Search Results (48)

The increasing demand for sustainable disease management in aquaculture has intensified interest in plant-based therapeutics. This study evaluated the formulation and efficacy of andrographolide-loaded nanostructured lipid carriers (AND-NLCs) in Nile tilapia (Oreochromis niloticus) challenged with Streptococcus agalactiae ENC06. AND-NLCs were prepared by the phase-inversion technique and characterized by dynamic light scattering, transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), and in vitro release profiling. Antibacterial activity was assessed by measuring inhibition zone diameters, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC). Growth performance, feed utilization, hepatosomatic index (HSI), and disease resistance were evaluated over a 60-day feeding trial. The AND-NLCs exhibited an optimal particle size (189.6 nm), high encapsulation efficiency (90.58%), sustained release, and structural stability. Compared to the free AND and control group, AND-NLC supplementation significantly improved growth, feed efficiency, HSI, and positive allometric growth. It also enhanced survival (73.3%) and relative percent survival (RPS = 65.6%) following S. agalactiae ENC06 infection. Antibacterial efficacy and physiological responses showed positive correlations with nanoparticle characteristics. These findings suggest that AND-NLCs enhance bioavailability and therapeutic efficacy, supporting their potential as a functional dietary additive to promote growth and improve disease resistance in tilapia aquaculture. Full article

This study investigated mealworm frass as a sustainable substrate for Pleurotus ostreatus cultivation while valorizing mushroom stems as aquaculture feed. Mushrooms were grown on substrates containing 0–15% frass, and nutritional analyses were conducted on both fruiting bodies (for human consumption) and stems (for fish feed). Increasing frass levels significantly enhanced protein content, rising from 7.78% to 22.31% in stems and 24.74% to 30.99% in fruiting bodies. Lipid concentrations showed minor fluctuations while, in contrast, β-glucan content declined with high frass inclusion percentages. Essential amino acid levels peaked at 7.37% in stems (15% frass) and 8.08% in fruiting bodies (12.5% frass). Polyunsaturated fatty acids dominated the fatty acid profile, increasing with high frass levels. Mushroom bodies and stems were additionally investigated for their antimicrobial activity to determine whether they could offer protection against common fish and human pathogens. Antimicrobial assays revealed that dichloromethane extracts from stems grown on 12.5% and 15% frass exhibited inhibitory activity (inhibition zones of 10–11 mm) against Tenacibaculum maritimum, a microorganism that poses a significant threat to aquaculture. These findings highlight mealworm frass as a promising substrate for enhancing mushroom nutritional value while providing a sustainable, protein-rich feed ingredient for aquaculture. 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

Sustainable seaweed cultivation is crucial for marine environmental protection, ecosystem health, socio-economic development, and carbon sequestration. Accurate and timely information on the distribution, extent, species, and production of cultivated seaweeds is essential for tracking biomass production, monitoring ecosystem health, assessing environmental impacts, optimizing cultivation planning, supporting investment decisions, and quantifying carbon sequestration potential. However, this important information is usually lacking. This study developed a high-precision monitoring approach by integrating Otsu thresholding features with random forest classification, implemented through Google Earth Engine using Sentinel-2 imagery (10-m). The method was applied to analyze spatiotemporal variations of seaweed cultivation across the Korean Peninsula from 2017 to 2023. Results showed that annual cultivation acreage in North Korea remained relatively stable between 1506 and 2033 ha, while it experienced a significant increase of 8209 ha in South Korea. By integrating spectral features, seaweed phenology, and field cultivation practices, we successfully differentiated the predominant species: laver (Pyropia) and kelp (Saccharina and Undaria). During the 2022–2023 cultivation season, South Korea’s farms comprised 78% laver and 22% kelp, while North Korea’s showed an inverse distribution. A strong correlation (r² = 0.99) between acreage and seaweed production enabled us to estimate annual seaweed production in North Korea, effectively addressing data gaps in regions with limited statistics. Our approach demonstrates the potential for global seaweed cultivation monitoring, while the spatial analysis lays the foundation for identifying potential cultivation zones. Given the relatively low initial investment requirement of seaweed farming and significant economic return, this approach offers valuable insights for promoting economic development and food security, ultimately supporting sustainable aquaculture management. Full article

The rapid expansion of large-scale aquaculture has created a demand for more efficient and sustainable farming systems. Among these, land-based circular tank aquaculture is emerging as a key solution due to its high efficiency, scalability, and effective waste management capabilities. Optimizing the hydrodynamic characteristics of these tanks is crucial for improving water quality management and ensuring the health of cultured fish. This study investigates the hydrodynamic characteristics of large land-based circular tanks, focusing on the effects of water pusher configurations and the presence of fish on flow dynamics and sewage collection efficiency. Field experiments were conducted under two conditions: with and without fish, while varying the pusher diameter, deployment angles, and the number of pushers. The flow characteristics at different layers of the tanks were measured using Acoustic Doppler Velocimetry. The results indicate that the pusher deployment has a more significant impact on the flow field and hydrodynamic characteristics compared with the pusher diameter. The optimal configuration for water circulation and sewage collection was identified when the pusher diameter was 11 cm, the deployment angle was 45°, and the number of pushers was 6. The presence of fish significantly influenced the flow field distribution by expanding high velocity flow zones. The findings provide a theoretical basis for optimizing water pusher deployment in large-scale circular tanks with fish, thereby contributing to improved water quality management and fish health. Full article

Owing to the abundant land resources in the intertidal zone, the central coastal area of Jiangsu Province, China, has implemented large-scale activities such as tidal flat reclamation, aquaculture, and harbor construction, which have strongly affected the local hydrodynamic environment and the evolution of the mudflat. In this study, based on the 1984–2022 multisource remote sensing image data, an enhanced waterline method (EWM) combined with an average slope method (ASM) were adopted to obtain the spatial–temporal evolution characteristics of the continental coastline and intertidal zone in central Jiangsu Province for six typical years, exhibiting the coastal variations at critical year intervals in response to former large-scale coastal development and subsequent coastal zone protection. Results showed that the coastlines significantly advanced toward the sea. The deposited coast moved toward the seaside at an annual rate of 85.91 m, and the reclaimed coast advanced toward the seaside at a yearly rate of 129.25 m, which were dominated by natural siltation and reclamation activities of mudflats. In the past forty years, the coast’s erosion and siltation transition node has gradually moved southward from the Sheyang Estuary to the Simaoyou Estuary. Affected by reclamation and coastal erosion, the most drastic changes in the slope of the erosive intertidal zone occurred in the section from Binhai Port to the Biandan Estuary, ranging from 2‰ to 14‰. The silted coastal section from the Sheyang Estuary to the Xinyang Estuary increased in average slope from 0.89‰ to 2.43‰ as a result of the continuous intensification of erosion. The area of the intertidal mudflat decreased by 47.76% from 1378.59 to 720.11 km², whereas the mean width of the intertidal zone decreased by 48.02%, from 5518.44 m to 2868.36 m. This study provides current situations of the dynamic changes in the muddy coast of the central Jiangsu coast, which could be a comparison and reference for the sustainable development, utilization, and protection of similar muddy coasts globally. Full article

Irrational land use has triggered many serious ecological problems worldwide, especially in regions where human–land conflicts are prominent. However, the driving mechanisms at different spatiotemporal scales vary and have not been addressed in detail. This study explored the variations of land use and landscape patterns from 1990 to 2020 in the Dongting Lake Ecological Economic Zone (DLEEZ) by land-use transfer matrix, landscape pattern indices methods, etc. We also combined the geographical detector and geographically and temporally weighted regression (GTWR) methods to analyze the spatiotemporal changes in driving forces of land-use changes. The results indicated that forest land, cropland, and wetland were the predominant land-use types, accounting for nearly 90% of the total. Cropland decreased by a total of 1787.55 km² during the 30-year period, and land-use changes mainly involved the conversion of cropland to other land-use types. The overall fragmentation of the regional landscape increased, with the fragmentation of forest land and cropland increasing. Land-use changes were mainly influenced by human activities like socio-economic and policy factors. Notably, the development of agriculture and aquaculture poses a threat to the maintenance of the area of wetland in the DLEEZ. This study provides a reliable scientific basis for mitigating land-use conflicts and rationally planning land use to formulate a sustainable development strategy for land resources in the DLEEZ. Full article

Global fisheries’ production has intensified rapidly over recent decades, making significant contributions to food security and economic development. However, this growth has exerted pressure on marine ecosystems and altered coastal nitrogen cycling. This study focused on Sansha Bay, an important aquaculture harbor in SE China, with measurements of environmental parameters and nitrate N–O isotopic compositions, to explore the impact of distinct mariculture types on nitrogen cycling in a coastal farming bay. The mean nitrate concentration was 120.7 ± 24.2 μmol dm⁻³, with a mean N/P ratio of 69.6 ± 19.6, indicating that the water column is in a state of eutrophication. Different aquaculture practices influence the nutrient status of water, with mixed farming (shellfish, seaweed, and fish) increasing nitrate concentrations and reducing N/P ratios, while seaweed farming reduces nitrate concentrations and increases N/P ratios. In spring, the average δ¹⁵N and δ¹⁸O values of nitrate in the water column were 8.4‰ and 8.7‰, respectively, compared with values of 9.8‰ and 4‰ recorded previously in winter. Such variation may be attributed to the greater influence of seaweed farming in spring when nitrate cycling is driven mainly by assimilation. In terms of aquaculture type, nitrate assimilation was stronger in seaweed farming zones, and nitrification was more pronounced in mixed farming zones. Overall, the results demonstrate that different mariculture types in Sansha Bay influence nitrogen cycling in the water body, with seaweed-based aquaculture systems contributing to the sustainable development of marine aquaculture by effectively mitigating eutrophication. 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

Reservoirs are hotspots for emissions of the greenhouse gas nitrous oxide; however, the nitrite cycling processes associated with nitrous oxide production therein remain poorly understood, limiting a better assessment of the potential for reservoirs to emit nitrous oxide. Accordingly, this study presents the application of the natural abundance isotope technique combined with a geochemical model to elucidate the nitrite cycling in the freshwater aquaculture and non-aquaculture zones of a large artificial reservoir in eastern China. We employed nitrite dual isotopes to identify nitrite transformation processes. Additionally, a steady-state model was used to estimate the rates of these processes as well as the residence time of nitrite. Our findings indicate that nitrite production in this reservoir may be primarily driven by ammonia oxidation. However, the pathways of nitrite removal differ notably between the aquaculture and non-aquaculture zones, suggesting a significant impact of the aquaculture activities. The steady-state model calculations revealed that nitrification may be more pronounced in the aquaculture zones compared to the non-aquaculture zones, which may be related to the altered balance of competition for substrates between phytoplankton and microbes induced by aquaculture activities. Moreover, we observed a latitude-dependent increase in the significance of nitrite oxidation in natural environments, highlighting potential implications for regional and global nitrogen cycling. Our study highlights the complexity of the nitrite cycle and emphasizes the roles of both natural and anthropogenic factors in shaping nitrogen dynamics within freshwater reservoirs. This understanding contributes to a more accurate assessment of the greenhouse gas emission potential of reservoirs, offering valuable implications for the adoption of sustainable aquaculture practices to mitigate climate impacts and support global sustainable development goals. Full article

Achieving precise and swift monitoring of aquaculture ponds in coastal regions is essential for the scientific planning of spatial layouts in aquaculture zones and the advancement of ecological sustainability in coastal areas. However, because the distribution of many land types in coastal areas and the complex spectral features of remote sensing images are prone to the phenomenon of ‘same spectrum heterogeneous objects’, the current deep learning model is susceptible to background noise interference in the face of complex backgrounds, resulting in poor model generalization ability. Moreover, with the image features of aquaculture ponds of different scales, the model has limited multi-scale feature extraction ability, making it difficult to extract effective edge features. To address these issues, this work suggests a novel semantic segmentation model for aquaculture ponds called MPG-Net, which is based on an enhanced version of the U-Net model and primarily comprises two structures: MS and PGC. The MS structure integrates the Inception module and the Dilated residual module in order to enhance the model’s ability to extract the features of aquaculture ponds and effectively solve the problem of gradient disappearance in the training of the model; the PGC structure integrates the Global Context module and the Polarized Self-Attention in order to enhance the model’s ability to understand the contextual semantic information and reduce the interference of redundant information. Using Sentinel-2 and Planet images as data sources, the effectiveness of the refined method is confirmed through ablation experiments conducted on the two structures. The experimental comparison using the FCN8S, SegNet, U-Net, and DeepLabV3 classical semantic segmentation models shows that the MPG-Net model outperforms the other four models in all four precision evaluation indicators; the average values of precision, recall, IoU, and F1-Score of the two image datasets with different resolutions are 94.95%, 92.95%, 88.57%, and 93.94%, respectively. These values prove that the MPG-Net model has better robustness and generalization ability, which can reduce the interference of irrelevant information, effectively improve the extraction precision of individual aquaculture ponds, and significantly reduce the edge adhesion of aquaculture ponds in the extraction results, thereby offering new technical support for the automatic extraction of aquaculture ponds in coastal areas. Full article

Due to the increasing impact of climate change and human activities on marine ecosystems, there is an urgent need to study marine water quality. The use of remote sensing for water quality inversion offers a precise, timely, and comprehensive way to evaluate the present state and future trajectories of water quality. In this paper, a remote sensing inversion model utilizing machine learning was developed to evaluate water quality variations in the Ma’an Archipelago Marine Special Protected Area (MMSPA) over a long-time series of Landsat images. The concentrations of chlorophyll-a (Chl-a), phosphate, and dissolved inorganic nitrogen (DIN) in the sea area from 2002 to 2022 were inverted and analyzed. The spatial and temporal characteristics of these variations were investigated. The results indicated that the random forest model could reliably predict Chl-a, phosphate, and DIN concentrations in the MMSPA. Specifically, the inversion results for Chl-a showed the coefficient of determination (R²) of 0.741, the root mean square error (RMSE) of 3.376 μg/L, and the mean absolute percentage error (MAPE) of 16.219%. Regarding spatial distribution, the concentrations of these parameters were notably elevated in the nearshore zones, especially in the northwest, contrasted with lower concentrations in the offshore and southeast areas. Predominantly, the nearshore regions with higher concentrations were in proximity to the aquaculture zones. Additionally, nutrients originating from land sources, transported via rivers such as the Yangtze River, as well as influenced by human activities, have shaped this nutrient distribution. Over the long term, the water quality in the MMSPA has shown considerable interannual fluctuations during the past two decades. As a sanctuary, preserving superior water quality and a healthy ecosystem is very important. Efforts in protection, restoration, and management will demand considerable labor. Remote sensing has demonstrated its worth as a proficient technology for real-time monitoring, capable of supporting the sustainable exploitation of marine resources and the safeguarding of the marine ecological environment. Full article

The aquaculture industry requires green solutions to solve several environmental challenges, including adequate wastewater remediation and natural drug applications to treat bacteria- and virus-related diseases. This study investigated the feasibility of cultivating the dinoflagellate Durusdinium glynnii in aquaculture wastewater from shrimp rearing in a synbiotic system (AWW-SS), with different dilutions of f/2 medium (FM). Interestingly, D. glynnii demonstrated enhanced growth in all AWW–SS treatments compared to the control (FM). The highest growth rates were achieved at AWW-SS:FM dilutions of 75:25 and 50:50. The removal of total nitrogen and total phosphorus reached 50.1 and 71.7%, respectively, of the crude AWW–SS. Biomass extracts of D. glynnii grown with AWW–SS were able to inhibit the growth of the bacteria Vibrio parahaemolyticus (inhibition zone of 10.0 ± 1.7 mm) and V. vulnificus (inhibition zone of 11.7 ± 1.5 mm). The presented results demonstrate that the dinoflagellate D. glynnii is a potential candidate for the development of circularity for sustainable aquaculture production, particularly by producing anti–Vibrio compounds at a near-zero cost. Full article

Under the double pressures of economic growth and ecological environment protection, sea green transformation and the sustainable development of mariculture are critical. This paper constructs an evolutionary game model with the government as the main body and mariculture farmers (enterprises) as the main body and puts forward the research hypothesis. Based on 2006–2019 longitudinal data of nine provinces along China’s coast, using multi-period Difference-in-Difference (DID) and dual robust estimation, we empirically investigate the national oceanic ranch demonstration zones for the influence of the green sea aquaculture and their mechanism of action. The results showed that (1) the efficiency of green level of mariculture industry in China is not high, and the establishment of national marine pasture demonstration zone has not effectively promoted the improvement of green level of mariculture industry; (2) the institutional environment, unreasonable industrial structure, and lack of scientific and technological innovation have an effect on the national oceanic ranch demonstration area as the main causes of failure to effectively promote marine green farming; (3) the establishment of the national multi-period demonstration area in the north significantly hindered the growth of the green level of mariculture and fell into the “policy trap”, while the establishment of the national multi-period demonstration area in the south significantly promoted the growth of the green level of mariculture. The conclusions of this paper provide an empirical basis and reference for the improvement of the national marine pasture demonstration zone policy and the green transformation of mariculture to a certain extent. Full article

Biofloc technology (BFT) offers an innovative eco-friendly approach that is particularly applicable in shrimp farming. Penaeus vannamei is the most important seafood species in terms of global economic value. Nevertheless, its increasing global demand highlights the necessity for sustainable production of P. vannamei shrimps outside their native range, assuring the avoidance of genetic pollution risk. Towards this direction, the present study focuses on the feasibility of tropical shrimp species aquaculture in indoor systems evaluating BFT application in temperate zones. The achievability of P. vannamei cultivation inside greenhouses in temperate latitudes is thoroughly examined and a representative experimental biofloc setup for P. vannamei within a greenhouse in Northern Greece is demonstrated. Nevertheless, there are two major limitations, related to economy and ecology, namely the energy demand for high seawater temperature and the fact that most reared shrimps are non-indigenous species setting risk for genetic pollution, respectively. To overcome the former, energy-saving measures such as tank and greenhouse insulation in combination with a microclimate chamber construction were implemented to optimize water temperature at minimal cost. Concerning the latter, there is clear evidence that P. vannamei populations cannot be established in the Mediterranean, setting aside any environmental risk. Overall, based on the developed and tested pilot prototype, employment of optimal management practices, innovative manufacturing and clean energy alternatives, and the utilization of ecosystem services could reduce the environmental impact and maximize the profitability of biofloc operations. These actions could probably permit sustainable and economically viable farming of P. vannamei employing BFT within greenhouses in the Mediterranean. Full article