Development Of Marine Resources Research Articles

Coastal ecological security assessment in Laizhou Bay, China: from the perspective of demographic-social-economic-natural complex ecosystem.

Assessment of ecological security is essential for understanding the status of bay ecosystem and developing appropriate management strategy. Based on the driving force-pressure-state-impact-response (DPSIR) model, the demographic, economic, social, and ecological data of Laizhou Bay and its three neighboring counties were selected for the period from 2015 to 2021. An ecological security evaluation index system of Laizhou Bay containing 26 indicators was established, and the weights of each indicator were determined by the methods of AHP and EWM, and a comprehensive evaluation of the ecological security of Laizhou Bay was carried out by ESI. Correlations between indicators were analyzed by the Spearman's rank coefficient of correlation. The results showed that there were significant correlations between marine conditions and indicators such as population size in the surrounding area, mariculture area, industrial and domestic wastewater discharge, and treatment rate. Overall, from 2015 to 2021, the ecological security of Laizhou Bay showed a favorable trend, from a relatively unsafe level to a generally safe level, and then to a relatively safe level. Through the comprehensive evaluation of the ecological security of Laizhou Bay, we can recognize the utilization of marine resources and ecological carrying capacity, guide the rational development and utilization of marine resources, and promote the sustainable development of the marine economy.

Multi-source remote sensing big data mining reveals cross-regional correlation between aquaculture and Enteromorpha disaster outbreaks

ABSTRACT Marine aquaculture is one of the most important marine resource utilization types, widely distributed in seashore areas. Because mass marine aquaculture development will lead to the eutrophication disaster of macroalgae blooms (green tide), it is imperative to discover the latent relationship. Inspired by the big data analysis theory, the spatiotemporal correlation change in 2017 and 2019 of the marine aquaculture and macroalgae blooms in Jiangsu Shoal in the West of the Yellow Sea and its adjacent seas were monitored and extracted respectively based on multi-source remote sensing images. Through optical and Synthetic Aperture Radar (SAR) images, the imaging characteristics of marine aquaculture in different growth cycles and sea conditions are analyzed. The relationship between the green tide and marine aquaculture harvest was explored from the early green algae distribution and spatiotemporal distribution changes. The earliest harvest area of marine aquaculture is the exact location of the outbreak of green tide. Along with the rapid reduction of aquaculture area, the distribution range of green tide gradually increased. The two showed opposite trends through many multi-source remote sensing data statistical analyses. Therefore, they have a strong correlation, which can be utilized to offer a significant value for the balance of marine environmental protection and resource development.

Fault-Tolerant Control of Autonomous Underwater Vehicle Actuators Based on Takagi and Sugeno Fuzzy and Pseudo-Inverse Quadratic Programming under Constraints.

Autonomous Underwater Vehicles (AUVs) play a significant role in ocean-related research fields as tools for human exploration and the development of marine resources. However, the uncertainty of the underwater environment and the complexity of underwater motion pose significant challenges to the fault-tolerant control of AUV actuators. This paper presents a fault-tolerant control strategy for AUV actuators based onTakagi and Sugeno (T-S) fuzzy logic and pseudo-inverse quadratic programming under control constraints, aimed at addressing potential actuator faults. Firstly, considering the steady-state performance and dynamic performance of the control system, a T-S fuzzy controller is designed. Next, based on the redundant configuration of the actuators, the propulsion system is normalized, and the fault-tolerant control of AUV actuators is achieved using the pseudo-inverse method under thrust allocation. When control is constrained, a quadratic programming approach is used to compensate for the input control quantity. Finally, the effectiveness of the fuzzy control and fault-tolerant control allocation methods studied in this paper is validated through mathematical simulation. The experimental results indicate that in various fault scenarios, the pseudo-inverse combined with a nonlinear quadratic programming algorithm can compensate for the missing control inputs due to control constraints, ensuring the normal thrust of AUV actuators and achieving the expected fault-tolerant effect.

Real-time safety risk assessment of floating offshore platforms based on on-site monitoring

Real-time safety risk assessment of in-service marine engineering structures is one of the key components for the intelligent development of marine resources. Floating platforms typically have weak modes and time-varying characteristics, and hence, traditional structural damage identification and safety assessment methods cannot be directly applied to floating platforms. The objective of this study was to achieve the real-time safety risk assessment of in-service floating platforms. First, a structural damage identification method for floating platforms was proposed based on virtual loads, and the physical parameters of the platforms were obtained through inversion of measurable data. The identification result was verified based on the lengths and stiffnesses of polyester cables, which affected the dynamic response of the floating platform. The results showed that the proposed method effectively detected the parameter changes of the platform during long-term service. Then, the neural network was used to construct a load–stress surrogate model at key positions of the floating offshore platform. This model could calculate the stresses at key positions in real time, thereby evaluating the safety risks of the platform. Lastly, a real-time safety risk assessment method for floating offshore platforms was proposed, which provides a technical solution for ensuring the safety of offshore platforms.

Analysis of Chinese Patents on Cathodic Protection by Applied Current Method in Marine Sector

The resource problem is the top priority of China's current development, while the ocean is an inexhaustible treasure. The development and utilization of marine resources has always been the key direction of development. The characteristics of offshore engineering operation equipment are: first, the scale of the platform is particularly large, and second, it is long-term in the harsh environment such as moisture and salinity [1]. Therefore, the anti-corrosion of offshore platforms is the research hotspot of relevant technicians, this paper systematically summarizes the patent application of external current in cathodic protection of anti-corrosion technology. It analyzes the patent type, affiliated institution, important applicant, application field and other related contents. The results show that enterprises prefer to actually invent devices, while scientific research institutions, universities and colleges are more about the creation of technical methods.

Effect of marine ecological compensation policy on coastal water pollution: Evidence from China based on a multiple period difference-in-differences approach

With the development and utilization of marine resources, coastal water pollution has become increasingly prominent. The marine ecological compensation (MEC) is a key measure to balance the utilization of marine resources and the protection of marine environment. This paper attempts to explore the governance effect of MEC policy on coastal water pollution. Based on panel data of coastal cities in China from 2006 to 2020, a multiple period difference-in-differences (DID) model is used to estimate the impact of MEC policy on coastal water pollution. The research results show that the coastal water pollution has decreased significantly in the polit cities after implementing the MEC policy. The governance effect of MEC policy on coastal water pollution will last for three year and cover areas within a geographical distance of 200 km. The transmission mechanisms of MEC policy on coastal water pollution are the reduction of land-based sewage, marine technological progress and optimization of industrial structure. Further, this paper provides operational suggestions for strengthening the governance effect of MEC policy on coastal water pollution.

Comparative analytical study of suction drum foundation penetration characteristics of guide frame platforms with real measurements.

A suction bucket foundation is a new type offering high construction efficiency, precise positioning, cost-effectiveness, and environmental friendliness. It has been extensively employed in marine resource development, particularly in offshore wind power and oil and gas extraction. It usually involves multiple suction bucket conduit rack platforms during offshore construction projects. Accurately predicting the sinking penetration resistance and determining the suction value is crucial during the construction of the suction bucket foundation, as it ensures the safe sinking of the platform foundation to the designated depth. This paper examines the feasibility of the suction bucket foundation's sinking, sinking penetration resistance, suction value, and self-weight penetration depth, using the offshore wind farm guiding frame platform foundation project in Yangjiang, Guangdong Province, as a basis of analysis. The measured data is analyzed using the API specification static equilibrium analysis method, ABAQUS finite element analysis, and data mining techniques. The suction drum base platform's sinking process was monitored for negative pressure and penetration resistance. These observed values were compared to theoretical and finite element calculations. Results demonstrated that the API specification's theoretical calculations and finite element analyses effectively predict sinking penetration resistance, the suction force value, and the penetration depth for self-gravitational penetration. On-site engineering data fit these theoretical calculations, and finite element analyses well. The findings from this study have enriched the engineering application database of the suction drum foundation, providing a valuable reference for the design and construction of similar projects and establishing the groundwork for further promotion and application.

CSEF-Net: Cross-Scale SAR Ship Detection Network Based on Efficient Receptive Field and Enhanced Hierarchical Fusion

Ship detection using synthetic aperture radar (SAR) images is widely applied to marine monitoring, ship identification, and other intelligent maritime applications. It also improves shipping efficiency, reduces marine traffic accidents, and promotes marine resource development. Land reflection and sea clutter introduce noise into SAR imaging, making the ship features in the image less prominent, which makes the detection of multi-scale ship targets more difficult. Therefore, a cross-scale ship detection network for SAR images based on efficient receptive field and enhanced hierarchical fusion is proposed. In order to retain more information and lighten the weight of the network, an efficient receptive field feature extraction backbone network (ERFBNet) is designed, and the multi-channel coordinate attention mechanism (MCCA) is embedded to highlight the ship features. Then, an enhanced hierarchical feature fusion network (EHFNet) is proposed to better characterize the features by fusing information from lower and higher layers. Finally, the feature map is input into the detection head with improved bounding box loss function. Using SSDD and HRSID as experimental datasets, average accuracies of 97.3% and 90.6% were obtained, respectively, and the network performed well in most scenarios.

A regional digital bathymetric model fusion method based on topographic slope: A case study of the south China sea and surrounding waters

High-resolution seafloor topography is important in scientific research and marine engineering in regard to marine resource development and environmental protection monitoring. In this study, multi-dimensional comparisons were made between GEBCO_2022, SRTM15_V2.5.5, SRTM30_PLUS, SYNBATH_V1.0, ETOPO_2022, and topo_25.1 in the South China Sea and surrounding waters (SCS). This study has found that ETOPO_2022 had the best overall accuracy and reliability. Based on the results of the model accuracy analysis and by considering the topographic slope, ETOPO_2022, GEBCO_2022, and SRTM15_V2.5.5 were weighted and fused to form a fusion model. The error of the fusion model was 94.80% concentrated in (−100–100 m). When compared with GEBCO_2022, SRTM15_V2.5.5, SRTM30_PLUS, SYNBATH_V1.0, ETOPO_2022, and topo_25.1, the RMSE was reduced by 2%, 9%, 62%, 15%, 1%, and 73%, respectively. The slope-based weighted fusion method has been shown that it can overcome the limitations of a single data source and provide a reference for timely reconstruction and updating of large-scale seafloor topography.

Research on Multibeam Line Measurement Problem Based on Iterative Algorithms

With the continuous advancement of marine resource development, an efficient and reasonable multi beam acoustic survey line design scheme is crucial for accurate sea area measurement. Firstly, in order to make the model closer to the actual complex scene, a three-dimensional coverage model was derived that comprehensively considers the relative angle between the measurement line and the normal direction of the seabed terrain slope projected on the horizontal plane, referring to the three-dimensional sound beam propagation characteristics of multi beam sound waves. Then, based on the working principle and geometric relationship of multi beam recording, a formula for calculating the recording coverage width under multi-directional slope conditions considering measurement equipment parameters was derived, and an expression for the overlap rate of adjacent measurement lines was given. In addition, different measurement lines and slope normal direction angles . Finally, based on the actual sea area situation of the rectangular area within the specific given range, iteratively traverse and set different combinations of survey lines, calculate the total length of the combination and the corresponding coverage area, and calculate the coverage rate. Select the survey line combination with the shortest total length and the highest coverage rate as the optimal solution. This article focuses on the design of multi beam acoustic survey lines and establishes a universal mathematical model to achieve optimization solutions in different practical scenarios.

Object Detection Model for Marine Organisms Based on Faster R-CNN

With the development of marine resources, image-based biological target detection technology has gradually become the core method of marine ecological monitoring. This paper adopts Faster R-CNN technology, combined with two deep learning models, VGG and ResNet50, to improve the efficiency of target detection and recognition of underwater organisms. By combining large-scale annotated seabed image datasets for training, accurate localization and recognition of biological targets in images can be achieved. Compared to ResNet50, VGG performs better in complex seabed environments, with its mAP 1.75% higher than ResNet50, indicating higher detection accuracy and robustness. Besides, this study provides a practical and feasible solution for underwater ecological monitoring, verifying the excellent performance of ResNet50 in marine biological target detection, and providing an important and reliable support tool for deep-sea scientific research and ecological protection.

New developments and trends in extended continental shelf delineation practices—An analysis of China's participation and response strategies

Rights and interests concerning the continental shelf beyond 200 nautical miles (extended continental shelf, ECS) are related to important aspects of a nation's marine utilization such as marine resource development, marine technological innovation, and the construction of marine ecological civilization. China is a country with a long coastline and has the right to delineate large areas of ECS according to the United Nations Convention on the Law of the Sea (UNCLOS). However, the process of confirming China's ECS rights under international law is particularly complicated owing to the complex maritime delineation disputes between China and its neighboring countries. From the perspective of international law, this study uses the method of historical analysis and case analysis to retrospectively explore the evolution of the international legal frameworks governing ECS and analyze its current characteristics and trends in practice. On this basis, the paper evaluates the major challenges of China's national practice in ECS delineation and puts forward suggested countermeasures for safeguarding its legitimate rights and interests related to ECS.

Impacts of Reclamation on Hydrodynamic and Suspended Sediment Transport in the Bohai Sea

AbstractSince the 1970s, extensive land reclamation has been carried out in the Bohai Sea. However, reclamation activities were prohibited in 2018. Using the MIKE3 numerical model, this study selected 1976 and 2018 as representative years before and after reclamation, respectively, and developed a highly accurate three‐dimensional hydrodynamic and sediment transport model for the Bohai Sea. The model was employed to access the effects of reclamation on tidal waves, tidal prism, residual current, tidal flux (TF), and suspended sediment flux (SSF). The results revealed that after reclamation, the amphidromic points of M2 and S2 shifted southward near Qinhuangdao, and eastward near the Yellow River estuary. The M2 amplitude in the Bohai Bay exhibited a maximum increase of 30 cm. In the Bohai Sea, the tidal prism decreased by 3.95%, suggesting a decrease in water exchange capacity. The TF in the Bohai Sea and Laizhou Bay decreased by 0.7% and 12%, respectively, while increasing by 16% in Bohai Bay and 12% in Liaodong Bay, primarily due to the variations in tidal waves. Furthermore, SSF decreased by 6% in the Bohai Sea, but increased by 125% in Bohai Bay and 114% in Laizhou Bay. The significant increase in SSF in Bohai Bay and Laizhou Bay was mainly attributed to the higher suspended sediment concentrations and the stronger residual current velocities near the Yellow River estuary. This study provides comprehensive insights into the impacts of reclamation on TF and SSF in the Bohai Sea, which could contribute to marine resource development and the planning of environmental restoration projects.

High ductility cementitious composites incorporating seawater and coral sand (SCS-HDCC) for offshore engineering: Microstructure, mechanical performance and sustainability

In support of sustainable development strategies, engineering construction on remote islands is conductive to promoting the development of marine resources and mitigating increasingly severe resource conflicts. However, marine engineering, facing extreme weather and natural disasters, necessitates concrete with high ductility, durability and crack control capacity. This study evaluates the feasibility of using seawater and coral sand instead of fresh water and river sand to prepare the high ductility cementitious composites (SCS-HDCC). The results indicate that increased coral sand substitution introduces defects and expands the aggregate-matrix interfacial zone due to its rough surface, high specific area, and low strength. Coral sand's internal curing enhances compactness and reduces harmful pores. The dual action of seawater and coral sand, SCS-HDCC matrix is more tenacious, and the damage and blockage during the fiber pull-out process becomes obvious, and the slip hardening coefficient of fiber-matrix interfacial zone increases. SCS-HDCC achieves satisfactory ductility (up to 1.18 %) with initial cracking strength of 4.18 MPa, ultimate tensile strength of 5.66 MPa, and crack width of 71.2 ± 6.74 μm, average crack spacing of 6.02 mm. The SCS-HDCCs prepared in this study offers economic and environmental benefits by reducing economic costs and carbon emissions through transporting raw materials from the continent. The research results have guiding significance for the construction of islands and reefs by SCS-HDCC.

Artificial neural network-assisted optical fiber sensor for accurately measuring salinity and temperature

The observation of seawater salinity and temperature is indispensable for sustainable development and utilization of marine resources. In this research, a simple and low-cost single-mode fiber (SMF) - no-core fiber (NCF) - SMF structure based on Mach-Zehnder interference (MZI) is proposed to measure two variables with the assistance of an artificial neural network (ANN). In contrast to traditional wavelength linear fitting, direct matching of the entire spectrum to the variables through machine learning analysis effectively improves the accuracy of the output predictions. Specifically, mean absolute errors of salinity and temperature reduce from 1.540‰ to 0.808‰ and from 1.061 ℃ to 0.154 ℃, respectively. The relaxation of the light source and the optical spectrum analyzer (OSA) requirements, the fluctuation of salinity or temperature, the disturbance of environmental parameters will all not weaken the demodulation performance of the new method. Furthermore, the accuracy of the predicted results on the new probes demonstrates the adaptability of the demodulation approach. Importantly, ANN can simultaneously demodulate two parameters from a single spectrum, avoiding the cross-sensitivity problem in traditional methods. The strategy is highly generalizable and promising to be extended to any other parameters measured by optical fiber sensors.

Impacts of crude oil on Arctic sea-ice diatoms modified by irradiance

Anthropogenic climate change is reducing ice and snow thickness in the Arctic. The loss of summer sea ice has led to increased access to Arctic waters and the development of marine resources, which raises the risk of oil spills. Thinning ice and snow also increases irradiance in the upper ocean which is predicted to increase primary productivity, disfavoring shade-adapted sea-ice algae while benefitting phytoplankton and cryopelagic taxa. Studies have confirmed the lethality of crude oil and its distillates to Arctic phytoplankton; less well-constrained are the sublethal impacts to sea-ice algae in combination with other drivers. This study investigates the combination of two drivers, crude oil exposure and irradiance, on the growth rate and maximum cell concentration of four sea-ice diatoms (Attheya septentrionalis, Fragilariopsis cylindrus, and two strains of Synedropsis hyperborea) isolated from landfast sea ice near Utqiaġvik, Alaska. Crude oil inhibition of growth was complex and dependent on species and irradiance level. A. septentrionalis was generally tolerant to crude oil exposure, but toxicity was enhanced at the highest irradiance. The cryopelagic taxon, F. cylindrus, exhibited strong growth inhibition at TPH concentrations greater than approximately 6 mg L−1. Growth rates of S. hyperborea strains were stimulated at low concentrations of oil at all light levels. A simple numerical model was used to simulate an oil spill under varying snow depths to follow composition of a mock community comprised of these four isolates across a spring season. Results highlight that the reduction of algal biomass accumulation and the community composition change following a crude oil spill are more severe in a simulated low-snow spring, due to the relative sensitivity of F. cylindrus. We show that a brighter Arctic, which is predicted to increase the relative importance of cryopelagic taxa like F. cylindrus, may render the Arctic ecosystem more vulnerable to crude oil spills.

Seabed Sediment Classification using Multifrequency Backscatter

Seabed sediment serves as an important metric for assessing marine ecosystems. Different sectors, including the development and utilization of marine resources, marine engineering, environmental research, marine fisheries, and maritime navigation safety, all depend on the classification and identification of different forms of seabed sediment. Hydrographic surveys employing Multibeam Echosounders provide information that can be used to categorize the types of seabed sediment. The data acquired during the hydrographic surveys using Multibeam Echosounders include bathymetric data and backscatter data. The backscatter data is obtained from the use of Multibeam Echosounder equipment for bathymetric data acquisition. The backscatter data from Multibeam Echosounders can be utilized for determining the classification of seabed sediment as well as for identifying seabed features. This backscatter data represents the types of sediment on the seafloor and can be used for seafloor profiling and acoustic backscatter analysis to determine the several kinds of seafloor sediment. This study uses multi-frequency mosaic backscatter data and an Artificial Neural Network (ANN) approach to classify the different types of seabed sediment in the area of Benoa Port in Bali Province. The research aims to produce a distribution map of sediment types in the study area. A training accuracy of 55% and a testing accuracy of 66% were obtained from the DNN modelling. Three out of six sediment types were identified based on these accuracy results: silty sand, gravelly sand, and sandy silt with gravel corals. According to their distribution, gravely sand had the smallest distribution (5%), while silty sand had the biggest (77%).

An experimental study on monitoring of marine sediment transport by using a 3D sediment trap

The observation and analysis of sediment transport in oceans is an important means for the protection of the marine environment, resource development, construction engineering, and element cycling. However, traditional methods of observing sediment transport are either limited by the range of the instruments used or their own observational attributes, such that they cannot be used to accurately detect and analyze the process of transport of marine sediment. A 3D sediment trap has been proposed to compensate for the shortcomings of the various monitoring tools in our team, but no mature method for the analytical inversion of the data obtained from this device has been developed to date. In this paper, we developed analytical methods to invert sediment transport processes using corrected capture efficiency, sample inversion, and transport flux analysis. Through an annular flume test, we measured the turbidity, pressure, and particle size of the water stream and substituted them into the proposed analytical equations, thus verifying the applicability of the analytical methods. We used the slice experiment of the time series of the sediment samples, to determine the validity of the sample inversion, and establish the relationship between the particle size and concentration of the captured samples. We performed restoration tests on the process of sediment transport to establish a set of methods of flux analysis based on the velocity and turbidity of flow. And finally corrected for capture efficiency by particle size. The combination of analytical methods and 3D sediment trap could provide technological support for investigating the evolution of the sea, ecological cycle, and marine engineering.

Coverage Enhancement of Light-Emitting Diode Array in Underwater Internet of Things over Optical Channels

The construction of the underwater Internet of Things (UIoT) is crucial to marine resource development, environmental observation, and tactical surveillance. The underwater optical wireless communication (UOWC) system with its large bandwidth and wide coverage facilitates the high-capacity information interconnection within the UIoT networks over short and medium ranges. To enhance the coverage characteristics of the UOWC system, an optimized lemniscate-compensated layout of light-emitting diode (LED) array is proposed in this paper, which can ameliorate the received optical power and reliability at the receiving terminal. Compared with traditional circular and rectangular layouts, the received optical power and bit error rate (BER) performance of the proposed system are analyzed based on the Monte Carlo simulation method. The analysis results show that the proposed LED array achieves a smaller peak power deviation and mean square error of the received optical power under three typical seawater environments. Furthermore, the proposed LED-array scheme supports a better BER performance of the UOWC system. For example, in turbid seawater with a transmission depth of 9.5 m, the BER of the proposed LED array layout is 1 × 10−7, which is better than the BER of 3.5 × 10−6 and 1 × 10−4 under the other two traditional light source layouts.

Preserving Community Interests in Ocean Governance towards Sustainability: An Editorial Note

It is becoming increasingly evident that the preservation of the marine environment and the sustainable development of marine resources stand as the most critical elements of global ocean governance [...]