J. Mar. Sci. Eng., Volume 12, Issue 1 (January 2024) – 197 articles

The problem of periodic oscillations of a dipole, specifically its strength, along the principal axes in a three-dimensional frozen channel is considered. The key points of the problem are taking into account the linear thickness of ice across the channel and ice porosity within Darcy’s law. The fluid in the channel is inviscid and incompressible; the flow is potential. It is expected that the oscillations of a small radius dipole well approximate the oscillations of a small radius sphere at a sufficient depth of immersion of the dipole. It was found that during oscillations along the channel and vertical oscillations, waves are generated in the channel, propagating along the channel with a frequency equal to the frequency of dipole oscillations. These waves decay far from the dipole, and the rate of decay depends on the porosity coefficient. Full article

Image recognition is vital for intelligent ships’ autonomous navigation. However, traditional methods often fail to accurately identify maritime objects’ spatial positions, especially under electromagnetic silence. We introduce the StereoYOLO method, an enhanced stereo vision-based object recognition and localization approach that serves autonomous vessels using only image sensors. It is specifically refined for maritime object recognition and localization scenarios through the integration of convolutional and coordinated attention modules. The method uses stereo cameras to identify and locate maritime objects in images and calculate their relative positions using stereo vision algorithms. Experimental results indicate that the StereoYOLO algorithm boosts the mean Average Precision at IoU threshold of 0.5 (mAP50) in object recognition by 5.23%. Furthermore, the variation in range measurement due to target angle changes is reduced by 6.12%. Additionally, upon measuring the distance to targets at varying ranges, the algorithm achieves an average positioning error of 5.73%, meeting the accuracy and robustness criteria for maritime object collision avoidance on experimental platform ships. Full article

Constant changes occur in coastal areas over different timescales, requiring observation and modeling. Specifically, modeling morphological changes resulting from short-term events, such as storms, is of great importance in coastal management. Parameter calibration is necessary to achieve more accurate simulations of process-based models that focus on specific locations and event characteristics. In this study, the XBeach depth-averaged model was adopted to simulate subaerial data pre- and post-storms, and overwash phenomena were observed using the data acquired through unmanned aerial vehicles. The parameters used for the model calibration included those proposed in previous studies. However, an emphasis was placed on calibrating the parameters related to sediment transport that were directly associated with overwash and deposition. Specifically, the parameters corresponding to the waveform parameters, wave skewness, and wave asymmetry were either integrated or separated to enable an adequate representation of the deposition resulting from overwash events. The performance and sensitivity of the model to changes in volume were assessed. Overall, the waveform parameters exhibit significant sensitivity to volume changes, forming the basis for calibrating the deposition effects caused by overwashing. These results are expected to assist in the more effective selection and calibration of parameters for simulating sediment deposition due to overwash events. Full article

This paper proposes a version of the deep-sea environment simulated test system for subsea control modules to solve the problem of incomplete testing systems for electro-hydraulic subsea control modules. Based on the subsea control module test requirements specified in APISTD17F, the test system in this paper is a highly integrated system, including a test hydraulic power unit, a control module test bench, a signal simulator, an electronic test unit, an umbilical simulator, a high-pressure chamber, and an incubator. Firstly, the design indicators of the test system were determined by analyzing the various functions of the subsea control module and its working environment. Secondly, the design scheme for the test system was proposed, and a detailed design was carried out. Finally, a hydro-electrical subsea control module for the Bohai Sea was fully tested with this system, with tests including the qualification test and the factory acceptance test. The test results show that all parts of the test system coordinated well and have achieved the design indicators, and the test system can simulate the working environment and complete a land test. The effectiveness and feasibility of the test system have been verified through the test. By adopting this system, the risk of subsea control module failure can be minimized, laying the foundations for future research and improvement of subsea control module testing equipment. Full article

Using a three-dimensional coupled physical–biological model, this paper explores the effect that short-lived wind events lasting a few days in duration have on the creation of phytoplankton blooms in island wakes. Findings show that wind-induced coastal upwelling creates initial nutrient enrichment and phytoplankton growth near the island, whereas an oscillating flow, typical of island wakes, expels patches of upwelled water, including its nutrient and phytoplankton loads, into the ambient ocean. Dependent on the wind direction, a short-lived wind event can create one or more plankton patches with diameters of the order of the island diameter. Phytoplankton continues to grow within floating patches, each forming an individual marine ecosystem. While the ecological features of island wakes are well documented, this study is the first that describes the significance of short-lived, transient wind-driven upwelling in the process. Full article

This study introduces a groundbreaking approach for real-time 3D localization, specifically focusing on achieving seamless and precise localization during the terminal guidance phase of an autonomous underwater vehicle (AUV) as it approaches an omnidirectional docking component in an automated deployable launch and recovery system (LARS). Using the AUV’s magnetometer, an economical electromagnetic beacon embedded in the docking component, and an advanced signal processing algorithm, this novel approach ensures the accurate localization of the docking component in three dimensions without the need for direct line-of-sight contact. The method’s real-time capabilities were rigorously evaluated via simulations, prototype experiments in a controlled lab setting, and extensive full-scale pool experiments. These assessments consistently demonstrated an exceptional average positioning accuracy of under 3 cm, marking a significant advancement in AUV guidance systems. Full article

In order to enhance the power generation efficiency and reliability of wave energy converters (WECs), an enclosed inertial WEC with a magnetic nonlinear stiffness mechanism (nonlinear EIWEC) is proposed in this paper. A mathematical model of the nonlinear EIWEC was established based on the Cummins equation and the equivalent magnetic charge method, and the joint simulations were carried out using MATLAB/Simulink 2020 and AMESim 2020 softwares. The effect of the magnetic nonlinear stiffness mechanism (NSM) on the performance of the EIWEC system was investigated. The results show that the nonlinear negative stiffness property of NSM can significantly improve the motion response and output power of EIWEC under low-frequency waves. Compared to EIWEC without NSM (linear EIWEC), nonlinear EIWEC has a higher generation efficiency and wider frequency bandwidth. Additionally, the effects of linear spring, internal mass body, and hydraulic power take-off (PTO) system parameters on the energy conversion capability of the system were analyzed to provide a reference for the design of nonlinear EIWECs. In general, the proposed nonlinear EIWEC could provide good development potential for the scale utilization of wave energy resources. Full article

Accurate ship object detection ensures navigation safety and effective maritime traffic management. Existing ship target detection models often have the problem of missed detection in complex marine environments, and it is hard to achieve high accuracy and real-time performance simultaneously. To address these issues, this paper proposes a lightweight ship object detection model called YOLOv7-Ship to perform end-to-end ship detection in complex marine environments. At first, we insert the improved “coordinate attention mechanism” (CA-M) in the backbone of the YOLOv7-Tiny model at the appropriate location. Then, the feature extraction capability of the convolution module is enhanced by embedding omnidimensional dynamic convolution (ODconv) into the efficient layer aggregation network (ELAN). Furthermore, content-aware feature reorganization (CARAFE) and SIoU are introduced into the model to improve its convergence speed and detection precision for small targets. Finally, to handle the scarcity of ship data in complex marine environments, we build the ship dataset, which contains 5100 real ship images. Experimental results show that, compared with the baseline YOLOv7-Tiny model, YOLOv7-Ship improves the mean average precision (mAP) by 2.2% on the self-built dataset. The model also has a lightweight feature with a detection speed of 75 frames per second, which can meet the need for real-time detection in complex marine environments to a certain extent, highlighting its advantages for the safety of maritime navigation. Full article

Suction anchors play a crucial role as marine supporting infrastructure within mooring systems. In engineering practice, the composite load comprising nonlinear waves and cyclic pull-out loads can have adverse effects on the seabed soil, posing a threat to the pull-out bearing capacity of the suction anchor. While existing research predominantly focuses on cyclic pull-out loads, the influence of nonlinear wave actions at the seabed surface remains overlooked. This study employs a two-dimensional integrated numerical model to investigate the dynamic soil response around a suction anchor under the influence of both nonlinear waves and cyclic pull-out loads, focusing on the mechanisms that lead to liquefaction and the deterioration of the interfacial friction due to the excess pore pressure buildup. The numerical results reveal that the cyclic pull-out load is the primary factor in the deterioration of the frictional resistance at the suction–soil interface, especially when the pull-out load is inclined with the suction anchor. Parametric studies indicate that the relative difference in frictional resistance deterioration between cases considering and excluding surface water waves becomes more pronounced in soils characterized by a small consolidation coefficient ($C_v$) and relative density ($D_r$). Full article

The vertical ice breaking of marine structures in ice-covered areas involves the deformation and failure of an ice sheet. Different from the existing conventional scenarios where the ice sheet is used as a transportation and support medium, the damage to the ice sheet will be more severe when a structure penetrates the ice sheet from below, due to the lack of elastic support from the fluid above the ice sheet. In order to investigate the failure mode of the ice sheet and the ice load characteristics during vertical penetration, a mesh-free bond-based peridynamic method is used in this paper to simulate the mechanical behaviors of the ice sheet. The cracks simulated in this study exhibit a higher level of similarity to experimental results, which improves the accuracy of the ice load. The numerical model established shows satisfactory applicability for the analysis of penetration failure of an ice sheet. In addition, the influence of ice thickness, impact velocity, and cylinder diameter on the failure characteristics of the ice sheet and breakthrough load are analyzed. The results of a parametric study indicate that the relationship between ice thickness and breakthrough load, as well as the relationship between load area and breakthrough pressure, can both be fitted using quadratic functions. Full article

In recent years, multi-bucket foundations have been studied and gradually adopted in engineering practices as a novel foundation for offshore wind turbines within a range of water depth of 30 to 50 m. This study investigated the motion characteristics of air-floating tripod bucket foundation (AFTBF) through a series of experiments during free air-floating. The experimental results show that the surge force appears to be the most important factor influencing pitch moment and motion, whether it is a change in water depth or a draft for AFTBF. The maximum amplitudes of surge acceleration and pitch angle show a trend of increasing with narrower spacing and decreasing with wider spacing, while the heave acceleration shows an opposite trend. The added mass and damping of heave motion for AFTBF increase with shallower water due to the increasing pressure difference between the inside and bottom of bucket foundation. The shallower the water depth and the larger the draft, the longer the resonance period of heave. Full article

Global degradation of coral reefs is reflected in the destruction of shelters in various environments and threatens the stability of marine ecosystems. Artificial shelters offer an alternative, but their design could be more challenging due to limited knowledge regarding desired inhabitants’ shelter characteristics and preferences. Investigating these preferences is resource-intensive, particularly regarding small shelters that mimic natural reef conditions. Furthermore, for statistical analysis in small shelters, fish abundance may need to be higher. We propose a method to characterize the species-specific shelter preferences using low-volume data. During a study conducted from January 2021 to April 2022, round clay artificial shelters (RAS) were deployed on an abandoned oil pier to examine a coral reef fish community. We recorded 92 species from 30 families and grouped them into systematic (families) and functional (dietary group) classes. Grouping enabled us to examine each group’s preference, while crossing these group preferences revealed species-specific preferences, which matched field observations. This approach proved effective in profiling the shelter preferences of 17 species while having limited resources. These profiles may later allow the establishment of ecological-oriented artificial reefs. Moreover, this method can be applied to other applications using other shelter designs, sizes, and research sites. Full article

With the extensive application of sensor technology in scientific ocean research, ocean resource exploration, underwater engineering construction, and other fields, underwater target positioning technology has become an important support for the ocean field. This paper proposes a robust positioning algorithm that combines the disadvantages of distributed estimation and particle swarm optimization, which can solve the large localization error problem caused by uncertainties in underwater acoustic communication and sampling processes. Considering the presence of ranging anomalies and sampling packet loss in underwater acoustic measurements, a weighted coupling filling method is used to correct the outliers in an underwater acoustic ranging signal. Based on the mapping model from the element array to the underwater acoustic responder, an unconstrained optimization algorithm for one-time localization estimation of underwater acoustic targets was established. Based on the one-time localization estimation results of underwater acoustic targets, an improved multi-particle swarm optimization estimation based on interactive search is proposed, which improves the accuracy of underwater target localization. The numerical results show that the positioning accuracy of the proposed algorithm can be effectively enhanced in cases of distance measurement errors and azimuth measurement errors. Compared with the positioning error before optimization, the positioning error can be reduced after optimization. Additionally, the experiment was carried out in the underwater environment of Hangzhou Qiandao Lake, which verified the positioning performance of the proposed algorithm. Full article

To effectively address the increase in maritime accidents and the challenges posed by the trend toward larger ships for maritime safety, it is crucial to rationally allocate the limited maritime search and rescue (MSAR) resources and enhance accident response capabilities. We present a comprehensive method for allocating MSAR resources, aiming to improve the overall efficiency of MSAR operations. First, we use long short-term memory to predict the number of future accidents and employ the K-medoids algorithm to identify the accident black spots in the studied area. Next, we analyze the multi-constraint conditions in the MSAR resource allocation process. A multi-objective integer programming model is constructed to minimize the response time and allocation cost. Finally, we use the non-dominated sorting genetic algorithm II (DNSGA-II) with Deb’s rules to solve the model, and we propose a multi-attribute decision optimization-based method for MSAR resource allocation. We found that the DNSGA-II exhibits better convergence and generates higher-quality solutions compared to the NSGA-II, particle swarm optimization (PSO), and enhanced particle swarm optimization (EPSO) algorithms. Compared with the existing MSAR resource emergency response system, the optimized scheme reduces the response time and allocation cost by $11.32\%$ and $6.15\%$, respectively. The proposed method can offer decision makers new insights when formulating MSAR resource allocation plans. Full article

The effluent discharged from wastewater treatment facilities frequently enters the ocean, posing a considerable threat to the health of marine life and humans. In this paper, an alkali lignin-based biochar-loaded modified Fe–Cu catalyst (FeCu@BC) was prepared to remove soluble microbial products (SMP) from secondary effluent as disinfection by-products precursors at ambient temperature and pressure. The humic acid (HA) was taken as the representative substance of SMP. The results showed that the maximum removal efficiency of HA reached 93.2% when the FeCu@BC dosage, pH, initial HA concentration, and dissolved oxygen concentration were 5.0 g/L, 7, 100 mg/L, and 1.75 mg/L, respectively. After three cycles, the removal efficiency of HA could be maintained at more than 70%. The quenching experiments and electron spin resonance (EPR) results showed that •OH and ¹O₂ were involved in the degradation of HA in the FeCu@BC catalyst reaction system, with ¹O₂ playing a dominant role. Theoretical calculations confirmed that •OH and ¹O₂ were more prone to attack the C=O bond of the side chain of HA. After processing by the FeCu@BC catalyst, the yield of chlorinated disinfection by-products from secondary effluent had decreased in an obvious manner. This study provides a new solution to efficiently solve the problem of chlorinated disinfection by-products from HA. Full article

Port operations have been suffering from hybrid uncertainty, leading to various disruptions in efficiency and tenacity. However, these essential uncertain factors are often considered separately in literature during berth and quay crane assignments, leading to defective, even infeasible schedules. This paper addressed the integrated berth allocation and quay crane assignment problem (BACAP) with stochastic vessel delays under different conditions. A novel approach that combines both proactive and reactive strategies is proposed. First, a mixed-integer programming model is formulated for BACAP with quay crane maintenance activities under the ideal state of no delay. Then, for minor delays, buffer time is added to absorb the uncertainty of the arrival time of vessels. Thus, a robust optimization model for minimizing the total service time of vessels and maximizing the buffer time is developed. Considering that the schedule is infeasible when a vessel is seriously delayed, a reactive model is built to minimize adjustment costs. According to the characteristics of the problem, this article combined local search with the genetic algorithm and proposed an improved genetic algorithm (IGA). Numerical experiments validate the efficiency of the proposed algorithm with CPLEX and Squeaky Wheel Optimization (SWO) in different delay conditions and problem scales. An in-depth analysis presents some management insights on the coefficient setting, uncertainty, and buffer time. Full article

The glycoside hydrolase 107 (GH107) family includes fucanase enzymes from only two bacterial phyla, Bacteroidota and Pseudomonadota. The goal of this work was to explore the diversity of putative fucanase enzymes related to this family in organisms of the PVC superphylum (Planctomycetota, Verrucomicrobiota, Chlamydiota), in order to expand our knowledge of the fucoidan-degrading potential in this ecologically and biotechnologically relevant group. Using hidden Markov model- and peptide-based annotation tools, 26 GH107 homolog sequences were identified in metagenome and genome datasets. The sequences formed two distinct clusters in a phylogenetic analysis, only one including members of the GH107 family. The endo-acting fucoidan degrading activity was confirmed in an enzyme included in the most divergent cluster. The fucanase, which probably originated in an uncultured planctomycete from the sampled subantarctic sediments, was cloned and expressed in Escherichia coli. The enzyme catalyzed the rapid hydrolysis of internal glycosidic bonds of fucoidan from Macrocystis pyrifera, a macroalgae species abundant at the site. It was active in a wide range of temperatures (5–45 °C), salinities (9.5–861 mM NaCl), and pH values (4.5–9), mainly producing sulfated α-(1,3)-linked fuco-oligosaccharides of various lengths. The PVC superphylum represents a promising source of fucanase enzymes with various biotechnological applications. Full article

Capsizing accidents are regarded as marine accidents with a high rate of casualties per accident. Approximately 89% of all such accidents involve small ships (vessels with gross tonnage of less than 10 tons). Stability calculations are critical for assessing the risk of capsizing incidents and evaluating a ship’s seaworthiness. Despite the high frequency of capsizing accidents involving them, small ships are generally exempt from adhering to stability regulations, thus remaining systemically exposed to the risk of capsizing. Moreover, the absence of essential design documents complicates direct ship stability calculations. This study utilizes hull form feature data—obtained from the general arrangement of small ships—as input for a deep learning model. The model is structured as a multilayer neural network and aims to infer hydrostatic curves, which are required data for stability calculations. Full article

The development of intelligent task allocation and path planning algorithms for unmanned surface vehicles (USVs) is gaining significant interest, particularly in supporting complex ocean operations. This paper proposes an intelligent hybrid algorithm that combines task allocation and path planning to improve mission efficiency. The algorithm introduces a novel approach based on a self-attention mechanism (SAM) for intelligent task allocation. The key contribution lies in the integration of an adaptive distance field, created using the locking sweeping method (LSM), into the SAM. This integration enables the algorithm to determine the minimum practical sailing distance in obstacle-filled environments. The algorithm efficiently generates task execution sequences in cluttered maritime environments with numerous obstacles. By incorporating a safety parameter, the enhanced SAM algorithm adapts the dimensional influence of obstacles and generates paths that ensure the safety of the USV. The algorithms have been thoroughly evaluated and validated through extensive computer-based simulations, demonstrating their effectiveness in both simulated and practical maritime environments. The results of the simulations verify the algorithm’s capability to optimize task allocation and path planning, leading to improved performance in complex and obstacle-laden scenarios. Full article

The seasonal dynamics of the NE Black Sea phytoplankton follow the following pattern: small diatoms (spring) → coccolithophorid Emiliania huxleyi (late spring–early summer) → large diatoms (summer). Our hypothesis states that nitrogen and phosphorus concentrations regulate the seasonal phytoplankton dynamics. A minimum number of parameters is enough to understand the mechanisms of dominant species change. Based on the concept of intracellular regulation, the following parameters were evaluated: the minimum nitrogen and phosphorus quotas; half-saturation constants for nitrogen and phosphorus uptake; the maximum specific growth rate of the dominant phytoplankton species. Computational experiments on the model show the following: (1) in spring, a species with a high maximum specific growth rate becomes dominant; (2) in late spring and early summer, a species with a low minimum nitrogen quota and a low half-saturation constant for nitrogen uptake is observed; (3) in summer, a low minimum phosphorus quota and a low half-saturation constant for phosphorus uptake allow the species to become dominant. Full article

In tsunami studies, understanding the intricate dynamics in the swash area, characterised by the shoaling effect, remains a challenge. In this study, we employed the adaptive mesh refinement (AMR) method to model tsunami inundation and propagation in the Onagawa town physical flume experiment. Using the open-source flow solver Basilisk, we implemented the Saint-Venant (SV) equations, Serre–Green–Naghdi (SGN) equations, and a nonhydrostatic multilayer (ML) extension of the SGN equations. A hydraulic bore tsunami-like wave was used as the input boundary condition. The objective was to assess the efficiency of the AMR method with nonhydrostatic tsunami models in overcoming limitations in 2D and quasi-3D models in flume experiments, particularly with respect to improving accuracy in arrival time and run-up detection. The results indicate improved performance of the SGN and SV models in determining tsunami arrival times. The ML model demonstrated enhanced wave run-up simulations on complex built-in terrain. The refined roughness coefficient determined using the ML solver captured the arrival time well in the northern section of the Onagawa model, albeit with a 1 s delay. The AMR method offered a computationally stable solution with an 86.3% reduction in computational time compared to a constant grid. While effective, the nonhydrostatic models entail the use of a great deal of computational resources. Full article

The foundations of offshore wind power can be classified as floating, tripod, jacket, monopile, or gravity-based, depending on the support type. In the case of tripod- and jacket-type supports, the structures require precise construction. There are two main methods for installing substructures: post- and pre-piling. The post-piling method involves moving the completed substructure to the site and fixing it to the seabed by inserting a pile into the leg pile and driving it, allowing it to be constructed without special off-shore equipment; however, the construction period is long. Contrarily, the precision of foundation installation can be improved by installing a pre-piling template, which is special equipment that serves as a basic structure, on the seabed in advance, and subsequently inserting substructures. This study presents a new type of underwater pre-piling template and method for achieving optimal construction environment conditions. Construction precision was analyzed based on the wave condition, current speed, winch speed, wave direction, and current direction while the under-water template was anchored to the seabed. It was found that the wave conditions, winch speed, and vessel type had a significant influence. The results obtained considering the Douglas sea scale show that precise construction could only be achieved within Grade 2 for general barge ships, while jack-up barge ships could be used even at Grade 3 or higher. The higher the winch speed, the more stable construction becomes possible, and jack-up barges show greater constructability than general barges. Full article

The Argo buoy detects marine environmental data by making profile movements in the ocean and transmits the profile detection data to the shore base through the communication terminal. However, due to the large volume of data collected from profile detections and the continuous operation of the terminal, the remote communication of buoys is characterized by lengthy communication times and significant power consumption. A low-power Beidou transparent transmission terminal is designed to solve these problems in this paper. The terminal performs low-power operation management and power management for terminal remote communication. After the end of a communication process, the microcontroller turns the Beidou module power off and enters STOP mode. Before the next communication process begins, the serial port wakes up the microcontroller, which powers up the Beidou module. Before the remote communication, the microcontroller compacts the profile detection data collected by the buoy to reduce the quantity of remote communication data. In this paper, a variety of data compression methods are used to compare the compression rate, and the best compression method is selected according to the format characteristics of the data. The results show that the Beidou transparent transmission terminal of the Argo buoy can realize low power consumption for remote communication in ocean exploration. The terminal reduces power consumption by 77.282% per communication, and the average number of remote communications for each profile detection data are reduced by 55 times. The low-power Beidou transparent transmission terminal improves the battery life and is conducive to the long-term operation of the buoy. Full article

Coastal erosion is caused by various factors, such as harbor development along coastal areas and climate change. Erosion has been accelerated recently due to sea level rises, increased occurrence of swells, and higher-power storm waves. Proper understanding of the complex coastal erosion process is vital to prepare measures when they are needed. Monitoring systems have been widely established around a high portion of the Korean coastline, supported by several levels of governments, but valid analysis of the collected data and the following preparation of measures have not been highly effective yet. In this paper, we use a drone to obtain bed material images, and an analysis system to predict the representative grain size of beach sands from the images based on artificial intelligence (AI) analysis. The predicted grain sizes are verified via field samplings. Field bed material samples for the particle size analysis are collected during two seasons, while a drone takes photo images and the exact positions are simultaneously measured at Jangsa beach, Republic of Korea. The learning and testing results of the AI technology are considered satisfactory. Finally, they are used to diagnose the overall stability of Jangsa beach. A beach diagnostic grade is proposed here, which reflects the topography of a beach and the distribution of sediments on the beach. The developed beach diagnostic grade could be used as an indicator of any beach stability on the east coast of the Republic of Korea. When the diagnostic grade changes rapidly at a beach, it is required to undergo thorough investigation to understand the reason and foresee the future of the beach conditions, if we want the beach to function as well as before. Full article

The rhizostomatid scyphozoan Rhopilema nomadica is one of the most notorious marine invasive species established in the eastern Mediterranean Sea. Using seven microsatellite loci, here, we examined the population genetic structures on 587 individual tissue samples collected from 21 sites along the Mediterranean coast of Israel over a period of 16 years. The results indicate unique microsatellite landscapes for all samples, which belong to a single unstructured population. The >20 alleles found in most loci, low fixation index (F) values (average 0.106), and high heterozygosity (average 0.667) suggest random or assortative mating. Additionally, the low overall differentiation (Fst) values (0.043) and pairwise Fst values between the samples collected in different years indicated gene flow and random mating over the years, potentially due to the long-lasting podocytes, scyphistomae, and adults causing a population overlap between the sampled months/years. Likewise, analyses were conducted between seasons, sites, and early/intermediate/late periods of collecting years. These results support the previous analyses performed on the mitochondrial gene cytochrome oxidase subunit I (COI) sequences, altogether indicating a highly polymorphic single unstructured R. nomadica population in the Levant, possibly backed by independent introductions. The results hint to the existence of highly functional connectivity with a genetically highly diverse source population. Full article

Effective utilization of tugboats is the key to safe and efficient transport and service in ports. With the growth of maritime traffic, more and more large seaports show a trend toward becoming super-scale, and are divided into multiple specialized terminals. This paper focuses on the problem of large-scale tugboat scheduling. An optimization problem is formulated considering the cross-region constraints and uncertainties during tugboat operation. An improved genetic algorithm is proposed based on the reversal operation (GA-RE) to solve the formulated Tug-SP. A task-triggered strategy is designed for dynamic scheduling and dealing with uncertainties. Taking Zhoushan Port as a representation of multi-terminal seaports, simulation experiments are carried out to demonstrate the effectiveness of the proposed method. Compared with historical scheduling data and the standard GA, the proposed method shows good performance in solving different scale instances (including a large-scale instance of 191 ships) in terms of solution quality and computational time. Full article

Suitable colonization materials are a pursued target in marine restoration programs. Known for making nutrients available while reducing pollutants and the risk of pathogens in terrestrial ecosystems, Biochar and Bioferment materials of organic origin were tested during a two-year experiment. We tested the efficacy of these materials for restoration purposes through experimental concrete tiles treated with Biochar (B) and Bioferment (F) and tiles made of concrete, which were used as controls (Ct) for the colonization of marine organisms in the marine protected area of Porto Cesareo, Southern Italy (20 m depth). Tiles were monitored for photographs from October 2019 to September 2021. Initially, Biochar treatment presented a higher percentage of total benthic cover (81.23 ± 2.76, median ± SE), differing from Bioferment treatment and control tiles (45.65 ± 5.43 and 47.95 ± 3.69, respectively). Significant interaction between treatments and times suggests changes in community structure related to Polychaeta cover increase in Bioferment and control materials from the second monitoring time. Furthermore, the underwater instability of Bioferment on the tiles could explain the similarity with control tiles in marine organisms’ covers. Hence, Biochar is shown to be a material with optimal stability in seawater, demonstrating greater capacity for marine organisms’ colonization in less time compared to the other two materials. Full article

The morphological responses of two mesotidal beaches located in different coastal settings (embayed and open sandy beaches) on the northwestern Iberian coast were monitored during the winter of 2018/19. The offshore wave time series analysis is related to high-resolution topo-bathymetric measurements to explore spatial-temporal morphological variability at monthly to seasonal scales. Both locations are subjected to the North Atlantic wave climate which exhibits a pronounced seasonality. Throughout the last decade (2010–2020), significant wave heights reached values of up to H_s~9 m during winters and up to H_s~6 m during summers. On average, approximately 12 storms occurred annually in this region. The results clearly reveal divergent morphological responses and sediment transport behaviors at the upper beach and the intertidal zone during the winter for each location. In the embayed beach (Patos), sediment transport in the nearshore is governed by cross-shore processes between the beach berm and a submerged sandbar. In contrast, the open beach (Mira) showed dynamic sediment exchanges and three-dimensional morphologies alternating between accumulation and erosion zones. Overall, both beaches exhibited an erosional trend after the winter, particularly concerning berm erosion and the subaerial beach volume/shoreline retreat. This study highlights the contrasting morphodynamic response on open and embayed beaches to winter conditions, integrating both the subaerial and submerged zones. Local geological and environmental factors, as well as the coastal management strategies applied, will influence how the beach responds to winter wave events. Monitoring and understanding these responses are essential for effective coastal management and adaptation to changing climate. Full article