Search Results (1,980)

Groundwater quality in arid and semi-arid regions is increasingly affected by salinization, evaporation, abstraction, and agricultural return flow. This study evaluates the hydrochemical evolution, isotopic characteristics, ²²²Rn activity, and water-use suitability of groundwater and associated waters in Karbala Governorate, central Iraq. Seventeen groundwater, lake water, and municipal supply water samples were analyzed for physicochemical parameters, major ions, δ¹⁸O, δ²H, and ²²²Rn. Hydrochemical, isotopic, and water-quality assessment methods were applied to evaluate groundwater evolution, salinization, and suitability for drinking and irrigation. The waters are near-neutral, with pH values of 6.18–7.35, but are strongly mineralized. Electrical conductivity ranges from 1440 to 16,305 µS/cm, and total dissolved solids (TDS) range from 592 to 10,191 mg/L. Most samples belong to a Ca–Mg–SO₄–Cl facies, indicating sulfate- and chloride-rich hard water evolution. The highest mineralization occurs near Karbala proper and lake-influenced sites. Ion ratios and chloro-alkaline indices indicate that evaporite dissolution, gypsum/anhydrite dissolution, carbonate interaction, evaporation, and local ion exchange jointly control groundwater chemistry. Stable isotopes indicate meteoric origin with variable evaporative enrichment; however, highly saline but isotopically depleted water, particularly W8, shows that evaporation alone cannot explain salinization. ²²²Rn activities range from below detection to 11.28 Bq/L and mainly reflect local aquifer contact and degassing. High TDS, sulfate, chloride, and very high hardness limit suitability for drinking-water use. For irrigation, the sodium hazard is low, but salinity, hardness, magnesium hazard, and permeability constraints make most samples unsuitable or restricted. Management should prioritize salinity and hardness control, treatment or blending before domestic use, restricted irrigation of the least saline wells under drainage and soil-salinity monitoring, protection of less mineralized recharge zones, and long-term monitoring of lake-adjacent and agriculturally influenced wells. Full article

Soil water availability, salinity dynamics, and nitrate transport are key factors controlling agricultural sustainability in arid environments characterized by limited water resources and high evaporative demand. This study evaluated the combined effects of soil texture, nitrate–nitrogen application, and sawdust mulching on soil water retention, evaporation losses, salinity redistribution, and nitrate movement in loamy sand and sandy clay loam soils under controlled greenhouse conditions. Results showed that soil texture was the dominant control on hydrochemical behavior, with sandy clay loam exhibiting higher water retention and lower drainage than loamy sand. Sawdust mulching significantly improved soil water conservation by reducing evaporation and stabilizing moisture distribution, while the 4 cm mulch treatment achieved the highest overall CSI performance. Evaporation strongly governed salinity accumulation in surface layers, whereas mulching reduced salt build-up and promoted a more uniform salinity profile. Nitrate transport closely followed water fluxes, resulting in higher leaching in loamy sand and greater retention in sandy clay loam. Increasing nitrogen application enhanced nitrate mobility and leaching in both soils. A Composite Sustainability Index (CSI) was developed to integrate soil water conservation, evaporation reduction, salinity control, and nitrate retention into a unified metric. Sensitivity analysis demonstrated that treatment rankings were largely unaffected by alternative weighting schemes, confirming the robustness of the CSI framework. The CSI identified mulch application, particularly the 4 cm mulch treatment, as the most effective management option based on overall sustainability performance. The CSI framework provides an integrated decision-support tool for evaluating coupled water–salt–nitrate interactions and improving water use efficiency and salinity management in arid agricultural systems. This study offers a novel integrated CSI-based framework for simultaneously quantifying hydrological and hydrochemical soil responses under mulch management in arid environments. Full article

Seashore paspalum (Paspalum vaginatum), a salinity-tolerant turfgrass, lacks well-characterized viral profiles. This study reports the discovery of a novel virus, tentatively named Paspalum latent virus (PaLV), representing a new taxon within the Alphaflexiviridae. Using high-throughput sequencing and RACE PCR, the 6995 nt genome was determined, revealing five open reading frames. Notably, PaLV lacks the AlkB domain and exhibits unique features, including overlapping start-stop codons (ORF4/ORF5) and a second in-frame AUG in the coat protein (CP) region. Phylogenetic analysis of the replicase placed PaLV in a distinct clade, separate from Potexvirus and Lolavirus. Despite low sequence identity, AlphaFold2 revealed conserved CP structural domains. Genetic analysis of 11 isolates showed low diversity and strong purifying selection. Pathogenicity assays through mechanical transmission demonstrated a broad but latent host range, including Zea mays and Sorghum spp. These findings suggest PaLV represents a novel species within a putatively new genus, Paspalovirus. Given its 90% incidence rate and latent profile, the RT-PCR assay developed here is vital for routine molecular diagnostics in turfgrass management and germplasm conservation. Full article

Global population growth and numerous anthropogenic activities are putting increasing pressure on island aquifers. This situation is exacerbated in popular tourist destinations where seasonal population fluctuations increase water consumption. Most island aquifers are threatened by overexploitation, contamination, and seawater intrusion (SWI), which threaten these resources’ sustainability. In this study, the vulnerability of the Bozcaada Island (Türkiye) to SWI during peak seasons (summer) was assessed using the GALDIT approach. The GALDIT index takes into account six key hydrogeological characteristics, including groundwater occurrence (G), which represents the type of aquifer (confined, unconfined, or semi-confined) and influences the interface between freshwater and saline water; aquifer hydraulic conductivity (A), where higher conductivity increases the risk of SWI and determines how easily water flows; groundwater level above mean sea level (L), which indicates hydraulic pressure against SWI; distance from the coast (D), which implies higher SWI risk when close to the coast; existing intrusion status (I), which takes into account current SWI detections based on the ratio of chloride ions to bicarbonate ions in a groundwater sample; and aquifer thickness (T). Bozcaada Island hosts a large number of tourists during the summer months, when agricultural production is at its peak, with a high demand for irrigation. This significantly increases the demand for groundwater and leads to saltwater intrusion. Based on the results of the GALDIT index, the island’s groundwater reserves are heavily used throughout the summer. The GALDIT index for the summer shows that this increased groundwater abstraction intensifies the SWI problem. In summer, the island is vulnerable with 6.11 km² of extremely high SWI, 7.88 km² of high SWI, 7.34 km² of moderate SWI, 7.40 km² of low SWI and 8.50 km² of very low SWI. This study emphasizes how urgently Bozcaada Island needs sustainable water management techniques. Full article

Soil quality is central to agricultural sustainability and food security, yet coastal agroecosystems are increasingly threatened by degradation from intensive practices and seawater intrusion. This study aimed to integrate soil quality index (SQI), statistical modeling, machine learning (ML), and decision analysis to assess and manage soil health in the Skhirat coastal plain of Morocco. A total of 30 topsoil samples were collected and analyzed for chemical and nutrient properties. Spatial interpolation revealed strong coast–inland gradients where EC ranged from 0.47 to 6.3 dS/m with the highest salinity in the south-western fringe, while CEC (8.4–39.7 cmol/kg) and OM (0.54–2.81%) peaked inland. Principal component analysis (PCA) explained 65.9% of total variance, with salinity drivers loading negatively against fertility indicators. Redundancy analysis (RDA) biplots highlighted antagonism between salinity and fertility axes. The PCA-minimum data set (MDS)-SQI integrated key indicators and ranged from 0.084 to 0.897 (mean 0.614), classifying 33% of sites as low quality. The ML model linear regression achieved the best performance (R² = 0.907). Multi-criteria decision analysis (MCDA) using TOPSIS and PROMETHEE II prioritized coastal sites with indices up to 0.882, and robust underweight sensitivity (Spearman ρ = 0.992). This integrated framework demonstrates that soil chemical monitoring, AI prediction, and MCDA can jointly deliver robust, site-specific management strategies for vulnerable coastal agroecosystems. Full article

Surface water-groundwater interaction zones are critical ecohydrological interfaces in arid regions, yet quantitative spatiotemporal patterns and soil-vegetation responses under coupled water-salt-heat gradients remain poorly documented. Based on a one-year monitoring period (August 2024–August 2025) at four sites along a river-to-desert transect (LW3: 25 m, LW2: 200 m, LW1: 300 m, LW4: 400 m from the Niya River) in the hyper-arid Tarim Basin, this study reveals the following quantitative patterns. Groundwater depth increased with distance from the river and followed an annual decrease-increase trend, with an anomalous shallow peak in March 2025 (−20 cm) linked to precipitation recharge. Soil temperature stability increased with depth: the 20 cm layer recorded the widest annual fluctuation (e.g., −1.5 °C to 24 °C at LW1), whereas the 80 cm layer varied only between approximately −0.2 °C and 28 °C. Proximity to the river dampened thermal extremes. Shallow soil moisture was highly dynamic (with a coefficient of variation [CV] reaching 40–50% at LW1 and LW4), while deeper layers remained stable; LW3 near the river stayed saturated year-round (CV = 0). Soil electrical conductivity (EC) decreased with distance from the river: LW3 exhibited the highest surface values (5000–16,000 μS cm⁻¹), whereas LW1 recorded the lowest (1000–2700 μS cm⁻¹). Vegetation performance was governed by coupled water-salt conditions rather than moisture alone: P. australis at LW1 achieved the tallest growth (>200 cm) and highest photosynthetic rates (20.25–37.38 μmol m⁻² s⁻¹), outperforming LW3 (104 cm, winter photosynthesis dropping to 2.01) and LW4 (~100 cm). Correlation analysis further showed strong vertical temperature coupling (r > 0.96 across all depths) and depth-stratified water-salt relationships (e.g., EC-volumetric water content r = 0.95 at 20 cm in LW4), reflecting spatial differentiation driven by freeze-thaw cycles, evaporative enrichment, and homogeneous silt-textured soils (54–96% fine fraction). These quantitative findings provide a detailed observational baseline for riparian ecohydrology in hyper-arid inland rivers and underscore that sustainable vegetation management requires balancing water availability against salinity stress. Full article

Saltwater intrusion (SI) threatens groundwater sustainability in nearshore regions, particularly in Bangladesh, where over-extraction and sea-level rise accelerate aquifer salinization. Accurate prediction of SI dynamics is therefore critical for effective groundwater management. This study developed and evaluated several deep learning and hybrid models, including CNN, DNN, LSTM, CNN–DNN, CNN–LSTM, DNN–LSTM, and CNN–DNN–LSTM, to predict SI in a nearshore aquifer system. Predictor–response datasets were generated using the three-dimensional density-dependent flow and solute transport model FEMWATER. This study presents the first comprehensive benchmarking of standalone and hybrid CNN–DNN–LSTM models for SI prediction in a Bangladesh nearshore aquifer, supported by CRITIC–EDAS-based model ranking. Model performance was assessed using RMSE, MAE, MAD, R, IOA, a-20, NRMSE, along with CRITIC weighting and EDAS ranking. Results indicate that hybrid models integrating LSTM outperformed standalone models. The CNN–LSTM model achieved the best performance at OW1 (RMSE = 1.57 mg/L, MAE = 1.26 mg/L, R = 0.99, IOA = 0.99). The DNN–LSTM model performed best at OW2 (RMSE = 2.87 mg/L, IOA = 0.98, R = 0.97) and OW3 (RMSE = 1.95 mg/L, IOA = 0.99, R = 0.99). In contrast, the DNN model showed poor performance, while the CNN model demonstrated moderate performance and the LSTM model underperformed. Overall, the hybrid CNN–LSTM and DNN–LSTM models demonstrated superior accuracy and robustness for reliable SI prediction and sustainable groundwater management. Full article

Transitional waters—such as estuaries, lagoons, deltas, and coastal wetlands—are dynamic environments where freshwater and seawater interact, forming highly productive and biologically diverse ecosystems. Shaped by temperature and salinity gradients, tidal influence, sediment transport, and nutrient-rich conditions, these habitats support diverse ecological functions. Their structural complexity—including seagrass beds, salt marshes, mudflats, and mangroves—provides essential habitats for many fish species. These areas are crucial for fish life cycles, serving as nurseries, spawning grounds, feeding zones, and refuges from predators. Many commercially important species depend on them during early life stages before moving offshore, making them vital for both commercial and recreational fisheries. Beyond food provision, they deliver key ecosystem services, including water purification, coastal protection, and carbon storage. Research on the fish community of the Ria Formosa lagoon in Portugal since the 1980s highlights long-term changes in the fish community and the dominant role of habitat structure and temporal dynamics. Subtidal seagrass beds support higher fish abundance and diversity than unvegetated areas, acting as key nursery habitats and provide important fish provisioning services. Seasonal variation is also central, driven by recruitment pulses of marine migrants in late winter–spring. Recent pressures on this system have been driven by human activity and environmental change. Seagrass loss reduces nursery and feeding areas, while pollution degrades water quality. Overfishing (including illegal fishing), recreational activities, and aquaculture expansion add stress. Climate warming and invasive species such as Caulerpa prolifera, further disrupt ecosystem balance and threaten biodiversity. Sustainable management—such as habitat restoration, protected areas, and integrated policies—is essential to preserve the ecological and economic value of this unique lagoon. Ongoing research, monitoring, habitat restoration, and stakeholder engagement remain critical for ensuring resilience. Full article

Introduction: The tub gurnard (Trigla lyra) is a demersal species of commercial interest whose long-term distributional dynamics remain poorly understood. Understanding spatial and temporal changes is essential for fisheries management and for assessing biogeographic shifts. Objective: To characterise the spatio-temporal distribution and persistence of T. lyra across Galician and Cantabrian Sea waters over a 33-year period (1993–2025) and to identify environmental and fishing drivers associated with observed changes. Methodology: We analysed data from the DEMERSALES bottom trawl survey series (1993–2025), for which the sampling design remained consistent throughout. Species distribution was modelled using a delta–GAM framework (presence–absence and positive values), complemented by a presence-only GAM fitted to Vessel Monitoring System (VMS) data; because these data were only available for 2009–2023, this model was restricted to that period for biological coherence. Environmental predictors included bathymetry, slope, sediment composition (organic matter, mud, fine and coarse sand), bottom temperature, and salinity. Spatial structure was assessed using aggregation curves, occupied area, centre of gravity, a Space Selectivity Index, and an Index of Persistence. Results: The occupied area increased from 45 to 963 km² (+2040%), accompanied by a sustained decline in the Space Selectivity Index and a westward shift of the distributional centroid (~20 km), indicating progressive range broadening. The frequency of occurrence rose from 4.5% in 1993 to 87.7% in 2025, reflecting a marked increase in spatial occupancy and encounter probability. Abundance increased sharply after 2015 (+47%), consistent with strong positive year effects in the GAM. Higher occurrence and densities were associated with muddy substrates, intermediate to high organic content, and depths of 100–300 m, matching the stable aggregation cores found along the shelf break. A reduction in trawling effort (−38% in mean intensity, −17% in swept area over 14 years) likely facilitated these trends. Conclusions: T. lyra expanded its distribution and shifted westward between 1993 and 2025, with persistent aggregation cores on the shelf break. No significant effect of temperature was found, suggesting that climate warming is not the primary driver; the expansion appears most plausibly to have been favoured by the decline in fishing pressure. Full article

Introduction: The Iberian killifish (Apricaphanius iberus), an endemic cyprinodontid of the Spanish Mediterranean coast, is a key conservation species due to its restricted distribution, high sensitivity to habitat alteration and invasive fish, and ecological role in saline wetlands. Classified as Endangered by national administration and listed in Annex II of the EU Habitats Directive, its populations have undergone severe declines across its native range. Coastal salt pans have become critical refuges for the persistence of this species, often supporting some of the highest population densities recorded. However, the conservation value of these anthropogenic systems strongly depends on hydrological management, which directly influences habitat stability and suitability. Objectives: This study aims to assess the long-term population responses of A. iberus under contrasting hydrological management regimes in coastal salt pans. Methodology: We analysed ten years of monitoring data across five salt pan circuits in the perimeter area of the Mar Menor coastal lagoon (SE Spain), covering a salinity gradient and three management regimes: economic exploitation (EE), preventive management (PM), and non-management (NM). Population metrics (occurrence, abundance and breeder proportion) were evaluated. Results: Population performance differed markedly among management regimes. EE circuits showed consistently high occurrence and abundance, including in hypersaline ponds, high breeder proportions, low interannual variability, and weak dependence on meteorological conditions and ephemeral prey. PM circuits displayed intermediate patterns. In contrast, NM circuits exhibited low occurrence and abundance, low breeder proportions, high temporal fluctuations, and strong dependence on meteorological variability. Conclusions: Hydrological management is a key determinant of A. iberus population stability in coastal salt pans. Maintaining or restoring traditional management practices enhances habitat suitability, buffers environmental variability, and supports conservation actions such as reintroduction. These findings highlight the critical role of managed anthropogenic wetlands as refuges for endangered fishes and provide a transferable framework for conservation under global change. Full article

Introduction: Elasmobranchs play a vital role in marine food webs through top-down control and the structuring of ecosystem stability, yet more than one-third of species face extinction. The Maldives, a recognised Indian Ocean hotspot for shark and batoid diversity, designated its EEZ as a shark sanctuary in 2010, but multispecies elasmobranch occurrence patterns and environmental drivers remain poorly characterised in Lhaviyani Atoll in the central Maldives, which hosts two Important Shark and Ray Areas (ISRAs). Recreational SCUBA networks can turn routine dive activity into long-term conservation evidence, already informing nearly 10% of the western Indian Ocean ISRAs. Objective: To characterise spatiotemporal patterns of elasmobranch assemblages in Lhaviyani Atoll (2017–2024), quantify how environmental and geomorphic drivers shape relative abundance, diversity, and hotspots, and provide evidence for targeted elasmobranch conservation. Methodology: A seven-year opportunistic dive-log dataset of 12,732 SCUBA surveys and 142,994 elasmobranch records across 94 dive sites was analysed. Effort-standardised relative abundance and community metrics (Shannon diversity, Pielou’s evenness) were modelled against sea surface temperature (SST), salinity, dissolved oxygen, chlorophyll-a, zonal current velocity, substrate type, and reef geomorphology using generalised additive models (GAMs). Spatial analyses identified persistent northern-rim aggregation areas aligned with ISRAs. Results: Twenty-eight species (14 sharks, 14 batoids) were recorded, including 23 threatened on the IUCN Red List (4 Critically Endangered, 12 Endangered, 7 Vulnerable). Relative abundance and diversity peaked during the late southwest monsoon (August–September) and declined during the northeast monsoon (December–March). After 2021, diversity and evenness increased while overall abundance declined. Relative abundance was primarily driven by SST, salinity, and current velocity; for sharks, dissolved oxygen and chlorophyll-a were additionally significant, whereas batoid abundance was driven mainly by temperature, oxygen, and current velocity. Four persistent hotspots along the northern atoll rim were identified, with sharks concentrated along exposed slopes and channels, and batoids distributed broadly within lagoonal habitats. Conclusions: Long-term citizen science dive-log monitoring is cost-effective for elasmobranch conservation in remote tropical seascapes. These results show how dive-industry partnerships can inform conservation governance over a decade after sanctuary designation, supporting targeted, habitat-focused management as shark and batoid conservation frameworks continue to evolve. Full article

This study evaluates the ecological impacts of seawater desalination discharge on coastal marine ecosystems through a sequential analytical framework linking systematic literature synthesis, field-monitoring evidence, spatial analysis, and predictive ecological modeling. The novelty of the study lies in combining multi-regional evidence from Mediterranean coastal zones, Persian Gulf waters, and Pacific coastal environments with threshold-based ecological risk assessment, thereby linking discharge-related environmental stressors with biological responses and ecosystem-function alterations. The systematic review first retained 750 studies published between 2004 and 2024 for qualitative synthesis. On this basis, 59 high-quality references with sufficient numerical information were selected for the main quantitative meta-analysis, while field-monitoring data were used to support the interpretation of distance-based discharge gradients. Spatial interpolation and hierarchical modeling were then applied to evaluate exposure–response patterns and ecological threshold behavior. The results showed that desalination facilities generated measurable ecological impacts mainly within 50–200 m of discharge points, with a critical transition distance of approximately 127 m where hypersaline conditions, typically 1.5–2.0 times ambient seawater levels, were associated with marked changes in marine community structure. Benthic assemblages showed taxon-specific responses, with mollusks and echinoderms exhibiting greater sensitivity than polychaetes and small crustaceans. Marine vegetation declined strongly under combined salinity, thermal, and chemical stress, while phosphonate-based antiscalants accumulated in filter-feeding organisms and produced bioaccumulation factors up to 42.1 times ambient levels. Ecosystem-function indicators, including microbial community composition and sediment organic matter processing, remained altered up to 300 m from discharge points, indicating that functional impacts may extend beyond the primary hypersaline plume. The predictive modeling framework further demonstrated that ecological risk decreased nonlinearly with distance and varied according to discharge intensity, local hydrodynamics, and biological sensitivity. These findings indicate that conventional uniform buffer-based assessment may underestimate the ecological footprint of desalination discharge. Sustainable desalination management should therefore adopt site-specific monitoring, species-sensitive protection thresholds, improved brine-management technologies, and adaptive mitigation strategies based on real-time environmental feedback. Full article

Rapid urbanization, climate change, and biodiversity loss are intensifying environmental pressures on arid coastal cities through extreme heat, water scarcity, salinity intrusion, and increasing flood risks. Despite substantial investment in urban green spaces across the Gulf region, many public parks provide limited ecological functionality and climate adaptation benefits. This study evaluated the ecological performance of three coastal parks in Muscat, Oman Sarooj Beach Park (23,080 m²), Ghubrah Beach Park (34,818 m²), and Al Athaiba Beach Park (17,370 m²), to identify opportunities for more resilient landscape design. The assessment revealed that although green space occupied 76.8–82% of park areas, tree canopy cover remained low (8–12%), limiting thermal comfort, habitat provision, and ecological performance. Based on these findings, a Functional and Climate-Responsive Planting Strategy (FCRPS) was developed by integrating the 10–20–30 biodiversity guideline with performance-based planting criteria tailored to arid and saline environments. The framework was applied to the proposed Majis Beach Ecological Park in Sohar, Oman, to demonstrate the implementation of ecological urbanism and nature-based solutions in a hyper-arid coastal environment. The resulting design incorporates biodiversity-enhancing planting, blue–green infrastructure, wetland restoration, and climate-responsive spatial planning. The study demonstrates how multifunctional landscapes can enhance biodiversity, improve thermal comfort, strengthen stormwater management, and support community well-being while providing a transferable framework for resilient public park design in arid coastal cities. Full article

Comprehensive biological and ecological data are essential for the appropriate stock management of Solenocera alticarinata Kubo, 1949. The lack of ecological knowledge on S. alticarinata, a species of potential economic value in the East China Sea, limits the development and implementation of appropriate fishery management measures such as minimum landing size and seasonal closure. Accordingly, we employed research vessels to characterize the seasonal spatial distribution patterns of S. alticarinata within the study area (26.5–35° N, 120–127° E) in 2018–2019. Our findings indicate that S. alticarinata can survive at a depth of 50–120 m and sea bottom salinity of 33–35. The highest biomass-based CPUE and greatest abundance of S. alticarinata were found during the summer and autumn, respectively. The seasonal ranking of the total catch per unit effort in number was as follows: autumn (1438.7 ind·h⁻¹) > summer and winter (1012.1–1078.2 ind·h⁻¹) > spring (287 ind·h⁻¹). In terms of mean average individual size, the order was summer > spring > autumn and winter. Overall, our findings provide a basis for developing management policies, and offer insights for designing fishery management and conservation strategies. Full article

The effects of climate change pose challenges to 21st-century society. Abiotic stresses such as salinity and drought represent a risk to biodiversity and the sustainability of urban and managed grasslands. In this study, we evaluated the interactive effects of mechanical defoliation (clipping), water deficit, and salinity under greenhouse conditions on several cultivars of two cool-season turfgrass species, Lolium perenne L. (‘Columbine’, ‘Allstarter’, ‘Esquire’) and Poa pratensis L. (‘Sombrero’, ‘Dakisha’, ‘Conni’). Water stress reduced relative leaf fresh and dry weight from approximately 66% to 28% and from 76% to 30%, respectively. Salinity induced moderate responses, mainly affecting root-related traits. Clipping reduced biomass, with relative leaf fresh and dry weight decreasing from 64% to 27% and from 86% to 28%, but it also stimulated compensatory responses, including increases in length increment from 0.17 to 0.29 cm day⁻¹, and in leaf and root water content from 63% to 67%. Lolium perenne showed greater root development than P. pratensis with higher root length (95% vs. 75%) and root surface area and volume (66% vs. 51%). Cultivar differences were evident, with ‘Columbine’ and ‘Allstarter’ showing greater stability, whereas ‘Dakisha’ was more sensitive. These findings highlight the importance of cultivar selection and clipping management under stress conditions. Full article