Search Results (2,637)

Underwater object detection is critical for marine resource utilization, ecological monitoring, and maritime security, yet it remains constrained by optical degradation, high energy consumption, and vulnerability to adversarial perturbations. To address these challenges, this study proposes an Adaptive Vision Transformer (A-ViT)-based detection framework. At the hardware level, a systematic power-modeling and endurance-estimation scheme ensures feasibility across shallow- and deep-water missions. Through the super-resolution reconstruction based on the Hybrid Attention Transformer (HAT) and the staged enhancement with the Deep Initialization and Deep Inception and Channel-wise Attention Module (DICAM), the image quality was significantly improved. Specifically, the Peak Signal-to-Noise Ratio (PSNR) increased by 74.8%, and the Structural Similarity Index (SSIM) improved by 375.8%. Furthermore, the Underwater Image Quality Measure (UIQM) rose from 3.00 to 3.85, while the Underwater Color Image Quality Evaluation (UCIQE) increased from 0.550 to 0.673, demonstrating substantial enhancement in both visual fidelity and color consistency. Detection accuracy is further enhanced by an improved YOLOv11-Coordinate Attention–High-order Spatial Feature Pyramid Network (YOLOv11-CA_HSFPN), which attains a mean Average Precision at Intersection over Union 0.5 (mAP@0.5) of 56.2%, exceeding the baseline YOLOv11 by 1.5 percentage points while maintaining 10.5 ms latency. The proposed A-ViT + ROI reduces inference latency by 27.3% and memory usage by 74.6% when integrated with YOLOv11-CA_HSFPN and achieves up to 48.9% latency reduction and 80.0% VRAM savings in other detectors. An additional Image-stage Attack QuickCheck (IAQ) defense module reduces adversarial-attack-induced latency growth by 33–40%, effectively preventing computational overload. Full article

Thanks to their striking shapes and colors, heterobranch “sea slugs” are probably the most sought-after group of marine critters by scuba divers around the world. Nevertheless, for many of the islands and coasts of Sicily, there are no specific studies on the fauna of this group (formerly known as opisthobranchs). Even Lampedusa, one of the most famous islands in the Mediterranean, is no exception to this. To fill this knowledge gap, the authors conducted a faunal study dedicated to this group in July 2025. Data collection, carried out using the photographic-capture technique both during scuba diving and snorkeling, led to the finding of 22 species of heterobranch “sea slugs”. A comparison of the heterobranch “sea slugs” of Lampedusa with that of other Sicilian islands revealed a low diversity of these mollusks on this island. This scarcity of fauna is probably due to the lack of favorable environments and the considerable environmental homogeneity that characterizes the seabed and coastal areas of Lampedusa. Nevertheless, the discovery of some species of considerable biogeographical importance, together with the island’s unique geographical position, make it an important location to monitor for the study of the distribution patterns of allochthonous marine Heterobranchia species that enter into the Mediterranean Sea. Full article

Underwater drones such as autonomous underwater vehicles (AUVs) and remotely operated vehicles (ROVs) are revolutionizing underwater operations and are essential for advanced marine applications like environmental monitoring, deep-sea exploration, and marine surveillance. In this paper, we concentrate on the enabling technologies and wireless communication strategies for underwater drones. Specifically, we analyze acoustic, optical, and radio frequency (RF) approaches, along with their respective advantages and disadvantages. We investigate the potential of integrating underwater drone-enabled wireless communication systems for smart marine communications. The study highlights the benefits of combining acoustic, optical, and RF methods to improve connectivity and data reliability. A hybrid underwater communication system is ideal for underwater drones because it can reduce latency, increase data throughput, and improve adaptability under various underwater conditions, supporting smart marine communications. The future direction involves developing hybrid communication frameworks that incorporate the Internet of Underwater Things (IoUT), AI-driven data, virtual reality (VR), and digital twin (DT) technologies, enabling a next-generation smart marine ecosystem. Full article

This study evaluated the feasibility of culturing Seriola lalandi in a low-cost recirculating aquaculture system (RAS) in an arid region of northern Chile, aiming to establish strategies for broodstock farming and diversify national aquaculture. The system was designed as a low-cost recirculating aquaculture system (RAS) built with locally available materials, such as galvanized corrugated steel panels and flexible plastic liners, instead of specialized aquaculture tanks. Its modular configuration, based on gravity-fed filtration using sedimentation, sand, and disc filters, allows efficient water reuse with minimal energy consumption and a daily water turnover of 12 times the total volume. This design significantly reduced construction and operational costs, making it a feasible option for aquaculture development in arid regions with limited water resources. Over an 8-month period, 46 S. lalandi individuals were used, and the results showed successful physiological adaptation of the specimens to confinement, as evidenced by low mortality, progressive acceptance of formulated feed, and sustained growth. Individual weights progressively increased, with averages ranging from 675 to 1435 g, and the specific growth rate (SGR) fluctuated between 0.14 and 0.43% per day. Fulton’s condition factor (K) remained in an adequate range between 2.4 and 2.8, suggesting good physical condition of the sampled individuals. Water quality within the RAS system was maintained within acceptable parameters, although a strong negative correlation between temperature and dissolved oxygen was recorded (Spearman coefficient = −0.71, p < 0.001), highlighting the importance of monitoring these factors in warm environments. The lack of adequate protocols for the adaptation of marine species in arid areas, such as northern Chile, has limited aquaculture development in these regions. This study addresses this problem by assessing the feasibility of a low-cost recirculating system (RAS) for the cultivation of S. lalandi under conditions of water scarcity, with the aim of diversifying the national aquaculture in arid zones. Full article

Background/Objectives: Marine-derived bioactive peptides have been reported to possess blood pressure-regulatory effects. However, most studies have focused on the antihypertensive effects after single-dose administration, and research on long-term administration and its protective effects against hypertension-induced tissue damage remains limited. Therefore, this study aimed to investigate the long-term antihypertensive efficacy of IGTGIPGIW, a bioactive peptide derived from Hippocampus abdominalis (H. abdominalis), and its protective effects on hypertension-related tissue damage. Methods: To evaluate the blood pressure-regulatory effects, spontaneously hypertensive rats (SHRs) were orally administered a high-dose (50 mg/kg) IGTGIPGIW peptide group (H-IGTGIPGIW) for 8 weeks. Systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP) were monitored weekly. Serum levels of angiotensin II (Ang II), angiotensin-converting enzyme (ACE), and angiotensin-converting enzyme 2 (ACE2) were measured to assess the peptide’s regulatory effects on the renin–angiotensin system. Histological analyses of the aorta and heart tissues were performed to evaluate the protective effects against hypertension-induced tissue damage. Results: After 8 weeks of treatment, H-IGTGIPGIW significantly reduced SBP, DBP, and MAP compared with SHRs. Serum Ang II and ACE levels were significantly decreased, while ACE2 levels were significantly increased. Histological analyses demonstrated that IGTGIPGIW alleviated aortic wall thickening and reduced renal and cardiac tissue damage in SHR. Conclusions: IGTGIPGIW, a bioactive peptide derived from H. abdominalis, effectively regulated blood pressure by modulating serum Ang II, ACE, and ACE2 levels. Moreover, it protected against hypertension-induced aortic, renal and cardiac tissue damage, suggesting its potential as a functional ingredient for managing hypertension. Full article

Marine oil spill incidents are one of the major global marine pollution issues, which pose significant threats to ocean ecosystems. However, traditional monitoring methods often suffer from time delays, high costs, and limited real-time capability, making them inadequate for timely and large-scale oil spill detection. With the development of remote sensing (RS) technology and artificial intelligence (AI) methods, as well as the increasing frequency of marine oil spill accidents, plenty of AI-based methods using RS imagery have been proposed for more efficient and accurate oil spill monitoring. This review presents a comprehensive and systematic overview of recent progress in marine oil spill analysis using RS imagery, emphasizing the integration of AI methods across three key tasks: detection, classification, and thickness estimation. Specifically, we first introduce the main types of RS data and discuss the significance of publicly available datasets, which can facilitate method validation and model comparison. Second, we briefly review the application of RS imagery from different sensors in oil spill detection, highlighting the strengths of various spectral and polarimetric methods. Third, we summarize advances in oil spill classification, including AI-based methods that enable differentiation between mineral oil, biogenic films, and various emulsified oils. Fourth, we discuss emerging techniques for oil spill thickness estimation. Finally, we analyze the challenges of existing methods and future directions, including the need for real-time monitoring, the integration of multi-source RS data, and the development of robust models that can generalize across different environmental conditions. This review adopts a comprehensive perspective from both AI methods and RS technology, provides a systematic overview of recent advancements, identifies critical gaps in current methodologies, and serves as a valuable reference for researchers and practitioners working on oil spill monitoring. Full article

Plastic waste in river systems represents a major pathway of marine pollution, with rivers estimated to contribute up to 80% of the plastic entering the ocean. This study introduces a deep learning framework with preprocessing for automated detection and tracking of floating plastic waste (macroplastics) in the urban canals of the Chao Phraya River, Thailand. Unlike previous approaches that rely on site-specific retraining or model modification, our method employs a YOLO-based detection model integrated with DeepSORT (Deep Simple Online and Realtime Tracking). The model, initially trained on laboratory flume images, was adapted to real river conditions through a three-step preprocessing pipeline comprising skew correction, background removal, and object region extraction. Experiments on 2000 canal images demonstrated that preprocessing improved the mean Average Precision (mAP) from 0.74 to 0.85, with notable gains for categories such as foam and paper. Testing with a more advanced YOLO architecture further enhanced accuracy, indicating that preprocessing and model upgrades are complementary. These findings suggest that reliable detection and quantification of floating waste can be achieved without retraining. The proposed framework provides a scalable and cost-effective solution for monitoring in data-limited regions, contributing to efforts to mitigate riverine and marine plastic pollution. Future work will address the remaining limitations, as detection performance is still influenced by strong reflections, motion blur, and occlusion, occasionally resulting in missed detections. Full article

Wall-thickness deformation is a critical indicator of fatigue risk in flexible risers exposed to vortex-induced vibration (VIV), especially under combined internal and external flow conditions. This study examines the spanwise evolution and distribution of wall-thickness deformation in a riser traversing air and water. The effects of external flow velocity, internal flow velocity, and internal fluid density on in-line (IL) and cross-flow (CF) wall deformation are systematically analyzed at characteristic positions. The results show that wall deformation exhibits strong spatial variability and media property dependence: IL deformation in the air-exposed segment is amplified under lock-in conditions due to lower damping, while the submerged segment experiences consistently larger deformation driven by added-mass effects. Internal flow influences wall-thickness response in a non-monotonic manner, and increased internal fluid density suppresses deformation while shifting the dominant frequency. These findings demonstrate that wall-thickness deformation is a sensitive and integrative response to fluid–structure interaction, offering a direct basis for identifying high-risk zones and improving fatigue-resistant design in deep-sea riser systems. Full article

With the IMO’s 2050 decarbonization target, hydrogen is a key zero-carbon fuel for shipping, but the lack of systematic risk assessment methods for hydrogen-powered marine propulsion systems (under harsh marine conditions) hinders its large-scale application. To address this gap, this study proposes an integrated risk evaluation framework by fusing Failure Mode, Effects, and Criticality Analysis (FMECA) with the Fuzzy Analytic Hierarchy Process (FAHP)—resolving the limitation of traditional single evaluation tools and adapting to the dynamic complexity of marine environments. Scientific findings from this framework confirm that hydrogen leakage, high-pressure storage tank valve leakage, and inverter overload are the three most critical failure modes, with hydrogen leakage being the primary risk source due to its high severity and detection difficulty. Further hazard matrix analysis reveals two key risk mechanisms: one type of failure (e.g., insufficient hydrogen concentration) features “high severity but low detectability,” requiring real-time monitoring; the other (e.g., distribution board tripping) shows “high frequency but controllable impact,” calling for optimized operations. This classification provides a theoretical basis for precise risk prevention. Targeted improvement measures (e.g., dual-sealed valves, redundant cooling circuits, AI-based regulation) are proposed and quantitatively validated, reducing the system’s overall risk value from 4.8 (moderate risk) to 1.8 (low risk). This study’s core contribution lies in developing a universally applicable scientific framework for marine hydrogen propulsion system risk assessment. It not only fills the methodological gap in traditional evaluations but also provides a theoretical basis for the safe promotion of hydrogen shipping, supporting the scientific realization of the IMO’s decarbonization goal. Full article

Coral reef microbial communities play pivotal roles in ecosystem functioning but remain understudied, particularly across spatial gradients and domains. Here, we use environmental DNA (eDNA) metabarcoding of 16S and 18S rRNA genes to profile bacterial and protistan communities in surface sediments from six coral reefs along the central Red Sea. At each reef, we sampled both exposed (seaward) and sheltered (shoreward) sites, enabling a multiscale analysis of diversity and community composition. We found significant differences in alpha and beta diversity between reefs and between exposure sites within reefs for both microbial groups. Redundancy analysis (RDA) and PERMANOVA revealed reef identity and exposure category as key structuring factors. Indicator species analysis and Random Forest classification identified microbial taxa predictive of exposure gradients, with several exact sequence variants (ESVs) serving as robust bioindicators in both methods. Bacterial and protistan communities exhibited overlapping but distinct patterns, highlighting their complementary ecological roles. Our results underscore the importance of fine-scale habitat heterogeneity in shaping reef microbial assemblages and support the integration of multi-domain eDNA data into coral reef monitoring frameworks. Full article

Environmental DNA (eDNA) has become a promising tool for phytoplankton surveys. However, the accuracy of eDNA-based detection is related to primer selection across diverse environments, and optimal primer pairs selection on phytoplankton community in human impacted ecosystems is still lacking. The aim of this study is to evaluate how primer selection shapes phytoplankton community profiles by eDNA biomonitoring diverse anthropogenically disturbed aquatic systems (rivers, reservoirs, and seas). Four primer pairs targeting the 18S rRNA (V9-1 and V9-2), chloroplast rbcL, and ITS regions, were explored and our results revealed that primer choice critically governed the accuracy of phytoplankton profiling. Significant variations in annotated phytoplankton eDNA sequences in different groups of primer pairs were observed, where the primers 18SV9-1 and rbcL demonstrated superior specificity, amplifying >90% of phytoplankton OTUs. 18S-targeted primers detected the highest species richness, while the ITS primer showed the lowest. Alpha diversity was highest and most consistent for 18S primers. Beta diversity ordination (nMDS/Bray–Curtis) further highlighted primer-dependent community structuring in which 18S primers effectively clustered reservoir and marine samples separately, whereas primer rbcL discriminated habitat-specific signatures across three ecosystems. The primer ITS failed to distinguish among different habitats. Overall, our data demonstrated the critical role of primer optimization in eDNA-based phytoplankton studies, and could provide methodological guidelines for the design of effective monitoring protocols in rapidly urbanizing aquatic systems. Full article

The spotted seal (Phoca largha), the only pinniped species capable of natural breeding in Chinese waters, serves as a flagship species for the Bohai Sea and the Yellow Sea marine ecosystems. Changes in its population numbers are an important indicator of the status of the marine ecological environment. However, when using traditional monitoring methods, such as telescope inspections and routine unmanned aerial vehicle (UAV) photography, it is difficult to accurately grasp the changes in spotted seal populations. Here, we document the use of infrared imaging with a UAV to facilitate round-the-clock monitoring of spotted seal numbers in a protected area. This approach revealed that late night and early morning (22:00–05:00) were peak times for their haul-out activity, with a maximum count of 166. This provides a new idea for the investigation and monitoring of marine mammals and the protection of marine ecosystems. Full article

Coastal water quality is crucial for ecosystem services, supporting biodiversity and tourism. However, high tourist influxes often overwhelm wastewater treatment plant (WWTP) capacities, leading to untreated discharge and eutrophication, which severely impacts bathing water. Water quality monitoring is currently limited to selected points at the beach and oceanographic sampling, which requires depths >20 m offshore, leaving a gap of measurements between 1 and 50 m from the beach. To resolve this gap, our study proposes a low cost-effective sampling and monitoring method by using a kayak with a submersible fluorometer FlowCAM, as well as fecal bacteria detection and quantification. The kayak sampling was carried out during high- and low-tourism seasons in coastal bathing waters surrounded by Marine Protected Areas. The results show a patchy phytoplankton distribution, with chlorophyll a concentration up to 5.5 μg/L, indicating local fertilization. The observed floating organic matter patches were fecal bacteria free, while effluents of the WWTP to the Jate river and shore exceeded the legal limits for bathing water. These results suggest that wastewater treatment was overwhelmed during the high-tourism season, likely discharging wastewater into the river that flows into the shore. These findings are discussed in a sustainable development and socioeconomical context. Full article

Background: The Kingdom of Saudi Arabia is adjacent to two vital marine ecosystems; the semi-enclosed Arabian Gulf and the largely landlocked Red Sea. Dinoflagellates are repeatedly found in these bodies of marine water, which serve as significant routes for cargo ships. Through these ships and ballast water, invasive dinoflagellate species and their cysts are introduced. They compete with indigenous species for nutrients and space, cause massive fish kill-off and disturb the ecological balance and biodiversity. To address these threats, the International Convention for the Control and Management of Ships’ Ballast Water and Sediments (BWM Convention) set forth guidelines intended to curtail the dissemination of such detrimental organisms. The Kingdom of Saudi Arabia was one of the co-signatory countries to this Convention. Methods of detection and monitoring include microscopy, molecular characterization and remote sensing, which are employed for the detection and monitoring of these harmful algae, in order to avert disasters such as fish die-offs. The results of several reports confirmed the presence of number of dinoflagellates in both the Arabian Gulf and the Red Sea, some of which are toxin producers, with certain species being highlighted as invasive species whose presence requires a high level of alert. Discussion: The monitoring, the change in engineering of cargo ships and the introduction of advanced surveillance methods, together with the proper treatments of ballast water, are all important security elements that ensure the safe disposal of ballast water without introducing harmful species. Full article

Storm surge dynamics in coastal zones and estuaries are complex, driven by coupled oceanic and terrestrial interactions that enhance the risk of coastal disasters. This study investigates storm surge characteristics and mechanisms in the Macao Cross Tidal Channel (MCTC), located in the Macao Sea Area (MSA). A tide-surge coupled numerical model was established using the unstructured grid Finite Volume Community Ocean Model (FVCOM). The model was rigorously validated against tide gauge data from Typhoon Hato, demonstrating strong performance, with a skill score of 0.95 and a correlation coefficient exceeding 0.94. The spatiotemporal characteristics and mechanisms of storm surge dynamics in the MCTC were elucidated. The results show that the MCTC’s complex geometry induces a geometric funneling effect, which substantially amplifies the storm surge compared with adjacent locations in the estuary and open sea. During the typhoon period, coastal geomorphology affects winds, tide levels, currents, and waves, which in turn spatially and temporally modulate the storm surge. Wind is the primary driver, but its effect is modulated by nonlinear interactions with waves, including enhanced bottom friction and wave set-down. In isolation, the wind-induced component contributed approximately 106% of the peak total surge. This overestimation quantitatively highlights the critical role of nonlinear interactions, where wave-enhanced bottom friction acts as a major energy sink, and wave set-down directly suppresses the water level at the channel entrance. The individual peak contributions from atmospheric pressure and wave were approximately 5% and 17%, respectively, but these peaks occurred out of phase with the storm surge. Energy transformation analysis based on the Bernoulli principle revealed a distinct conversion from potential to kinetic energy in the constricted transverse waterway, while the longitudinal waterway exhibited a more gradual energy change. These findings enhance the mechanistic understanding of storm surges in complex, constricted estuaries and can inform targeted strategies for coastal hazard mitigation in the Macao region. Full article