Integrated Aquaculture System Research Articles

Growth, protein and carbohydrate contents in Ulva rigida and Gracilaria bursa-pastoris integrated with an offshore fish farm

Low-technology practices are generally the rule when cultivating marine macroalgae, and they do not necessarily comply with sustainability requirements. When integrated with other marine organisms in land-based setups, seaweed culture can be sustainable also providing environmental benefits. Major challenges of such integrated aquaculture systems, however, are in sea-based setups. The current study examined the growth rates of Ulva rigida and Gracilaria bursa-pastoris, as well as their protein and carbohydrate contents, when exposed to different distances from an offshore, fed-fish cage system. Nutrient levels in seawater were consistently high downstream from the fish cages, significantly enhancing the specific growth rates and cellular contents of starch and soluble protein in these two seaweeds. Specifically, daily maximal growth rates were 17 % day−1 for U. rigida and 10 % day−1 for G. bursa-pastoris, maximal starch contents were 22 and 21 %, respectively, and maximal protein contents were on a dry weight basis 7 and 13 %, respectively. When repositioned at low ambient nutrient levels for 48 h, the starch and the carbohydrate levels increased by 129 and 131 % for U. rigida and by 198 and 150 % for G. bursa-pastoris, respectively. Altogether, this study supports implementing future viable mean of sustainable macroalgae cultivation by taking advantage of excessive nutrients released from an offshore fish farm.

Can oysters control eutrophication in an integrated fish-oyster aquaculture system?

is a serious problem occurring in ponds or estuaries where fish culture is practised. A possible solution to this problem is to raise oysters in an integrated culture with fish to improve water clarity and to help remove excess nutrients. In order to determine the effects that cultured oysters have on the environment, an experimental study was performed in the Moothakunnam region of the Vembanad lake in the Ernakulam District during February-November, 2012. The study was performed in four cages (1× 1× 1 m) referred to as treatments T1, T2, T3 and T4. The four treatments used fish ( Etroplus suratensis ) and oysters (Crassostrea madrasensis) in the ratio of 1:0.3, 1:0.5, 1:0.7 and 1:0 respectively. Several parameters were measured and compared between the four treatments, and these included temperature, pH, salinity, dissolved oxygen, biochemical oxygen demand, chemical oxygen demand, total suspended solids, ammonia, nitrite, nitrate and orthophosphate. Results showed that the parameters, DO, BOD, COD, TSS, ammonia and orthophosphate varied with different treatments and months. However, the contents of nitrite and nitrate showed variation only with respect to months. The eutrophication index (E) values calculated for the four treatments were 9.45 ± 4.41, 5.25 ± 3.23, 11.32 ± 6.17 and 11.52 ± 5.45 respectively. The lower E value obtained was for T2 which supports the conclusion that oysters can control eutrophication in an integrated aquaculture system. The optimal co-cultivation proportion of fish to oysters obtained from the present study was 1:0.5.

Pond management strategies for small-scale aquaculture in northern Vietnam: fish production and economic performance

The traditional pond aquaculture in northern Vietnam is a plant-based integrated aquaculture system using poor-quality pond inputs (macrophytes, farm by-products, manures). Most applied feeds are palatable solely to the grass carp (Ctenopharyngodon idella), which is the main species in traditional fish polyculture. Secondary species are malnourished as the natural food productivity is diminished by uncontrolled water flow through and high turbidity. Mass mortalities of grass carp lead to high financial losses for the farmers. To improve the fish production, researchers developed a semi-intensive pond management in stagnant water in which common carp was cultured as the main species with supplemental fertilization and pelleted feeds based mainly on locally available resources. In this study, the traditional and semi-intensive pond management was compared in six ponds for fish production, nutrient efficiencies and economic net benefit. The use of higher-quality feed and fertilizer inputs under semi-intensive pond management resulted in higher fish yields of 228 ± 42 kg × 1,000 m−2 compared to 88 ± 44 kg × 1,000 m−2 under traditional management and higher net economic benefit of 3,848,000 ± 1,469,000 VND × 1,000 m−2 under semi-intensive compared to 846,000 ± 3,753,000 VND × 1,000 m−2 under traditional management. Under semi-intensive management, 11.5 % of applied total nitrogen was transferred into fish biomass while under traditional management, 4.4 % of applied total nitrogen converted into fish biomass.

Effect of the ascidian Styela clava on the growth of small holothurians of the species Apostichopus japonicus

We studied the effect of the common ascidian Styela clava on the growth of small holothurians of the species Apostichopus japonicus (Selenka, 1867). In a traditional aquaculture system, the oxygen consumption rates, ammonia excretion rates, and ingestion rates of small A. japonicus were reduced significantly, which suggested that this group was stressed by the presence of large A. japonicus, and that this stress grew stronger with time. Oxygen consumption rates, ammonia excretion rates, and ingestion rates of small A. japonicus in an integrated aquaculture (IA) system with S. clava, microalgae, and A. japonicus were higher than those observed in the traditional culture system. Metabolic and digestive enzymes were more active in small A. japonicus in the IA system than in those in the traditional aquaculture system. These results suggest that the IA model did not affect the growth of large A. japonicas, but produced a marked positive impact on the growth of small individuals.

Antibiotic resistance and genetic diversity of Escherichia coli isolates from traditional and integrated aquaculture in South China

This study investigated antibiotic resistance profiles including antibiotic resistance frequencies, resistance genes and resistance patterns in Escherichia coli strains isolated from traditional and integrated aquaculture systems in South China by using antibiotic susceptibility testing and real time polymerase chain reaction (PCR) technique. The E. coli isolates were found to be resistant to at least one antibiotic among 12 antibiotics. Higher resistance frequencies to ampicillin, sulfamethoxazole, trimethoprime, streptomycin and tetracycline were found compared to the rest antibiotics. Among the 10 tetracycline resistance genes detected in the resistant isolates, the most prevalent tetracycline resistance genes were tetA, tetW and tetB with the frequency of 69.7%, 63.5% and 21.9%, respectively. Three sulfonamide resistance genes were detected in these resistant isolates, with their detection frequencies in the following order: sul2 (55.3%) > sul3 (28.2%) > sul1 (6.2%). Four resistance genes mainly encoding extended-spectrum β-lactamases (ESBLs) were detected in these resistant isolates, with the detection frequencies of blaTEM (28.4%) > blaOXA (9.7%) > blaCTX (9.3%) > blaCARB (5.2%) > blaSHV (0.0%). It was found that the integrated aquaculture system exhibited generally higher prevalence of antibiotic resistance than the traditional aquaculture system. An integrated aquaculture system could facilitate development of bacterial resistance and spread of the antibiotic resistance genes, and consequently become an important reservoir of resistance genes.

Risks for fishborne zoonotic trematodes in Tilapia production systems in Guangdong province, China

Guangdong province is the most important region for tilapia culture in China. However, it is also an endemic region for fishborne zoonotic trematodes (FZT), which pose a risk to human food safety and health. A study was designed to assess the status of trematode parasite infections in tilapia aquaculture systems as an indicator of potential risks from FZT associated with consumption of tilapia. Tilapia from nursery and grow-out ponds were sampled from monoculture, polyculture and integrated aquaculture systems. The results from 388 tilapia examined revealed a very low prevalence (1.5%) of trematode infections (Heterophyidae and Echinostomatidae). Integrated systems using animal manure and latrine wastes as fertilizer did not show a higher prevalence of FZT. Because it was not clear whether the low risk of infection was attributable to existing effective pond management practices or a low risk of spillover of FZT from area sylvatic reservoir hosts, a survey of local wild-caught fish was conducted. Five species of FZT were discovered from a total of 271 wild-caught fish and a mean infection density of 4.0 metacercariae/100g; FZT discovered included intestinal flukes (Haplorchis spp., Procerovum varium, and Metagonimus spp.) and metacercariae tentatively identified as Clonorchis sinenesis. The common occurrence of FZT in wild-caught fish suggests that the presence of FZT in local wild animal reservoirs is substantial, and that although the current aquaculture management systems for tilapia are generally effective in preventing transmission of these parasites into tilapia production systems, the improvement of pond management practices and biosecurity must be maintained at a high level.

Total organic carbon budget of integrated aquaculture system of sea cucumberApostichopus japonicus, jellyfishRhopilema esculentaand shrimpFenneropenaeus chinensis

The total organic carbon (TOC) budget of the integrated aquaculture system of sea cucumber Apostichopus japonicus, jellyfish Rhopilema esculenta and shrimp Fenneropenaeus chinensis was investigated in a cofferdam (1.202 km2) for 13-month field study. The results showed that the total input of TOC to the system was 498 300 kg year−1, of which photosynthesis accounted for 26.8% of input TOC. The TOC production of the sea cucumber was 3668 kg year−1, and that of the jellyfish and the shrimp was 714 kg year−1. The TOC utilization rate of the input TOC by sea cucumber production was 7.4‰, and that of the integrated system increased by 18.9% than that of sea cucumber monoculture model through integration with jellyfish and shrimp. The outflow TOC from the system was 336 600 kg year−1, which account for 92.7% of the inflow TOC. The integrated aquaculture system not only produce aquatic products, but also eliminate 7.3% of the inflow TOC, therefore, this system was not only a production system of aquatic products, but also an organic matter purification system for the coastal environment. The TOC utilization rate of the system can be probably improved by means of increasing stocking density of the sea cucumber and/or the shrimp.

Development of a seaweed species-selection index for successful culture in a seaweed-based integrated aquaculture system

Integrated multi-trophic aquaculture (IMTA) has been proposed as a concept that combines the cultivation of fed aquaculture species (e.g., finfish/shrimp) with extractive aquaculture species (e.g., shellfish/seaweed). In seaweed-based integrated aquaculture, seaweeds have the capacity to reduce the environmental impact of nitrogen-rich effluents on coastal ecosystems. Thus, selection of optimal species for such aquaculture is of great importance. The present study aimed to develop a seaweed species-selection index for selecting suitable species in seaweed-based integrated aquaculture system. The index was synthesized using available literature-based information, reference data, and physiological seaweed experiments to identify and prioritize the desired species. Undaria pinnatifida, Porphyra yezoensis and Ulva compressa scored the highest according to a seaweed-based integrated aquaculture suitability index (SASI). Seaweed species with the highest scores were adjudged to fit the integrated aquaculture systems. Despite the application of this model limited by local aquaculture environment, it is considered to be a useful tool for selecting seaweed species in IMTA.

Experiments on an integrated aquaculture system (seaweeds and marine fish) on the Red Sea coast of Saudi Arabia: efficiency comparison of two local seaweed species for nutrient biofiltration and production

AbstractSeaweeds absorb inorganic nutrient wastes from mariculture and reduce their undesirable environmental effects. Mariculture in Saudi Arabia is increasing rapidly, thus, to exploit aquaculture wastes and to reduce coastal pollution risks, local seaweeds were cultured using mariculture effluents in integration on the Red Sea coast. The aim of the present study was to test integrated aquaculture of seaweed and marine fish (Oreochromis spilurus) for the first time in Saudi Arabia and to determine the seaweeds, Ulva lactuca and Gracilaria arcuata, biomass production and inorganic nutrient bioremediation capabilities. Results showed that G. arcuata grew at a significantly higher rate (2.71% wet weight day−1) than U. lactuca (1.77% wet weight day−1). The biomass yield (42.38 g wet weight m−2 day−1) and net yield (91.11 g wet weight day−1) of G. arcuata were also significantly higher than U. lactuca (27.39 g wet weight m−2 day−1 and 58.89 g wet weight day−1, respectively). Gracilaria arcuata removed 0.45 g m−2 day−1 of total ammonia nitrogen (TAN) with 80.15% removal efficiency and 1.03 g m−2 day−1 of soluble phosphate with 41.06% efficiency. Ulva lactuca removed 0.42 g m−2 day−1 of TAN with 83.06% removal efficiency and 1.07 g m−2 day−1 of soluble phosphate with 41.11% efficiency. Total tissue carbon of both species reached 25.1–26.9% and nitrogen content reached 3.0–3.2% of dry weight. The C/N ratio for both seaweeds was <10, indicating that nitrogen was not a limiting factor in culture. Both seaweeds are suitable for integrated aquaculture and bioremediation, but G. arcuata has relatively higher growth potential.

Land-based integrated aquaculture systems: Sustainability assessment of a pilot scale system

Land-based integrated aquaculture systems: Sustainability assessment of a pilot scale system

CARBON/NUTRIENT BALANCE IN RELATION TO BIOMASS PRODUCTION AND HALOGENATED COMPOUND CONTENT IN THE RED ALGA ASPARAGOPSIS TAXIFORMIS (BONNEMAISONIACEAE)(1).

We tested how the availability of carbon and nitrogen determines both the production of Asparagopsis taxiformis (Delile) V. Trevis. and content of the two major halocarbons, bromoform and dibromoacetic acid. The halogenated secondary metabolites of Asparagopsis species are particularly interesting from an applied perspective due to their remarkable antimicrobial activity. Terrestrial ecologists named the relationship between resources and secondary metabolites as the carbon (C)/nutrient balance (CNB) hypothesis. This relationship was tested both in the laboratory, with a factorial analysis using different concentrations of total ammonia (TAN) and dissolved inorganic carbon (DIC), and in an integrated aquaculture system where TAN and DIC fluxes of fish effluent were manipulated. The total C/N content of A. taxiformis biomass cultivated in laboratory was highly significantly linearly related to the content of both halocarbons, as predicted by the CNB hypothesis. A. taxiformis cultivated at low levels of carbon and high levels of nitrogen (N) (lowest C/N ratio) had the lowest content in both halogenated metabolites. Increased availability of CO2 in the medium resulted in a general higher halocarbon content in the biomass, even though the effect was only statistically significant for bromoform at high levels of N. The farm experiments supported the results of the laboratory experiments. DIC fluxes had the highest effect on the production of both bromoform and biomass, as shown by multiple regression analysis. In A. taxiformis integrated aquaculture, C, rather than N, is the most important factor affecting the production of biomass and of valuable halocarbon secondary metabolites.

Incidence and antimicrobial resistance of enteropathogens isolated from an integrated aquaculture system

To evaluate an integrated aquaculture system, microbiological analyses of water used in this system were carried out and the incidence and antimicrobial resistance of enteropathogens were determined in the related ecosystem. Microbiological analysis was undertaken for Salmonella sp., Shigella sp., Vibrio sp. and Aeromonas sp. The disc-diffusion method was performed according to the Clinical and Laboratory Standards Institute. Water samples tested had 32.9% of faecal coliform rates (≤1600 per 100 ml) in accordance with WHO for pisciculture in wastewater. Salmonella spp. were detected in 14.5% of the samples. From a total of 33 strains, 15.1% were resistant to one or two antimicrobial drugs tested and multidrug resistance was not observed. Aeromonas spp. were identified in 91.6% of the samples. From a total of 416 strains, resistance to one antimicrobial class was observed in 66.3% and multidrug resistance in 37.7%. This system reflects the community profile, drawing attention to the circulation of pathogens, because the genes coding for resistance to classical antibiotics and broad spectrum are a public health problem. The reuse of water resources requires continuous monitoring as the system is subject to treatment failure, which can result in the spread of bacterial pathogens.

Investigation into the sustainability of organic aquaculture of Atlantic cod (Gadus morhua)

Wild stocks of Atlantic cod (Gadus morhua) are low. With fisheries in decline, continued demand for cod has led to a fledgling aquaculture industry and current forecasts call for rapid growth. However, critics blame aquaculture of carnivorous species for further depleting fish stocks and for its wider effects on the marine environment. We examine the activities of Johnson Seafarms, a sea-cage organic cod farming facility in the Shetland Islands, to investigate whether “organic” cod farming can be environmentally, economically, and socially sustainable. Data were collected via public questionnaires and interviews with aquaculture experts. The results show that, before it closed in 2008, Johnson Seafarms was addressing the environmental concerns traditionally associated with aquaculture of carnivorous species and that economic viability is possible as a market exists for organically farmed cod at prices higher than for wild fish. We conclude that organic cod farming, as was practiced in the Shetland Islands, is sustainable on that scale. While the industry has room for measured expansion, overexpansion would increase pressure on natural systems, undermining environmental and, ultimately, social and economic sustainability. Producers and regulators should consider alternative techniques, including land-based or integrated aquaculture systems. Any development should be accompanied by further research regarding the industry’s sustainability.

Evaluating the economic potential of horizontally integrated land-based marine aquaculture

Coastal aquaculture development is frequently associated with negative environmental impacts, competition for resources and conflict. Consequently, a new paradigm of ecologically-sound, socially responsible and economically viable aquaculture development based on systems-thinking, resource use efficiency and joint analysis with stakeholders is needed. Horizontal integration, combining aquaculture production systems to optimise resource use efficiency constitutes a promising approach in this regard. Research shows that an array of horizontally integrated systems are technically viable, however, few studies have combined this with consideration of the managerial, financial and economic demands. A bioeconomic modelling approach was employed here to assess the broader implications of adopting horizontally integrated land-based marine aquaculture in temperate and warm water settings. The temperate system, integrating fish, microalgae and shellfish culture and a polishing lagoon was developed on the Atlantic coast of France. Modelling outcomes predicted that when all costs were considered this approach failed to generate a positive Internal Rate of Return (IRR) over ten years. Subsequent scenarios showed a worthwhile return (ten-year IRR 19.4%) was generated when land and labour opportunity costs were omitted and a 20% premium on products included. The warm water system developed near Eilat, Israel combined sea urchins, shrimp and seaweed culture with a constructed wetland. Assuming baseline production of one million sea urchins annually from year three onwards, modelling outcomes showed a reasonable ten-year IRR of 18%. Reducing sea urchin mortality from 15% to 9% annually resulted in an IRR of 29.4%, while assuming that Salicornia spp. production would reach 33 kg m−2 y−1 in the wetland resulted in an IRR of 133.4%. Findings suggest that bioeconomic modelling can contribute to the optimisation of horizontally integrated aquaculture systems, helping elucidate promising scenarios and identify key constraints and priorities for targeted research and development. Bioeconomic modelling of other horizontal integration strategies, such as shrimp culture with shellfish, macroalgae and mangrove wetlands could elucidate economically viable approaches to much needed ecologically-sound and socially responsible practices. However, modelling should be supplemented by market analysis, including assessment of consumer attitudes, comprehensive risk assessment, ethical review, environmental impact assessment and joint assessment with stakeholders. Moreover, an enabling institutional framework is a prerequisite to more widespread adoption of horizontal integration; policy initiatives and regulatory tools focused on internalising environmental costs of aquaculture development will be critical.

Physiological Responses of Porphyra yezoensis Ueda (Bangiales, Rhodophyta) Exposed to High Ammonium Effluent in a Seaweed-based Integrated Aquaculture System

Porphyra yezoensis is known to act as a biofilter against nutrient-rich effluent in seaweed-based integrated aquaculture systems. However, few studies have examined its physiological status under such conditions. In this study, we estimated the photosynthetic activity of P. yezoensis by chlorophyll fluorescence of PSII (<TEX>${\Delta}F/F'm$</TEX> and relative <TEX>$ETR_{max}$</TEX>) using the Diving-PAM fluorometer (Walz, Germany). In addition, bioremediation capacity, tissue nutrients, and C:N ratio of P. yezoensis were investigated. The ammonium concentration in seawater of seaweed tank 4 decreased from <TEX>$72.1{\pm}2.2$</TEX> to <TEX>$33.8{\pm}0.4{\mu}M$</TEX> after 24 hours. This indicates the potential role of P. yezoensis in removing around 43% of ammonium from the effluents. Tissue carbon contents in P. yezoensis were constant during the experimental period, while nitrogen contents had increased slightly by 24 hours. In comparison with the initial values, the <TEX>${\Delta}F/F'm$</TEX> and <TEX>$rETR_{max}$</TEX> of P. yezoensis had increased by about 20 and 40%, respectively, after 24 hours. This indicates that P. yezoensis condition improved or remained constant. These results suggest that chlorophyll fluorescence is a powerful tool in evaluating the physiological status of seaweeds in a seaweed-based integrated aquaculture system.

Aquaculture of detritivorous fish in China: status and perspective.

Abstract The aim of this review is to give a description of aquaculture of detritivorous fish in China. China has a long history of using aquaculture. With the increasing demand for fishery products, intensive aquaculture has been encouraged to a great degree, which has also led to a series of environmental, technical and social problems. Besides physical, chemical and mechanical removal of waste by sedimentation and microsieving, a biologically and technically feasible method called integrated aquaculture has been proposed to reduce environmental impacts. Bivalve molluscs, seaweeds and detritivorous fish are considered as suitable subjects for integrated culture. A model showed that sedimentary N decreased from 37% of the total original nutrients to 8.5% after the introduction of bivalve molluscs and seaweeds into aquaculture. Four detritivorous fish, Plagiognathops microlepis , Xenocypris davidi , Squaliobarbus curriculus and Liza haematocheila , are now used in aquaculture in China. To determine the most suitable initial integrated culture level of detritivorous fingerlings, a dynamic model was constructed based on a computer simulation method according to the following principle: the level of scavenging by detritivorous fish equals the level of waste left by the main culture object. Selecting suitable detritivorous fish species, solving the technical problems of artificial propagation and determining the initial culture level of selected species are three key problems associated with maintaining an effective integrated aquaculture system. Raising awareness about the importance of 'clean' aquaculture and performing corresponding scientific research should be encouraged.

Integrating filamentous ‘green tide’ algae into tropical pond-based aquaculture

‘Green tide’ algae bloom in eutrophic environments with fast growth rates and efficient nutrient uptake. These same characteristics are sought after for algae in integrated aquaculture systems. We examined the effect of two key variables, salinity and total ammonia nitrogen (TAN), on the growth of three filamentous ‘green tide’ algae, Cladophora coelothrix, Chaetomorpha indica and Ulva sp. Survival and growth were first determined across the extremes of salinity in ponds (0 to 45‰). Subsequently, the interactive effects of salinity (15, 36 and 45‰) and TAN (0–700 µmol l − 1 ) were quantified using a factorial design. All species have a broad tolerance to salinity (ranging from 5 to 45‰) with each having a different optimum for growth ( C. coelothrix 30‰, C. indica 20‰ and Ulva sp. 15‰). A significant interaction (salinity ⁎ TAN ⁎ species) further demonstrated that responses vary between algae. C. indica and Ulva sp. have their highest growth rates of ~ 14% day − 1 and ~ 25% day − 1 respectively at higher TAN levels (> 70 µmol l − 1 ) but at different salinities. Growth of C. coelothrix was optimum at lower TAN levels (35 µmol l − 1 ) and 36‰, but surprisingly was inhibited at the highest TAN. C. coelothrix and C. indica were also cultured in an operational bioremediation pond. High growth rates of C. coelothrix were maintained in situ (~ 6% day − 1 ), while C. indica performed poorly. Finally, TAN removal rates were calculated using natural densities and in situ growth rates demonstrating that ‘green tide' algae have broad application across the environmental variables that characterize tropical pond-based aquaculture.

Efficient bioremediation of total organic carbon (TOC) in integrated aquaculture system by marine sponge Hymeniacidon perleve

The aim of this study is to investigate the potential of using marine sponge Hymeniacidon perleve to remove total organic carbon (TOC) in integrated aquaculture ecosystems. In sterilized natural seawater (SNSW) with different concentrations of TOC, H. perleve removed approximately 44-61% TOC during 24 h, with retention rates of ca. 0.19-1.06 mg/h .g-fresh sponge, however no particulate selectivity was observed. The highest initial TOC concentration, in which about 2.7 g fresh sponges could remove TOC effectively in 0.5-L SNSW, is 214.3-256.9 mg/L. The highest capacity of TOC removal and clearance rate (CR) by H. perleve is ca. 25.50 mg-TOC/g-fresh sponge and 7.64 mL/h . g-fresh sponge within 24 h, respectively. Until reaching the highest TOC removal capacity, the TOC removal capacity and clearance rate of H. perleve increased with initial TOC concentration, and dropped dramatically thereafter. After reaching the highest removal capacity, H. perleve could only remove relatively lower TOC concentration in seawater in subsequent run. The TOC removal kinetics in SNSW by H. perleve fitted very well with a S-shaped curve and a Logistic model equation (R(2) = 0.999). In different volumes of SNSW with a fixed initial TOC concentration, the weight/volume ratio of sponge biomass and SFNSW was optimized at 1.46 g-fresh sponge/1-L SNSW to achieve the maximum TOC removal. When co-cultured with marine fish Fugu rubripes for 15 days, H. perleve removed TOC excreted by F. rubripes with similar retention rates of ca. 0.15 mg/h . g-fresh sponge, and the sponge biomass increased by 22.8%.

Nutrient Optimization and Computerized Decision Support Program in Recirculating Integrated Aquaculture System

There are many research activities to improve sustainable aquaculture and agriculture production in the wide world. Sustainable aquaculture is referred to as production of aquatic commodities through farming activities with social, economic and environmental sustainability. A series of experiments were conducted to compare different inorganic and organic fertilizers to improve production of Macrobrachium rosenbergii and to make a decision support program in an artificial sustainable aquaculture-agriculture system. Simply, nutrient wastes from culture tanks were used to fertilize hydroponics or terrestrial plants production via irrigation water. The sustainability and success functioning of the whole system were involved to manage and optimize the use of supplemented minerals, diet and desirable environment for each compartment (prawn, plant and microorganisms).The first experiment was made to evaluate the tolerance of M. rosenbergii in different levels of inorganic fertilizer (EC) formulated in nutrient film technique (NFT) vegetable production system. Results of the first experiment indicated that desirable growth rate of M. rosenbergii was obtained using 0.1 to 0.5EC of supplemental liquid fertilizer. High concentration of potassium (117-177 mg l-1), ammonia (0.72-1.05 mg l-1) and copper (0.04-0.06 mg l-1) inhibited the growth rate of M. rosenbergii in integrated culture system. The second experiment was carried out to assess the effects of different nutrient and stocking density on different population of M. rosenbergii in polyculture system. A different range of inorganic and organic fertilizer was used in the polyculture of plant and freshwater prawn species. Overall results indicated that essential concentration of nutrients, source and M. rosenbergii stocking density have played a major role in the effectiveness of suitable range of minerals in integrated production system. The results also demonstrated that 0.5 EC liquid inorganic fertilizer was not suitable to provide optimum nutrients and chicken manure is still an important fertilizer even in indoor integrated culture system. Finally, a comparative study was conducted to evaluate the optimum level of chicken manure and formulated inorganic nutrients in an artificial integrated culture system. The results indicated that high density culture of M. rosenbergii juveniles (380-400 individual m-2) in fiberglass tanks is possible by the installation of artificial substrate and controlling of nutrient concentration in system. Moreover the addition of aeration tank significantly improved the quality of water (DO and pH) and freshwater prawn growth (1343.0 g/tank) in recirculated polyculture system. The application of 70 g m-3 chicken manure alone encouraged growth of benthic and periphyton algae in culture tanks. The overall observation illustrated the desirable combination of supplemental liquid fertilizer and chicken manure is essential to obtain best growth for each compartment in sustainable polyculture system. A visual expert program (IAAS) was adopted to improve managing and develop technical operation in an artificial integrated culture system. The operation of the polyculture system required the specific knowledge, developing and application of computer systems to excellent operation, control of water quality variables, dissolved nutrients and feed to avoid the production of toxic substance and increase self efficiency and sustainability of the culture system. The accuracy of IAAS expert program was evaluated by polynomial and linear regression techniques through additional experiment. The comparison of results (yield and survival) in expert and real culture system represents higher variation of survival, prawn and plant yields in abnormal culture system. Moreover the evaluation processes demonstrated succeed performance of IAAS expert program in prediction results of optimized integrated culture system (with low variation). In aquaculture, the success estimation of production depends largely on the state of physical and chemical parameters which define optimal culture conditions.

The influence of stocking density, light and temperature on the growth, production and nutrient removal capacity of Porphyra dioica (Bangiales, Rhodophyta)

The optimal conditions for growth of Porphyra dioica gametophytes were investigated in the laboratory, focusing on bioremediation potential. Porphyra dioica is one of the most common Porphyra species along the northern coast of Portugal and can be found year-round. The influence of stocking density and photon flux density (PFD) on the growth, production and nutrient removal was tested. Maximum growth rates, up to 33% per day, were recorded with 0.1 g fw l − 1 at 150 and 250 μmol photons m − 2 s − 1 . Growth rate decreased significantly with increasing stocking density. Productivity (g fw week − 1 ) had an inverse trend, with more production at the higher stocking densities. At 150 μmol m − 2 s − 1 and with 1.5 g fw l − 1 , 1.4 g fw week − 1 were produced. At this PFD, there was no significant difference in production between 0.6 to 1.5 g fw l − 1 . Nitrogen (N) content of the seaweeds decreased with increasing stocking densities and PFDs. The maximum N removal was recorded at 150 μmol m − 2 s − 1 , with 1.5 g fw l − 1 stocking density (1.67 mg N day − 1 ). However, the N removed by thalli at 50 μmol photons m − 2 s − 1 was statistically equal to that at 150 and 250 μmol photons m − 2 s − 1 , at a stocking density of 1.0 g fw l − 1 . The influence of temperature and photoperiod on growth and reproduction was also assessed. Growth rates of P. dioica were significantly affected by temperature and photoperiod. In this experiment (with 0.3 g fw l − 1 stocking density), the highest growth rate, 27.5% fw day − 1 , was recorded at 15 °C and 16 : 8¯, L : D¯. Male thalli started to release spermatia 21 days after the beginning of the experiment, in temperatures from 10 to 20 °C and with 10, 12 and 16 h of day length. Unfertilized female-like thalli were observed at 10 to 20 °C, under all photoperiods tested. Growth of these thalli declined after 4 weeks. By then, formation of young bladelets in the basal portion of these thalli was observed. After 7 weeks all biomass produced was solely due to these vegetatively propagated young thalli, growing 22.4% to 26.1% day − 1 . The results of this study showed that P. dioica appears to be a candidate as a nutrient scrubber in integrated aquaculture systems.