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The effect of aeration rates on abalone (Haliotis squamata) juvenile culture in recirculating aquaculture system.
Abstract
Efficient oxygen supply is crucial for the successful cultivation of abalone (Haliotis squamata) in recirculating aquaculture systems (RAS). The aims of this study were to investigate the oxygen consumption rate of H. squamata and evaluate the effects of different aeration rates to determine the optimal flow rate for abalone nurseries. Four aeration flow rates (0.4, 0.8, 1.2, and 1.6 L min −1) were tested using a completely randomized design with three replications. The abalone, with an initial average shell length of 27.26 ± 0.63 mm and weight of 3.27 ± 0.07 g, were reared in baskets (3 L) placed in a 60 L tank RAS for nine weeks. The results showed that the lowest production performance was observed at 0.4 L min −1 , while the highest production performance occurred at 1.6 L min −1. Based on the production performance and physiological responses, it was concluded that an aeration rate of 1.6 L min-1 and DO saturation levels of 74.88-92.75% appeared beneficial for enhancing H. squamata juvenile production in RAS. ARTICLE HISTORY
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The Indonesian abalone industry has been experiencing growth in recent years and holds significant potential for further expansion. This paper provides a comprehensive review of the current state of the abalone industry in Indonesia, including production processes, markets, and trade, as well as the challenges and opportunities faced by the industry. The study found that the growth of the Indonesian abalone industry is driven by both the domestic market and the increasing demand for Indonesian abalone in international markets. Despite these opportunities, the industry faces various challenges, such as illegal fishing practices, intense competition, and fluctuating prices. The Indonesian government has implemented regulations to promote sustainable harvest and trade practices to address these challenges. The industry is focused on producing high-quality abalone to maintain its competitive position in the global market. The Indonesian abalone industry needs to overcome these challenges To sustain its growth in the future, expand its market reach through international trade, and continuously produce high-quality products. This review provides valuable insights into the Indonesian abalone industry and highlights potential future directions for growth. The findings of this study could be useful for industry players, policymakers, and researchers interested in the development of the Indonesian abalone industry.
In the three-dimensional culture model, the breeding basket of the culture area is symmetrical and it is important to control the dissolved oxygen in the symmetrical region to improve the culture efficiency. Practical engineering issues, such as the influence of flow rate, pH, water temperature, and biological oxygen consumption on the dissolved oxygen content in the circulating water culture system, must be considered along with the presence of modeling errors in the control model. The authors propose an adaptive anti-disturbance control strategy for dissolved oxygen that combines nonlinear disturbance observation with an adaptive sliding model control. Initially, a dynamic model for controlling dissolved oxygen in a recirculating water aquaculture system was developed. The model considers external disturbances like artificial oxygenation, abrupt changes in system flow, and variations in culture oxygen consumption. Secondly, to enhance the robustness and accuracy of controlling dissolved oxygen concentration, the paper introduces a nonlinear adaptive disturbance observer for real-time estimation and observation of external disturbances and system uncertainties. This is accompanied by a sliding-mode control-based adaptive anti-disturbance strategy. Lastly, the simulation results demonstrate that the control strategy proposed in this paper shows resistance to system uncertainties and unknown external disturbances. Furthermore, it reduces the model accuracy requirements for the controller and proves to be suitable for accurately controlling dissolved oxygen in circulating water systems.
Eutrophication in aquaculture areas concurrently leads to a high incidence of dissolved oxygen deficiency and toxic algal blooms. The combined effects of hypoxia and typical toxic algae on cultured organisms should be given sufficient consideration. Abalone breeding in China has greatly suffered from hypoxia and toxic Karenia mikimotoi blooms for many years. In this study, the individual and combined effects of the toxic dinoflagellate, K. mikimotoi, and hypoxia on juvenile abalone were determined based on abalone survival and oxidative stress indicators in their gills, hepatopancreas and hemolymph. The results showed that at a density of 10⁶ to 3×10⁷ cells/L, K. mikimotoi alone had a negligible influence on the survival of juvenile abalone under sufficient dissolved oxygen (DO) conditions. The 24 h-half lethal concentration (LC50) of DO alone for juvenile abalone was 0.75 mg/L in seawater. When K. mikimotoi was added at a density of 3×10⁶ cells/L, the 24 h-LC50 of DO for juvenile abalone significantly increased to 2.59 mg/L, indicating obvious synergistic effects. The individual effects of hypoxia or K. mikimotoi on the oxidative stress indicators were limited, and only the superoxide dismutase (SOD) activity in the abalone gills significantly decreased under K. mikimotoi stress. However, the combined stress of hypoxia and K. mikimotoi led to significant changes in the antioxidant indicators in all tested tissues. The SOD activity in gills and hepatopancreas decreased, while the SOD and catalase (CAT) activity and malondialdehyde (MDA) content in the hemolymph increased due to the combined stress of hypoxia and K. mikimotoi. These results illustrated that the synergistic effects of hypoxia and K. mikimotoi caused serious oxidative damage in abalone and that the hemolymph exhibited greater sensitivity than did the gills and hepatopancreas. Further investigation found that K. mikimotoi increased the oxygen consumption rate in abalone and that hypoxia enhanced the hemolytic toxicity of K. mikimotoi. These results revealed that hypoxia and typical toxic algae cause synergistic harm to cultured organisms, which is expected to provide a new understanding of the destructive mechanisms of typical toxic algal blooms in aquacultural areas.
Aeration becomes an essential aspect of biofilter performance to reduce ammonia nitrogen in the Recirculating Aquaculture System (RAS). Efficient aeration introduces air into water media and offers an aerobic environment in the biofilter for microbial degradation of organic matter and ammonia nitrogen. The efficiency of the bubble aeration depends on the size of the bubbles; these include coarse bubble, microbubble, fine bubble, and ultrafine bubble or nanobubble. This review highlights an overview of bubble aeration features in a biofilter to reduce ammonia nitrogen. Moreover, key aspects responsible for the ammonia nitrogen removal efficiencies, such as oxygen transfer, microbial community, and biofilm thickness, are evaluated in this review. In conclusion, the bubble size of aeration affects the microbial community of nitrifying bacteria, consequently determining the growth and thickness of biofilm to improve ammonia removal efficiency. It is emphasized that fine bubble and nanobubble aeration have very positive prospects on improving biofilter performance, though they are currently not widely used in RAS.
Abalone species are economically important shellfish in China's aquaculture industry. In 2020, China's abalone aquaculture production was 203,500 tonnes, accounting for nearly 90% of total global production. However, many problems have accompanied the rapid development of this industry, including a reduction in near‐shore space suitable for culture and the risk of exposure of farms to natural disasters such as typhoons and red tides. In addition, high temperatures and low oxygen levels resulting from global climate change are causing increased abalone mortality in summer. In this review, the culture patterns and characteristics used in different countries are compared with respect to larvae nurseries, intermediate juvenile culture and the grow‐out phase. Next, the transitions and challenges in China's abalone culture industry over the past 60 years are summarized. Finally, a coordinated land‐sea program for reducing solid waste emissions into the water and increasing carbon sinks is suggested based on the ‘Carbon Neutrality’ theory. Under the framework of the program, new facilities, technologies and models should be created to achieve increased mechanization and a greater understanding of the abalone aquaculture industry as soon as possible. This review provides references and data to support the scientific planning and mapping of China's abalone culture industry as well as the transition of China's perceived identity from a major fishery country to a strong fishery power with an awareness of environmental protection and resource use.
Supersaturation of dissolved oxygen (DO) and total dissolved gas (TDG) is generated by high dam discharge, excess oxygen production in photosynthesis and increasing temperature in water, which may directly lead to fish suffering from ‘gas bubble disease’ or death. In this paper, under a series of experimental aeration conditions in standing water, it was concluded that aeration had a positively promoting effect on releases of supersaturated DO and TDG, while aeration aperture and aeration depth had inhibitory effects on them. For single factor analysis, aeration had the greatest effect on the release of DO and TDG, the second effect on DO was that of aeration depth and the smallest effect was that of aeration aperture, but the second effect on TDG was that of aeration aperture and the smallest effect was that of aeration depth. Most importantly, the release coefficient of DO was greater than that of TDG, and a quantitative relationship between the release coefficient of DO and TDG and aeration conditions, respectively, was established. An exponential function relationship of the release coefficients of DO and TDG was also established. The results of the research have important guiding significance and theoretical value for reducing the harm caused by supersaturated DO and TDG.
HIGHLIGHTS
The relationships between dissolved oxygen (DO) and total dissolved gas (TDG) and aeration, aeration depth and aeration aperture were established respectively.;
A quantitative relationship between release coefficient (DO/TDG) and aeration conditions was established.;
The root mean square error and the absolute average error were used for error analysis to judge the applicability of the equation. These equations were within 10%.;
The relationship between dissolved oxygen (DO) and total dissolved gas (TDG) was established.;
Microbubble aeration has been recognized as a tool to improve dissolved oxygen and fish culture performance in limited water aquaculture. This research aims to investigate the effect of microbubble aeration on increasing dissolved oxygen, fish culture performance, and stress resistance of red tilapia. The study used 3 treatments of aerations namely microbubble, blower, and without aeration with 3 replicates each. Red tilapia weighing 115.27±3.93 g were stocked in a plastic tank of 800 L water volume at density 50 individual/tank and cultured for 50 days in a recirculating aquaculture system (RAS). Dissolved oxygen, fish culture performance, and stress resistance were evaluated. Dissolved oxygen was monitored daily. In the middle of the research period, a stress test was performed using different salinity at 12 and 24 ppt. Statistical analysis was subjected to water quality, fish culture performance, and stressed resistance. The microbubble aeration was able to stabilize DO level on 4.28 mg/L until the end of the experiment and suppressed the CO2 and ammonia content. Fish biomass was higher in microbubble treatment, with a lower FCR value, lower stress level indicating fish in good health and promoting good culture performance. HIGHLIGHTS The critical parameter of water quality in aquaculture is dissolved oxygen (DO) and to increase its content is by aeration A nobel microbubble aeration was able to increase DO level higher than blower aeration and stabilize DO at requirement level until the end of the fish culture The strong relationship of DO with fish hematology parameters those more stable that indicate a lower stress level Stable physiological conditions and low stress of fish implied that the cultivated fish is in good health and good performance by microbubble aeration GRAPHICAL ABSTRACT
Dissolved Oxygen (DO) is one of the most important factors for aquatic animals as especially for those who derive dissolved oxygen from the water. DO levels indicate the quality of water. Many biotic and abiotic factors may influence DO concentration like mixing of different water bodies, upwelling, atmospheric exchange, respiration, photosynthesis, ice cover, pollution and some physical factors like salinity and temperature. The fluctuations in DO levels in water affect fish physiology. In this review, we will focus on the impact of DO on freshwater fish-physiology. A detailed literature survey is given based on DO and freshwater fish swimming, feeding, disease management, survival, respiration, metabolism, growth, reproduction, health parameters, immunity and stress of freshwater fishes.
Abalone adalah salah satu siput laut yang memiliki nilai ekonomi tinggi dan memiliki keunggulan karena kandungan protein tinggi mencapai 71,99%, kandungan lemak 3,24% dan dapat digunakan sebagai obat. Tingginya permintaan abalone menyebabkan peningkatan pengambilan langsung di alam dan berisiko pada kelangkaan abalone di perairan. Salah satu cara untuk mengatasi hal tersebut adalah melakukan budidaya abalone dengan sistem monokultur. Salah satu teknologi yang diaplikasikan adalah budidaya abalone adalah dengan menggunakan sistem recirculating aquaculture system (RAS) yaitu mengolah air yang telah digunakan agar dapat dimanfaatkan kembali untuk kegiatan budidaya. Tujuan penelitian ini adalah untuk menganalisis parameter kualitas air, pertumbuhan panjang dan berat serta kelulushidupan pada pemeliharaan benih abalon (Haliotis squamata) dengan menggunakan sistem RAS. Penelitian dilaksanakan pada bulan Juni – September 2020 di Balai Induk Udang dan Kekerangan, Karangasem, Bali. Penelitian menggunakan metode purposive sampling. Parameter kualitas air yang diukur meliputu nitrit, ammonia, TSS , pH, suhu, DO, dan salinitas. Hasil pengukuran kualitas air menunjukkan nilai nitrit berkisar 0 – 0,338 mg/L, ammonia 0 – 0,09 mg/L, TSS 0 – 15 mg/L, pH 7 – 8, suhu 26 – 28 oC, DO 4,3 – 7,07 mg/L, dan salinitas 31 – 38 ppt. Nilai tersebut masih dalam kisaran optimal untuk pemeliharaan abalone. Pertumbuhan panjang dan berat mutlak benih abalone selama penelitian masing-masing sebesar 25,17 mm/ekor dan 9,15 gr/ekor, dan nilai kelulushidupan 99,5 % selama 100 hari periode kultur.
Aerobic metabolism generates 15-20 times more energy (ATP) than anaerobic metabolism , which is crucial in maintaining energy budgets in animals, fueling metabolism, activity, growth and reproduction. For ectothermic water-breathers such as fishes, low dissolved oxygen may limit oxygen uptake and hence aerobic metabolism. Here, we assess, within a phylogenetic context, how abiotic and biotic drivers explain the variation in hypoxia tolerance observed in fishes. To do so, we assembled a database of hypoxia tolerance, measured as critical oxygen tensions (P crit) for 195 fish species. Overall, we found that hypoxia tolerance has a clear phylogenetic signal and is further modulated by temperature, body mass, cell size, salinity and metabolic rate. Marine fishes were more susceptible to hypoxia than freshwater fishes. This pattern is consistent with greater fluctuations in oxygen and temperature in freshwater habitats. Fishes with higher oxygen requirements (e.g. a high metabolic rate relative to body mass) also were more susceptible to hypoxia. We also found evidence that hypoxia and warming can act synergistically, as hypoxia tolerance was generally lower in warmer waters. However, we found significant interactions between temperature and the body and cell size of a fish. Constraints in oxygen uptake related to cellular surface area to volume ratios and effects of viscosity on the thickness of the boundary layers enveloping the gills could explain these thermal dependencies. The lower hypoxia tolerance in warmer waters was particularly pronounced for fishes with larger bodies and larger cell sizes. Previous studies have found a wide diversity in the direction and strength of relationships between P crit and body mass. By including interactions with temperature, our study may help resolve these divergent findings, explaining the size dependency of hypoxia tolerance in fish.
Pond aeration systems have been developed to sustain vast fish and invertebrate biomass duringthe past decade. These aeration systems are alterations of standard wastewater aeration systems. Aerationperformancetesting has been significant in selecting design features to provide cost-effective yet well-organizedaquaculture pond aerators. Aerators enhance the oxygen requirement for fish growth, and it iscrucially important in the intensive pond stocked with high densities. Dissolved oxygen concentrations havebeen linked to the water quality of the pond, Fish Growth and Survival, Reproduction, Feed utilization andmicroorganisms. Paddlewheel aerators and propeller-aspirator-pumps are probably most widely used.Aerators usually are placed in ponds to provide maximum air circulation in water. This article summarisesthe importance of mechanical aeration of aquaculture ponds for fish farmers.
Abalon memiliki cita rasa yang khas, mengandung 71,99% protein; 3,2% lemak; 5,6% serat kasar; dan 0,6% air. Harga jual di pasar domestik berkisar antara Rp 250.000-Rp 600.000 per kg tergantung ukuran dan di pasar internasional berkisar antara USD 22-USD 66 per kg tergantung kualitas dan jenisnya. Kegiatan pembenihan dimulai dengan pemeliharaan induk sampai gonad matang. Induk ditempatkan di dalam peti plastik dengan kepadatan 40-50 ekor/unit dan diberi pakan makroalga. Gonad induk yang telah siap dipijahkan berkembang dan menutupi organ hepatopankreas lebih dari 50%, dan pemijahan dilakukan di wadah pemijahan. Pemeliharaan larva dilakukan di dalam wadah yang sebelumnya telah dikultur diatom bentik sebagai pakan larva. Abalon berukuran 1-2 cm dipanen dan dipindahkan ke wadah pemeliharaan benih. Pemeliharaan benih dilakukan selama 2-3 bulan dan menghasilkan benih abalon yang siap dijual dengan ukuran 3cm. Kegiatan pembenihan menghasilkan FR 60%, HR 85%, dan SR 0,1-1%. Pengemasan benih dilakukan melalui tiga tahap, yaitu kantong jaring dengan kerapatan 75-100 ekor/kantong, kantong plastik berisi 20 kantong jaring/kantong plastik, dan boks styrofoam berisi 1 plastik/boks styrofoam.
The availability of oxygen and the minimum amount of ammonia in the water media are crucial in catfish larvae hatchery performance. The condition with a balanced amount of required oxygen and the presence of ammonia resulting from the feces of striped catfish larvae is essential to maintain the health of the aquaculture media. This study aims to remove ammonia by introducing fine bubbles (FBs) into recirculating aquaculture media and investigating reserved dissolved oxygen inside the bubbles in the media. The water media for the striped catfish larvae hatchery was designed and set up with three containers in a recirculating system. Also, a separate container was utilized as bubble storage connected to FBs generator. The water treatment was conducted in three different scenarios using air and pure oxygen as the FBs generator sources. The generated FBs were investigated in terms of their size and zeta potential concerning the dissolved oxygen (DO). The media’s DO was measured using the titration method and digital DO meter. The difference in DO concentration received from titration and DO meter define as potential reserved oxygen. Furthermore, the removal of synthetic effluent (ammonia, NH 4 Cl) and effluent in the media with FBs resources were investigated and tested at a different duration of FBs applications. The results showed that bubbles size was 518.5 – 607.6 nm independent of gas resource, either pure oxygen or air. However, the gas resources affected the zeta potential value of suspended bubbles, air (-11.5 to -16.7 mV), and pure oxygen (-21.4 to -25.2 mV). When pure oxygen was used as a gas resource, the media reach the oxygen supersaturation DO condition (25.39 ppm) within 45 minutes with reserve oxygen potential (ROP) of 2.95 ppm. Thus, this condition allowed the synthetic effluent removal of 83.33% and effluent removal of 39.93%. It is emphasized that the ammonia removal due to the presence of reactive oxygen species when the FBs collapsed and the information of ROP due to FBs application is important to preserve the fitness of aquaculture media for catfish larvae hatchery.
Ocean warming is affecting marine ectothermic herbivores as well as the macroalgal species they consume and this has the potential to alter their trophic interaction. However, it is currently still unknown how these two important components of benthic food webs will react to a warming environment. Consumption rates of grazers change with increasing temperatures, but it is unclear whether this is also true for feeding preferences. In this study, multiple-choice feeding assays with the tropical abalone Haliotis squamata from Western Indonesia were conducted in August 2018. After brief acclimation of either the grazer or the macroalgae to moderately elevated water temperatures (maximum 2 °C above the long-term average) in the laboratory, three species of living macroalgae were simultaneously offered to the abalone in feeding assays. Consumption rates of H. squamata were lower under elevated water temperatures, while its feeding preference switched: At 27 °C (2 °C below long-term average), abalone preferred non-acclimated Gracilaria salicornia , but switched to non-acclimated Amphiroa spp. at 31 °C. Interestingly, no such switch in preference occurred when the macroalgae, but not the grazers were acclimated. This indicates that the grazer will presumably be the driver of this potential change in interactions between H. squamata and its macroalgal food. Ocean warming may result in changes in the structure of benthic communities, mediated by changes in the feeding behaviour of herbivorous invertebrates.
Information about abalone growth is necessary to overcome the abalone culture sustainability. Water quality parameters are aspects that need to be reviewed, one of which is the calcium level in the water. The aim of this study was to determine the optimal calcium dose in recirculation system for abalone (Haliotis squamata) growth. The study was conducted with an experimental method with four treatments (calcium oxide with doses of 0, 15, 30, 45 mg/L) and three times replications. Abalone with 2.3 g body weight, 2.3 cm shell length, and 1.2 cm shell width was reared for 60 days in recirculation system and fed with Gracilaria verrucosa. The results showed that the best abalone treatment medium with the addition of calcium oxide to increase the abalone seed production was 15 mg/L CaO with 100% survival rate, 31.57±2.82% feed efficiency, and 0.56±0.06%/day specific growth rate.
Keywords: Abalone, calcium, organ composition, production, recirculation
ABSTRAK
Informasi tentang pertumbuhan abalon diperlukan untuk mengatasi keberlanjutan budidaya abalon. Parameter kualitas air merupakan aspek yang perlu ditinjau. Kadar kalsium dalam air menjadi salah satu aspek yang dapat ditinjau.Tujuan dari penelitian ini adalah menentukan dosis kalsium optimal melalui sistem resirkulasi untuk pertumbuhan abalon Haliotis squamata. Penelitian ini dilakukan dengan metode eksperimental dengan empat perlakuan 3 ulangan penambahan CaO dengan dosis 0, 15, 30, dan 45 mg/L. Secara singkat, abalon dengan bobot badan 2,3 g, panjang cangkang 2,3 cm dan lebar cangkang 1,2 cm dipelihara selama 60 hari dengan sistem resirkulasi dan diberi makan dengan Gracilaria verrucosa. Hasil penelitian menunjukkan bahwa media perlakuan abalon dengan penambahan kalsium oksida terbaik untuk meningkatkan produksi abalon adalah CaO 15 mg/L dengan tingkat kelangsungan hidup 100%, efisiensi pakan 31,57 ± 2,82 %, dan laju pertumbuhan spesifik harian 0.56 ± 0.06%/hari.
Kata kunci: Abalon, kalsium, komposisi organ, produksi, resirkulasi
Abalone has an economic value in the world. The larval rearing technique of abalone has produced successfully at Gondol Research and Development Institute for Mariculture, Bali, Indonesia. However, the grow-out of abalone has not well documented yet. The purpose of this experiment is to examine the shelter shape in relation to growth and survival for abalone ( Haliotis squamata ) grow-out culture in the tidal area. The shelter made from PVC piping. The shape of shelter as a treatment of this experiment was A) round; B) square and; C) without shelter. The data of growth and survival rate were analyzed using analysis of variance. The result showed that the shelter for the grow-out of abalone was significantly affected growth in terms of shell length and wet weight (P<0.05) while the survival did not influence (P>0.05). It seems that the shelter was correlated with the feeding behavior of abalone had resulted in different for their growing. The water quality such as salinity, dissolved oxygen, water temperature, and water current was within the optimal range for abalone. We found that round shelter shape is the best for grow-out abalone at the tidal area.
Nitrogen in pond sediments is a major water quality concern and can impact the productivity of aquaculture. Dissolved oxygen is an important factor for improving water quality and boosting fish growth in aquaculture ponds, and plays an important role in the conversion of ammonium-nitrogen (NH4+-N) to nitrite-nitrogen (NO2--N) and eventually nitrate-nitrogen (NO3--N). A central goal of the study was to identify the best aeration method and strategy for improving water quality in aquaculture ponds. We conducted an experiment with six tanks, each with a different aeration mode to simulate the behavior of aquaculture ponds. The results show that a 36 hr aeration interval (Tc = 36 hr: 36 hr) and no aeration resulted in high concentrations of NH4+-N in the water column. Using a 12 hr interval time (Tc = 12 hr: 12 hr) resulted in higher NO2--N and NO3--N concentrations than any other aeration mode. Results from an 8 hr interval time (Tc = 8 hr: 8 hr) and 24 hr interval time (Tc = 24 hr: 24 hr) were comparable with those of continuous aeration, and had the benefit of being in use for only half of the time, consequently reducing energy consumption.
Abalone (Haliotis squamata) is one of the fisheries commodities that have high economic value. This study was conducted to investigate contamination of Escherichia coli and coliform in Abalone cultivation ponds in the Musi Village area, Buleleng Regency, Bali. An experiment was carried out by taking water samples in the abalone pond every week for one month. The results showed that there was no difference between the total number of Escherichia coli and coliform. Water samples that were positive for coliform in the determination test had no differences in each sample with total coliform values (Colonies / 100mL) of 4, 3, 7 and 9 (MPN / 100mL) respectively. While the total number of Escherichia coli is shown after being grown in EMBA selective media which are 4, 3, 7, 4 (MPN / 100mL) respectively. Meanwhile, when compared with the number referenced from the Decree of the State Minister of Environment Number 51 of 2004 concerning Sea Water Quality Standards, the quality of seawater for aquatic cultivation in this study is still classified as Safe (<1000 MPN / 100mL).
Keyword : Abalone, Haliotis squamata, Eschericia coli, coliform, Bali
Gaseous oxygen is essential for all aerobic animals, without which mitochondrial respiration and oxidative phosphorylation cannot take place. It is not, however, regarded as a “nutrient” by nutritionists and does not feature as such within the discipline of nutritional science. This is primarily a consequence of the route by which O2 enters the body, which is via the nose and lungs in terrestrial animals as opposed to the mouth and gastrointestinal tract for what are customarily considered as nutrients. It is argued that the route of entry should not be the critical factor in defining whether a substance is, or is not, a nutrient. Indeed, O2 unambiguously meets the standard dictionary definitions of a nutrient, such as “a substance that provides nourishment for the maintenance of life and for growth” (Oxford English Dictionary). O2 is generally available in abundance, but deficiency occurs at high altitude and during deep sea dives, as well as in lung diseases. These impact on the provision at a whole-body level, but a low pO2 is characteristic of specific tissues includings the retina and brain, while deficiency, or overt hypoxia, is evident in certain conditions such as ischaemic disease and in tumours - and in white adipose tissue in obesity. Hypoxia results in a switch from oxidative metabolism to increased glucose utilisation through anaerobic glycolysis, and there are extensive changes in the expression of multiple genes in O2-deficient cells. These changes are driven by hypoxia-sensitive transcription factors, particularly hypoxia-inducible factor-1 (HIF-1). O2 deficiency at a whole-body level can be treated by therapy or supplementation, but O2 is also toxic through the generation of reactive oxygen species. It is concluded that O2 is a critical, but overlooked, nutrient which should be considered as part of the landscape of nutritional science.
Worldwide, there are approximately 100 Haliotis species, more commonly known
as abalone or ‘Paua’ in New Zealand, ‘Venus’s-ears’ in Greece, ‘Awabi’ in Japan,
‘Perlemoen’ in South Africa and ‘Ormers’ in Europe. Regardless of what they are
called in any part of the world, a high monetary value is coupled to this animal,
because it is largely considered a seafood delicacy. Subsequently, a great deal of
research primarily focused on improving the health and growth rates of abalone
were carried out to maximise productivity of the commercial farming efforts in
various countries. In this review, we comprehensively describe the most recent
available scientific literature on abalone biology, and those aspects related to the
growth of this organism; more specifically, those factors related to the uptake and
breakdown of metabolic products which ensures long-term growth. We subsequently
discuss this in terms of basic animal design, farming outcomes, feeding,
cellular growth mechanisms and the unique metabolic processes that exist in these
species. Using this information and the knowledge of the metabolic processes in
other organisms, we additionally make a number of new hypotheses regarding
how these metabolic processes may function in terms of abalone growth. Based
on the information presented in this review, we also identify major research
opportunities and gaps in the existing knowledge of abalone metabolism, which
when elucidated may not only serve the purpose of better understanding these
organisms growth but also could potentially lead to increased productivity of the
abalone commercial farming sector.
Exposure of nearshore animals to hypoxic, low-pH waters upwelled from below
the continental shelf and advected near the coast may be stressful to marine
organisms and lead to impaired physiological performance. We mimicked
upwelling conditions in the laboratory and tested the effect of fluctuating
exposure to water with low-pH and/or low-oxygen levels on the mortality and
growth of juvenile red abalone (Haliotis rufescens, shell length 5–10 mm).
Mortality rates of juvenile abalone exposed to low-pH (7.5, total scale) and low-O2
(40% saturation, mg L−1) conditions for periods of 3 to 6 h
every 3–5 days over 2 weeks did not differ from those exposed to control
conditions (O2: 100% saturation, 12 mg L−1; pH 8.0). However,
when exposure was extended to 24 h, twice over a 15-day period, juveniles
experienced 5–20% higher mortality in the low-oxygen treatments compared
to control conditions. Growth rates were reduced significantly when
juveniles were exposed to low-oxygen and low-pH treatments. Furthermore,
individual variation of growth rate increased when juveniles were exposed
simultaneously to low-pH and low-O2 conditions. These results indicate
that prolonged exposure to low-oxygen levels is detrimental for the survival
of red abalone, whereas pH is a crucial factor for their growth. However,
the high individual variation in growth rate under low levels of both pH and
oxygen suggests that cryptic phenotypic plasticity may promote resistance to
prolonged upwelling conditions by a portion of the population.
The aim was to analyze the amino acid and fatty acid of abalone Haliotis squamata cultured in different aquaculture systems. The percentage of total amino acid of abalone cultured in laboratory, floating cage, and longline system valued 11.02%, 9.53% and 8.24%. respectively. Abalone contained 14 saturated fatty acids and 16 unsaturated fatty acids. The saturated fatty acids of abalone were dominated by palmitenoic acid (C16:0) and steraenoic acid (C18:0). The high percentage of unsaturated fatty acids in abalone were oleat acid (C18:1n9), linolenic acid (C18:3n3), arachidonoic acid (C20:4n6) and eicosapentaenoic acid/EPA (C20:5n3).
The culture of abalone is a growth industry in Australia that primarily utilises terrestrial crops to produce formulated pellet feeds. The use of cultivated macroalgae in place of such feeds could provide for better environmental, nutritional and/or economic outcomes for this industry. However, direct comparison trials using macroalgae and formulated crop feeds are rare, and it is therefore difficult to ascertain the benefits and costs of each feed type. This study compares the benefits to growth and performance of the cultivated hybrid abalone cross (Haliotis rubra 1814 Leach and Haliotis laevigata 1808 Donovan) which was fed one of eight dietary treatments, including two commercially formulated pellet feeds and six mixed macroalgae dietary treatments. Macroalgae dietary treatments comprised the three macroalgae species Grateloupia turuturu Yamada, Ulva australis Areschoug and/or Ulva laetevirens Areschoug. Four replicate tubs, each containing 40 juvenile abalone (10–15 mm), were used to test each dietary treatment over a 12-week period. Macroalgae dietary treatments provided for significantly higher specific growth rates of abalone compared to formulated feeds, by orders of magnitude, for both length (>0.2 % compared to <0.1 % day−1, F
7, 31 = 22.3, p < 0.0001) and weight (from <0.4 to >0.8 % day−1, F
7, 31 = 24.4, p < 0.0001). In addition, abalone health and condition increased, and the proximate composition of abalone tissue had a higher carbohydrate/protein ratio, higher ash content and lower lipid content. These findings suggest that the juvenile abalone may benefit from macroalgae diets in comparison to two formulated feeds as a result of optimal proximate composition of the algae biomass and improved condition of the abalone.
The effect of various macroalgal diets on the growth of grow-out (>20 mm shell length) South African abalone Haliotis midae was investigated on a commercial abalone farm. The experiment consisted of four treatments: fresh kelp blades (Ecklonia maxima (Osbeck) Papenfuss) (c. 10% protein); farmed, protein-enriched Ulva lactuca Linnaeus (c. 26% protein) grown in aquaculture effluent; wild U. lactuca (c. 20% protein); and a combination diet of kelp blades + farmed U. lactuca. Abalone grew best on the combination diet (0.423 ± 0.02% weight d−1 SGR [specific growth rate]; 59.593 ± 0.02 −m d−1 DISL [daily increment in shell length]; 1.093 final CF [condition factor]) followed by the kelp only diet (0.367 ± 0.02% weight d−1 SGR; 53.148 ± 0.02 −m d−1 DISL; 1.047 final CF), then the farmed, protein-enriched U. lactuca only diet (0.290 ± 0.02% weight d−1 SGR; 42.988 ± 0.03 um d”1 DISL; 1.013 final CF) that in turn outperformed the wild U. lactuca only diet (-0.079 ± 0.01% weight d−1 SGR; 3.745 ± 0.02 −m d”−1 DISL; 0.812 final CF). The results suggest that protein alone could not have accounted for the differences produced by the varieties of U. lactuca and that the gross energy content is probably important.
To quantify the effects of serial-use of water on abalone growth and feed conversion, this study describes water quality in a serial-use raceway with seven passes. A flow index of 7.2–9.0 L h−1 kg−1 was estimated as the minimum value at which to grow 60–70 mm Haliotis midae, as weight gain (analysis of variance; F6, 14=13.9, P<0.0001) and feed conversion ratio (Kruskal–Wallis test; H6, 21=16.3, P=0.012) were significantly reduced at lower values. pH and dissolved oxygen concentration were positively correlated with the flow index (pH, r2=0.99; P<0.001; dissolved oxygen, r2=0.99; P<0.001), while free ammonia nitrogen (FAN) and nitrite were negatively correlated with the flow index (FAN, r2=0.99, P<0.001; Nitrite, r2=0.93, P<0.001). The concentration of nitrite increased throughout the experiment and may reflect the colonization of Nitrosomonas bacteria as water re-use increased. Based on comparisons with growth and toxicity tests, it is suggested that low pH combined with growth-limiting levels of FAN were the first variables limiting abalone growth in the serial-use raceway.
During winter months, a novel overwintering mode of transferring juvenile abalones to open seawaters in southern China rather than keeping them in closed land-based nursery systems in northern China is a popular practice. The initial size, stocking density and sorting are among the first considerations when establishing an abalone culture system. This study aimed to investigate the effects of these factors on the growth of juvenile Pacific abalone, Haliotis discus hannai Ino, during overwintering. Juvenile abalones were reared in multi-tier basket form for overwintering in open seawaters in southern China for 106 days. The daily growth rates (DGRs) in the shell length of all experimental groups ranged from 67.08 to 135.75 μm day−1, while the specific growth rates (SGRs) were 0.2447–0.3259% day−1. Variance analysis indicated that both DGRs and SGRs in shell length were significantly affected by the initial body size and stocking density. Furthermore, the effects of stocking density on DGRs and SGRs varied with the initial size. However, sorting abalones according to their initial sizes may not be necessary in practice as sorting did not alter growth significantly at all densities in this study. Factors potentially affecting abalone growth such as genetic control and intraspecific competition were discussed.
The study investigated the growth performance of abalone from juvenile to marketable size in a commercial-scale recirculating
aquaculture system. The rearing system consisted of 12 raceways (4.0×0.8×0.6m) with a protein skimmer and a submerged
biofilter for juveniles and 10 raceways (6.6×1.3×0.6m) with a protein skimmer and a trickling biofilter for on-growing.
Sea mustard (Undaria pinnatifida) and kelp (Laminaria japonica) were fed to the abalone. The total weight of abalone in the recirculating aquaculture system at the juvenile stage increased
from 22.0kg (average shell length 24.5mm) to 75.5kg (average shell length 42.5mm) after 180days. Feed conversion ratios
increased slightly from 13.7 for the first 90days to 16.3 thereafter. The shell growth rate of juvenile abalone between 24.5mm
and 34.8mm was 3.4mm month−1, while for juveniles between 34.8mm and 42.5mm it was 2.6mm month−1. The total weight of abalone in the recirculating aquaculture system for the on-growing stage increased from 100.0kg (average
shell length 44.0mm) to 433.3kg (average shell length 72.7mm) after 570days. The feed conversion ratios for the first
173days, the next 320days, and the last 570days were 19.6, 22.1, and 24.8, respectively. The growth rate of the average
shell length during the on-growing period was 1.5mm month−1. Total ammonia nitrogen (TAN) concentrations were stabilized below 0.12mgl−1 in the juvenile recirculating system and 0.14mgl−1 in the on-growing recirculating system after conditioning of the biofilters.
The South African abalone cultivation industry has developed rapidly and is now the largest producer outside Asia. With a rapid decline in wild abalone fisheries, farming now dominates the abalone export market in South Africa. Kelp (Ecklonia maxima) constitutes the major feed for farmed abalone in South Africa, but this resource is now approaching limits of sustainable harvesting in kelp Concession Areas where abalone farms are concentrated. This paper gives an overview of the development of the South African abalone industry and analyses how abalone farming, natural kelp beds and seaweed harvesting are interlinked. It discusses options and constraints for expanding the abalone industry, focussing especially on abalone feed development to meet this growing demand.Kelp will continue to play an important role as feed and kelp areas previously not utilised may become cost-effective to harvest. There are many benefits from on-farm seaweed production and it will probably be a part of future expansion of the abalone industry. Abalone waste discharges are not at present regarded as a major concern and farming brings important employment opportunities to lower income groups in remote coastal communities and has positive spillover effects on the seaweed industry and abalone processing industry.
Abalone (Haliotis spp.) is a highly demanded product due to its quality. Although abalone production volume is not as high relative to other seafood products, it is highly valued; it amounted to nearly 2.6 billion dollars in 2017. Previously, global abalone production depended primarily on fisheries, but now days it relies mostly on aquaculture; today, over 95% of abalone production comes from aquaculture. Several factors govern the price of abalone in the international market, including production and export volumes, among others. Therefore, it is of interest to elucidate the factors that drive abalone supply and demand. We used exports and imports data of the major abalone producers to investigate the market behavior using non-parametric statistical analyses and historical and current abalone production data worldwide. Our findings confirm the existence of significant correlations between the various mechanisms governing the abalone demand, supply, and price. It was found that the supply behavior (catch-price) of Mexican and Australian abalone was adjusted to the bioeconomic model of the backward-bending supply curve for fisheries, due to overexploitation or the establishment of catch quotas.
Oxygen availability during different stages of biological nutrient removal (BNR) plays utmost critical role in all wastewater treatment techniques. Inadequate aeration control results in low treatment efficiencies and may lead to significantly higher costs. Hence, a strategically designed aeration scheme is very crucial. This study was carried out with the objective of maximising nitrogen and phosphorus removal from sewage by implementing an optimised aeration strategy. To achieve this, a 4-hour Anaerobic/Aerobic/Anoxic (AOA) cycle based on dissolved oxygen (DO) and oxidation-reduction potential (ORP) values was strategically designed, implemented and monitored in a 4.5 l laboratory-scale Sequencing Batch Reactor (SBR). On an average, feed waste consisted of 170 mg/l of biological oxygen demand (BOD), 228 mg/l of chemical oxygen demand (COD), 64 mg/l of total nitrogen (TN) and 33 mg/l of ortho-phosphate (PO43−). The average BOD, COD, TN and PO43− loading rates of 0.510, 0.684, 0.192 and 0.099 kg/(m3-d), respectively were applied to the reactor. During the 90-day operation of the SBR, it was observed that BOD, COD, TN and PO43− removal were achieved with 91%, 93%, 90% and 75% efficiencies, with removal rates of 0.477, 0.614, 0.173 and 0.075 kg/(m3-d), respectively. Also, the cycle study revealed that P removal occurred during the aerobic phase, while N removal occurred during the anoxic phase through denitrification. A mass balance analysis for N also revealed that denitrification and microbial uptake accounted for 59% and 41% of nitrogen removal, respectively. Study revealed that nutrient removal was achieved successfully while avoiding any unnecessary extended aeration costs. Such aeration strategy based on DO and ORP values could be deployed not only to optimise the aeration phase lengths, but could also be used for dynamic process control to manage fluctuations in influent characteristics and system conditions.
In any aquaculture plant maintaining dissolve oxygen (DO) level is essential for the better health and survival of the living organisms present in the water body specially fish. DO level can be maintained by aeration process. The general idea behind aeration is to bring the water into intimate contact with the air. Either the water may be discharged into free air or the air may be forced into water. Aeration process also removes light volatile organic compounds, dissolve gases and fix odor, taste etc. in case of drinking water. Some common Apparatus used includes: low cascades, multiple jet fountains throwing water to considerable heights, spray nozzles discharging above the surface of a reservoir, superimposed trays or shelves, submerged perforated pipes, and porous tubes and plates.There are two ways, standard oxygen transfer rate (SOTR) and standard aeration efficiency (SAE) of describing aerator performance. In selection of aerators for aeration in fish culture tank, durability and good standard aeration efficiency (SAE) value is too important moreover in case of aerators high standard oxygen transfer rate (SOTR) is important for the better growth of aquatic animals present in water. This article gives a review of different types of aerators used in aeration process based on various basis.
Recently, mass mortality of cultured Pacific oyster (Crassostrea gigas) has occurred frequently, which has aroused our attention to the stress tolerance of oyster. Hybridization is regarded as an effective way to produce genetic improvement in aquaculture, which can effectively introduce improved characteristics to the hybrids. In the present study, we evaluated the physiological and immune responses at different temperatures (16–36 °C) and salinities (15–35 psu) in two strains of C. gigas, a fast-growing strain “Haida No. 1” (HH) and an inbreeding line with orange shell color (OO), and their reciprocal hybrids HO (HH♀ × OO♂), OH (OO♀ × HH♂).
Oxygen consumption rate (OCR), ammonia-N excretion rate (AER), superoxide dismutase activity (SOD), catalase activity (CAT) and contents of malondialdehyde (MDA) were determined on day 10 of the temperature and salinity exposure. Results showed higher stress resistance ability of the hybrids than their parents against environment challenge. For physiological parameters, the OCR of OH strain increased in the experimental temperature range, while the maximum values of HO, HH and OO strains were 2.013, 2.193 and 1.994 mg g⁻¹ h⁻¹ respectively at 31 °C; OCR and AER of OH strain was significantly higher than that of the other strains at lower salinity (P < 0.05). For immune parameters, the overall SOD and CAT activity of hybrids were lower than that of the other strains under temperature treatments. Besides, the overall MDA content of OH strain was lowest at experimental temperature and salinity, and the other three strains' MDA level ranked as: OO > HH > HO. Overall, the results suggest that environment changes could significantly affect the physiological and immune status of oyster, and hybrids may be more resistant to environment stresses than their parents. This study provides physiological and immune evidences for interpreting the stress resistant heterosis in this oyster hybrid system, which could help us in a better understanding and utilization of heterosis in oyster aquaculture.
Modeling dissolved oxygen (DO) in running water represents a challenge due to complex interactions among various processes affecting its concentration and the intricacy of using process-based water quality models. In this study, a quantile regression forest (QRF) machine learning technique was used to develop data-driven models for predicting DO levels in three rivers that drain watersheds with distinctly different land use and land cover characteristics in different geographical regions. Water quality data, spanning 2007 to 2019, was used to develop and validate the models. Key DO drivers were first identified based on the variable importance index, and models were constructed for different combinations of the identified drivers as the input variables. Each model was calibrated for each input scenario using 80% of the data and validated by predicting the DO concentrations using the remaining 20% of the data. Excellent model performance was obtained with water temperature, pH, specific conductance, and chemical oxygen demand (COD) as input variables across the stations with water temperature and pH as the top predictors. The developed models outperformed multilayer perceptron neural network (MLPNN) and U.S. Environmental Protection Agency models in explaining data variance as well as giving lower errors in predictions. The commonality of the top-ranked predictors for the three geographically distant rivers suggests the possibility of building parsimonious models with a minimal number of predictors for in-stream DO predictions. These predictors are among the common physio-chemical water quality parameters of existing ambient water quality monitoring programs and are readily available for the model development.
In order to examine the effects of different stocking densities and culture methods on the growth, food intake and expression of related genes in Haliotis discus hannai ♀ × H. fulgens♂ hybrid abalones, juvenile abalones were placed into three treatment groups of different stocking densities (400, 600, 800 ind/m²) and cultured using two different methods, including suspension cages and bottom sowing. There were three replicates of each experimental group (stocking density and culture method) and the experiment lasted for 180 days. The results showed that the survival rate, specific growth rate of shell length and body weight, food intake and feed conversion efficiency of the abalones cultured in suspension cages were significantly lower than those in the bottom sown group. For abalones cultured by bottom sowing, there was no significant difference between the specific growth rate of shell length and body weight, feed conversion efficiency, α-amylase, cellulase activity and the expression levels of Hdlam on each sampling occasion for the 400 and 600 ind/m² treatments. However, these parameters were significantly higher in both the 400 and 600 ind/m² treatments compared with the 800 ind/m² treatment. When the stocking density was increased to 800 ind/m², the food intake and the expression levels of Hdaly, Hdcel, Hdamyl of the abalones cultured in both culture methods were significantly lower than the 400 and 600 ind/m² treatments. This indicates that even with sufficient food supply, some abalones were unable to capture food due to the constraints of the culture space and the feeding method used by abalones, resulting in reduced growth. The findings of this research suggest that the growth and food intake of abalones can be promoted and production can be improved at a stocking density of 600 ind/m².
Anthropogenically increased occurrence of hypoxic conditions in the aquatic environment, combined with climate change-induced temperature increase, is causing increased concern for aquaculture species. In this study, the survival of the Pacific abalone Haliotis discus hannai (DD) and its hybrid offspring (H. discus hannai ♀ × H. fulgens ♂, DF) were observed under 96 h hypoxia at both optimum temperature (20 °C) and high temperature (28 °C). The respiration rates (MO2) of DD and DF facing acute hypoxia at three temperatures (20 °C, 25 °C, and 28 °C) and progressive hypoxia at three different sizes (2 cm, 4 cm, and 6 cm) were compared. At 20 °C, there was no significant (p > .05) difference between median lethal concentrations (LC50) of DD and DF while considering all time intervals; however, at 28 °C, 96 h DO LC50 of DF (3.18 mg/L) was lower than that of DD (4.82 mg/L), indicating that DF displayed stronger hypoxia tolerance ability than DD at 28 °C. MO2 of DD and DF increased with rising temperature and larger sizes under acute and progressive hypoxia tests, while DF showed higher MO2 than DD, indicating its better plasticity of oxygen uptake. These results suggest that DD might be more vulnerable to a combination of thermal and hypoxia stress than DF, revealing that hybridization could be a useful way to improve stress-resistance for the abalone aquaculture industry.
In order to examine the effects of stocking density on growth, food intake, energy budget, and expression levels of related genes of the abalone Haliotis discus hannai Ino, specimens (mean ± standard error shell length: 36.25 ± 1.97 mm, weight: 6.88 ± 0.71 g) were cultured at four different stocking densities (600, 900, 1200, and 1500 ind/m²). Four replicates were set for each density, and the experimental period was 60 days. At the end of the experiment, the survival rate, shell length, and weight specific growth rate of abalones in the 600 and 900 ind/m² groups were significantly higher than in the 1200 and 1500 ind/m² groups (P < 0.05). The food conversion rate of abalones in the 900 ind/m² group significantly increased compared with the other groups (P < 0.05). The activity of hexokinase in the 1200 and 1500 ind/m² groups was significantly higher than that in 600 and 900 ind/m² groups (P < 0.05). The activity of pyruvate kinase in the 1500 ind/m² group showed no significant difference compared with the 900 and 1200 ind/m² groups (P > 0.05), but was significantly higher than that in the 600 ind/m² group (P < 0.05). In the 1200 and 1500 ind/m² groups, lactic dehydrogenase activity at Day 60 increased significantly compared with Day 30 (P < 0.05). In the 900 ind/m² group, the energy accumulated for the growth was significantly higher than that in the 1200, and 1500 ind/m² groups (P < 0.05), but there was no significant difference compared with the 600 ind/m² group (P > 0.05). As the stocking density increased, expression levels of Mn-superoxide dismutase, catalase, glutathione-s-transferase, thioredoxin peroxidase, and heat shock protein 70 in the 1500 ind/m² group at the end of the experiment were significantly higher than in the other groups (P < 0.05). At Day 30, the expression level of heat shock protein 90 in the 1200 ind/m² group showed no significant difference compared with the 1500 ind/m² group (P > 0.05), but it was significantly lower than that in the 1500 ind/m² group at the end of the experiment (P > 0.05). In the 1200 and 1500 ind/m² groups, the food availability was lower, levels of anaerobic metabolism increased, and more energy was required to resist oxidative damage; therefore, no energy was accumulated for growth. When the stocking density was 900 ind/m², the survival rate of abalones was the highest with fast growth, the density factor didn't cause oxidative stress to the organism, and more food-derived energy were accumulated and used for the growth of abalones. Considering aquaculture production output and business profitability, it would be more appropriate to control the stocking density at 900 ind/m² for abalones with a shell length of 3–4 cm.
Following the digestion and absorption of food from the digestive tract of fish or shrimp, nutrients become available to meet the metabolic needs of the animal. In the context of feed management some understanding of the nature of essential nutrients used in aquaculture feeds is important when selecting and using feeds of different types. There is extensive literature covering fish and shrimp nutrition and only an outline is included here (reviews are given in Cowey et al., 1985; Halver, 1989; Lovell, 1989; Wilson, 1991; Akiyama et al., 1992; Kaushik and Luquet, 1993; NRC, 1993; Cowey and Wilson, 1994).
In recent years, the total quantity of abalone produced on farms worldwide has increased significantly while abalone fisheries have declined. Fishery production was almost 20,000 metric tons (mt) in the 1970s but was only about 6,500 mt in 2015. Over the same period, farm production has increased from negligible quantities in the 1970s to 129,287 mt in 2015, the majority being produced in China and South Korea. Illegal exploitation, particularly in South Africa, Australia, and New Zealand, is still a major problem. Prices on the world market fell during the Global Financial Crisis, but now appear to be increasing again.
Tidal current survey as well as geochemical and benthic foraminiferal analyses of sediment cores were conducted in an abalone farm and a Zostera bed to understand the degree to which the abalone farm facilities installed along a channel in a shallow sea affect the benthic environment and ecology. In the abalone farm, Ammonia beccarii-Pseudoparrella naraensis-Elphidium somaense-Rosalina globularis-Trochammina hadai and P. naraensis-E. somaense-A. beccarii-T. hadai assemblages appeared owing to an increase in the total nitrogen content from the biodeposits. The Zostera bed consisted of A. beccarii-P. naraensis-Buccella frigida-T. hadai assemblage owing to the gradual expansion of a brackish shallow-water environment by the rapidly decreasing current speed, and it may have flourished. Moreover, the total sulfur, Zn, Cr, and Cu contents in the sediments decreased remarkably more than those of the pre-abalone farming did, caused by the vigorous activity of Zostera marina physiology.
A mathematical model was developed to predict the effects of wind speed, light, pH, Temperature, dissolved carbon dioxide and chemical oxygen demand (COD) on Dissolved Oxygen (DO) in fish ponds. The effects of organic feeds, aeration and fish activity were added to the model developed by Kayombo et al. for Waste Stabilization Ponds (Ecological Modeling 127(2000): 21-31) to reflect the situation in fish ponds. Model calibration and validation was done by use of average DO, pH, temperature, COD, CO2 and algae biomass data measured from RETCO fish ponds in Dar es Salaam; and light intensity data were adopted from Kayombo et al. (2000). Model results showed a linear relationship between simulated DO and measured DO in fish pond (r2 = 0. 87) for model calibration and (r2= 0.88) for model validation. Simulation results also showed a general decrease of DO with time in 13 days by 28% and 38% for first and second batch, respectively. Thus, the model developed in this study could be used to predict the DO dynamics in fish ponds. Based on the model results, successful cultivation of healthy fish may require that retention time for water in the fish pond be 10 days.
In aquaculture, the dissolved oxygen volume in water has a significant impact on fish growth and development, which should be monitored. In order to improve the monitoring results, the mathematical model of the dissolved oxygen monitoring system has been built. The PID controller has been designed with the Simulink software and its parameters have been optimized with the nonlinear control design module of the software. After the simulation analysis on the system, the system is stable. The optimized system has smaller overshoot and faster response, and gets a better control. The modeling and simulation of the dissolved oxygen monitoring system in aquaculture has laid an important basis on analysis of the system and has accumulated experiences for the practical application.
Pacific abalone (Haliotis discus hannai Ino) aquaculture is a thriving industry in China. This study describes a novel submerged cage culture system for abalone rearing in Fujian, South China. The cage consisted of five vertical slots that were oriented perpendicular to the flow of water. The slots were separated by six vertically connected plastic plates for abalone attachment and shelter at the bottom of the cage. Experiment 1 was designed to determine the appropriate stocking density at the start of the abalone sea‐based production cycle. Eight‐month‐old hatchery reared and size‐graded juveniles were transferred to the sea‐based culture system. For different stocking densities, shell length of juveniles obtained in this novel culture system on 2, 3.5 and 5 months, respectively, was compared with shell lengths obtained in a traditionally multi‐tier basket culture system. In Experiment 2, daily growth rates (DGRs) in shell length and biomass in terms of wet weight of 2‐year‐old abalones reared in cage and tiered basket culture systems were compared over a 6‐month period. Results of Experiment 1 showed that growth of abalone in the cage culture system is density‐dependent; the mean final shell length of juveniles obtained was 6.7–15.9% higher than in tiered baskets system even at the same initial stocking density. In Experiment 2, DGRs in shell length of 53.83–78.38 μm day−1 obtained in cage system were significantly higher than that in tiered baskets (P 0.01). And in terms of wet weight biomass, it was 1.48–3.01 times higher in the cage system compared with the traditional system. Abalone survival was more than 87.5% in both culture systems in both experiments. Advantages of the newly established cage culture system included better growth performance of the animals reared and potential improvement of rearing conditions, such as improved water flow velocity and dissolved oxygen.
When ectotherms are exposed to high temperatures, cellular oxygen demand increases. When oxygen demand exceeds oxygen availability, animals may experience functional hypoxia regardless of environmental oxygen levels.
In the current study, we aimed to assess if oxidative or thermal restrictions exist when winter-acclimated Haliotis midae juveniles are re-acclimated to temperatures within their thermal tolerance range, but with one temperature outside the average daily temperatures they would experience in winter. At each acclimation temperature (14, 16 and 19 °C), we also manipulated dissolved oxygen levels to obtain oxygen saturation levels of 82%, 98% and 126%.
Our results indicate growth restrictions and hypometabolism at all oxygen treatments at 19 °C. Efficiency of mitochondrial respiration, as indicated by an increase in cytochrome c oxidase subunits 1 and 2 (cox1 and cox2) transcript level, was improved at 19 °C, 98% oxygen. A change in substrate utilisation, from a glycogen/lipid-driven metabolism to almost exclusively protein-driven metabolism provided the fuel for more effective cellular respiration. A further decrease in metabolic rate at 19 °C, 126% oxygen, this time without an increase in cox1 and cox2 transcripts, may indicate some improvement in gas exchange, but without improvement in growth.
We propose that 19 °C is nearing a long-term limiting temperature for winter-acclimated SA abalone, and that animals survive this condition by re-allocating available energy to survival mechanisms instead of growth. This species, already threatened by over-harvesting, may be further threatened by increases in surface seawater temperatures.
Commercial abalone culture is carried out using flow-through systems with a high water volume exchange in Baja California, Mexico. The objective of this work was to compare the growth rate and survival of red abalone cultured in two systems. Flow through (daily water exchange rate of 800%) and recirculating systems consisted of a 250 L fibreglass tank and constant aeration, but biofiltration in the recirculating system was provided with a 28 L (1 ft3) bubble-washed bead filter. Water variables were measured either daily (dissolved oxygen, temperature, pH and salinity) or three times a week (total ammonia nitrogen, nitrate-nitrogen, nitrite-nitrogen and alkalinity). Shell length was measured every 2 weeks for 18 weeks. Only the alkalinity and pH were significantly different due to the addition of sodium bicarbonate to the recirculating system. Abalone growth rate was 26.1 +/- 15.96 mu m day-1 in the recirculating systems and 22.21 +/- 18.69 mu m day-1 in the flow-through systems. The final survival was 78.74% in the recirculating systems and 71.82% in the flow-through systems. Significant differences in the final size and survival of the abalones were found between systems (P < 0.05). Therefore, recirculating aquaculture systems is a feasible alternative for juvenile red abalone culture.
Oxygen consumption and ammonia excretion rates of three abalone species, Haliotis discus discus, H. gigantea, H. madaka and their hybrids were measured at 20 °C by incubating for 3 h under dark and light (N=9–13 for each species and hybrid). Animals were fasted before and during the experiment and measurements were made first under dark followed by light on the next day. The rates increased with the increase in body weight and were higher under light than dark. On average, H. discus discus had higher oxygen consumption (DD; dark=0.039, light=0.04 ml/g/h) than H. gigantea (G; D=0.033, L=0.036) and H. madaka (M; D=0.034, L=0.035); the hybrids had varied patterns with respect to their parental species [DD×M (D=0.032, L=0.038); M×DD (D=0.03, L=0.038); G×DD (D=0.035, L=0.04) and DD×G (D=0.03, L=0.034), mother first]. M (0.261, 0.298 μmol/g/h) had the highest ammonia excretion rate while G (0.162; 0.264) and DD (0.229; 0.232) had the lowest under dark and light, respectively. The hybrids had varied patterns in comparison with their parents (DD×M=0.247, 0.32;M×DD=0.177, 0.28; DD×G=0.249, 0.364 and G×DD=0.116, 0.155). The O/N ratios under both conditions in all species and hybrids indicated that they had carbohydrate dominated metabolism. Results demonstrated physiological variability among the species and hybrids indicating necessity of different strategies for their management and aquaculture.
Data collected from a single grow-out tank in an abalone farm in southern New Zealand has highlighted hygiene maintenance problems in the use of semi-closed water conditioning systems for the aquaculture of New Zealand black foot abalone Haliotis iris. The data shows that semi-closed systems can have high concentrations of un-ionized ammonia, which is harmful to the animals. In this paper an alternative open flow-through system is suggested where energy demand is limited by heat recovery at the grow-out tank outlet. Using temperature data collected over 1 year, and a previously obtained expression for standing losses, a simple energy model is presented for an open system with heat recovery. To compliment the energy model, a function has been established for abalone production with respect to the concentration of un-ionized ammonia and water temperature. The energy model and production function are combined to determine the impact of plant design and tank conditions on the economics of the operation for the southern New Zealand climate. It is demonstrated that temperature control is financially preferable to an open system with no temperature control, and estimates of optimum operating conditions are given. Copyright © 2004 John Wiley & Sons, Ltd.
Formulated abalone feeds used by the culture industry are believed to be unsuitable for use at elevated water temperatures (>20 °C). The aim of this study was to develop a feed that could safely be fed to abalone cultured at elevated water temperatures by optimizing dietary protein/energy levels. Abalone (54.90 ± 0.08 mm; 28.99 ± 0.16 g) were cultured at either 18, 22 or 24 °C, and fed diets containing graded levels of protein (18–26%) and energy (11.6–16.2 MJ kg−1). Abalone growth was temperature dependent, declining from 4.33 g month−1 at 18 °C to 0.77 g month−1 at 24 °C. Shell length and weight gain were independent of dietary protein, provided that the digestible energy content of the diet was not lower than 13.5 MJ kg−1. Dietary energy levels below 13.5MJ kg-1 resulted in significant reductions in shell growth, weight gain and increased mortality from 5% to 27%. Feed consumption of the 22% and 26% protein diets with 11.6 MJ kg−1 was significantly higher (0.53 ± 0.04 and 0.55 ± 0.04% bd. wt. day−1 respectively) compared with abalone fed the 16.2 MJ kg−1 diets at the same protein levels (combined mean of 0.45 ± 0.04% bd. wt. day−1) indicating that consumption was linked to energy requirement. The growth and mortality results suggest that abalone cultured at these temperatures have a dietary digestible energy requirement of at least 13.5 MJ kg−1.