Integrated multi-trophic aquaculture involves cultivating fed species with extractive species that utilize wastes from aquaculture for their growth. All components have commercial value, as well as roles in biomitigating. The IMTA concept should also be understood within an integrated land/coastal aquaculture ecosystem approach. Regulatory frameworks and financial incentives may be required to fully realize the benefits of IMTA systems. Differentiation of IMTA products through traceability and ecolabeling will be key in their promotion.
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Integrated multi-trophic aquaculture involves cultivating fed species with extractive species that utilize the inorganic and organic wastes from aquaculture for their growth. The mix of organisms of different trophic levels mimics the functioning of natural ecosystems. All the cultivation components have commercial value, as well as key roles in recycling processes and biomitigating services. Some of the externalities of fed monoculture are internalized, increasing the overall sustainability and long-term profitability of aquaculture farms.
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In integrated multi-trophic aquaculture, farmers combine the cultivation of fed species such as finfish or shrimp with extractive seaweeds, aquatic plants and shellfish and other invertebrates that recapture organic and inorganic particulate nutrients for their growth. Such systems take advantage of synergistic interactions among species while biomitigation takes place for greater environmental and economic stability, as well as societal acceptability. Culture organisms must be chosen based on their complementary functions in the ecosystem, as well as economic potential.
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Reducing negative environmental impacts from aquaculture activities is a key issue for ensuring long-term sustainability of the industry. This study examines the major findings and methodology aspects from 28 peer-reviewed studies on marine aquaculture systems integrating fed and extractive organisms. All studies include seaweeds as extractive organisms. The main objective was to analyse the degree of relevance these findings have for large-scale implementation of integrated mariculture practices, and to identify necessary research areas for a future research agenda.The following directions for future research were identified: (1) understand in detail the important biological/biochemical processes in closed recirculating and open seaweed culture systems; (2) conduct research into these advanced aquaculture technologies at scales relevant to commercial implementation or suitable for extrapolation; (3) broaden the focus to include factors affecting seaweed growth and uptake capacity; (4) improve experimental design for statistical calculations; (5) attain a detailed understanding of the temporal variability in seaweed-filtered mariculture systems; (6) define numerical design parameters critical for engineers in designing commercial recirculation systems with seaweed filters; (7) study the influences of location-specific parameters, such as latitude, climate and local seaweed strains/species, on seaweed filter performance; (8) include economic components, considering the added value of seaweeds, and feasibility aspects; (9) analyse the role and function of integrated aquaculture practices for improved environmental, economic, and social acceptability within the broader perspective of integrated coastal management initiatives; and (10) develop educational, training and financial incentive approaches to transfer these novel and somewhat complex technologies of integrated mariculture from the scientists to the industry.
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While the concept and practice of integrated aquaculture is well-known in inland environments particularly in Asia, in the marine environment, it has been much less reported. However, in recent years the idea of integrated aquaculture has been often considered a mitigation approach against the excess nutrients/organic matter generated by intensive aquaculture activities particularly in marine waters. In this context, integrated multitrophic aquaculture (IMTA) has emerged, where multitrophic refers to the explicit incorporation of species from different trophic positions or nutritional levels in the same system. Integrated marine aquaculture can cover a diverse range of co-culture/ farming practices, including IMTA, and even more specialized forms of integration such as mangrove planting with aquaculture, called aquasilviculture. Integrated mariculture has many benefits, among wich bioremediation is one of the most relevant, and yet is not valued in its real social and economic potential although the present document provides some initial economic estimates for the integration benefits derived from bioremediation. Reducing risks is also an advantage and profitable aspect of farming multiple species in marine environments (as in freshwaters): a diversified product portfolio increases the resilience of the operation, for instance when facing changing prices for one of the farmed species or the accidental catastrophic destruction of a crop. Yet such perspectives are far from been considered in mariculture where, on the contrary, there is a tendency to monoculture.
Modern integrated mariculture systems must be developed in order to assist sustainable expansion of the sector in coastal and marine ecosystems thus responding to the global increase for seafood demand but with a new paradigm of more efficient food production systems. Successful integrated mariculture operations must consider all relevant stakeholders into its development plan government, industry, academia, the general public and non-governmental organizations must work together and the role of integrated mariculture within integrated coastal zone management plans must be clearly defined.
There is a need to facilitate commercialization and promote effective legislation for the support and inclusion of integrated mariculture through adequate incentives particularly considering the reduction of environmental costs associated to monoculture farming. Bioremediation of fed aquaculture impacts through integrated aquaculture is a core benefit but the increase of production, more diverse and secure business, and larger profits should not be underestimated as additional advantages.
In many cases, more research is needed to further integrated mariculture – particularly regarding the technical implementation of a farm. At this level, an important issue is to adopt adequate management practices that avoid or reduce the likelihood of disease transmission within and between aquaculture facilities or to the natural aquatic fauna. Also, careful consideration should be paid to the selection of species used in polyculture or integrated multitrophic aquaculture to reduce potential stress and suffering of culture individuals. Integrated aquaculture should be looked upon as a very important tool to facilitate the growth of marine aquaculture and promote sustainable development
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Coastal aquaculture involves the cultivation of marine and brackish water species in ponds, protected Bays, Gulfs and Lagoons. Aquaculture became an important commercial food production since 1960s (Chua, 1986; 1994) and lateer in 1970s the aquaculture transformed rapidly with the success in breeding work of fish, shellfish, seaweed, artificial feed and genetic improvements. In particular Shrimp farming spread far and wide within three decades and became the prime export earning industry in many parts of the World (Liao, 1990). In the last two decades, many intensive aquaculture enterprises have suffered severe losses due to disease outbreaks (ADB and NACA, 1991) due to poor farm management. The quality of aquatic environment began to show a sign of unsustainability in many countries. U$ 1 billion dollar has been lost due to shrimp disease in Asia (FAO and NACA, 1995).
It was reported in many countries like Taiwan, Thailand, Philippines, China and India. The environmental impact of aquaculture is becoming a matter of concern in the present scenario due to increase in industrialization, intensified aquaculture development, urbanization, population increase, pollution of coastal water due to sewage-industrial and agricultural waste. Intensification of culture practices has led to environmental deterioration both within the system and in the surrounding areas. The code of conduct for Responsible Fisheries evolved by the Food and Agricultural Organization, Rome in 1995 (FAO, 1995) is adapted by 168 countries including India. India is a signatory to implement many aspects besides the major issues related to aquaculture i.e. assessment for the discharge of effluents, use of drug and chemicals during aquaculture activities. Sustainability has become the major challenge to aquaculture development.
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Derivation of biofuel from microalgae biomass has been widely researched in the past few decades. Microalgae is capable of producing 58,700 litres oil per hectare that can generate 121,104 litres biodiesel per hectare, which seemingly a promising transition over conventional fossil fuels. Nevertheless, economic sustainability of com- mercial scale production of microalgae biomass is still in shadows of doubt, especially the cultivation and harvesting process. Apparently, the microalgae cultivation system has evolved from traditional open pond to various modern photobioreactor (PBR) designs. However, with regards to tubular and flat panel PBRs as the most ubiquitous systems for biofuel production at commercial level, extensive discussion on reactor config- urations and design betterment was presented in this review, along with precise technical comparison on cost and energy requirements for the cultivation systems. This review intended to serve as guideline for long term adoption of these well-established cultivation technologies in biofuel plants given the numerous economic benefits. Besides that, in attempt to lower the harvesting cost, potential use of various waste biomass as bio- flocculants to recover microalgae biomass was introduced in this review. This article also deliberates direction on potential policy interventions to produce microalgae biofuel in a more sustainable and cost-effective manners in near future.
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The aim of this work was to evaluate the potential of ultrasound (US), alone or in combination with mild heating and/or EDTA towards reduction of As, Cd, I, and Hg content of Laminaria hyperborea. Concentrations of As, Cd, I, and Hg of 56.29, 0.596, 7340, and <0.01 mg kg−1 of dry weight, respectively, were found in L. hyperborea blades. Treatment with US at 50 ◦C increased approx. 2-fold the amount of As released, although did not affect significantly the content of Cd or I, as compared to control (no US) samples. Reducing the temperature to 8 ◦C significantly decreased the effect of US, but heating at 80 ◦C did not cause a significant effect as compared to treatments at 50 ◦C. On the other hand, treatment with 0.1 N EDTA at 50 ◦C enhanced the percentage of Cd released by approximately 7-fold, regardless of sonication. In the present work, the combination of US and EDTA at 50 ◦C for 5 min led to a significant reduction of the As (32%), Cd (52%) and I (31%) content in L. hyperborea, thus improving the product’s safety for consumers.
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Obtaining eggs and larvae in large quantities is a critical point for the economic viability of sea cucumber aquaculture. In this paper, spawning induction methods and in-vitro fertilisation (IVF) methods are presented and compared. The IVF technique developed in Madagascar (MH-IVF) is a simple, cost-efficient method that enables hatcheries to obtain clean, fertilised eggs of sea cucumbers year-round. MH-IVF does not require high-tech equipment and is applicable in small- and large-scale hatcheries. It ensures the best control at the very beginning of the work on the number and type of genitors (i.e. sex, length, weight, colour); the quality of the gonads (healthy versus parasitised); and the number, size and quality of spermatozoa and eggs. MH-IVF involves the sacrifice of very few genitors compared with the individuals obtained and sacrificed for production. Yet, it does not influence genetic drift any more than spawning induction methods.
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The cultivation of seaweeds contributes significantly to the national economy and provides employment to the economically backward communities of Sabah, Malaysia. Cultivation of seaweeds on a commercial scale requires a large number of propagules with desirable phenotypic traits which include high growth rates and resistance to diseases. Thus, seaweed tissue culture can be considered as one of the best methods to provide a large amount of seedlings for commercial cultivation. The parameters which have been determined to have a significant effect on the growth of in vitro propagated Eucheuma seaweeds are the sterilization techniques, media composition, light intensity and aeration. Eucheuma seaweeds were surface sterilized by washing with optimized concentration of disinfectants and antibiotics. The appropriate medium was determined to be Provasoli’s Enriched Seawater (PES) while optimum light intensity was in the range of 6,000 lux. Continuous aeration was important to provide enough carbon dioxide for carbon fixation. Hormone IAA:BAP was provided with concentration ratio of 5:1 mg/l. Temperature was maintained in the range of 25 to 30°C while salinity of the seawater was kept constant at 32 ppt.
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