Search Results (91)

This study assessed the presence, abundance, and characteristics of microplastics (MPs) in farmed Pacific oysters (Crassostrea gigas) and evaluated the efficacy of depuration in reducing MPs under laboratory-controlled and commercial conditions. Oysters cultivated in the Lima estuary (NW Portugal) were sampled in autumn and winter, along with adjacent surface water and sediment, to investigate potential contamination sources. MP concentrations in oysters varied temporally, with higher levels in October 2023 (0.48 ± 0.34 MPs g⁻¹ ww) than in February 2024 (0.09 ± 0.07 MPs g⁻¹ ww), while the environmental levels remained stable across dates. All MPs were fibres, predominantly transparent, followed by blue and black. Fourier-Transform Infrared Spectroscopy (FTIR) confirmed cellulose and polyethylene terephthalate (PET) as dominant polymers in oysters and environmental samples. No clear correlation was found between MPs in oysters and surrounding compartments. Laboratory depuration reduced MPs by 78% within 48 h, highlighting its potential as a mitigation strategy. However, depuration was less effective under commercial conditions, possibly due to lower initial contamination levels. These findings suggest that oysters may act as a vector for human exposure to MPs via seafood consumption. While depuration shows promise in reducing contamination, further research is needed to optimise commercial protocols and enhance the safety of aquaculture products. Full article

As the global demand for eco-friendly food ingredients grows, marine macroalgae emerge as a valuable resource for multiple applications using a circular bioeconomy approach. In this study, green macroalgae Ulva flexuosa, naturally accumulated in aquaculture ponds as a residual biomass (by-product) of shrimp and oyster farming, were investigated regarding their bioactivity, chemical composition, and antioxidant properties. The use of aquaculture by-products as raw materials not only reduces waste accumulation but also makes better use of natural resources and adds value to underutilized biomass, contributing to sustainable production systems. For this, a comprehensive approach including the evaluation of its composition and environmentally friendly extraction of bioactive compounds was conducted and discussed. Green macroalgae exhibited high fiber (37.63% dry weight, DW) and mineral (30.45% DW) contents. Among the identified compounds, palmitic acid and linoleic acid (ω-6) were identified in the highest concentrations. Pigment analysis revealed a high concentration of chlorophylls (73.95 mg/g) and carotenoids (17.75 mg/g). To evaluate the bioactivity of Ulva flexuosa, ultrasound-assisted solid–liquid extraction was performed using water, ethanol, and methanol. Methanolic extracts showed the highest flavonoid content (59.33 mg QE/100 g), while aqueous extracts had the highest total phenolic content (41.50 mg GAE/100 g). Ethanolic and methanolic extracts had the most potent DPPH scavenging activity, whereas aqueous and ethanolic extracts performed best at the ABTS assay. Overall, we show the upcycling of Ulva flexuosa, an underexplored aquaculture by-product, as a sustainable and sensible strategy for multiple value-added applications. Full article

Food security and environmental quality related to food production are global issues that need urgent solutions. Proteins are crucial for diets, and demand is growing for innovative and more environmentally sustainable sources of protein, like vegetables, microorganisms, and insects, and lab-grown food that can meet nutritional and environmental goals. This study analyzes a time series to assess the sustainability of different protein sources by evaluating their effects on emissions of greenhouse gases and the use of agricultural land while accounting for the carbon sink potential across the supply chain. The study also explores future trends in global protein sources, emphasizing shellfish as a key to achieving food security from both nutritional and environmental perspectives. By reviewing terrestrial livestock, farmed seafood, vegetal proteins, and alternative sources like insects and cultured cells, the study assesses sustainability, food security potential, and challenges from nutritional, environmental, and consumer viewpoints. We conclude that shellfish aquaculture, particularly oysters, mussels, clams, and scallops, has significant potential in enhancing food security, fostering sustainable protein consumption, reducing land use, and contributing to climate change mitigation by sequestering significant amounts of atmospheric carbon. Full article

Traditional hazard identification techniques for Vibrio parahaemolyticus often neglect the distinction between viable and nonviable bacteria in aquatic products, leading to overestimated disease risks and uncertainties in risk assessments. To address this limitation, we developed an automated PMA pretreatment instrument that integrates dark incubation and photo-crosslinking into a unified workflow, allowing customizable parameters such as incubation time, light exposure duration, and mixing speed while maintaining stable temperatures (<±1 °C fluctuation) to preserve bacterial DNA integrity. Leveraging this system, a duplex qPCR assay was optimized for simultaneous quantitative detection of V. parahaemolyticus and V. cholerae in aquatic products and environmental samples. The assay demonstrated robust performance with 90–110% amplification efficiencies across diverse matrices, achieving low limits of detection (LODs) of 10¹–10² CFU/mL in shrimp farming environment water and 10²–10³ CFU/g in shrimp (Litopenaeus vannamei) and oyster (Crassostrea gigas). Notably, it effectively discriminated viable bacteria from 10⁶ CFU/mL(g) nonviable cells and showed strong correlation with ISO-standard methods in real-world sample validation. This integrated platform offers a rapid, automated solution for accurate viable bacterial quantification, with significant implications for food safety, pathogen surveillance, and risk management in aquatic industries. Full article

This study systematically investigates for the first time the effects of dual-site co-cultivation on spectral characteristics and trace element enrichment in marine-cultured Akoya pearls from Beihai, China. Akoya pearls were cultured over a one-year period, with the final 40-day stage designated as the terminal phase. During this period, two experimental groups of pearl oysters were established: Group Y remained in Beihai for continued local cultivation and harvest, while Group B was transferred to Weihai, Shandong Province, for terminal-stage farming under different thermal conditions. A series of comparative analyses were performed using Fourier-transform infrared (FTIR) spectroscopy, ultraviolet-visible (UV-Vis) spectroscopy, Raman spectroscopy, X-ray fluorescence (XRF), and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The FTIR results revealed distinct differences between the two groups in the distribution of amide and polysaccharide functional groups, particularly around 1643 cm⁻¹ and 1100 cm⁻¹. The UV-Vis spectra of Group B displayed characteristic absorption bands at 430 nm and 460 nm, associated with the organic matrix of the nacre. Raman spectroscopy further indicated a higher abundance of organic-related vibrational features in Group B. Additionally, both XRF and LA-ICP-MS analyses consistently showed significant differences in the concentrations and distributions of trace elements, particularly copper (Cu), cobalt (Co), and zinc (Zn). The findings demonstrate that the dual-site co-cultivation mode significantly impacts both the organic composition and trace element enrichment patterns in seawater Akoya pearls. This research provides valuable references for optimizing environmental parameters in pearl cultivation processes. Full article

The Pacific oyster, Crassostrea gigas, is an important commercially farmed species in Korea. C. gigas exhibits low genetic diversity in wild populations in Korea. To address this, we bred Japanese broodstock for more than five generations and released them into two populations to increase genetic diversity. We also assessed whether this improvement was achieved by comparing them with a control population. In this study, we analyzed genetic diversity using 16 microsatellite loci of C. gigas. The observed heterozygosity H_O in the farmed population ranged up to 0.494, while in the wild population, it was 0.437. The farmed population had the highest genetic diversity, but the effective population size was low (105). The PD population size for resource creation was 403, which was higher than that of GH. The genetic structure was divided into two groups with K = 2. The first group consisted of the BR population, while the second group included the GH, GW, and PD populations. Therefore, we confirmed significant genetic differences between the farmed, wild, and resource creation populations. This study provides essential genetic information for future fishery resource development and conservation of C. gigas. Full article

In this study, we explored the ability of Gracilaria vermiculophylla coupled with Crassostrea hongkongensis to purify aquaculture effluent by analysing the purification of intensive shrimp farming effluent using G. vermiculophylla under different environmental conditions. After determining the optimal conditions, we further investigated the capability of the G. vermiculophylla and oyster coupling in intensive shrimp farming effluent purification. The shrimp farming density was 200 individuals per cubic metre (equivalent to 0.2 individuals per litre). The optimal environmental parameters were as follows: oyster biomass of 4.5 kg·m⁻³, G. vermiculophylla biomass of 2 kg·m⁻³, water temperature of 25–30 °C, and salinity of 15–30‰; the total inorganic nitrogen, PO₄³⁻-P, total nitrogen, and total phosphorus removal rates were 59.56%, 97.43%, 63.67%, and 76.25%, respectively, with G. vermiculophylla increasing in weight by 31.01%. For every 1 kg increase in the dry weight of G. vermiculophylla, 36.89 g of N and 12.40 g of P could be absorbed from the effluent. Our findings indicate that the coupling of G. vermiculophylla with oysters greatly contributed to the purification of effluent from intensive shrimp farming and can, thus, be used for treating intensive shrimp farming effluent. Full article

Nuclear power plants utilize great quantities of seawater to cool down, resulting in substantial warm water discharges that may affect nearby fisheries and marine ecosystems. This study focused on Crassostrea (Magallana) ariakensis, a commercially farmed oyster species along the southern coast of China. To evaluate the thermal impacts of warm water discharges from nuclear power plants, indoor simulations replicated seasonal water temperature conditions near coastal facilities (26 °C in spring and autumn, 16 °C in winter, and 30 °C in summer). We conducted thermal tolerance static and dynamic experiments, along with a 51-day long-term experiment on suitable growth under different acclimation temperatures. The thermal effects of warm water discharges on C. ariakensis were systematically assessed through survival, growth, digestibility, and nutritional quality. The results showed that the discomfort temperature range of C. ariakensis was (48.6 ± 1.2)~(58.9 ± 3.0) °C, the critical thermal maxima (CTM) value range of C. ariakensis was (51.6 ± 1.4)~(61.2 ± 2.2) °C, and the incipient lethal temperature (ILT₅₀) of C. ariakensis was 45.61 °C, 53.71 °C, and 55.90 °C, respectively; all these values increased gradually with the rise of acclimation temperature. After the 51-day long-term experiment on suitable growth, the temperature increase of 1 °C, 2 °C and 4 °C did not affect the soft tissue wet weight, condition index, moisture content, and fat content of C. ariakensis, but the amylase activity in digestive gland tissue decreased in different temperature experimental groups. The experimental results show that the influence of temperature rise on the growth and physiological metabolism of C. ariakensis is limited. However, based on the normal habitat temperature in summer, the long-term effects of temperature rise caused by warm water discharges need to be paid attention to. Full article

Aquaculture plays a crucial role in meeting the needs of a growing human population and achieving the sustainable development goals outlined in Agenda 2030. However, it is essential that this sector grows sustainably. In this study, we hypothesized that environmental sustainability decreases as the trophic level of farmed species increases and that it is higher in integrated systems compared to monocultures. To test these hypotheses, we conducted a comparative analysis of the environmental sustainability indicators of some aquaculture systems, including the farming of primary producers, filter feeders, and low-trophic phagotrophs. We compiled secondary data on eighteen environmental sustainability indicators from seven aquaculture systems. Five are monocultures, including the farming of macroalgae (Hypnea pseudomusciformis), oysters (Crassostrea gazar) in a tropical environment, oysters in a subtropical environment, as well as tambatinga (hybrid Colossoma macropomum × Piaractus brachypomus) and tambaqui (Colossoma macropomum). Additionally, two are integrated systems: tambaqui raised in hapa nets (small cage-like enclosures) within Amazon river prawn (Macrobrachium amazonicum) ponds, and tambaqui and prawns cohabitating freely in the same ponds. A benchmark tool was utilized to establish reference values for comparing indicators between the systems, and a method was developed to create environmental sustainability indices that integrate all indicators. Environmental sustainability tends to decrease as trophic levels rise, supporting the initial hypothesis. However, the data revealed that Integrated Multi-Trophic Aquaculture (IMTA) systems ultimately have lower environmental sustainability than monocultures, which was contrary to our expectations. Algae and oyster farming were found to be more environmentally sustainable than low-trophic fish farming systems. Among these, the integrated systems did not demonstrate significantly greater sustainability than the monocultures, as initially anticipated. To gain a comprehensive understanding of sustainability, further research on the social and economic sustainability of these systems is necessary. Full article

Oyster mushrooms are regarded as one of the most significant edible mushrooms in terms of commercial value because of their rich nutritional profile. Many bioactive extracts from Pleurotus species have been found to exhibit antitumor and antioxidant activities. However, to grow oyster mushrooms in this study, the pasteurized Cenchrus fungigraminus was used as culture material, a type of grass that proliferates and has a high root growth rate. It contains high levels of sugar and protein and yields a large amount of biomass. Because of these characteristics, it is considered an efficient and cost-effective energy crop with various applications, including phytoremediation and fodder production. A pasteurization technique for this grass that is suited for the simplest formulation is simple and cost-effective for growing oyster mushrooms on small farms. This study used pasteurized Cenchrus fungigraminus as a substrate to grow three mushroom species: Pleurotus ostreatus, Pleurotus pulmonarius and Pleurotus florida. The aim was to evaluate their enzyme activities, growth rate, and yields. The findings demonstrated that the average growth rate of three species grown in pasteurized C. fungigraminus was between 25 days and 36 days. Therefore, the mycelium growth rate of P. ostreatus was faster than other pleurotus species in this study. The highest biological efficiency was recorded with P. ostreatus at 78.23%, then P. pulmonarius at 59.88, and lastly, 39.66% P. florida. The changes in five enzyme activities in distinct developmental stages of three different pleurotus species were evaluated. Therefore, the laccase had the highest peak with 13.8 U/g on the 20th day during the growth phase and gradually decreased to the fruiting body stage of P. ostreatus. The expression of manganese peroxidase reached the highest activity of 3.6 U/g in P. ostreatus compared to P. florida and P. pulmonarius on the 10th day. The expression of other enzymes varied between species and developmental phases. The results indicate the usefulness of pasteurized C. fungigraminus for cultivating Pleurotus species and expression enzyme activity in different Pleurotus species. Full article

Oyster farming plays a crucial role in sustainable food production due to its high nutritional value and relatively low environmental impact. However, in a scenario of increasing production, it is necessary to consider the issue of plastic use as a limitation to be addressed. A life cycle assessment (LCA) was conducted on oyster farming in La Spezia (Italy) as a case study, utilizing 1 kg of packaged oysters as the functional unit. Fossil-based plastics and wooden packaging were identified as the primary environmental concerns. To analyze potential strategies for reducing the environmental impact of oyster farming, alternative scenarios were considered wherein fossil-based materials were replaced with bio-based materials. Specifically, this study examined the substitution of the current packaging, consisting of a wooden box and a polypropylene (PP) film, with a fully recyclable PP net. Additionally, polylactic acid (PLA), polyhydroxyalkanoates (PHAs), and bio-based polyethylene terephthalate (Bio-PET) were proposed as alternatives to virgin high-density polyethylene (HDPE) and PP for buoys, oyster bags, and boxes. Among the scenarios analyzed, the sole effective strategy to reduce the impact of plastics on the process is to replace them with PHA. In the other cases, the high energy consumption of their non-optimized production renders them disadvantageous options. However, the assessment must include the effects of degradation that traditional plastics can have in the marine environment, an aspect that potentially renders natural fibers more advantageous. The use of PP net packaging has demonstrated high efficacy in reducing impacts and provides a foundation for considering the need to combine sustainability and marketing with current legislation regarding food packaging. Full article

Bivalve molluscs are filter-feeding organisms, capable of concentrating pathogenic microorganisms from the surrounding environment, thus contributing to the spread of viral pathogens, which they can transmit to humans, especially if eaten raw or undercooked. Although norovirus (NoV) and the hepatitis A virus (HAV) are considered the most common causes of foodborne infections, in recent years, other viruses with a zoonotic potential have been identified in shellfish, such as the hepatitis E virus (HEV), astrovirus (AsV), and aichi virus (AiV). The aim of the study was to investigate the presence of classical and emerging pathogenic enteric viruses in oysters (Crassostrea gigas) and mussels (Mytilus galloprovincialis) from a mollusc farming area in the northwest of Italy, between April 2022 and March 2023. In the period considered, a total of 168 samples (84 oysters and 84 mussels) were analysed. The prevalence of NoV was highest, with 32.7% (55/168) positive samples, followed by 18.4% (31/168) for AsV and 19.6% (33/168) for AiV. This study revealed, for the first time, the presence of AsV and AiV in molluscs farmed in this sea area. All the samples tested were negative for HAV and HEV. The emergence of new enteric viruses like AiV and AsV in bivalve molluscs underscores the importance of improving surveillance and environmental monitoring methods, particularly in shellfish production areas. Full article

White spot syndrome virus (WSSV) poses a major risk to shrimp aquaculture, and filter-feeding bivalves on shrimp farms may contribute to its persistence and transmission. This study investigated the bioaccumulation and vector potential of WSSV in Pacific oysters (Crassostrea gigas), blue mussels (Mytilus edulis), and manila clams (Venerupis philippinarum) cohabiting with WSSV-infected shrimp. Sixty individuals of each species (average shell lengths: 11.87 cm, 6.97 cm, and 5.7 cm, respectively) cohabitated with WSSV-infected shrimp (Penaeus vannamei, average body weight: 16.4 g) for 48 h. In the experiments, bivalves accumulated WSSV particles in both the gill and digestive gland tissues, with the digestive glands exhibiting higher viral load (average viral load, 3.91 × 10⁴ copies/mg), showing that the viral concentrations in bivalve tissues are directly influenced by seawater WSSV concentrations, reaching levels sufficient to induce infection and 100% mortality in healthy shrimp using tissue homogenates. After a 168 h release period in clean water, the WSSV levels in bivalve tissues decreased below the detection thresholds, indicating reduced transmission risk. These results highlight the role of bivalves as temporary reservoirs of WSSV in aquaculture settings, with the transmission risk dependent on the viral concentration and retention period. Our findings suggest that the management of bivalve exposure in WSSV-endemic environments could improve the biosecurity of shrimp farms. Full article

To address the challenges of labor-intensive and costly manual oyster spat insertion in longline-suspended farming, an automated oyster spat insertion device was designed based on negative pressure suction and bundling fixation technologies. Using this device as the experimental platform, a three-factor, three-level Box–Behnken experiment was conducted, with fixation mechanism inclination, negative pressure suction cup span, and horizontal distance between turnover and fixation mechanisms as the experimental factors. The performance of the device was evaluated using the effective fixation rate and damage rate as the experimental indicators. The quadratic polynomial regression models were established to assess the impact of these factors on operational performance, while the response surface method was employed to analyze the interaction effects between factors. Parameter optimization and experimental validation were also performed. The results indicate that the factors affecting the effective fixation rate, in order of significance, are as follows: fixation mechanism inclination, horizontal distance between turnover and fixation mechanisms, and negative pressure suction cup span. For the damage rate, the order of significance is as follows: fixation mechanism inclination > negative pressure suction cup span < horizontal distance between turnover and fixation mechanisms. The optimization results show that when the fixation mechanism inclination is set at 43°, the negative pressure suction cup span at 27 mm, and the horizontal distance between turnover and fixation mechanisms at 179 mm, the effective fixation rate reaches 92.08%, and the damage rate is 4.71%. The relative errors between the measured and model-predicted values are less than 5%, indicating that the regression models are reliable. This research provides valuable insights for advancing the mechanization of the oyster farming industry and replacing manual labor with mechanized equipment. Full article

Warm water temperature is a risk factor for recurrent mass mortality in farmed Pacific oysters Crassostrea gigas caused by Ostreid herpesvirus-1, but there is little information on environmental conditions when the disease first appears in a region—the index case. Environmental conditions between four index cases in Australia (2010, 2013, 2016 and 2024) were compared to provide insight into possible origins of the virus. Each index case was preceded by unusually low rainfall and higher rates of temperature change that could increase oyster susceptibility through thermal flux stress. Water temperature alone did not explain the index cases, there being no consistency in sea surface, estuary or air temperatures between them. Tidal cycles and chlorophyll-a levels were unremarkable, harmful algae were present in all index cases and anthropogenic environmental contamination was unlikely. The lack of an interpretable change in the estuarine environment suggests the recent introduction of OsHV-1; however, viral emergence from a local reservoir cannot be excluded. Future events will be difficult to predict. Temperature flux and rainfall are likely important, but they are proxies for a range of undetermined factors and to identify these, it will be necessary to develop comprehensive protocols for data acquisition during future index cases. Full article