![Integrated Multi-Trophic Aquaculture: A Laboratory and Hands-on
Experimental Activity to Promote Environmental Sustainability
Awareness and Value of Aquaculture Products
(Ref:Marta Correia etal.2020)
• intensive aquaculture production still releases high amounts of nutrients and organic wastes into the environment
that can cause eutrophication of coastal areas and other aquatic systems (Sarà et al., 2018a).
• This is because only about 20–40% of the nitrogen (Oliva-Teles et al., 2020) and less than 50% of the energy
intake (Bureau et al., 2002; Peres and Oliva-Teles, 2005) are retained by the species produced.
• The recognition of the significant environmental and social impact of intensive production increased the interest
in alternative sustainable practices, such as integrated multi-trophic aquaculture (IMTA) (Alexander et al.,
2016a; Sarà et al., 2018b).
• Integrated multi-trophic aquaculture aims at the integrated production of aquaculture species of different trophic
levels under a circular economy approach, minimizing energy losses and environmental deterioration (Food and
Agriculture Organization [FAO], 2009; Chopin et al., 2012; Hughes and Black, 2016; Buck et al., 2018). Under
IMTA production, the uneaten feed and wastes of one species are recaptured and converted into feed, fertilizers,
and energy to another species.
• IMTA can promote aquaculture sustainability, with environmental, economic, and social advantages. This can be
achieved through nutrient cycling, increased economic resilience arising from increased production efficiency,
product diversification, and potential price premiums (Chopin et al., 2012; Van Osch et al., 2019).
• There are multiple configurations of IMTA systems, integrating the production of vertebrate and invertebrate
species and macroalgae. Cultivated organisms are fed aquatic species, like fish or shrimp, and species extracting
the organic and inorganic matter from the water.
• Species extracting the organic matter may be mussels, oysters, clams, sea urchins or polychetes. These species
feed on organic waste, such as uneaten food and feces. Species extracting the inorganic matter, such as
macroalgae (e.g., species of the genera Ulva, Gracilaria, Saccharina, Laminaria), capture and use the inorganic
nutrient wastes.](https://image.slidesharecdn.com/integratedmulti-trophicaquacultureimtaitsapplicationsbyb-230729175528-2abb6def/85/Integrated-Multi-Trophic-Aquaculture-IMTA-its-applications-by-B-pptx-9-320.jpg)
Integrated Multi-Trophic Aquaculture(IMTA) its applications by B.pptx
- 1. Integrated Multi-Trophic Aquaculture(IMTA) its potential application in Promoting Environmental Sustainability and Value of Aquaculture Products By: Bhukya Bhaskar Fisheries
- 2. Introduction • Concept of Integrated multi-trophic aquaculture (IMTA) Integrated aquaculture systems as detailed in Neori et al., (2004) Barrington et al. (2009) and Angel and Freeman (2009) and case studies in India are briefly given below. • In many monoculture farming systems the fed-aquaculture species and the organic/ inorganic extractive aquaculture species (bivalves, herbivorous fishes and aquatic plants) are independently farmed in different geographical locations, resulting in pronounced shift in the environmental processes. • Integrated multi-trophic aquaculture (IMTA) involves cultivating fed species with extractive species that utilize the inorganic and organic wastes from aquaculture for their growth. • According to Barrington (2009), IMTA is the practice which combines, in the appropriate proportions, the cultivation of fed aquaculture species (e.g. finfish/shrimp) with organic extractive aquaculture species (e.g. shellfish/herbivorous fish) and inorganic extractive aquaculture species (e.g. seaweed) to create balanced systems for environmental sustainability (biomitigation) economic stability (product diversification and risk reduction) and social acceptability (better management practices). • This farming method is different from finfish “polyculture”, where the fishes share the same biological and chemical processes which could potentially lead to shift in ecosystem. • Multi-trophic refers to the combination of species from different trophic levels in the same system. • The multi-trophic sub-systems are integrated in IMTA that refers to the more intensive cultivation of the different species in proximity of each other, linked by nutrient and energy transfer through water.
- 3. Selection of species • Market demand for the species and pricing as raw material or for their derived products • Complementary roles with other species in the system • Adaptability in relation to the habitat • Culture technologies and site environmental conditions • Ability to provide both efficient and continuous bio- mitigation • Commercialization potential • Contribution to improved environmental performance. • Compatibility with a variety of social and political issues.
- 4. • Inorganic extractive sub-system in IMTA Bio-filtration by aquatic plants, is assimilative, and therefore adds to the assimilative capacity of the environment for nutrients. • With solar energy and the excess nutrients (particularly C, N and P), plants photosynthesize new biomass. • The operation recreates in the culture system a mini-ecosystem, wherein, if properly balanced, plant autotrophy counters fish and microbial heterotrophy, not only with respect to nutrients but also with respect to oxygen, pH and CO2 . • Plant bio-filters can thus, in one step, greatly reduce the overall environmental impact of fish culture and stabilize the culture environment. • Furthermore, farming of species that are low in food chain and that extract their nourishment from the water involves relatively low input. • Seaweeds are most suitable for bio-filtration because they probably have the highest productivity of all plants and can be economically cultured. • Seaweeds have a large market for human consumption as phycocolloids, feed supplements, agrichemicals, nutraceuticals and pharmaceuticals. • Seaweed farming has long been promoted in China in areas of marine cage culture for bio-extraction of nutrients in the seawater. • FAO aquaculture statistics record 37 separate seaweed species groups with dominance of Eucheuma seaweeds (8.44 million tonnes) Kappaphycus alvarezii and Eucheuma spp. farmed in tropical and subtropical seawater followed by Japanese kelp (5.94 million tonnes).
- 5. Cont… • The choice of seaweed species for inclusion in an integrated aquaculture system must first depend upon meeting a number of basic criteria such as high growth rate and tissue nitrogen concentration; ease of cultivation and control of life cycle; resistance to epiphytes and disease-causing organisms; and a match between the ecophysiological characteristics and the growth environment. • In addition, given the ecological damage that may result from the introduction of non-native organisms, the seaweed should be a local species. • Beyond these basic criteria, the choice of seaweed will be influenced by the intended application. • If, the focus is placed on the value of the biomass produced, then subsequent decisions will be based on the quality of the tissue and added value secondary compounds. • If the principal focus is the process of bioremediation, then nutrient uptake and storage and growth are the primary determinants. • The optimal system would include a seaweed species that incorporates both value and bioremediation. • Among seaweeds, the ‘thin sheet’ morphology has a higher growth rate than the fleshy seaweeds. It is more difficult to generalize on nutrient sequestration. • A bio-filter seaweed species must grow very well in high nutrient concentrations, especially ammonium. Seaweed that does not show this capacity has only a limited use. • To take up nitrogen at a high rate, fast-growing seaweed should be able to build up a large biomass N content. • The common bio-filter seaweeds, when grown in eutrophic waters, accumulate a high total internal N content. • When expressed on a percent dry weight basis, maximal values for Ulva, Gracilaria and Porphyra grown in the eutrophic conditions characteristic of fish farm effluent range between 5–7% as N in dry weight (dw) or 30– 45% as protein in dw. • In addition to the requisites described above, the ideal choice for the seaweed biofilter also has a market value. • This encompasses the sale of seaweed products for a range of markets, including human consumption as food or therapeutants, specialty biochemicals, or simply as feed for the algivore component of the integrated system.
- 6. Organic extractive species sub-system in IMTA • In a conceptual open-water integrated culture system, filter-feeding bivalves are cultured adjacent to meshed fish cages, reducing nutrient loadings by filtering and assimilating particulate wastes (fish feed and faeces) as well as any phytoplankton production stimulated by introduced dissolved nutrient wastes. • Waste nutrients, rather than being lost to the local environment, as in traditional monoculture, are removed upon harvest of the cultured bivalves. • With an enhanced food supply within a fish farm, there is also potential for enhancing bivalve growth and production beyond that normally expected in local waters. • Therefore, integrated culture has the potential to increase the efficiency and productivity of a fish farm while reducing waste loadings and environmental impacts. • How filter-feeders interact with the environment, their uptake rate, and other aspects are available in the literature. A native bivalve species must be consider to suit the local ecology, potential markets, and the need to engineer IMTA systems to accommodate them. • Literature shows that 95% of particles released from aquaculture systems, fish farms, and closed recirculation systems are ~20 microns diameter (5-200 micron range), and that they will settle. There is evidence that filter- feeders are selective in extracting particles from the water column, rejecting the rest. • Thus, it is important to know the particle size of wastes from an IMTA system and to choose from among the wide range of bivalves that will select the required particle size and type. • Marketability of these secondary products is a factor, but it need not be an overriding consideration. • You could add a fish range alongside your primary fed fish to act as a first-stage bio-filter and use a marine bivalve as the second stage. • An example of an ecosystem-based IMTA model was built as a Peace Corps-style project in Malaysia in the 1990s to remove contaminants from shrimp farm waste water, otherwise normally released into local waters. • The project found that 72% of the nitrogen and 61% of the phosphorus could be removed, mostly as harvested shellfish product using a simple, engineered system. Studies have shown that bivalves are capable of utilising fish farm wastes as an additional food supply. • However, few practical studies have been undertaken, with conflicting conclusions regarding the potential for open-water integrated culture to enhance bivalve production and, by implication, to significantly reduce fish farmwastes. The bivalve mussel, Perna viridis and oyster Crassostrea madrasensis that are com
- 7. Integrated multi-trophic aquaculture (Ref: Thierry Chopin et al.2010) • Integrated multi-trophic aquaculture (IMTA) has the potential to play a role in reaching these objectives by cultivating fed species (e.g., finfish fed sustainable commercial diets) with extractive species, which utilize the inorganic (e.g., seaweeds) and organic (e.g., suspension and deposit feeders) excess nutrients from aquaculture for their growth. • The IMTA concept is extremely flexible. • To use a musical analogy, IMTA is the central/overarching theme on which many variations can be developed according to the prevailing environmental, biological, physical, chemical, societal and economic conditions where the IMTA systems are operating. • It can be applied to open-water or land-based systems, and marine or freshwater systems (sometimes called “aquaponics” or “partitioned aquaculture”). • Integration should be understood as cultivation in proximity, not considering absolute distances but connectivity in terms of ecosystemic functionalities. • The IMTA concept can be extended within very large ecosystems. Biomitigation value • A few economic analyses have indicated that the outlook for increased profitability through IMTA is promising. However, these analyses were based solely on the commercial values of harvested biomass and used conservative price estimates for the co-cultivated organisms based on known applications. One aspect not factored into these analyses was the fact that the extractive component of an IMTA system not only produces a valuable multi-purpose biomass, but also simultaneously renders waste reduction services to society. • It is particularly important to recognize that once nutrients have entered coastal ecosystems, not many removal options are available. The use of extractive species is one of the few realistic and cost-effective options. The economic values of the environmental services of extractive species should, therefore, be counted in the evaluation of IMTA components. Nutrient trading credits • To improve the sustainability of anthropogenic nutrient-loading practices such as aquaculture, incentives such as nutrient trading credits (NTCs) should be established as a means to promote nutrient load reduction or nutrient recovery. During the last few years, there has been much talk about carbon credits. However, within coastal settings, the concerns have largely been with nitrogen, due to the fact that its typical role as a limiting nutrient is no longer the case in some regions. • The potential effects of carbon loading in the marine environment should also be considered. Localized benthic anoxia and, consequently, hydrogen sulfide release can occur when solid waste deposition rates exceed aerobic decomposition rates. Ocean acidification due to increased dissolved carbon dioxide levels has also prompted serious new concerns. • With an appropriate composition of co-cultured species, IMTA has the potential to reduce the amounts of dissolved inorganic and solid organic forms of nitrogen, carbon and phosphorus, making extractive aquaculture a good candidate for NTCs or another suitable approach to deal with the pressing issues of coastal nutrient loading. • Interestingly, the removal of nitrogen could be about 100 times more lucrative than that of carbon. The cost of removing nitrogen is not clearly defined, but studies may help define a range of possible prices for economic evaluation of the NTC concept. The cost of removing 1 kg of nitrogen varies between U.S. $3 and $38 at sewage treatment facilities, depending on the technology used and the labor costs in different countries. The municipality of Lysekil in Sweden is paying approximately $10/kg removed by the filter-feeding mussel, Mytilus edulis, to the farm Nordic Shell Produktion A.B.
- 9. Integrated Multi-Trophic Aquaculture: A Laboratory and Hands-on Experimental Activity to Promote Environmental Sustainability Awareness and Value of Aquaculture Products (Ref:Marta Correia etal.2020) • intensive aquaculture production still releases high amounts of nutrients and organic wastes into the environment that can cause eutrophication of coastal areas and other aquatic systems (Sarà et al., 2018a). • This is because only about 20–40% of the nitrogen (Oliva-Teles et al., 2020) and less than 50% of the energy intake (Bureau et al., 2002; Peres and Oliva-Teles, 2005) are retained by the species produced. • The recognition of the significant environmental and social impact of intensive production increased the interest in alternative sustainable practices, such as integrated multi-trophic aquaculture (IMTA) (Alexander et al., 2016a; Sarà et al., 2018b). • Integrated multi-trophic aquaculture aims at the integrated production of aquaculture species of different trophic levels under a circular economy approach, minimizing energy losses and environmental deterioration (Food and Agriculture Organization [FAO], 2009; Chopin et al., 2012; Hughes and Black, 2016; Buck et al., 2018). Under IMTA production, the uneaten feed and wastes of one species are recaptured and converted into feed, fertilizers, and energy to another species. • IMTA can promote aquaculture sustainability, with environmental, economic, and social advantages. This can be achieved through nutrient cycling, increased economic resilience arising from increased production efficiency, product diversification, and potential price premiums (Chopin et al., 2012; Van Osch et al., 2019). • There are multiple configurations of IMTA systems, integrating the production of vertebrate and invertebrate species and macroalgae. Cultivated organisms are fed aquatic species, like fish or shrimp, and species extracting the organic and inorganic matter from the water. • Species extracting the organic matter may be mussels, oysters, clams, sea urchins or polychetes. These species feed on organic waste, such as uneaten food and feces. Species extracting the inorganic matter, such as macroalgae (e.g., species of the genera Ulva, Gracilaria, Saccharina, Laminaria), capture and use the inorganic nutrient wastes.
- 10. Cont… • IMTA allows the creation of more sustainable production systems because wastes of fish/shrimp production are valued as a resource rather than considered a burden or pollution. • This contributes to environmental sustainability and a more efficient use of resources, while favoring economic diversification (product diversification, bringing company stability through risk reduction), and social acceptability (best management practices). • Integrated multi-trophic aquaculture has additionally been recognized as a contributor to reducing public opposition toward intensive aquaculture (Ridler et al., 2007; Alexander et al., 2016b; Buck et al., 2018). • Nevertheless, there is still a pressing need to enhance societal awareness, perception, and acceptability of aquaculture products, and disseminate sound and rigorous information to consumers about the aquaculture industry and its environmental sustainability. • Activities fostering understanding about sustainable aquaculture practices, the benefits of its products to consumers, and how they meet end-users needs are also required to implement steady consumption of aquaculture products. • The IMTA concept, and its advantages over the conventional methods, provides an excellent opportunity to teach students, and inform the general public, about environmental sustainability, increase their ocean literacy, as well as improve social acceptance of aquaculture products, enhancing its consumption (Shuve et al., 2009).
- 11. Experimental IMTA (Ref:Marta Correia etal.2020) • Two IMTA units were implemented at laboratorial scale (210 L) in the Marine Zoological Station of Porto University. • Each of these two indoor systems comprised four tanks, including one for European seabass (Dicentrarchus labrax) as marine carnivorous fish, one for sea urchin (Paracentrotus lividus), a grazing invertebrate, and one for a seaweed (Ulva sp.). • This was a closed system with recirculation, in which each tank was supplied by a continuous flow of seawater from the previous thank (the direction of the flow was: fish, sea urchin, seaweed and back to the fish unit). • The fish tank was built with the incorporation of a particulate organic matter trap. • The trap prevented the sedimentation of organic particles (feces and surplus feed) in the fish tank and ensured their continuous transference to the sea urchin tank. • The trial lasted for 70 days. During this period, the water temperature was regulated to 18.0 ± 0.5°C, salinity averaged 34 ± 1‰, and dissolved oxygen averaged 95% of saturation. • Photoperiod was adjusted to 12/12 h light/dark cycles. In both systems, the initial stocking density of fish, sea urchin, and Ulva lactuca were 6.9, 19.5, and 1.9 kg/m3, respectively. • Fish were fed daily with a commercial diet of crude protein (42%) and crude fat (18%). Sea urchins were fed twice a week with the seaweed harvested from the IMTA system itself. • During the trial, every other week, a water sample was collected from each tank, 0, 1, 3, 6, and 12 h after feeding, for monitoring ammonia (NH4/NH3), nitrites, and phosphates levels, using commercial kits. • At the beginning and end of the trial period, fish were group weighed and the diameter of the sea urchins was measured. • The seaweed was also weighed at the beginning of the trial and every 7 days; during this time total biomass was readjusted whenever needed to maintain the initial density. Total feed intake of fish was measured daily.
- 12. Cont… (Ref:Marta Correia etal.2020) • A small scale IMTA system was built similarly to the aforementioned experimental units, using four 5 L aquaria. Three of them were used to place each IMTA species and were provided with aeration (air pumps). • The fourth aquarium was used as a water storage tank. A water pump was placed in this aquarium to allow recirculation of the water originating from the seaweed aquarium back to the aquarium containing the fed species. • The three aquaria with the cultured species were placed on uneven levels so that water could circulate by gravity, successively from the first to the second aquarium and from there to the third one. • Marine fish were placed in the first aquarium (highest level), mussels or sea-urchins in the second aquarium and the seaweed in the third. • The most relevant aspect was the adjustment of the biomass density in each aquarium, which was set to 7–10 kg/m3 for fish species, 20–25 kg/m3 for sea-urchin/mussels and 1–2 kg/m3 for seaweeds. • The activity started by assembling this IMTA system, and afterward students followed the effects of excretion/consumption of some organic and inorganic wastes on the levels of nutrients in the aquaria. • Firstly, water circulation through the IMTA system was turned on and the system was left to stabilize for 2 h. • After this period the water pump was switched off. This was taken as time zero of the experiment. • Water parameters of each aquarium were then measured at time zero and every half an hour for the next 90 or 120 min. • Ammonia (NH4/NH3), nitrates, phosphates, and pH were measured with simple kits available at pet shops. Other colorimetric methods available in schools can also be used.
- 13. Cont… (Ref:Marta Correia etal.2020)
- 14. Performance of European seabass, sea urchin and seaweed obtained for the two experimental laboratorial scale IMTA systems &Water quality parameters of the IMTA prototype (Ref:Marta Correia etal.2020) • IMTA as an environmentally sustainable food production system, addressing the problem of food production, food security, and improved nutrition, is directly related to various Sustainable Development Goals (SDG) of the United Nations 2030 Agenda; namely, SDG2 (Zero hunger), SDG3 (Good health and well-being), SDG 4 (Quality education), SDG 13 (Climate action) and SDG14 (Life below water). • Finally, spreading scientific knowledge on aquaculture, its state of the art methods as well as its safety and quality, is crucial to increase the public perception and acceptability of its products and increase their consumption.
- 15. Case studies: IMTA • In temperate waters Canada, Chile, China, Ireland, South Africa, the United Kingdom of Great Britain and Northern Ireland (mostly Scotland) and the United States of America are the only countries to have IMTA systems near commercial scale. France, Portugal and Spain have ongoing research projects related to the development of IMTA. • The countries of Scandinavia, especially Norway, have made some individual groundwork towards the development of IMTA, despite possessing a large finfish aquaculture network (Barrington et al. 2009). • Studies have focussed on the integration of seaweeds with marine fish culturing for the past fifteen years in Canada, Japan, Chile, New Zealand, Scotland and the USA. • The integration of mussels and oysters as bio-filters in fish farming has also been studied in a number of countries, including Australia, USA, Canada, France, Chile, and Spain. • Recent IMTA research includes a focus on seaweeds, bivalves and crustaceans. Studies conducted in an IMTA systems incorporating Gracilaria lemaneiformis and Chlamys farreri in North China have shown that a bivalve/seaweed biomass ratio from 1:0.33 to 1:0.80 was preferable for efficient nutrient uptake and for maintaining lower nutrient levels. • Results indicate that G. lemaneiformis can efficiently absorb the ammonium and phosphorus from scallop excretion. I • n China, Seaweeds, Gracilaria lemaneiformis, grown over 5 km of culture ropes near fish net pens on rafts increased the density from 11.16 to 2025 g/m in a 3-month growing period. The scaling up of culture area during the following 4 months to 80 km of rope, reported an increase in culture density on ropes to 4250 g/m. • An increase in the biomass of Gracilaria (in the culture area) to 340 t wet weight was estimated due to its culture in close proximity to fish net pens. Different work along similar principles has taken place elsewhere.
- 16. • Studies on IMTA have been carried on the East coast of Canada, where Atlantic salmon (Salmo salar), kelp (Saccharina latissima and Alaria esculenta) and blue mussel (Mytilus edulis) were reared together at several IMTA sites in the Bay of Fundy. • The study has shown that the growth rates of kelp and mussels cultured in proximity to fish farms have been 46 and 50% higher, respectively, than at control sites. • Several other studies have also reflected on the faster growth of mussels and oysters grown adjacent to fish cages. • This reflects increase in nutrients and food availability from the finfish cages. Taste tests of mussels grown in conventional aquaculture and mussels grown at these IMTA sites showed no discernible difference; meat yield in the IMTA mussels was, however, higher. • Findings of the economic models have also shown that increased overall net productivity of a given IMTA site can lead to increased profitability of the farm compared with monoculture. • Studies from land-based systems indicated that seaweeds can remove between 35% and 100% of dissolved nitrogen produced by fed species. • The capacity of seaweeds in open-water cultures to remove nutrients from the water column can be estimated based upon the fraction of available nutrients, which are bound by the seaweeds at any given point in time. • Experimental data and mass balance calculations indicated that a large area of seaweed cultivation, up to one ha for each ton of fish standing stock, would be required for the full removal of the excess nitrogen associated with a commercial fish farm.
- 17. Cont… • The open-sea IMTA in India is very recent; however, various investigations have been carried out on the beneficial polyculture of the various mariculture species. • Combined culture of compatible species of prawns and fishes is of considerable importance in the context of augmenting yield from the field and effective utilisation of the available ecological niches of the pond system. • Finfish culture, Etroplus suratensis, in cages erected within the bivalve farms (racks) resulted in high survival rates and growth of the finfish in the cages. Co-cultivation of Gracilaria sp. • at different stocking densities with Feneropenaeus indicus showed nutrient removal from shrimp culture waste by the seaweed. The ratio of 3:1 was found suitable for the co-cultivation. • The seaweed (600 g) was able to reduce 25% of ammonia, 22% of nitrate and 14% of phosphate from the shrimp (200 g) waste. • Polyculture of shrimp with molluscs helps in breaking down organic matter efficiently and serves as an important food source for a range of organisms and also either directly or indirectly provides shelter or creates space for associated organism, thus increasing the species diversity of the ecosystem. • Studies have shown that an individual mussel can filter between 2-5 l/h and a rope of mussel more than 90000 l/day. • The culture of mussels could thus be used in the effective removal of phytoplankton and detritus as well as to reduce the eutrophication caused by aquaculture.
- 18. Cont… • Along the east coast of India, the introduction of IMTA in open sea cage farming yielded 50% higher production of seaweed, Kappaphycus alvarezii, when integrated with finfish farming of Rachycentron canadum. • Open-sea mariculture of finfishes when integrated with raft culture of green mussels, P. viridis resulted in slight, but not significant reduction in nutrients along Karnataka. • The beneficial effect of combining bivalves such as mussels, oyster and clams as bio-filters in utilizing such nutrient rich aquaculture effluents has been documented in estuaries. • In a tropical integrated aquaculture system, the farming of bivalves (Crassostrea madrasensis) along with finfish (Etroplus suratensis) resulted in controlling eutrophication effectively (Viji et al, 2013, 2015). • The filter feeding oysters improved the clarity of the water in the farming area; thereby reducing eutrophication. • The optimal co-cultivation proportion of fish to oysters reported was 1:0.5 in this farming system.
- 19. Benefits of IMTA Effluent bio-mitigation: • Mitigation of effluents through the use of bio-filters which are suited to the ecological niche of the aquaculture site. This can solve a number of the environmental challenges posed by monoculture aquaculture. Increased profits through diversification: Increased overall economic value of an operation from the commercial by-products that are cultivated and sold. • The complexity of any bio-filtration comes at a significant financial cost. • To make environmentally friendly aquaculture competitive, it is necessary to raise its revenues. • By exploiting the extractive capacities of co-cultured lower trophic level taxa, the farm can obtain added products that can outweigh the added costs involved in constructing and operating an IMTA farm. • The waste nutrients are considered in integrated aquaculture not a burden but a resource, for the auxiliary culture of bio-filters. Improving local economy: Economic growth through employment (both direct and indirect) and product processing and distribution
- 20. Cont… • Form of ‘natural’ crop insurance: Product diversification may offer financial protection and decrease economic risks when price fluctuations occur, or if one of the crops is lost to disease or inclement weather. • Disease control: Prevention or reduction of disease among farmed fish can be provided by certain seaweeds due to their antibacterial activity against fish pathogenic bacteria. • Increased profits through obtaining premium prices: Potential for differentiation of the IMTA products through eco-labelling or organic certification programmes.
- 21. Challenges • Higher investment: Integrated farming in open sea requires a higher level of technological and engineering sophistication and up-front investment. • Difficulty in coordination: If practised by means of different operators (e.g. independent fish farmers and mussel farmers) working in concert, it would require close collaboration and coordination of management and production activities. • Increase requirement of farming area: While aquaculture has the potential to release pressure on fish resources and IMTA has specific potential benefits for the enterprises and the environment, fish farming competes with other users for the scarce coastal and marine habitats. • Stakeholder conflicts are common and range from concerns about pollution and impacts on wild fish populations to site allocation and local priorities. • The challenges for expanding IMTA practice are therefore significant although it can offer a mitigation opportunity to those areas where mariculture has a poor public image and competes for space with other activities. • Difficulty in implementation without open water leasing policies: Few countries have national aquaculture plans or well developed integrated management of coastal zones. • This means that decisions on site selection, licensing and regulation are often ad hoc and highly subject to political pressures and local priorities. • Moreover, as congestion in the coastal zone increases, many mariculture sites are threatened by urban and industrial pollution and accidental damage.
- 22. References • Angel, D. and Freeman S., 2009. Integrated aquaculture (INTAQ) as a tool for an ecosystem approach in the Mediterranean Sea. In: Integrated mariculture: a global review (ed. Soto, D.). FAO Fisheries and Aquaculture Technical Paper, 529: 133-183. Barrington, K., Chopin, T. and Robinson, S., 2009. Integrated multi-trophic aquaculture (IMTA) in marine temperature waters. In: Integrated mariculture: a global review (ed. Soto, D.). FAO Fisheries and Aquaculture Technical Paper, 529: 7-46. Chopin, T. 2006. Integrated multi-trophic aquaculture. What it is, and why you should care… and don’t confuse it with polyculture. North. Aquac., 12 (4): 4. • Ahmed, N., Thompson, S., and Glaser, M. (2019). Global aquaculture productivity, environmental sustainability, and climate change adaptability. Environ. Manag. 63, 159–172. doi: 10.1007/s00267-018-1117-3 • https://www.frontiersin.org/articles/10.3389/fmars.2020.00156/full • Geetha Sasikumar and C. S. Viji.CMFRI eprints. Integrated Multi-Trophic Aquaculture Systems (IMTA). Winter School on Technological Advances in Mariculture for Production Enhancement and Sustainability. http://eprints.cmfri.org.in/10666/1/7.%20Geetha%20Sasikumar.pdf