juvenile stone flounder seemed to be unrelated to salinity, whereas that of juvenile marbled flounder was positively correlated with salinity. To examine the effects of salinity on feeding and growth of these species, we conducted a laboratory experiment in which juveniles were reared individually under constant and variable salinity regimes for seven days. Cultured marbled flounder of two sizes (23–29 and 48–58 mm standard length) were reared under constant salinities of 5, 15, and 30 and fluctuating salinities of 5–30 and 15–30 or 5–15. Wild stone flounder (23–37 mm standard length) were reared under constant salinities of 1, 5, and 30 and fluctuating salinities of 5–30 and 1–30. Commercial pellets were fed to fish twice daily until satiation. The feeding and growth of marbled and stone flounders were considerably low at constant salinities of 5 and 1, respectively. Meanwhile, suppression of feeding and growth was not observed in fish with salinities varying from 5 to 30 or 1 to 30, respectively. The results indicated that extremely low salinity inhibits feeding and growth of juveniles only with continuous exposure. Estuaries with fluctuating salinities are potential nursery grounds for both marbled flounder and stone flounder, although marbled flounder tend to avoid low-salinity environments in the field. This study showed that extremely low-salinity environments, which reduce juvenile growth when consistently exposed, would not affect distribution or growth if they were temporary around low tide.

Reproductive conditioning, spawning induction and early development of the estuarine Caribbean clam, Polymesoda arctata (Deshayes, 1854), under hatchery conditions

Polymesoda arctata is a Caribbean estuarine clam commercially important that currently is considered threatened. The reproductive conditioning, spawning and early development were evaluated under laboratory conditions using organisms collected in the lagoon system of Ciénaga Grande de Santa Marta (Colombian Caribbean) between December 2020 and May 2021. Two reproductive conditioning experiments were conducted over 7 weeks, examining the frequency of mature animals in the natural environment (controls) and in the laboratory under two water temperatures (26 and 29 °C) and different salinity regimes (constant at 5 and 15 ppt, increasing from 5 to 15 ppt, and decreasing from 15 to 5 ppt). One spawning experiment was done, comparing the spawning response of adult clams exposed to various stimuli (changes in water temperature and salinity, flow of seawater irradiated with UV light, addition of a high concentration of food and sperm to the water, as well as injections of serotonin and KCl into the foot and/or adductor muscle). Higher frequencies of mature clams were observed after 2 to 5 weeks of reproductive conditioning at a low temperature (26 °C) and under a constant salinity regime (at 5 or 15 ppt). Higher percentages of spawning and post-stimulation survival as well as spawning response speed were observed in specimens injected in the foot with a low concentration of serotonin (0.4 mL at 20 μM). The time of spawning response onset was shorter in males than in females. The fecundity increased with the live weight of the females, showing an average value of 3.4 × 106 oocytes per female. The early development of the estuarine clam from oocyte to juvenile stage was described in detail. The growth rates of larvae and spat were relatively high but their survival values were low, showing the need for additional research on the larval and post-larval rearing.

Effects of salinity, temperature, and pressure on H2–brine interfacial tension: Implications for underground hydrogen storage

Underground hydrogen (H2) storage is a long-term, clean, and sustainable solution for a large-scale H2 economy. Hydrogen geo-storage strategies in saline aquifers have gained considerable attention regarding meeting energy demand challenges. Rock-fluid interaction and interfacial tension (IFT) of any given gas determine the fluid flow, storage potential, and containment security. However, the literature lacks sufficient information on the IFT of H2-brine systems at various thermophysical and salinity conditions. This study experimentally measures density using an Anton Paar DMA-HP densitometer and IFT with a Kruss drop shape analyzer (DSA-100). The density and IFT measurements of H2-brine systems were evaluated at various pressures (0.1, 5, 10, 15, and 20 MPa), temperatures (25, 50, and 70 °C), and salinities, including deionized water, seawater (mixed brine), and individual brines (NaCl, KCl, MgCl2, CaCl2, and Na2SO4) at 1 and 3 M concentrations. The results indicate a significant decrease in H2-brine IFT by the increasing temperature at a constant pressure and salinity. A slightly decreasing trend is observed when the H2-brine IFT is plotted against pressure, maintaining a constant salinity and temperature. Increasing the salinity of the salt solutions (from 1 to 3 M), irrespective of the salt type, increases the H2-brine IFT at a constant pressure and temperature. Due to the screening effect, the monovalent and divalent cations behave differently in H2. To the best of our knowledge, this comprehensive dataset for H2-brine IFT is presented for the first time. The provided data are crucial for reservoir simulations and determining the H2 geo-storage potential under natural reservoir conditions.

Proteomic profiling of Botryllus schlosseri, an emerging model organism

Botryllus schlosseri is a colonial chordate species that exhibits robust stem cell-mediated regeneration capacities throughout life. It grows through a process of colonial budding known as blastogenesis, in addition to its sexual reproduction mode, embryogenesis. In natural conditions, colony growth peaks in the summer and drastically decreases in the winter due to various seasonal factors. We have established and optimized a method to rear B. schlosseri animals in landlocked laboratories where the controlled conditions allow colonies to grow continuously and exponentially through asexual reproduction under constant temperature, salinity, light, and nutrient conditions. During the weekly blastogenic cycle, all asexually derived parental zooids synchronously regress within one day and are replaced by a new generation. To enable comprehensive molecular phenotyping of this species we established a quantitative proteomics workflow and spectral library for Liquid chromatography/Tandem mass spectrometry (LCMS) data-independent acquisition (DIA). In this study, we quantified the relative abundances of several thousand proteins representing molecular phenotypes of B. schlosseri. This workflow enables us to use proteomics to characterize zooid development during its regenerative cycle, including the short critical period of the takeover stage, during which degenerating zooids undergo massive apoptosis while succeeding buds quickly mature and migrate into place. From this data, protein networks associated with regeneration and degeneration can be created, offering insights into tissue developmental pathways in vivo and future cell immortalization strategies in vitro. Furthermore, the establishment of quantitative proteomics workflows for B. schlosseri coupled with its unique life cycle features promotes the use of this model organism for the study of phenotypic plasticity and evolution of aging, stem cells, and mechanisms of regeneration and cell differentiation. This project is funded by NSF Grant MCB — 2127516. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Surfactant-polymer flood with seawater for a high temperature carbonate reservoir

Developing ultralow tension surfactant formulations for carbonate reservoirs at high temperatures (> 100 °C) in the presence of hard brine is challenging. The target carbonate reservoir had been flooded with seawater and changing of the injection brine (softening or low salinity) for enhanced oil recovery was considered expensive. Seawater was presumed to be the injection brine for this study. The goal of this research work was to develop an ultralow tension surfactant-polymer (SP) formulation with seawater for this carbonate reservoir at 115 °C and to evaluate core floods with and without salinity gradient. Phase behavior was studied for many surfactants and ultralow IFT formulations were identified with the optimal salinity near the seawater salinity. SP core floods were conducted in reservoir sand packs at 115 °C; a novel 2-oven technique was used to collect the effluent with no wax formation and minimal hydrocarbon vaporization. The residual oil saturation was reduced to less than 1% in floods with salinity gradient and about 5% in constant salinity floods (at seawater salinity). The novelty of the work lies in developing SP formulations with seawater at a high temperature and studying the effect of salinity gradient. This process can be considered for many off-shore fields which have been waterflooded with seawater.

A generalized and comprehensive slant channel modeling method for underwater wireless optical communication and its system performance analysis

The underwater wireless slant optical link is a more generalized type of communication links compared with vertical and horizontal links. Since several oceanic factors including temperature and salinity variations with the seawater depth, the performance of the slant link for the underwater wireless optical communication (UWOC) will be overestimated under the assumptions of constant temperature and salinity. To this end, this paper proposes a model of slant link considering the depth-dependent and inclination-angle-dependent turbulence and scattering that are the main causes of multipath fading for UWOC. Specifically, to model the turbulence-induced fluctuations of light fields, the random phase screen method is exploited, where the power spectrum of refractive index is calculated using the oceanic turbulence optical power spectrum (OTOPS) model and the light fields at the receivers are derived by the angular spectrum method. To emulate the scattering-induced divergence, the scattering phase function is applied, where the motion directions and coordinates of light spots propagating among phase screens are deduced using Rodrigues’ Rotation Formula. Simulation results demonstrate the effects of the depths and inclination angles of transmitters on the performance of UWOC by analyzing the scintillation index, channel impulse response, and BER (bit error rate).

Modelling hydraulic plasticity of mangroves

The hydraulic architecture of plants responds to their water availability, mediating between promoting water flow and providing hydraulic safety against embolism. Sites with a constant supply of water favor plants with large vessel diameters, while in dry conditions, narrower vessels are more advantageous. The characteristics of the vessels are primarily shaped by the species’ adaptation to its preferred habitat. However, physiological plasticity enables individual plants to undergo further adaptations to suit specific sites. Mangroves are constantly exposed to low water potentials and therefore hydraulic properties play a pivotal role. Reevaluating studies on vessel diameter distributions and xylem conductivities, we propose a two-parameter gamma distribution description of the hydraulic system. The shape parameter characterizes the species-specific component, and the rate parameter specifies the particular adaptation of the plant to the site salinity. Based on the Hagen–Poiseuille law, we can estimate the xylem conductivity of the plant. Applying this approach to the established single tree model BETTINA, we show the potential plant damage due to salinity shocks for stylized species with different hydraulic properties. Model results suggest that plants with a vessel diameter distribution similar to Rhizophora spp. have an advantage and grow faster under constant salinity conditions due to higher hydraulic conductivities compared to Avicennia-like diameter distributions. This comes at the cost of a higher hydraulic vulnerability to salinity changes of Rhizophora. This approach provides a mechanistic link between site conditions and the hydraulic properties of plants in terms of their ability to physiologically adjust to the site.

Effects of Salinity on the Reproductive Cycle of the Mangrove Oyster Crassostrea tulipa in Hatchery Conditions

Understanding the effects of environmental parameters on the reproductive cycle of shellfish is an essential tool for successful hatchery conditioning management and, consequently, for seed supply to the industry. For the tropical oyster, Crassostrea tulipa, little is known about the factors affecting the maturation process and reproduction, but there are indications that salinity may be of importance. Two experiments were carried out to evaluate the effects of salinity on the reproductive cycle of broodstock of C. tulipa. In the first experiment, oysters were reared in five salinities (40, 35, 30, 25, and 20) for 40 days and gonad histological samples were collected regularly. In a follow up experiment, oysters were reared in variable salinity conditions changing from 40 to 30 or from 20 to 30 over a period of 40 days. Salinity was found to affect the reproductive cycle of C. tulipa. Oysters kept in constant salinity of 30 showed a higher condition index compared to animals in other salinities, with most of the animals in the prespawning stage. Salinity variation was also shown to affect C. tulipa maturation. The prespawning stage was the most observed reproductive stage in low salinity, and high salinity induced a resting stage in the female animals. The results are considered the first step towards developing a protocol for the conditioning of C. tulipa in hatchery conditions.

Genesis and Fluid Evolution of the Hongqiling Sn-W Polymetallic Deposit in Hunan, South China: Constraints from Geology, Fluid Inclusion, and Stable Isotopes

The Hongqiling is a vein-type Sn-W polymetallic deposit in southern Hunan (South China). It is geologically located on the northern margin of the Nanling metallogenic belt. Based on the mineral assemblage and vein crosscutting relationship, three mineralization stages were identified: Sn-W mineralization (S1: cassiterite, wolframite, scheelite, arsenopyrite, molybdenite, pyrite, chalcopyrite, and quartz), Pb-Zn mineralization (S2: chalcopyrite, pyrrhotite, galena, sphalerite, pyrite, quartz, and fluorite), and late mineralization (S3: quartz, fluorite, calcite, galena, sphalerite, and pyrite). According to laser Raman probe analysis, H2O dominates the fluid inclusions in the S1 and S2 stage quartz, with CO2 and trace N2 following close behind. The ore fluid has low salinity, low density, and a wide temperature range, as per our microthermometric data: the S1 stage has homogenization temperatures (Th) of 236–377.6 °C (average 305.3 °C) and salinity of 3.5–10.7 wt.% NaCleqv; the S2 stage has Th of 206.5–332 °C (average 280.7 °C) and salinity of 1.6–5.1 wt.% NaCleqv; and the S3 stage has Th of 170.9–328.7 °C (average 246 °C) and salinity of 0.2–5.9 wt.% NaCleqv. Based on the results of the aforementioned investigation, the fluid inclusions in quartz, fluorite, and calcite are mainly H2O-NaCl vapor-liquid two-phase. Additionally, examinations of inclusions in S1 wolframite and coexisting quartz using infrared and microthermometry show that the mineralizing fluid likewise belongs to the NaCl-H2O system. The Th of inclusions in wolframite is ~40 °C higher than that of coexisting quartz. Moreover, the fluid experienced a decrease in temperature accompanied by nearly constant salinity, which indicates that wolframite precipitation is due to fluid mixing and simple cooling, and the precipitation is earlier than quartz. In situ S and H-O isotope data show that the samples have δ34S = −2.58‰ to 1.84‰, and the ore fluids have δD = −76.6 to −51.5‰ (S1 and S2), and δ18Ofluid = −6.6 to −0.9‰ (S1) and −12.9 to −10.2‰ (S2). All these indicate that the mineralizing fluid was derived from the granitic magma at Qianlishan, with substantial meteoric water incursion during the ore stage. Such fluid mixing and subsequent cooling are most likely the primary controls for ore deposition.

16S rDNA-based diversity analysis of bacterial communities associated with soft corals of the Red Sea, Al Rayyis, White Head, KSA

Coral reef endogenous to the Red Sea ecosystem is one of the largest globally known living reefs that are remarkably distinctive to constant high temperature and salinity. Coral microbiota is one of the most important prespectives contributing to coral survival in such conditions. Four soft corals endogenous to the eastern Red Sea side at Al Rayyis White Head, KSA were collected and identified as Litophyton sp., Sinularia sp., Xenia sp. and Sarcophyton sp. Soft corals-associated microbiota were investigated using Illumina sequencing of bacterial 16S rRNA genes. Results revealed higher bacterial diversity. Assignment of bacterial reads at the phylum level revealed the predominance of Proteobacteria in all coral-associated microbiotas followed by Bacteroidetes and Firmicutes. At the family level, Litophyton sp. was dominated by Hahellaceae, Staphylococcaceae, Prevotellaceae, Moraxellaceae and Bacteroidaceae, while Xenia sp. was dominated by Hahellaceae and Anaplasmataceae. The microbiota of Sinularia sp. were dominated by Pseudomonadaceae and Enterobacteriaceae. Sarcophyton sp. microbiota mainly include members of Enterobacteriaceae only.

The carbonate system and air-sea CO2 fluxes in coastal and open-ocean waters of the Macaronesia

The CO2 system, anthropogenic carbon (Cant) inventory and air-sea CO2 fluxes (FCO2) were analysed in the archipelagic waters of the Macaronesian region. The (sub)surface data were collected during POS533 (February and March, 2019) in coastal areas leeward of Cape Verde (CV), Canary Islands (CA) and Madeira (MA) and through the vessel track. The CO2 variability was controlled by changes in temperature, biological activity and advection processes forced by spatial heterogeneities in the Canary Upwelling System, the mixed layer depth, the mesoscale activity and the circulation patterns. The surface fCO2,sw variability was driven by biological production and CO2-rich water injection in tropical waters and by temperature fluctuations in subtropical waters. The factors controlling the upper ocean changes in the total inorganic carbon normalized to a constant salinity (NCT) were assessed. The uptake and storage of anthropogenic carbon, calculated by using the TrOCA 2007 approach described, as an upper limit, > 60% (>90% above the MLD) of the NCT increase from preformed values. The organic carbon pump accounted 36.6-40.9% for tropical waters and lose importance for subtropical waters (7.5-11.6%), while the carbonate pump has a minimal contribution (<4.2%). The upper-ocean Cant inventory in coastal areas of CV (8,570 Km2), CA (7.960 Km2) and MA (1,250 Km2) was 7.57 x 103, 9.26 x 103 and 8.86 x 103 µmol kg-1, respectively (0.51, 0.58 and 0.09 Tg C, respectively). In terms of FCO2, the CV, CA and MA behaved as a winter CO2 sink (-4.74, -3.90 and -8.34 mmol m-2d-1, respectively) while a strong outgassing was detected over the Cape Blanc filament (20-25 mmol m-2d-1). The total average FCO2 for the ocean area of the three archipelagos (371,250 Km2) was -28.27 Gg CO2 d-1. The POS533 data were compared and compilated with SOCAT and GLODAP data and a new set of equations was provided to calculate the fCO2,sw, Cant and FCO2 in the Macaronesian region based on physical and biogeochemical properties.

Experimental evolution of environmental tolerance, acclimation, and physiological plasticity in a randomly fluctuating environment.

Environmental tolerance curves, representing absolute fitness against the environment, are an empirical assessment of the fundamental niche, and emerge from the phenotypic plasticity of underlying phenotypic traits. Dynamic plastic responses of these traits can lead to acclimation effects, whereby recent past environments impact current fitness. Theory predicts that higher levels of phenotypic plasticity should evolve in environments that fluctuate more predictably, but there have been few experimental tests of these predictions. Specifically, we still lackexperimental evidence for the evolution of acclimation effects in response to environmental predictability. Here, we exposed 25 genetically diverse populations of the halotolerant microalgae Dunaliella salina to different constant salinities, or to randomly fluctuating salinities, for over 200 generations. The fluctuating treatments differed in their autocorrelation, which determines the similarity of subsequent values, and thus environmental predictability. We then measured acclimated tolerance surfaces, mapping population growth rate against past (acclimation) and current (assay) environments. We found that experimental mean and variance in salinity caused the evolution of niche position (optimal salinity) and breadth, with respect to not only current but also past (acclimation) salinity. We also detected weak but significant evidence for evolutionary changes in response to environmental predictability, with higher predictability leading notably to lower optimal salinities and stronger acclimation effect of past environment on current fitness. We further showed that these responses are related to the evolution of plasticity for intracellular glycerol, the major osmoregulatory mechanism in this species. However, the direction of plasticity evolution did not match simple theoretical predictions. Our results underline the need for a more explicit consideration of the dynamics of environmental tolerance and its underlying plastic traits to reach a better understanding of ecology and evolution in fluctuating environments.

Effects of constant and fluctuating saltwater addition on CH4 fluxes and methanogens of a tidal freshwater wetland: A mesocosm study

The importance of salinity in regulating CH4 emissions from coastal tidal wetlands has been widely recognized. However, the different effects of constant versus fluctuating salinity increases on CH4 emission and methanogens in both tidal freshwater marsh and floodplains are not yet well understood. We constructed mesocosm experiments on both a Cyperus malaccensis marsh and an adjacent non-vegetation-covered tidal floodplain over one year. We examined the effects of constant freshwater (CF), constant salinity (CS), and fluctuating salinity (FS) on porewater geochemistry, CH4 flux, methanogen abundance, diversity, and community structure in the tidal marsh and floodplain. Compared with CF treatment, methanogen abundance and Chao1 index were significantly lower in the marsh mesocosms under FS and CS treatment, but only in the floodplain mesocosms under CS treatment. CS treatment significantly reduced the proportion of Methanosarcinales but significantly increased the proportion of Methanobacteriales. Porewater SO42− and Cl− concentrations and pH were important factors affecting methanogen abundance and diversity. Both the CS and FS treatments considerably reduced CH4 fluxes in marsh and floodplain mesocosms; the main factor impacting CH4 flux was porewater dissolved CH4 concentration, and both methanogen abundance and Chao1 index were positively correlated with CH4 flux. Our results suggest that both continuous saltwater intrusion caused by sea-level rise and pulse saltwater intrusion perhaps caused by typhoons could reduce CH4 flux from subtropical estuarine tidal freshwater wetlands.

Simulation of Fluid Flow during Egg Pickling under Different Inlet and Outlet Conditions in a Pulsed Pressure Tank with Liquid Circulation.

Pulsed pressure pickling is an emerging highly efficient osmotic dehydration technique. However, the immobility of the pickling liquid and the material, the formation of layers, and the uneven pickling efficiency in different sections make it difficult to use industrially. This work aims at improving and optimizing the conditions of fluid flow in the pickling tank with a liquid-cycle system to reduce the unevenness in the production process. Fluid flow around the eggs was numerically investigated by solving three-dimensional Reynolds-averaged Navier–Stokes equations within the flow regime, adopting different angles and positions at the inlet and outlet. The simulation results show that the inlet with a radial deflection of 35° and the outlet with axial direction were characterized by the best flow efficiency. Under these conditions, the average flow velocity and the global uniformity index were 0.153 m/s and 0.407, respectively. Furthermore, the experiments were carried out using an equivalent scale model of the pulsed pressure equipment with liquid circulation. The experimental results showed that, under optimal conditions, the salt content in all four layers of the egg white was about 2.8% after 48 h. This study provides a solution to ensure the constant salinity of different layers of pickled eggs and to improve pickling efficiency, especially in industrial-scale production.

A Plea for More Skepticism Toward Fluid Inclusions: Part II. Homogenization via Halite Dissolution in Brine Inclusions from Magmatic-Hydrothermal Systems Is Commonly the Result of Postentrapment Modifications

AbstractQuartz-hosted brine inclusions that homogenize via halite dissolution occur in many magmatic-hydrothermal systems. In many cases their calculated minimum entrapment pressures are geologically unrealistically high, which has been interpreted to reflect accidental entrapment of halite crystals, and hence, to indicate halite saturation. Here it is demonstrated based on microthermometric trends and laser ablation-inductively coupled plasma-mass spectrometry analyses of fluid inclusion assemblages from eight different ore deposits that the phenomenon of inclusion homogenization via halite dissolution is commonly caused by postentrapment changes in fluid inclusion volume rather than by cotrapping of halite. Many of the investigated assemblages show highly variable liquid-vapor homogenization temperatures at relatively constant fluid salinity—a trend that cannot be produced by cotrapping of halite or by cotrapping of vapor. Furthermore, in those assemblages that do display variable fluid salinities, the elemental Cl/X concentration ratios (where X denotes any element other than Na) do not increase with increasing fluid salinity. The observed microthermometric and compositional trends are best explained by variable extents of postentrapment reduction in inclusion volume, which increased fluid density and in some cases was accompanied by H2O loss and migration of the inclusions within the host quartz. The fact that such trends can be observed even in seemingly well preserved fluid inclusion assemblages suggests that postentrapment modifications in fluid inclusion volume and H2O contents may be widespread and thus that temperature and pressure estimates from quartz-hosted fluid inclusions should generally be treated with caution. This is particularly true for samples that may have experienced deformation, such as massive quartz veins and rock-forming quartz.