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Volume 10
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J. Mar. Sci. Eng., Volume 10, Issue 3 (March 2022) – 145 articles

Cover Story (view full-size image): Assessing environmental impacts has become a key component for the development of economic activities while preserving ecosystems' resources. Analyzing environmental DNA (eDNA) has a large potential to contribute through monitoring the composition of communities and identifying the early arrival of invasive species. To use eDNA within EIA, with the objective to infer impacts on a receptor in a defined project area, it will be necessary to quantify the processes that govern the dynamics of DNA in the environment. In marine systems, comprehensive mathematical models coupling hydrodynamics and the dynamics of eDNA are poised to become viable tools to explain these dynamics. View this paper
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23 pages, 15097 KiB  
Article
Simulation of Marine Leisure Accidents Using Random-Walk Particle Tracking on Macro-Tidal Environment
by Hyeon-Jeong Kim and Seung-Won Suh
J. Mar. Sci. Eng. 2022, 10(3), 447; https://doi.org/10.3390/jmse10030447 - 21 Mar 2022
Cited by 1 | Viewed by 1945
Abstract
In the west coast of Korea (WCK), macro-tidal environments with wide tidal flats yield distinctive characteristics such as recursive tidal currents and tidal asymmetry. Here, we proposed an efficient search and rescue (SAR) computation method for WCK conditions (where bottom shapes affect nearshore [...] Read more.
In the west coast of Korea (WCK), macro-tidal environments with wide tidal flats yield distinctive characteristics such as recursive tidal currents and tidal asymmetry. Here, we proposed an efficient search and rescue (SAR) computation method for WCK conditions (where bottom shapes affect nearshore sticking) using a finely resolved wet–dry circulation model. A random-walk particle tracking module (PTM) was applied to an unstructured finite element model to provide the SAR information needed to mitigate the consequences of marine leisure accidents. To capture the unique external forcing characteristics affecting the nearshore SAR case, sensitivity tests, which considered the characteristics of human bodies in particle representation, were performed on an idealized basin under typical external forcing. Furthermore, the effects of surface drag were included to represent real conditions more accurately. Our simulations showed that the accuracy of initial accident times for in situ mannequin floating tests (where several initial locations and times of accidents were used) directly affected the accuracy and effectiveness of SAR missions. However, to understand and predict the missing floating person in real time, additional intensive field experiments are required that account for the local geomorphological characteristics, external real-time temporal tides, and wind forcing incorporating extreme weather conditions. Full article
(This article belongs to the Section Coastal Engineering)
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14 pages, 3804 KiB  
Article
Influence of Anaerobic Degradation of Organic Matter on the Rheological Properties of Cohesive Mud from Different European Ports
by Ahmad Shakeel, Florian Zander, Julia Gebert, Claire Chassagne and Alex Kirichek
J. Mar. Sci. Eng. 2022, 10(3), 446; https://doi.org/10.3390/jmse10030446 - 21 Mar 2022
Cited by 2 | Viewed by 1841
Abstract
The presence of clay-organic flocs in cohesive mud results in a complex rheological behavior of mud, including viscoelasticity, shear-thinning, thixotropy and two-step yielding. In this study, the effect of microbial degradation of organic matter on the rheological properties of mud samples, collected from [...] Read more.
The presence of clay-organic flocs in cohesive mud results in a complex rheological behavior of mud, including viscoelasticity, shear-thinning, thixotropy and two-step yielding. In this study, the effect of microbial degradation of organic matter on the rheological properties of mud samples, collected from different ports, was examined. The mud samples were collected from five different European ports (Port of Antwerp (PoA), Port of Bremerhaven (PoB), Port of Emden (PoE), Port of Hamburg (PoH) and Port of Rotterdam (PoR)), displaying varying sediment properties. The rheological analysis of fresh and degraded mud samples was performed with the help of several tests, including stress ramp-up tests, amplitude sweep tests, frequency sweep tests, time-dependent tests and structural recovery tests. The results showed: (i) a significant decrease in yield stresses and complex modulus after organic matter degradation for mud samples from PoA, PoH and PoR, (ii) a negligible change in rheological properties (yield stresses, crossover amplitude and complex modulus) for mud samples from PoB, and (iii) a significant increase in rheological properties for mud samples from PoE. For time-dependent tests, mud samples from PoB showed a substantial increase in hysteresis (~50% mean value) as compared to the changes in yield stresses and crossover amplitude. The analysis of gas production during degradation of organic matter showed a (i) significant release of carbon per g dry matter for mud samples from PoA, PoH and PoR, (ii) lower carbon release per g dry matter for mud samples from PoB, and (iii) a negligible carbon release per g dry matter for mud samples from PoE, which corresponded well with the change in rheological properties. Full article
(This article belongs to the Special Issue Sediment Remediation at Harbour)
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19 pages, 9837 KiB  
Article
An Original Vibrodiagnostic Device to Control Linear Rolling Conveyor Reliability
by Radka Jírová, Lubomír Pešík and Robert Grega
J. Mar. Sci. Eng. 2022, 10(3), 445; https://doi.org/10.3390/jmse10030445 - 21 Mar 2022
Cited by 2 | Viewed by 1705
Abstract
On the basis of an analysis of the number of goods that are transported and handled in maritime transport, the ports for cargo ships may be considered as places with concentrated emissions. Reducing the emissions in ports can be achieved by shortening the [...] Read more.
On the basis of an analysis of the number of goods that are transported and handled in maritime transport, the ports for cargo ships may be considered as places with concentrated emissions. Reducing the emissions in ports can be achieved by shortening the stay times of cargo ships. The time that ships spend in ports may be reduced to the time that is required for the effective handling of the goods. One of the solutions for effective handling is using equipment with linear rolling systems. To prevent the idle time of cargo ships and the unnecessary increment of emissions in ports because of the possible failure of the linear rolling systems, their reliability and failure prediction are greatly required. Unfortunately, the common diagnostic systems of linear rolling systems in transportation practice still fail in particular cases of great external loads. Therefore, an original solution of the diagnostic system was designed on the basis of a load-free diagnostic part with a vibration sensor that is integrated into a carriage of the linear rolling system. A functional sample of the diagnostics was produced, and the vibrations that were measured on a loaded carriage and on the diagnostic part were compared in laboratory conditions under significant external loads. Encouraging results were reached by a time-domain analysis of the measured data. On the diagnostic part, the damage appeared clearly, while, on the loaded carriage, there were no observable signs of damage. Full article
(This article belongs to the Special Issue Marine Engines Performance and Emissions II)
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16 pages, 3572 KiB  
Article
Real-Time Ship Tracking under Challenges of Scale Variation and Different Visibility Weather Conditions
by Hu Liu, Xueqian Xu, Xinqiang Chen, Chaofeng Li and Meilin Wang
J. Mar. Sci. Eng. 2022, 10(3), 444; https://doi.org/10.3390/jmse10030444 - 20 Mar 2022
Cited by 6 | Viewed by 2319
Abstract
Visual ship tracking provides crucial kinematic traffic information to maritime traffic participants, which helps to accurately predict ship traveling behaviors in the near future. Traditional ship tracking models obtain a satisfactory performance by exploiting distinct features from maritime images, which may fail when [...] Read more.
Visual ship tracking provides crucial kinematic traffic information to maritime traffic participants, which helps to accurately predict ship traveling behaviors in the near future. Traditional ship tracking models obtain a satisfactory performance by exploiting distinct features from maritime images, which may fail when the ship scale varies in image sequences. Moreover, previous frameworks have not paid much attention to weather condition interferences (e.g., visibility). To address this challenge, we propose a scale-adaptive ship tracking framework with the help of a kernelized correlation filter (KCF) and a log-polar transformation operation. First, the proposed ship tracker employs a conventional KCF model to obtain the raw ship position in the current maritime image. Second, both the previous step output and ship training sample are transformed into a log-polar coordinate system, which are further processed with the correlation filter to determine ship scale factor and to suppress the negative influence of the weather conditions. We verify the proposed ship tracker performance on three typical maritime scenarios under typical navigational weather conditions (i.e., sunny, fog). The findings of the study can help traffic participants efficiently obtain maritime situation awareness information from maritime videos, in real time, under different visibility weather conditions. Full article
(This article belongs to the Special Issue Marine Intelligent Transportation Systems: Data Mining and Control Optimization)
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18 pages, 7871 KiB  
Article
Seasonal Pattern of the Effect of Slurry Ice during Catching and Transportation on Quality and Shelf Life of Gilthead Sea Bream
by Athina Ntzimani, Rafael Angelakopoulos, Natalia Stavropoulou, Ioanna Semenoglou, Efimia Dermesonlouoglou, Theofania Tsironi, Katerina Moutou and Petros Taoukis
J. Mar. Sci. Eng. 2022, 10(3), 443; https://doi.org/10.3390/jmse10030443 - 19 Mar 2022
Cited by 3 | Viewed by 2371
Abstract
The objective of the present study was the evaluation of the effect of slurry ice, as an alternative cooling medium during harvesting and transportation, on the quality parameters (e.g., microbiological stability, sensory attributes, physicochemical changes) and shelf life of fish. The effect of [...] Read more.
The objective of the present study was the evaluation of the effect of slurry ice, as an alternative cooling medium during harvesting and transportation, on the quality parameters (e.g., microbiological stability, sensory attributes, physicochemical changes) and shelf life of fish. The effect of seasonal variability of seawater temperature on fish preservation using the tested cooling media was also investigated. Gilthead sea bream (Sparus aurata) was slaughtered and transported in different mixtures of conventional flake ice and slurry ice for 24 h. Three mixtures of ice were tested as T: slaughtered in flake ice and transported in flake ice (control), TC: slaughtered in slurry ice and transported in flake ice, T50: slaughtered and transported in slurry ice 50%–flake ice 50%. Samples were subsequently stored isothermally at 0 °C for shelf-life evaluation. Three independent experiments were performed at three different periods, i.e., January, April, and September, referring to a sea water temperature range of 13.3–26.8 °C. Higher sea water temperatures at catching led to lower microbial growth rates and proteolytic enzyme activities and longer shelf life of refrigerated whole fish. The partial replacement of conventional flake ice with slurry ice improved the quality and extended the shelf life of fish at 0 °C by 2–7 days. The results of the study support that the use of slurry ice may enable better quality maintenance and significant shelf-life extension of whole gilthead sea bream. Full article
(This article belongs to the Special Issue Marine Fish and Invertebrate Aquaculture)
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31 pages, 7943 KiB  
Article
Feedback between Basin Morphology and Sediment Transport at Tidal Inlets: Implications for Channel Shoaling
by Douglas R. Krafft, Richard Styles and Mitchell E. Brown
J. Mar. Sci. Eng. 2022, 10(3), 442; https://doi.org/10.3390/jmse10030442 - 18 Mar 2022
Cited by 1 | Viewed by 1691
Abstract
Increasing societal pressures (e.g., population growth and urbanization) are driving land use change practices in coastal areas that could potentially alter the hydrodynamics and sediment transport patterns near coastal inlets in ways that might exacerbate existing shoaling conditions. To investigate the potential impact [...] Read more.
Increasing societal pressures (e.g., population growth and urbanization) are driving land use change practices in coastal areas that could potentially alter the hydrodynamics and sediment transport patterns near coastal inlets in ways that might exacerbate existing shoaling conditions. To investigate the potential impact of coastal development, a numerical model is used to predict the long-term evolution of an idealized lagoonal-type barrier island inlet under five different morphological conditions that transitioned from net sediment import to net sediment export. The simulations were designed to address the potential effect of inter-tidal placement and land reclamation on sediment transport and the resulting deposition/erosion patterns. Estuaries that were deeper and devoid of extensive tidal flats tended to promote sediment import and had a greater propensity to exacerbate channel shoaling. Simulations that were characteristic of inter-tidal placement showed net export, yet the likelihood of channel shoaling was increased because some of the material eroded from the tidal flats was deposited in the deeper channels as opposed to being carried out the inlet throat. Alternatively, it was found that regions in which the intertidal area was restricted to elevations higher in the tidal frame, which also showed a net export, produced greater sediment loss in the inter-tidal zone that tended to bypass the deeper sections, reducing the likelihood of channel shoaling. Full article
(This article belongs to the Special Issue Selected Papers from the 16th Estuarine and Coastal Modeling Conference)
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18 pages, 2189 KiB  
Article
Estimation of Total Suspended Matter Concentration of Ha Long Bay, Vietnam, from Formosat-5 Image
by Pham-Minh Chau and Chi-Kuei Wang
J. Mar. Sci. Eng. 2022, 10(3), 441; https://doi.org/10.3390/jmse10030441 - 18 Mar 2022
Cited by 1 | Viewed by 1952
Abstract
This study proposes the use of spatial high-resolution Formosat-5 (FS5) images for estimating total suspended matter (TSM) concentrations in a coastal region. Although many atmospheric correction methods are available, none of them are proposed to apply to FS5. Therefore, to remove the atmospheric [...] Read more.
This study proposes the use of spatial high-resolution Formosat-5 (FS5) images for estimating total suspended matter (TSM) concentrations in a coastal region. Although many atmospheric correction methods are available, none of them are proposed to apply to FS5. Therefore, to remove the atmospheric effect, we performed a linear regression between the digital number (DN) of an FS5 image and the Landsat-8 Operational Land Imager (OLI) level-2 remote-sensing reflectance (Rrs) by using 160 samples of five ground targets. The ground targets, namely roof material, asphalt, water, vegetation, and other materials (sand and soil), were assumed to have negligible differences within 24 h. The results show that the linear model used for computing FS5 reflectance exhibited good coefficients of determination (R2) ranging from 0.87 to 0.96 for blue, green, red, and near-infrared bands. Next, in situ TSM measurements were not collected during the FS5 overpassing in Ha Long Bay, Vietnam, so we used two existing algorithms with a red band to estimate the TSM concentration. These algorithms developed for different coastal waters exhibited satisfactory agreement between derived field data and observed TSM concentrations with R2 ranging from 0.86 to 0.95. We also cross-checked the accuracy of the FS5-derived TSM concentration through comparison with an OLI-derived TSM image. The OLI-derived TSM image was validated and discussed for Vietnamese coastal waters, including Ha Long Bay. Lastly, based on comparisons between FS5- and OLI-derived TSM images in terms of spatial distribution, histograms, and root mean square error, we indicated the FS5 images after the removal of atmospheric effects could be totally used for estimating TSM in coastal water regions. Full article
(This article belongs to the Special Issue Satellite Monitoring of Ocean)
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15 pages, 2759 KiB  
Article
Hydrodynamic Performance of Full-Scale T0 and T90 Codends with and without a Codend Cover
by Zhaohai Cheng, Paul D. Winger, Shannon M. Bayse and David Kelly
J. Mar. Sci. Eng. 2022, 10(3), 440; https://doi.org/10.3390/jmse10030440 - 18 Mar 2022
Cited by 13 | Viewed by 2306
Abstract
The hydrodynamic performance of one full-scale T0 (mesh size 90 mm) and three T90 (mesh size 90, 100, and 110 mm) codends was investigated and compared using flume tank testing, with and without a small-mesh cover. We evaluated how flow velocity, mesh circularity, [...] Read more.
The hydrodynamic performance of one full-scale T0 (mesh size 90 mm) and three T90 (mesh size 90, 100, and 110 mm) codends was investigated and compared using flume tank testing, with and without a small-mesh cover. We evaluated how flow velocity, mesh circularity, and drag changed in each codend at five different towing speeds (0.5–0.9 m/s). The results demonstrated that flow velocity decreased along the length of a codend, and this effect was pronounced in the T0 codend. Increasing the mesh size of T90 codends from 90 to 110 mm did not significantly affect flow velocity. A novel parameter, termed mesh circularity, was developed and introduced to describe mesh opening. Mesh circularity in the T0 codend decreased along the length of the codend, which contrasted with the T90 codends. Results showed that the T90 codends maintained relatively open meshes (circularity ranged from ~0.8 to 1.0 along the length of the codend) compared to the T0 (circularity ranged from ~0.6 to 0.4). Each T90 codend had a significantly (p < 0.05) higher drag than the T0 codend when using the same simulated catch. For the covered codend comparisons, the flow velocity in the area between codend and cover did not change for the T0 codend (p > 0.05), but was significantly different for the T90 codend (p < 0.05). The results of this research provide fundamental knowledge useful for understanding and improving selectivity of trawls in marine fisheries, especially for revealing the masking effects of the cover net on the codend. Full article
(This article belongs to the Section Ocean Engineering)
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13 pages, 1775 KiB  
Article
Using an Adaptive Neuro-Fuzzy Inference System to Predict Dilution Characteristics of Vertical Buoyant Jets Subjected to Lateral Confinement
by Yufeng Zhao, Junshi He, Xiaohui Yan and Jianwei Liu
J. Mar. Sci. Eng. 2022, 10(3), 439; https://doi.org/10.3390/jmse10030439 - 18 Mar 2022
Cited by 1 | Viewed by 1728
Abstract
In order to predict the dilution characteristics of vertical buoyant jets constrained by lateral obstructions, we propose a new method based on a commonly used machine learning algorithm: the adaptive neuro-fuzzy inference system (ANFIS). By using experimental data to train and test the [...] Read more.
In order to predict the dilution characteristics of vertical buoyant jets constrained by lateral obstructions, we propose a new method based on a commonly used machine learning algorithm: the adaptive neuro-fuzzy inference system (ANFIS). By using experimental data to train and test the ANFIS model, this study shows that it had better performance than commonly used empirical equations for laterally confined jets and another artificial intelligence technique—genetic programming. The RMSE values of the ANFIS-based model were lower, and the R2 values were higher, compared with those of the empirical equation and genetic programming models. The reduction in RMSE achieved by using ANFIS to replace the empirical equations or genetic programming algorithm exceeded 20%. This research confirms that the ANFIS technique has real potential in the development of effective and accurate models that can be used to estimate the dilution characteristics of a vertical buoyant jet subjected to lateral confinement, providing a new avenue for the prediction of dilution characteristics using artificial intelligence techniques, which can also be utilized for other effluent mixing problems in marine systems. Full article
(This article belongs to the Special Issue Advances in Coastal Hydrodynamics and Water Quality Modeling)
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21 pages, 3041 KiB  
Article
Revisiting the Carbonate Chemistry of the Sea of Japan (East Sea): From Water Column to Sediment
by Pavel Tishchenko, Jing Zhang, Galina Pavlova, Petr Tishchenko, Sergey Sagalaev and Mariya Shvetsova
J. Mar. Sci. Eng. 2022, 10(3), 438; https://doi.org/10.3390/jmse10030438 - 17 Mar 2022
Cited by 4 | Viewed by 2187
Abstract
In this study, we investigated the carbonate system in sediments and water columns from five stations in the Sea of Japan (East Sea) (JES) during the R/V Hakuho Maru KH-10-2 research cruise in the summer of 2010. The total alkalinity (TA) and pH [...] Read more.
In this study, we investigated the carbonate system in sediments and water columns from five stations in the Sea of Japan (East Sea) (JES) during the R/V Hakuho Maru KH-10-2 research cruise in the summer of 2010. The total alkalinity (TA) and pH were measured. Adopting a saturation degree of 91% and 80% for the lysocline depth and calcite compensation depth (CCD), respectively, we found that those depths corresponded to 1360 and 1980 m. A comparison of the calcite saturation depths, lysocline depths, and CCD depths obtained for 1999 and 2010 suggests that acidification of the interior of the JES occurred. Sediment cores were retrieved using a multi-corer. In the sediment cores, a sharp decrease in the pH by 0.3–0.4 pH units was observed in the subsurface horizons (0–10 cm) compared with the pH of the seawater from the bottom horizons. The TA in the porewaters was significantly higher than that in the overlying seawater. The anaerobic degradation of organic matter is probably the main cause for the increasing TA in the sediments. The porewaters were significantly undersaturated with calcite and aragonite, except in that from the shallowest station, where the sediments below 7.5 cm were saturated, and even supersaturated, with calcite and aragonite. A linear correlation between the dissolved inorganic carbon and the TA for sediments with a slope of 0.9993 was found, despite there being potentially different ways for the diagenesis of the organic matter to occur. The diagenesis of organic matter in the top sediments of the JES forms gradients of TA and CO2* concentrations on the interface of “bottom water–sediments”. Averaged fluxes of TA and dissolved inorganic carbon (DIC) from the sediments to the bottom waters estimated by means of Fickian diffusion were calculated as 44 and 89 mmol/(m2 year) for TA and DIC, respectively. Full article
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18 pages, 37687 KiB  
Article
Experimental Study on Silty Seabed Liquefaction and Its Impact on Sediment Resuspension by Random Waves
by Jiangfeng Dong, Jishang Xu, Guangxue Li, Anlong Li, Shaotong Zhang, Jianwei Niu, Xingyu Xu and Lindong Wu
J. Mar. Sci. Eng. 2022, 10(3), 437; https://doi.org/10.3390/jmse10030437 - 17 Mar 2022
Cited by 5 | Viewed by 2261
Abstract
Seabed liquefaction and sediment resuspension under wave loading are key issues in marine engineering, but are usually regarded as independent processes (instead of coexisting and interacting processes). Here, we analyzed random wave-induced seabed liquefaction and its impact on sediment resuspension using flume experiments. [...] Read more.
Seabed liquefaction and sediment resuspension under wave loading are key issues in marine engineering, but are usually regarded as independent processes (instead of coexisting and interacting processes). Here, we analyzed random wave-induced seabed liquefaction and its impact on sediment resuspension using flume experiments. Results show that in a nonliquefaction scenario, excess pore pressure in the seabed oscillates with wave fluctuations, but pressure accumulation is low, while a consistent upward pressure gradient promotes sediment suspension. Wave-induced shear stress was the key driver of sediment resuspension in a nonliquefaction scenario. In the liquefied state, waves with different amplitudes differently responded to excess pore pressure; small-amplitude waves accumulated pressure, while large-amplitude waves dissipated it. Liquefied soil formed mud waves, creating elliptical motion along with random waves. Seabed liquefaction accelerated sediment resuspension in the following ways: reducing soil critical shear stress; forming seepage channels inside the seabed; forming mud waves, resulting in increased turbulent kinetic energy; dissipating excess pore pressure and releasing porewater, expelling fine-grained sediment from the liquefied soil. Our study reveals the variation in excess pore pressure in silty seabed under random waves and its effect on sediment resuspension, which is significant for understanding soil liquefaction and sediment movement of silt. Full article
(This article belongs to the Special Issue Feature Papers in Ocean Engineering)
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15 pages, 1147 KiB  
Article
Hydrogen Sulfide Production with a Microbial Consortium Isolated from Marine Sediments Offshore
by Roberto Briones-Gallardo, Muriel González-Muñoz, Itza García-Bautista, David Valdés-Lozano, Tanit Toledano-Thompson, Erik Polanco-Lugo, Renata Rivera-Madrid and Ruby Valdez-Ojeda
J. Mar. Sci. Eng. 2022, 10(3), 436; https://doi.org/10.3390/jmse10030436 - 17 Mar 2022
Cited by 5 | Viewed by 2195
Abstract
Hydrogen, electric energy production, and metal toxic bioremediation are some of the biotechnological applications of sulfate-reducing organisms, which potentially depend on the sulfide produced. In this study, offshore of Yucatan, the capacity to produce hydrogen sulfide using microbial consortia from marine sediment (SC469, [...] Read more.
Hydrogen, electric energy production, and metal toxic bioremediation are some of the biotechnological applications of sulfate-reducing organisms, which potentially depend on the sulfide produced. In this study, offshore of Yucatan, the capacity to produce hydrogen sulfide using microbial consortia from marine sediment (SC469, PD102, SD636) in batch reactors was evaluated. Kinetic tests were characterized by lactate oxidation to acetate, propionate, CO2 and methane. The inoculum SC469, located in open-ocean, differed strongly in microbial diversity and showed better performance in substrate utilization with the highest hydrogen sulfide production (246 mmolg−1 VSS) at a specific hydrogen sulfide rate of 113 mmol g−1 VSS d−1 with a 0.79 molar ratio of sulfate/lactate. Sulfate-reducing microbial consortia enriched in the laboratory from marine sediments collected offshore in Yucatan and with a moderate eutrophication index, differed strongly in microbial diversity with loss of microorganisms with greater capacity for degradation of organic macromolecules. The sulfate-reducing microorganisms were characterized using Illumina MiSeq technology and were mainly Desulfomicrobium, Clostridium and Desulfobacter. Full article
(This article belongs to the Special Issue Regulation and Action Mechanism of Marine Microorganisms in Ecosystem)
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14 pages, 3974 KiB  
Article
Estimation of the Efficiency of Vessel Speed Reduction to Mitigate Gas Emission in Busan Port Using the AIS Database
by Donghan Woo and Namkyun Im
J. Mar. Sci. Eng. 2022, 10(3), 435; https://doi.org/10.3390/jmse10030435 - 17 Mar 2022
Cited by 4 | Viewed by 2063
Abstract
To mitigate marine atmospheric pollution causing greenhouse gas (GHG) and a threat to coastal residents’ health in dense hub port cities, the Vessel Speed Reduction (VSR) programs were implemented in the Republic of Korea. Spatial analysis of the efficiency of the VSR programs [...] Read more.
To mitigate marine atmospheric pollution causing greenhouse gas (GHG) and a threat to coastal residents’ health in dense hub port cities, the Vessel Speed Reduction (VSR) programs were implemented in the Republic of Korea. Spatial analysis of the efficiency of the VSR programs is essential to monitor and improve the present programs. In the present study, the efficiency of the VSRs from the Busan Port (BP), including North Port (NP) and Gamcheon Port (GP), were analyzed. A bottom-up activity-based approach using automatic identification system (AIS) data was introduced herein for the estimation of spatial marine gas emission in real time. The BP has implemented the VSR program since 2020; thus, this study spatially analyzed marine gas emissions in the areas in 2019 and 2020 to demonstrate the efficiency of VSR. To demonstrate the VSR programs in the aspect of the comparison of gas emissions in each year, the total annual fuel consumption in each year is divided by the total arrival ships’ GT respectively. According to the comparison of the spatial gas emission inventory between two years in the designed area, 19.2% of the annual marine gas emissions per ships’ GT in BP in 2020 were reduced with the implementation of the VSR program. The spatial analysis clearly showed the mitigation of the ships’ gas emissions along the passageway to BP. The spatial analysis of the efficiency of the VSR program will be useful basic data to reflect the local gas emission state on the improvement of the VSR program and newly established environmental regulations. Full article
(This article belongs to the Section Ocean Engineering)
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28 pages, 13976 KiB  
Article
New Insight on the Stratigraphic-Diffusive Gas Hydrate System since the Pleistocene in the Dongsha Area of the Northeastern South China Sea
by Jinan Guan, Yian Liang, Shujia Wang, Lihua Wan, Shuanshi Fan, Pibo Su, Wei Zhang and Deqing Liang
J. Mar. Sci. Eng. 2022, 10(3), 434; https://doi.org/10.3390/jmse10030434 - 16 Mar 2022
Cited by 2 | Viewed by 2013
Abstract
The stratigraphic-diffusive type of gas hydrate system is formed by microbial methane produced in a shallow slope space when flowing laterally into hydrate stable zones and is worth studying for both energy supply and academic understanding. A deposition production model matching the vertical [...] Read more.
The stratigraphic-diffusive type of gas hydrate system is formed by microbial methane produced in a shallow slope space when flowing laterally into hydrate stable zones and is worth studying for both energy supply and academic understanding. A deposition production model matching the vertical and lateral seabed morphological characteristics was constructed to show the accumulation process, layer timing sequence, and reservoir quality of the stratigraphic-diffusive hydrate system in the Dongsha slope sediments since the Pleistocene. Six representative key system factors at three selected moments (1.5 Ma, 700 ka B.P., and at present) have been exhibited during debris is continuously accumulating. The coexistence of the hydrate decomposition in the lower part and the formation in the upper part, and the uneven distribution of hydrates within the slope sediment surface are explained clearly. By comparing four geological cases with diverse environments, it is shown that the diffusive hydrate system is likely to develop into moderate geological conditions. The most powerful carbon fixation ability in this system was quantified within the time range of 100−50 ka B.P. Finally, it was verified that residual methane would converge near the seafloor interface and then eventually overflow out of the seabed into the seawater. Full article
(This article belongs to the Special Issue Marine Gas Hydrate: Geological Characterization, Resource Potential, Exploration and Development)
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17 pages, 9167 KiB  
Article
Distribution Analysis of Local Ice Pressures in the Indentation Test at Various Velocities
by Guojun Wang, Qianjin Yue, Dayong Zhang, Yanghua Fu, Xin Peng and Rui Dong
J. Mar. Sci. Eng. 2022, 10(3), 433; https://doi.org/10.3390/jmse10030433 - 16 Mar 2022
Viewed by 1603
Abstract
When sea ice acts on vertical structures, there are much higher pressures in localized areas known as high-pressure zones (HPZs) than in other areas. The damage failure mode of sea ice varies with the sea ice velocity and affects the distribution of HPZs. [...] Read more.
When sea ice acts on vertical structures, there are much higher pressures in localized areas known as high-pressure zones (HPZs) than in other areas. The damage failure mode of sea ice varies with the sea ice velocity and affects the distribution of HPZs. In this study, an indentation test that drives ice sheet interaction with a vertical rigid plate (indentor) was designed, and a pressure sensor (consisting of 32 × 32 small pressure units of 100 mm2) was installed on the indentor face to measure the local ice pressure (LIP) at various velocities. The distribution of the LIPs along the ice thickness, the probability distribution of the LIPs and the distribution relationship of the LIPS in space and time were obtained from the measurement. The results show that the LIPs were mainly distributed in the middle of the sea ice, which is consistent with full-scale observations and previous research. Ductile failure of the sea ice results in a larger LIP distribution area than brittle failure at the same threshold kt (kt = σL/σcr). The probability distribution of the LIPs decreases exponentially with increasing pressure and follows a lognormal distribution. The maximum LIP appears at the peak moment of the global force when the sea ice failure mode is mainly ductile failure. However, the maximum LIP may not occur at the peak moment when the sea ice failure is mainly brittle failure and, instead can appear at any moment in the global force time history curve. The HPZ (which is larger than 7/8 times the maximum LIP) area is less than 2% of the nominal contact area at various velocities. The influence of the sea ice velocity on the spatial and temporal distribution of LIP is analyzed, and the results provide a reference for designing structures with local strength in ice regions. Full article
(This article belongs to the Section Ocean Engineering)
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25 pages, 9817 KiB  
Article
An Efficient Method for Nested High-Resolution Ocean Modelling Incorporating a Data Assimilation Technique
by Georgy I. Shapiro and Jose M. Gonzalez-Ondina
J. Mar. Sci. Eng. 2022, 10(3), 432; https://doi.org/10.3390/jmse10030432 - 16 Mar 2022
Cited by 4 | Viewed by 2032
Abstract
A simple and computationally efficient method is presented for creating a high-resolution regional (child) model nested within a coarse-resolution, good-quality data-assimilating (parent) model. The method, named Nesting with Downscaling and Data Assimilation (NDA), reduces bias and root mean square errors (RMSE) of the [...] Read more.
A simple and computationally efficient method is presented for creating a high-resolution regional (child) model nested within a coarse-resolution, good-quality data-assimilating (parent) model. The method, named Nesting with Downscaling and Data Assimilation (NDA), reduces bias and root mean square errors (RMSE) of the child model and does not allow the child model to drift from reality. Usually coarser resolution models, e.g., global scale, are used to provide boundary conditions for the nested child model. The basic idea of the NDA method is to use a complete 3D set of output data from the parent model using a process which is similar to data assimilation of observations into an ocean model. In this way, the child model is physically aware of observations via the parent model. The method allows for avoiding a complex process of assimilating the same observations which were already assimilated into the parent model. The NDA method is illustrated in several simple 2D synthetic cases where the true solution is known. The NDA method reduces the child model bias to the same level as in the parent model and reduces the RMSE, typically by a factor of two to five, occasionally more. Full article
(This article belongs to the Special Issue Technological Oceanography)
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20 pages, 8998 KiB  
Article
Antioxidant and Anti-Colorectal Cancer Properties in Methanolic Extract of Mangrove-Derived Schizochytrium sp.
by Kaliyamoorthy Kalidasan, Laurent Dufossé, Gunasekaran Manivel, Poomalai Senthilraja and Kandasamy Kathiresan
J. Mar. Sci. Eng. 2022, 10(3), 431; https://doi.org/10.3390/jmse10030431 - 16 Mar 2022
Cited by 4 | Viewed by 2356
Abstract
This work studied the antioxidant and anti-colorectal cancer properties of a potential strain of thraustochytrids, Schizochytrium sp. (SMKK1), isolated from mangrove leaf litter. The biomass was extracted with methanol and screened for antioxidant activity using six different assays. The extract exhibited the highest [...] Read more.
This work studied the antioxidant and anti-colorectal cancer properties of a potential strain of thraustochytrids, Schizochytrium sp. (SMKK1), isolated from mangrove leaf litter. The biomass was extracted with methanol and screened for antioxidant activity using six different assays. The extract exhibited the highest total antioxidant activity (87.37 ± 1.22%) and the lowest nitric oxide radical (75.12 ± 2.22%), and the activity increased with the concentration of the extract. The methanolic extract was further tested for in vitro cytotoxicity on the colon cancer cell line (HT29). The extract was also analyzed for polyunsaturated fatty acids using GC-MS. The five predominant HTVS-based compounds, viz., arachidonic acid, linolenic acid (alpha-linolenic acid and gamma-linolenic acid), eicosapentaenoic acid, and docosahexaenoic acid, were identified in the extract, and these were tested against the colon cancer protein IGF binding (IGF-1) using the in silico docking method. The results revealed that all the five compounds were capable of destroying the colon oncoprotein responsible for anti-colon carcinogen, based on activation energy and also good hydrogen bond interaction against IGF binding proteins. Of the compounds, docosahexaenoic acid was the most effective, having a docking score of −10.8 Kcal/mol. All the five fatty acids passed the ADMET test and were hence accepted for further clinical trials towards the development of anticancer drugs. Full article
(This article belongs to the Special Issue Frontiers in Marine Microbiological Research)
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17 pages, 1820 KiB  
Article
Transcriptome Analysis of the Marine Nematode Litoditis marina in a Chemically Defined Food Environment with Stearic Acid Supplementation
by Xuwen Cao, Peiqi Sun and Liusuo Zhang
J. Mar. Sci. Eng. 2022, 10(3), 428; https://doi.org/10.3390/jmse10030428 - 16 Mar 2022
Cited by 2 | Viewed by 2457
Abstract
Stearic acid represents one of the most abundant fatty acids in the Western diet and profoundly regulates health and diseases of animals and human beings. We previously showed that stearic acid supplementation promoted development of the terrestrial model nematode Caenorhabditis elegans in chemically [...] Read more.
Stearic acid represents one of the most abundant fatty acids in the Western diet and profoundly regulates health and diseases of animals and human beings. We previously showed that stearic acid supplementation promoted development of the terrestrial model nematode Caenorhabditis elegans in chemically defined CeMM food environment. However, whether stearic acid regulates development of other nematodes remains unknown. Here, we found that dietary supplementation with stearic acid could promote the development of the marine nematode Litoditis marina, belonging to the same family as C. elegans, indicating the conserved roles of stearic acid in developmental regulation. We further employed transcriptome analysis to analyze genome-wide transcriptional signatures of L. marina with dietary stearic acid supplementation. We found that stearic acid might promote development of L. marina via upregulation of the expression of genes involved in aminoacyl-tRNA biosynthesis, translation initiation and elongation, ribosome biogenesis, and transmembrane transport. In addition, we observed that the expression of neuronal signaling-related genes was decreased. This study provided important insights into how a single fatty acid stearic acid regulates development of marine nematode, and further studies with CRISPR genome editing will facilitate demonstrating the molecular mechanisms underlying how a single metabolite regulates animal development and health. Full article
(This article belongs to the Special Issue Genetic Diversity in Marine Organisms: Assessment, Conservation and Sustainable Utilization)
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16 pages, 3966 KiB  
Article
Underwater Single-Image Restoration with Transmission Estimation Using Color Constancy
by Wenbo Zhang, Weidong Liu and Le Li
J. Mar. Sci. Eng. 2022, 10(3), 430; https://doi.org/10.3390/jmse10030430 - 15 Mar 2022
Cited by 6 | Viewed by 2082
Abstract
The issue of underwater image restoration was investigated in this paper. Specifically, the color constancy of a single image was used to estimate the transmission map (TM), which can be used in the image formation model to restore the underwater image. First, the [...] Read more.
The issue of underwater image restoration was investigated in this paper. Specifically, the color constancy of a single image was used to estimate the transmission map (TM), which can be used in the image formation model to restore the underwater image. First, the illumination component based on color constancy was used to estimate the refined TM without performing the guided filter or soft matting operation. Second, the statistical property of the pixel was used to fine-tune the color unbalance of underwater images. Finally, both qualitative and quantitative experimental results showed that the proposed method can not only obtain better restoration results, but also improve the real-time performance in different underwater scenes compared with other underwater image restoration methods. Full article
(This article belongs to the Section Physical Oceanography)
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17 pages, 6392 KiB  
Article
Numerical Simulation on the Hydrodynamic Flow Performance and an Improve Design of a Circulating Water Channel
by Can Yang, Zhibin Hao, Huaqi Yuan, Xiaodong Bai, Zuohang Su, Hailong Chen and Lars Johanning
J. Mar. Sci. Eng. 2022, 10(3), 429; https://doi.org/10.3390/jmse10030429 - 15 Mar 2022
Viewed by 1858
Abstract
A Circulating Water Channel (CWC) is an important piece of equipment for hydrodynamic tests in ocean engineering, the quality of the flow field produced by the CWC directly affects the accuracy of the experimental results. Optimizing the key parts of the CWC device [...] Read more.
A Circulating Water Channel (CWC) is an important piece of equipment for hydrodynamic tests in ocean engineering, the quality of the flow field produced by the CWC directly affects the accuracy of the experimental results. Optimizing the key parts of the CWC device can efficiently improve the velocity uniformity and helps to achieve a high-level flow performance. In this paper, a CWC flume is set up numerically, and a series of hydrodynamic tests were carried out to evaluate the flow uniformity by optimizing the turning vane and contraction section. The numerical model is solved based on the RANS equation by using the RNG model to simulate turbulence. The improved design of the CWC includes the investigations of the flow guiding vane at the turning corners and the contraction section in the flow acceleration zone. The turning vane cross-sectional shape, the straight-edged length of the wing, and the layout of the contraction transition section design were considered and verified. The obtained results show that the wing-type turning vane with appropriate straight-edged length can help to improve the velocity uniformity of the flow field. The Witozinsky transition curve could achieve better pressure gradient effects for CWC contraction section design, and the flow uniformity improved by increasing the contraction transition length. Based on the optimal design, the internal flow characteristics of the circulating water channel have been greatly improved, laying a solid foundation for wind-wave-current multifunction CWC equipment applications for future experiments. Full article
(This article belongs to the Section Coastal Engineering)
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22 pages, 32225 KiB  
Article
Zooplankton Abundance Reflects Oxygen Concentration and Dissolved Organic Matter in a Seasonally Hypoxic Estuary
by Jane B. Weinstock, Lourdes Vargas and Rachel Collin
J. Mar. Sci. Eng. 2022, 10(3), 427; https://doi.org/10.3390/jmse10030427 - 15 Mar 2022
Cited by 2 | Viewed by 2768
Abstract
Ocean deoxygenation, warming, and acidification resulting from global change and increasing nutrient inputs are major threats to marine ecosystems. Despite this, spatial and temporal patterns of oxygen availability and their impacts on marine life are understudied compared to warming and acidification, particularly in [...] Read more.
Ocean deoxygenation, warming, and acidification resulting from global change and increasing nutrient inputs are major threats to marine ecosystems. Despite this, spatial and temporal patterns of oxygen availability and their impacts on marine life are understudied compared to warming and acidification, particularly in coastal tropical ecosystems. We measured the abundance of major groups of zooplankton in the context of five covarying environmental parameters [temperature, salinity, dissolved oxygen (DO), dissolved organic matter (DOM), and chlorophyll concentration] in a tropical estuary for one year. Partial least squares demonstrated that environmental conditions explained 20% of the variation in the community and found that temperature, salinity, DO, and DOM were most important (Variable Importance in Projection [VIP] > 0.8). A generalized linear model identified depth, DO, salinity, and chlorophyll as significant main effects, and temperature and DOM were also significant via two-way interactions (p < 0.05). When examined separately, the abundance of each zooplankton group was explained by a slightly different combination of environmental factors, but in all cases DO had large, significant effects, and in most cases DOM or its interactions were also significant. These results demonstrate that the seasonal cycle of hypoxia in this system significantly impacts the abundance of major zooplankton groups and likely also recruitment of benthic fauna through impacts on meroplankton and benthic-pelagic food webs. Full article
(This article belongs to the Special Issue Thermal and Hypoxia Vulnerability in Tropical Marine Systems: Advances in Physiology, Ecology and Evolution)
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35 pages, 6686 KiB  
Review
From Surface Water to the Deep Sea: A Review on Factors Affecting the Biodegradation of Spilled Oil in Marine Environment
by Hernando Pactao Bacosa, Sheila Mae B. Ancla, Cris Gel Loui A. Arcadio, John Russel A. Dalogdog, Dioniela Mae C. Ellos, Heather Dale A. Hayag, Jiza Gay P. Jarabe, Ahl Jimhar T. Karim, Carl Kenneth P. Navarro, Mae Princess I. Palma, Rodolfo A. Romarate II, Kaye M. Similatan, Jude Albert B. Tangkion, Shann Neil A. Yurong, Jhonamie A. Mabuhay-Omar, Chihiro Inoue and Puspa L. Adhikari
J. Mar. Sci. Eng. 2022, 10(3), 426; https://doi.org/10.3390/jmse10030426 - 15 Mar 2022
Cited by 14 | Viewed by 9922
Abstract
Over the past century, the demand for petroleum products has increased rapidly, leading to higher oil extraction, processing and transportation, which result in numerous oil spills in coastal-marine environments. As the spilled oil can negatively affect the coastal-marine ecosystems, its transport and fates [...] Read more.
Over the past century, the demand for petroleum products has increased rapidly, leading to higher oil extraction, processing and transportation, which result in numerous oil spills in coastal-marine environments. As the spilled oil can negatively affect the coastal-marine ecosystems, its transport and fates captured a significant interest of the scientific community and regulatory agencies. Typically, the environment has natural mechanisms (e.g., photooxidation, biodegradation, evaporation) to weather/degrade and remove the spilled oil from the environment. Among various oil weathering mechanisms, biodegradation by naturally occurring bacterial populations removes a majority of spilled oil, thus the focus on bioremediation has increased significantly. Helping in the marginal recognition of this promising technique for oil-spill degradation, this paper reviews recently published articles that will help broaden the understanding of the factors affecting biodegradation of spilled oil in coastal-marine environments. The goal of this review is to examine the effects of various environmental variables that contribute to oil degradation in the coastal-marine environments, as well as the factors that influence these processes. Physico-chemical parameters such as temperature, oxygen level, pressure, shoreline energy, salinity, and pH are taken into account. In general, increase in temperature, exposure to sunlight (photooxidation), dissolved oxygen (DO), nutrients (nitrogen, phosphorous and potassium), shoreline energy (physical advection—waves) and diverse hydrocarbon-degrading microorganisms consortium were found to increase spilled oil degradation in marine environments. In contrast, higher initial oil concentration and seawater pressure can lower oil degradation rates. There is limited information on the influences of seawater pH and salinity on oil degradation, thus warranting additional research. This comprehensive review can be used as a guide for bioremediation modeling and mitigating future oil spill pollution in the marine environment by utilizing the bacteria adapted to certain conditions. Full article
(This article belongs to the Special Issue Degradation of Marine Oil Pollution)
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19 pages, 2515 KiB  
Review
The Formulation, Development and Application of Oil Dispersants
by Majid D. Farahani and Ying Zheng
J. Mar. Sci. Eng. 2022, 10(3), 425; https://doi.org/10.3390/jmse10030425 - 15 Mar 2022
Cited by 15 | Viewed by 7029
Abstract
Oil spills in open waters pose a significant threat to marine life. The application of dispersant as an oil-spill response is a promising approach to minimize the environmental burden caused by these accidental events. Dispersants have been accepted and applied by many countries [...] Read more.
Oil spills in open waters pose a significant threat to marine life. The application of dispersant as an oil-spill response is a promising approach to minimize the environmental burden caused by these accidental events. Dispersants have been accepted and applied by many countries around the world as a countermeasure in responding to oil spills due to their great success and advancements in recent years. This review covers different approaches for design and development of chemical formulas of oil dispersants with the aim to improve dispersing efficiencies, followed by formulating non-chemical dispersants, which are more environmentally friendly approaches. The encouraging properties motivate scientific communities to research and develop these non-chemical-based dispersants. In general, this review intends to offer a multi-perspective overall picture of progress made in recent years to develop and apply different dispersants suitable for combating oil spills. Full article
(This article belongs to the Special Issue Reviews in Marine Environmental Science and Engineering)
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15 pages, 5219 KiB  
Article
The Effects of Sound Speed Profile to the Convergence Zone in Deep Water
by Shuanglin Wu, Zhenglin Li, Jixing Qin, Mengyuan Wang and Wen Li
J. Mar. Sci. Eng. 2022, 10(3), 424; https://doi.org/10.3390/jmse10030424 - 15 Mar 2022
Cited by 8 | Viewed by 3656
Abstract
The structure of a sound speed profile (SSP) in deep water causes refraction of sound rays and Convergence Zones (CZs) of high intensity where the rays focus at shallow depth. Study of sound field characteristics in the CZs has always been the focus [...] Read more.
The structure of a sound speed profile (SSP) in deep water causes refraction of sound rays and Convergence Zones (CZs) of high intensity where the rays focus at shallow depth. Study of sound field characteristics in the CZs has always been the focus of deep-water acoustics research. Many studies have been conducted on sound propagation in different parts of the oceans with different environments and, in this paper, the range and width of CZ is analyzed in the East Indian Ocean (EIO) and the South China Sea (SCS). Through the experimental data collected in different seasons with the propagation conditions change in the EIO and the SCS, we observe that the SSPs in different marine environments have a significant impact on the CZs of deep water. The sound channel mixing layer and isothermal layer have great effect on the CZ ranges. The water depths in the two experimental areas are similar, the range of the first CZ in the EIO is 7–8 km farther than that in the SCS, and the width of the CZs in the EIO is about 2–3 km narrower than that in the SCS. The surface mixed layer and the thermocline affect the CZ width but has little effect on the CZ range when the sound speed at the source and the bottom are practically the same. As the propagation conditions change along the seasons in the EIO, the range of the first CZ is almost the same, but the width of the CZs in the summer is about 2 km narrower than that in the spring. The water depth affects the CZ width but has little effect on the CZ range if the CZs can be formed. The different CZ characteristics between EIO and SCS are explained by both theoretical calculation and numerical simulation. The influence of the SSP structure and water depth on the CZ range are analyzed and the corresponding mechanism is explained. The research results are of great significance for underwater acoustic detection in deep sea. Full article
(This article belongs to the Special Issue Modeling Techniques for Underwater Acoustic Scattering and Propagation (including 3D Effects))
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14 pages, 4042 KiB  
Article
An Extensive Survey of Ciguatoxins on Grouper Variola louti from the Ryukyu Islands, Japan, Using Liquid Chromatography–Tandem Mass Spectrometry (LC-MS/MS)
by Naomasa Oshiro, Hiroya Nagasawa, Miharu Watanabe, Mio Nishimura, Kyoko Kuniyoshi, Naoki Kobayashi, Yoshiko Sugita-Konishi, Hiroshi Asakura, Katsunori Tachihara and Takeshi Yasumoto
J. Mar. Sci. Eng. 2022, 10(3), 423; https://doi.org/10.3390/jmse10030423 - 15 Mar 2022
Cited by 9 | Viewed by 2616
Abstract
Ingesting fish contaminated with ciguatoxins (CTXs) originating from epibenthic dinoflagellates causes ciguatera fish poisoning (CFP). CFP occurs mainly in the tropical and subtropical Indo–Pacific region and the Caribbean Sea. Furthermore, it occurs sporadically in Japan, especially in the Ryukyu Islands between Taiwan and [...] Read more.
Ingesting fish contaminated with ciguatoxins (CTXs) originating from epibenthic dinoflagellates causes ciguatera fish poisoning (CFP). CFP occurs mainly in the tropical and subtropical Indo–Pacific region and the Caribbean Sea. Furthermore, it occurs sporadically in Japan, especially in the Ryukyu Islands between Taiwan and Kyushu, Japan. Variola louti is the most frequently implicated fish with a suggested toxin profile, consisting of ciguatoxin-1B and two deoxy congeners. Therefore, using the liquid chromatography–tandem mass spectrometry (LC-MS/MS), we analyzed CTXs in the flesh of 154 individuals from various locations and detected CTXs in 99 specimens (64%). In 65 fish (43%), CTX levels exceeded the Food and Drug Administration (FDA) guidance level (0.01 µg/kg). Furthermore, in four specimens (3%), the guideline level in Japan (>0.18 µg/kg) was met. Additionally, although the highest total CTX level was 0.376 µg/kg, the consumption of 180 g of this specimen was assumed to cause CFP. Moreover, only CTX1B, 52-epi-54-deoxyCTX1B, and 54-deoxyCTX1B were detected, with the relative contribution of the three CTX1B analogs to the total toxin content (35 ± 7.7 (SD)%, 27 ± 8.1%, and 38 ± 5.6%, respectively) being similar to those reported in this region in a decade ago. Subsequently, the consistency of the toxin profile in V. louti was confirmed using many specimens from a wide area. As observed, total CTX levels were correlated with fish sizes, including standard length (r = 0.503, p = 3.08 × 10−11), body weight (r = 0.503, p = 3.01 × 10−11), and estimated age (r = 0.439, p = 3.81 × 10−7) of the specimens. Besides, although no correlation was observed between condition factor (CF) and total CTX levels, a significance difference was observed (p = 0.039) between the groups of skinnier and fattier fish, separated by the median CF (3.04). Results also showed that the CF of four specimens with the highest CTX level (>0.18 µg/kg) ranged between 2.49 and 2.87, and they were skinnier than the average (3.03) and median of all specimens. Full article
(This article belongs to the Special Issue Chemistry, Toxicology and Etiology of Marine Biotoxins)
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25 pages, 7121 KiB  
Article
Understanding Effects of Permafrost Degradation and Coastal Erosion on Civil Infrastructure in Arctic Coastal Villages: A Community Survey and Knowledge Co-Production
by Min Liew, Ming Xiao, Louise Farquharson, Dmitry Nicolsky, Anne Jensen, Vladimir Romanovsky, Jana Peirce, Lilian Alessa, Christopher McComb, Xiong Zhang and Benjamin Jones
J. Mar. Sci. Eng. 2022, 10(3), 422; https://doi.org/10.3390/jmse10030422 - 15 Mar 2022
Cited by 9 | Viewed by 3299
Abstract
This paper presents the results of a community survey that was designed to better understand the effects of permafrost degradation and coastal erosion on civil infrastructure. Observations were collected from residents in four Arctic coastal communities: Point Lay, Wainwright, Utqiaġvik, and Kaktovik. All [...] Read more.
This paper presents the results of a community survey that was designed to better understand the effects of permafrost degradation and coastal erosion on civil infrastructure. Observations were collected from residents in four Arctic coastal communities: Point Lay, Wainwright, Utqiaġvik, and Kaktovik. All four communities are underlain by continuous ice-rich permafrost with varying degrees of degradation and coastal erosion. The types, locations, and periods of observed permafrost thaw and coastal erosion were elicited. Survey participants also reported the types of civil infrastructure being affected by permafrost degradation and coastal erosion and any damage to residential buildings. Most survey participants reported that coastal erosion has been occurring for a longer period than permafrost thaw. Surface water ponding, ground surface collapse, and differential ground settlement are the three types of changes in ground surface manifested by permafrost degradation that are most frequently reported by the participants, while houses are reported as the most affected type of infrastructure in the Arctic coastal communities. Wall cracking and house tilting are the most commonly reported types of residential building damage. The effects of permafrost degradation and coastal erosion on civil infrastructure vary between communities. Locations of observed permafrost degradation and coastal erosion collected from all survey participants in each community were stacked using heatmap data visualization. The heatmaps constructed using the community survey data are reasonably consistent with modeled data synthesized from the scientific literature. This study shows a useful approach to coproduce knowledge with Arctic residents to identify locations of permafrost thaw and coastal erosion at higher spatial resolution as well as the types of infrastructure damage of most concern to Arctic residents. Full article
(This article belongs to the Special Issue Interdisciplinary Approaches to Arctic Hazards and Risks)
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22 pages, 3943 KiB  
Article
Application of Radar Image Fusion Method to Near-Field Sea Ice Warning for Autonomous Ships in the Polar Region
by Tsung-Hsuan Hsieh, Bo Li, Shengzheng Wang and Wei Liu
J. Mar. Sci. Eng. 2022, 10(3), 421; https://doi.org/10.3390/jmse10030421 - 14 Mar 2022
Cited by 2 | Viewed by 2301
Abstract
Mastering the real-time dynamics of near-field sea ice is the primary condition to guaranteeing the navigation safety of autonomous ships in the polar region. In this study, a radar image fusion process combining marine radar and ice radar is proposed, which can effectively [...] Read more.
Mastering the real-time dynamics of near-field sea ice is the primary condition to guaranteeing the navigation safety of autonomous ships in the polar region. In this study, a radar image fusion process combining marine radar and ice radar is proposed, which can effectively solve the problems of redundant information and spatial registration during image fusion. Then, using the fused radar images, this study proposes a set of near-field sea ice risk assessment and warning processes applicable to both low- and high-sea-ice-concentration situations. The sea ice risk indexes in these two situations are constructed by using four variables: sea ice area, sea ice grayscale, distance between sea ice and the own-ship, and relative bearing of sea ice and the own-ship. Finally, visualization processing is carried out according to the size of the risk index values of each piece of sea ice to achieve a better near-field sea ice risk assessment and warning effect. According to the example demonstration results, through the radar image fusion process and the set of near-field sea ice risk assessment and warning processes proposed in this study, the sea ice risk distribution in the near-field area of the ship can be well obtained, which provides effective support for the assisted decision-making of autonomous navigation in the polar region. Full article
(This article belongs to the Special Issue Control Theory and Applications in Marine Autonomous Vehicles)
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19 pages, 2578 KiB  
Article
Motion Planning for an Unmanned Surface Vehicle with Wind and Current Effects
by Shangding Gu, Chunhui Zhou, Yuanqiao Wen, Changshi Xiao and Alois Knoll
J. Mar. Sci. Eng. 2022, 10(3), 420; https://doi.org/10.3390/jmse10030420 - 14 Mar 2022
Cited by 6 | Viewed by 2254
Abstract
Aiming at the problem that unmanned surface vehicle (USV) motion planning is disturbed by effects of wind and current, a USV motion planning method based on regularization-trajectory cells is proposed. First, a USV motion mathematical model is established while considering the influence of [...] Read more.
Aiming at the problem that unmanned surface vehicle (USV) motion planning is disturbed by effects of wind and current, a USV motion planning method based on regularization-trajectory cells is proposed. First, a USV motion mathematical model is established while considering the influence of wind and current, and the motion trajectory is analyzed. Second, a regularization-trajectory cell library under the influence of wind and current is constructed, and the influence of wind and current on the weight of the search cost is analyzed. Finally, derived from the regularization-trajectory cell and the search algorithm, a motion planning method for a USV that considers wind and current effects is provided. The experimental results indicate that the motion planning is closer to the actual trajectory of a USV in complex environments and that our method is highly practicable. Full article
(This article belongs to the Special Issue Data/Knowledge-Driven Behaviour Analysis for Maritime Autonomous Surface Ships)
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19 pages, 2715 KiB  
Article
Impacts of Discretization and Numerical Propagation on the Ability to Follow Challenging Square Wave Commands
by Sung Mo Koo, Henry Travis and Timothy Sands
J. Mar. Sci. Eng. 2022, 10(3), 419; https://doi.org/10.3390/jmse10030419 - 13 Mar 2022
Cited by 7 | Viewed by 2391
Abstract
This study determines the threshold for the computational rate of actuator motor controllers for unmanned underwater vehicles necessary to accurately follow discontinuous square wave commands. Motors must track challenging square-wave inputs, and identification of key computational rates permit application of deterministic artificial intelligence [...] Read more.
This study determines the threshold for the computational rate of actuator motor controllers for unmanned underwater vehicles necessary to accurately follow discontinuous square wave commands. Motors must track challenging square-wave inputs, and identification of key computational rates permit application of deterministic artificial intelligence (D.A.I.) to achieve tracking to a machine-precision degree of accuracy in direct comparison to other state-of-art approaches. All modeling approaches are validated in MATLAB simulations where the motor process is discretized at varying step-sizes (inversely proportional to computational rate). At a large step-size (fast computational rate), discrete D.A.I. shows a mean error more than three times larger than that of a ubiquitous model-following approach. Yet, at a smaller step size (slower computational rate), the mean error decreases by a factor of 10, only three percent larger than that of continuous D.A.I. Hence, the performance of discrete D.A.I. is critically affected by the sampling period for discretization of the system equations and computational rate. Discrete D.A.I. should be avoided when small step-size discretization is unavailable. In fact, continuous D.A.I. has surpassed all modeling approaches, which makes it the safest and most viable solution to future commercial applications in unmanned underwater vehicles. Full article
(This article belongs to the Special Issue Control, Guidance, Coordination, and Localization of Autonomous Marine Vehicles)
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13 pages, 3120 KiB  
Article
The Occurrence of Microplastics in Sediment Cores from Two Mangrove Areas in Southern Thailand
by Siriporn Pradit, Prakrit Noppradit, Pei-Sun Loh, Thongchai Nitiratsuwan, Thi Phuong Quynh Le, Chantha Oeurng, Che Abd Rahim Mohamed, Choon Weng Lee, Xixi Lu, Gusti Z. Anshari, Selvaraj Kandasamy and Jianjun Wang
J. Mar. Sci. Eng. 2022, 10(3), 418; https://doi.org/10.3390/jmse10030418 - 13 Mar 2022
Cited by 21 | Viewed by 4642
Abstract
Mangroves are areas that connect the land and sea, and are important to the ecosystem. They are important places for food sources and the habitat of aquatic fauna in the tidal areas. However, the existence of plastic debris poses a risk to the [...] Read more.
Mangroves are areas that connect the land and sea, and are important to the ecosystem. They are important places for food sources and the habitat of aquatic fauna in the tidal areas. However, the existence of plastic debris poses a risk to the aquatic environment. This study aimed to investigate the accumulation of microplastics (MPs) in sediment cores from two mangrove areas. The first mangrove area is in the outer section of the Songkhla lagoon (SK), while the second is in the coastal area of Pattani province (PN). Sediment core sampling was performed from SK = 8 stations and PN = 5 stations. Surface enrichment of MP was observed, especially in sediments of 0–4 cm. MPs were found throughout the depth in both areas, while fewer MPs were found in deeper sediment core layers (p < 0.05) at some stations inside the mangrove zone. Simple linear regression of the observed MPs and distance in the horizontal were found to be significant at SK within the mangrove zone with r2 = 0.79 (p < 0.05). MP fibers were the most commonly found MP type in both areas and were less than 1 mm. Blue and black MPs were the most abundant colors found in both areas. The six polymer types reported in this study comprised polyethylene, rayon, rubber, styrene, Poly (vinyl acetate), and paint. The findings of the present study suggest that long-term monitoring of marine debris along coastlines is necessary to help improve national policies and measures related to marine plastic debris. Full article
(This article belongs to the Special Issue Effect, Exposure, and Risk of Macro-, Micro-, and Nanoplastics in the Ocean)
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