Journal of Marine Science and Engineering

21 pages, 903 KiB

Open AccessArticle

A Novel Approach for the Systematic Evaluation and Optimization of Performance and Emissions in Hybrid Electric Propulsion Systems

by Jayoung Jung, Hyeonmin Jeon, Heemoon Kim and SeongWan Kim

J. Mar. Sci. Eng. 2025, 13(2), 328; https://doi.org/10.3390/jmse13020328 (registering DOI) - 11 Feb 2025

Abstract

In the maritime industry, the adoption of hybrid electric propulsion systems aims to enhance energy efficiency and environmental sustainability. However, this study originates from the fundamental question: ‘Are hybrid systems truly environmentally friendly?’ Ensuring optimal system performance requires accurate load analysis and an [...] Read more.

In the maritime industry, the adoption of hybrid electric propulsion systems aims to enhance energy efficiency and environmental sustainability. However, this study originates from the fundamental question: ‘Are hybrid systems truly environmentally friendly?’ Ensuring optimal system performance requires accurate load analysis and an effective energy management system. Existing studies have limitations in addressing real-time load variability, long-term load patterns, and scalability across different operational conditions. To address these, this study proposes a standard load analyzer based on main engine power output data to conduct performance analysis. Using MATLAB/Simulink simulations and Excel VBA-based methods, the system evaluates key performance factors under various operational load conditions. Cross-validation between MATLAB and Excel ensured high accuracy, with a relative error rate below 0.01%. The results showed consistent performance indicators, offering reliable insights across vessel types and scenarios. The system’s lightweight design and rapid data acquisition enable effective energy management optimization. However, it has limitations in performing detailed analyses for life cycle assessment, operating expenditures, and capital expenditures. Future advancements in data consolidation and analytical methods will help the tool evolve into a comprehensive tool for multi-dimensional performance evaluation, addressing economic, environmental, and technical aspects. Full article

(This article belongs to the Section Ocean Engineering)

22 pages, 41809 KiB

Open AccessArticle

Real-Time Mooring Tension Prediction for Semi-Submersible Aquaculture Platforms by an EEMD-TCN-SA Neural Network Approach

by Changfeng Liu, Yu Xin, Yu Zhang, Yutong Yang, Lei Sun and Changping Chen

J. Mar. Sci. Eng. 2025, 13(2), 327; https://doi.org/10.3390/jmse13020327 (registering DOI) - 11 Feb 2025

Abstract

Precise prediction of mooring tension is essential for the safety and operational efficiency of semi-submersible aquaculture platforms. Traditional numerical methods struggle with real-time performance due to the nonlinear and dynamic characteristics of environmental loads. This study proposes a novel neural network approach to [...] Read more.

Precise prediction of mooring tension is essential for the safety and operational efficiency of semi-submersible aquaculture platforms. Traditional numerical methods struggle with real-time performance due to the nonlinear and dynamic characteristics of environmental loads. This study proposes a novel neural network approach to enhance real-time forecasting of mooring line responses, combining Ensemble Empirical Mode Decomposition (EEMD), Temporal Convolutional Networks (TCNs), and a Self-Attention (SA) mechanism. The training dataset encompasses time-domain analysis results, including mooring tensions, motion responses, and total structural forces. Firstly, Pearson Correlation Analysis (PCA) is utilized to assess the linear relationships among the hydrodynamic variables. Subsequently, EEMD is applied to decompose the mooring tension data, which is then combined with the highly correlated variables to form the input dataset. Finally, the TCN model is trained to predict the time series, while an SA mechanism is integrated to weigh the significance of different moments within the sequence, thereby further enhancing prediction accuracy. The results demonstrate that the evaluation metrics of the EEMD-TCN-SA model outperform those of other neural network models, effectively predicting mooring tension for semi-submersible platforms and significantly reducing prediction errors. Full article

(This article belongs to the Section Coastal Engineering)

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18 pages, 4091 KiB

Open AccessArticle

Buoy and Winch Collaborative Control System Based on Deep Reinforcement Learning

by Yang Gu, Jianjun Ni, Zaiming Geng, Bing Zhao and Haowen Yang

J. Mar. Sci. Eng. 2025, 13(2), 326; https://doi.org/10.3390/jmse13020326 (registering DOI) - 11 Feb 2025

Viewed by 106

Abstract

The improved control performance of the buoy and winch collaborative control system can enhance the stability of the connection between underwater robots and ground industrial control equipment. To overcome the challenge of mathematical modeling of this control system, this research introduces reinforcement learning [...] Read more.

The improved control performance of the buoy and winch collaborative control system can enhance the stability of the connection between underwater robots and ground industrial control equipment. To overcome the challenge of mathematical modeling of this control system, this research introduces reinforcement learning and transformer models in the design process. The main contributions include the development of two simulation environments for training DRL agents, designing a reward function to guide the exploration process, proposing a buoy control algorithm based on the discrete soft actor-critic (SAC) algorithm, and proposing a winch cable length prediction algorithm based on a lightweight transformer model. The experiment results demonstrated significant improvements in rewards diagrams, buoy control trajectories, and winch model performance, showcasing the effectiveness of our proposed system. The average error of the buoy tracking trajectories induced by different policies trained in the two environments is less than 0.05, and the evaluation error of the behavior cloning lightweight transformer model is less than 0.03. Full article

(This article belongs to the Special Issue Navigation and Detection Fusion for Autonomous Underwater Vehicles)

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34 pages, 4722 KiB

Open AccessArticle

Enhancement Strategy for Port Resilience: Shipping Route Optimization Methods Based on Network Characteristics of Ports

by Xiang Yuan and Xinhao He

J. Mar. Sci. Eng. 2025, 13(2), 325; https://doi.org/10.3390/jmse13020325 (registering DOI) - 10 Feb 2025

Viewed by 210

Abstract

Ports and their affiliated shipping routes are fundamental to the maritime logistics system, crucial for global trade. However, they face risks from natural disasters and human-induced crises. Enhancing port resilience, the ability to quickly recover and maintain operations during disruptions is vital for [...] Read more.

Ports and their affiliated shipping routes are fundamental to the maritime logistics system, crucial for global trade. However, they face risks from natural disasters and human-induced crises. Enhancing port resilience, the ability to quickly recover and maintain operations during disruptions is vital for a robust maritime network. This study focuses on enhancing port resilience by improving the shipping route network, using an innovative link-prediction-based approach. Initially, a multi-dimensional resilience analysis is conducted to identify key low-resilience and bottleneck ports, guiding targeted network optimizations. Then, a novel link prediction algorithm is applied to find potential new shipping connections, significantly enhancing network efficiency, robustness, and port resilience. The optimized network effectively improves the connectivity of critical low-resilience ports with central hub ports and bottleneck ports with surrounding ones. Route diversification mitigates risks and strengthens overall resilience. Key low-resilience ports and bottleneck ports are reduced by an average of 20% and 25%. Finally, practical strategies are proposed. Low-resilience ports should establish direct connections with major hubs, and regional sub-networks can offer support. For bottleneck ports, additional secondary and short distance links should be added to transform them into more integrated hubs, enhancing the network’s robustness. These strategies improve the network’s operational capacity during crises, ensuring efficient cargo flow. Full article

(This article belongs to the Special Issue Maritime Transport and Port Management)

5 pages, 194 KiB

Open AccessEditorial

New Challenges in Marine Aquaculture Research

by Ana Catarina Matias and Carlos Andrade

J. Mar. Sci. Eng. 2025, 13(2), 324; https://doi.org/10.3390/jmse13020324 (registering DOI) - 10 Feb 2025

Viewed by 156

Abstract

Marine aquaculture has witnessed remarkable growth in recent decades, contributing significantly to global food security and economic development [...] Full article

(This article belongs to the Special Issue New Challenges in Marine Aquaculture Research)

33 pages, 10667 KiB

Open AccessArticle

CFD Design Optimisation for the Hydrodynamic Performance of the Novel Fin-Ring Horizontal Axis Hydrokinetic Turbine

by Mahmoud I. Ibrahim, María J. Legaz, Adel A. Banawan and Tamer M. Ahmed

J. Mar. Sci. Eng. 2025, 13(2), 323; https://doi.org/10.3390/jmse13020323 (registering DOI) - 10 Feb 2025

Viewed by 230

Abstract

In this paper, the aim is to optimise the hydrodynamic performance of the novel fin-ring horizontal axis hydrokinetic turbine (HAHK). The original unique fin-ring turbine is an unconventional marine current turbine that comprises seven concentric rings with 88 connecting cambered fins and a [...] Read more.

In this paper, the aim is to optimise the hydrodynamic performance of the novel fin-ring horizontal axis hydrokinetic turbine (HAHK). The original unique fin-ring turbine is an unconventional marine current turbine that comprises seven concentric rings with 88 connecting cambered fins and a solid centre hub. To begin with, the hydrodynamic performance of the benchmark turbine is evaluated using CFD simulations and is validated against sea-test data available in the literature. Subsequently, three of the turbine design parameters, namely, the fins’ pitch angle, the fins’ camber length, and the fins’ aspect ratio, are optimised for maximum power generation. Further test simulations illustrated the existence of a laminar region of flow in the turbine flow field. The K-kL-ω transition-sensitive turbulence model is adopted to capture the influence of transition on the flow field with results compared against those of the fully turbulent K-ε turbulence model. A final fine-tuning in the turbine design is carried out by increasing the number of fins per ring in the outermost rings to further maximise the generated power. The turbine hydrodynamic performance is assessed by comparison against other conventional hydrokinetic turbines available in the literature. Very satisfactory results are obtained with an increase of about 35% in the turbine-generated C_P as compared to that of the benchmark turbine. The turbine performance compares very well with other conventional turbines, especially in terms of higher peak C_P values, wider operating TSR range, and less sensitivity to variations in the inflow current speeds. Full article

(This article belongs to the Special Issue Development and Utilization of Offshore Renewable Energy)

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24 pages, 14530 KiB

Open AccessArticle

Reconstruction of the Cenozoic Deformation of the Yinggehai Basin and Beibu Gulf Basin, South China Sea

by Jiaxiao Zhao, Chenghao Liu, Jingjin Zhao and Qingjun Xu

J. Mar. Sci. Eng. 2025, 13(2), 322; https://doi.org/10.3390/jmse13020322 - 10 Feb 2025

Viewed by 332

Abstract

This study employs structural information and stratigraphic lithology as constraints to conduct balanced restoration on seismic profiles from the Yinggehai Basin (YGB) and the Beibu Gulf Basin (BGB). The reconstruction indicates that the evolutionary periods of the YGB can be classified into five [...] Read more.

This study employs structural information and stratigraphic lithology as constraints to conduct balanced restoration on seismic profiles from the Yinggehai Basin (YGB) and the Beibu Gulf Basin (BGB). The reconstruction indicates that the evolutionary periods of the YGB can be classified into five distinct stages: rift stage (56–36 Ma), fault depression stage (36–23 Ma), depression stage (23–15.5 Ma), inversion stage (15.5–5.3 Ma), and depression stage (5.3–0 Ma). In contrast, the evolutionary stages of the BGB are categorized into four stages: rift stage (66–56 Ma), fault depression stage (40–32 Ma), fault-depression transition stage (32–23 Ma), and depression stage (23–0 Ma). The BGB did not experience a tectonic inversion phase similar to that of the YGB, but both have undergone a fault depression stage under the same tectonic background. The rotational extrusion of the Indochina block has accelerated the opening of the rift basins along the northern and western margins of the South China Sea (SCS). The dual subduction processes of the Proto-SCS has led to the opening of the SCS Basin. Within the BGB, a significant increase in the dilatation strain rate (DSR) can be observed over a large area. The transition in the strike-slip nature of the Red River Fault Zone is evidenced by tectonic inversion in the stratigraphy. The tectonic mechanism of the YGB is primarily controlled by the convergence of the India-Eurasia plate, while the evolution of the BGB is governed by the subduction of the Pacific plate, the convergence of the India-Eurasia plate, and the dual subduction of the Proto-SCS. Full article

(This article belongs to the Section Geological Oceanography)

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Graphical abstract

28 pages, 9375 KiB

Open AccessReview

Contemporary Issues and Advancements in Coastal Eolianite Research

by David H. Backus

J. Mar. Sci. Eng. 2025, 13(2), 321; https://doi.org/10.3390/jmse13020321 - 10 Feb 2025

Viewed by 304

Abstract

This review of eolianite research—following a comprehensive overview earlier this century—looks at several areas of overlapping research in coastal eolianite deposition, including the following: tectonic setting; carbonate–sediment type and source areas (carbonate factories); the relationship between relative sea-level change and eolianite deposition; and [...] Read more.

This review of eolianite research—following a comprehensive overview earlier this century—looks at several areas of overlapping research in coastal eolianite deposition, including the following: tectonic setting; carbonate–sediment type and source areas (carbonate factories); the relationship between relative sea-level change and eolianite deposition; and the evolution of depositional models. Several locations are highlighted in order to emphasize the variety in the eolianite depositional record based on more recent research. In particular, a historical review of eolianite depositional models developed over the last 100-plus years indicates that purely high-stand models of the last century—developed on steep-sided carbonate platforms—do not adequately reflect the complex depositional histories found on other coastal shelves. More recent depositional models emphasize high-stand carbonate production followed by the mobilization of shelf sediments during subsequent relative drops in sea level. Full article

(This article belongs to the Special Issue Feature Review Papers in Geological Oceanography)

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6 pages, 179 KiB

Open AccessEditorial

Hydrodynamic Circulation Modelling in the Marine Environment

by Yannis Androulidakis and Christos Makris

J. Mar. Sci. Eng. 2025, 13(2), 320; https://doi.org/10.3390/jmse13020320 - 10 Feb 2025

Viewed by 263

Abstract

Modelling hydrodynamic circulation in the marine environment is one of the most challenging topics in the marine sciences [...] Full article

(This article belongs to the Special Issue Hydrodynamic Circulation Modelling in the Marine Environment)

24 pages, 4374 KiB

Open AccessArticle

The Effects of Anthropic Structures on Coastline Morphology: A Case Study from the Málaga Coast (Spain)

by Rosa Molina, Giorgio Manno, Antonio Contreras de Villar, Bismarck Jigena-Antelo, Juan José Muñoz-Pérez, J. Andrew G. Cooper, Enzo Pranzini and Giorgio Anfuso

J. Mar. Sci. Eng. 2025, 13(2), 319; https://doi.org/10.3390/jmse13020319 (registering DOI) - 9 Feb 2025

Viewed by 435

Abstract

The Málaga coast, in the south of Spain, is a densely populated tourist destination where ports, marinas and coastal protection structures of various typologies (e.g., groins, breakwaters, revetments) and shapes (e.g., “Y”, “L”, etc., shaped groins) have been emplaced. Such structures have modified [...] Read more.

The Málaga coast, in the south of Spain, is a densely populated tourist destination where ports, marinas and coastal protection structures of various typologies (e.g., groins, breakwaters, revetments) and shapes (e.g., “Y”, “L”, etc., shaped groins) have been emplaced. Such structures have modified the long- and cross-shore sediment transport and produced changes in beach morphology and the evolution of nearby areas. To characterize the changes related to shore-normal structures, beach erosion/accretion areas close to coastal anthropic structures were measured using a sequence of aerial orthophotos between 1956 and 2019, and the potential littoral sediment transport for the two main littoral transport directions was determined by means of the CMS (Coastal Modeling System). Available data on wave propagation and coastal sediment transport reflect the complex dynamics of the study area, often characterized by the coexistence of opposing longshore transport directions. Accretion was observed on both sides of ports in all studied periods and on both main coastal orientations. Groins and groups of groins presented mixed results that reflect the heterogeneity of the study area; in certain sectors where the wave regime is bidirectional, changes in shoreline trend were found from one period to another. The study cases described in this paper emphasize the difficulties in finding clear spatial and temporal trends in the artificially induced erosion/accretion patterns recorded along a heavily modified shoreline. Full article

(This article belongs to the Section Coastal Engineering)

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22 pages, 5742 KiB

Open AccessArticle

Preliminary Biological Assessments of Some Algae Basis Biomaterials

by Toader Marian, Nicoleta Radu, Mariana Voicescu, Cristina Lavinia Nistor, Lucia Camelia Pirvu, Mirela Mihaila and Marinela Bostan

J. Mar. Sci. Eng. 2025, 13(2), 318; https://doi.org/10.3390/jmse13020318 - 9 Feb 2025

Viewed by 449

Abstract

Four types of algae—Porphyra umbilicalis, Undaria pinnatifida, Cystoseira barbata, and Chlorella sp.—were used to obtain crude bioproducts enriched in polysaccharides (four bioproducts) and to create formulations enriched with gold cations (four bioproducts). The bioproducts obtained through aqueous extraction from [...] Read more.

Four types of algae—Porphyra umbilicalis, Undaria pinnatifida, Cystoseira barbata, and Chlorella sp.—were used to obtain crude bioproducts enriched in polysaccharides (four bioproducts) and to create formulations enriched with gold cations (four bioproducts). The bioproducts obtained through aqueous extraction from Cystoseira barbata exhibited significant antioxidant activities and a total polyphenol content of (714.17 ± 1.26) mg GAE/L. In the bioproducts derived from the aqueous extract of Porphyra umbilicalis and Undaria pinnatifida, combined with gold ions, gold nanoparticles with sizes of less than 34 nm were formed. In vitro tests performed on the Caco-2 tumour cell line with each of the eight bioproducts, after 24 h of exposure, showed that the crude bioproducts containing polysaccharides derived from Porphyra umbilicalis, Undaria pinnatifida, and Chlorella sp. exhibited cytotoxicity against the Caco-2 cell line. In the case of the HepG2 cell line, after 24 h of exposure, the tests indicated that only the crude polysaccharides derived from Cystoseira barbata exhibited cytotoxic effects. These results indicate the protective effect of the algal polysaccharides against the tumourigenesis processes that may occur in the human digestive system. Regarding the bioproducts containing gold, no cytotoxic effect was observed. However, in the case of the two algal bioproducts containing gold nanoparticles with a size of less than 34 nm, they may represent potential raw materials for electrochemical sensors. Full article

(This article belongs to the Special Issue Marine Microorganisms and Their Biomolecules: Biodiversity, Physiological Adaptation and Biotechnological Applications)

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34 pages, 10936 KiB

Open AccessArticle

Enhanced Minimum Spanning Tree Optimization for Air-Lifted Artificial Upwelling Pipeline Network

by Junjie Zhang, Wei Fan, Yonggang Zhao, Zhiyu Zou, Mengjie Qu and Ying Chen

J. Mar. Sci. Eng. 2025, 13(2), 317; https://doi.org/10.3390/jmse13020317 - 9 Feb 2025

Viewed by 344

Abstract

Artificial upwelling (AU), a geoengineering technique aimed at transporting nutrient-enriched deep-sea water to the sunlit surface layers through artificial systems, is increasingly recognized as a promising approach to enhance oceanic fertility and stimulate primary marine productivity, thereby bolstering the ocean capacity for carbon [...] Read more.

Artificial upwelling (AU), a geoengineering technique aimed at transporting nutrient-enriched deep-sea water to the sunlit surface layers through artificial systems, is increasingly recognized as a promising approach to enhance oceanic fertility and stimulate primary marine productivity, thereby bolstering the ocean capacity for carbon sequestration. Several air-lifted AU systems have been implemented in countries such as Norway and China. However, research on the optimization of the air injection pipeline network (AIPN)—a critical component of the air-lifted AU system—remains limited. This paper introduces a refined minimum spanning tree algorithm to propose a novel approach for optimizing the AIPN. Furthermore, the bubble-entrained plume loss rate (N_BEP) is developed as a model to assess the efficiency of air-lifted AU systems, which is applied to three case studies involving air-lifted AU systems of varying scales. The findings indicate that the enhanced minimum spanning tree algorithm outperforms the conventional Prim’s algorithm, leading to an average 87% reduction in N_BEP of the optimized AIPN, compared to the AIPN of previous air-lifted AU systems while improving system stability. Consequently, the proposed optimization method for AIPN offers valuable scientific and practical insights for the engineering design of the air-lifted AU systems across diverse scales, offering transformative potential for large-scale carbon sequestration and marine productivity enhancement. Full article

(This article belongs to the Section Ocean Engineering)

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18 pages, 11076 KiB

Open AccessArticle

Influence of Load Variation on the Flow Field and Stability of the Francis Turbine

by Shenhui Li, Jiayang Pang, Chengmei Dan, Wenping Xiang, Xutao Yi and Xiaobing Liu

J. Mar. Sci. Eng. 2025, 13(2), 316; https://doi.org/10.3390/jmse13020316 - 9 Feb 2025

Viewed by 277

Abstract

With the development of a power system predominantly reliant on new energy sources, turbine generator sets are increasingly required to operate under wide load conditions, resulting in numerous unstable flow phenomena and substantial economic losses for power stations. This study employs the Shear [...] Read more.

With the development of a power system predominantly reliant on new energy sources, turbine generator sets are increasingly required to operate under wide load conditions, resulting in numerous unstable flow phenomena and substantial economic losses for power stations. This study employs the Shear Stress Transport (SST) k-ω turbulence model to combine numerical simulations with experimental methods. It calculates the guide vane opening at the rated head of a Francis turbine and examines the internal flow field characteristics and pressure pulsations under various operating conditions. The findings indicate that the entropy production ratio in the draft tube is the highest among all load conditions, ranging from about 72.7% to 95.9%. Energy dissipation in the vaneless zone and the runner increases with greater opening. At 45% and 100% load conditions, the draft tube is mainly influenced by dynamic and static interference, single and double frequencies induced by runner rotation, and low-frequency fluctuations of the vortex and. Under 60% load conditions, pressure fluctuations in the draft tube are primarily caused by the eccentric vortex band, characterized by higher intensity and a frequency of 0.2 f_n. Numerical results closely align with experimental observations. The findings provide essential guidance for ensuring the stable operation of power plant units. Full article

(This article belongs to the Section Ocean Engineering)

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17 pages, 4185 KiB

Open AccessArticle

The Spatial Distribution Dynamics of Shark Bycatch by the Longline Fishery in the Western and Central Pacific Ocean

by Shengyao Xia, Jiaqi Wang, Xiaodi Gao, Yiwei Yang and Heyang Huang

J. Mar. Sci. Eng. 2025, 13(2), 315; https://doi.org/10.3390/jmse13020315 - 8 Feb 2025

Viewed by 336

Abstract

Shark bycatch represents a substantial issue in the management of oceanic fisheries. Utilizing data on shark bycatch from the longline fishery, as released by the Western and Central Pacific Fisheries Commission, this study applied the boosted regression tree model to examine the impact [...] Read more.

Shark bycatch represents a substantial issue in the management of oceanic fisheries. Utilizing data on shark bycatch from the longline fishery, as released by the Western and Central Pacific Fisheries Commission, this study applied the boosted regression tree model to examine the impact of environmental factors on the bycatch per unit effort (BPUE) of key bycatch species, as well as to predict the spatial distribution dynamics of both BPUE and bycatch risk (BR). The findings emphasize that the oxygen concentration, sea surface temperature, and chlorophyll-a concentration are paramount to sharks’ BPUE. Furthermore, the study compared the variations in environmental preferences across diverse shark species, pinpointing key environmental attributes defining the ecological niches of distinct shark populations. The spatial predictions identified the hotspots of BPUE and BR for the bigeye thresher shark (Alopias superciliosus), longfin mako (Isurus paucus), silky shark (Carcharhinus falciformis), and oceanic whitetip shark (Carcharhinus longimanus) in tropical latitudes (10° S to 15° N), and for the blue shark (Prionace glauca) and shortfin mako (Isurus oxyrinchus) in temperate zones (south of 30° S or north of 30° N). The geometric center analysis indicated that all shark species exhibited large annual fluctuations in BPUE and BR, and most populations displayed significant shifting trends. Several grids (5° × 5°) were identified as high-risk areas due to their considerable contribution to bycatch. Furthermore, the geometric centers of BR were observed to shift eastward towards equatorial waters, compared to the geometric centers of BPUE. This underscores the necessity of considering factors beyond BPUE when identifying critical areas for the implementation of area-specific bycatch mitigation measures. The insights derived from this study can enhance and support the development and enforcement of targeted area-based fishery management initiatives. Full article

(This article belongs to the Section Marine Ecology)

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13 pages, 1481 KiB

Open AccessArticle

Bacterial Carbon Demand and Primary Production in a Posidonia oceanica System: A Re-Evaluation of Carbon Fluxes

by Branko Velimirov and Markus Weinbauer

J. Mar. Sci. Eng. 2025, 13(2), 314; https://doi.org/10.3390/jmse13020314 - 8 Feb 2025

Viewed by 268

Abstract

An earlier ecosystemic study on carbon balance calculations of a Posidonia oceanica system in the Bay of Calvi [Corsica, France], indicated that the bacterial carbon demand [BCD] between May and October [Temp > 18 °C] in the seagrass meadow could not be sustained [...] Read more.

An earlier ecosystemic study on carbon balance calculations of a Posidonia oceanica system in the Bay of Calvi [Corsica, France], indicated that the bacterial carbon demand [BCD] between May and October [Temp > 18 °C] in the seagrass meadow could not be sustained by net leaf production of P. oceanica and its epiphytes [NPP]. Hence, the system was clearly heterotrophic as only one autotrophic region was recorded, namely the depth range from 0–10 m. Already published data on the production of algal macrophytes and Cymodocea nodosa meadows and their mapping in the Bay of Calvi allowed a re-evaluation of the carbon budgets for each specific depth range. It was shown that C. nodosa could contribute significantly to covering the bacterial carbon demand of the P. oceanica system and that a positive carbon balance could be obtained for the seagrass meadow due to this carbon input when the temperature was higher than 18 °C, even though the depth ranges between 21–30 m and 31–38 m were negative. The overall trend indicates that the system cannot rely on the phytoplanktonic production of the water column, as BCD is higher than phytoplanktonic carbon production. When integrating BCD and net primary production [NPP] of the water column in summer we noticed a lack of some 97.6 to 104.3 tons of carbon which is not covered by the seagrasses leaf production and the algal macrophytes. The obtained data indicate clearly that other carbon carbon-producing compartments like the microphytobenthos, the NPP of rhizome epiphytes, and the detrital carbon import into the Bay of Calvi need to be investigated. Full article

(This article belongs to the Section Marine Ecology)

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11 pages, 1737 KiB

Open AccessTechnical Note

A New Expression for a Goda Type Breaker Index Formula in Spectral Wave Models

by Zereng Chen, Qinghe Zhang and Yang Nie

J. Mar. Sci. Eng. 2025, 13(2), 313; https://doi.org/10.3390/jmse13020313 - 7 Feb 2025

Viewed by 291

Abstract

The breaker index in contemporary spectral wave models is a vital parameter in studying depth-induced wave breaking, which is an important mechanism in coastal engineering. In the previous study, the authors modified a Goda type breaker index formula and parameterized it in a [...] Read more.

The breaker index in contemporary spectral wave models is a vital parameter in studying depth-induced wave breaking, which is an important mechanism in coastal engineering. In the previous study, the authors modified a Goda type breaker index formula and parameterized it in a spectral wave model. Although this parameterization model can accurately simulate nearshore wave height variations under various laboratory and field conditions, the computation of deep-water wave conditions in the formula necessitates reverse calculation based on the incident waves, thus limiting its applicability. To solve this problem, a new expression for this Goda type breaker index is rederived, enabling its applicability to simulate breaking waves caused by variable wave conditions on open boundaries and wind field inputs in the whole computational region. The model’s capability to simulate wave heights in laboratory and field experiments is comparable to that of the original formula. Full article

(This article belongs to the Section Ocean Engineering)

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25 pages, 4924 KiB

Open AccessArticle

Thresholding Dolphin Whistles Based on Signal Correlation and Impulsive Noise Features Under Stationary Wavelet Transform

by Xiang Zhou, Ru Wu, Wen Chen, Meiling Dai, Peibin Zhu and Xiaomei Xu

J. Mar. Sci. Eng. 2025, 13(2), 312; https://doi.org/10.3390/jmse13020312 - 7 Feb 2025

Viewed by 541

Abstract

The time–frequency characteristics of dolphin whistle signals under diverse ecological conditions and during environmental changes are key research topics that focus on the adaptive and response mechanisms of dolphins to the marine environment. To enhance the quality and utilization of passive acoustic monitoring [...] Read more.

The time–frequency characteristics of dolphin whistle signals under diverse ecological conditions and during environmental changes are key research topics that focus on the adaptive and response mechanisms of dolphins to the marine environment. To enhance the quality and utilization of passive acoustic monitoring (PAM) recorded dolphin whistles, the challenges faced by current wavelet thresholding methods in achieving precise threshold denoising under low signal-to-noise ratio (SNR) are confronted. This paper presents a thresholding denoising method based on stationary wavelet transform (SWT), utilizing suppression impulsive and autocorrelation function (SI-ACF) to select precise thresholds. This method introduces a denoising metric

ρ

, based on the correlation of whistle signals, which facilitates precise threshold estimation under low SNR without requiring prior information. Additionally, it exploits the high amplitude and broadband characteristics of impulsive noise, and utilizes the multi-resolution information of the wavelet domain to remove impulsive noise through a multi-level sliding window approach. The SI-ACF method was validated using both simulated and real whistle datasets. Simulated signals were employed to evaluate the method’s denoising performance under three types of typical underwater noise. Real whistles were used to confirm its applicability in real scenarios. The test results show the SI-ACF method effectively eliminates noise, improves whistle signal spectrogram visualization, and enhances the accuracy of automated whistle detection, highlighting its potential for whistle signal preprocessing under low SNR. Full article

(This article belongs to the Section Ocean Engineering)

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18 pages, 4135 KiB

Open AccessArticle

Assessing the Impacts of the Israeli–Palestinian Conflict on Global Sea Transportation: From the View of Mass Tanker Trajectories

by Bing Zhang, Xiaohui Chen, Haiyan Liu, Lin Ye, Ran Zhang and Yunpeng Zhao

J. Mar. Sci. Eng. 2025, 13(2), 311; https://doi.org/10.3390/jmse13020311 - 7 Feb 2025

Viewed by 300

Abstract

Sea transportation plays a vital role in global trade, and studying the impact of emergencies on global sea transportation is essential to ensure the stability of trade. At present, the conflict between Palestine and Israel has attracted extensive attention worldwide. However, there is [...] Read more.

Sea transportation plays a vital role in global trade, and studying the impact of emergencies on global sea transportation is essential to ensure the stability of trade. At present, the conflict between Palestine and Israel has attracted extensive attention worldwide. However, there is a lack of specific research on the impact of conflict on shipping, particularly on global shipping costs. By using the global vessel trajectory data of tankers from the Automatic Identification System (AIS) and taking the global sea transportation of large tankers as an example, this paper quantifies and visualizes the changes in global sea transportation before and after conflicts from a data-driven perspective. Firstly, the complete vessel trajectory, as well as the port of departure and the port of destination are extracted. Then, from the perspective of shipping cost and vessel traffic flow, we evaluate the vessel traffic flow changes caused by the conflict by using the route distance to replace the shipping costs and quantify the cost increase for the relevant countries caused by the vessel detour based on the shipping cost increment index. The research results show that after the outbreak of the conflict, the number of vessels passing through the Red Sea area has decreased significantly. About 3.1% of global vessels were affected, with global sea transportation costs of large tankers increasing by about 0.0825%. This study takes the Israeli–Palestinian conflict as an example and analyzes the impact of emergencies on the global sea transportation situation of tankers based on AIS data. The research results reveal the characteristics of international shipping to a certain extent and provide guidance for global sea transportation route planning. Full article

(This article belongs to the Special Issue Risk Assessment in Maritime Transportation)

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27 pages, 9529 KiB

Open AccessArticle

Hydrodynamics Model Identification and Model-Based Control Application of a New Type of AUV

by Lunyang Lin, Yuxiang Chen, Hong Xiong, Chunliang Yu, Hong Zhu, Yiyang Xing and Guodong Zheng

J. Mar. Sci. Eng. 2025, 13(2), 310; https://doi.org/10.3390/jmse13020310 - 7 Feb 2025

Viewed by 362

Abstract

The hydrodynamic coefficients of underwater robots can be used to evaluate their maneuverability and motion stability and to design motion controllers, thereby reducing experimental time and costs. In this paper, an Autonomous Underwater Vehicle (AUV) with a negative-lift profile is designed. The spatially [...] Read more.

The hydrodynamic coefficients of underwater robots can be used to evaluate their maneuverability and motion stability and to design motion controllers, thereby reducing experimental time and costs. In this paper, an Autonomous Underwater Vehicle (AUV) with a negative-lift profile is designed. The spatially constrained motion method, combined with neural networks, is utilized to identify all the hydrodynamic coefficients in the standard hydrodynamic equations of the AUV. Subsequently, based on the goodness-of-fit, the significance of the hydrodynamic coefficients is evaluated to yield a simplified hydrodynamic equation. Given the cost constraints, it was not feasible to obtain precise experimental data on hydrodynamic coefficients to validate the accuracy of the CFD calculation method. Therefore, the hydrodynamic coefficients were used to construct a dynamic model for the AUV, and an MPC controller was designed based on this model. Finally, simulations and pool tests were conducted on the AUV, and a comparative analysis of the simulation results with the pool test results revealed that although there were certain errors in the calculation of the hydrodynamic coefficients, the controller constructed within this margin of error was still capable of effectively controlling the AUV. This fully demonstrates the feasibility and applicability of using CFD methods to calculate hydrodynamic coefficients and establishing model predictive control methods based on these coefficients in practical applications. Full article

(This article belongs to the Special Issue Marine Technology: Latest Advancements and Prospects)

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19 pages, 32782 KiB

Open AccessArticle

Artificial Fish Reef Site Evaluation Based on Multi-Source High-Resolution Acoustic Images

by Fangqi Wang, Yikai Feng, Senbo Liu, Yilan Chen and Jisheng Ding

J. Mar. Sci. Eng. 2025, 13(2), 309; https://doi.org/10.3390/jmse13020309 - 7 Feb 2025

Viewed by 383

Abstract

Marine geophysical and geological investigations are crucial for evaluating the construction suitability of artificial fish reefs (AFRs). Key factors such as seabed topography, geomorphology, sub-bottom structure, and sediment type significantly influence AFR design and site selection. Challenges such as material sinking, sediment instability, [...] Read more.

Marine geophysical and geological investigations are crucial for evaluating the construction suitability of artificial fish reefs (AFRs). Key factors such as seabed topography, geomorphology, sub-bottom structure, and sediment type significantly influence AFR design and site selection. Challenges such as material sinking, sediment instability, and scouring effects should be critically considered and addressed in the construction of AFR, particularly in areas with soft mud or dynamic environments. In this study, detailed investigations were conducted approximately seven months after the deployment of reef materials in the AFR experimental zones around Xiaoguan Island, located in the western South Yellow Sea, China. Based on morphological factors, using data from multibeam echosounders and side-scan sonar, the study area was divided into three geomorphic zones, namely, the tidal flat (TF), underwater erosion-accumulation slope (UEABS), and inclined erosion-accumulation shelf plain (IEASP) zones. The focus of this study was on the UEABS and IEASP experimental zones, where reef materials (concrete or stone blocks) were deployed seven months earlier. The comprehensive interpretation results of multi-source high-resolution acoustic images showed that the average settlement of individual reefs in the UEABS experimental zone was 0.49 m, and their surrounding seabed experienced little to no scouring. This suggested the formation of an effective range and height, making the zone suitable for AFR construction. However, in the IEASP experimental zone, the seabed sediment consisted of soft mud, causing the reef materials to sink into the seabed after deployment, preventing the formation of an effective range and height, and rendering the area unsuitable for AFR construction. These findings provided valuable scientific guidance for AFR construction in the study area and other similar coastal regions. Full article

(This article belongs to the Section Coastal Engineering)

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17 pages, 39227 KiB

Open AccessArticle

Submarine Slides and Their Influence on Gas Hydrate and Shallow Gas in the Pearl River Mouth Basin

by Jiapeng Jin, Jinzi Hu, Lixia Li, Jie Li, Zhenyu Zhu, Xiujuan Wang, Jilin Zhou and Wenlong Wang

J. Mar. Sci. Eng. 2025, 13(2), 308; https://doi.org/10.3390/jmse13020308 - 7 Feb 2025

Viewed by 362

Abstract

Submarine slides, gas hydrates, shallow gas, and volcanoes considered to be potential geohazards have been well delineated using three-dimensional (3D) seismic data and well log data in the Pearl River Mouth Basin, South China Sea. Seismic characteristics, distribution maps, and controlling factors of [...] Read more.

Submarine slides, gas hydrates, shallow gas, and volcanoes considered to be potential geohazards have been well delineated using three-dimensional (3D) seismic data and well log data in the Pearl River Mouth Basin, South China Sea. Seismic characteristics, distribution maps, and controlling factors of these geohazards have been well analyzed showing the influence of regional tectonics and sedimentary processes. Recently, shallow gas and gas hydrates are confirmed by drilling expeditions, which are considered important unconventional resources. Moreover, the mapped features of various geohazards show the spatial overlays and that they are connected each other. To delineate well the relationships between gas hydrates, shallow gas, and the potential geological features such as submarine slides, gas chimneys, faults, and volcanoes, the seismic attributes and interpretations are displayed using 3D seismic data to show the interplay between them. Gas hydrates and shallow gas occur and are widely distributed above sills, volcanoes, gas chimneys, and faults within the submarine slides and migrating canyon because large amount of hydrocarbon gas can migrate from the deep layer to the shallow layer along different pathways. This study aims to show the correlation among various geological bodies and their effects on shallow gas and gas hydrate distributions. Full article

(This article belongs to the Special Issue Marine Geohazards: Characterization to Prediction)

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18 pages, 20102 KiB

Open AccessArticle

Time-Domain Simulation of Coupled Motions for Five Fishing Vessels Moored Side-by-Side in a Harbor

by Xuran Men, Jinlong He, Bo Jiao, Guibing Zhu, Haihua Lin and Hongyuan Sun

J. Mar. Sci. Eng. 2025, 13(2), 307; https://doi.org/10.3390/jmse13020307 - 7 Feb 2025

Viewed by 352

Abstract

With the rapid development and accelerated utilization of marine resources, multi-body floating systems have become extensively used in practical applications. This study examines the coupled motions of a side-by-side anchoring system for five fishing vessels in a harbor using ANSYS-AQWA. The system is [...] Read more.

With the rapid development and accelerated utilization of marine resources, multi-body floating systems have become extensively used in practical applications. This study examines the coupled motions of a side-by-side anchoring system for five fishing vessels in a harbor using ANSYS-AQWA. The system is connected by hawsers and equipped with fenders to reduce collisions between the vessels. It is designed to operate in the sheltered wind-wave combined environment within Ningbo Zhoushan Port, China. Considering the diverse types and quantities of fishing vessels in the anchorage area, this paper proposes a mixed arrangement of three large-scale fishing vessels in the middle and two small-scale vessels on both sides. The time-domain analysis is performed on this system under the combined effects of wind and waves, calculating the motion responses of the five fishing vessels along with the mechanical loads at the hawsers, fenders, and moorings. The results indicate that the maximum loads on these mechanical components remain well within the safe working limits, ensuring reliable operation. In addition, the impact of varying wind-wave angles on the coupled motions of the fishing vessel system are studied. As the wind-wave angle increases, the surge motion of the fishing vessels gradually decreases, while the sway motion intensifies. The forces on the hawsers, fenders, and mooring system exhibit distinct characteristics at different angles. Full article

(This article belongs to the Section Ocean Engineering)

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17 pages, 4941 KiB

Open AccessArticle

Underwater Target Localization Method Based on Uniform Linear Electrode Array

by Wenjing Shang, Feixiang Gao, Jiahui Liu, Yunhe Pang, Sergey V. Volvenko, Vladimir M. Olshanskiy and Yidong Xu

J. Mar. Sci. Eng. 2025, 13(2), 306; https://doi.org/10.3390/jmse13020306 - 6 Feb 2025

Viewed by 474

Abstract

The underwater electric field signal can be excited by underwater vehicles, such as the shaft-rate electric field and the corrosion electric field. The electric field signature of each vehicle exhibits significant differences in time and frequency domain, which can be exploited to determine [...] Read more.

The underwater electric field signal can be excited by underwater vehicles, such as the shaft-rate electric field and the corrosion electric field. The electric field signature of each vehicle exhibits significant differences in time and frequency domain, which can be exploited to determine target positions. In this paper, a novel passive localization method for underwater targets is presented, leveraging a uniform linear electrode array (ULEA). The ULEA manifold along the axial direction is derived from the electric field propagation in an infinite lossy medium, which provides the nonlinear mapping relationship between the target position and the voltage data acquired by the ULEA. In order to locate the targets, the multiple signal classification (MUSIC) algorithm is applied. Then, capitalizing on the rotational invariance of matrix operations and exploiting the symmetry inherent in the ULEA, we streamline the six-dimensional spatial spectral scanning onto a two-dimensional plane, providing azimuth and distance information for the targets. This method significantly reduces computational overhead. To validate the efficacy of our proposed method, we devise a localization system and conduct a simulation environment to estimate targets. Results show that our method achieves satisfactory direction and reliable distance estimations, even in scenarios with low signal-to-noise ratios. Full article

(This article belongs to the Special Issue Intelligent Measurement and Control System of Marine Robots)

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31 pages, 1106 KiB

Open AccessArticle

Comparative Analysis of the Alternative Energy: Case of Reducing GHG Emissions of Estonian Pilot Fleet

by Riina Otsason, Andres Laasma, Yiǧit Gülmez, Jonne Kotta and Ulla Tapaninen

J. Mar. Sci. Eng. 2025, 13(2), 305; https://doi.org/10.3390/jmse13020305 - 6 Feb 2025

Viewed by 443

Abstract

The FuelEU Maritime Regulation, part of the European Union’s (EU’s) Fit for 55 initiative, aims to achieve significant reductions in greenhouse gas (GHG) emissions within the maritime sector. This study assesses the feasibility of alternative fuels for the Estonian pilot fleet using a [...] Read more.

The FuelEU Maritime Regulation, part of the European Union’s (EU’s) Fit for 55 initiative, aims to achieve significant reductions in greenhouse gas (GHG) emissions within the maritime sector. This study assesses the feasibility of alternative fuels for the Estonian pilot fleet using a Well-to-Wake (WtW) life cycle assessment (LCA) methodology. Operational data from 18 vessels, sourced from the Estonian State Fleet’s records, were analyzed, including technical specifications, fuel consumption patterns, and operational scenarios. The study focused on marine diesel oil (MDO), biomethane, hydrogen, biodiesel, ammonia, and hydrotreated vegetable oil (HVO), each presenting distinct trade-offs. Biomethane achieved a 59% GHG emissions reduction but required a volumetric storage capacity up to 353% higher compared to MDO. Biodiesel reduced GHG emissions by 41.2%, offering moderate compatibility with existing systems while requiring up to 23% larger storage volumes. HVO demonstrated a 43.6% emissions reduction with seamless integration into existing marine engines. Ammonia showed strong potential for long-term decarbonization, but its adoption is hindered by low energy density and complex storage requirements. This research underscores the importance of a holistic evaluation of alternative fuels, taking into account technical, economic, and environmental factors specific to regional and operational contexts. The findings offer a quantitative basis for policymakers and maritime stakeholders to develop effective decarbonization strategies for the Baltic Sea region. Full article

(This article belongs to the Section Marine Energy)

19 pages, 8500 KiB

Open AccessArticle

Preliminary Investigation of the Spatial-Temporal Characteristics and Vertical Dynamics of Internal Solitary Waves in the South China Sea from SWOT Data

by Zhikuan Pan, Zhenhe Zhai, Qi Li, Qianqian Li, Lin Wu and Lifeng Bao

J. Mar. Sci. Eng. 2025, 13(2), 304; https://doi.org/10.3390/jmse13020304 - 6 Feb 2025

Viewed by 458

Abstract

Internal waves are crucial for understanding oceanographic parameters such as spatiotemporal distribution and energy transfer. They significantly impact ocean circulation, marine ecosystems, and offshore operations. However, studying internal waves is challenging due to their dynamic nature and the need for effective observation methods. [...] Read more.

Internal waves are crucial for understanding oceanographic parameters such as spatiotemporal distribution and energy transfer. They significantly impact ocean circulation, marine ecosystems, and offshore operations. However, studying internal waves is challenging due to their dynamic nature and the need for effective observation methods. This study investigated nonlinear internal solitary waves (ISWs) in the South China Sea using SSHa data from the SWOT satellite mission (Cycles 2 to 20). The distribution patterns and seasonal variations in ISWs were analyzed, revealing that ISWs are more frequently observed in summer while being rarely detected in winter. By combining SSHa observations with a Mode-1 vertical structure model, the isopycnal displacement, velocity fields, and energy characteristics of ISWs were reconstructed. The results show a maximum isopycnal displacement of 160 m at 400 m depth and peak kinetic energy near the surface (~2000 J/m³) and potential energy at a depth of around 300 m (~9000 J/m³). These findings highlight the vertical variability of ISWs and demonstrate the capability of SWOT data in capturing their fine-scale evolution, providing new opportunities for oceanic research and enhancing our understanding of internal waves’ impact on marine environments and ocean circulation. Full article

(This article belongs to the Special Issue Monitoring of Ocean Surface Currents and Circulation)

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38 pages, 4192 KiB

Open AccessArticle

Integrated Navigation Algorithm for Autonomous Underwater Vehicle Based on Linear Kalman Filter, Thrust Model, and Propeller Tachometer

by Haosu Zhang, Yueying Cai, Jin Yue, Wei Mu, Shiyin Zhou, Defei Jin and Lingji Xu

J. Mar. Sci. Eng. 2025, 13(2), 303; https://doi.org/10.3390/jmse13020303 - 6 Feb 2025

Viewed by 284

Abstract

For the purpose of reducing the cost, size, and weight of the integrated navigation system of an AUV (autonomous underwater vehicle), and improving the stealth of this system, an integrated navigation algorithm based on a propeller tachometer is proposed. The algorithm consists of [...] Read more.

For the purpose of reducing the cost, size, and weight of the integrated navigation system of an AUV (autonomous underwater vehicle), and improving the stealth of this system, an integrated navigation algorithm based on a propeller tachometer is proposed. The algorithm consists of five steps: ① establishing the resistance model of AUV, ② establishing the thrust model, ③ utilizing the measured speeds obtained from the AUV’s voyage trials for calibration, ④ discrimination and replacement of outliers from the tachometer measurements, and ⑤ establishing a linear Kalman filter (LKF) with water currents as state variables. This paper provides the modeling procedure, formula derivations, model parameters, and algorithm process, etc. Through research and analysis, the proposed algorithm’s accuracy has been improved. The specific values of the localization error are detailed in the main text. Therefore, the proposed algorithm has high accuracy, a strong anti-interference capability, and good robustness. Moreover, it exhibits certain adaptability to complex environments and value for practical engineering. Full article

(This article belongs to the Section Ocean Engineering)

24 pages, 11379 KiB

Open AccessArticle

A Low-Power Consumption Deepwater Subsea Electric Gate Valve Actuator, Part A: Prototype and Test

by Wenlong Zhang, Peng Jia, Huailiang Zheng, Gang Wang, Tao Wang, Xiangyu Wang, Feihong Yun and Mengxuan Wu

J. Mar. Sci. Eng. 2025, 13(2), 302; https://doi.org/10.3390/jmse13020302 - 6 Feb 2025

Viewed by 274

Abstract

All-electric systems represent the current development trend in subsea control systems, and the subsea electric gate valve actuator is the core equipment item in all-electric subsea control systems. To solve the problems of the traditional subsea electric gate valve actuator with low safety, [...] Read more.

All-electric systems represent the current development trend in subsea control systems, and the subsea electric gate valve actuator is the core equipment item in all-electric subsea control systems. To solve the problems of the traditional subsea electric gate valve actuator with low safety, poor reliability, and high energy consumption, in this paper, a new subsea electric gate valve actuator configuration concept is proposed, where the actuator has a redundant drive, a low-power holding function, a fail-safe shutdown mechanism, an emergency operation capability, and other functions. An actuator prototype was developed, an actuator integration test system was constructed, and the prototype actuator was combined with a standard subsea gate valve, an all-electric subsea control module, and other equipment to conduct several functional tests. The test results show that the actuator functions and performance indicators meet the designed requirements. Compared with the existing actuators, in addition to high reliability and safety, the driving power consumption can be reduced by 5% and holding power consumption can be reduced by 40%. Full article

(This article belongs to the Section Ocean Engineering)

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14 pages, 7836 KiB

Open AccessArticle

Shallow Gas Distribution Influenced by the Interface of Sedimentary Facies in the Southwest of the Qiongdongnan Basin

by Taotao Yang, Xiaohan Li, Jiapeng Jin, Jianwei Chen, Zhi Gong, Li Zhao, Wenlong Wang, Bo Liu, Jinzi Hu, Wenlu Wang and Xiujuan Wang

J. Mar. Sci. Eng. 2025, 13(2), 301; https://doi.org/10.3390/jmse13020301 - 6 Feb 2025

Viewed by 370

Abstract

Shallow gas, with huge resources, has been confirmed using three dimensional (3D) seismic data and more than 20 drilling sites in the deep water of the LS36 gas field, the Qiongdongnan Basin, the South China Sea. The interface of sedimentary facies in the [...] Read more.

Shallow gas, with huge resources, has been confirmed using three dimensional (3D) seismic data and more than 20 drilling sites in the deep water of the LS36 gas field, the Qiongdongnan Basin, the South China Sea. The interface of sedimentary facies in the southern boundary of the basin controls the distribution within the basin of clastic sediments coming from the north and west of the land uplifted. In this study, seismic data and geophysical attributes were used to investigate the controlling effect of the interface of sedimentary facies on the distribution of shallow gas within the basin. Our study shows that the shallow gas is mainly distributed in the Quaternary Ledong Formation in the southwest of the Qiongdongnan Basin, which was observed from acoustic impedance, amplitude versus offset (AVO), and seismic interpretations. The channelized submarine fans that onlap the interface of the sedimentary facies are distributed in a vertically stacked manner and are the main reservoirs for the shallow gas. Therefore, these sedimentary studies show that the sand-rich sediments are distributed along the interface of the sedimentary facies from the southwest to the northeast and are limited to the shallow gas within the basin. The Central Canyon provides an important deep gas source, while the flank of the canyon, gas chimney, and normal faults related to basement uplift provide pathways for vertical and lateral gas migration to form the shallow gas. This study shows that shallow gas may be widely distributed in other marginal sea basins, and sedimentary systems should be further studied in the future. Full article

(This article belongs to the Special Issue Advances in Marine Gas Hydrate Exploration and Discovery)

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32 pages, 23698 KiB

Open AccessArticle

Water Depth Correction-Based Classification Combination Method for Extracting Shallow Sea Reef Geomorphological Information: A Case Study of Xisha Chau and Zhaoshu Island

by Zhigang Lu, Weidong Zhu, Daxing Lei, Yi Zhu, Yifan Chen, Zilin Yue and Zhongqiang Wu

J. Mar. Sci. Eng. 2025, 13(2), 300; https://doi.org/10.3390/jmse13020300 - 6 Feb 2025

Viewed by 399

Abstract

Remote sensing monitoring and geomorphologic change analysis of coral reefs are of great practical significance for the ecological protection and sustainable development of coral reef area resources. A WBMD scheme is proposed to better extract coral reef information from island environments of Xisha, [...] Read more.

Remote sensing monitoring and geomorphologic change analysis of coral reefs are of great practical significance for the ecological protection and sustainable development of coral reef area resources. A WBMD scheme is proposed to better extract coral reef information from island environments of Xisha, China. Satellite imagery, after preprocessing, is subjected to water depth correction to mitigate the influence of water depth on reflectance. A maximum likelihood classification model is then used for geomorphological classification, followed by refinement through a decision tree classification model, forming the WBMD scheme. The overall accuracy of geomorphological classification for Xisha Chau and Zhaoshu Island based on the WBMD scheme was 97.07% and 95.07%. Using this scheme to analyze the geomorphology of Xisha Chau and Zhaoshu Island from 2014 to 2018 reveals that the degradation of coral reef on Xisha Chau is mainly distributed in the lagoon slope and around the lagoon, and the lagoon area on Zhaoshu Island has been shrinking year by year, while the area of the gray sand island has increased, and the areas of other geomorphological types exhibit fluctuating changes. Previous studies on coral reefs have indicated that coral reefs are mainly distributed in the lagoon slope area, where significant coral reef degradation has also been observed, raising an alarm for coral reef conservation efforts in China. Full article

(This article belongs to the Special Issue New Advances in Marine Remote Sensing Applications)

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19 pages, 848 KiB

Open AccessArticle

Quantitative Assessment of Vessel Traffic Service Center Workload: Development and Validation of the Vessel Traffic Service Operator Workload Index (VOWI)

by Gil-Ho Shin, Chae-Uk Song and Daewon Kim

J. Mar. Sci. Eng. 2025, 13(2), 299; https://doi.org/10.3390/jmse13020299 - 6 Feb 2025

Viewed by 469

Abstract

This study addresses the critical challenge of lacking quantitative measures for objective evaluation of vessel traffic service (VTS) operator workload, where current uniform staffing approaches fail to reflect center-specific operational characteristics. The VTS Operator Workload Index (VOWI) model was developed using the Delphi–AHP [...] Read more.

This study addresses the critical challenge of lacking quantitative measures for objective evaluation of vessel traffic service (VTS) operator workload, where current uniform staffing approaches fail to reflect center-specific operational characteristics. The VTS Operator Workload Index (VOWI) model was developed using the Delphi–AHP methodology to determine the relative importance of key factors including traffic, sea area characteristics, port facilities, and weather conditions, which formed the basis for calculating both center-wide and per-operator workload indices. Factor analysis revealed that traffic factors showed the highest importance at 0.4627, followed by sea area (0.1960), port facilities (0.1916), and weather (0.1497) factors. Application of the VOWI model to 19 VTS centers in South Korea demonstrated that per-operator workload at Busan, Incheon, and Ulsan VTS was up to three times higher than at other centers. This finding indicates that the current uniform staffing approach based on sector count inadequately reflects each center’s actual operational characteristics. The VOWI model provides objective criteria for efficient personnel management in VTS centers and is expected to contribute to improving VTS service quality. Full article

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J. Mar. Sci. Eng., Volume 13, Issue 2 (February 2025) – 144 articles

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