Search Results (412)

In the medical field, magnesium (Mg) alloys have been widely used due to their excellent antibacterial properties and biodegradability. However, in the marine environment, the antibacterial effect may be greatly attenuated, and consequently, microorganisms in the ocean are likely to adhere to the surface of Mg alloys, resulting in biocorrosion damage, which is really troublesome in the maritime industry and can even be disastrous to the navy. Currently, there is a lack of research on the biocorrosion of Mg alloys that may find important applications in marine engineering. In this paper, the biocorrosion mechanism of the Mg alloy Mg-3Nd-2Gd-Zn-Zr caused by Chlorella vulgaris (C. vulgaris), a typical marine microalga, was studied. The results showed that the biomineralization process in the artificial seawater containing a low concentration of C. vulgaris cells was accelerated compared with that in the abiotic artificial seawater, leading to the deposition of CaCO₃ on the surface to inhibit the localized corrosion of the Mg alloy, whereas a high concentration of C. vulgaris cells produced a high content of organic acids at some sites through photosynthesis to significantly accelerate the surface film rupture at some sites and severe localized corrosion there, but meanwhile, it resulted in the formation of a more protective biomineralized film in the other areas to greatly alleviate the corrosion. The contradictory biocorrosion behaviors on the Mg-3Nd-2Gd-Zn-Zr alloy induced by C. vulgaris were finally explained by a mechanism proposed in the paper. Full article

Maritime corrosion is a global problem often retarded through protective coatings containing corrosion inhibitors (CIs). ZnAl layered double hydroxides (LDH) have been used to immobilize CIs, which can reduce their early leaching and, thus, foster long-term corrosion protection. However, the environmental behavior of these nanomaterials remains largely unknown, particularly in the context of global changes. The present study aims to assess the environmental behavior of four anti-corrosion nanomaterials in an ocean acidification scenario (IPCC SSP3-7.0). Three different concentrations of the nanostructured CIs (1.23, 11.11, and 100 mg L⁻¹) were prepared and maintained at 20 °C and 30 °C in artificial salt water (ASW) at two pH values, with and without the presence of organic matter. The nanomaterials’ particle size and the release profiles of Al³⁺, Zn²⁺, and anions were monitored over time. In all conditions, the hydrodynamic size of the dispersed nanomaterials confirmed that the high ionic strength favors their aggregation/agglomeration. In the presence of organic matter, dissolved Al³⁺ increased, while Zn²⁺ decreased, and increased in the ocean acidification scenario at both temperatures. CIs were more released in the presence of humic acid. These findings demonstrate the influence of the tested parameters in the nanomaterials’ environmental behavior, leading to the release of metals and CIs. Full article

Weathering steel (WS) is widely used in bridge construction due to its high corrosion resistance, durability, and low maintenance requirements. This paper reviews the performance of WS bridges in Canadian climates, focusing on the formation of protective patina, influencing factors, and long-term maintenance strategies. The protective patina, composed of stable iron oxyhydroxides, develops over time under favorable wet–dry cycles but can be disrupted by environmental aggressors such as chlorides, sulfur dioxide, and prolonged moisture exposure. Key alloying elements like Cu, Cr, Ni, and Nb enhance corrosion resistance, while design considerations—such as drainage optimization and avoidance of crevices—are critical for performance. The study highlights the vulnerability of WS bridges to microenvironments, including de-icing salt exposure, coastal humidity, and debris accumulation. Regular inspections and maintenance, such as debris removal, drainage system upkeep, and targeted cleaning, are essential to mitigate corrosion risks. Climate change exacerbates challenges, with rising temperatures, altered precipitation patterns, and ocean acidification accelerating corrosion in coastal regions. Future research directions include optimizing WS compositions with advanced alloys (e.g., rare earth elements) and integrating climate-resilient design practices. This review highlights the need for a holistic approach combining material science, proactive maintenance, and adaptive design to ensure the longevity of WS bridges in evolving environmental conditions. Full article

The expansion of global maritime activities threatens marine ecosystems and biodiversity. Collisions between ships and marine megafauna profoundly impact vulnerable species such as whales, who serve as keystone predators. However, the specific regions most heavily affected by shipping traffic and the multi-species facing collision risk remain poorly understood. Here, we analyzed global shipping data to assess the distribution of areas with high shipping pressure and identify global hotspots for whale–ship collisions. The results reveal that high-pressure habitats are primarily distributed within exclusive economic zones (EEZs), which are generally consistent with the distribution of collision hotspots. High-pressure habitats exhibit significant spatial mismatch: 32.9% of Marine Protected Areas endure high shipping stress and yet occupy merely 1.25% of protected ocean area. Additionally, 25.1% of collision hotspots (top 1% risk) affect four or more whale species, forming critical aggregation in regions like the Gulf of St. Lawrence and Northeast Asian marginal seas. Most of these high-risk areas lack protective measures. These findings offer actionable spatial priorities for implementing targeted conservation strategies, such as the introduction of mandatory speed restrictions and dynamic vessel routing in high-risk, multi-species hotspots. By focusing on critical aggregation areas, these strategies will help mitigate whale mortality and enhance marine biodiversity protection, supporting the sustainable coexistence of maritime activities with vulnerable marine megafauna. Full article

Deep-sea mining presents a critical sustainability paradox; it offers access to essential minerals for the technologies of the green transition (e.g., batteries, wind turbines, electric vehicles) yet threatens fragile marine ecosystems. As the terrestrial sources of these materials face mounting geopolitical, environmental, and ethical constraints, undersea deposits are increasingly being viewed as alternatives. However, the extraction technologies remain unproven at large scales, posing risks related to biodiversity loss, sediment disruption, and altered oceanic carbon cycles. This paper explores how deep-sea mining might be reconciled with sustainable development, arguing that its viability hinges on addressing five interdependent challenges—technological readiness, environmental protection, economic feasibility, robust governance, and social acceptability. Progress requires parallel advancements across all domains. This paper reviews the current knowledge of deep-sea resources and extraction methods, analyzes the ecological and sociopolitical risks, and proposes systemic solutions, including the implementation of stringent regulatory frameworks, technological innovation, responsible terrestrial sourcing, and circular economy strategies. A precautionary and integrated approach is emphasized to ensure that the securing of critical minerals does not compromise marine ecosystem health or long-term sustainability objectives. Full article

The marine habitats of the world’s oceans are being driven beyond their resilience. The ongoing biodiversity crisis is happening fast, within the lifespan of researchers trying to produce the information necessary for the conservation of habitats and marine ecosystems. Here, we report on the destruction of sciaphilic sessile communities and coralligenous concretions produced by the anchoring of a high-tonnage vessel inside a Marine Protected Area in Cyprus. The damage from the anchors and the chains consisted of the dislodgement of large boulders that were dragged or rolled over the seafloor, increasing the breakage and further dislodgement of more boulders; many were left upside-down. The biological communities that thrived in the dark environments below the boulders were directly exposed to high irradiance levels and went through a slow mortality and decaying process, most probably due to a combination of several deterioration agents, such as exposure to direct sunlight, predation, mucilage aggregates, and cyanobacterial blooms. The enforcement of regulatory measures for anchoring and transit in the MPA is necessary to prevent similar destruction. Given the extent of the irreversible damage to these sciaphilic communities, our study is, unfortunately, another environmental post-mortem contribution. Full article

Mapping marine habitats is fundamental for biodiversity conservation and ecosystem-based management in oceanic regions under increasing anthropogenic and climatic pressures. In the context of global initiatives—such as marine protected area expansion and international agreements—habitat mapping has become mandatory for regional and global conservation policies. It provides spatial data to delineate essential habitats, support connectivity analyses, and assess pressures, enabling ecosystem-based marine spatial planning aligned with EU directives (2008/56/EC; 2014/89/EU). Beyond biodiversity, macrophytes, rhodolith beds, and coral reefs deliver key ecosystem services—carbon sequestration, coastal protection, nursery functions, and fisheries support—essential to local socioeconomies. This systematic review (PRISMA guidelines) examined 69 peer-reviewed studies across Central-Eastern Atlantic archipelagos (Macaronesia: the Azores, Madeira, the Canaries, and Cabo Verde) and the Mid-Atlantic Ridge. We identified knowledge gaps, methodological trends, and key challenges, emphasizing the integration of cartographic, ecological, and technological approaches. Although methodologies diversified over time, the lack of survey standardization, limited ground truthing, and heterogeneous datasets constrained the production of high-resolution bionomic maps. Regional disparities persist in technology access and habitat coverage. The Azores showed the highest species richness (393), dominated by acoustic mapping in corals. Madeira was most advanced in the remote mapping of rhodoliths; the Canaries focused on shallow macrophytes with direct mapping; and Cabo Verde remains underrepresented. Harmonized protocols and regional cooperation are needed to improve data interoperability and predictive modeling. Full article

This paper systematically reviews the progress of remote-sensing technology in coastal-ecosystem health assessment. Coastal ecosystems, as transitional zones between land and ocean, play vital roles in maintaining biodiversity, carbon sequestration, and coastal protection, but currently face severe challenges from climate change and human activities. Remote-sensing technology, with its capability for large-scale, long time-series observations, has become a key tool for coastal-ecosystem health assessment. This paper analyzes the technical characteristics and advantages of optical remote sensing, radar remote sensing, and multi-source data fusion in coastal monitoring; constructs a health-assessment framework that includes water-quality indicators, vegetation and ecosystem function indicators, and human disturbance and landscape change indicators; discusses the application of advanced technologies from traditional methods to machine learning and deep learning in data processing; and demonstrates the role of multi-temporal analysis in revealing coastal-ecosystem change trends through typical case studies of mangroves, salt marshes, and coral reefs. Research indicates that, despite the enormous potential of remote-sensing technology in coastal monitoring, it still faces challenges such as sensor limitations, environmental interference, and data processing and validation. Future development should focus on advanced sensor technology, platform innovation, data-processing method innovation, and multi-source data fusion, while strengthening the effective integration of remote-sensing technology with management practices to provide scientific basis for the protection and sustainable management of coastal ecosystems. Full article

Seabob shrimp Xiphopenaeus kroyeri is under heavy capture-pressure in the western Atlantic, requiring periods of fishing suspension to protect the propagation of the species in the wild. This work aims to describe the stages of gonadal development and the ovaries of X. kroyeri in trawling in the southeastern Atlantic Ocean of Brazil associated with climatic characteristics of temperature and precipitation. In total, 3658 specimens were captured in monthly collections from March 2019 to February 2020. The female gonads were classified macroscopically and microscopically according to the maturation stage and correlated with precipitation and temperature data. Five stages of maturation were observed: immature, initial maturation, advanced maturation, mature, and spawned. The highest percentage of mature females was found in May and July, and the average size of the female cephalothorax at the first gonadal maturation was 1.7 cm. The recruitment period was observed in April, with more juveniles. Precipitation showed a negative correlation with the number of mature females. April, May, and July are essential for the life cycle of the X. kroyeri population on the coast of Espírito Santo, Brazil. The results suggest that the current closed season for the species should be reconsidered. Full article

As fundamental geophysical information, the high-precision detection of shallow water bathymetry is critical data support for the utilization of island resources and coral reef protection delimitation. In recent years, the combination of active and passive remote sensing technologies has led to a revolutionary breakthrough in satellite-derived bathymetry (SDB). Optical SDB extracts bathymetry by quantifying light–water–bottom interactions. Therefore, the apparent differences in the reflectance of different bottom types in specific wavelength bands are a core component of SDB. In this study, refined classification was performed for complex seafloor sediment and geomorphic features in coral reef habitats. A multi-model synergistic SDB fusion approach constrained by coral reef habitat classification based on the deep learning framework Mamba was constructed. The dual error of the global single model was suppressed by exploiting sediment and geomorphic partitions, as well as the accuracy complementarity of different models. Based on multispectral remote sensing imagery Sentinel-2 and the Ice, Cloud, and Land Elevation Satellite-2 (ICESat-2) active spaceborne lidar bathymetry data, wide-range and high-accuracy coral reef habitat classification results and bathymetry information were obtained for the Yuya Shoal (0–23 m) and Niihau Island (0–40 m). The results showed that the overall Mean Absolute Errors (MAEs) in the two study areas were 0.2 m and 0.5 m and the Mean Absolute Percentage Errors (MAPEs) were 9.77% and 6.47%, respectively. And R² reached 0.98 in both areas. The estimated error of the SDB fusion strategy based on coral reef habitat classification was reduced by more than 90% compared with classical SDB models and a single machine learning method, thereby improving the capability of SDB in complex geomorphic ocean areas. Full article

Marine biofouling, the process of marine microorganisms, algae, and invertebrates attaching to and forming biofilms on ship hulls, underwater infrastructure, and marine equipment in ocean environments, severely impacts shipping and underwater operations by increasing fuel consumption, maintenance costs, and corrosion risks, and by threatening marine ecosystem stability via invasive species transport. This study reports the development of a hydrogel-metal-organic framework (MOF)-quorum sensing inhibitor (QSI) antifouling coating on 304 stainless steel (SS) substrates. Inspired by mussel adhesion, a hydrophilic bionic hydrogel was first constructed via metal ion coordination. The traditional metal ion source was replaced with a zeolitic imidazolate framework-8 (ZIF-8) loaded with 2-(5H)-furanone (HF, a QSI) without altering coating formation. Physicochemical characterization using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), the Brunauer–Emmett–Teller (BET) method, and the diffraction of x-rays (XRD) confirmed successful HF loading into ZIF-8 with intact crystal structures. Antifouling tests showed HF@ZIF-8 enhanced antibacterial inhibition against Staphylococcus aureus (97.28%) and Escherichia coli (>97%) and suppressed Chromobacterium violaceum CV026 pigment synthesis at 0.25 mg/mL (sub-growth concentration). The reconstructed PG/PVP/PEI/HF@ZIF-8 coating achieved 72.47% corrosion inhibition via synergistic anodic protection and physical shielding. This work provides a novel green approach for surface antifouling and drag reduction, highlighting MOF-loaded QSIs as promising additives to enhance the antifouling performance of hydrogel coatings, anti-corrosion performance, and QSI performance for sustainable marine engineering applications. Full article

Marine atmospheric boundary-layer height (MABLH) is crucial for ocean heat, momentum, and substance transfer, affecting ocean circulation, climate, and ecosystems. Due to the unique geographical location of the South China Sea (SCS), coupled with its complex atmospheric environment and sparse ground-based observation stations, accurately determining the MABLH remains challenging. Coherent Doppler wind lidar (CDWL), as a laser-based active remote sensing technology, provides high-resolution wind profiling by transmitting pulsed laser beams and analyzing backscattered signals from atmospheric aerosols. In this study, we developed a stacking optimal ensemble model (SOEM) to estimate MABLH in the vicinity of the site by integrating CDWL measurements from a representative SCS site with ERA5 (fifth-generation reanalysis dataset from the European Centre for Medium-Range Weather Forecasts) data from December 2019 to May 2021. Based on the categorization of the total cloud cover data into weather conditions such as clear/slightly cloudy, cloudy/transitional, and overcast/rainy, the SOEM demonstrates enhanced performance with an average mean absolute percentage error of 3.7%, significantly lower than the planetary boundary-layer-height products of ERA5. The SOEM outperformed random forest, extreme gradient boosting, and histogram-based gradient boosting models, achieving a robustness coefficient ($R^2$) of 0.95 and the lowest mean absolute error of 32 m under the clear/slightly cloudy condition. The validation conducted in the coastal city of Qingdao further confirmed the superiority of the SOEM in resolving meteorological heterogeneity. The predictions of the SOEM aligned well with CDWL observations during Typhoon Sinlaku (2020), capturing dynamic disturbances in MABLH. Overall, the SOEM provides a precise approach for estimating convective boundary-layer height, supporting marine meteorology, onshore wind power, and coastal protection applications. Full article

Erosion poses significant threats to infrastructures and ecosystems, exacerbated by climate change-driven sea-level rise and intensified wave actions. Microbially induced calcium carbonate precipitation (MICP) has emerged as a promising, sustainable, and eco-friendly solution for erosion mitigation. This review synthesizes recent advancements in optimizing biomineralization efficiency, multi-scale erosion control, and field-scale MICP implementations in marine dynamic conditions. Key findings include the following: (1) Kinetic analysis of Ca²⁺ conversion confirmed complete ion utilization within 24 h under optimized PA concentration (3%), resulting in a compressive strength of 2.76 MPa after five treatment cycles in ISO-standard sand. (2) Field validations in Ahoskie and Sanya demonstrated the efficacy of MICP in coastal erosion control through tailored delivery systems and environmental adaptations. Sanya’s studies highlighted seawater-compatible MICP solutions, achieving maximum 1743 kPa penetration resistance in the atmospheric zone and layered “M-shaped” CaCO₃ precipitation in tidal regions. (3) Experimental studies revealed that MICP treatments (2–4 cycles) reduced maximum scour depth by 84–100% under unidirectional currents (0.3 m/s) with the maximum surface CaCO₃ content reaching 3.8%. (4) Numerical simulations revealed MICP enhanced seabed stability by increasing vertical effective stress and reducing pore pressure. Comparative analysis demonstrates that while the destabilization depth of untreated seabed exhibits a linear correlation with wave height increments, MICP-treated seabed formations maintain exceptional stability through cohesion-enhancing properties, even when subjected to progressively intensified wave forces. This review supports the use of biomineralization as a sustainable alternative for shoreline protection, seabed stabilization, and offshore foundation integrity. Full article

This study presents the first species-level assessment of zooplankton communities within a designated Special Area of Conservation (SAC, ES7020122) in the coastal waters of an oceanic island in the Atlantic Ocean, conducted in a previously under-sampled protected coastal region. Copepods emerged as the predominant taxa, offering key insights into early-stage community structure and potential indicators of ecological dynamics in marine ecosystems. Zooplankton biomass and abundance were primarily driven by organisms in the 200–500 µm size fraction, with spatial variation observed across latitudinal transects. A total of 44 copepods species were identified, including dominant genera (Oncaea, Oithona, and Clausocalanus) characteristic of subtropical Atlantic ecosystems. Several indicator species (e.g., Candacia ethiopica and Oncaea scottodicarloi) showed spatial patterns. While no direct impacts from the recent 2021 volcanic eruption were detected, the dominance of opportunistic copepods and the observed diversity suggest a potential adaptive response and resilience of the pelagic community to periodic geological disturbances. These results provide a valuable ecological baseline for future long-term monitoring under the Marine Strategy Framework Directive and underscore the importance of copepods as indicators of coastal ecosystem structure and variability. Full article

Research on the dynamic mechanisms driving the accumulation of anthropogenic marine debris (AMD) in highly dynamic environments, such as extensive sandy beaches, remains limited. Unmanned aerial vehicles (UAVs) can be used to map macro-marine litter in these environments over large temporal and spatial scales, but several challenges remain in their interpretation. In this study, secondary school students participated in a citizen science initiative, during which they identified, marked, and classified waste items using a series of UAV orthophotos collected along an 800 m extended Italian beach in different seasons. A specific training program and a collection of working tools were developed to support these activities, which were carried out under the constraints imposed by the COVID-19 pandemic. The accuracy of the citizen science approach was evaluated by comparing its results with standard in situ visual census surveys conducted in the same area. This methodology not only enabled an analysis of the temporal dynamics of AMD accumulation but also served an important educational function. The effectiveness of the learning experience was estimated using pre- and post-activity questionnaires. The results indicate a clear improvement in the students’ knowledge, interest, and awareness regarding marine litter, highlighting the potential of citizen science to both support environmental monitoring and promote sustainability education among younger generations. Full article