Performance of a constructed wetland in treating brackish wastewater from commercial recirculating and super-intensive shrimp growout systems

A recirculating aquaculture system was developed for treating Pacific white shrimp (Litopenaeus vannamei) production wastewater using an integrated vertical-flow (IVF) and five connected integrated horizontal flow (IHF) constructed wetlands as water treatment filters for mesohaline conditions (8.25‰-8.26‰ salinity). The constructed wetlands demonstrated the ability to reduce total nitrogen, total ammonia nitrogen, nitrite nitrogen, nitrate nitrogen, total phosphorous, chemical oxygen demand, and total suspended solids to levels significantly lower than those in effluents from culture tanks. Various water quality parameters in the culture tanks were deemed suitable for shrimp culture. The actual ratio of wetland area (A(w)) to culture tank area (A(t)) was 1.1439, and the estimated optimal ratio A(w)/A(t) was approximately 1. The IVF-IHF wetlands showed flexibility and reliability in consistently removing the main pollutants from commercial recirculating and super-intensive shrimp growout systems throughout the culture period.     

Biofloc Technology: Emerging Microbial Biotechnology for the Improvement of Aquaculture Productivity

With the significant increases in the human population, global aquaculture has undergone a great increase during the last decade. The management of optimum conditions for fish production, which are entirely based on the physicochemical and biological qualities of water, plays a vital role in the prompt aquaculture growth. Therefore, focusing on research that highlights the understanding of water quality and breeding systems’ stability is very important. The biofloc technology (BFT) is a system that maximizes aquaculture productivity by using microbial biotechnology to increase the efficacy and utilization of fish feeds, where toxic materials such as nitrogen components are treated and converted to a useful product, like a protein for using as supplementary feeds to the fish and crustaceans. Thus, biofloc is an excellent technology used to develop the aquaculture system under limited or zero water exchange with high fish stocking density, strong aeration, and biota. This review is highlighted on biofloc composition and mechanism of system work, especially the optimization of water quality and treatment of ammonium wastes. In addition, the advantages and disadvantages of the BFT system have been explained. Finally, the importance of contemporary research on biofloc systems as a figure of microbial biotechnology has been emphasized with arguments for developing this system for better production of aquaculture with limited natural resources of water.Key words: biofloc, BFT, aquaculture, microbes, water quality, wastes     

Biological treatment of shrimp production wastewater

Over the last few decades, there has been an increase in consumer demand for shrimp, which has resulted in its worldwide aquaculture production. In the United States, the stringent enforcement of environmental regulations encourages shrimp farmers to develop new technologies, such as recirculating raceway systems. This is a zero-water exchange system capable of producing high-density shrimp yields. The system also produces wastewater characterized by high levels of ammonia, nitrate, nitrite, and organic carbon, which make waste management costs prohibitive. Shrimp farmers have a great need for a waste management method that is effective and economical. One such method is the sequencing batch reactor (SBR). A SBR is a variation of the activated sludge biological treatment process. This process uses multiple steps in the same reactor to take the place of multiple reactors in a conventional treatment system. The SBR accomplishes equalization, aeration, and clarification in a timed sequence in a single reactor system. This is achieved through reactor operation in sequences, which includes fill, react, settle, decant, and idle. A laboratory scale SBR was successfully operated using shrimp aquaculture wastewater. The wastewater contained high concentrations of carbon and nitrogen. By operating the reactors sequentially, namely, aerobic and anoxic modes, nitrification and denitrification were achieved as well as removal of carbon. Ammonia in the waste was nitrified within 4 days. The denitrification of nitrate was achieved by the anoxic process, and 100% removal of nitrate was observed within 15 days of reactor operation.     

The role of selective breeding and biosecurity in the prevention of disease in penaeid shrimp aquaculture

About 3.5 million metric tons of farmed shrimp were produced globally in 2009 with an estimated value greater than USD$14.6 billion. Despite the economic importance of farmed shrimp, the global shrimp farming industry continues to be plagued by disease. There are a number of strategies a shrimp farmer can employ to mitigate crop loss from disease, including the use of Specific Pathogen Free (SPF), selectively bred shrimp and the adoption of on-farm biosecurity practices. Selective breeding for disease resistance began in the mid 1990s in response to outbreaks of Taura syndrome, caused by Taura syndrome virus (TSV), which devastated populations of farmed shrimp (Litopenaeus vannamei) throughout the Americas. Breeding programs designed to enhance TSV survival have generated valuable information about the quantitative genetics of disease resistance in shrimp and have produced shrimp families which exhibit high survival after TSV exposure. The commercial availability of these selected shrimp has benefitted the shrimp farming industry and TSV is no longer considered a major threat in many shrimp farming regions. Although selective breeding has been valuable in combating TSV, this approach has not been effective for other viral pathogens and selective breeding may not be the most effective strategy for the long-term viability of the industry. Cost-effective, on-farm biosecurity protocols can be more practical and less expensive than breeding programs designed to enhance disease resistance. Of particular importance is the use of SPF shrimp stocked in biosecure environments where physical barriers are in place to mitigate the introduction and spread of virulent pathogens.     

INTEGRATING SEAWEEDS INTO MARINE AQUACULTURE SYSTEMS: A KEY TOWARD SUSTAINABILITY

The rapid development of intensive fed aquaculture (e.g. finfish and shrimp) throughout the world is associated with concerns about the environmental impacts of such often monospecific practices, especially where activities are highly geographically concentrated or located in suboptimal sites whose assimilative capacity is poorly understood and, consequently, prone to being exceeded. One of the main environmental issues is the direct discharge of significant nutrient loads into coastal waters from open-water systems and with the effluents from land-based systems. In its search for best management practices, the aquaculture industry should develop innovative and responsible practices that optimize its efficiency and create diversification, while ensuring the remediation of the consequences of its activities to maintain the health of coastal waters. To avoid pronounced shifts in coastal processes, conversion, not dilution, is a common-sense solution, used for centuries in Asian countries. By integrating fed aquaculture (finfish, shrimp) with inorganic and organic extractive aquaculture (seaweed and shellfish), the wastes of one resource user become a resource (fertilizer or food) for the others. Such a balanced ecosystem approach provides nutrient bioremediation capability, mutual benefits to the cocultured organisms, economic diversification by producing other value-added marine crops, and increased profitability per cultivation unit for the aquaculture industry. Moreover, as guidelines and regulations on aquaculture effluents are forthcoming in several countries, using appropriately selected seaweeds as renewable biological nutrient scrubbers represents a cost-effective means for reaching compliance by reducing the internalization of the total environmental costs. By adopting integrated polytrophic practices, the aquaculture industry should find increasing environmental, economic, and social acceptability and become a full and sustainable partner within the development of integrated coastal management frameworks.     

Effect of carbon to nitrogen (C:N) ratio on nitrogen removal from shrimp production waste water using sequencing batch reactor

The United States Marine Shrimp Farming Program (USMSFP) introduced a new technology for shrimp farming called recirculating raceway system. This is a zero-water exchange system capable of producing high-density shrimp yields. However, this system produces wastewater characterized by high levels of ammonia, nitrite, and nitrate due to 40% protein diet for the shrimp at a high density of 1,000 shrimp per square meter. The high concentrations of nitrate and nitrite (greater than 25 ppm) are toxic to shrimp and cause high mortality. So treatment of this wastewater is imperative in order to make shrimp farming viable. One simple method of treating high-nitrogen wastewater is the use of a sequencing batch reactor (SBR). An SBR is a variation of the activated sludge process, which accomplishes many treatment events in a single reactor. Removal of ammonia and nitrate involved nitrification and denitrification reactions by operating the SBR aerobically and anaerobically in sequence. Initial SBR operation successfully removed ammonia, but nitrate concentrations were too high because of carbon limitation in the shrimp production wastewater. An optimization study revealed the optimum carbon to nitrogen (C:N) ratio of 10:1 for successful removal of all nitrogen species from the wastewater. The SBR operated with a C:N ratio of 10:1 with the addition of molasses as carbon source successfully removed 99% of ammonia, nitrate, and nitrite from the shrimp aquaculture wastewater within 9 days of operation.     

Impact of Aquaculture on Commercial Fisheries: Fishermen’s Local Ecological Knowledge

The Bay of Fundy along the southwest coast of New Brunswick, Canada is one of the most densely stocked finfish aquaculture areas in the world. An inshore multi-species fishery that dates back to the earliest European settlement shares these waters, and has been the economic mainstay of coastal communities. These inshore fishermen are increasingly displaced by the expanding aquaculture industry. A recent study conducted among fishermen in Southwest New Brunswick recorded their observations about the environmental impact of finfish aquaculture and the consequences for their commercial fishery. Fishermen all reported significant environmental degradation around aquaculture sites. Within 2 years of an operation being established, fishermen reported that gravid female lobsters as well as herring avoid the area, scallop and sea urchin shells become brittle, scallop meat and sea urchin roe becomes discolored. The use of chemicals to control sea lice on farmed salmon has also caused lobster, crab and shrimp kills. These and other concerns suggest that more comprehensive and detailed studies are required to establish the environmental and economic interactions of aquaculture and the inshore fishery, as well as on the stocks on which that fishery rely. The study also points to the need for more effective use of fishermen’s knowledge in designing such studies.     

Mangroves as filters of shrimp pond effluent: predictions and biogeochemical research needs

Preliminary estimates of the ratio of mangrove forest: shrimp pond area necessary to remove nutrients from shrimp pond effluent are made using budgets of nitrogen and phosphorus output for semi-intensive and intensive shrimp ponds combined with estimates of total net primary production in Rhizophora-dominated mangrove forests in tropical coastal areas. If effluent is delivered directly to mangrove forest plots, it is estimated that, depending on shrimp pond management, between 2 and 22 hectares of forest are required to filter the nitrogen and phosphorus loads from effluent produced by a 1 hectare pond. While such ratios may apply to small scale, integrated shrimp aquaculture — mangrove forestry farming systems, the variability in mangrove hydrodynamics makes it difficult to apply such ratios at a regional scale. Before mangroves can be used to strip shrimp pond effluent more research is required on the effects that high ammonia and particulate organic matter loads in pond effluent have on nutrient transformations in mangrove sediments and on forest growth.     

Virus diseases of farmed shrimp in the Western Hemisphere (the Americas): a review

Penaeid shrimp aquaculture is an important industry in the Americas, and the industry is based almost entirely on the culture of the Pacific White Shrimp, Litopenaeus vannamei. Western Hemisphere shrimp farmers in 14 countries in 2004 produced more than 200,000 metric tons of shrimp, generated more than $2 billion in revenue, and employed more than 500,000 people. Disease has had a major impact on shrimp aquaculture in the Americas since it became a significant commercial entity in the 1970s. Diseases due to viruses, rickettsial-like bacteria, true bacteria, protozoa, and fungi have emerged as major diseases of farmed shrimp in the region. Many of the bacterial, fungal and protozoan caused diseases are managed using improved culture practices, routine sanitation, and the use of chemotherapeutics. However, the virus diseases have been far more problematic to manage and they have been responsible for the most costly epizootics. Examples include the Taura syndrome pandemic that began in 1991-1992 when the disease emerged in Ecuador, and the subsequent White Spot Disease pandemic that followed its introduction to Central America from Asia in 1999. Because of their socioeconomic significance to shrimp farming, seven of the nine crustacean diseases listed by the World Animal Organization (OIE) are virus diseases of shrimp. Of the seven virus diseases of penaeid shrimp, five are native to the Americas or have become enzootic following their introduction. The shrimp virus diseases in the Americas are increasingly being managed by exclusion using a combination of biosecurity and the practice of culturing domesticated specific pathogen-free (SPF) stocks or specific pathogen-resistant (SPR) stocks. Despite the significant challenges posed by disease, the shrimp farming industry of the Americas has responded to the challenges posed by disease and it has developed methods to manage its diseases and mature into a sustainable industry.     

生态理念下对虾健康养殖发展建议

随着对虾产业的不断壮大,对虾类水产养殖过程中疾病频发、水环境污染等问题日益突出,其品种和养殖模式的多样化使得这一矛盾更加难以解决.本文回顾了中国对虾产业50年发展过程中的疾病伴生史,并从生态学视角重新审视了对虾病原体的发生、进化以及与对虾免疫系统的关系,进而提出避免药物滥用、防重于治、注重对虾选育工作、基于生态系统方法...     

Viral infections of aquatic animals with special reference to Asian aquaculture

Worldwide, the number of communicable diseases of animals raised in aquaculture continue to increase. Viral infections of cultivated shellfish, crustacea, and finfish have been frequently recognized in the past few years. In the Asian regions, penaeid shrimp and several teleost fish underwent epizootics associated with heavy losses in aquaculture. Baculoviruses are particularly harmful to shrimp and prawns. Herpes-, irido-, reo-, or rhabdovirus-like agents can cause outbreaks in fish farms. Viral diseases are important limiting factors in the expansion of aquaculture. However, studies on viral infections of aquatic animals have been focused primarily on economically important farmed fish. Therfore, certain viral diseases of teleost fish are relatively well understood. In contrast, our knowledge of viral infections of farmed aquatic invertebrates is still very spare. Although a great number of viruses have been detected in farmed molluscs and crustaceans, the pathogenicity and epizootiology of most of the agents is not known.     

The application of bioflocs technology to protect brine shrimp (Artemia franciscana) from pathogenic Vibrio harveyi

Aims: To study the potential biocontrol activity of bioflocs technology. Methods and Results: Glycerol‐grown bioflocs were investigated for their antimicrobial and antipathogenic properties against the opportunistic pathogen Vibrio harveyi. The bioflocs did not produce growth‐inhibitory substances. However, bioflocs and biofloc supernatants decreased quorum sensing‐regulated bioluminescence of V. harveyi. This suggested that the bioflocs had biocontrol activity against this pathogen because quorum sensing regulates virulence of vibrios towards different hosts. Interestingly, the addition of live bioflocs significantly increased the survival of gnotobiotic brine shrimp (Artemia franciscana) larvae challenged to V. harveyi. Conclusions: Bioflocs grown on glycerol as carbon source inhibit quorum sensing‐regulated bioluminescence in V. harveyi and protect brine shrimp larvae from vibriosis. Significance and Impact of the Study: The results presented in this study indicate that in addition to water quality control and in situ feed production, bioflocs technology could help in controlling bacterial infections within the aquaculture pond.     

Domestication causes rapid changes in heart and brain morphology in Atlantic cod (<Emphasis Type="Italic">Gadus morhua</Emphasis>)

Brain and heart development is very plastic in teleost fishes, and receptive to changes in social and environmental conditions. Domestication in salmonids has been reported to result in pronounced changes in both heart and brain morphology. In particular, a high prevalence of heart deformities has been reported in farmed salmonids, which has been linked to increased stress responsiveness that can impair survival of both farmed and escaped fish. Here we report for the first time that significant changes in heart and brain morphology occur following domestication of Atlantic cod (Gadus morhua), an emerging aquaculture species. Juvenile farmed cod developed significantly larger hearts and smaller brains, by weight, compared to their wild conspecifics. These differences occurred within the first captive generation, suggesting that they were driven largely by the strong contrast in environmental and social conditions experienced within their respective rearing environments. Changes in brain and heart morphology, as a consequence of domestication could affect the well-being and survival of Atlantic cod raised under intensive aquaculture conditions.     

Increasing production in Korean shrimp farms with white-spot syndrome virus PCR-negative brood stock

White-spot syndrome virus (WSSV) is a devastating, infectious virus affecting shrimp. Although sensitive techniques involving PCR have been developed to assist farmers in screening shrimp (brood stock) for WSSV prior to stocking ponds, such practices have not yet been applied in Korea. Despite the rationality of implementing screening, there has been some doubt as to whether the stocking of WSSV-PCR-negative fry epidemiologically decreases white-spot disease outbreaks. Here, we report a retrospective analysis of data from shrimp farms in the western coast of Korea where WSSV-PCR-negative brood stocks were used to stock rearing ponds. A total of 366 shrimp from Heuksan Island were sampled for WSSV with PCR. Of the tested shrimp, 7.2% (28 brood stocks) were identified as WSSV positive; only WSSV-PCR-negative shrimp were used for brood stocks. Total unit production (final shrimp production/ the area of the ponds) was higher, at 1.96, in ponds where WSSV-PCR-negative shrimp were used, as compared with 1.02 in other ponds in Korea in 2004. This retrospective analysis of WSSV in Korea may be useful to the shrimp aquaculture industry, suggesting a testable hypothesis that may contribute to the eventual control of WSSV outbreaks.     

Relative nursery function of oyster, vegetated marsh edge, and nonvegetated bottom habitats for juvenile white shrimp Litopenaeus setiferus

Shallow estuarine habitats, including vegetated marsh edge (VME), oyster reefs (oyster), and nonvegetated soft bottom (NVB), provide important functions for estuarine resident and estuarine-dependent species. A paucity of information exists concerning relative nursery value of these habitats for juvenile fishes and invertebrates. In Grand Bay, MS and Weeks Bay, AL, National Estuarine Research Reserves (NERR), this study evaluated the potential of the three habitats to serve as nurseries by quantifying habitat-specific density, size, growth, and survival of juvenile white shrimp Litopenaeus setiferus. Drop sampling in Oct 2003 and Jul 2004 indicated that white shrimp density was significantly greater in oyster and VME when compared with adjacent NVB. No significant difference occurred in density between oyster and VME. Significantly larger shrimp were collected in NVB, intermediate-sized shrimp were collected in oyster, and smaller shrimp were collected in VME. Using field enclosures to study growth of juvenile white shrimp we found significantly higher growth in oyster when compared with NVB and VME. Predator mesocosm experiments indicated that when blue crabs were used as predators, white shrimp juveniles experienced significantly higher survival rates in VME and NVB when compared with oyster. Our study suggests that juvenile white shrimp may select for oyster over NVB because of higher food availability and not necessarily for refuge needs from predation by blue crabs. In addition, juvenile habitat needs may shift with individual growth, indicating that the relative nursery value of a habitat is not inclusive for all juvenile sizes. Similar to VME, oyster provides an important function in the juvenile stages of white shrimp and should be examined further as a potential nursery habitat.     

Indel-II region deletion sizes in the white spot syndrome virus genome correlate with shrimp disease outbreaks in southern Vietnam

Sequence comparisons of the genomes of white spot syndrome virus (WSSV) strains have identified regions containing variable-length insertions/deletions (i.e. indels). Indel-I and Indel-II, positioned between open reading frames (ORFs) 14/15 and 23/24, respectively, are the largest and the most variable. Here we examined the nature of these 2 indel regions in 313 WSSV-infected Penaeus monodon shrimp collected between 2006 and 2009 from 76 aquaculture ponds in the Mekong Delta region of Vietnam. In the Indel-I region, 2 WSSV genotypes with deletions of either 5950 or 6031 bp in length compared with that of a reference strain from Thailand (WSSV-TH-96-II) were detected. In the Indel-II region, 4 WSSV genotypes with deletions of 8539, 10970, 11049 or 11866 bp in length compared with that of a reference strain from Taiwan (WSSV-TW) were detected, and the 8539 and 10970 bp genotypes predominated. Indel-II variants with longer deletions were found to correlate statistically with WSSV-diseased shrimp originating from more intensive farming systems. Like Indel-I lengths, Indel-II lengths also varied based on the Mekong Delta province from which farmed shrimp were collected.     

Implications of high animal by-product feed inputs in life cycle assessments of farmed Atlantic salmon

Purpose

Animal by-products may be increasingly relied upon to satisfy nutritional requirements of salmonids and other fed aquaculture species as demand for fish meal outpaces supply. Previous studies of aquaculture supply chains have included either no animal by-product inputs or small inputs of poultry by-products. Australian Atlantic salmon production includes high use of feed inputs derived from poultry and mammalian by-products and provides a case study to explore the environmental implications and methodological challenges associated with these inputs.

Methods

Life cycle assessment was carried out on a vertically integrated salmon production system in Tasmania, representing approximately 40% of Australian Atlantic salmon production. The system included feed production, smolt/juvenile production, farm grow-out, processing and packaging, and distribution of head-on gutted salmon to market. Impacts from animal production were allocated to by-products on a gross chemical energy basis. Scenario analyses were conducted to determine the extent to which changes in feed conversion ratio, feed composition, and other variables affect results. Sensitivity analysis was carried out on the allocation method for fishery and animal by-products.

Results and discussion

Environmental impacts associated with Tasmanian salmon fed high quantities of animal by-products were markedly higher than those of previously assessed systems. All impacts were driven by feed production with the exception of eutrophication potential, which was driven equally by feed production and nutrient loss during grow-out. Animal by-products accounted for the majority of all impacts from feed production. Adopting a feed composition without animal by-products would result in dramatic improvements, including a 70% decrease in greenhouse gas emissions. Allocation choice had a clear effect on results, with biophysical allocation methods placing much more burden from animal production on fed systems than economic or no-impact allocation methods.

Conclusions

The use of animal by-product inputs in aquaculture feeds has a substantial effect on the environmental profile of farmed salmon products. The magnitude of this effect is dependent on the allocation method chosen for the treatment of products and by-products in upstream systems. The high impact of such systems recognizes the environmental cost of future aquaculture production that may rely more on intensive and high-impact animal production inputs as more efficient fishery inputs become increasingly limited relative to demand.

     

Effects of temperature, salinity, and carbon: nitrogen ratio on sequencing batch reactor treating shrimp aquaculture wastewater

In order to improve the water quality in the shrimp aquaculture, we tested a sequencing batch reactor (SBR) for the treatment of shrimp wastewater. A SBR is a variation of the activated sludge biological treatment process. This process uses multiple steps in the same tank to take the place of multiple tanks in a conventional treatment system. The SBR accomplishes pH correction, aeration, and clarification in a timed sequence, in a single reactor basin. This is achieved in a simple tank, through sequencing stages, which includes fill, react, settle, decant, and idle. The wastewater from the Waddell Mariculture Center, South Carolina was successfully treated using a SBR. The wastewater contained high concentration of carbon and nitrogen. By operating the reactor sequentially, viz, aerobic, anaerobic, and aerobic modes, nitrification and denitrification were achieved as well as removal of carbon. We optimized various environmental parameters such as temperature, salinity, and carbon and nitrogen ratio (C:N ratio) for the best performance of SBR. The results indicated that the salinity of 28-40 parts per thousand (ppt), temperature range of 22-37 degrees C, and a C:N ratio of 10:1 produced best results in terms of maximum nitrogen and carbon removal from the wastewater. The SBR system showed promising results and could be used as a viable treatment alternative in the shrimp industry.     

Anammox bacteria in different compartments of recirculating aquaculture systems

Strict environmental restrictions force the aquaculture industry to guarantee optimal water quality for fish production in a sustainable manner. The implementation of anammox (anaerobic ammonium oxidation) in biofilters would result in the conversion of both ammonium and nitrite (both toxic to aquatic animals) into harmless dinitrogen gas. Both marine and freshwater aquaculture systems contain populations of anammox bacteria. These bacteria are also present in the faeces of freshwater and marine fish. Interestingly, a new planctomycete species appears to be present in these recirculation systems too. Further exploitation of anammox bacteria in different compartments of aquaculture systems can lead to a more environmentally friendly aquaculture practice.     

Comparative life cycle assessment (LCA) of Tilapia in two production systems: semi-intensive and intensive

Purpose

In order to meet the upscaling demand of food products worldwide, the aquaculture industry has been expanding within the last few years in developed countries. Major expansions of aquaculture farming occurred in many developed countries such as Bangladesh, Indonesia, and Egypt. Egypt ranks ninth in fish farming production worldwide and first on Africa. Egypt has the largest aquaculture industry in Africa which represents two-thirds of African aquaculture production. Tilapia production accounts for 75.5 % of aquaculture production in Egypt. Tilapia aquaculture production has grown exponentially in recent decades until it reached 4.5 million tonnes in 2012 placing Egypt as the second worldwide producer of tilapia after China. The production of tilapia is practiced in different production systems including intensive and semi-intensive systems. These production systems require different resources and impact differently on the environment. The aim of the current study was to model the environmental performance of tilapia production and compare semi-intensive and intensive production systems. The main questions were the following: What are the different impacts of tilapia production on the environment? Which production system is more environmentally friendly? What are the preferable practices for better environmental performance and sustainable ecofriendly industry of Tilapia production?

Methods

Life cycle assessment (LCA) was employed to determine the environmental impacts of tilapia production and compare semi-intensive and intensive production systems. Data for life cycle inventory were collected from two case study farms for tilapia production in Egypt. Four impact categories were taken into consideration: Global Warming Potential (GWP), Acidification Potential (AP), Eutrophication Potential (EP), and Cumulative Energy Demand (CED).

Results and discussion

LCA revealed that production of tilapia in intensive farming has less impact on GWP, AP, and CED, while its impact on EP is higher than in semi-intensive farming. The identified impacts from 1-tonne live weight production of tilapia were the following: GWP 960.7 and 6126.1 kg CO₂ eq; AP 9.8 and 24.4 kg SO₂ eq; EP 14.1 and 6.3 kg PO₂ eq; and CED 52.8 GJ and 238.3 GJ eq in intensive and semi-intensive systems, respectively.

Conclusions

Fish meal production and energy consumption were the major contributors to different impact indicators in both systems. An overall improvement in environmental performance for tilapia production can be achieved by novel feed formulations that have better environmental performance. Energy consumption is a major area for improvement as well, as proper energy management practices will reduce the overall impact on the environment.