Salinity Variations Research Articles

The influence of variations in salinity levels on the biocementing process on soil improvement of liquefaction potential

Abstract This article presents an innovative method of soil improvement cementing to increase the shearing strength of very loose sand with 10% relative density (Dr) in saline conditions. Salt in saline soils destroys the stability of stable soils. In contrast, the salt content reduces the level of homogenization of unstable soils, causes technical problems in calcareous soils, and affects their stability, especially if the salt content is more than 3.0%. The variations in salinity levels can determine the optimal percentage of salt levels in the stabilized soil. The application of biocementation to saline soil can drastically increase the shear strength of soil in soil with potential liquefaction in coastal areas due to earthquakes. Calcium carbonate deposition (MICP) in the microbial-induced biocementing process is a new method that utilizes the metabolic processes of microorganisms in this study using Bacillus sp. In the MICP process, microbes need Ca2+ ions obtained from fly ash, which can produce SiO2 and CaO to produce CaCO3 for binding between particles. Soil improvement was carried out by combining initial soil, fly ash, mycobacteria, and variations in salinity obtained from NaCl with varying percentages of 0%, 1%, 2%, and 3,4% after testing at curing times 7, 14, 21, and 28 days. The research samples from the UCS and direct shear tests showed that the shear and UC strength that were treated increased. The highest increase in shear strength was at 3,4% salinity at 28 days of 80.9°. CaCO3 production resulting from the binding between particles in the biocementing reaction can be seen from the results of SEM tests. Soil improvement using biocementing in this study resulted in an effective increase in the strength of loose sand soil in salinity condition.

Site‐Specific Multiple Stressor Assessments Based on High Frequency Surface Observations and an Earth System Model

AbstractGlobal Earth system models are often enlisted to assess the impacts of climate variability and change on marine ecosystems. In this study, we compare high frequency (daily) outputs of potential ecosystem stressors, such as sea surface temperature and surface pH, and associated variables from an Earth system model (GFDL ESM4.1) with high frequency time series from a global network of moorings to directly assess the capacity of the model to resolve local biogeochemical variability on time scales from daily to interannual. Our analysis indicates variability in surface temperature is most consistent between ESM4.1 and observations, with a Pearson correlation coefficient of 0.93 and bias of 0.40°C, followed by variability in surface salinity. Physical variability is reproduced with greater accuracy than biogeochemical variability, and variability on seasonal and longer time scales is more consistent between the model and observations than higher frequency variability. At the same time, the well‐resolved seasonal and longer timescale variability is a reasonably good predictor, in many cases, of the likelihood of extreme events. Despite limited model representation of high frequency variability, model and observation‐based assessments of the fraction of days experiencing surface T‐pH and T‐Ωarag multistressor conditions show reasonable agreement, depending on the stressor combination and threshold definition. We also identify circumstances in which some errors could be reduced by accounting for model biases.

Impacts of high salinity on antifouling performance of hydrophilic polymer-modified reverse osmosis (RO) membrane

Reverse osmosis (RO) is a crucial process for treating waters across various salinity levels, but membrane fouling persists as an inherent challenge. While surface modification with hydrophilic polymers such as polyethylene glycol (PEG) and its derivatives is a prevailing strategy to alleviate fouling, its effectiveness has primarily been explored in low-salinity conditions, leaving a critical knowledge gap regarding the performance of such membranes in high-salinity environments and their susceptibility to feed salinity variations. We here investigated the antifouling characteristics of PEG-modified RO membranes for high-salinity wastewater and seawater treatment. Remarkably, our findings indicated a substantial decrease in fouling resistance under high-salinity conditions compared to low-salinity wastewaters used as control. The reduction in Lewis acid-base interactions, induced by decreased water structuring, was found to be a critical factor for the diminished fouling resistance based on the Extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) analysis. Complementary experimental and theoretical studies unveiled the disruptive role of high-concentration NaCl on PEG-water hydrogen bonds, causing PEG dehydration and configurational compression, which thus compromised the enthalpic barrier and entropic repulsion against fouling. Our study emphasizes the pivotal role of feed salinity in determining the fouling resistance of membranes modified with hydrophilic polymers, a factor often neglected in prior research.

SALINE MAPS OF SOME SOILS OF MUTHANNA GOVERNORATE

performed based on data collected from 15 soil samples from 0 to 20 cm deep. We used salinity of the irrigated soils of Al-Muthana governorate in southern Iraq. These maps were 20% of the world's land. This study was made in order to map the spatial distribution of soil or anthropogenic processes, which is certainly an environmental problem that affects more than environment and agricultural production. The main causes of this salinization come from natural It is important to study the problem of salinization, soil salinity has adverse effects both on the ordinary kriging (OK) to analyze the spatial variability of soil salinity, The results confirmed that the use of saline maps was supportive in giving a clear vision of the of 12.11 dS m-1, for developing probability maps to determine the distribution of risk areas. showed the different classes of salinity with the highest value of 23.17 dS m-1 and lowest value map predicted by the electrical conductivity (EC) values using the ordinary kriging (OK) method while indicator kriging (IK) was used to analyze salinity versus threshold values . The salinity salinity of the soils for the study area

Interannual Variation of Summer Sea Surface Salinity in the Dotson–Getz Trough, West Antarctica

In this study, we explore the interannual variability of Sea Surface Salinity (SSS) in the Dotson–Getz Trough located in West Antarctica, focusing on the month of February. Utilizing the oceanic analysis product EN4, we first validate the EN4 SSS with data from a singular ship-based survey, and then delve into potential factors that may influence SSS, with a particular emphasis on surface freshwater flux, sea ice concentration (SIC), and also the surface stress curl, which will induce upwelling via Ekman transport to affect the SSS. Our findings primarily indicate a link between SSS and sea ice concentration, showcasing a negative correlation where the peak (average) coefficient is around −0.6 (−0.4), further affirming the substantial interannual variability of SSS in this region.

Metabolite Compounds of Euglena sp. on Mass Cultivation System under MgCl2 and CaCl2 Salt Stress

Euglena sp. is rich in primary and secondary metabolite compounds. This cosmopolitan organism can survive extreme conditions such as salt stress because it can increase cell growth rate and metabolism. This mass cultivation research uses an open pond system that is very vulnerable to contamination, so variations in salinity of MgCl2 and CaCl2 are used as treatments because they minimize contamination. The research examines the correlation of salt types to cell growth rate, biomass, monosaccharide profile, paramylon, pigment, and lipid of Euglena sp. Research methods include preparation, medium making, mass cultivation, and measurement of test parameters. Data were analyzed through One-Way ANOVA followed by DMRT, with a 5% confidence level. Based on the research result, the highest value of biomass and paramylon content and productivity at CaCl2 treatment with consecutive values 0.013 ± 0.001, 0.002 ± 0.000, 9.556 ± 0.070, and 0.149 ± 0.019. Monosaccharides analysis produced in the form of sucrose, glucose, fructose, and arabinose amounted to < 10 ppm. CaCl2 treatment produced the highest sucrose of 6251 ppm. The highest chlorophyll-a and carotenoid pigments are located at CaCl2 treatment, respectively (1.698 ± 0.051)b and (0.500 ± 0.032)b. At the same time, the salt treatment has a significant effect on lipid content. To summarize, almost all metabolite compounds were highest in CaCl2 treatment. This research is expected to contribute to developing the Euglena sp. mass cultivation system as a source of bioenergy and biomaterials.

Species-specific metabolome changes during salinity downshift in sub-Arctic populations of Mytilus edulis and M. trossulus

The blue mussels Mytilus edulis and Mytilus trossulus are ecologically and economically important species distributed widely across the Northern Hemisphere. Understanding their behavioral and physiological disparities is crucial for assessing their ecological success and aquacultural value. The recent finding of non-native M. trossulus in the White Sea raises concerns regarding its potential competition with native M. edulis and its prospective spread in light of climate change and surface water freshening. We investigated the responses of M. edulis and M. trossulus to salinity variations by examining shell closure thresholds and tissue levels of 35 metabolic intermediates in mussels acclimated to different salinities (25, 16, and 10). The salinity threshold for valve closure was similar in both studied species, but M. trossulus consistently opened at lower salinities (by 0.2–0.7 practical salinity units) compared to M. edulis. Salinity-induced changes in metabolite levels were similar between the two species. Taurine emerged as the dominant osmolyte, comprising over 50% of the total free amino acid pool, with aspartate and glycine contributing 15–30%. Concentrations of taurine, glycine, and total free amino acids declined with decreasing salinity. Taurine to glycine ratios were higher in M. edulis and increased in both species with declining salinity. Acclimation salinity significantly influenced urea cycle intermediates and methionine sulfoxide content, a cellular biomarker of amino acid oxidation. Species-specific differences were observed in purine metabolism, with higher levels of GMP and AMP found in M. edulis. Likewise, aromatic amino acids and histidine levels were higher in M. edulis compared to M. trossulus. However, no evidence suggests superior adaptation of M. trossulus metabolism to hypoosmotic stress compared to M. edulis. Further research is necessary to elucidate the functional implications of subtle metabolic differences between these Mytilus congeners and their ecological consequences in changing marine environments.

Evaluation Method for Underwater Ultrasonic Energy Radiation Performance Based on the Spatial Distribution Characteristics of Acoustic Power.

In recent years, underwater wireless ultrasonic energy transmission technology (UWUET) has attracted much attention because it utilizes the propagation characteristics of ultrasound in water. Effectively evaluating the performance of underwater ultrasonic wireless energy transmission is a key issue in engineering design. The current approach to performance evaluation is usually based on the system energy transfer efficiency as the main criterion, but this criterion mainly considers the overall energy conversion efficiency between the transmitting end and the receiving end, without an in-depth analysis of the characteristics of the distribution of the underwater acoustic field and the energy loss that occurs during the propagation of acoustic waves. In addition, existing methods focusing on acoustic field analysis tend to concentrate on a single parameter, ignoring the dynamic distribution of acoustic energy in complex aquatic environments, as well as the effects of changes in the underwater environment on acoustic propagation, such as spatial variability in temperature and salinity. These limitations reduce the usefulness and accuracy of models in complex marine environments, which in turn reduces the efficiency of acoustic energy management and optimization. To solve these problems, this study proposes a method to evaluate the performance of underwater ultrasonic energy radiation based on the spatial distribution characteristics of acoustic power. By establishing an acoustic power distribution model in a complex impedance-density aqueous medium and combining numerical simulation and experimental validation, this paper explores the spatial variation of acoustic power and its impact on the energy transfer efficiency in depth. Using high-resolution spatial distribution data and actual environmental parameters, the method significantly improves the accuracy of the assessment and the adaptability of the model in complex underwater environments. The results show that, compared with the traditional method, this method performs better in terms of the accuracy of the acoustic energy radiation calculation results, and is able to reflect the energy distribution and spatial heterogeneity of the acoustic source more comprehensively, which provides an important theoretical basis and practical guidance for the optimal design and performance enhancement of the underwater ultrasonic wireless energy transmission system.

Transient internal wave excitation of resonant modes in a density staircase

The density of the ocean generally increases continuously with depth as a consequence of variations in salinity and temperature. In some regions, however, the density profile of the ocean adopts a (double diffusive) staircase structure in which successive layers of uniform density fluid are separated by rapid density jumps. Previous work has theoretically examined the transmission and reflection of periodic internal (gravity) waves incident upon a density staircase. This predicted the existence of transmission spikes (global modes) for certain combinations of frequency and horizontal wave number in which the incident waves transmit perfectly across a density staircase. It was hypothesized that the transmission spikes occur when the incident waves resonate with natural modes of disturbances in the staircase. Here we derive theory to investigate the interactions between incident internal waves and modes. We demonstrate a close correspondence between the frequency for incident waves at a transmission spike and the real part of the frequency of modes at the same horizontal wave number. However, the frequency of the corresponding modes has a negative imaginary part corresponding to exponential decay of the modes in time. We perform numerical simulations to examine the impact of this near-resonant coupling when a vertically localized, quasimonochromatic internal wave packet interacts with a density staircase. In a range of simulations with fixed incident wave frequency and varying horizontal wave number, the measured transmission coefficient does not exhibit transmission spikes, but decreases monotonically with increasing horizontal wave number about the critical wave number separating strong and weak transmission. We show this occurs because the incident wave excites modes that then slowly transmit energy above and below the staircase at a rate consistent with the predicted decay rate of the modes. This rate is slower for staircases with more steps with the decay time increasing as the cube of the number of steps. Published by the American Physical Society 2024

Fossil oysters from the southernmost coast of Brazil: Bioerosion and palaeoenvironmental implications

Fossil oysters are commonly found in Rio Grande do Sul Coastal Plain (RSCP), where the main species are Ostrea cf. puelchana d’Orbigny, 1841 and Crassostrea praia Ihering, 1907. These fossils are transported towards the beach by storm events throughout the year, being available in the swash zone. The objective of this article is to reconstruct the Holocene palaeoenvironment by analysing these fossils. A total of 1898 valves, collected along Cassino and Hermenegildo beach, both in southernmost Brazil, were described. It was observed a prevalence of C. praia at Cassino beach (39.20%) and O. cf. puelchana at Hermenegildo beach (89.02%). Hermenegildo beach sample were statistically greater for C. praia height ( p-value: 0.1736) and length ( p-value: 0.4604) and for O. cf. puelchana height ( p-value: 0.0602) and length ( p-value: 0.07394). The predominance for northern and southern regions for each species indicates a palaeoenvironment setting that favoured these organisms, probably related to temperatures and salinity variation. The most common ichnogenera found in the oysters were Caulostrepsis and Entobia present in both sites, observed in over 40% of internal and external sides of the samples’ shell. According to radiocarbon modelled age, the studied samples coexisted during the Mid-Holocene (8.290–8.130 cal. yr. BP), with the subsequent sea-level rise and fall the shells became bioavailable. The lack of samples with closed valves and high percentage of bioerosion in the inner side of the valve, indicates that the palaeoenvironment in both Cassino and Hermenegildo beaches gradually changed, not as result of an extreme event.

Mesoscale and climate environmental variability drive krill community changes in the Humboldt Current System

Euphausiids (or “krill”) play a crucial role in the food webs of eastern boundary upwelling systems. Their inter-specific predatory interactions with ecologically and commercially important species highlights the importance of understanding krill variability at different temporal and spatial scales. In the Humboldt Current System (HCS), few studies have addressed the spatio-temporal variability of krill communities and their link with climate and local environmental drivers. We studied the patterns and variability of euphausiid diversity in the coastal area off northern Chile, using zooplankton and CTD-O data, and satellite environmental data from the falls and springs of 2010–2017. The community showed low diversity and evenness, with the endemic species Euphausia mucronata being the most abundant. The environmental variance showed 2 main modes of variability: (1) upwelling-associated changes in the depth of the oxygen minimum zone (OMZ) and in temperature, and (2) interannual variability in salinity, associated with ENSO-driven water-mass changes. The diversity indices and community structure showed large fluctuations in the cross-shore direction, and with latitude. The general pattern showed higher diversity offshore and southward, with few species in the low temperature, shallow OMZ conditions of the coastal band. During the 2013 and 2016 marine heatwaves and the 2015-2016 El Niño, the Subtropical Water Mass was advected southward, causing an increase in salinity and temperature, and a decrease in total krill abundance. However, ENSO variability did not significantly affect the species composition. The changes in community structure were caused by fluctuations in species abundance rather than species presence, as the most abundant species dominated the community throughout the study period. These results indicate that the krill communities of the HCS are highly resilient to climate perturbations, with upwelling-associated gradients being the primary source of variability for euphausiid populations in this ecosystem.

Assessment and mapping of soil salinity and groundwater quality in Nijhum Island, Hatiya Upazila, Noakhali

Crop yield is heavily influenced by soil salinity. The objective of the research is to assess the depth wise soil salinity distribution pattern and groundwater quality by measuring physico-chemical parameters in the agricultural land of Nijhum Island, Noakhali, Bangladesh. This study also explicates the spatial variation of soil salinity in the study area. Soil samples were collected from three different depths to estimate the Electrical Conductivity (EC) using a paste of 1:5 soil and distilled water suspension (1:5 weight-to-volume method). Spatial analyst tool of ArcGIS was used and observed that the land of Nijhum Island was affected with severe salinity in almost 85% of sampling plots and 15% of sampling plots were extremely saline. The soil salinity process has been noticed due to seawater intrusion from the Bay of Bengal through the Meghna estuary which threatens crop production and soil fertility, threatening the population's livelihood. This study provides a baseline understanding of soil salinity in Nijhum Island to help decision-makers and smallholder farmers improve their livelihoods. Thus, groundwater depth did not affect soil salinity significantly. The result contradicts most studies that found a strong influence on soil salinity. Because the study area is coastal, most of the salt comes from seawater inundation and capillary rise, which reduces groundwater availability.

Reversibility of seawater intrusion in a coastal aquifer: Insights from long-term field observation and numerical modeling

It is essential to understand basis processes affecting the reversibility of seawater intrusion (SWI) and the related timescale after groundwater pumping stopped for coastal groundwater management. Groundwater salinity variations presented by previous studies showed a fast SWI process and the following seawater retreat (SWR) process indicated by overall salinity decrease in the coast karst aquifer in the Dalian Peninsula, northeast China. Cross-sectional variable-density flow and transport simulations using equivalent porous medium (EPM) model, dual-domain (DDM) model and the EPM with a single discrete feature representative of conduit flow (EPM-DF) are conducted to understand the SWI reversibility related to the characteristics of the flow system, including aquifer parameters and seaside boundary conditions. Large dispersity combined with a low salinity concentration at the sea boundary are necessary in the EPM and DDM models to produce a fast SWI and low salinity concentration as observed. The enhanced dispersion in the DDM model enhances the mixing in the transition zone (TZ) and produces more obvious seasonal variation but longer SWR process compared to the EPM model. The EPM-DF model produces significant salinity seasonal variation during the SWI process and a fast decrease in the SWR process. The overall fast system response but low peak concentration during the SWI might be attributed to the highly heterogeneous characteristics of the karst aquifer system, which produces a wide front edge of TZ as observed. The dispersion-dominated EPM and DDM models produced higher degree of SWI reversibility compared to the EPM-DF model, as indicated by the weaker lag effects between groundwater levels and salinity concentration. Moreover, the SWI reversibility may arise not only from the heterogeneous characteristics of the karstic aquifer system but also from the rate for rise in the inland groundwater level during the seasonal variation cycle. An overall SWR process can be divided into two stages: the first stage with rapid decrease in salinity concentration but small changes in toe associated with TZ widening and the second stage with rapid toe retreat during aquifer flushing. The flushing of the brine leakage from the solar salt field may extend the SWR process. Considering this relatively longer water quality response time than the time span in general groundwater management plans, a reasonable objective and how maintain the hydraulic head during the SWI controlling have been of a great concern to the coastal groundwater management.

Hydro-ecological modelling of a hypersaline lagoon ecosystem (Pulicat) in Southeast coast of India

Climate change impacts the coastal lagoons and can affect various species reproductive cycles, feeding habits, and survival. Due to natural factors, the ecosystem habitat at Pulicat Lagoon on the east coast of India is under severe stress. This study assesses the ecosystem using a numerical model and field-collected physical, chemical, biological, and meteorological data for 2018 and 2019. A coupled hydro-ecological model was used to analyze circulation features, biological and chemical interactions, and transformation processes. The study indicates that high abnormalities in the lagoon ecosystem are caused by less exchange of fresh/coastal water from river sources and sea mouths due to less rainfall during the study period. The model output depicts the salinity variation from 15 to 58 PSU in different seasons of 2018 and 2019. Furthermore, high concentrations of Chl-a ranged from 50 μg/L to 95 μg/L during the monsoon and post-monsoon seasons, triggering phytoplankton C (70–350 mg/m3) and zooplankton C (9–43 mg/m3) at the Lagoon, resulting in an algal bloom. The monsoonal shift of Chlorophyte (9.52%–9.68%), Cyanobacteria (13.22%–14.95%), Diatoms (66.08%–63.87%), and Dinoflagellates (11.18%–11.51%) is observed in the biological field, with Diatom showing the highest abundance (65%). As a result, appropriate scenario-based model studies were conducted to conserve and strengthen the ecosystem during such extreme events. The model studies suggest that widening the lagoon inlet (800m) with a depth of 5 m (3 km length) increases the optimal tidal exchange to the ecosystem. The model output demonstrates the optimal exchange that normalizes the salinity from 12 to 34 PSU from the inner Lagoon to the mouth region. This study will support environmental authorities in conserving the ecosystem through proper management adaptations.

Assessing CMIP6 models in simulating meteo-oceanographic variability on Spanish continental coasts

The ocean is a key player in the Earth's climate, absorbing heat and carbon dioxide from the atmosphere. The ocean's temperature and salinity are influenced by climate change, which can significantly impact marine ecosystems. Reliable data sets of atmospheric and oceanographic parameters are of special interest in coastal productive areas to adequately monitor their variability at regional and local levels. It is therefore essential to continue monitoring and studying the ocean to develop effective mitigation and adaptation strategies. In this context, the main aim of this study is to identify the Earth System Models (ESMs) from the Coupled Model Intercomparison Project 6 (CMIP6) that best capture the variability of water temperature, salinity, and wind speed along the continental Spanish coasts, using them to estimate future impacts in these regions. To achieve this, a multifaceted approach is used, encompassing a historical (2000−2014) assessment comparing ESM outputs to in situ observations from Puertos del Estado (PdE) oceanographic buoys, an examination of the present period (2015−2022) under three IPCC scenarios (SSP1−2.6, SSP2−4.5, and SSP5−8.5), and a projection of future (2023−2100) trends using the same emission scenarios. Results showed that the ESMs from CMIP6 can reproduce the historical patterns of meteo-oceanographic properties, rendering them valuable tools for climate change studies. In the future (2100), considering the most pessimistic scenario (SSP5−8.5), the water temperature may increase by 2.8°C, salinity may decrease by -1.6, and wind speed may decrease by -0.4 m·s−1. These projected changes can significantly impact the Spanish coasts, jeopardizing the growth, reproduction, survival, abundance, and distribution of some marine species.

Draw-tower-grating-based Fabry-Perot interferometers for simultaneous measurements of temperature and salinity.

In this paper, a fiber optic sensor with draw-tower-grating (DTG)-based Fabry-Perot interferometers (FPIs) are proposed to measure the temperature and salinity of seawater simultaneously. The sensing structure utilizes DTG as the reflector, and two adjacent gratings can be cascaded to compose an FPI. By employing moisture-sensitive materials to the surface of the optical fiber, the variation in salinity can be measured by the axial strain applied by the coating on the sensing optical fiber. The salinity altering causes swelling or shrinking actions of the coating through absorbing or releasing water. Two different moisture-sensitive materials are chosen to eliminate the cross-sensitivity of temperature and salinity. The experimental results show that the sensor exhibits linear response to temperature and salinity changes with good repeatability and stability, and the temperature and salinity sensitivities are 12308.65 rad/°C and 95.02 rad/‰, respectively. The optical path configuration of the DTG sensing array matching compensation interferometer provides the possibility for efficient distributed solutions, which has promising potential for application in marine engineering.

Congeneric and sympatric tropical mullets respond differently to environmental variability: insights into coexistence

Context Disentangling mechanisms influencing the seasonal and spatial distribution of fish is essential to understanding population dynamics. In the south-western Atlantic, the sympatric mullets Mugil curema and M. rubrioculus are closely related and use habitat similarly. However, which processes allow their coexistence is unknown. Aims We tested the hypothesis that the two species exhibit temporally and spatially decoupled habitat-use patterns to allow sympatry due to different responses to environmental drivers. Methods Bayesian zero-inflated count models were used to unravel spatial and temporal distribution patterns of those species in a south-western Atlantic lagoon. Key results The two species display different distributions within the estuary, being spatially and temporally segregated, with M. curema mostly inhabiting the inner estuary and M. rubrioculus inhabiting coastal marine habitats. Conclusions This decoupling in habitat use might be driven by distinct responses to environmental variability: M. curema is influenced by factors such as temperature and dissolved oxygen, whereas M. rubrioculus is influenced by variations in salinity. We suggest that the studied species evolved divergent responses to environmental variation to allow coexistence. Implications This study suggests that environmental factors drive mullet abundance, and that zero-inflated count models incorporating those drivers are therefore useful in predicting their spatial and temporal distribution, as well as in standardising abundance trends for stock assessment efforts.

Generating a monthly variability of sea surface salinity based on source tracing of salt concentration and the estimated SEBAL-evaporation

Abstract The variation and spatial distribution of sea surface salinity (SSS) depend on the geographic condition of the water surfaces and the temporal variation of atmospheric conditions. The SSS might differ in a local coastal area compared to similar situations in global and regional oceans. The SSS values have been estimated based on spatial regression of extracted water-salt concentration as a source tracing of salt against corrected Landsat 8 satellite data during the drought season of April 2023. Here, the electrical conductivity (EC) from the Cimanuk River can be used as primary data. This result, paired with the evaporation-derived surface energy balance algorithm for land (SEBAL) algorithm, explains a monthly SSS variability after the validation using pre-defined resampled regional SSS and evaporation data. The result shows variations in estimated SSS values along with fluctuated SEBAL evaporation ranging from 1.64 to 1.62 dS/m and 1.04 to 0.41 W/m2, respectively. It describes monthly variability and their relationship in a local coastal area limited to the condition of a drought season. However, the validation shows that the root means square error (RMSE) of 1.00 from the SSS map, produced by the regression model involving band 7 of Landsat 8 and 9, has satisfied the reasonable SSS value ranges besides the best accuracy.

Phenotypic plasticity in the sailfin molly III: Geographic variation in reaction norms of growth and maturation to temperature and salinity.

Phenotypic plasticity, the ability of a single genotype to produce different phenotypes under different environmental conditions, plays a profound role in several areas of evolutionary biology. One important role is as an adaptation to a variable environment. While plasticity is extremely well documented in response to many environmental factors, there is controversy over how much of that plasticity is adaptive. Evidence is also mixed over how often conspecific populations display qualitative differences in the nature of plasticity. We present data on the reaction norms of growth and maturation to variation in temperature and salinity in male and female sailfin mollies (Poecilia latipinna) from three locally adjacent populations from South Carolina (SC). We compare these reaction norms to those previously reported in locally adjacent populations from north Florida (NF). In general, patterns of plasticity in fish from SC were similar to those in fish from NF. The magnitude of plasticity differed; fish from SC displayed less plasticity than fish from NF. This was because SC fish grew faster and matured earlier at the lower temperatures and salinities compared to NF fish. This is a countergradient pattern of variation, in which SC fish grew faster and matured earlier in conditions that would otherwise slow growth and delay maturity. Among fish from both regions, males were much less plastic than females, especially for length at maturity. While there was no detectable heterogeneity among populations from NF, males from one of the SC populations, which is furthest from the other two, displayed a qualitatively different response in age at maturity to temperature variation than did males from the other two SC populations. The pattern of population variation in plasticity within and among regions suggests that gene flow, which diminishes with distance in sailfin mollies, plays a critical role in constraining divergence in norms of reaction.

Drivers of Interannual Salinity Variability in the Arctic Ocean

AbstractAccurate projections and attribution of Arctic Ocean changes in climate models require a good understanding of the mechanisms underlying interannual salinity variability in the region. Although some mechanisms have been extensively studied in idealized setting, in particular for the dynamics of the Beaufort gyre (BG), it remains unclear how applicable they are to more complex systems. This study introduces a new diagnostic based on salinity variance budget to robustly assess the mechanisms of salinity variations. The diagnostic is then applied to the “Estimating the Circulation and Climate of the Ocean” state estimate. Results indicate that the advection of salinity anomaly in the direction of the mean salinity gradient made by velocity anomalies is the primary source of interannual salinity variability. These velocities are primarily attributed to fluctuating winds via Ekman transports. Fluctuating surface freshwater fluxes from the atmosphere and sea ice are the second most important source of variability and cannot be neglected. The two sinks of interannual salinity variance are associated with the erosion of large scale gradients of the mean circulation by eddies and to a lesser extent to the diffusive terms. Over continental shelves, particularly over the East Siberian Shelf (ESS), ocean surface freshwater fluxes and diffusion play a more important role than in the deep basins. We also report a strong intensification of all sources and sinks of interannual salinity variability in the BG and an opposite weakening in the ESS in the second decade of the analysis (2004–2014) with respect to the first (1993–2003).