Search Results (142)

Excessive reliance on traditional energy sources such as coal, petroleum, and gas leads to a decrease in natural resources and contributes to global warming. Consequently, the adoption of renewable energy sources in power systems is experiencing swift expansion worldwide, especially in offshore areas. Floating solar photovoltaic (FPV) technology is gaining recognition as an innovative renewable energy option, presenting benefits like minimized land requirements, improved cooling effects, and possible collaborations with hydropower. This study aims to assess the levelized cost of electricity (LCOE) associated with floating solar initiatives in offshore and onshore environments. Furthermore, the LCOE is assessed for initiatives that utilize floating solar PV modules within aquaculture farms, as well as for the integration of various renewable energy sources, including wind, wave, and hydropower. The LCOE for FPV technology exhibits considerable variation, ranging from 28.47 EUR/MWh to 1737 EUR/MWh, depending on the technologies utilized within the farm as well as its geographical setting. The implementation of FPV technology in aquaculture farms revealed a notable increase in the LCOE, ranging from 138.74 EUR/MWh to 2306 EUR/MWh. Implementation involving additional renewable energy sources results in a reduction in the LCOE, ranging from 3.6 EUR/MWh to 315.33 EUR/MWh. The integration of floating photovoltaic (FPV) systems into green hydrogen production represents an emerging direction that is relatively little explored but has high potential in reducing costs. The conversion of this energy into hydrogen involves high final costs, with the LCOH ranging from 1.06 EUR/kg to over 26.79 EUR/kg depending on the complexity of the system. Full article

Offshore wind turbines are subjected to long-term wave loads, which shorten their service life. Marine aquaculture cages are common structures in the ocean engineering field. Therefore, investigating the hydrodynamic characteristics of combined wind turbine and cage facilities under wave loads is crucial. This study employs a porous medium model to analyze the hydrodynamic behavior of a fixed wind turbine base integrated with cages under finite-depth wave conditions. First, the transmission coefficients of waves passing through cages at different positions were examined under varying cage solidity conditions. The results indicate that the cages minimally affect wave height in regions close to the cage group. Subsequently, the wave forces acting on the fixed wind turbine base behind the cages were analyzed under different solidity and wave height conditions. The variation curves of the drag coefficient and inertia coefficient were obtained for solidity values ranging from 0.3 to 0.6 and Keulegan–Carpenter (KC) numbers between 1 and 4. Full article

This paper encapsulates the advancements in marine renewables utilization technologies globally, analyzed through the lenses of research emphasis and variations in device mechanisms. The multi-energy complementarity and the integration of marine renewable energy systems with aquaculture technologies are discussed, and the engineering applications are introduced. Tidal energy and offshore wind energy technologies have achieved mature commercial operation, while tidal current energy and wave energy technologies are undergoing full-scale prototype testing. Temperature-difference energy technology has reached the full-scale prototype testing phase, whereas salinity-gradient energy technology remains in the laboratory verification stage. In recent years, many researchers have conducted engineering measurements, and further breakthroughs are needed in critical enabling technologies and safety measures. From the standpoint of geographical integration, the realization of aquaculture with offshore wind energy and wave energy or tidal current energy is simpler. The integration of aquaculture with marine renewable energy technologies represents a promising avenue for the future development and global utilization of marine energy resources. Full article

The use of remote sensing images to analyze the change characteristics of large-scale aquaculture areas and monitor aquaculture violations is of great significance for exploring the law of marine aquaculture and assisting the monitoring and standardization of aquaculture areas. In this study, a violation monitoring framework for marine aquaculture areas based on image recognition using an enhanced Mask R-CNN architecture incorporating a convolutional block attention module (CBAM) and soft non-maximum suppression (Soft-NMS) is proposed and applied in Sandu’ao. The results show that the modified Mask R-CNN, when compared to the most basic Mask R-CNN model, exhibits higher accuracy in identifying marine aquaculture areas. The aquaculture patterns in the Xiapu region are characterized by two peak periods of aquaculture area fluctuations, occurring in March and October. Conversely, July marks the month with the smallest aquaculture area in the region and is influenced by factors such as water temperature and aquaculture cycle. Significant changes in the aquaculture area were observed in January, March, June, August, and October, necessitating rigorous monitoring. Furthermore, monitoring and analysis of aquaculture areas have revealed that despite the reduction in illegal aquaculture acreage since 2017 due to the implementation of functional zone planning for marine aquaculture areas, illegal aquaculture activities remain prevalent in prohibited and restricted zones in Xiapu, accounting for a considerable proportion. Full article

This study investigates the impact of rising sea surface temperature (SST), increasing carbon dioxide (CO₂) emissions, and precipitation variability (PREC) on Korea’s coastal and offshore fisheries production (COFP) from 1993 to 2023 using an autoregressive distributed lag (ARDL) model. The results confirm a long-run cointegration relationship, where a 1% increase in SST, CO₂, and PREC is associated with respective declines of 3.52%, 0.82%, and 0.34% in COFP, respectively, suggesting persistent negative effects of ocean warming, acidification, and hydrological variability on fisheries production. Robustness checks using Fully Modified Ordinary Least Squares (FMOLS) and Canonical Cointegrating Regression (CCR) validate the stability of the ARDL results. The short-run analysis reveals that past production levels significantly influence current COFP, while SST fluctuations exhibit delayed but economically meaningful effects. The error correction term (−0.75, p < 0.01) confirms a rapid adjustment toward equilibrium following short-term deviations. These findings underscore the necessity of climate-resilient fisheries management. Policy recommendations include adaptive harvest regulations, climate-integrated stock assessments, and enhanced international cooperation for transboundary fish stocks. Additionally, expanding Marine Protected Areas, promoting climate-resilient aquaculture, and strengthening stock enhancement programs through selective breeding and seed release of climate-adapted species are essential for sustaining fisheries under climate change. Full article

The integrated development of offshore wind power and marine aquaculture represents a promising approach to the sustainable utilization of ocean resources. The present study investigated the hydrodynamic response of an innovative combination of a wind farm monopile and pontoon raft aquaculture facilities (PRAFs). Physical water tank experiments were conducted on PRAFs deployed around a wind farm monopile using the following configurations: single- and three-row arrangements of PRAFs with and without a monopile. The interaction between the aquaculture structure and the wind farm monopile was examined, with a particular focus on the mooring line tensions and bridle line tensions under different wave conditions. Utilizing the wind farm monopile foundation as an anchor, the mooring line tension was reduced significantly by 16–66% in the single-row PRAF. The multi-row PRAF arrangement experienced lower mooring line tension in comparison with the single-row PRAF arrangement, with the highest reduction of 73%. However, for the bridle line tension, the upstream component was enhanced, while the downstream one was weakened with a monopile, and they both decreased in the multi-row arrangement. Finally, we developed numerical models based on flume tank tests that examined the interactions between the monopile and PRAFs, including configurations of a single monopile, along with single- and three-row arrangements of PRAFs. The numerical simulation results confirmed that the monopile had a dampening effect on the wave propagation of 5% to 20%, and the impact of the pontoons on the monopile was negligible, implying that the integration of aquaculture facilities around wind farm infrastructure may not significantly alter the hydrodynamic loads experienced by the monopile. Full article

Offshore mariculture is a critical component of China’s aquaculture sector, but its rapid expansion presents significant challenges to sustainable marine resource management. This study utilizes high-resolution remote sensing data (2017–2023) and advanced ConvNeXt V2 algorithms to quantitatively analyze the spatiotemporal dynamics of offshore mariculture and explore its spatial distribution in relation to marine functional zoning policies. Through a detailed classification of six mariculture types, this study reveals significant spatial shifts, with China’s offshore mariculture transitioning from a model characterized by a “coastal, concentrated layout” to a new paradigm of “deep-sea and far-sea expansion, multi-point distribution”. Notably, the area of deep-sea and far-sea mariculture increased by 41.8% in regions with water depths of 50 m or more from 2018 to 2022. However, in 2022, the actual mariculture area accounted for only 0.608% of the designated functional zones, while 61.79% of mariculture activities occurred outside these planned zones, indicating a considerable spatial mismatch between mariculture practices and zoning plans. This study underscores the urgent need to optimize spatial planning and regulatory frameworks to balance economic growth with environmental sustainability, offering novel insights and actionable recommendations for the coordinated development of China’s marine economy. Full article

Background: As an innovative approach to deep-sea aquaculture, fish farm vessels offer a dual benefit by alleviating the pressure on offshore fishing resources while providing an additional high-quality protein source. However, the potential impacts of vessel coatings on farmed fish remain poorly understood. Methods: In this study, to investigate the effects of vessel coatings on the large yellow croaker (Larimichthys crocea), we established four experimental groups with coating concentrations at 1-fold, 10-fold, 20-fold, and 80-fold levels. Antioxidant enzyme activities in kidney tissues were measured across all groups, while histological and transcriptome analyses were specifically conducted for the 1-fold and 80-fold concentration groups. Results: Firstly, significant alterations in antioxidant enzyme activity were observed in the 80-fold concentration group. Moreover, histological analysis demonstrated more severe pathological changes in kidney tissue at the higher concentration, including interstitial hemorrhage and tubular epithelial cell fatty degeneration. In addition, we identified 11,902 differentially expressed genes (DEGs) by high-throughput sequencing. KEGG pathway enrichment analysis revealed that the DEGs were predominantly involved in critical biological processes, including endoplasmic reticulum protein processing, oxidative phosphorylation, cytokine–cytokine receptor interactions, cell cycle regulation, DNA replication, and PPAR signaling pathways. Finally, the validation of nine selected DEGs through quantitative real-time PCR (qRT-PCR) showed significant correlation with RNA-Seq data, confirming the reliability of our transcriptome analysis. Conclusions: This study provides preliminary insights into the antioxidant stress response mechanisms of L. crocea to coating exposure and establishes a theoretical foundation for optimizing healthy fish farming practices in aquaculture vessels. Full article

Given their small size and low value in commercial fishing and aquaculture, little is known about the seasonal spatial distribution patterns and characteristics of the bobtail squid Euprymna berryi and Euprymna morsei in seas around China. Thus, we conducted seasonal bottom-trawling surveys in the southern Yellow and East China Seas during 2018 and 2019. Our results showed that E. berryi migrated from inshore areas (Yushan fishing grounds) during the summer and autumn to offshore areas (Wentai fishing grounds) during the winter. In contrast, E. morsei migrated from shallower water areas during the spring to deeper water areas during the winter. The highest abundance of E. berryi versus E. morsei was found in areas where temperatures were 25.29–28.02 °C compared with 19.54 °C (33.43–34.04‰ versus 34.43‰), respectively, during the summer; 20.99–21.69 °C compared with 21.98–22.70 °C (34.07–34.50‰ versus 33.80–33.60‰), respectively, during autumn; and 17.13–20.36 °C compared with 10.51–13.49 °C (34.23–34.46‰ versus 31.69–33.42‰), respectively, during winter. We predict that suitable habitats for E. berryi would expand more northward under SSP585-2050, whereas those for E. morsei would shrink into more northern locations under SSP370-2100 and SSP585-2100. The SSP245-2100 and SSP585-2100 scenarios had the most negative impacts on the distributions of both species. Such insights improve our understanding of the population dynamics and habitat requirements of both species to support their population management and exploitation in response to future climate change. Full article

With the planning and construction of marine ranching in China, water quality has become one of the critical limiting factors for the development of marine ranching. Due to geographical differences, marine ranches exhibit varying water quality conditions under the influence of the continental shelf. To the best of our knowledge, there is limited research on satellite-based water quality monitoring for marine ranching and the spatiotemporal variations in marine ranches in different geographical locations. Chlorophyll-a (Chl-a) is a key indicator of the ecological health and disaster prevention capacity of marine ranching, as it reflects the conditions of eutrophication and is crucial for the high-quality, sustainable operation of marine ranching. Using a physically based model, this study focuses on the retrieval of Chl-a concentration in Daya Bay. The coefficient of determination (R²) between the model retrieval values and the in situ Chl-a data is 0.69, with a root mean square error (RMSE) of 1.52 μg/L and a mean absolute percentage error (MAPE) of 44.25%. Seasonal variations in Chl-a concentration are observed in Daya Bay and are higher in spring–summer and lower in autumn–winter. In the YangMeikeng waters, Chl-a concentration shows a declining trend with the development of marine ranching. A comparison between the YangMeikeng (nearshore) and XiaoXingshan (offshore) marine ranches suggests that offshore ranching may be less impacted by terrestrial pollutants. The primary sources of Chl-a input in Daya Bay are the Dan’ao River and the aquaculture areas in the northeastern part of the bay. This study can provide valuable information for the protection and management of marine ranching. Full article

This study evaluated the effects of different lipid sources—fish oil (FO), soybean oil, rapeseed oil, and palm oil—on the growth and muscle quality of golden pompano (Trachinotus ovatus) cultured in offshore cages for 10 weeks. Three diets (D1–D3) were formulated: D1 used only fish oil, D2 blended fish, rapeseed oil, and palm oil, and D3 combined fish and soybean oils. Fish in the D1 group showed the highest weight gain, specific growth rate, and muscle protein content, significantly outperforming D3. No significant differences in muscle lipid content or edible quality were found between groups. D1 had the highest levels of long-chain and n-3 polyunsaturated fatty acids (PUFA), while D3 had higher n-6 PUFA. Saturated and monounsaturated fatty acids were higher in D1 and D2 than in D3. Muscle volatiles like aldehydes and amines were elevated in D1, with more pleasant flavors compared to D2 and D3. Muscle texture was superior in D2. These results suggest that rapeseed and palm oils can enhance growth, flavor, and texture in fish on low FO diets, offering a sustainable alternative to reduce reliance on marine-based feed in aquaculture. Full article

This research evaluates the potential spaces of deep offshore waters for cultivating the Larimichthys crocea, analyzing ocean profile temperature data from 2000 to 2022 according to the species’ environmental temperature suitability. There are significant seasonal variations and differences in habitat distributions of different temperature ranges in China’s surrounding waters. The range of maximum living space obtained according to the tolerance temperature shows a trend of being larger in summer and smaller in winter; and the range of viable habitat space obtained based on the suitable and optimal temperature shows a trend of being smaller in summer and larger in winter. Broad areas meeting tolerance temperatures offer broad, yet impractical, site selection options. In contrast, areas with optimal temperatures are limited, which means the availability of ideal site locations is very restricted. Regions consistently within the 20–28 °C range are best for practical site selection. Year-round suitable areas are primarily found at depths of 30 to 90 m in the southern East China Sea and the South China Sea, particularly within the 40 to 50 m depth range. Water mass like the South China Sea Surface Water and the Kuroshio Surface Water consistently maintain suitable temperatures, making them ideal for aquaculture. Full article

To enhance the stability and safety of marine aquaculture facilities by addressing the limited uplift resistance capacity and susceptibility to deflection of conventional straight-shafted piles, this study introduces an improved H-pile anchor and conducted laboratory experiments. The new anchor incorporates resized H-piles with wing plates added to both sides, optimized for area and placement, as well as an adjusted loading angle. The findings demonstrate a positive correlation between the uplift resistance capacity of the H-pile anchor and its length and width, indicating that while increased pile length significantly enhances resistance, widening has a minimal impact. Additionally, enlarging the wing plate area improves the resistance; however, efficiency (δ) decreases with the increase in the area, suggesting the existence of an optimal size. The optimal wing plate dimensions (L = 80 mm, W = 25 mm) improve uplift resistance by at least 10.6% compared to non-wing pile anchors. Furthermore, positioning the wing plates at the base of the pile anchor rather than the top enhances resistance by approximately 13.8%. Setting the anchor layout angle to 45° reduced the displacement under inclined loads. This research provides essential theoretical support and practical guidance for strengthening the safety and stability of marine aquaculture facilities. Full article

Phytoplankton is essential in coastal marine ecosystems, aiding ecosystem stability and development of marine economy. Coastal ecosystems, as a transitional zone, feature complex, variable environmental factors that significantly affect phytoplankton growth. To assess the factors influencing the growth of phytoplankton in the bay area, this study measured chlorophyll a (Chla), nutrients, and four antibiotics (sulfamethoxazole, sulfadiazine, ciprofloxacin, and enrofloxacin) in seawater, as well as total nitrogen and total phosphorus contents in sediments at 25 stations in Lianzhou Bay. Principal component analysis and the risk quotient (RQ) were utilized for analysis and assessment. The results indicate that the factors influencing Chla concentrations are inconsistent between the nearshore and offshore areas of Lianzhou Bay. Specifically, abundant nutrients, high ammonia levels, and low enrofloxacin concentrations are the primary factors contributing to high Chla concentrations in the nearshore area. In contrast, hydrodynamic conditions, feeding by cultured shellfish, and adequate lighting collectively shape the distribution characteristics of Chla in the offshore area. Additionally, the ecological risk posed by antibiotics in this bay is relatively low. The findings of this study provide scientific evidence for local management of marine pollution sources and the optimization of aquaculture models, which is of great significance for sustainable utilization of marine ecological resources. Full article

The mechanical and hydrodynamic characteristics of single-piece nets are key to the design and optimization of offshore aquaculture net cages. A numerical approach for offshore submerged aquaculture net materials based on the Morison equations and finite element is proposed, simulating the hydrodynamic characteristics of single-piece nets under varying parameters such as wire diameter, mesh size, and flow velocity, and simulating the impact of marine organism attachment on nets by modifying the drag coefficient. The simulation results of nets made from materials such as Copper–Zinc Alloy (Cu-Zn), Zinc–Aluminum Alloy (Zn-Al), Semi-Rigid Polyethylene Terephthalate (PET), and Ultra-High Molecular Weight Polyethylene (UHMWPE) are compared, which provides a theoretical basis for optimizing design parameters and selecting materials for nets based on force conditions and hydrodynamic characteristics. The simulation results indicate that the current force on the net is positively correlated with flow velocity; the maximum displacement of the net is also positively correlated with the flow rate. Compared to other materials, the Cu-Zn net is subjected to the greatest water flow force, while the UHMWPE net experiences the greatest displacement; the larger the diameter of the netting twine, the greater the current force on the net; the mesh size is inversely related to the current force on the net. With increasing drag coefficient, both the maximum displacement of the net and the current force experiences increase, and UHMWPE material nets are more sensitive to increases in the drag coefficient, which indicates a greater impact from the attachment of marine organisms. The density and elastic modulus of the netting material affect the rate of increase in force on the net. The research results can provide a basis for further research on material selection and design of deep-sea aquaculture nets. Full article