Traditional Aquaculture Systems Research Articles

EMERGING TRENDS: THE RISE OF BIOFLOC FISH FARMING IN MODERN AQUACULTURE

Modern aquaculture is continually evolving to meet the growing demand for sustainable and efficient methods of fish production. One emerging trend gaining considerable attention is biofloc fish farming, a revolutionary approach that integrates microbial-rich environments to enhance water quality and optimize fish growth. This paper provides an overview of the key principles and benefits of biofloc technology, shedding light on its potential to shape the future of aquaculture. Biofloc technology involves the cultivation of dense communities of microorganisms, primarily bacteria and algae, within the aquaculture system. These microorganisms form aggregates known as bioflocs, creating a dynamic ecosystem that contributes to water purification and nutrient recycling. This approach stands in contrast to traditional aquaculture systems that rely on water exchange, often leading to environmental concerns and increased resource usage. The main advantages of biofloc fish farming include improved water quality, enhanced biosecurity, and increased production efficiency. This paper reviews case studies and research findings that showcase the successful implementation of biofloc technology in different fish species, highlighting its versatility and adaptability. The potential economic benefits, coupled with environmental sustainability, position biofloc fish farming as a viable and attractive option for modern aquaculture. As the global demand for seafood continues to rise, exploring innovative and sustainable practices becomes imperative. The rise of biofloc fish farming represents a paradigm shift in aquaculture practices, offering a promising solution to address the challenges of traditional systems while fostering a more environmentally responsible and economically viable industry.

Metabolomic characterization of Chinese sturgeon (Acipenser sinensis) in semi-intensive and recirculating aquaculture systems

The present study investigated the blood biochemistry and metabolic profiles of Chinese sturgeons (Acipenser sinensis) reared in semi-intensive traditional aquaculture systems (TAS) and recirculating aquaculture systems (RAS). Results of serum biochemical indices in the RAS group showed that the levels of total protein (TP), albumin (ALB), globulin (GLO), high-density lipoprotein cholesterol (HDL), low-density lipoprotein cholesterol (LDL), cholesterol (CHOL), and alkaline phosphatase (ALP) were higher than those in the TAS group (p < 0.05). TAS group induced significantly higher levels of glucose (GLU), triglycerides (TG), aspartate transaminase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH), lactic acid (LD), and blood urea nitrogen (BUN) than RAS group (p < 0.05). Additionally, a total of 3123 metabolites were detected, including 152 up-regulated and 861 down-regulated metabolites, totally 1013 metabolites were significantly different (VIP > 1 and p < 0.05). The analysis of these different metabolites revealed that the top four significantly metabolic pathways (p-value or FDR < 0.05) were neomycin, kanamycin, and gentamicin synthesis, glycerophospholipid metabolism, folate biosynthesis, and phosphatidylinositol signaling system, which are related to aminoglycosides, lipids, and pterin metabolism. There were 28 metabolites enriched in the four metabolic pathways, including 7 different types of antibiotics, 16 glycerophospholipids, and 5 pterins. Overall, Chinese sturgeons reared in TAS showed higher concentrations of 25 metabolites, and only three metabolites with higher significant activities showed in RAS, including PE (18:1(9Z)/22:6 (4Z, 7Z, 10Z, 13Z, 16Z, 19Z)), PC (14:0/P-18:1(9Z)), and Folic Acid. In conclusion, our results revealed differences in the biochemical indices, metabolites, and metabolic pathways of Chinese sturgeons reared in TAS and RAS and confirmed that RAS improves fish metabolism and physiological state, providing new insights for sturgeon aquaculture.

IoT Water Quality Monitoring and Control System in Moving Bed Biofilm Reactor to Reduce Total Ammonia Nitrogen.

Traditional aquaculture systems appear challenged by the high levels of total ammoniacal nitrogen (TAN) produced, which can harm aquatic life. As demand for global fish production continues to increase, farmers should adopt recirculating aquaculture systems (RAS) equipped with biofilters to improve the water quality of the culture. The biofilter plays a crucial role in ammonia removal. Therefore, a biofilter such as a moving bed biofilm reactor (MBBR) biofilter is usually used in the RAS to reduce ammonia. However, the disadvantage of biofilter operation is that it requires an automatic system with a water quality monitoring and control system to ensure optimal performance. Therefore, this study focuses on developing an Internet of Things (IoT) system to monitor and control water quality to achieve optimal biofilm performance in laboratory-scale MBBR. From 35 days into the experiment, water quality was maintained by an aerator's on/off control to provide oxygen levels suitable for the aquatic environment while monitoring the pH, temperature, and total dissolved solids (TDS). When the amount of dissolved oxygen (DO) in the MBBR was optimal, the highest TAN removal efficiency was 50%, with the biofilm thickness reaching 119.88 μm. The forthcoming applications of the IoT water quality monitoring and control system in MBBR enable farmers to set up a system in RAS that can perform real-time measurements, alerts, and adjustments of critical water quality parameters such as TAN levels.

Effect of biofloc technology at varies biological factors on the growth performance and water quality in cultivation of red hybrid tilapia

Aquaculture is one of the important food-producing sectors. However, the effluent of the aquaculture system consists of pollutants such as nitrogenous compounds and the ample usage of water for traditional aquaculture systems. Therefore, biofloc technology was developed in the aquaculture industry in the 1980s to improve the water quality of the system and increase the fish production. The purpose of this experimental work is to investigate the effect of biological factors on the growth performance of fish and the water quality of the biofloc technology (BFT) aquaculture system for red hybrid tilapia cultivation. In this study, 3 biological factors such as the carbon-to-nitrogen ratio, stocking density and the feeding rate were studied under BFT. Parallel experiments in thirteen suspended growth tanks were carried out within (10:1-20:1) C/N ratio, (1%-5%) feeding rate and (20-80 fish m-3) stocking density for 10 weeks. Growth rate of fish and water quality data such as ammonia, nitrite and nitrate concentrations were collected weekly during the study. The results revealed that the 20:1 C/N ratio gave the best water quality. Feeding rate at 4% of body weight produced good growth performance of the tilapia species and the higher stocking densities lead to lower water quality and survival rate.

Plankton community in Penaeus vannamei nurseries with synbiotic system under different frequencies of adjustment on Ca:Mg:K ratio in low salinity water

The aim of this study was to evaluate plankton communities in Penaeus vannamei nurseries under different frequencies of adjustment on Ca:Mg:K ratio in low salinity water and with synbiotic system. A nursery culture was carried out for 40 days, using 2000 shrimp m⁻³. Following treatments were established: 1IA (Ca:Mg:K ratio adjustment to 1:3:1 on day 1); 2IA (Ca:Mg:K ratio adjustment to 1:3:1 on day 1 and day 20); 3IA (Ca:Mg:K ratio adjustment to 1:3:1 on day 1, day 10, and day 20); SW (seawater - salinity of 31 g L−1); and SWD (seawater diluted to a salinity of 2.3 g L−1). Rice bran processed by probiotic microorganisms was used as an organic carbon source. Treatments did not have a significant effect on phytoplankton and zooplankton composition. However, plankton composition was significantly different over the experimental course. A reduced abundance of Cyanophyta was observed compared to traditional aquaculture systems. This can be explained by the probiotic bacteria addition to the system, along with fertilization, which may have limited the growth of this harmful algae. Throughout the experiment, zooplankton community had a dominance by protozoan microorganisms, such as amoebae and ciliates. The presence of copepods and rotifers was also observed throughout the experimental course. This proves that the use of the synbiotic system provides conditions for the microbial loop development, mimicking a natural environment. Different adjustment frequencies in the water Ca:Mg:K ratio do not significantly change plankton composition in P. vannamei intensive nurseries using low salinity water and synbiotic system. Temporal variation in plankton composition probably occurred due to fertilization of the system with an organic carbon source. The use of the synbiotic system proved to be efficient in microbial loop development, providing the growth of a high load of microorganisms that can influence water quality and shrimp growth in low salinity water.

Managerial Pattern and Work Relations at Traditional Pond in Pangkajene and the Island District (Milkfish Aquaculture Case in Bonto Manai Village)

Improving the quality of traditional farmers on a technical, social and economic scale, is strongly influenced and determined by the capacity to carry out pond business activities related to managerial patterns and work relationships that are formed. This research was conducted in October – December 2021. Milkfish (Chanos-chanos) aquaculture business in Bonto Manai Village was chosen as the case, because the aquaculture system managed by the community is dominated the traditional aquaculture system. The purpose of this research is to analyze the knowledge of traditional aquaculture as a technical practice in managing aquaculture businesses, as well as to analyze the work relations of traditional aquaculture businesses which are internalized in the local culture of the community. The methodology used is a case research method with a descriptive qualitative data analysis approach described in the life history of the informants. The results showed that traditional farmers in milkfish (Chanos-chanos) aquaculture in Bonto Manai Village have acquired knowledge gained through experience passed down from generation to generation, starting from the construction and management of pond subgrade, seed stocking, rearing, harvest and post-harvest. Accompanied by rituals based on belief as a traditional value. The managerial pattern and work relations in the management of traditional pond business have three types of management, namely; aquaculture business which is self managed by the owner of the aquaculture land with involving two to three workers, aquaculture business which is managed based on a leasing system, and aquaculture business which is managed by a rapture system. Keywords: Managerial Pattern, Work Relations, Traditional Pond, Milkfish

Automated, technified and traditional aquaponic systems

Aquaponics are defined as hydroponic crops merged with recirculating aquaculture systems and bacteria, achieving a synergic relationship that takes fish wastewater and uses it in order to grow plants, then the last one in association with nitrifying bacteria are used as a natural filter that removes dissolved nitrogen, ammonia, among others, controlling the fish waste accumulation. Nowadays there are different research areas in aquaponics, from ones focused on the applied techniques in aquaculture and hydroponic sub-systems; through applied sciences such as modeling from both physical and chemical systems; arriving to the types of aquaponics, qualified from technification grades; concluding with fish and plant crop species and their interaction. In this paper a systematic review is carried out in order to observe the research current state in automated, technified and traditional aquaculture systems, thus having a sight of the investigative orientation in this field. This review is based on scientific papers from four databases, taken in March of 2020, obtaining 1356 results, evaluated and filtered for further analysis. From the review it was found that there is an exponential quantity growth in papers per year, moreover, it is noted that the paper fields of greatest concentration are aquaculture, agriculture, environment, water analysis, horticulture and electronics, the most worked species are lettuce (Lactuca sativa) in hydroponic NFT and tilapia (Oreochromis niloticus) in single recirculating aquaponic systems (SRAPS). With the obtained data it was built a diagram that consolidates current research branches in aquaponics.

Sustainability of urban aquaponics farms: An emergy point of view

Aquaponics is a food production system that aims higher sustainability by integrating advantages gained from aquaculture and hydroponic production. Aquaponics aims to mimic the biological process that happens in the natural environment in a controlled production system. As it can be applied to small scales, aquaponics is considered an important alternative for urban regions, which have low availability of agricultural land and water resources. Furthermore, the advantage is that it is located close to final consumers. Aquaponics has been labeled as an environmentally friendly food production system, but its demand for energy and materials cast doubt on its sustainability. A systemic understanding of aquaponics production systems is needed to determine the magnitude and balance between its potentialities and constraints, in which emergy synthesis appears as a powerful tool for this purpose. This study applies emergy synthesis to assess the sustainability of two different (scale and marketable products) urban aquaponics farms in Brazil, but differently from other emergy studies, ecosystem services and disservices are included in the analysis as an attempt to represent the system performance holistically. Results show that the type of materials used in aquaponics infrastructures has the highest influence on total emergy demand. Surprisingly, electricity and fish feed showed a low influence on the total emergy, reinforcing the idea that aquaponics systems have a more efficiency feeding management than traditional aquaculture systems. Besides producing vegetables and fish, the inclusion of ecosystem services highlights the importance of aquaponics for educational and tourism purposes. Finally, the obtained indicators from modeling scenarios revealed that replacing the water source and some materials deserves priority attention to increase the sustainability of urban aquaponics farms.

Growing abalone on a novel offshore platform: An on-site test of the effects of stocking density and diet

Offshore wind-wave resistant mechanized platform is a new mode of abalone farming in China compared to the traditional raft-based system. A series of on-site experiments was conducted to identify the optimal cultivation conditions for this new model. The effects of different stocking densities and diets on the survival rate and growth rate were examined. Abalones were placed in four stocking densities (20, 30, 40, and 50% coverage of available surface area of the culture cage) in this platform, and a control group with one density was set in the traditional aquaculture system. In addition, the effects of different diets (formulated diet, dried Laminaria japonica, and fresh Gracilaria lemaneiformis) for abalone were also studied. Over 240 days, reductions of the survival rate and growth rate of shell length and body weight were observed with the increase of the stocking density. Although the abalone were fed adequate food, the growth rate was limited by the stocking density. Condition index increased with the culture time but decreased with the increase of the stocking density. The growth rates of the shell length and body weight in the formulated diet group were significantly higher than the other two diets. The results also indicated that the medium and large-sized abalone may be more suitable for the new platform, as the medium and large-sized abalone had a higher growth rate when culturing on the mechanized platform, whereas small abalone grew faster on the traditional model. The results from this study can provide fundamental data supporting the offshore mechanized farming of abalone, which will not only promote the yield and reduce the stress of coastal aquaculture environments, but also will contribute to the transformation and upgrading of the abalone farming industry.

FISHERIES DEVELOPMENT AND THE FORMATION OF THE FISH PRODUCTS MARKET IN UKRAINE AND IN THE CENTRAL AND EASTERN EUROPEAN COUNTRIES

FISHERIES DEVELOPMENT AND THE FORMATION OF THE FISH PRODUCTS MARKET IN UKRAINE AND IN THE CENTRAL AND EASTERN EUROPEAN COUNTRIES

Levels and human health risk assessments of heavy metals in fish tissue obtained from the agricultural heritage rice-fish-farming system in China

China began to practice Rice-fish-farming system (RFFS) 1700 years ago. Nowadays, the widely spread of metals could be potential threats to the quality of RFFS fish. In this study, Pb, Cd, Hg, As and Cr as the top five most toxic heavy metals were determined in six species of RFFS fish meat obtained from 7 provinces in south China. The mean concentrations of metals in RFFS fish followed Pb (36.89 μg/kg) > As (33.36 μg/kg) > Cr (18.54 μg/kg) > Hg (16.35 μg/kg) > Cd (2.01 μg/kg), which were mostly lower in comparison with fish from traditional aquaculture systems raised by fish feeds. Grass carp obtained lower metal concentrations compared with other fishes, possibly indicating the importance of feeding habits of RFFS fish. Concentrations of metals in fish and RFFS sediment were in good correlations, and benthic fish obtained high pollution levels, suggesting the accumulation of metals through the direct contact with sediment. Risks assessments coupled with Monte Carlo simulation indicated the potential non-carcinogenic risks and carcinogenic risks decreased following As > Hg > Cr ≈ Pb > Cd, and As > Cr > Cd > Pb, respectively. These results suggested RFFS is still a successful mode of green agriculture.

Economic valuation from direct use of mangrove forest restoration in Balikpapan Bay, East Kalimantan, Indonesia.

Background: The mangrove forests in Balikpapan Bay, Indonesia, have been used as a source of livelihood for local community more than 150 years. Since the natural products of the mangrove forest, such as wood and seafood, are not able to meet the economic needs of the local community, some areas have been converted into brackish water ponds with traditional aquaculture systems. The growth of brackish water ponds over the last five decades has been identified as the main cause of ecosystem destruction. However, the mangrove ecosystem has been restored naturally through tidal action and seeds falling from mangrove trees. Methods: This study focused on the mangrove tree species Rhizophora apiculata, with ages ranging from 3 to 40 years. Initially, the study site (area, 1 ha) was plotted. The study sample size included 30% of the local population, chosen by systematic random sampling. The data collection was undertaken as follows: 1) measurement of the diameter and height of mangrove trees; 2) observation of local fish auctions; and 3) interviewing of fishers and local communities regarding the direct use of the natural products of the mangrove ecosystem. Results: It is suggested that the total income from wood production is IDR 742,425,000 year -1 or US $0.933 person -1 day -1. Furthermore, the total income from fishing is IDR 1,080,353,280 year -1 or US $1.43 person -1 day -1. Pre-thinning income level for wood harvesting is still low. The income difference between wood production and fishing resulted in the rate of overfishing reaching 45.5%. The highest observed wood production was reached at the age of 25 years, and the highest value of mean annual increment (MAI) is 5.39 m 3 ha -1 at the age of 40 years. Conclusions: This study showed that tree thinning, ranging from 90 to 350 trees ha -1, can increase the value of MAI by around 24.5%.

Economic valuation from direct use of mangrove forest restoration in Balikpapan Bay, East Kalimantan, Indonesia

Background: The mangrove forests in Balikpapan Bay, Indonesia, have been used as a source of livelihood for local community more than 150 years. Since the natural products of the mangrove forest, such as wood and seafood, are not able to meet the economic needs of the local community, some areas have been converted into brackish water ponds with traditional aquaculture systems. The growth of brackish water ponds over the last five decades has been identified as the main cause of ecosystem destruction. However, the mangrove ecosystem has been restored naturally through tidal action and seeds falling from mangrove trees. Methods: This study focused on the mangrove tree species Rhizophora apiculata, with ages ranging from 3 to 40 years. Initially, the study site (area, 1 ha) was plotted. The study sample size included 30% of the local population, chosen by systematic random sampling. The data collection was undertaken as follows: 1) measurement of the diameter and height of mangrove trees; 2) observation of local fish auctions; and 3) interviewing of fishers and local communities regarding the direct use of the natural products of the mangrove ecosystem. Results: It is suggested that the total income from wood production is IDR 742,425,000 year -1 or US $0.933 person -1 day -1. Furthermore, the total income from fishing is IDR 1,080,353,280 year -1 or US $1.43 person -1 day -1. Pre-thinning income level for wood harvesting is still low. The income difference between wood production and fishing resulted in the rate of overfishing reaching 45.5%. The highest observed wood production was reached at the age of 25 years, and the highest value of mean annual increment (MAI) is 5.39 m 3 ha -1 at the age of 40 years. Conclusions: This study showed that tree thinning, ranging from 90 to 350 trees ha -1, can increase the value of MAI by around 24.5%.

Economic valuation from direct use of mangrove forest restoration in Balikpapan Bay, East Kalimantan, Indonesia

Background: The mangrove forests in Balikpapan Bay, Indonesia, have been used as a source of livelihood for local community more than 150 years. Since the natural products of the mangrove forest, such as wood and seafood, are not able to meet the economic needs of the local community, some areas have been converted into brackish water ponds with traditional aquaculture systems. The growth of brackish water ponds over the last five decades has been identified as the main cause of ecosystem destruction. However, the mangrove ecosystem has been restored naturally through tidal action and seeds falling from mangrove trees. Methods: This study focused on the mangrove tree species Rhizophora apiculata, with ages ranging from 3 to 40 years. Initially, the study site (area, 1 ha) was plotted. The study sample size included 30% of the local population, chosen by systematic random sampling. The data collection was undertaken as follows: 1) measurement of the diameter and height of mangrove trees; 2) observation of local fish auctions; and 3) interviewing of fishers and local communities regarding the direct use of the natural products of the mangrove ecosystem. Results: It is suggested that the total income from wood production is IDR 742,425,000 year-1 or US $0.933 person-1 day-1. Furthermore, the total income from fishing is IDR 1,019,056,640 year-1 or US $1.28 person-1 day-1. Pre-thinning income level for wood harvesting is still low. The income difference between wood production and fishing resulted in the rate of overfishing reaching 37.3%. The highest observed wood production was reached at the age of 25 years, and the highest value of mean annual increment (MAI) is 5.39 m3 ha-1 at the age of 40 years. Conclusions: This study showed that tree thinning, ranging from 90 to 350 trees ha-1, can increase the value of MAI by around 24.5%.

The effects of marine farm-scale sequentially integrated multi-trophic aquaculture systems on microbial community composition, prevalence of sulfonamide-resistant bacteria and sulfonamide resistance gene sul1

Aquaculture, one of the most important food production practices worldwide, faces serious challenges of mitigating the detrimental impacts of intensive farming on the environment and increased prevalence of antibiotic resistance. To develop an environment-friendly aquaculture system, a land-based and farm-scale sequentially integrated multi-trophic aquaculture (IMTA) system was established for farming Chanos chanos in southwestern Taiwan. In this system, fishes are cultured in combination with organic extractive shellfish and inorganic extractive seaweed. This study aimed to evaluate the prevalence of sulfonamide-resistant bacteria, microbial community structure, and occurrence of sulfonamide resistance genes in the IMTA and traditional aquaculture systems. Water and sediment samples were collected before raising and after harvesting C. chanos. Our results showed that the occurrence of sulfonamide-resistant phenotypes in the IMTA system was comparable with that in influent seawater, while the traditional system exhibited a high sulfonamide resistance rate. Additionally, the traditional system resulted in a deviation of the bacterial community structure from that of seawater. In the water samples from the IMTA system and influent seawater, Proteobacteria and Bacteroidetes were the two dominant phyla, representing approximately 75% and 15% of the community, respectively. In the traditional system, Actinobacteria, constituting 39% of the community, was the dominant bacterial phylum. Thirty-one sulfonamide-resistant bacterial species were isolated. In conclusion, a sequentially IMTA system showed superior ability to maintain the prevalence of antibiotic resistance and the integrity of the bacterial community structure compared to the traditional farming system, representing a potentially valuable aquaculture system for preserving the sustainability of the marine environment.

Large-scale climatic effects on traditional Hawaiian fishpond aquaculture.

Aquaculture accounts for almost one-half of global fish consumption. Understanding the regional impact of climate fluctuations on aquaculture production thus is critical for the sustainability of this crucial food resource. The objective of this work was to understand the role of climate fluctuations and climate change in subtropical coastal estuarine environments within the context of aquaculture practices in Heʻeia Fishpond, Oʻahu Island, Hawaiʻi. To the best of our knowledge, this was the first study of climate effects on traditional aquaculture systems in the Hawaiian Islands. Data from adjacent weather stations were analyzed together with in situ water quality instrument deployments spanning a 12-year period (November 2004 –November 2016). We found correlations between two periods with extremely high fish mortality at Heʻeia Fishpond (May and October 2009) and slackening trade winds in the week preceding each mortality event, as well as surface water temperatures elevated 2–3°C higher than the background periods (March-December 2009). We posit that the lack of trade wind-driven surface water mixing enhanced surface heating and stratification of the water column, leading to hypoxic conditions and stress on fish populations, which had limited ability to move within net pen enclosures. Elevated water temperature and interruption of trade winds previously have been linked to the onset of El Niño in Hawaiʻi. Our results provide empirical evidence regarding El Niño effects on the coastal ocean, which can inform resource management efforts about potential impact of climate variation on aquaculture production. Finally, we provide recommendations for reducing the impact of warming events on fishponds, as these events are predicted to increase in magnitude and frequency as a consequence of global warming.

Erratum to: Restoring habitat and cultural practice in Australia’s oldest and largest traditional aquaculture system

Erratum to: Restoring habitat and cultural practice in Australia’s oldest and largest traditional aquaculture system

Restoring habitat and cultural practice in Australia’s oldest and largest traditional aquaculture system

Lake Condah (Tae Rak) in south-western Victoria, Australia, is one of the world’s most ancient examples of traditional aquaculture, consisting of complex systems of traps and ponds used by Gunditjmara (Indigenous people) over millennia to collect short-finned eel (Anguilla australis) for consumption and trade. Artificial draining of the lake during the nineteenth century reduced surface water retention in the landscape and rendered most of the eel traps inoperable. In this paper, we describe the traditional eel fishery at Lake Condah and its historical and cultural significance to the Gunditjmara people. We document the impacts of European settlement on the traditional eel fishery, and describe the processes and events leading to eventual restoration of the lake and subsequent reactivation of major parts of the traditional aquaculture system. In addition to restoring an important ecological asset to the region, the restoration project provided significant benefits to the Gunditjmara people, including enhanced connection to country and culture, opportunities for economic development and employment, and increased capacity for traditional owners to progress and negotiate outcomes within regulatory and administrative frameworks. Aspects identified as critical to the ultimate success of the Lake Condah restoration project include: open and transparent lines of communication with stakeholders; building of trust and confidence with key individuals over sustained periods; use of strategic and business planning documents to guide activities; commissioning of high quality technical information to support and justify activities; representative leadership structures, and effective use of ‘two-way learning’ across western scientific and indigenous knowledge systems.

Bacterial Community Analysis of Different Sections of a Biofilter in a Full‐Scale Marine Recirculating Aquaculture System

AbstractThe indoor recirculating aquaculture system (RAS) is a sustainable alternative to traditional aquaculture systems, and a biofilter is a crucial component for the stable operation of this system. In this study, the bacterial communities within different sections of the biofilter in a full‐scale RAS for the culture of Tongue Sole Cynoglossus semilaevis were investigated using polymerase chain reaction–based 454 pyrosequencing. A total of 67,368 effective sequences of the 16S rRNA gene with V1–V3 regions were obtained from samples collected from the front section, rear section, and sludge of the biofilter. Using a 3% cut‐off level and sufficient sequencing depth, a total of 5,185 operational taxonomic units (OTUs) were identified in these sequences across all samples. However, a low shared richness of 570 OTUs (11.0% of the reads) was found in all samples, indicating a high diversity of bacterial profiles even in a single biofilter. Based on the SILVA database classifier of phylogenetic taxa, Proteobacteria (average, 35.6%) and Bacteroidetes (average, 30.7%) were found to be the predominant species in all samples, followed by Nitrospirae (6.0%) in the front section, Acidobacteria (7.9%) in the rear section, and Planctomycetes (9.7%) in the sludge. Overall, 404 genera were assigned to all samples. But among the 10 most common genera, only Nitrospira, Owenweeksia, and Marinicella were found in all samples. The results of the phylogenetic analysis suggest that the nitrifying groups of ammonia‐oxidizing bacteria belong to Nitrosomonas clusters, and the nitrite‐oxidizing bacteria are related to Nitrospira and Nitrospina clusters. In summary, our results indicate that the RAS fixed‐film biofilter is a highly species‐rich ecosystem. For this reason, a potential precision‐operated strategy to manage the microbial resources in the biological treatment section in an RAS should be adopted, with consideration being given to the peculiarities and requirements of the species being cultured.

SEARCHING FOR SOLUTIONS IN AQUACULTURE: AQUAPONICS

Aquaponic production combines intensive production with waste recycling and water conservation. Aquaponic join recirculating aquaculture with hydroponics to use nutrient waste from aquaculture as an input to plant growth. Traditional aquaculture systems treat or dispose nutrient-rich wastewater. In aquaponics, the waste products from the fish are converted by a bio-fi lter into soluble nutrients which are absorbed by the plants, and allow “clean” water to be returned back to the fish. Thus, it produces valuable fish protein with a minimal pollution of fresh water resources, while at the same time producing horticultural crops. Fish in aquaponic production systems can be raised in ponds, tanks, or other containers. Plants are grown separately in hydroponic tanks, submerged in water but suspended in gravel, sand, perlite, or porous plastic films, as well as on floating rafts. Systems vary greatly in design and construction, but most perform the following key functions: finfish and plant production, removal of suspended solids, and bacterial nitrification. This review discusses applications, effects and perspective of aquaponics.