Integrated Multi-trophic Aquaculture Research Articles

How much waste can the amphipod Gammarus insensibilis remove from aquaculture effluents? A first step toward IMTA

In recent years marine amphipods have been highlighted as an alternative live feed resource for Integrated Multi-Trophic Aquaculture (IMTA). Gammarus insensibilis Stock, 1966 is a native amphipod from the Mediterranean Sea and the north Atlantic Ocean and it is highly abundant in southern Spain marsh ponds. Its high potential for being intensively reared has been demonstrated in previous studies, as this species can feed on detritus and presents an interesting nutritional profile. In the present work, G. insensibilis specimens were maintained in closed batches at three different densities (100, 500 and 1000 ind L−1) and fed on dry or wet detritus (uneaten food and faeces from a fish RAS effluent) in order to assess for the first time the amount of wastes that they were able to remove. In parallel, a trial was performed to study the effect of dissolved inorganic nitrogen compounds (highly abundant in aquaculture effluents) on their survival, and the median lethal concentrations (LC50) in 96 h were calculated. Amphipods in all experiments and conditions showed promising survival rates higher than 80%. No advantages were observed when gammarids were maintained at high densities due to the significantly higher ammonium concentrations in these treatments, having an effect on intake but allowing sub-lethal conditions. Indeed, Gammarus insensibilis showed the highest tolerance for nitrate (1308 mg N-NO3− L−1), followed by nitrite (39.77 mg N-NO2− L−1) and ammonium (33.23 mg N-NH4+ L−1). Individuals at low densities removed significantly higher amounts of detritus, between 154.98 and 169.78 mg (dry weight detritus) per g (wet weight amphipods) and day. No differences were observed between removal rate of dry or wet detritus. Thus, authors recommend the use of wet detritus for a better handling and up-scaled trials in open or RAS systems equipped with a biofilter in order to avoid high ammonium concentrations impacting on intake.

Integrated Multi-Trophic Aquaculture (IMTA): Strategic model for sustainable mariculture in Samanco Bay, Peru

The development of industrial mariculture in Peruvian coasts will continue to grow according to global trends; however, it is characterized by being mostly monospecific, resulting in ecosystemic impacts due to organic matter, which deteriorate the benthic system and encourage eutrophication, negatively affecting biodiversity and fishery resources, which in a long term could turn the activity into an unsustainable practice. Therefore, it is imperative to adopt new production models, focused on the sustainability principle, such as Integrated Multi-Trophic Aquaculture (IMTA), that allow for greater efficiency, competitiveness, and profitability, while guaranteeing environmental balance. In this context, the present study has addressed the problem of Argopecten purpuratus cultivation in Samanco Bay, in which, based on a diagnosis of the bay's conditions, details of the cultivation, and a thorough analysis of the IMTA concept, a strategic model for mariculture is proposed in order to be adopted by private companies, after a validation process. These concepts can be transferred for their adaptation to other scenarios. Furthermore, it is expected that the academic sector, private companies, and the competent authority will be able to intervene synergistically in this process.

Integrated multitrophic aquaculture system applied to shrimp, tilapia, and seaweed (Ulva ohnoi) using biofloc technology

Integrated multitrophic aquaculture (IMTA) is a model that integrates organisms from different trophic levels, all sharing the same production system and, consequently, the nutrients. This study adopted shrimp (Penaeus vannamei) as the main species, tilapia (Oreochromis niloticus) as an organic consumer, and the seaweed (Ulva ohnoi) at different densities as an inorganic consumer in a biofloc production system. The study consisted of an experiment with three treatments and four replicates each: 1) No seaweed; 2) Seaweed 1 g L−1 (density of 1 g L−1 of U. ohnoi), and 3) Seaweed 2 g L−1 (density of 2 g L−1 of U. ohnoi). Shrimp (3.82 ± 0.05 g) were stocked in 800 L tanks at a density of 275 shrimp m−3, fish (14.44 ± 0.57 g) in 90 L tanks at a density of 267 tilapia m−3, and 50 and 100 g of seaweed stocked in 50 L tanks, corresponding to treatments with 1 and 2 g L−1, respectively. The integration of U. ohnoi at densities of 1 g L−1 and 2 g L−1 with P. vannamei and O. niloticus benefited the system through higher nitrogen (13,22 and 13,10% higher in the treatments 1 g L−1 and 2 g L−1 respectively) and phosphorus recovery (25,57 and 34% respectively) and an increase in total productivity (15,32 and 19,22% respectively), generating an ecological gain. Considering the similar final biomass of seaweed in a multitrophic system with shrimp and tilapia, the use of U. ohnoi at a density of 2 g L−1 is recommended since nutrient recovery by fish and shrimp was higher at this density.

Global greenhouse gas emissions from aquaculture: a bibliometric analysis

High greenhouse gas (GHG) emissions from aquaculture have contributed to global warming, arousing widespread concern worldwide. However, little is known about the historical evolution and future trends in research on GHG emissions from aquaculture. Here, we selected 553 papers on the GHG emissions from aquaculture from the Web of Science (WOS) Core Collection database to explore the knowledge base, research hotspots, and future development trends in this field by visually analyzing the number of publications, research power (countries, institutions, and authors), journal distribution, keyword co-occurrence, and reference co-citation. The results showed that the research field of GHG emissions from aquaculture has entered a rapid development stage (exponential function) since 2009, with Chinese research institutions and scholars playing a key role in this field. Research hotspots have shifted from inland freshwater aquaculture and monoculture to offshore aquaculture and ecological integrated aquaculture, respectively. Notably, an increasing number of studies have focused on the restoration of damaged coastal wetlands caused by land use and the enhancement of the blue carbon sink function to reduce GHG emissions. The findings of this work can provide scientific guidance for regulating GHG emissions from aquaculture and promoting the green and sustainable development of aquaculture.

The green seaweed, Enteromorpha intestinalis: An efficient inorganic extractive species for environmental remediation and improved performances of fed species in brackishwater integrated multi-trophic aquaculture (BIMTA) system

Seaweed has vast utilization benefits, in terms of food, cosmetics, fertilizers, and extraction of industrial gums and chemicals. Moreover, in integrated multi-trophic aquaculture (IMTA), seaweed can be utilized as an inorganic extractive species, but a very few studies were conducted so far involving the green seaweed, Enteromorpha sp. An experimental trial of 60 days was executed to ascertain the effect of varied stocking densities of Enteromorpha intestinalis on growth parameters, survival and physiological status of milkfish, Chanos chanos and the Pacific white-leg shrimp, Penaeus vannamei, and bioremediation effect in brackishwater IMTA (BIMTA) systems. There were three BIMTA systems with different biomass densities of seaweed, 0.5 (T1), 1.0 (T2), and 1.5 (T3) kg m−3 placed in 1000 L FRP tanks stocked with C. chanos (3.50 ± 0.01 g) at 25 number m−3 and P. vannamei (4.25 ± 0.04 g) at 50 number m−3 as fed species. The control (polyculture) had same number of milkfish and shrimp with no seaweed. Three treatments and control were maintained in triplicate. The fed species were provided with a polyculture feed containing 30% crude protein at 5% of the biomass daily. The results displayed that nitrogenous and phosphorus compounds were significantly lower (P < 0.05) in all three BIMTA treatments compared to the control. A better growth (P < 0.05) of C. chanos (12.52 ± 0.24 g) and P. vannamei (14.77 ± 0.35 g) was obtained in T3 and T2 BIMTA systems, respectively when compared with the control (milkfish: 11.01 ± 0.08 g, shrimp: 11.79 ± 0.58 g). Survival in shrimp was the highest in T3 treatment, but in milkfish, survival did not vary between different systems (P > 0.05). The blood (red blood cells, white blood cells and haemoglobin) and haemolymph (haemocyanin and total haemocyte count) parameters were better in fish and shrimp, respectively under BIMTA at harvest. Presence of seaweed provided a significant positive effect on the welfare parameter (glucose), whereas stress parameters (catalase, superoxide dismutase and cortisol) were comparatively low in fed species of BIMTA treatments than that of polyculture system. This trial suggested that T2 and T3 performed better among all and E. intestinalis can be an efficient inorganic extractive species for BIMTA at the optimum stocking density of 1.0–1.5 kg m−3.

Life history traits for Ophryotrocha craigsmithi (Wiklund, Glover &amp; Dahlgren, 2009), a candidate species in integrated multitrophic aquaculture

Ophryotrocha craigsmithi (Wiklund, Glover &amp;amp; Dahlgren, 2009) has repeatedly been observed in high densities at salmonid fish farms in Norway and has been shown to feed on the organic waste released during fish production. This species has therefore been pointed out as a candidate for the benthic component of integrated multitrophic aquaculture (IMTA). Little is known about the life history traits of Ophryotrocha species found at greater depths in temperate waters. Insight into life traits is of key importance in evaluating the bio-mitigation and harvest potential of (benthic) species within IMTA systems. In this study, we aimed to describe key life history traits for O. craigsmithi, such as growth, reproductive pattern, and offset of reproduction. The main findings are as follows: (I) O. craigsmithi exhibits early sexual maturation and rapid growth, going from 5 to 16 mm in length in 8 weeks; (II) their estimated lifetime is approximately 15 weeks with a generation time of 4 weeks; (III) there are strong indications that they are gonochoric semicontinuous spawners; (IV) the majority of mature eggs ranged from 120 to 150 µm; and (V) the larvae developed into a free-swimming stage after approximately 1 week. To this end, we present a framework for assessing the suitability of deposit-feeding polychaetes as candidate species in IMTA, considering environmental adaptiveness, production potential, as well as carbon and nitrogen mitigation capacity. On the basis of this, O. craigsmithi shows a high suitability as an extractive farmed species in benthic IMTA.

The future of intensive tilapia production and the circular bioeconomy without effluents: Biofloc technology, recirculation aquaculture systems, bio‐RAS, partitioned aquaculture systems and integrated multitrophic aquaculture

AbstractModern tilapia farming with low use of water aims, as in circular bioeconomy, to reduce inputs and fully reuse waste and effluents, closing flows or links of economic and ecological resources and decentralizing production systems (local production and local consumption). Concerns over diseases, market demand for a clean, sustainable and ecologically correct aquaculture, with greater and more efficient controls, increased predictability and repeatability of activities, are leading to a series of structural changes in the reuse of water and effluents through various closed recirculation systems with the reuse of waste as nutrients. In recent decades, one of the most important innovations and trends of tilapia culture is towards circular bioeconomy, characterized in this review by several recirculation systems, such as biofloc technology (BFT), recirculation aquaculture systems (RASs), bio‐RAS, partitioned aquaculture systems (PASs with split ponds, SPs; and in pond recirculation system, IPRS) and integrated multitrophic aquaculture (IMTA). The future of tilapia culture meshes with urban agriculture and waste fermentation, where low‐demand water recirculation systems will be the protagonists in the disruption of industries in five main sectors (materials, energy, information, transport and food/health), that still today focus on extraction, into a more sustainable local model.

Effects of Bellamya purificata Cultivation at Different Stocking Densities on the Dynamics and Assembly of Bacterial Communities in Sediment.

To optimize the integrated multi-trophic aquaculture (IMTA) model, improve the efficiency of resource utilization, and reduce environmental pollution, Bellamya purificata, as a potential bioremediation species, was studied to investigate the effect of B. purificata culture on the dynamics and assembly of bacterial communities in sediment. Four experimental groups were established at four different densities: 0, 234.38, 468.75, and 937.5 g/m2 (represented as CON, LD, MD, and HD, respectively). Each group was with three replicates. The 16S ribosomal RNA (rRNA) high-throughput sequencing was used to evaluate the composition, function, and assembly of bacterial communities in sediment. B. purificata cultivation significantly altered the composition and function of the bacterial communities in sediment; at high stocking density, it significantly decreased anaerobic and increased aerobic organic matter decomposition, whereas at low stocking density, it decreased the number of bacteria involved in sulfate reduction and inhibited the denitrification process. B. purificata decreased direct competition and promoted collaboration or niche sharing in bacterial communities, especially at the high stocking density. Moreover, B. purificata cultivation resulted in greater changes in the environmental factors. Variations in dissolved oxygen, pH, total nitrogen, nitrate, and nitrite levels were closely related to the altered composition and function of the bacterial communities. Stochastic processes dominated the bacterial community assembly in the sediment and B. purificata cultivation had limited impacts on the bacterial community assembly. The study provided a reference for the dynamics and assembly of bacterial communities in sediment with different densities of B. purificata cultivation and we hope that the findings will provide a theoretical reference for the optimization of IMTA and improve management strategies for B. purificata polyculture.

Evaluating sea cucumbers as extractive species for benthic bioremediation in mussel farms

Filter-feeding mussels blend suspended particles into faeces and pseudo-faeces enhancing organic matter flows between the water column and the bottom, and strengthening benthic-pelagic coupling. Inside operating farms, high bivalve densities in relatively confined areas result in an elevated rate of organic sinking to the seabed, which may cause a localized impact in the immediate surrounding. Deposit-feeding sea cucumbers are potentially optimal candidates to bioremediate mussel organic waste, due to their ability to process organic-enriched sediments impacted by aquaculture waste. However, although the feasibility of this polyculture has been investigated for a few Indo-Pacific species, little is known about Atlanto-Mediterranean species. Hence, for the first time, in the present study, we conducted a comparative investigation on the suitability of different Mediterranean sea cucumber species, to be reared in Integrated Multitrophic Aquaculture (IMTA) with mussels. A pilot-scale experiment was accomplished operating within a mussel farm where two sea cucumbers species, Holothuria tubulosa and Holothuria polii, were caged beneath the long-line mussel farm of Mytilus galloprovincialis. After four months, H. tubulosa showed high survivorship (94%) and positive somatic growth (6.07%); conversely H. polii showed negative growth (− 25.37%), although 92% of specimens survived. Furthermore, sea cucumber growth was size-dependent. In fact, smaller individuals, independently from the species, grew significantly faster than larger ones. These results evidenced a clear difference in the suitability of the two sea cucumber species for IMTA with M. galloprovincialis, probably due to their different trophic ecology (feeding specialization on different microhabitats, i.e. different sediment layers). Specifically, H. tubulosa seems to be an optimal candidate as extractive species both for polycultures production and waste bioremediation in M. galloprovincialis operating farms.

Food web in Mediterranean coastal integrated multi-trophic aquaculture ponds: Learnings from fatty acids and stable isotope tracers

Ecosystem responsible aquaculture practices are today imperative to feed the world increasing population. The culture of extractive species such as oyster with fed species such as fish is a promising solution to recycle waste streams, which would be otherwise lost and discharged into the surrounding environment. In Mediterranean earthen ponds, meagre (Argyrosomus regius), white seabream (Diplodus sargus) and grey mullet (Mugil cephalus) are three fish species of different trophic levels that are good candidates to be raised in integrated multi-trophic aquaculture (IMTA) pond with oysters (Magallana gigas) and macroalgae (Ulva flexuosa). Trophic links between species raised in IMTA ponds were inferred using the analysis of body fatty acid composition as well as in carbon and nitrogen stable isotopes. A combination of 3 treatments was tested: fish, oysters, phytoplankton and macroalgae (T1); fish, oysters and phytoplankton (T2); fish, phytoplankton and macroalgae (T3). Our results highlighted that the three fish species were in competition for food sources as they mainly fed on commercial feed whatever the treatment. However, grey mullet also consumed polychaetes that naturally grown in ponds. Macroalgae were not used by fish. In T1 and T2, oysters actively consumed the excess of phytoplankton. In T2, the absence of macroalgae reduce nutrient competition for phytoplankton growth and oysters have more available food. In earthen ponds, the production of fish with macroalgae or fish with oyster should be privileged compared to usual semi-intensive fish polyculture as the presence of extractive species reduced fish wastes.

Perspectives for Exploitation of Sabella spallanzanii’s Biomass as a New Integrated Multi-Trophic Aquaculture (IMTA) By-Product: Feeding Trial on Amphiprion ocellaris Using Sabella Meal

This paper is part of a series of studies aimed at understanding the potential exploitation of the biomass of the polychaete worm Sabella spallanzanii (Gmelin, 1791), which is obtained as a by-product of an innovative Integrated Multi-Trophic Aquaculture (IMTA) system. IMTA systems are designed according to an ecosystem approach with the aim to reduce marine monoculture impact while further increasing production via exploitation of valuable by-products. S. spallanzanii can remove large amounts of suspended matter by filtering large volumes of water per hour and performs well as an extractive organism under IMTA; however, it currently lacks any economic value, thus hindering its sustainable large-scale implementation. However, S. spallazanii has the potential to become competitive as a newcomer in fish bait, as an ornamental organism, and in fish feed markets. Notably, sabella meal has already been successfully tested as an attractant in an innovative fish feed. Here, we refer to the use of sabella meal as the main component (60%) in the formulation of a novel aquarium fish feed. Following the biochemical analysis of farmed sabella meal, the experimental feed was formulated by adding spirulina (25%) and dry garlic (15%) in such proportion as to be isoproteic and isoenergetic to the commercial control feed. After preliminary observations of the palatability of sabella meal for several tropical fish species, the novel experimental feed was tested on ocellaris clownfish, Amphiprion ocellaris (Cuvier, 1830), by evaluating their growth response in a 70-day feeding trial. The fish seemed to enjoy the experimental feed at least as much as the control, and both the control and treatment groups showed no significant differences in weight gain (p = 0.46), specific growth rate (p = 0.76), and feed conversion ratio (p = 0.48), reinforcing the suitability of S. spallanzanii as a viable source of animal proteins to be employed in the fish feed industry in a circular economy perspective.

Can IMTA provide added ecosystem value services in the fish farms of Greece?

In addition to food supply, there is a growing recognition of the wider ecosystem benefits of Integrated Multitrophic Aquaculture (IMTA) systems in coastal waters, including regulating services such as carbon sequestration and nutrient remediation. The water trophic status and the co-cultured species combinations affect IMTA productivity. In this study, we examined the ability of different combinations of IMTA organisms to remediate nutrients and the economic/environmental gain for reducing the environmental footprint in potential IMTA systems of the eastern Mediterranean. The results showed that the co-cultivation of organisms can reduce the negative effects on the marine environment of a fish farm both on the water column and the sediment. Meso- and eutrophic water states do not show a high variation in terms of foot print mitigation, with all three of the co-cultivated organisms to perform well. In oligotrophic waters, the obligatory absence of mussels reduces the effectiveness of the IMTA system. As expected, larger-sized IMTA systems have higher production rates and as a result higher percentage of nutrient removal. Finally, bivalve harvesting helps to remove the carbon that is trapped in their shells, contributing to the mitigation of processes related to climate change, such as the acidification of the oceans.

Sustainable production of biofuels and bioderivatives from aquaculture and marine waste

The annual global fish production reached a record 178 million tonnes in 2020, which continues to increase. Today, 49% of the total fish is harvested from aquaculture, which is forecasted to reach 60% of the total fish produced by 2030. Considering that the wastes of fishing industries represent up to 75% of the whole organisms, the fish industry is generating a large amount of waste which is being neglected in most parts of the world. This negligence can be traced to the ridicule of the value of this resource as well as the many difficulties related to its valorisation. In addition, the massive expansion of the aquaculture industry is generating significant environmental consequences, including chemical and biological pollution, disease outbreaks that increase the fish mortality rate, unsustainable feeds, competition for coastal space, and an increase in the macroalgal blooms due to anthropogenic stressors, leading to a negative socio-economic and environmental impact. The establishment of integrated multi-trophic aquaculture (IMTA) has received increasing attention due to the environmental benefits of using waste products and transforming them into valuable products. There is a need to integrate and implement new technologies able to valorise the waste generated from the fish and aquaculture industry making the aquaculture sector and the fish industry more sustainable through the development of a circular economy scheme. This review wants to provide an overview of several approaches to valorise marine waste (e.g., dead fish, algae waste from marine and aquaculture, fish waste), by their transformation into biofuels (biomethane, biohydrogen, biodiesel, green diesel, bioethanol, or biomethanol) and recovering biomolecules such as proteins (collagen, fish hydrolysate protein), polysaccharides (chitosan, chitin, carrageenan, ulvan, alginate, fucoidan, and laminarin) and biosurfactants.

Sponges as Emerging By-Product of Integrated Multitrophic Aquaculture (IMTA)

The use of marine sponges dates back thousands of years, and interest in these animals is increasing as new applications are discovered. Their potential is extensive, both in their ancient and still popular use as bath sponges for cosmetics and regarding the more recent discovery of bioactive secondary metabolites mainly of interest for the pharmaceutical industry and the less developed aquariology. Despite their proven biofiltration and ecosystem restoration ability and the biomass supply problem for the interested industries, few integrated multi-trophic aquaculture (IMTA) systems incorporate these invertebrates in their facilities. Therefore, in this brief review, the benefits that marine sponges could bring to rapidly growing IMTA systems are summarized, highlighting their suitability for a circular blue economy.

Comparative Study on the Structure of Plankton Community at Integrated Multi Trophic Aquaculture (IMTA) and Conventional Monoculture Net Cages at Coastal Area of Menjangan Besar, Karimunjawa Islands, Indonesia

Over the last decade, a modern sustainable aquaculture has become a driving force to speed up a production capacity but still pay attention to the carrying capacity of the environment for sustainability of the farming practice. We assessed the modern farming practice using stratified double net cage – Integrated Multi Trophic Aquaculture (SDNC-IMTA) to be compared to the conventional monoculture using structure of plankton community. The study was carried out at Menjangan Besar Island, Karimunjawa, Central Java during October 2021. The purpose of this study was to compare the plankton community's structure and determine the correlation between plankton abundance and water quality. Plankton sampling was carried out using the filtration method at three locations, i.e. monoculture cages, SDNC-IMTA cages, and reference sites. The abundance of phytoplankton and zooplankton were considerably higher at IMTA sites compared to the monoculture and reference sites. In particular, the highest abundance of zooplankton was found at the IMTA of 8569 ind.L-1, while the lowest abundance of zooplankton was found at the reference location of 3098 ind.L-1. The species considered as biological indicator were Ceratium sp., Dinophysis sp., Navicula sp., Pseudonitzchia sp., Oscillatoria sp., and Rhizolenia sp. The results of the NMDS ordination of phytoplankton data obtained a tendency of grouping the stations based on the three main sampling sites, while results from the zooplankton data did not show clustering between the sampling sites. The analysis of plankton abundance using with BIO ENV (Primary V 6.1.5) showed that the most abiotic factors affecting the abundance of plankton were temperature, turbidity, and salinity ( pvalue = 0.176).

Blockchain Traceability in Trading Biomasses Obtained with an Integrated Multi-Trophic Aquaculture

This study explores the application and critical issues related to the implementation of blockchain technology (BT) to the aquaculture sector, in order to understand the possibilities of improving the relationship with the supply chain and the end consumer, with a view to a sustainability for the marine environment and circular economy. Starting from considerations of commercial and political challenges related to credibility and fairness for all parties involved—from producers, to retailers, to end consumers—the procedure adopted was applied to the case of an Integrated Multi-Trophic Aquaculture project, developed in the sea of Taranto (Italy). Furthermore, it considered two different end markets: the food market for farmed fish and the ornamental fish market for marine aquariums. The results of the study confirm that although the implementation of BT by industries and producers of marine species has the potential to lead to successful sustainability solutions, such adoption is feasible over time only if all actors in the supply chain, from aquaculture companies, to retailers, to consumers, are actively and consciously involved and can access common benefits.

Potential of innovative marine aquaculture techniques to close nutrient cycles

AbstractAquaculture is an established technique for producing marine species. However, it creates large amounts of nutrient‐rich waste. Therefore, it is worth examining the methods available to use these nutrients and close the nutrient cycle. This review covers research activities of different saline water methods for food production. These are Integrated Multi‐Trophic Aquaculture (IMTA), Biofloc Technology (BFT) and marine aquaponics. IMTA combines on‐ and offshore aquaculture with macroalgae and filter feeder production. Commercial implementations have been achieved but are not widely used. Especially shrimp are suitable for cultivation in saline BFT systems. Few commercial deployments exist. There is a well‐established market for the products of IMTA and BFT systems. Marine aquaponics is increasingly being tested as part of an expansion of Recirculating Aquaculture Systems (RAS) and BFT systems, but commercial implementations are not known. Moreover, there is no established market for the resulting salt‐tolerant plants (halophytes). Market prices and popularity were evaluated to assess the economic potential of the different plant and aquaculture species farmed with IMTA, BFT and marine aquaponics. There are established markets for well‐known products, but therefore the competition is greater. Niche products are offered occasionally, but often achieve top prices. Closing nutrient cycles and increasing saline water usage for food production as well as high product diversity are necessary to mitigate the increasing pressure on freshwater resources and to be able to feed the growing world population. Therefore, IMTA, BFT and marine aquaponics are promising techniques for reducing pressure on freshwater resources and improving food supply.

A Comparative Approach to Detect Macrobenthic Response to the Conversion of an Inshore Mariculture Plant into an IMTA System in the Mar Grande of Taranto (Mediterranean Sea, Italy)

The expected bioremediation effect, driven by the conversion of an inshore mariculture plant into an Integrated Multi-Trophic Aquaculture (IMTA) system, which could mitigate the fish farm impact, related to the accumulation of organic matter on the seabed, has been studied. The ecological quality status was studied following a Before-After-Control-Impact (BACI) design and variation measured through M-AMBI and compared with the results of univariate and multivariate analyses of variance, to evaluate the sensitivity of the two methodologies. Results from M-AMBI indicated a sharp change in the ecological quality status, just after one year of the conversion of the plant. By contrast, although changes were detected also utilizing univariate and multivariate statistical analysis, the natural temporal variability characterizing the area partially masked evidence of environmental amelioration.

Development of integrated multitrophic aquaculture–based cage rearing system in an underutilized fishing port and its application in marine stock enhancement

Human activity and global climate change have severely affected marine ecosystems and fishery resources. Habitat conservation and stock enhancement are considered effective methods. Moreover, with the gradual disappearance of fishery resources, fishing ports have become underutilized spaces. Currently, 73 of the 221 fishing ports in Taiwan are underutilized. Therefore, we, for the first time, developed an integrated multitrophic aquaculture (IMTA)-based cage rearing system suitable for stock enhancement and applied it in an optimal underutilized fishing port after the site evaluation and selection of 17 potential fishing ports fishing. We further tested that hypothesis that hatchery-produced organisms can be reared and monitored appropriately in this cage rearing system with good survival and growth as well as less environmental impact and handling stress. Through the collocation of various release organisms of different trophic levels, the cage rearing system can reduce environmental impacts as evidenced by the steady water quality (stable pH and undetectable levels of ammonia nitrogen, nitrates, and nitrites). As for the fish welfare, this semiartificial rearing system could also reduce the discomforts of hatchery-produced organisms after transportation and facilitate their adaptations to the released environments as evidenced by positive growth and high survival rates (94%–98%). The cultured and naturally grown shellfish and algae on the cage nets could provide habitats for hatchery-produced and wild organisms that facilitate habitat conservation and stock enhancement. Taken together, we have demonstrated that it is feasible to implement this novel IMTA-based cage rearing system in an underutilized fishing port required for marine stock enhancement.

Short-term nutrient removal efficiency and photosynthetic performance of Ulva pseudorotundata (Chlorophyta): potential use for Integrated Multi-Trophic Aquaculture (IMTA)

Short-term nutrient removal efficiency and photosynthetic performance of Ulva pseudorotundata (Chlorophyta): potential use for Integrated Multi-Trophic Aquaculture (IMTA)