Integrated multitrophic aquaculture systems – Potential risks for food safety

Chitosan from Marine Amphipods Inhibits the Wilt Banana Pathogen Fusarium oxysporum f. sp. Cubense Tropical Race 4

In this work, we extracted chitosan from marine amphipods associated with aquaculture facilities and tested its use in crop protection. The obtained chitosan was 2.5 ± 0.3% of initial ground amphipod dry weight. The chemical nature of chitosan from amphipod extracts was confirmed via Raman scattering spectroscopy and Fourier transform infrared spectroscopy (FTIR). This chitosan showed an 85.7-84.3% deacetylation degree. Chitosan from biofouling amphipods at 1 mg·mL-1 virtually arrested conidia germination (ca. sixfold reduction from controls) of the banana wilt pathogenic fungus Fusarium oxysporum f. sp cubense Tropical Race 4 (FocTR4). This concentration reduced (ca. twofold) the conidia germination of the biocontrol fungus Pochonia chlamydosporia (Pc123). Chitosan from amphipods at low concentrations (0.01 mg·mL-1) still reduced FocTR4 germination but did not affect Pc123. This is the first time that chitosan is obtained from biofouling amphipods. This new chitosan valorizes aquaculture residues and has potential for biomanaging the diseases of food security crops such as bananas.

Uptake of aquaculture-related dissolved organic pollutants by marine sponges: Kinetics and mechanistic insights from a laboratory study

Besides the release of organic matter from uneaten feed and fish excreta, a considerable amount of deleterious chemicals may also end up into the marine environment from intensive aquaculture. A fraction of these pollutants remains freely dissolved and pose a threat to marine life due to increased bioavailability. Given the filter-feeding ability of sponges, we investigated the capacity of four ubiquitous Mediterranean species (Agelas oroides, Axinella cannabina, Chondrosia reniformis and Sarcotragus foetidus) in removing aquaculture-related dissolved organic pollutants. These included individual chemicals belonging to antibiotics (i.e., oxytetracycline), antifouling biocides (i.e., diuron and Irgarol 1051) and polycyclic aromatic hydrocarbons (i.e., 2,6-dimethylnapththalene, phenanthrene). The uptake of pollutants was assessed in vitro by exposing small sponge explants to each chemical for a period of 8 h. Additional "cleanup" experiments were performed for complex mixtures mimicking the dissolved organic material encountered in fish farms, such as filtrates of fish feed and excreta. All sponges exhibited a pronounced preference for lipophilic pollutants and a strong positive correlation was revealed between clearance rate and substrate hydrophobicity. Our best filter-feeder (i.e., A. oroides) was able to clear 10.0 ± 1.3 mL of seawater per hour and per gram of sponge, when exposed to 2,6-dimethylnapththalene. Active pumping was found to be the predominant mechanism dictating the assimilation of dissolved pollutants in all sponge species, as it was 3-10 times faster than pollutants' passive adsorption on sponges' pinacoderm. Additionally, the uptaken pollutants were shown to be strongly retained by sponges and they were hardly released back to seawater as a result of desorption or sponge excretory mechanisms. Our study corroborates that sponges are highly efficient in uptaking dissolved organic compounds and it offers new insights into the kinetics and mechanisms ruling this process.

Assessing pharmaceuticals in the green seaweed Ulva lactuca through a multi-residue UHPLC-ToF-MS strategy

Seaweeds have become an important asset in several sectors, including the food and feed industries, cosmetics, and pharmaceuticals, among others. Whether harvested or reared, interest in algae has been growing worldwide due to the resources they offer, including proteins, vitamins, minerals, carbohydrates, essential fatty acids, and dietary fiber, as well as sources of biologically active compounds. However, given their morphology and physiology, as well as their harvest and cultivation environments, algae are prone to the presence of hazards, including pharmaceuticals taken up from the water. Thus, to ensure human and animal safety as well as environmental health, monitoring is essential. Therefore, this work describes the development and validation of a sensitive screening and confirmatory analytical method based on ultra-high-performance liquid chromatography coupled with time-of-flight mass spectrometry (UHPLC-ToF-MS). This multi-residue method enables the determination of 62 pharmaceuticals distributed between 8 therapeutic classes and was fully validated according to Commission Implementing Regulation (EU) 2021/808.

Identification of Marine Biotechnology Value Chains with High Potential in the Northern Mediterranean Region

Marine (blue) biotechnology is an emerging field enabling the valorization of new products and processes with massive potential for innovation and economic growth. In the Mediterranean region, this innovation potential is not exploited as well as in other European regions due to a lack of a clear identification of the different value chains and the high fragmentation of business innovation initiatives. As a result, several opportunities to create an innovative society are being missed. To address this problem, eight Northern Mediterranean countries (Croatia, France, Greece, Italy, Montenegro, Portugal, Slovenia and Spain) established five national blue biotechnology hubs to identify and address the bottlenecks that prevent the development of marine biotechnology in the region. Following a three-step approach (1. Analysis: setting the scene; 2. Transfer: identification of promising value chains; 3. Capitalization: community creation), we identified the three value chains that are most promising for the Northern Mediterranean region: algae production for added-value compounds, integrated multi-trophic aquaculture (IMTA) and valorization aquaculture/fisheries/processing by-products, unavoidable/unwanted catches and discards. The potential for the development and the technical and non-technical skills that are necessary to advance in this exciting field were identified through several stakeholder events which provided valuable insight and feedback that should be addressed for marine biotechnology in the Northern Mediterranean region to reach its full potential.

Bacteria of Zoonotic Interest Identified on Edible Freshwater Fish Imported to Australia

Previous research has shown that freshwater edible fish imported into Australia are not compliant with Australian importation guidelines and as a result may be high risk for bacterial contamination. In the present study, the outer surface of imported freshwater fish were swabbed, cultured, confirmatory tests performed and antimicrobial patterns investigated. Channidae fish (Sp. A/n = 66) were contaminated with zoonotic Salmonella sp./Staphylococcus aureus (n = 1/66) and other bacteria implicated in cases of opportunistic human infection, these being Pseudomonas sp. (including P. mendocina and P. pseudoalcaligenes (n = 34/66)); Micrococcus sp. (n = 32/66); Comamonas testosteroni (n = 27/66) and Rhizobium radiobacter (n = 3/66). Pangasiidae fish (Species B/n = 47) were contaminated with zoonotic Vibrio fluvialis (n = 10/47); Salmonella sp. (n = 6/47) and environmental bacteria Micrococcus sp. (n = 3/47). One sample was resistant to all antimicrobials tested and is considered to be Methicillin Resistant S. aureus. Mud, natural diet, or vegetation identified in Sp. A fish/or packaging were significantly associated with the presence of Pseudomonas spp. The study also showed that visibly clean fish (Sp. B) may harbour zoonotic bacteria and that certain types of bacteria are common to fish groups, preparations, and contaminants. Further investigations are required to support the development of appropriate food safety recommendations in Australia.

Current Status and Future Trends in Removal, Control, and Mitigation of Algae Food Safety Risks for Human Consumption

With the rapid development of the economy and productivity, an increasing number of citizens are not only concerned about the nutritional value of algae as a potential new food resource but are also, in particular, paying more attention to the safety of its consumption. Many studies and reports pointed out that analyzing and solving seaweed food safety issues requires holistic and systematic consideration. The three main factors that have been found to affect the food safety of algal are physical, chemical, and microbiological hazards. At the same time, although food safety awareness among food producers and consumers has increased, foodborne diseases caused by algal food safety incidents occur frequently. It threatens the health and lives of consumers and may cause irreversible harm if treatment is not done promptly. A series of studies have also proved the idea that microbial contamination of algae is the main cause of this problem. Therefore, the rapid and efficient detection of toxic and pathogenic microbial contamination in algal products is an urgent issue that needs to be addressed. At the same time, two other factors, such as physical and chemical hazards, cannot be ignored. Nowadays, the detection techniques are mainly focused on three major hazards in traditional methods. However, especially for food microorganisms, the use of traditional microbiological control techniques is time-consuming and has limitations in terms of accuracy. In recent years, these two evaluations of microbial foodborne pathogens monitoring in the farm-to-table chain have shown more importance, especially during the COVID-19 pandemic. Meanwhile, there are also many new developments in the monitoring of heavy metals, algal toxins, and other pollutants. In the future, algal food safety risk assessment will not only focus on convenient, rapid, low-cost and high-accuracy detection but also be connected with some novel technologies, such as the Internet of Things (artificial intelligence, machine learning), biosensor, and molecular biology, to reach the purpose of simultaneous detection.

Integrated multitrophic aquaculture (IMTA) as an environmentally friendly system for sustainable aquaculture: functionality, species, and application of biofloc technology (BFT)

Aquaculture is one of the fastest-growing industries in the world, and its prominent role has been proven in supplying food for the growing world population. The expected growth of aquaculture requires the development of responsible and sustainable approaches, technologies, culture systems, and practices. The integrated multitrophic aquaculture (IMTA) system has been developed over the past decades. This system is based on the use of all food levels for simultaneous production of some aquaculturally species in a way that contributes to environmental sustainability (biocontrol), economic stability (product diversity and risk reduction), and social acceptance (better management operations). In IMTA, selecting suitable culture species and considering their appropriate population size is absolutely necessary to achieve an optimal biological and chemical process, improving the ecosystem health and sustainability of the industry. Biofloc technology (BFT) is closely related to the IMTA system, where the IMTA potential can be used to control suspended solids in aquaculture systems with limited water exchange. This study reviews the significance of IMTA systems, potential target species for cultivation, the relationship between BFT and IMTA, total suspended solids control, the economics of IMTA farming, and the recent findings in these fields.

An Eco-Friendly Conversion of Aquaculture Suspended Solid Wastes Into High-Quality Fish Food by Improving Poly-β-Hydroxybutyrate Production

The aquaculture industry is vital in providing a valuable protein food source for humans, but generates a huge amount of solid and dissolved wastes that pose great risks to the environment and aquaculture sustainability. Suspended solids (in short SS), one of the aquaculture wastes, are very difficult to be treated due to their high organic contents. The bioconversion from wastewater, food effluents, and activated sludge into poly-β-hydroxybutyrate (PHB) is a sustainable alternative to generate an additional income and could be highly attractive to the agricultural and environmental management firms. However, little is known about its potential application in aquaculture wastes. In the present study, we first determined that 7.2% of SS was PHB. Then, the production of PHB was increased two-fold by the optimal fermentation conditions of wheat bran and microbial cocktails at a C/N ratio of 12. Also, the PHB-enriched SS showed a higher total ammonia nitrogen removal rate. Importantly, we further demonstrated that the PHB-enriched SS as a feed could promote fish growth and up-regulate the expression of the immune-related genes. Our study developed an eco-friendly and simple approach to transforming problematic SS wastes into PHB-enriched high-quality food for omnivorous fish, which will increase the usage efficiency of SS and provide a cheaper diet for aquatic animals.

Advances in microalgal research for valorization of industrial wastewater

This review article focuses on recent updates on remediation of industrial wastewater (IWW) through microalgae cultivation. These include how adding additional supplements of nutrient to some specific IWWs lacking adequate nutrients improving the microalgae growth and remediation simultaneously. Various pretreatments strategy recently employed for IWWs treatment other than dealing with microalgae was discussed. Various nutrient-rich IWW could be utilized directly with additional dilution, supplement of nutrients and without any pretreatment. Recent advances in various approaches and new tools used for cultivation of microalgae on IWW such as two-step cultivation, pre-acclimatization, novel microalgal-bioelectrical systems, integrated catalytic intense pulse-light process, sequencing batch reactor, use of old stabilized algal-bacterial consortium, immobilized microalgae cells, microalgal bacterial membrane photobioreactor, low-intensity magnetic field, BIO_ALGAE simulation tool, etc. are discussed. In addition, biorefinery of microalgal biomass grown on IWW and its end-use applications are reviewed.

Abatement of water nutrient load in a fish culture system using the aquatic trophic levels

Integrated aquatic systems are used to decrease the nutrient loads of effluents negating the negative environmental impacts of aquacultural systems. Some of these systems have a separate algae compartment requiring high maintenance. An integrated culture system was set up with different trophic levels: algae, zooplankton, and fish. The algal tank was in-line with the fish and zooplankton components to minimize the maintenance required for the algae. A control flow-through system was also set up without the algae and zooplankton compartments. The systems were run for 6 weeks, and water temperature, pH, dissolved oxygen, NO₃ , NO₂ , NH₄ , and PO₄ concentrations were measured. A removal rate was determined for each water parameter and the densities of the algae and zooplankton species were measured in each compartment of the integrated system. The concentrations of most nutrients in the integrated system were similar to those of the control system. The density of algae increased during the first 3 weeks and remained almost stable until the end of the experiment. There was an inverse relationship between the densities of two zooplankton suggesting compensatory effects on the control of the algal bloom. The integrated system improved water quality with minimal algal culture maintenance, water exchange, and no fish mortality. PRACTITIONER POINTS: An integrated system could effectively reduce the nutrient load of water. Water replacement in the integrated system was significantly lower than that of a flow through system. The inline plankton culture tanks decreased greatly the maintenance of the system.

Review: Closing nutrient cycles for animal production - Current and future agroecological and socio-economic issues

We face an urgent and complex challenge to produce large amounts of healthful animal and plant foods for an estimated 10 billion people by 2050 while maintaining essential ecosystem services. To compound this challenge, we must do so while not further degrading our environment and conserving essential nutrients such as copper, magnesium, phosphorus, selenium, and zinc that are in short supply for fertilization. Much good research has been done, but to meet this challenge, we need to greatly increase on-farm and watershed-scale research including on-farm evaluations and demonstrations of the putative best combinations of stewardship techniques over multiple years in real-world settings, which are backed by data on nutrient inputs, soil, air, and water chemistry (fluxes) and water discharge. We also need to work with farmers, specialists, and generalists in highly creative interdisciplinary teams that resist forming silos and that use combinations of techniques linked to agroecology and industrial ecology in combination with state-of-the-art engineering. Some of these research and demonstration farms need to be in catchments prone to pollution of aquatic and terrestrial ecosystems with nitrogen, phosphorus, and other nutrients. Some promising approaches include mixed crop-livestock systems, although these alone may not be productive enough without updating to meet the dietary needs of an estimated 10 billion people by 2050. Other approaches could be state-of-the-art multi-trophic production systems, which include several species of plants integrated into production with vertebrates (e.g., ruminants, pigs, poultry), invertebrates (e.g., insects, earthworms) and fish, shrimp, or crayfish to utilize wasted feed and excreta, and recycle nutrients back to the animals (via plants or invertebrates) in the systems. To cut costs and increase desirable outputs, we must recycle nutrients much better within our food production systems and produce both animal and plant foods more efficiently as nutrients cycle through systems.

Impacts of pineapple peel powder on growth performance, innate immunity, disease resistance, and relative immune gene expression of Nile tilapia, Oreochromis niloticus

An 8-week growth trial was conducted to examine the efficacy of pineapple peel powder (PAPP) on growth rate and immunity of Nile tilapia, O. niloticus. Three hundred Nile tilapia (20.91 ± 0.11 g) were fed five diets containing different levels of PAPP at 0, 10, 20, 30 and 40 g kg^-1 PAPP, respectively. After four and eight weeks of the feeding trial, growth rates, and immune responses were tested. A challenge test using Streptococcus agalactiae and relative immune gene expression were performed after eight weeks of PAPP feeding. It was found that skin mucus and serum lysozyme, skin mucus and serum peroxidase, alternative complement, phagocytosis, and respiratory burst activities were significantly increased with the addition of PAPP. The maximum (P ≤ 0.05) innate immune values were noted in fish fed 10 g kg^-1 PAPP. Similarly, the up-regulation of IL1, IL8, and LBP gene expressions were also detected in fish fed PAPP diets, with the maximum value was found in 10 g kg^-1 PAPP fed fish. The relative percentage of survival (RPS) of Oreochromis niloticus after the challenge test were (56.00%, 72.00%, 60.00%, and 44.00%) for the 5, 10, 20 and 40 g kg^-1 PAPP diets, respectively. Fish fed the 10 g kg^-1 PAPP supplemented diet achieved the highest (P < 0.05) survival rate against S. agalactiae. Growth and feed efficiency were outstandingly (P < 0.05) enhanced in the PAPP groups. In conclusion, PAPP can be potentially used as a feed additive in Nile tilapia culture under Biofloc system.

Aquaculture industry: Supply and demand, best practices, effluent and its current issues and treatment technology

The aquaculture industry has become increasingly important and is rapidly growing in terms of providing a protein food source for human consumption. With the increase in the global population, demand for aquaculture is high and is estimated to reach 62% of the total global production by 2030. In 2018, it was reported that the demand for aquaculture was 46% of the total production, and with the current positive trends, it may be possible to increase tremendously in the coming years. China is still one of the main players in global aquaculture production. Due to high demand, aquaculture production generates large volumes of effluent, posing a great danger to the environment. Aquaculture effluent comprises solid waste and dissolved constituents, including nutrients and contaminants of emerging concern, thereby bringing detrimental impacts such as eutrophication, chemical toxicity, and food insecurity. Waste can be removed through culture systems, constructed wetlands, biofloc, and other treatment technologies. Some methods have the potential to be applied as zero-waste discharge treatment. Thus, this article analyses the supply and demand for aquaculture products, the best practices adopted in the aquaculture industry, effluent characteristics, current issues, and effluent treatment technology.

Aquaculture wastewater treatment through microalgal. Biomass potential applications on animal feed, agriculture, and energy

The use of microalgae to remediate raw effluent from brown crab aquaculture was evaluated by performing batch mode growth tests using separately the microalgae Chlorella vulgaris (Cv), Scenedesmus obliquus (Sc), Isochrysis galbana (Ig), Nannocloropsis salina (Ns), and Spirulina major (Sp). Removal efficiencies in batch growth were 100% for total nitrogen and total phosphorus for all microalgae. Chemical oxygen demand (COD) remediations were all above 72%. Biomass productivity varied from 20.9 mg L^-1 day^-1 (N. salina) to 146.4 mg L^-1 day^-1 (C. vulgaris). The two best performing algae were C. vulgaris and S. obliquus and they were tested in semi-continuous growth, reaching productivities of 879.8 mg L^-1 day^-1 and 811.7 mg L^-1 day^-1, respectively. The bioremediation of the effluent was tested with a transfer system consisting of three independent containers and compared with the use of a single container. The single container had the same capacity and received weekly the same volume of effluent as the three containers together. The remediation capacity of the 3 containers was much higher than the single one. The supplementation with NaNO₃ was tested to improve the nutrient removal microalgae' capacity, with positive results. The removal efficiencies were 100% for total nitrogen and total phosphorus and higher than 96% for COD. The obtained C. vulgaris and S. obliquus biomass were composed of 31 and 35% proteins, 6 and 8% lipids, 39 and 30% carbohydrates, respectively. The composition of these biomass suggest that it can be used as novel and sustainable ingredients in aquaculture feeds. The algal biomass of Cv and Sc were used as biostimulants in the germination of wheat and watercress, and very promising results were attained, with increases in the germination index for Cv and Sc of 175% and 48% in watercress and 84% and 98% in wheat, respectively. The biomasses of Cv and Sc were also subjected to a torrefaction process with 72.5 ± 1.7% char yields. The obtained biochars were tested as biostimulants for germination seeds (wheat and watercress) and as bio-adsorbent of dye solutions.

Testing the hydroponic performance of the edible halophyte Halimione portulacoides, a potential extractive species for coastal Integrated Multi-Trophic Aquaculture

Sea purslane Halimione portulacoides (L.) Aellen is a candidate extractive species for coastal Integrated Multi-Trophic Aquaculture (IMTA) to recycle the dissolved inorganic nitrogen (DIN) and phosphorus (DIP) wasted by excretive species. To test its suitability, saline aquaculture effluents were simulated in the laboratory using a hydroponics approach to cultivate the plants. Nutrient extraction efficiency, growth performance and nutritional profile were assessed under a range of DIN and DIP concentrations representing three different aquaculture intensification regimes and using Hoagland's solution as a control. Over a 10-week period, hydroponic units under non-limited N and P conditions displayed daily extraction rates between 1.5 and 2.8 mg DIN-N L^-1 day^-1 and 0.1-0.2 mg DIP-P L^-1 day^-1 and yielded between 63.0 and 73.0 g m^-2 day^-1 of H. portulacoides biomass. Relatively to biomass produced, H. portulacoides extracted between 2.6 and 4.2 mg DIN-N g^-1 and 0.1-0.4 mg DIP-P g^-1. The treatment with low-input of DIN and DIP (6.4 mg N L^-1 and 0.7 mg P L^-1) induced some degree of nutrient limitation, as suggested by the extremely high extraction efficiencies of DIN extraction (99%) in parallel with lower productivity. The nutritional profile of H. portulacoides leaves is comparable to that of other edible halophytes and leafy greens and could be a low-sodium alternative to salt in its lyophilized form. From the present study, we conclude that the edible halophyte H. portulacoides can be highly productive in hydroponics using saline water irrigation with non-limiting concentrations of DIN and DIP and is, therefore, a suitable extractive species for coastal IMTA in brackish waters.

Amino Acid Profile and Protein Quality Assessment of Macroalgae Produced in an Integrated Multi-Trophic Aquaculture System

Seaweeds are a recognized source of bioactive compounds and techno-functional ingredients. However, its protein fraction is still underexplored. The aim of this study was to determine the total and free amino acid profile and protein content of four seaweeds species (Porphyra dioica, Porphyra umbilicalis,Gracilaria vermiculophylla, and Ulva rigida) produced in an integrated multi-trophic aquaculture system, while assessing their protein quality. Samples were submitted to acid and alkaline hydrolysis (total amino acids) and to an aqueous extraction (free amino acids) followed by an automated online derivatization procedure, and analyzed by reverse phase-high performance liquid chromatography. Protein-, non-protein and total-nitrogen were quantified by the Kjeldahl method. Crude and true protein contents were estimated based on the nitrogen and amino acid composition. Protein quality was assessed based on the amino acids profile. Porphyra species presented the highest protein content compared to the remaining three seaweed species tested. All samples presented a complete profile of essential amino acids and a high quality protein profile, according to World Health Organization and Food and Agriculture Organization standards. Methionine and tryptophan were the first limiting amino acids in all species. Red species (Porphyra and Gracilaria) presented high levels of free alanine, glutamic, and aspartic acids. The results highlight the potential of using seaweeds as an alternative and sustainable source of protein and amino acids for human nutrition and industrial food processing.