Search Results (1,649)

This study investigated the spatial and seasonal dynamics of phytoplankton communities in Jaran Bay, inner Hansan Bay, and outer Hansan Bay, with particular emphasis on size structure and pigment-based indicators of productivity and physiological status. Water sampling was conducted during May, August, and October in 2020, 2022, and 2023 and phytoplankton communities were analyzed using size-fractionated chlorophyll a measurements and high-performance liquid chromatography (HPLC) pigment analysis. Chlorophyll a concentrations exhibited pronounced seasonality, with consistently elevated values in August across all bays. Diatoms were predominant throughout the study period; however, their relative contribution declined in outer Hansan Bay during summer, coinciding with increased contributions from cryptophytes and cyanobacteria. Size-fractionated analyses revealed that large-sized phytoplankton (>20 µm) predominantly consisted of diatoms, whereas small-sized phytoplankton (<20 µm) were composed of diatoms and cryptophytes. Comparisons between fluorometric and pigment-based approaches indicated that pigment-based diagnostics overestimated microphytoplankton contributions, attributable to the presence of small-sized diatoms. Pigment indices further revealed that large-sized phytoplankton were characterized by higher photosynthetic carotenoid concentrations and lower photoprotective carotenoid ratios, indicative of enhanced photosynthetic activity and productivity. Overall, these findings highlight the critical role of phytoplankton size structure in regulating productivity and physiological responses in aquaculture-dominated coastal bays. Full article

With the industry development of sea cucumber Apostichopus japonicus aquaculture, the indoor high cost and low survival rate have become serious problems. Therefore, it is necessary to optimize substrate selection for seedling protection in outdoor pond net cages. This study explores the succession of periphyton on the different substrate surface types, including a curvimurate net (CU), nylon mesh (NM), and ground cages (including a ground cage net (CN) and ground cage plate (CP)), and their effects on the seedling protection of sea cucumbers. In addition, we monitored the substrates’ dry weight, chlorophyll-a, and the community composition of substrates, alongside seedling growth, yield, and survival rate. The results show that a total of 7 phyla, 23 genera, and 31 species were detected on the substrates, with diatoms dominating (19 species) and Chlorophyta (4 species) being the main species. The CU had the highest total number of alga species attached, significantly higher than the other substrates in week 13 (p < 0.05). In week 9, the diatom density dropped to its lowest point, and, after September, it rose with the decrease in water temperature. In terms of dry weight with and without ash, CP increased rapidly in the early stage, with NM, CU, and CP being significantly higher than CN in week 13 (p < 0.05). The chlorophyll-a content showed a decreasing–increasing–decreasing trend, with CU reaching 3.62 ± 0.48 μg/cm² in the 13th week, significantly higher than other substrates (p < 0.05). Finally, the A. japonicus survival rate and yield in the CU group at week 12 were significantly higher than those in the NM and ground cage groups (p < 0.05). At week 17, the average weight, yield, and survival rate in the CU group were still optimal, with the yield 5.76 times that in the initial dosage. These results suggest that the CU has a suitable mesh size, has good permeability, and may stably support sediment, which is conducive to the growth of benthic diatoms. In addition, it can provide sufficient natural feed and a good habitat environment and is the preferred substrate for A. japonicus seedling protection in outdoor pond net cages. Full article

This study evaluated the effects of water renewal rate and temperature on the growth performance and physiological responses of juvenile Piaractus brachypomus reared in a recirculating aquaculture system (RAS). A total of 336 fish (1.35 ± 0.24 g) were distributed in six RAS units under two water renewal rates (42 and 128 L h⁻¹) and three temperatures (26, 29, and 32 °C) for 45 days. Temperature was the main factor affecting growth, with higher final weight and total length at 29 and 32 °C throughout the experimental period. Water renewal rate significantly influenced feeding efficiency and energy allocation. Higher renewal (128 L h⁻¹) increased dissolved oxygen and daily feed intake and resulted in higher hemoglobin levels and hepatic lipid deposition, particularly at 32 °C, indicating greater metabolic activity. Conversely, the lower renewal rate (42 L h⁻¹) was associated with better feed conversion ratios at 29 °C and higher muscle lipid content at 26 °C, suggesting reduced energy expenditure. Hematocrit, total plasma protein, and cholesterol were primarily influenced by temperature, with higher values at 29 and 32 °C, while glucose, triglycerides, and liver enzymes were unaffected. Overall, temperatures of 29–32 °C optimized growth, while water renewal rate modulated feed utilization, physiological responses, and lipid deposition. These findings highlight the importance of jointly optimizing temperature and water renewal rate in RAS to enhance growth performance and metabolic balance in juvenile P. brachypomus. Full article

Coastal pond-to-mangrove restoration has become a prominent Nature-based Solution, yet its short-term ecological effects on waterbird communities remain unclear. We assessed taxonomic, functional, and compositional responses of waterbirds to large-scale restoration in Bamen Bay, Hainan Island, using BACI-style comparisons between restored and unrestored aquaculture ponds in 2021 and 2023. Restored areas exhibited higher taxonomic α diversity and functional richness (p < 0.001), coinciding with rapid habitat diversification following hydrological reconnection. Species richness (p < 0.001), Shannon diversity (p < 0.01), and functional richness (p < 0.01) were consistently higher in restored areas than in aquaculture ponds. In contrast, β diversity patterns diverged between habitats: restored areas remained relatively stable, whereas aquaculture ponds showed greater between-year compositional change (p < 0.05). Guild-specific responses revealed contrasting patterns: herons showed higher diversity in restored habitats (p < 0.05), whereas shorebirds exhibited no significant changes (p > 0.05), consistent with their dependence on open mudflats that were only partially retained. Although no significant declines were detected, functional richness tended to be lower in 2023 (p > 0.05), and ongoing mudflat loss suggests potential long-term risks for mudflat specialists, warranting extended monitoring. Taken together, our findings suggest that effective pond-to-mangrove restoration in Bamen Bay should balance mangrove expansion with the retention of tidal flats and managed shallow-water habitats to support diverse waterbird assemblages. Full article

Penaeus monodon is widely cultured in Asia; however, intensive farming practices often result in water-quality deterioration and compromised production performance. Copper-loaded montmorillonite (Cu-MMT) is a functional additive with adsorption and antimicrobial properties, yet the relative effectiveness of different application strategies remains insufficiently evaluated. In this study, 270 shrimp were assigned to three treatments: a control group (KZ), water application of Cu-MMT (PZ), and dietary inclusion of Cu-MMT (BZ). Juvenile Penaeus monodon with an initial body weight of 3.25 ± 0.15 g were used in the trial. Growth performance, intestinal histology, and rearing-water quality were assessed over a 56-day culture period. Shrimp in the BZ group exhibited a significantly higher weight gain rate (311.88 ± 38.17%) and survival rate (88.04%) than those in the KZ (247.45 ± 32.82%; 76.67%) and PZ (286.49 ± 29.78%; 83.33%) groups (p < 0.05). Intestinal histological observations revealed treatment-associated differences in morphology, with more pronounced intestinal enlargement observed in the PZ group, whereas the BZ group exhibited a more moderate intestinal architecture. Water-quality analyses showed that dietary Cu-MMT supplementation was associated with higher dissolved oxygen levels and lower concentrations of total ammonia nitrogen, sulfide, and dissolved iron, particularly during the later stages of the experiment. Overall, these results indicate that dietary inclusion of Cu-MMT provides more favorable outcomes than water application in improving growth performance and rearing-water quality in P. monodon culture under the experimental conditions tested. These findings highlight the importance of application strategy when evaluating functional additives in shrimp aquaculture. Full article

Betanodavirus infection poses a significant threat to marine fish species in the Mediterranean, affecting both aquaculture and wild populations. Despite increasing evidence of viral circulation in farmed and wild fish, data on natural outbreaks in wild groupers remain limited. This study investigated mortality episodes in wild dusky groupers (Epinephelus marginatus) within two marine protected areas (MPAs): Portofino MPA (Liguria, Italy) and Larvotto MPA (Principality of Monaco) during 2018–2019. Pathological examinations and virological diagnostics confirmed that the causative agents were betanodavirus strains belonging to the RGNNV genotype. Phylogenetic analyses revealed high genetic similarity among viral strains detected at geographically distant sites and across host species, suggesting potential regional connectivity mediated by mobile vectors or environmental transport. Seawater temperature analysis indicated that extreme and prolonged high-water temperatures were prodromal and coincided with observed outbreaks, supporting a role for thermal stress in triggering outbreak onsets. These findings highlight the susceptibility of wild dusky grouper populations to betanodavirus and underscore the interplay between host behavior, environmental conditions, and pathogen dynamics. The study emphasizes the importance of integrated health surveillance strategies within and around MPAs to monitor fish health and environmental parameters, thereby conserving wild fish populations and biodiversity. Full article

Growing pressure on water resources and mineral fertilizer use calls for innovative and resource-efficient agri-food systems. Aquaponics, integrating aquaculture and hydroponics, represents a promising approach for sustainable greenhouse production. This study, aiming to explore alternative water and nutrient sources for greenhouse tomato production without compromising plant adaptability or yield, evaluated the co-cultivation of grape tomato and rainbow trout in a vertical decoupled aquaponic system under controlled greenhouse conditions. Two aquaponic nutrient strategies were tested: unmodified aquaponic water (AP) and complemented aquaponic water (CAP), with conventional hydroponics (HP) as a control, in a Deep Water Culture hydroponic system. Plant performance was assessed through marketable yield and physiological parameters, while system performance was evaluated using combined-biomass Energy Use Efficiency (EUE), Freshwater Use Efficiency (fWUE) and Nitrogen Use Efficiency (NUE), accounting for both plant and fish production. CAP significantly improved tomato yield (9.86 kg m⁻²) compared to AP (2.40 kg m⁻²), although it remained lower than HP (12.14 kg m⁻²). Fresh WUE was comparable between CAP and HP (9.22 vs. 9.24 g L⁻¹), demonstrating effective water reuse. In contrast, EUE and NUE were lower in CAP, reflecting the additional energy demand of the recirculating aquaculture system and nutrient limitations of fish wastewater. These results highlight aquaponics as a water-efficient production system while emphasizing that optimized nutrient management and energy strategies are critical for improving its overall sustainability and performance. Full article

This study examines the hydrological response of the Klambu Dam Catchment in Central Java, Indonesia, to climatic and land cover changes from 2000–2023, with simulations extending to 2040. Utilizing CHIRPS satellite data calibrated with six ground stations, monthly precipitation and temperature datasets were analyzed and projected via linear regression aligned with IPCC scenarios, revealing a marginal temperature decline of 0.21 °C (from 28.25 °C in 2005 to 28.04 °C in 2023) and a 17% increase in rainfall variability. Land cover assessments from Landsat imagery highlighted drastic changes: a 73.8% reduction in forest area and a 467.8% increase in mixed farming areas, alongside moderate fluctuations in paddy fields and settlements. The Thornthwaite-Mather water balance method simulated monthly discharge, validated against observed data with Pearson correlations ranging from 0.5729 (2020) to 0.9439 (2015). Future projections using Cellular Automata-Markov modeling indicated stable volumetric flow but a temporal shift, including a 28.1% decrease in April rainfall from 2000 to 2040, contracting the wet season and extending dry spells. These shifts pose significant threats to agricultural and aquaculture activities, potentially exacerbating water scarcity and economic losses. The findings emphasize integrating dynamic land cover data, climate projections, and empirical runoff corrections for climate-resilient watershed management. Full article

Rice–crab co-culture systems (RC) represent promising sustainable intensification approaches, yet their nitrogen (N) cycling and optimal fertilization strategies remain poorly characterized. In this study, we compared RC with rice monoculture system (RM) across four N gradients (0, 150, 210, and 270 kg N·hm⁻²), assessing N dynamics in field water and N distribution in soil. The results showed that field water ammonium nitrogen (NH₄⁺-N) concentrations increased nonlinearly, showing sharp increases beyond 210 kg N·hm⁻². Notably, crab activity in the RC altered the N transformation and transport processes, leading to a prolonged presence of nitrate nitrogen (NO₃⁻-N) in field water for two additional days after tillering fertilization compared to RM. This indicates a critical window for potential nitrogen loss risk, rather than enhanced retention, 15 days after basal fertilizer application. Compared to RM, RC exhibited enhanced nitrogen retention capacity, with NO₃⁻-N concentrations remaining elevated for an additional two days following tillering fertilization, suggesting a potential critical period for nitrogen loss risk. Post-harvest soil analysis revealed contrasting nitrogen distribution patterns: RC showed enhanced NH₄⁺-N accumulation in surface layers (0–2 cm) with minimal vertical NO₃⁻-N redistribution, while RM exhibited progressive NO₃⁻-N increases in subsurface layers (2–10 cm) with increasing fertilizer rates. The 210 kg N·hm⁻² rate proved optimal for the RC, producing a rice yield 12.08% higher than that of RM and sustaining high crab yields, while avoiding the excessive aqueous N levels seen at higher rates. It is important to note that these findings are based on a single-site, single-growing season field experiment conducted in Panjin, Liaoning Province, and thus the general applicability of the optimal nitrogen rate may require further validation across diverse environments. We conclude that a fertilization rate of 210 kg N·hm⁻² is the optimal strategy for RC, effectively balancing productivity and environmental sustainability. This finding provides a clear, quantitative guideline for precise N management in integrated aquaculture systems. Full article

Antibiotic feeding in shrimp farming is an optional practice conducted with the aim of preventing and controlling bacterial diseases. However, the administration of antibiotics can disrupt the microbiota of both shrimp and surrounding environment, potentially compromising host health. Given the limited effective antibiotic options in aquaculture, it is crucial to evaluate the effects of florfenicol (FF) on the intestinal health of shrimp and the associated microbial communities. This study first investigated the impact of FF on the intestinal structure of Penaeus vannamei over two feeding durations (5 and 10 days), each followed by a 10-day basal diet recovery period. Simultaneously, variations in microbial communities and antibiotic resistance genes (ARGs) in both the intestine and rearing water were explored. The results showed that intestinal damage was aggravated with the extension of FF duration and gradually recovered after FF withdrawal. Significant changes in microbial composition and β-diversity were observed in both the rearing water and intestine following FF feeding. Extending the FF treatment to 10 days led to a reduced abundance of Rhodobacteraceae and an increased abundance of Flavobacteriaceae and Vibrionaceae in the intestine after 10 days of feeding the basic diet, which may pose a potential risk to shrimp health. Based on correlation analysis of ARGs, microbial communities and pathogenic bacteria, we speculated that rearing water may serve as a reservoir for ARGs dissemination compared to the shrimp intestine. These findings are of great importance for assessing the impact of administration duration under the FF therapeutic dose and highlight the potential risks associated with its overuse in shrimp farming. Full article

In aquaculture, feed production influences nutrition, performance, water quality, and overall profitability. This study evaluated the effects of three levels of internal fat (IF), resulting from the inclusion of 0%, 2%, or 4% fat in the preconditioner during extrusion, and their interaction with two extruder screw configurations: medium-shear (MS) and high-shear (HS), on kibble physical quality and extrusion parameters. Increasing IF resulted in a quadratic increase in amylose–lipid complexation under the HS configuration (p = 0.030; r2 = 0.9) and a linear reduction (p < 0.001) in specific mechanical energy (SME) with a strong negative Pearson correlation (r −0.9; p = 0.009) in both configurations. Fat inclusion also reduced mass temperature and die pressure (p < 0.05), leading to lower starch gelatinization degree (p < 0.05) from 87.9 ± 0.6% to 83.4 ± 0.3% in MS configuration and 95.6 ± 0.7 to 86.3 ± 0.8% in HS configuration, increased bulk and piece density (p < 0.001), and reduced radial expansion (p < 0.001). These changes decreased floatability (p < 0.05) and water stability, increasing mushiness (p < 0.01). Increased shear partially improved SME transfer, starch cooking, expansion, floatability, and mushiness; however, the negative effects of 4% IF could not be fully mitigated. Overall, higher IF compromised kibble structure, starch gelatinization, and floatability, while screw configuration resulted in only a limited compensatory effect. Full article

Aquaculture is a crucial global food production sector that faces challenges in water quality management, food safety, and stress-related health concerns in aquatic species. Cortisol, a key stress biomarker in fish, and Escherichia coli (E. coli) contamination in bivalve mollusks are critical indicators that require sensitive and real-time detection methods. Liquid crystal (LC)-based immunosensors have emerged as a promising solution for detecting biological analytes due to their high sensitivity, rapid response, and label-free optical detection capabilities. Therefore, this study explores the development and application of LC-based immunosensors for the detection of cortisol in artificial and real recirculating aquaculture system (RAS) samples, as well as E. coli in real contaminated water and clam samples during the depuration processes of bivalve mollusks. The biosensors exhibited the capacity to detect cortisol with a response time in seconds and a limit of detection (LOD) of 0.1 ng/mL. Furthermore, they demonstrated specificity to cortisol when tested against different interfering substances, including testosterone, glucose, and cholesterol. Furthermore, it was possible to correlate cortisol concentrations in different filtration stages and track E. coli contamination during depuration. The results confirm the feasibility of LC-based immunosensors as a user-friendly, portable, and efficient diagnostic tool for aquaculture applications. Full article

Anthropogenic climate change represents a critical and complex threat to the health and resilience of aquatic ecosystems. This review aims to critically synthesise and evaluate the synergetic and antagonistic mechanisms through which rising water temperature, the most prominent climatic factor, modulates the host–parasite relationship. The systematic literature review was conducted across a high-impact database (Web of Science), focusing on the extraction and qualitative analysis of data concerning infection dynamics and both host and parasite interactions. The findings demonstrate that thermal stress imposes a dual penalty on host–parasite systems: (1) it confers a critical thermal advantage to direct-life cycle parasites, significantly accelerating their virulence, reproduction, and infective capacity; (2) simultaneously, it severely compromises the immunocompetence and physiological resilience of piscine hosts, often through immunometabolic trade-offs and inflammatory dysfunction. This toxic synergy is the root cause of the exponential disease prevalence/intensity of parasites and fish mass mortality events, directly impacting biodiversity and global aquaculture sustainability. In contrast, it may also cause the disruption of the transmission chains to threaten complex life cycle parasites with localised extinction. We conclude that climate mitigation must be urgently recognised and implemented as a primary strategy for biological risk management to secure aquatic health and global food safety. Full article

The convergence of food insecurity, water scarcity, and environmental degradation has intensified the global search for sustainable agricultural models. Integrated Microalgal–Aquaponic Systems (IAMS) have emerged as a novel multi-trophic platform that unites aquaculture, hydroponics, and microalgal cultivation into a closed-loop framework for resource-efficient food production and water recovery. This critical review synthesizes empirical findings and engineering advancements published between 2008 and 2024, evaluating IAMS performance relative to traditional agriculture and recirculating aquaculture systems (RAS). Reported under controlled laboratory and pilot-scale conditions, IAMS have achieved nitrogen and phosphorus recovery efficiencies exceeding 95% while potentially reducing water consumption by up to 90% compared to conventional farming. The integration of microalgal photobioreactors enhances nutrient retention, may contribute to internal carbon capture, and enables the generation of diversified co-products, including biofertilizers and protein-rich aquafeeds. Nevertheless, significant barriers to commercial scalability persist, including the biological complexity of maintaining multi-trophic synchrony, high initial capital expenditure (CAPEX), and regulatory ambiguity regarding the safety of waste-derived algal biomass. Technical challenges such as photobioreactor upscaling, biofouling control, and energy optimization are critically discussed. Finally, the review evaluates the alignment of IAMS with UN Sustainable Development Goals 2, 6, and 13, and outlines future research priorities in techno-economic modeling, automation, and policy development to facilitate the transition of IAMS from pilot-scale innovations to viable industrial solutions. Full article

Water exchange capacity is critical for maintaining marine environmental quality and supporting the sustainable development of aquaculture. This study applies a high-resolution three-dimensional FVCOM hydrodynamic model coupled with the DYE-RELEASE module. The model was validated against tidal, current, and thermohaline observations. Water residence time (Tre) was used as the primary evaluation metric, supplemented by analyses of residual circulation, material diffusion, and regional variability, to systematically quantify the water exchange mechanisms and seasonal variations in the coastal waters of Changhai County under the combined influence of tides, wind forcing, and thermohaline conditions. Results show that overall residual currents in Changhai County are weak (average velocity: 0.032 m s⁻¹). However, local circulations and stagnation zones frequently develop near islands and channels, strongly influencing material diffusion. In summer, water exchange is primarily controlled by thermohaline effects, which strengthen density stratification, suppress vertical mixing, and modify circulation patterns, thereby reducing the efficiency of tide-driven exchange. Water exchange is weakest near Guanglu Island (46.6–48.6 d) and strongest near Haiyang Island (13–14 d). In winter, wind forcing dominates, enhancing vertical mixing and accelerating water renewal. Residence time in the Changshan Archipelago–Guanglu Island region decreases by 30–50% compared with summer. Overall, winter water renewal is 15–25% more efficient than in summer. This study demonstrates that water exchange in Changhai County is regulated by the combined effects of tides, wind forcing, and thermohaline dynamics. The identified spatial heterogeneity and seasonal characteristics provide a scientific basis for optimizing aquaculture planning and mitigating marine environmental risks. Full article