The Iraqi coast, particularly the Ras al Bisha region at the mouth of the Shatt al-Arab, is among the most sensitive regions to coastal changes due to the complex interplay between natural factors and human activities. This study analyzed spatial and temporal changes in the Ras al Bisha coastline over a 48-year period (1976, 1990, 2000, 2013, and 2024) using Landsat and the Digital Shoreline Analysis System (DSAS). Statistical indicators (NSM, SCE, LRR, and EPR) were calculated, spatial changes analyzed, and a decision matrix developed to assess the intensity of erosion-accretion, with projections for 2035 and 2045. Quantitative results revealed that coastal erosion dominated 75% of the sections, particularly in the central and western areas, with maximum erosion rates of −16.7 m/year (average: −5.56 m/year). Net accretion reached 1.84 km2 in the eastern region, while erosion reached 1.44 km2 in the western and central regions (1976–2024). Results revealed a clear temporal alternation between erosion-dominated periods (1976–1990 and 2000–2013) and accretion dominated periods (1990–2000 and 2013–2024). LULC classification achieved 92.5% accuracy (Kappa = 0.91). Coastal Vulnerability Index (CVI) analysis identified zones F, B, and D as high risk areas (CVI = 12.91–14.43) requiring urgent coastal management interventions. Future projections to 2045 indicated a baseline shoreline advance of +32.55 m, with continued eastward expansion of Ras al Bisha. The study’s novelty lies in integrating advanced DSAS analysis with comprehensive spatial analysis frameworks, decision matrix, and future projections, providing a dynamic and holistic assessment of coastal dynamics at Ras al Bisha. Unbalanced spatial distribution of erosion and accretion reflects complex interactions between natural factors (Shamal winds, ocean currents) and human activities (new Faw port, dredging). This study recommends adopting of an integrated coastal management system for Iraq, incorporating continuous remote sensing monitoring, advanced predictive modeling, and targeted engineering and environmental interventions to mitigate erosion risks and safeguard coastal infrastructure.
Microplastics, a persistent by-product of global plastic overuse and inadequate waste management, continue to accumulate across environmental compartments. As their large-scale removal remains technically unfeasible, fostering individual responsibility may be crucial to mitigating this pollution. This study assessed public knowledge and awareness regarding microplastic contamination among 407 respondents across various age groups (< 20, 20–40, 40–60, and > 60). The results indicate high awareness of microplastic transport into marine and freshwater systems, as well as its potential harmful effects on biota. However, recognition of atmospheric pollution and domestic sources remains limited. Notably, 91% of respondents acknowledged individual responsibility for reducing plastic waste. These findings underscore the need for targeted education and awareness-raising initiatives to foster behavioural change and safeguard the oceans.
Abstract The spatial and temporal variability of aerosol optical depth (AOD) over the Baltic Sea was analysed using two atmospheric reanalyses: MERRA-2 (1980–2023) and CAMSRA (2003–2023). The study examined total and speciated AOD at 550 nm – sulphate, organic, black carbon, sea salt, and dust – focusing on spatial patterns, long-term trends, seasonal cycles, and relationships with fire activity and the North Atlantic Oscillation (NAO). Both reanalyses show a south-to-north decrease in total AOD, with basin-mean values of 0.221 (1980–1999, MERRA-2), 0.135 (2003–2023, MERRA-2), and 0.116 (2003–2023, CAMSRA). The long-term trends are negative (−0.073 [62% confidence intervals: −0.111; −0.045] per decade, significant at a 90% confidence level, −0.006 [−0.009; −0.002] per decade, insignificant, and −0.016 [−0.021; −0.009] per decade, significant at a 90% confidence level, respectively), being strongest over the southern Baltic Sea and weaker in the north. The seasonal AOD cycle changed from a single spring maximum in the late 20th century to a dominant summer maximum after 2012. Fire activity shows its strongest correlation with total and black carbon AOD in spring, while the NAO index correlates positively with sea-salt AOD in winter and negatively in July. The greatest agreement between AOD characteristics derived from MERRA-2 and CAMSRA wasfound for total AOD and sea salt AOD.
Within the framework of the EuroGO-SHIP Project, an experiment on the long-term preservation of nutrients in seawater samples was conducted in May 2023 using high-salinity, low-nutrient continental shelf waters from the Gulf of Trieste. Sample comparison included filtered and non-filtered samples, preserved by both freezing and pasteurization techniques. The results indicated that neither of these methods is individually ideal for the long-term (6- and 12-month) preservation of seawater samples, although freezing is less affected by experimental biases than pasteurization. Syringe filtration (0.22 𝜇m pore size MCE filters) can cause the breakage of plankton cells and the release of nitrogen into the samples, whereas pasteurization can cause the remineralization of dissolved organic phosphorus and the release of phosphorus and silicate from marine particulate matter. Experimental results indicated that the best preservation method should be chosen depending on the biogeochemical characteristics of the marine system studied
Meroplankton, the pelagic larvae of benthic invertebrates, are an understudied component of zooplankton communities with particularly large knowledge gaps on interannual variation and long-term changes in meroplankton phenology. This study presents the first long-term assessment of meroplankton in the brackish southern Baltic Sea, spanning 17 years (2005–2021). Data from 11 stations across 33 cruises reveal significant temporal changes in community composition and biomass and encompass three distinct periods. Early in the time series, polychaete larvae typically dominated the spring meroplankton community, contributing most biomass and frequently persisting throughout the summer (June–August). This pattern became rare after 2014, when bivalve larvae dominated during summer. A spring community was present in multiple samples collected in June, only in years following cold winters. A second major shift occurred in 2019, characterized by a dramatic, order of magnitude increase in both meroplankton abundance and biomass, whereas the relative community composition remained largely unchanged. These transitions likely reflect rising water temperatures, and in particular winter sea surface temperatures above the temperature of maximum density for water within our study region. Our study links winter sea surface temperature and meroplankton phenology, with potentially strong implications for benthic recruitment and ecosystem functioning.
This study examined spatial and temporal variations in hydrography, nutrients, and phytoplankton along the Jeddah coast, Red Sea. Temperature ranged from 26.2 +/- 0.14 degrees C (February) to 33.4 +/- 0.17 degrees C (August), with minimal salinity changes. Nitrate, silicate, and SPM were elevated in the central region. Chlorophyll a and phytoplankton abundances peaked there, reaching 1.54 mg m-3 in October and 43,393 & times; 103 cells m-3 in July. Centric diatoms (Proboscia alata) dominated in summer, pennate diatoms (Lioloma elongatum) in May, and dinoflagellates in June (1246 & times; 103 cells m-3). Cyanophytes peaked in November. In total, 284 species, including 40 harmful taxa, were identified, mainly diatoms and dinoflagellates.
This study presents the first comprehensive investigation of the barrier layer (BL) in the Red Sea (RS) based on Argo float observations from 2012 to 2018, combined with sea level anomaly (SLA) data. The BL is defined as the layer between the temperature-based mixed layer (MLT) and the density-based mixed layer (MLD). The RS is divided into three regions-north (26 degrees N-22 degrees N), central (22 degrees N-18 degrees N), and south (18 degrees N-14 degrees N)-to analyze the spatial and temporal variability of the BL. The results show strong evidence of BL presence in all three regions during winter, with maximum thickness observed in January-February, decay by April, and almost no BL during summer. The BL is thickest in the north due to winter cooling and convection, with salinity stratification deepening the MLT below the MLD. It is more moderate and persistent in the central basin, and thinner and short-lived in the south. Buoyancy frequency and salinity analysis confirm that haline stratification stabilizes the water column and sustains the barrier layer. SLA data were used to examine the impact of mesoscale eddies, indicating that anticyclonic eddies (AEs) enhance BL thickness through convergence and downwelling, whereas cyclonic eddies (CEs) tend to erode the BL by shoaling the mixed layer. In the northern RS, unusual deep mixed layers sometimes occur within CEs, which is consistent with the convective overturning during winter. These findings provide the first description of BL characteristics, which improve our understanding of Red Sea upper ocean dynamics, vertical mixing, and climate interactions.
This study introduces a new framework for investigating tsunami propagation and its interaction with bathymetry by decomposing total energy into kinetic and potential components. Unlike conventional approaches based on wave amplitude or energy flux, this decomposition reveals local energy imbalances that arise when a tsunami interacts with variable bathymetry. These imbalances provide a new diagnostic tool for quantifying reflection and for distinguishing regions dominated by velocity (kinetic energy) or sea-level displacement (potential energy). The method is first tested in an idealized channel with a depth discontinuity. In addition to the expected incident, reflected, and transmitted waves, an imbalance between kinetic and potential energy emerges, with its magnitude controlled by the depth contrast. This imbalance forms the basis for defining a new reflection coefficient. The approach is then applied to the 2011 Japan T & omacr;hoku Tsunami. Results show that kinetic and potential energies remain in equilibrium during long-distance propagation but diverge near major bathymetric features such as Koko Guyot Seamount and Hess Rise, where the imbalance depends on the relative depth between the seafloor and the seamount summit. Finally, an elliptical seamount model illustrates the limitations of the method and clarifies the conditions under which energy imbalance is most relevant.
In this study, we aim to understand the influence of an underwater sill on the fate of suspended particulate material (SPM) discharged by a melting tidewater glacier in an Arctic glacial bay. We examined the potential significance of SPM retention for the bay's environment by analysing the fate of heavy metals introduced by glacier meltwater. Semi-enclosed bays with sills can not only limit water exchange but also act as effective traps for SPM and, consequently, for components, e.g., pollutants adsorbed onto these particles. Enhanced deposition of particulate pollutants can locally pose a threat to the ecosystem. We focus on Hansbukta, a glacial bay in Hornsund Fjord (Svalbard) that receives freshwater from the rapidly melting Hansbreen, a tidewater glacier. We analysed suspended particulate matter (SPM) concentrations and associated heavy metal content in six ablation seasons (2015-2020). Our results reveal seasonal variability in SPM and metal concentrations. In most months, over half of the analysed elements discharged with glacier meltwater remain in the bay. It was concluded that Hansbukta, which is isolated from the main fjord basin by an underwater sill, acts as a trap for metals and possibly other pollutants.
The Sunda Strait, a critical interoceanic conduit between the Pacific and Indian Oceans, exhibits a unique relationship between the skin SST (Ts) and the sea surface energy balance. This study aims to model the cool skin (OTc) and warm layer (OTw) using a coupled Regional Ocean Modeling System (ROMS) and the Simulating WAves Nearshore (SWAN) model. The focus is on analyzing the characteristics of OTc and OTw, quantifying the diurnal variability of the OTc, developing a correction of the bulk SST (Tb) to Ts, and analyzing the sea surface energy balance relative to Ts. Results show that the OTc layer contributes an average cooling of-0.2 degrees C that varies diurnally and increases with wind speed (U10) up to 8 m s-1 and stabilizes near-0.1 degrees C. A two-step correction based on U10 and the diurnal cycle was applied to minimize the discrepancy between Tb and Ts, successfully eliminating the combined influence of OTc and OTw (OTcw). Compared to other models, the proposed model shows a high correlation between OTcw and U10 in the Indian Ocean, Sunda Strait, and Java Sea of 0.69, 0.74, and 0.88, respectively. This study also shows that Ts has an ocean regimes and seasonal relationship context with U10, net shortwave flux (Rsw), net longwave flux (Rlw), net sensible heat flux (Rshf), and net latent heat flux (Rlhf). These findings establish Ts as a critical diagnostic parameter for understanding air-sea fluxes in tropical strait systems.
The hydrographic dynamics of the Malacca Strait Througflow (MST) during Indian Ocean Dipole (IOD) events remain poorly characterized, particularly for recent years. This study investigates the characteristics of water masses and circulation from 2020 to 2024 during different IOD phases. High-resolution ocean model data from Copernicus Marine Service (CMEMS) model outputs were examined using statistical analyses of temperature, salinity, and oxygen variability, complemented by volume transport and Lagrangian simulations to examine circulation pathways. The result revealed a strong north-south gradient in water-mass properties, where the northern region is significantly affected by Andaman Sea waters, which are higher in salinity and oxygen-depleted. The southern region receives water from the Java Sea and the South China Sea, which are warmer and less saline. The middle region serves as a mixing zone between the northern and southern water masses. Seasonal variations are most evident in surface waters, whereas deep-water characteristics remain stable throughout the seasons. Evidence indicates that different mixing processes occur in each region, affecting the distribution of water properties. IOD phases significantly modulate MST conditions. The positive IOD phases result in warmer temperatures, lower oxygen levels, and more stable salinity due to decreased freshwater input. In contrast, negative phases lead to cooler temperatures, higher oxygen concentrations, and lower salinity due to increased rainfall and runoff. Crucially, particle tracking revealed a bifurcated flow, with pathways towards both the Andaman Sea and the Java Sea, and volume transport increased by 7.02% in the south during positive IOD. These findings highlight the MST’s complex and regionally heterogeneous response to climate variability
The South Java Coastal Current (SJCC) transports warm water from the tropical Indian Ocean toward the southeast along the coastal areas of western Sumatra and southern Java. This study aims to reconstruct the SJCC and examine its seasonal and interannual variations during different phases of the Indian Ocean Dipole (IOD) and El Ni & ntilde;o-Southern Oscillation (ENSO) from 1993 to 2023. Surface ocean currents were examined using the Ocean Surface Current Analysis Real-time (OSCAR) dataset, along with sea level anomaly (SLA), ERA5 surface wind, Ni & ntilde;o 3.4, and Dipole Mode Index (DMI). Results reveal that, on the intraseasonal timescale, the SJCC exhibits a dominant periodicity of about 76 days. In general, the eastward surface currents along the southern waters of Java are formed throughout the year. From June to September, the eastward surface currents are usually absent under normal conditions but appear during negative IOD and La Ni & ntilde;a events, driven by wind mechanisms and Kelvin wave activity. Conversely, during positive IOD and El Ni & ntilde;o events, the eastward surface currents weaken significantly or are suppressed, especially from October to January. The influence of IOD events on the eastward surface currents is stronger than that of ENSO. The variability of the eastward surface currents is affected not only by seasonal monsoon winds but also by large-scale ocean-atmosphere interactions and the movement of equatorial Kelvin waves. Understanding these processes is essential for more accurate prediction of regional circulation, heat transfer, and climate variability in the southeastern tropical Indian Ocean.
Magnetic fields generated by submarine cables and marine renewable energy devices may negatively affect organisms living nearby. At the same time, the number of projects related to the strategic integration of low-trophic aquaculture within offshore wind farms is increasing. As there is a complete lack of information on the effects of magnetic fields macroalgae, in our study, we investigated the effects of an electromagnetic field (EMF; 50 Hz, 1 mT) on the basic indicators of macroalgal functioning in two Baltic species of commercial value, Fucus vesiculosus and Furcellaria lumbricalis. EMF had a limited effect on the growth of both species. No changes were observed in nutrient uptake rates, water content, or organic matter content.
This paper deals with an important coastal engineering problem of defining proper seabed saturation conditions, which have a significant influence on the pore-fluid compressibility and the wave-induced cyclic response of poro-elastic seabed sediments. A unique in-situ measuring campaign was conducted in the tidal zone of the northern beach of Norderney, off the North Sea coast of Germany, where 186 sandy seabed samples were taken underwater. Based on the laboratory measurements, a set of calculated saturation degrees was statistically analysed. Both the histogram and the normal Q-Q plot, as well as the Shapiro-Wilk normality test, confirmed the validity of the assumption of the normal probability distribution for the variability of the degree of saturation. The mean degree of saturation of the top layer of the seabed, (S) over bar (r)= 0.973, constitutes the main output of the study, whereas the uncertainty propagation analysis enabled to define the possible range of variation, which is 0.962 <= (S) over bar <= 0.986. It should be clearly emphasised that a proper assessment of the seabed saturation conditions is very important, mainly due to the correctness of the description of the wave-induced pore-fluid pressure field used in more detailed analyses of the pore-fluid pressure gradients and the liquefaction potential of the seabed, which have a direct impact on phenomena such as sand transport on beaches, seabed erosion, and stability of coastal structures (e.g. breakwaters and submarine buried pipelines).
We study the dynamics of barotropic currents at semidiurnal and diurnal frequency bands in the inner shelf and surf zone off the west coast of India using moored velocity observations. In both the Inner shelf and the Surf zone, the observed current exhibits significant semidiurnal and diurnal energy. The hourly climatology of residual currents exhibits a strong diurnal variability in the barotropic currents in the both regions. A 2D hydrodynamic model, Delft3d, was implemented, and sensitivity experiments were performed to understand the role of wind and wave in the tidal and diurnal variability of barotropic currents in the region. Surf zone barotropic currents in diurnal band are strongly modulated by the winds. However, wind has minimal influence on the barotropic current in the inner shelf. Sensitivity experiments with and without waves show that, apart from wind, wave parameters have significant influence on the diurnal variability of surf zone currents. Analysis further confirms that diurnal currents in the surf zone are primarily wind-driven, while inner shelf currents are mostly tide-dominated. Overall, this study underscores the necessity of incorporating wind, wave, and tidal forcing to realistically simulate nearshore currents in the inner shelf and surf zone along the west coast of India.
This study presents a comprehensive analysis of Fluorescent (FDOM) and Chromophoric (CDOM) Dissolved Organic Matter in the southern Baltic Sea, enhancing our understanding of its composition, sources, and dynamics in a semi-enclosed marine system. The Baltic Sea's unique hydrography and strong freshwater inflow served as a natural laboratory for investigating interactions between terrestrial and marine Dissolved Organic Matter (DOM). We examined spatial and seasonal variations of CDOM and FDOM, using absorption and fluorescence spectroscopy combined with parallel factor analysis (PARAFAC). Six fluorophore groups (C1-C6) were identified, with humic-like components (C1-C3, C5) of terrestrial and marine origin dominating the FDOM composition. Protein-like components (C4, C6) were more prominent in Open Waters (OW), particularly in late summer and fall. Humic-like fluorescence intensity (I-tot) contributed 61-96% to total fluorescence (I-tot).The total fluorescence intensity was much higher in the Gulf and Coastal Waters, GCW than in the Open Waters (OW) of the Baltic Sea. The vertical distributions of FDOM varied by region. In the Open Baltic Deep Waters (OBDW) the highest I-h values were observed near the bottom, likely resulting from diffusion of DOM from sediments, and the lowest at the surface. In the Gulf of Gdansk Deep Waters (GGDW) I-h was the lowest in the Baltic Sea Winter Water (BSWW). I-p was the highest at the surface and the weakest at the bottom, in both areas. This study offers new insight into the spatial, seasonal, and vertical behavior of FDOM and underscores its sensitivity to environmental conditions.
Record or near-record high or low river flows are more often observed in different regions of the world. A thriving society must understand the magnitude of these changes in the future, mitigate their negative impacts, and be prepared to live in a different world. That is why qualified, constantly updated scientific projections of future changes are essential. Neither Lithuania nor the other Baltic countries have yet assessed runoff changes according to the latest climate change projection tools outlined in the IPCC 6th AR on climate change. In this study, the HBV model was used to project potential changes in river runoff. The ranking procedure was developed and used to select the best-fit GCMs that most accurately reproduced the climate conditions of Lithuania. Due to the anticipated changes in climatic factors affecting the studied rivers, the average annual discharge is projected to decrease by 12 to 42%, depending on the hydrological region (i.e., the conditions of river runoff formation) and the selected future period. High flows (Q5) are likely to decline very similarly to the annual ones, while low flows (Q95) are expected to decrease by approximately two-thirds compared to the reference period. An uncertainty analysis of the projections revealed that GCMs contributed up to two-thirds of the total uncertainty in the final results.
The Atlantic wedge clam or common rangia, Rangia cuneata, was reported in the Gda & nacute;sk Basin (southern Baltic Sea) around 2010. In the Gulf of Gda & nacute;sk, outside the Vistula Lagoon, specimens of the common rangia were collected for the first time in 2014. This paper reports on the spread of the species in the coastal waters of the Gulf of Gda & nacute;sk following its arrival.
Identifying and collecting accumulated contaminants is crucial for environmental protection in enclosed bodies of water, such as the Caspian Sea. As the world's largest landlocked water body, its limited exchange with open seas and oceans hinders self-purification. This research maps contaminant accumulation at the mouth of the Sefidrud River on the southern coast of the Caspian Sea using vessel-mounted ADCP, CTD, and water sampling data. Field measurements were conducted in two distinct seasons at different stations and transects ranging from 2-15 m in depth. The results show that the contaminants accumulated in the core of sub-mesoscale eddies. These surface sub-mesoscale eddies trap nutrient-rich freshwater discharging from the river, creating distinct hydrographic cores with significantly elevated nutrient levels, as well as different temperature and salinity compared to the surrounding waters.
The non-indigenous Boccardiella ligerica is a polychaete introduced to the Baltic Sea. Although the species has been recorded in the Baltic Sea since the 1960s, this is the first time we have reported the repeated occurrence of B. ligerica in various new locations along the Polish coast. Between 2009 and 2018, the species was recorded in the Vistula Lagoon, the Gulf of Gda & nacute;sk and Puck Bay. Samples of the species were collected from hard substrates and bottom sediments at depths ranging from approximately 1.0 m to 13.3 m using a range of sampling gear, including van Veen and Ekman-Birge grab samplers, a HAPS corer and settlement plates, as well as by scraping vertical surfaces during diving. The highest densities, reaching up to 1689 ind. m-2 and 414 ind. m-2, were recorded in the Gulf of Gda & nacute;sk and the Vistula Lagoon, respectively. The lowest abundance (13 ind. m-2) of this polychaete was recorded in Puck Bay. The results obtained contribute to the understanding of the dynamics of this non-indigenous species in the brackish environments of the Baltic Sea. They provide a basis for further research on this species, considering that B. ligerica may play an important role in food webs, as it feeds on phytoplankton and detritus, and serves as food for small fish and invertebrates.
