Integrated Multi-trophic Aquaculture Research Articles

Ecological implications of unintentional aquaculture escapees: an overview of risks, remediation strategies and knowledge gaps in the aquaculture sector of India and riparian East African countries

The global expansion of aquaculture has driven significant technological advancements, including raceways, Integrated Multitrophic Aquaculture (IMTA) and marine offshore cages. However, unregulated aquaculture escapees pose a severe threat to aquatic biodiversity, acting as a potential time bomb for the entire ecosystem. Addressing this issue requires a comprehensive understanding of the impact of unintentional escapees on aquatic ecosystems, particularly in India and riparian East African countries (Kenya, Uganda, and Tanzania). Using an exploratory research design drawing from various peer-reviewed sources, this study outlines the dynamic growth of aquaculture in these countries, identifies high-impact escape incidents, and correlates risks and remedies with global cases, especially in regions such as Norway, Scotland, Ireland, Colombia, and the United States, where serious incidents of aquaculture escapees have been reported. The research categorizes aquaculture development trends, discusses mechanisms of escapee impact, proposes remedies, assesses methods and inferential strength, and highlights gaps in the existing literature. The study revealed complex ecological shifts caused by aquaculture escapees from invasive non-native fish species, affecting predation, competition, and genetic diversity. Escaped fish from aquaculture facilities pose a significant threat to aquatic biodiversity, especially in the study regions. The escalating risk of unintentional escapes was highlighted in India and three East African countries. To mitigate this, the study proposes integrating escapee management into national fisheries systems, amending fisheries laws, holding fish farmers accountable for aquaculture system failure, and developing comprehensive regulations for non-native species in aquaculture within the study regions. It is recommended to standardize the planning for aquaculture facilities and implement emergency plans, training, local mobilization and further research on the impact thresholds of aquaculture escapees in the study regions. Ecological education in aquaculture communities and the recognition of the role of translational scientists are crucial for the dissemination of knowledge. Urgent government action is needed to address unreported aquaculture escapes, preventing further ecosystem degradation and ensuring global aquaculture sustainability.

Exploring the optimal integrated multi-trophic aquaculture (IMTA) patterns benefiting culture animals and natural water environment

Despite bringing various benefits, rapid developments in aquaculture have contributed to the eutrophication of natural water environments. Therefore, it is imperative to mitigate nutrient load in natural water bodies while ensuring sustainable development of aquaculture. On the basis, we proposed an integrated multi-trophic aquaculture (IMTA) system, which considered a perfect solution and constructed an optimised IMTA pattern. Silver and bighead carps and freshwater pearl mussels were used as purification organisms. Six experimental groups were established for a land-based enclosure experiment: giant freshwater prawn monoculture group (G); giant freshwater prawn and freshwater pearl mussel polyculture group (GH2); giant freshwater prawn and silver and bighead carp polyculture group (GSB); giant freshwater prawn, freshwater pearl mussel and silver and bighead carp polyculture groups (GSBH1, GSBH2 and GSBH3) in different densities of freshwater pearl mussels. Each group had four replicates. Control of cyanobacterial blooms, productivity index, outputs of total nitrogen and total phosphorus and microbial community composition were studied and compared in different culturing patterns. Results showed that the GSBH1 group had the most obvious comprehensive advantages in the above four aspects (no cyanobacterial bloom occurred; the best comprehensive productivity index of giant freshwater prawn; the abundance of beneficial microorganisms in sediments was the highest; reduced phosphorus emissions in tailwater by 60.34%; the utilisation rates of nitrogen and phosphorus increased by 10.99% and 13.05%, respectively). Even so, however, the GSBH1 group might not be the most optimal IMTA pattern in practice because the mortality rate of the mussels reached 12.33% and the weight gain was −3.66%. Additionally, the presence of freshwater pearl mussel at its lowest density in this experiment had exhibited detrimental impacts on the growth of silver and bighead carps. Therefore, the most optimal IMTA pattern needs to be determined by further research.

Climate impacts and adaptation strategies for coastal erosion, aquaculture, and tourism along the Adriatic side of Apulia region

This study addresses the imperative need for adaptation strategies to climate impacts in coastal areas, particularly vulnerable to climate change effects. Under the Interreg project “AdriaClim,” our research aims to provide a comprehensive account of predicted climate impacts and corresponding adaptation measures for three key sectors for the coastal economy of the Puglia region (Southern Italy): coastal erosion, aquaculture, and tourism. Analyzing regional climate projections, predicted climatic anomalies for Apulia have been delineated. Together with a comprehensive description of the investigated sectors, the expected sectoral climate impacts have been identified. The respective adaptation measures for each sector have been evaluated in terms of coherence with the studied context and effectiveness, among those proposed in the literature. In aquaculture, climate change may influence ecosystem structure, functionality, production cycles, infrastructure, and organism physiology. Integrated multitrophic aquaculture (IMTA) emerges as a solution to enhance the resilience of Apulian aquatic production systems to climate change. For coastal tourism, the vulnerability to various climate impacts is emphasized. These impacts can directly influence tourist flows or indirectly alter the attractiveness of the Apulian Adriatic coast. Given the sector's strong ties to anthropic, natural, and cultural elements, a comprehensive adaptive approach proves most effective. Concerning coastal erosion, results underscore the prevalence of numerous stretches of eroding low coastline, with future projections indicating scenarios of widespread retreat along the southern Adriatic coast. Consequently, protective, and coastal management measures become imperative. The analyses and the obtained results serves as a valuable knowledge framework essential for formulating a climate change adaptation plan for the Apulian Adriatic coast, aligning with the regional authorities' orientations.

A stakeholders’ perception: Turkish aquaculture sector under COVID-19 pandemic effect with consideration of anthropogenic stressors

The Turkish aquaculture sector is growing very rapidly, yet the impacts of the pandemic on both sea and inland water operations remain unclear. To provide a knowledge baseline based on stakeholders, we carried out a rapid assessment in the present study. The primary objectives were to evaluate the stakeholder perceptions regarding economic loss attributed to the COVID-19 pandemic, the effectiveness of implemented mitigating measures, and the overall impact on health and wellbeing. The study also asked respondents about the disruption and loss they felt as a result of the consequences of anthropogenic stresses over the previous ten years. Out of 195 survey participants, only 107 completed and were assessable (73 from land-based farms and 34 from sea-based farms). Ninety percent of those surveyed said they had suffered various levels of financial loss as a result of the COVID-19 epidemic, especially in land-based systems. Loss of market and clients appeared to be a major issue, particularly for land-based farmers. To deal with the problem, sea-based farmers tried to develop integrated aquaculture systems, change farming systems and increase the link with scientists, whereas land-based operations preferred changing marketing methods such as direct sales to consumers, substitute market and processing methods to deal with the problem. The respondents reported higher loss associated with anthropogenic stressors, namely diseases and heat waves. Our results suggest that the decision-makers should be more prepared for such unexpected crises and take anthropogenic stressors into account when designing future recovery strategies for this productive sector.

Sludge from sea-based Atlantic salmon (Salmo salar L.) production: quantification, composition, and potential application in integrated multi-trophic aquaculture

Future growth of Atlantic salmon (Salmo salar L.) in Norway is tied to finding solutions for major ecological challenges connected to salmon lice, escapees, and nutrient emissions from sea cages. At the same time, nutrient-rich sludge from salmon production comprises a valuable resource for the cultivation of lower trophic species using an integrated multi-trophic aquaculture (IMTA) approach. This study aimed to quantify the sedimentation of aquaculture sludge under sea cages of an Atlantic salmon aquaculture site and to qualify the composition of this sludge. Additionally, the study evaluated the hypothetical use of sludge from sea-based aquaculture as a feed source for polychaetes Hediste diversicolor. Using sediment traps, sludge samples were collected under two different Atlantic salmon sea cages, at two different depths, and three different sampling dates. Subsequently, they were quantified, and their composition was assessed with regards to carbon (C), nitrogen (N), phosphorus (P), lipid, fatty acid (FA), protein, amino acid (AA), and ash content as well as elemental ratios and composition of FAs and AAs. The quantity of collected sludge was significantly different between sea cages, with a strong positive correlation between feed input and collected sludge (R2 = 0.98, p < 0.05). Sampling depth did not affect the quantity of collected sludge in the sediment traps (2215 ± 480 mg DW day−1), and no significant difference in sedimented sludge as a proportion of theoretically produced sludge (12.94 ± 2.16%) was found when comparing the different cages and sampling depths. Furthermore, the composition of collected sludge was similar at all sampling points. The overall nutritional value was lower compared to sludge from land-based aquaculture; regardless, sludge from sea-based salmon production can in theory be considered a potential feed resource to be used for the production of polychaetes H. diversicolor.

Growth and survival of milkfish (Chanos chanos), tiger prawns (Panaeus monodon), and oysters (Crassostrea sp.) in integrated multi-trophic aquaculture (IMTA) system with varying stocking densities

Integrated Multitrophic Aquaculture System (IMTA) is a sustainable approach to aquaculture, utilizing ecosystem dynamics by integrating various species. This study examined the growth and survival of milkfish (Chanos chanos), tiger shrimp (Penaeus monodon), and oysters (Crassostrea spp.) in IMTA systems with different stocking densities. A 30-day experiment using a nonfactorial-completely randomized design with four treatments and three replications was conducted. The results showed that the implementation of IMTA had no significant impact on the survival rate of milkfish, tiger prawns or oysters in all treatments. However, important variations in growth parameters were observed. Milkfish and tiger prawns showed the highest weight and length gain in treatment B, followed by treatments A, C, and D. Similarly, oysters showed optimal growth in treatment B, followed by A, C, and D, based on weight gain, length, width, and shell thickness. Throughout the study, the physicochemical parameters of the water remained within acceptable ranges, thus supporting ideal growth conditions for the cultured species. These findings underscore the potential of IMTA to increase aquaculture productivity while upholding the principles of environmental sustainability. By optimizing stocking density and encouraging species diversity, IMTA presents a promising avenue for advancing integrated aquaculture practices, in line with the FAO's blue economy concept and ecosystem approach to aquaculture. Future research should concentrate on refining the IMTA system and evaluating its long-term ecological and economic consequences.

Performance of An Aerated Wastewater Stabilization Pond for the Treatment of Cultivation Wastewater of Pacific White Shrimp (Litopenaeus vannamei) Grow-out Ponds

Pacific white shrimp (Litopenaeus vannamei) is a major cultivated crustacean species whose aquaculture production has doubled in the last decade. The implementation of shrimp pond systems using closed or intensive methods is widely carried out. However, wastewater produced by intensive shrimp farming may cause environmental effects. This study is aimed to evaluate the feasibility of the aerated wastewater stabilization pond to treat the cultivation wastewater. The physicochemical parameters monitored were temperature, pH, salinity, ammonia, nitrite, nitrate and phosphate. In the case of this study, almost all physicochemical parameters of the water coming out of the aerated wastewater stabilization pond are suitable for use as input water for integrated multitrophic aquaculture (IMTA). Temperature, pH, salinity, nitrite, nitrate, and phosphate were 27.1°C to 32.2°C, 7.86 to 8.79, 30 ppt to 34 ppt, 0.003 mg/L to 0.068 mg/L, and 0.19 mg/L to 1.31 mg/L, respectively. Only ammonia concentration significantly fluctuated in the range of 0.44 mg/L to 12 mg/L.

Growth Performance and Environmental Quality Indices and Biomarkers in a Co-Culture of the European Sea Bass with Filter and Deposit Feeders: A Case Study of an IMTA System

This study aimed to evaluate the efficiency of an integrated multi-trophic aquaculture (IMTA) system comprising co-cultured fed fish and organic extractive species representing three distinct trophic levels as well as the impact and potential utilization of two commercially available fish feeds made up of 35% fish meal (FM) and 20% fish meal (LFM) ingredients, using a multi-indicator assessment approach. Significant alterations were observed in growth performance indicators (GPIs), water and sediment quality indices, toxicity tests and biomarkers within the IMTA system. The fish survival, weight gain (WG), and specific growth rate (SGR) were higher in the IMTA system with significantly lower feed conversion ratios (FCRs) and higher feed efficiency (FE) in comparison to the fed fish monoculture system. Yet, organic filter feeders displayed 100% survival, and increased shell growth, while deposit feeders exhibited successful survival and significant weight gain. In the comparison between FM-IMTA and LFM-IMTA, fed fish in FM-IMTA showed higher WG, SGR, and FE with lower FCR. Environmental parameters like temperature, oxygen, and nutrient concentrations fluctuated but generally improved in the IMTA system, indicating lower mesotrophic conditions. Sediment fatty acid profiles differed between systems and toxicity assessments, which suggested a lower impact in IMTA and FM-IMTA systems. The sediment microbial community displayed high similarity within IMTA systems and between FM-IMTA and LFM-IMTA. These findings underscore the potential of IMTA systems for sustainable aquaculture, emphasizing improved growth performance and reduced environmental impact, particularly when using fish meal feeds.

Yield, nutrients uptake and lipid profile of the halophyte Salicornia ramosissima cultivated in two different integrated multi-trophic aquaculture systems (IMTA)

The nutrient removal, biomass production and nutritional value of the halophyte Salicornia ramosissima were evaluated in the context of an Integrated Multi-Trophic Aquaculture (IMTA) system. The experiment consisted of an indoor fish RAS whose effluent was used to feed two different halophyte hydroponic systems: a Nutrient Film Technique (NFT) system or a Deep Water Culture (DWC) system. The highest yield of S. ramosissima was observed in the DWC (320 g m−2 day−1), this system showed significantly higher yields compared to the NFT. Both hydroponic systems were effective in removing nutrients from the fish RAS wastewater, contributing to the wastes valorization process. Maximal nutrient uptake efficiencies were: 82.8% and 68.6% NO3− in the DWC and the NFT, respectively; 72.6% PO43− in the DWC and 82.9% in the NFT; 63.6% NO2− in the DWC vs 56.4% in the NFT; and 89.2% NH4+ in the DWC vs 94.1% in the NFT. The lipid profile of the halophytes in the DWC was analysed. The total lipid content ranged from 2.99% to 3.83%. The fatty acids (FA) profile in the leaves was dominated by polyunsaturated fatty acids (about 66%), which were represented by α-linolenic acid (41%) and linoleic acid (24%), followed by saturated fatty acids (28%) with palmitic acid (22%) as the major component. A small component of monounsaturated fatty acids accounts for about 12% of total FA. Regarding lipid classes, pigments were the most abundant compounds followed by glycolipids, phospholipids, flavonoids and sterols. The study supports the potential of S. ramosissima to valorise aquaculture wastes and its high nutritional interest. The experimental systems minimized waste and maximized resources utilization. Such integrated approaches can contribute to the sustainability and resilience of aquaculture systems while providing additional economic opportunities through the production of high value halophyte products.

Integrated multi-trophic aquaculture of steelhead trout, blue mussel and sugar kelp from a floating ocean platform

Over the last several decades, the commercial fishing fleet in New England has been subjected to increasingly restrictive management measures established to rebuild declining stocks. This has limited fishing opportunities and significantly reduced the inshore small vessel fleet. To help support New Hampshire (NH) commercial fishermen, an extension program was developed by the University of New Hampshire (UNH) and NH Sea Grant to train fishers on small-scale integrated multi-trophic aquaculture (IMTA) growing steelhead trout, blue mussels, and sugar kelp together, with the goal of providing alternative income sources and increasing local food production without adding significant levels of nitrogen to the environment. A total of 416 kg of steelhead trout, 3072 kg of blue mussels, and 638 kg of sugar kelp were produced in this study. The steelhead trout released an estimated 25.1 kg of N into the environment, while the mussels and kelp together extracted an estimated 41.5 kg N for a net reduction of ∼16.4 kg N from the ecosystem. There was no observed negative impact on local water quality at any point during the trial. Overall, this program demonstrated a culture method that can positively impact the ecosystem, while providing the fishermen with a new skill set that they could adopt either part time or full time, to provide additional income.

Maximum entropy modelling to identify optimal locations for an IMTA system comprising Sparus aurata, Mytilus galloprovincialis and Ulva rigida on Europe’s Atlantic coastline

Meeting the resource demand for an increasing human population has led to the emergence of the aquaculture industry as the fastest growing sector for food production worldwide. Modern finfish aquaculture has raised environmental concerns and, to address this, Integrated Multi-Trophic Aquaculture (IMTA) has gained popularity as a means to minimise environmental impacts. This is done by culturing extractive species alongside fed species to utilise excess nutrients and enhance their own growth. The current study, based within the Atlantic Area of Europe, identified suitable habitats for the three species Sparus aurata, Mytilus galloprovincialis and Ulva rigida, for use in a new IMTA system. Models were created using MaxEnt software and input into GIS software (ArcMap 10.8.1) for analysis. For all species, the AUC results in the model were &gt;0.9, with values of 0.931 (S. aurata), 0.928 (M. galloprovincialis) and 0.939 (U. rigida), demonstrating significant predictive power. Jackknife testing of the model for each species identified the mean sea surface temperature (°C) and Chlorophyll A (mg m–3) concentration as the two most important variables. The model showed that areas of &gt;50% suitability could be found throughout the study area, although the most suitable sites were in coastal areas in more southern latitudes. To identify the feasibility of establishing an IMTA system in different areas, the shipping density, MPA status and the locations of harbours were added to the maps for further consideration. Using this study, and the species-specific information identified by the model, the aquaculture industry will be better equipped to identify potential IMTA sites and integrate these systems into the EU market for sustainable production.

The Combination of Aquatic Species in Integrated Multi-Trophic Aquaculture with Paddy in Brackish Water: An Investigation of Feed Utilization Performance

This study investigated the performance of artificial feed in the Integrated Multi Trophic Aquaculture (IMTA) system through a combination of milkfish, tiger shrimp, and clam involving paddy in brackish water. The three combination groups (C) and triplicate including milkfish and paddy (C-2), milkfish, tiger shrimp, and paddy (K-3), and milkfish, tiger prawns, clams, and paddy (C-4) were examinated for 80 days on a model sheeting pond designed to have a volume of 280 L and a density of 30 individuals. Meanwhile, 30 clumps of paddy were maintained through the floating method which is constructed from bamboo with an area of 1 m2. Feeding 3 times a day with 5% of biomass resulted a mean Feed Conversion Ratio (FCR) and Index Profit (IP) of 2.1 and 2.0 for C-2, 2.0 and 2.9 for C-3, and 1.9 and 3.1 for C-4, respectively. The results showed that the best trend pattern were the combination of C-3 species which were statistically found to have a significant effect (P&lt;0.05) on FCR and IP performances. The findings of current study have practical significance for the expansion of co-culture of paddy and aquatic animals in brackish water which important by ecologically, biologically, and economically.

Nitrogen excretion by the lobsters Panulirus ornatus and Thenus australiensis and uptake by the brown algae Sargassum siliquosum: Implications for integrated recirculated aquaculture systems

Farming extractive species such as macroalgae that take up nitrogen (N), with fed species (e.g., lobsters, finfish, prawns) is termed integrated multi-trophic aquaculture (IMTA). In recirculating aquaculture systems (RAS), high concentrations of nitrogenous waste can become toxic to the fed species and macroalgae offers a method of mitigating N waste. To utilise macroalgae as a biofilter for N waste, an understanding of their N ecophysiology of both the fed and extractive species is needed. In this study we first determine the ammonium and urea excretion rates for emerging aquaculture candidates the tropical rock lobsters, Panulirus ornatus (TRL) and slipper lobster, Thenus australiensis (SL). Using multiple flask uptake experiments, we then determined the N ecophysiology of the tropical brown macroalga, Sargassum siliquosum, to assess its potential use as a biofilter in a lobster RAS. Routine (basal) N excretion was predominantly ammonium with only a minor contribution of urea (8 and 13% for TRL and SL respectively). For both lobster species, ammonium and urea excretion substantially increased post-prandial, peaking at levels 3.6 times greater than basal amounts for TRL and 3.2 times greater for SL, and remained elevated for between 32 and 38 h. Uptake of both ammonium and nitrate by S. siliquosum showed saturating kinetics, where the kinetic parameter Vmax is the maximum rate of uptake, Ks is the half-saturation constant and the Vmax:Ks-ratio is a proxy for the algae's affinity of uptake for that respective nutrient: for ammonium Vmax = 110.9 μmoles g−1 dry weight (DW) h−1 and Ks = 37.9 μM and for nitrate Vmax = 152.7 μmoles g−1 DW h−1 and Ks = 58.52 μM. Urea uptake was highly variable with both positive and negative (i.e. urea release from tissue) rates recorded; when positive values were considered, Vmax = 55.5 μmoles g−1 DW h−1 and Ks = 17.65 μM. We used uptake and excretion rates from our study to derive a unit mass stocking ratio of algae to lobster (algae: animal) to offset N pollution in RAS. The ratios of TRL to algae to offset NH4+ and urea post-prandial were 5.15E-04 and 3.09E-04 respectively and for SL, 4.46E-04 and 6.31E-04 respectively. The findings serve as a reference for future studies on integrating Sargassum species into RAS and IMTA systems.

Integrated multitrophic aquaculture in ponds using substrate for periphyton as natural source of food

As a productive and sustainable alternative to fish farmers, the present study aims to evaluate the use of substrate for periphyton growth in an Integrated Multitrophic Aquaculture (IMTA) with complementary species. The studied species were: Nile tilapia (Oreochromis niloticus), grass carp (Ctenopharyngodon idella) and curimbatá (Prochilodus lineatus). The experiment had four treatments with three replicates that evaluated the IMTAs: [T100] Cb:C – tilapia inside hapas fed on recommended feed, with grass carp and curimbatás outside the hapas making use of natural food; [T50] Cb:C – the same species distribution with tilapia fed 50 % of the daily amount of commercial diet. Cb:C 100 and Cb:C 50 – grass carp and curimbatás fed on recommended feed at two feeding rates (100% and 50%) with substrate for periphyton growth in the feeding restriction treatment. In phase II, tilapias were included in all the treatments as a complementary species. Growth performance of fish and physical-chemical parameters of water were evaluated. In the proposed models, the species were efficient in utilizing the feed and in nutrient cycling, achieving productivity of 6 t/ha in the system without water renewal. Inserting secondary and complementary species reduced the feed conversion ratio (FCR) to values of 0.95 in systems under feed restriction and 1.28 in the groups that received 100% of commercial feed. Considering the reduction of the FCR and the high productivity, farmers can diversify their products in the same area without increasing inputs.

Integrated multitrophic aquaculture supply chain fish traceability with blockchain technology, valorisation of fish waste and plastic pollution reduction by seaweed bioplastic: A study in tuna fish aquaculture industry

The high demand for tuna, coupled with unsustainable supply chain practices, has triggered illegal fishing, overfishing, and environmental damage, including bycatch, pollution, and climate change impacts. To address these issues, the world urgently needs sustainable alternatives to meet tuna demand while preserving our oceans, marine species, and the environment. In this paper, a sustainable three-layer tuna fish supply chain model consisting of a single farmer, processor, and retailer is developed for two different quality levels of tuna fish. Green technology and integrated multi-trophic aquaculture (IMTA) methods are implemented at the farmer stage to reduce emissions and ocean pollution. Fish waste utilization technology, seaweed bioplastic packaging technology, and green technologies are implemented at the processor stage to reduce fish waste, plastic pollution, and carbon emissions. Blockchain technology is implemented for the traceability and transparency of the whole supply chain in order to avoid illegal and unsustainable tuna fish entering the market. The optimal solutions of the average integrated total profit are found by using the particle swarm optimization (PSO) algorithm in Python platform. The farmer's and processor's emission costs are reduced by 80% by investing in green technology. The transportation cost is also reduced. The fish waste utilization and plastic waste minimization costs of processors are reduced by more than 95% by investing in fish waste utilization and seaweed bioplastic packaging technology. The concavity of the average integrated total profit function is shown in a 3D graph. The optimal solution, sensitivity analysis, numerical examples, and managerial implications are presented for the tuna fish supply industries. The proposed model is applicable to any food processing industry.

Effects of Penaeus japonicus stocking density on water quality and bacterial community structure in water in an integrated multi-trophic aquaculture (IMTA) system

Effects of Penaeus japonicus stocking density on water quality and bacterial community structure in water in an integrated multi-trophic aquaculture (IMTA) system

Field assessment of the potential for small scale co-cultivation of seaweed and shellfish to regulate nutrients and plankton dynamics

The co-cultivation of seaweed alongside shellfish has the potential to regulate local dissolved nutrient concentrations and consequently affect plankton dynamics. Evidence for this has until now come largely from computational modelling and laboratory studies, rather than field studies. Here we report on weekly/bi-weekly profiling of inorganic nutrient concentrations (nitrate, nitrite, ammonium, phosphate, and silicate) over two years (2019–2020) at three sampling stations across a small-scale (16 ha) kelp and mussel farm in Porthallow Bay, Cornwall, UK. Nutrient concentrations were measured in conjunction with a range of related environmental variables, including water temperature, salinity, clarity, and phyto- and zoo- plankton abundance, biomass and community composition. These environmental data were also supplemented with river discharge data. Our results indicate typical seasonal variations in chemical (nutrient), physical (hydrographic), and biological (plankton) parameters across all three sampling stations and no significant reductions in inorganic nutrient concentrations in the water column downstream from the integrated kelp and shellfish farm. We conclude that the effectiveness of nutrient regulation by integrating seaweed and shellfish aquaculture will depend on local climatic and hydro-geochemical conditions (affecting background nutrient inputs), as well as the design and scale of integrated multi–trophic aquaculture (IMTA) systems.

Temporal force governs the microbial assembly associated with Ulva fasciata (Chlorophyta) from an integrated multi-trophic aquaculture system.

Ulva spp., one of the most important providers of marine ecosystem services, has gained substantial attention lately in both ecological and applicational aspects. It is known that macroalgae and their associated microbial community form an inseparable unit whose intimate relationship can affect the wellbeing of both. Different cultivation systems, such as integrated multi-trophic aquaculture (IMTA), are assumed to impact Ulva bacterial community significantly in terms of compositional guilds. However, in such a highly dynamic environment, it is crucial to determine how the community dynamics change over time. In the current study, we characterized the microbiota associated with Ulva fasciata grown as a biofilter in an IMTA system in the Gulf of Aqaba (Eilat, Israel) over a developmental period of 5 weeks. The Ulva-associated microbial community was identified using the 16S rRNA gene amplicon sequencing technique, and ecological indices were further analyzed. The Ulva-associated microbiome revealed a swift change in composition along the temporal succession, with clusters of distinct communities for each timepoint. Proteobacteria, Bacteroidetes, Planctomycetes, and Deinococcus-Thermus, the most abundant phyla that accounted for up to 95% of all the amplicon sequence variants (ASVs) found, appeared in all weeks. Further analyses highlighted microbial biomarkers representing each timepoint and their characteristics. Finally, the presence of highly abundant species in Ulva microbiota yet underestimated in previous research (such as phyla Deinococcus-Thermus, families Saprospiraceae, Thiohalorhabdaceae, and Pirellulaceae) suggests that more attention should be paid to the temporal succession of the assembly of microbes inhabiting macroalgae in aquaculture, in general, and IMTA, in particular. Characterizing bacterial communities associated with Ulva fasciata from an IMTA system provided a better understanding of their associated microbial dynamics and revealed this macroalgae's adaptation to such a habitat.

Microalgae Technology in Aquaculture Applications: A Comprehensive Literature Review

Microalgae are highly valuable across various industries due to their rich nutritional content and positive environmental impact. In the fast-growing field of aquaculture aimed at meeting global food needs, integrating microalgae technology can be highly beneficial. This literature review explores the diverse roles of microalgae in enhancing aquaculture, focusing on their nutritional benefits, water quality management, larviculture, Integrated Multi-Trophic Aquaculture (IMTA) systems, and bioremediation. Microalgae are excellent natural nutrient sources, offering high protein content, omega-3 fatty acids, vitamins, minerals, and antioxidants, vital for aquatic organism growth and health. Their contributions to water quality maintenance, larval stage nutrition, and waste nutrient uptake are critical. Additionally, microalgae play a pivotal role in IMTA by acting as primary producers and minimizing environmental impact. The review emphasizes challenges like economic constraints and strain optimization, underscoring the need for further research to fully leverage microalgae's potential in aquaculture, promising advancements to revolutionize the industry and enhance global food security.

Modeling particulate waste assimilation by blue mussels within the spatial constraints of a commercial fish farm: implications for multitrophic aquaculture

Commercial salmonid farming is typically performed in open-water net cages where interactions between the environment and production unit might be widespread and not easily predicted or controlled. Integrated multi-trophic aquaculture (IMTA) has been suggested to mitigate some of the environmental impacts. Based on empirical data, the assimilation of particulate waste from a commercial fish farm was modeled by two approaches to salmon/blue mussel IMTA: a system with mussels at the surface next to the fish farm and an alternative setup with mussels submerged under the farm. According to the model, 15% of the feed was defecated and assumed available to the mussels and the submerged mussel farm could assimilate 14.6% of the feces. Sensitivity analysis showed that the current speed, the mussel filtration rate, and the proportion of the material that settles slowly had an impact on this assimilation estimate, which could be significantly higher. However, the model did not include assimilation limitations due to particle size, which may contribute significantly to the submerged farm. The mussel farm at the surface mainly received small slow settling particles, and according to the model, only 0.4% of the fish farm waste was assimilated. The maximum obtainable assimilation was 5.5%. The fraction of slowly settling waste had the most pronounced influence on waste assimilation in the mussel farm at the surface. This is also among the most uncertain parameters, since the relative portion of different settling velocities of fish feces is highly variable, and more information on the size distribution of waste is needed.