Search Results (648)

Since 2005, continuous research has been dedicated to unraveling the relationship between the sea lamprey (Petromyzon marinus) life cycle and fatty acid profiles. This mini review synthesizes the key findings of these investigations, transitioning from a chronological overview to a thematic approach focused on the utility of fatty acids as multifaceted biomarkers. Specifically, this work examines their application in identifying population and stock structures, decoding trophic ecology across ontogenetic stages, and tracking feeding strategies during the marine phase. Finally, the role of fatty acids in modulating cellular and physiological responses to environmental stressors—such as elevated salinity and pollutants—is addressed, highlighting the challenges lamprey juveniles overcome during their downstream trophic migration to the ocean. Full article

Located in the northern South China Sea (SCS), the Guangdong Sea areas exhibit a highly complex hydrodynamic structure driven by the combined effects of tides, monsoons, and offshore current systems, serving as a core region for China’s marine economy and offshore engineering. Although the Regional Ocean Modeling System (ROMS) is widely applied in current simulations, its accuracy is often constrained by the inadequate adaptability of its parameterization schemes to the regional environment. Furthermore, systematic parameter optimization tailored to this specific domain remains scarce. To address these limitations, this study conducts an observation-driven parameter optimization for surface current simulations in the western Guangdong Sea areas, aiming to enhance the reliability of hydrodynamic simulations and forecasting. A three-dimensional ROMS hydrodynamic model was employed to systematically design 18 physical parameterization experiments. The model’s performance was rigorously evaluated against 26 h continuous in situ current measurements from four observation stations, utilizing statistical metrics including the correlation coefficient (R), root mean square error (RMSE), Taylor diagrams, and the MMS standardized evaluation. The results indicate that the Mellor–Yamada vertical mixing scheme yields the optimal regional adaptability. For horizontal diffusion, the biharmonic scheme outperforms the Laplacian approach. Regarding bottom friction, the logarithmic formulation demonstrates superior accuracy compared to the quadratic and linear schemes, with the latter proven unsuitable for this region. A comprehensive evaluation identifies the ‘MY–Biharmonic–Logarithmic’ combination as the optimal parameterization configuration for the western Guangdong Sea areas. This study establishes an adaptable ROMS parameterization framework for the western Guangdong Sea areas and elucidates the influence mechanisms of key physical parameters on simulation outcomes. These findings not only provide high-precision hydrodynamic support for short-term pollutant dispersion forecasting, and disaster mitigation in this region but also offer valuable methodological references for numerical modeling in the broader SCS and analogous complex coastal environments. Full article

Microplastic pollution has become a global concern due to its widespread impacts on organisms and ecosystems. While there have been a few studies quantifying microplastics in inland areas of Puerto Rico, none, to our knowledge, have studied nearshore coastal surface waters. This study, therefore, presents the first assessment of microplastic concentrations and descriptions in the surface waters of La Parguera Natural Reserve, southwestern Puerto Rico. Using 333-micron plankton net trawls, we found low mean ± standard deviation microplastic concentrations of 0.02 ± 0.07 microplastic particles m⁻³ (95% confidence interval = 0.01 to 0.04 microplastic particles m⁻³). The most prevalent polymers were high-density polyethylene (48%) and polyethylene (32%), followed by polypropylene (11%) and polystyrene (7%). The most common colors were white (50%), blue (34%), black (8%), red (5%), and colorless (3%). Subsequently, the common structures found were fragments (78%), filaments (12%), films (8%), and fibers (2%). No clear coastal gradient or seasonal patterns were detected (p < 0.05), and mean concentrations were similar to previously surveyed oceanic waters from the Caribbean, suggesting coastal sources of marine microplastics were minimal compared to oceanic sources. This study provides a foundational understanding of microplastics in the coastal waters of La Parguera Natural Reserve and provides critical baseline data for detecting potential future changes in microplastic concentrations. Full article

Background: Oil spills have dramatically increased, causing significant damage and pollution to marine ecosystems. The entry of petroleum hydrocarbons into the ocean may lead to the occurrence of harmful algal blooms (HABs). The amino acid changes in harmful algae after oil spills remain unclear. Methods: In order to study the effect of oil spills on the amino acid mechanism of typical causative species, the composition and relative abundance of amino acids in Heterosigma akashiwo were investigated under different water accommodated fractions (WAFs) of 180# fuel oil. Results: Random forest prediction of polycyclic aromatic hydrocarbon toxicity to microalgae identified pyrene, benzo[k]fluoranthene, and fluoranthene as significant contributors. A total of 16 species of amino acids were detected in Heterosigma akashiwo, among which alanine, proline, aspartic acid, cysteine, lysine, and histidine were the predominant ones. As the concentration of the WAF increased, alanine abundance decreased significantly, indicating that the WAF disrupted the metabolic balance of alanine, with the degree of interference being positively correlated with exposure concentration. With the increase in culture time, the abundance of cysteine increased at 1%, 3%, and 5% WAFs, whereas the cysteine increased and then decreased at 7% and 10% WAFs. The abundance of aspartic acid and lysine showed no obvious pattern with culture time under WAF stress. Significant increases in the abundance of proline and histidine were observed in the WAF treatments. Conclusions: This study investigated the impact of oil spill pressure on the amino acid content of harmful algae, providing a scientific basis for understanding the potential impact of oil spills on the occurrence of HABs. Full article

As the core pillar of international trade, the global shipping industry has seen its carbon and pollutant emissions become a key challenge in global environmental governance. Statistics indicate that ship carbon emissions account for 3% of the world’s total anthropogenic CO₂ emissions, while contributing 20% of global NO_x and 12% of SO₂ emissions, posing a serious threat to coastal ecosystems and public health. In response to the International Maritime Organization (IMO) “Net Zero Framework” and national green shipping policies, the transformation of ship power systems toward low-carbon and zero-carbon operation has become an inevitable trend. This paper systematically reviews the research progress and application status of green energy materials for ships, focusing on the working principles, technical characteristics, and engineering application cases of solar photovoltaic (PV) materials, wind energy utilization technologies, fuel cell materials, and alternative clean energy fuels (e.g., liquefied natural gas (LNG), methanol, and hydrogen energy). It also discusses the integration mode and optimization strategy of multi-energy hybrid power systems. The research findings show that solar photovoltaic technology has achieved large-scale application in coastal ships; hydrogen fuel cells are suitable for long-range ocean navigation scenarios due to their high energy density; LNG and methanol have become the current mainstream alternative fuels, relying on mature infrastructure; and hybrid energy systems can significantly improve power supply reliability and emission reduction efficiency through multi-energy complementarity. Finally, aiming at the existing bottlenecks (e.g., cost, energy storage, and safety) of various technologies, future development directions are proposed. This study provides a reference for the technological breakthrough and engineering practice of green energy power systems for ships and contributes to the realization of the “carbon neutrality” goal in the global shipping industry. Full article

Large-scale disasters can result in chronic pollution of coastal environments with unanticipated and poorly quantified impacts, such as the reshaping of marine connectivity. A recent example is the collapse of the Fundão tailings dam in 2015, which released about 50 million m³ of mine waste into the Doce River, affecting one of Brazil’s largest estuarine–mangrove systems. Here, we combine a high-resolution CROCO hydrodynamic simulation with an individual-based Lagrangian model (Ichthyop) to track the dispersal of mangrove crab (Ucides cordatus) larvae from four estuaries along the southeastern Brazilian margin between 2022 and 2024. Trajectories crossing seasonal msPAF fields derived from in situ water-quality measurements were used to quantify larval exposure to contaminants from mine waste. These fields were based on measured concentrations of As, Ba, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, V, Zn, and Al. Results show that surface shelf flow and mesoscale activity in the vicinity of the Doce River mouth contribute to offshore export of larvae, while the reef-dominated Abrolhos shelf promotes retention. Interannual variability alternates between long-distance export and local retention, associated with regional climate variability. Larval mortality rates caused by offshore advection and lethal temperature are high (65–75%). In addition to these modeled mortality sources, surviving cohorts frequently crossed areas with elevated msPAF values during transport, indicating potential exposure to metal(loid) mixtures. This suggests that the regional connectivity of U. cordatus is under chronic stress that likely compromises the integrity and resilience of coastal populations, since southern estuaries depend strongly on northern larval sources. The integration of Lagrangian simulations with in situ contaminant monitoring and spatially explicit exposure metrics demonstrates that transport pathways regulate not only connectivity among estuaries but also the duration and intensity of larval exposure to pollutants. Full article

Wetland system design, management and modelling to support ecosystem services during climate change have been evaluated in this structured and critical review. The focus was on non-tidal and agriculture-linked wetlands in oceanic, temperate and boreal regions. After applying 54 search terms using Google Scholar, 229 references have been cited. The review indicates that local wetland improvements rarely have a measurable impact on the overall watershed. Water can be retained mostly successfully in the landscape for relatively low- and medium-level rainfall. For large and less frequent floods, the concept of Retaining Water in the Landscape rarely applies. The success of compensation schemes for European and United States American farmers to control flood retention depends on financial status, farm size, age and the contract term duration. Ecosystem disservices such as greenhouse gas and nutrient release from ditches should be counteracted by rewetting. Combined water level and nutrient management supports carbon sequestration and protects watercourses from eutrophication. Restored wetlands usually reduce diffuse pollution and enhance biodiversity. The conservation of existing natural wetlands compared to restoring former wetlands is normally more effective regarding carbon storage. The value of sustainably managed wetlands is up to 50 times higher than the mean wetland restoration costs. Full article

With the constant increase in the usage of plastic bottles in food production, ocean pollution has become a significant problem. The ability to organize in large fields is one of the critical problems nowadays, and their detection for further removal is a challenge. In this study, we propose the idea of equipping some of the plastic bottles on the production lines with simple radio-emitting equipment capable of signaling the presence of plastic bottle fields in the ocean to nearby vessels. The proposed idea is based on ultra-low-power energy harvesting that utilizes inherent wave energy. To assess the performance of the proposed framework, we developed a performance evaluation framework that captures the main specifics of the proposed detection system, including the probability of detecting at least one waste field and all waste fields in a given region. To showcase the potential of the proposed idea in this study, we also demonstrate that ultra-low-power harvesting using ocean waves is feasible. Our numerical results illustrate that for typical environmental parameters, the time range for detecting all waste fields in the area scales from 4–6 h to a few days at most. Additionally, the probability of detecting the presence of waste in the area is 2–3 times higher, potentially allowing for extremely fast detection and timely removal. We emphasize that the proposed system can be used to complement the currently available systems, not to replace them completely. Full article

Marine oil spills pose critical challenges to environmental sustainability and socioeconomic stability. Taking four pivotal cases as the entry point, this study uses comparative case analysis, semi-structured stakeholder interviews, policy analysis and international gap comparison to systematically analyze the evolution of marine oil spill governance in the Taiwan region of China over two decades, aiming to identify systemic gaps and propose actionable reforms. By integrating and explicitly detailing these multiple methodologies, this research not only identifies but also systematically examines the Taiwan region of China’s unique challenges as a non-UN-member entity navigating international conventions like the international convention for the prevention of pollution from ships, 1973, as modified by the protocol of 1978 relating thereto (MARPOL 73/78). Key findings reveal persistent issues in decision-support tools, fragmented inter-agency coordination, and legal inadequacies in compensation mechanisms. The study’s novelty lies in its rigorous synthesis of localized case-driven insights compared with global best practices, proposing a concrete, phased model for a unified task force and context-aware, data-driven contingency plans to enhance real-time response efficiency. It further advocates for pragmatic steps to align the Taiwan region of China’s Marine Pollution Control Act with international standards while critically addressing the transboundary collaboration barriers imposed by its political status, exploring potential pathways through sub-national and regional partnerships. Notably, the 2023 Angel Container case underscores the urgency of modernizing enforcement capacities and integrating advanced technologies. By bridging gaps in governance, legal accountability, and practical international engagement, this research not only advances the Taiwan region of China’s preparedness but also offers a nuanced and adaptable blueprint for coastal regions facing similar geopolitical and environmental constraints. Its recommendations hold significant implications for global marine pollution management, emphasizing the interplay of policy innovation, technological adoption, and pragmatic cross-jurisdictional cooperation. Full article

With the global increase in microplastic pollution, even environments considered pristine have shown signs of being affected by these contaminants. In this context, it becomes essential to conduct studies that identify and quantify the presence of microplastics in remote regions such as Antarctica. This continent is particularly relevant due to its low anthropogenic influence and its essential role in regulating planetary ecosystems and biodiversity. In this study, 49 Antarctic samples were analyzed using pretreatment techniques with NaCl and ZnCl₂ saline solutions, followed by fluorescence microscopy using Nile Red dye to estimate the microplastic abundance index. Both solutions showed good performance in the separation and identification of particles. Approximately 37% of the samples showed contamination by potential microplastics (PMPs), with a higher concentration of particles retained on paper filters and fibers observed in the supernatants. The results indicate that the presence of MPs in Antarctica is irregular and not ubiquitous, differing from other studies that suggest a wider distribution. It is speculated that the observed contamination results from oceanic transport from other regions of the planet and from sources associated with human activities on the Antarctic continent (e.g., tourism and research). Full article

Submesoscale oceanic eddies play a crucial role in ocean dynamics and climate systems, while Synthetic Aperture Radar (SAR) offers distinct advantages for observing these fine-scale phenomena; the advancement of automated detection algorithms is currently hindered by the lack of publicly available, high-quality benchmark datasets. To address this gap, this paper constructs a universal benchmark dataset for submesoscale eddies and presents an improved anchor-free object detection framework based on Fully Convolutional One-Stage (FCOS). We propose two key innovations: (1) a Deep Fusion Feature Pyramid Network (DF-FPN) that integrates adaptive multi-scale feature fusion directly into the pyramid construction process through deep fusion Adaptive Spatial Feature Fusion (ASFF) modules, enabling bidirectional feature enhancement and global context-aware fusion and (2) a Pixel-level Statistical Description Learning (PSDL) module that enhances feature representation by learning statistical descriptors across multiple scales. The DF-FPN replaces traditional staged optimization with an intrinsic deep fusion paradigm, significantly improving feature quality. Extensive experiments on our constructed dataset demonstrate that our method achieves 66.6% mAP, 91.3% AP₅₀, and 80.5% AP₇₅. These results represent a substantial improvement over the FCOS baseline and outperform other state-of-the-art detectors, providing a robust and efficient solution for operational submesoscale eddy monitoring in SAR imagery. Enhanced detection capacity of this kind offers a critical observational foundation for advancing research on upper-ocean nutrient transport, carbon cycle dynamics, and the dispersion of marine pollutants, thereby supporting broader environmental monitoring and climate-related objectives. Full article

Rivers are a key pathway for the transport of plastics into the ocean. Studies of plastic pollution in Arctic rivers remain limited due to the inaccessibility of sampling sites and work in extreme weather conditions. This work presents the results of a three-year (2019–2021) survey of floating large microplastics (0.5–5 mm) and meso/macroplastics (>5 mm) in the Northern Dvina River, an actively navigated river that drains a densely populated region into the White Sea. Sampling was conducted during the ice-free periods (May–October) along a ∼3.5 km transect using a Neuston net, providing a multi-year dataset spanning three ice-free seasons. A critical methodological advancement was the calculation of plastic river–sea flux using the discharge of the sampled surface layer (upper 20 cm), which constitutes only ∼3% of the river’s total discharge, rather than the total discharge itself. Observed microplastic concentrations (average 0.003 items ${\mathrm{m}}^{-3}$) were low compared to many European rivers, and lower than those reported in the adjacent Barents and Kara Seas. Microplastic abundance was significantly lower during the high-water season than during the low-water season, which resulted in practically no seasonal variability in microplastic fluxes from the river to the White Sea (average 0.3 items ${\mathrm{s}}^{-1}$). A notable finding was that in some cases, meso/macroplastics outnumbered microplastics by item count, underscoring the river’s role as a significant source of larger plastic debris. A geospatial assessment of Arctic rivers’ pollution potential was performed, using socio-economic indicators such as near-delta population density and port activity. This study identified the Northern Dvina River as a major contributor of microplastics among the Arctic rivers. Full article

Ocean Thermal Energy Conversion (OTEC) is characterized by its abundant reserves and pollution-free nature, enabling stable power generation around the clock. Since the power output of an OTEC system is significantly influenced by the energy available from cold and warm seawater, the accurate evaluation of the outlet temperature of the cold-water pipe (CWP) is crucial. To analyze the heat transfer performance of the CWP, this paper investigates the temperature field of the OTEC CWP and employs numerical simulation methods to conduct finite element analysis of the temperature field under different discharge conditions. The results indicate that during the pumping of deep-sea cold water through the CWP, heat is absorbed from the warmer upper seawater layers. When the pumping discharge rate is higher, the shorter fluid residence time due to higher flow velocity results in a lower outlet temperature. Compared to steel CWPs, high-density polyethylene (HDPE) is more suitable for OTEC systems due to its lower thermal conductivity and density. Full article

Marine-related activities contribute significantly to plastic pollution in oceans worldwide, particularly in regions located along international maritime routes such as Türkiye. The Dardanelles serves as a major maritime gateway connecting the Aegean Sea with both the Sea of Marmara and the Black Sea, enabling heavy vessel traffic that subsequently disperses plastic pollutants across large areas of the Mediterranean and beyond. Therefore, for the first time, this study applied material flow analysis to estimate potential sources and pathways of macro- and microplastics from 12 vessel categories, including fishing fleets, merchant ships, cruise liners, and military vessels in the Northern Aegean Sea. This approach provides insight into the range of sources and pathways, highlights priority areas for mitigation, and identifies additional knowledge gaps. Through material flow analysis–based estimations, general macro- and microplastic waste is found to be the largest contributor to marine plastic pollution, with an average of 14,965 tons/year, followed by antifouling particles at 5848.5 tons/year. Overall, this study presents a comprehensive evaluation of vessel-derived plastic pollution in a strategically significant maritime corridor and emphasizes its potential implications for the broader marine eco-system. Full article

Rivers are dynamic systems that flow from higher elevations to lowlands, eventually discharging into lakes, seas, or oceans, and play a key role in sustaining ecosystems and supporting human activities. River basin characterisation extends beyond the watercourse itself, encompassing land uses, tributaries and hydromorphological features that influence ecological processes. This review analyses three river basins in northern Portugal, Ave, Douro, and Vouga, using a holistic characterisation approach. These basins represent contrasting river systems in terms of size, hydrological regulation and dominant land uses, while simultaneously being subject to pressures frequently reported in many other river basins in Europe, and around the world. The analysis includes a general basin description, a hydromorphological assessment with emphasis on land use, and an evaluation of water ecological status, with particular focus on estuarine ecosystems. Water quality in the three basins has been strongly influenced by anthropogenic pressures, including industrial and agricultural activities, and wastewater discharges. Although the implementation of the European Water Framework Directive has led to improvements in recent decades, the degree of recovery varies among basins. Persistent challenges, such as nutrient concentrations, microbial contamination, and heavy metal pollution, highlight the need for integrated river basin management and improved monitoring strategies. This review provides transferable insights for the management of river basins facing similar environmental pressures. Full article