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17 pages, 11527 KiB

Open AccessArticle

The Influence of Seamounts on the Enrichment of Rare Earth Elements in Sediments—A Case Study of the Marcus-Wake Seamounts in the Western Pacific Ocean

by Tinglu Xiao, Dong Xu, Tao Deng, Junyu Lin, Liming Ye, Qian Ge, Xibin Han, Yanhui Dong and Fengyou Chu

J. Mar. Sci. Eng. 2024, 12(1), 117; https://doi.org/10.3390/jmse12010117 - 7 Jan 2024

Cited by 1 | Viewed by 1434

Abstract

Deep-sea sediments enriched in rare earth elements and yttrium (REY-rich sediments) are widely distributed on the deep-sea floor, and their formation mechanism remains elusive. Although studies have recognized the link between seamounts and REY-rich sediments, in-depth analysis of the specific roles and effects [...] Read more.

Deep-sea sediments enriched in rare earth elements and yttrium (REY-rich sediments) are widely distributed on the deep-sea floor, and their formation mechanism remains elusive. Although studies have recognized the link between seamounts and REY-rich sediments, in-depth analysis of the specific roles and effects of seamounts in the formation of REY-rich sediments is lacking. In this study, we analyzed surface sediments from the Marcus-Wake Seamounts for grain size, geochemistry, and mineral composition and classified the samples into three types: samples with moderate REY content and dominated by terrestrial detritus; samples with high REY and authigenic mineral content; and samples rich in CaCO₃ but poor in REY. The REY in the sediments of the study area partly originate from Asian dust input and partly from seawater and/or pore water, and are mainly enriched in REY carrier particles including bioapatite fossils and micronodules. The amount of REY carrier particles influences the REY content in the sediments. The current field, primary productivity, weathering process, and depositional environment around seamounts are different from those of abyssal plains, which are conducive to the formation of REY-rich sediments. Strong bottom currents may exist in the southeastern direction of some large seamounts (e.g., Niulang Guyot), leading to the selective accumulation of REY-rich bioapatite fossils and micronodules, resulting in the formation of REY-rich sediments. Full article

(This article belongs to the Special Issue Tenth Anniversary of JMSE – Recent Advances and Future Perspectives)

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15 pages, 4110 KiB

Open AccessArticle

Acoustic Evidence of Shallow Gas Occurrences in the Offshore Sinú Fold Belt, Colombian Caribbean Sea

by Ana María Osorio-Granada, Bismarck Jigena-Antelo, Juan Vidal-Perez, Enrico Zambianchi, Edward G. Osorio-Granada, Cristina Torrecillas, Jeanette Romero-Cozar, Hermann Leon-Rincón, Karem Oviedo-Prada and Juan J. Muñoz-Perez

J. Mar. Sci. Eng. 2023, 11(11), 2121; https://doi.org/10.3390/jmse11112121 - 6 Nov 2023

Cited by 3 | Viewed by 1629

Abstract

High-resolution seismic analysis and bathymetry data, used in the Offshore Sinú Fold Belt (OSFB), have revealed seabed and sub-surface anomalies, which were probably caused by the presence of shallow gas within the sedimentary records. Shallow gas is widely detected by the frequent presence [...] Read more.

High-resolution seismic analysis and bathymetry data, used in the Offshore Sinú Fold Belt (OSFB), have revealed seabed and sub-surface anomalies, which were probably caused by the presence of shallow gas within the sedimentary records. Shallow gas is widely detected by the frequent presence of anomalous acoustic reflections including acoustic blanking, enhanced reflections, acoustic plumes, pockmarks, and dome structures. More than 30 anomalies that occur within a subsurface depth of ~65 m were acoustically detected within an area of 1000 km² on the continental shelf and upper continental slope, in water depths ranging from −20 to −1300 m. Moreover, a map with the spatial distribution of the gas occurrences is shown. A close relationship between the locally elevated seabed (dome structures), pockmarks, and acoustic blanking was found. Most of the active pockmarks may be closely related to the submarine path of the Uramita Fault, indicating that the gas occurrences are controlled by active faulting. The shallow gas occurrence was confirmed by the generation of authigenic carbonate and the occurrence of chemosymbiotic biological communities sampled in the area. Although there is an admixture of biogenic gas, it is believed that many of the features observed relate to thermogenic gas. The identification of these anomalies represents a useful basis for an assessment of marine geohazards and can serve as a hydrocarbon exploration tool. Full article

(This article belongs to the Special Issue Tenth Anniversary of JMSE – Recent Advances and Future Perspectives)

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13 pages, 6988 KiB

Open AccessArticle

The Use of Tunable Encapsulation for Long-Term Fouling Control

by Emily Ralston and Samantha Pringle

J. Mar. Sci. Eng. 2023, 11(10), 1947; https://doi.org/10.3390/jmse11101947 - 9 Oct 2023

Viewed by 1157

Abstract

Biofouling is a universal problem in the marine environment. Static structures and niche areas on ships, such as propellers, are not protected sufficiently by antifouling coatings. Encapsulation has previously been used as a fouling mitigation technique via application of an impermeable wrap or [...] Read more.

Biofouling is a universal problem in the marine environment. Static structures and niche areas on ships, such as propellers, are not protected sufficiently by antifouling coatings. Encapsulation has previously been used as a fouling mitigation technique via application of an impermeable wrap or bag to a fouled hull or structure when it arrives in port or on station. This experiment investigated the use of a novel semipermeable encapsulation to proactively protect propeller mimics from biofouling. Sleeves were installed over propeller mimic panels and deployed in an active, multiuse port for 20 months. The sleeves completely prevented macrofouling on the panels for up to 13 months and maintained surfaces below 5% cover for the entire experimental period. This shows improvement over traditional antifouling without negative impacts on water quality like dissolved oxygen, pH, etc. Full article

(This article belongs to the Special Issue Tenth Anniversary of JMSE – Recent Advances and Future Perspectives)

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12 pages, 1247 KiB

Open AccessArticle

The African Striped Grunt, Parapristipoma octolineatum (Valenciennes, 1833), in the Mediterranean Sea: The Third Record with Biological and Ecological Notes, and Identification Key for Haemulidae Recorded in the Mediterranean

by Francesco Tiralongo, Anna Maria Pappalardo, Sara Ignoto, Bianca Maria Lombardo, Venera Ferrito, Aitor Campos Sosa and Andrea Spinelli

J. Mar. Sci. Eng. 2023, 11(9), 1688; https://doi.org/10.3390/jmse11091688 - 27 Aug 2023

Cited by 5 | Viewed by 1588

Abstract

The Mediterranean Sea biodiversity is undergoing a rapid reshaping due to different factors, many of which are directly related to human activities (e.g., pollution, habitat destruction, overfishing and introduction of non-indigenous species). In this context, climate changes, and in particular water warming, are [...] Read more.

The Mediterranean Sea biodiversity is undergoing a rapid reshaping due to different factors, many of which are directly related to human activities (e.g., pollution, habitat destruction, overfishing and introduction of non-indigenous species). In this context, climate changes, and in particular water warming, are the main factors that favor the arrival and subsequent spread of thermophilic species, regardless of their area of origin (e.g., Red Sea, Atlantic Ocean). In this research, we report the third and eastern-most well-documented record of the thermophilic species Parapristipoma octolineatum (Valenciennes, 1833) in the Mediterranean Sea, providing new morphological, genetic, ecological and biological data on this rare species in the basin. The integrative taxonomical approach was robust and unambiguously identified the species as P. octolineatum. The specimen was a large-sized female in maturation. The first high-quality photographic illustrations of otoliths were provided. Recent direct observations of fishermen in the area suggested a species abundance increase. However, data from the Mediterranean Sea remain scarce and further efforts are needed to better understand the abundance and distribution of this species. Modified keys for a rapid color pattern-based determination of all Haemulidae species recorded in the Mediterranean Sea to date are also provided. Finally, the potential further expansion under the future prediction of climate changes of this Atlantic origin fish in the Mediterranean Sea is discussed. Full article

(This article belongs to the Special Issue Tenth Anniversary of JMSE – Recent Advances and Future Perspectives)

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21 pages, 30817 KiB

Open AccessArticle

Littoral Drift Impoundment at a Sandbar Breakwater: Two Case Studies along the Bight of Benin Coast (Gulf of Guinea, West Africa)

by Stephan K. Lawson, Keiko Udo, Hitoshi Tanaka and Janaka Bamunawala

J. Mar. Sci. Eng. 2023, 11(9), 1651; https://doi.org/10.3390/jmse11091651 - 24 Aug 2023

Cited by 1 | Viewed by 1827

Abstract

This study assessed the deposition of sediment and shoreline evolution at two newly constructed port facilities in the Bight of Benin, West Africa. Based on the Building with Nature approach, the concept of a sandbar breakwater was implemented at the study sites. The [...] Read more.

This study assessed the deposition of sediment and shoreline evolution at two newly constructed port facilities in the Bight of Benin, West Africa. Based on the Building with Nature approach, the concept of a sandbar breakwater was implemented at the study sites. The coastal system of the bight is characterized by a sand barrier-lagoon system and a uniform prevailing wave climate, making it a favorable location for this innovative port solution. The case studies were undertaken at the Port of Lomé, Togo, and the Lekki Deep Sea Port (Dangote Sea Port), Nigeria, using remotely sensed shoreline positions and the one-line coastline change model for different periods. After construction of the breakwater, we estimated that the updrift coastline at the two locations accreted in the range of 10–23 m/year and the rates of sediment deposition were estimated to be in the magnitude of 1.0–7.0 × 10⁵ m³/year. The comparative study conducted also showed that these rates could further reach a magnitude of 10⁶ m³/year at other sediment-accreting landforms within the bight. We found that these large magnitudes of longshore sediment transport generated from very oblique incident waves (10°–20°) and sediment input from rivers (in orders of 10⁶ m³/year) have enabled the realization of expected morphodynamic changes on the updrift shoreline of the ports. From these results, downdrift morphological changes should not be underestimated due to potential imbalances induced in the sedimentary budget along the coastline. Future developmental plans within the bight should also continuously aim to adopt nature-based solutions to protect the ecosystem while mitigating unforeseen implications. Full article

(This article belongs to the Special Issue Tenth Anniversary of JMSE – Recent Advances and Future Perspectives)

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24 pages, 4096 KiB

Open AccessEditor’s ChoiceArticle

Sensitivity Analysis of Modal Parameters of a Jacket Offshore Wind Turbine to Operational Conditions

by Nasim Partovi-Mehr, Emmanuel Branlard, Mingming Song, Babak Moaveni, Eric M. Hines and Amy Robertson

J. Mar. Sci. Eng. 2023, 11(8), 1524; https://doi.org/10.3390/jmse11081524 - 30 Jul 2023

Cited by 6 | Viewed by 2405

Abstract

Accurate estimation of offshore wind turbine (OWT) modal parameters has a prominent effect on the design loads, lifetime prediction, and dynamic response of the system. Modal parameters can vary during the operation of OWTs. This paper studies the variation and sensitivity analysis of [...] Read more.

Accurate estimation of offshore wind turbine (OWT) modal parameters has a prominent effect on the design loads, lifetime prediction, and dynamic response of the system. Modal parameters can vary during the operation of OWTs. This paper studies the variation and sensitivity analysis of an OWT’s modal parameters with respect to operational and environmental conditions. Three finite element models of a jacket-supported OWT at the Block Island Wind Farm are created within the OpenSees, SAP2000, and OpenFAST platforms and validated using experimental measurements. The OpenFAST model is used to simulate the modal parameters of the turbine under various wind speed, rotor speed, power, yaw angle, mean sea level, blade pitch angle, and soil spring values. The model-predicted modal parameters of the first fore–aft (FA) and side–side (SS) modes are compared to those identified from experimental measurements. Results from the simulations show that the first FA natural frequency and damping ratio mostly depend on the rotor speed and wind speed, respectively, while yaw angle and mean sea level do not have a visible effect. It is observed that there is about 8% stiffening in the first FA frequency and an aerodynamic damping of 7.5% during the operation of the OWT. Full article

(This article belongs to the Special Issue Tenth Anniversary of JMSE – Recent Advances and Future Perspectives)

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19 pages, 4380 KiB

Open AccessArticle

Softening/Hardening Damage Model and Numerical Implementation of Seabed Silt-Steel Interface in Yellow River Underwater Delta

by Peng Yu, Honghua Liu, Lin Geng, Shuai Wang, Yang Yu, Chenghao Zhu, Qi Yang, Hongjun Liu and Yong Guan

J. Mar. Sci. Eng. 2023, 11(7), 1415; https://doi.org/10.3390/jmse11071415 - 14 Jul 2023

Cited by 4 | Viewed by 1255

Abstract

The interaction between soil and structure is a research hotspot in ocean engineering, and the shear performance of interfaces is an essential factor affecting the bearing capacity of offshore structures. Taking the Yellow River Underwater Delta as the research area, the Softening/Hardening damage [...] Read more.

The interaction between soil and structure is a research hotspot in ocean engineering, and the shear performance of interfaces is an essential factor affecting the bearing capacity of offshore structures. Taking the Yellow River Underwater Delta as the research area, the Softening/Hardening damage model of the silt–steel interface and the determination method of model parameters are proposed based on the statistical damage theory. Through the interface monotonic shear test under the conditions of different normal stress, roughness and water content, the shear mechanical properties and volumetric deformation laws on the silt–steel interface are analyzed, and the damage model parameters are obtained. Finally, a FRIC subroutine for the damage model was developed based on ABAQUS. The research results indicate the following: (1) The interface between silt and steel exhibits two characteristics, softening/hardening and shear shrinkage/expansion, under different conditions. Roughness significantly impacts interfacial cohesion, while water content mainly affects the internal friction angle. (2) The softening model based on the classic rock damage model can better simulate the stress–strain relationship of the silt–steel interface under high normal stress and low water content. In contrast, the hardening model based on the classic hyperbola model can better simulate the stress–strain relationship under low normal stress and high water content. The calculated results of the softening/hardening model agree with the experimental results, and the model has 7 parameters. (3) The developed FRIC subroutine can effectively simulate the nonlinear mechanical behavior of the interface between silt and steel. The research results provide a reference for exploring the stability analysis of offshore structures considering interface weakening effects. Full article

(This article belongs to the Special Issue Tenth Anniversary of JMSE – Recent Advances and Future Perspectives)

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15 pages, 5952 KiB

Open AccessArticle

CFD Analysis of Biofouling Effect on Submarine Resistance and Wake

by I Ketut Aria Pria Utama, Fertisio Farhan, Ahmad Nasirudin, Rizky Chandra Ariesta and Martin Robert Renilson

J. Mar. Sci. Eng. 2023, 11(7), 1312; https://doi.org/10.3390/jmse11071312 - 28 Jun 2023

Cited by 1 | Viewed by 1869

Abstract

It is well known that biofouling increases a ship’s resistance and nominal wake. For submarines, any change to the circumferential variation of the nominal wake in the propeller plane will affect the variation of the flow over the propeller blade, and hence the [...] Read more.

It is well known that biofouling increases a ship’s resistance and nominal wake. For submarines, any change to the circumferential variation of the nominal wake in the propeller plane will affect the variation of the flow over the propeller blade, and hence the fluctuating forces, and noise, generated by the propeller. The ANSYS FLUENT commercial Reynolds-Averaged Navier Stokes Computational Fluid Dynamics solver was used to investigate the influence of both the longitudinal and vertical distribution of biofouling on the resistance and wake, including the circumferential variation of the nominal wake, on a submarine, using the well-known Suboff standard submarine. For the present work, the k-ε turbulence model was selected, as this is commonly used in this field and is generally considered acceptable. To handle different boundary layer thicknesses in the flow fields, the whole y+ formulation was employed, enabling automatic switching between low and high Reynolds boundary wall models. The numerical solver used for the simulations is based on the finite volume method, which discretizes the RANS equations. In this approach, a segregated model was utilized in the solver, and the convection terms were discretized using the second-order upwind scheme to enhance solution accuracy. The criteria for the near wall are between 30 and 100, and the value of y+ for the present case is 84. It is shown that fouling over only the forward third of the submarine results in a greater increase in resistance than fouling over only the aft third. Fouling over only the lower half of the submarine results in greater resistance than fouling over only the forward third, but less than fouling over the whole of the hull. Fouling over only the forward third of the hull has less influence on the circumferential variation of the wake than fouling over the aft third only of the hull. The results show the importance of keeping the forward area of the hull clean when considering resistance only, whereas keeping the aft area of the hull clean is important when considering the uniformity of the nominal wake into the propeller. Full article

(This article belongs to the Special Issue Tenth Anniversary of JMSE – Recent Advances and Future Perspectives)

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22 pages, 8611 KiB

Open AccessArticle

Computing Invasive Species Population Based on a Generalized Random Walk Process: Application to Blue Crab (Callinectes sapidus)

by Nikolaos Simantiris, Ioannis G. Violaris and Markos Avlonitis

J. Mar. Sci. Eng. 2023, 11(7), 1282; https://doi.org/10.3390/jmse11071282 - 24 Jun 2023

Cited by 3 | Viewed by 1383

Abstract

Animal population abundance is a significant parameter for studies on invasive species that can threaten the ecosystem. Researchers have been developing population estimation methods since the 18th century, in order to evaluate species’ evolution and environmental effects. However, studies on the population density [...] Read more.

Animal population abundance is a significant parameter for studies on invasive species that can threaten the ecosystem. Researchers have been developing population estimation methods since the 18th century, in order to evaluate species’ evolution and environmental effects. However, studies on the population density of the invasive species Callinectes sapidus are very limited. The present work, using a simulation model combined with field measurements, examines an innovative methodology for estimating the current population of the invasive species Callinectes sapidus in a shallow Mediterranean coastal lagoon. The methodology presented here builds the first stage of modeling and predicting the evolution of this species’ population in marine environments. The simulation model’s results are validated with an estimation of the total population based on juvenile abundance, and a curvature of the species population estimation based on cage catch is implemented. The simulation experiments presented here show the possibility of a robust prediction for blue crab population estimation. Full article

(This article belongs to the Special Issue Tenth Anniversary of JMSE – Recent Advances and Future Perspectives)

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12 pages, 8082 KiB

Open AccessArticle

Relationships between Abyssal Redox Conditions and Rock Magnetic Properties of Surficial Sediments in the Western Pacific

by Yanping Chen, Dong Xu, Huafeng Qin, Geng Liu, Yibing Li, Weiwei Chen and Liang Yi

J. Mar. Sci. Eng. 2023, 11(6), 1132; https://doi.org/10.3390/jmse11061132 - 27 May 2023

Cited by 1 | Viewed by 1358

Abstract

Reconstructing changes in deep/bottom-water redox conditions are critical for understanding the role of the deep ocean in global carbon and metals cycling; nevertheless, the quantitative relationships between redox proxies and abyssal dissolved oxygen are poorly investigated. In this work, we studied the rock [...] Read more.

Reconstructing changes in deep/bottom-water redox conditions are critical for understanding the role of the deep ocean in global carbon and metals cycling; nevertheless, the quantitative relationships between redox proxies and abyssal dissolved oxygen are poorly investigated. In this work, we studied the rock magnetic properties of surficial sediments in the western Pacific to investigate their relationship with regional redox conditions. Our results reveal a consistent sedimentary magnetic mineral assemblage in the western Pacific, dominated by pseudo-single-domain magnetite (Fe₃O₄), while the ratio of detrital and biogenic magnetite particles in different sites varies substantially. Detailed analyses identified two major magnetic-coercivity components, with modal coercivity values of 13.1 ± 1.6 mT and 54.7 ± 5.3 mT, respectively. All the magnetic parameters we measured, including both concentration-dependent and grainsize-dependent parameters, and the magnetic coercivities, are generally correlated to sedimentary redox conditions; however, the coercivities obtained by mathematical unmixing exhibit a stronger linkage, explaining about a quarter of variance of redox changes. Our findings confirm the potential of magnetic properties for tracing abyssal redox changes in the western Pacific, while the observed magnetic-redox relationships are complex and need further investigation. Full article

(This article belongs to the Special Issue Tenth Anniversary of JMSE – Recent Advances and Future Perspectives)

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14 pages, 2491 KiB

Open AccessArticle

Growth of the Mesopelagic Fish Vinciguerria attenuata (Cocco, 1838) in the Strait of Messina (Central Mediterranean Sea)

by Francesco Longo, Danilo Malara, Emanuele Asciutto and Pietro Battaglia

J. Mar. Sci. Eng. 2023, 11(5), 1055; https://doi.org/10.3390/jmse11051055 - 15 May 2023

Viewed by 1617

Abstract

The age and growth of the slender lightfish Vinciguerria attenuata are investigated for the first time by the analysis of otolith microstructure. A total of 242 individuals (standard length range = 15.3–39.0 mm) are collected from the Strait of Messina (central Mediterranean Sea). [...] Read more.

The age and growth of the slender lightfish Vinciguerria attenuata are investigated for the first time by the analysis of otolith microstructure. A total of 242 individuals (standard length range = 15.3–39.0 mm) are collected from the Strait of Messina (central Mediterranean Sea). The analysis of the length–weight relationship highlights a hyper-allometric growth for all specimens, while when males and females are analyzed separately, the results point out an isometric growth for males and hyper-allometric growth for females, although no statistical differences emerge comparing sex curves (p-value = 0.06). Microincrement readings are considered valid only for 214 sagittal otoliths. Microincrement counts range from 31 to 49 (average = 39.9) in the otolith central zone, 28 to 53 (average = 43.2) in the middle zone, and 15 to 332 (average = 136.1) in the external zone. Overall, total microincrements range between 75 and 418. Different growth models (von Bertalanffy, Gompertz and logistic models) are taken into account to select the best-fitting model in describing the growth patterns in V. attenuata. The logistic growth model is selected as the best-fitting model, and its parameters for all individuals are L_∞ = 38.597, k = 0.0104 and I = 122.4. Full article

(This article belongs to the Special Issue Tenth Anniversary of JMSE – Recent Advances and Future Perspectives)

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30 pages, 15382 KiB

Open AccessArticle

Machine Learning and Case-Based Reasoning for Real-Time Onboard Prediction of the Survivability of Ships

by Panagiotis Louvros, Fotios Stefanidis, Evangelos Boulougouris, Alexandros Komianos and Dracos Vassalos

J. Mar. Sci. Eng. 2023, 11(5), 890; https://doi.org/10.3390/jmse11050890 - 22 Apr 2023

Cited by 4 | Viewed by 2145

Abstract

The subject of damaged stability has greatly profited from the development of new tools and techniques in recent history. Specifically, the increased computational power and the probabilistic approach have transformed the subject, increasing accuracy and fidelity, hence allowing for a universal application and [...] Read more.

The subject of damaged stability has greatly profited from the development of new tools and techniques in recent history. Specifically, the increased computational power and the probabilistic approach have transformed the subject, increasing accuracy and fidelity, hence allowing for a universal application and the inclusion of the most probable scenarios. Currently, all ships are evaluated for their stability and are expected to survive the dangers they will most likely face. However, further advancements in simulations have made it possible to further increase the fidelity and accuracy of simulated casualties. Multiple time domain and, to a lesser extent, Computational Fluid dynamics (CFD) solutions have been suggested as the next “evolutionary” step for damage stability. However, while those techniques are demonstrably more accurate, the computational power to utilize them for the task of probabilistic evaluation is not there yet. In this paper, the authors present a novel approach that aims to serve as a stopgap measure for introducing the time domain simulations in the existing framework. Specifically, the methodology presented serves the purpose of a fast decision support tool which is able to provide information regarding the ongoing casualty utilizing prior knowledge gained from simulations. This work was needed and developed for the purposes of the EU-funded project SafePASS. Full article

(This article belongs to the Special Issue Tenth Anniversary of JMSE – Recent Advances and Future Perspectives)

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19 pages, 10700 KiB

Open AccessArticle

Posidonia oceanica Balls (Egagropili) from Kefalonia Island Evaluated as Alternative Biomass Source for Green Energy

by Petros Petrounias, Panagiota P. Giannakopoulou, Aikaterini Rogkala, Nikolaos Antoniou, Petros Koutsovitis, Evangelia Zygouri, Pavlos Krassakis, Ihtisham Islam and Nikolaos Koukouzas

J. Mar. Sci. Eng. 2023, 11(4), 749; https://doi.org/10.3390/jmse11040749 - 30 Mar 2023

Cited by 1 | Viewed by 3378

Abstract

Research attempts on biomass use constitute a response to the growing demand for sustainable and low-cost energy from renewable sources. Hence, the sustainable use of Posidonia oceanica (PO) waste as a material for biomass to produce green energy is being considered in many [...] Read more.

Research attempts on biomass use constitute a response to the growing demand for sustainable and low-cost energy from renewable sources. Hence, the sustainable use of Posidonia oceanica (PO) waste as a material for biomass to produce green energy is being considered in many countries in the Mediterranean region. PO meadows are considered as the main type of sea flora in the Greek coasts. PO can extract biomass from nearby ecosystems of the coastal zone, either directly through the transportation of disposed non-living leaves or indirectly via benthic organisms. The aim of this study is to investigate the use of PO waste derived from Kefalonia Island (Greece) as a biomass source. PO samples were collected around the island, and they were mineralogically and microstructurally analyzed. In addition, physicochemical, chemical, and thermogenic tests were performed in order to obtain the optimum and most completed characterization of the material. Based on the results, cellulose seems to be the main structural component of PO, which also seems to determine their behavior. PO presents microscopic similarities to other lignocellulosic materials which composition is made of carbonates, lignin, extractives, and minerals. Ash and moisture content constitute the two critical parameters that are responsible for the energy differences of each biomass. The outcome of this study shows the potential use of PO wastes as an interesting source for energy production. Full article

(This article belongs to the Special Issue Tenth Anniversary of JMSE – Recent Advances and Future Perspectives)

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21 pages, 5289 KiB

Open AccessArticle

Roving Multiple Camera Array with Structure-from-Motion for Coastal Monitoring

by Samantha Godfrey, James R. Cooper and Andrew J. Plater

J. Mar. Sci. Eng. 2023, 11(3), 591; https://doi.org/10.3390/jmse11030591 - 10 Mar 2023

Cited by 1 | Viewed by 1472

Abstract

Regular monitoring is essential for vulnerable coastal locations such as areas of landward retreat. However, for coastal practitioners, surveying is limited by budget, specialist personnel/equipment and weather. In combination structure-from-motion and multi-view stereo (SfM-MVS) has helped to improve accessibility to topographic data acquisition. [...] Read more.

Regular monitoring is essential for vulnerable coastal locations such as areas of landward retreat. However, for coastal practitioners, surveying is limited by budget, specialist personnel/equipment and weather. In combination structure-from-motion and multi-view stereo (SfM-MVS) has helped to improve accessibility to topographic data acquisition. Pole-mounted cameras with SfM-MVS have gained traction but to guarantee coverage and reconstruction quality, greater understanding of camera position and interaction is required. This study uses a multi-camera array for image acquisition and reviews processing procedures in Agisoft Photoscan (Metashape). The camera rig was deployed at three sites and results were verified against a terrestrial laser scanner (TLS) and independent precision estimates. The multi-camera approach provided effective image acquisition ~11 times faster than the TLS. Reconstruction quality equalled (>92% similarity) the TLS, subject to processing parameters. A change in the image alignment parameter demonstrated a significant influence on deformation, reducing reprojection error by~94%. A lower densification parameter (‘High’) offered results ~4.39% dissimilar from the TLS at 1/8th of the processing time of other parameters. Independent precision estimates were <8.2 mm for x, y and z dimensions. These findings illustrate the potential of multi-camera systems and the influence of processing on point cloud quality and computation time. Full article

(This article belongs to the Special Issue Tenth Anniversary of JMSE – Recent Advances and Future Perspectives)

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Review

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19 pages, 1045 KiB

Open AccessReview

A Comprehensive Review of Machine Learning for Water Quality Prediction over the Past Five Years

by Xiaohui Yan, Tianqi Zhang, Wenying Du, Qingjia Meng, Xinghan Xu and Xiang Zhao

J. Mar. Sci. Eng. 2024, 12(1), 159; https://doi.org/10.3390/jmse12010159 - 13 Jan 2024

Cited by 6 | Viewed by 8034

Abstract

Water quality prediction, a well-established field with broad implications across various sectors, is thoroughly examined in this comprehensive review. Through an exhaustive analysis of over 170 studies conducted in the last five years, we focus on the application of machine learning for predicting [...] Read more.

Water quality prediction, a well-established field with broad implications across various sectors, is thoroughly examined in this comprehensive review. Through an exhaustive analysis of over 170 studies conducted in the last five years, we focus on the application of machine learning for predicting water quality. The review begins by presenting the latest methodologies for acquiring water quality data. Categorizing machine learning-based predictions for water quality into two primary segments—indicator prediction and water quality index prediction—further distinguishes between single-indicator and multi-indicator predictions. A meticulous examination of each method’s technical details follows. This article explores current cutting-edge research trends in machine learning algorithms, providing a technical perspective on their application in water quality prediction. It investigates the utilization of algorithms in predicting water quality and concludes by highlighting significant challenges and future research directions. Emphasis is placed on key areas such as hydrodynamic water quality coupling, effective data processing and acquisition, and mitigating model uncertainty. The paper provides a detailed perspective on the present state of application and the principal characteristics of emerging technologies in water quality prediction. Full article

(This article belongs to the Special Issue Tenth Anniversary of JMSE – Recent Advances and Future Perspectives)

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