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Process flow diagram of an individual experimental-scale RAS, illustrating direction of water flow and all water treatment unit processes, and with the five sampling locations for waterborne hormones indicated.
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Steroid hormones have been shown to accumulate in recirculation aquaculture system (RAS) water over time; however, their influence on the reproductive physiology of fish within RAS remains unknown. Whether ozonation impacts waterborne hormone levels in RAS has likewise not been fully evaluated. To this end, a controlled 3-month study was conducted...
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... replicated (n = 6) experimental RAS used in this study have previously been described in detail Good et al., 2011;Davidson et al., 2013); the components of an individual RAS are shown in Fig. 1. To summarize, each system consisted of a fluidized- sand biofilter, CO 2 stripping column, low-head oxygenator (LHO), cir- cular dual-drain culture tank (5.3 m 3 ), radial flow settler, microscreen drum filter (60 μm), heat exchanger, and a 1-HP centrifugal pump. The total RAS water volume was 9.5 m 3 ; water was recirculated at a ...
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... methodologies, and frequencies of testing are summarized in Table 1. To assess the effects of ozonation on waterborne hormones, 250 mL water samples were collected in triplicate in high density polyethylene bottles at the following locations in each RAS: i) makeup water, ii) pre-biofilter, iii) post-biofilter, iv) post-gas conditioning, and (Fig. 1), during two separate sampling events which took place during weeks 10 and 12 of the 12-week study period. A total of 180 water samples were collected (i.e., 90 samples from each sampling event). All water samples were frozen and stored on-site until overnight shipment to the University of Alabama for hor- mone ...
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... processes). Concentrations of 11- KT were significantly higher in post-gas conditioning water samples compared to post-biofilter samples (Fig. 2); however, this is likely the result of biofilter-bypassed water (relatively high in 11-KT concentra- tion) combining with the biofiltered water prior to the post-gas con- ditioning sampling location (Fig. 1). As was postulated in Good et al. (2014), the relative susceptibility of 11-KT to reduction through bio- filtration is likely related to its individual physicochemical properties, specifically its relatively low octanol-water partition coefficient (log K ow ). Log K ow is a measure of the tendency of an organic compound to adsorb to ...
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Accumulation of organic matter and particles generated from uneaten feed and faeces is one of the major challenges in recirculating aquaculture systems (RAS), in particular colloidal and dissolved fractions as these serve as bacterial substrate. Particles can potentially cause damage on the gills of the reared species and may reduce their resistanc...
High carbon dioxide (CO2) concentrations negatively impact fish, which makes data on its tolerance especially relevant for production systems that can accumulate CO2 such as recirculating aquaculture system (RAS). The current study evaluates the effect of CO2 on the growth performance, welfare, and health of Atlantic salmon post-smolts in RAS. This...
Citations
... One downside of immersion approaches is that there may be large volumes of water containing steroids that must be disposed of after treatment. Steroids may be cleared from water by means of ozonation, activated carbon, and/or chlorination (Good et al. 2017;Reis and Almeida 2019). With regard to the steroid-treated fish themselves, numerous studies have demonstrated that steroids are rapidly cleared after steroid treatment, with body burdens reduced to those found in sexually maturing fish within a matter of days (Fagerlund and Dye 1979). ...
The ability to survive and pass one’s genes to the next generation through reproduction is key to the perpetuation of life. Reproduction influences species survival and abundance in the wild and levels of production in agriculture. It is therefore unsurprising that the study of reproduction and development of methodologies to assess it has been an important research area in fisheries and aquaculture science. Since the first edition of this book, the era of molecular biology was born. Advancements in so-called ’omics technologies (e.g., genomics, transcriptomics, proteomics), mostly driven by human medicine and pharmacology, have changed the methods landscape and are now frequently applied to model and even nonmodel fish species. Every year, in fact, conducting large-scale molecular studies in nonmodel species becomes significantly more achievable and affordable. The development and availability of molecular biology methods has by no means led to wholesale replacement or antiquation of classical methods; quite the contrary, as many classical techniques such as histology remain the gold standards for fish reproductive assessments.
In this chapter we briefly cover some of the most widely used methods for the study of fish reproductive physiology, including classical and newer approaches. The main audiences using these techniques are fishery and aquaculture scientists, and though there is limited interaction between these disciplines, many methods are shared, and research in each discipline does indeed inform the other; hence, both are considered here. We have adopted the standardized terminology proposed by Brown-Peterson et al. (2011) for describing reproductive development in fishes. This classification is based on the premise that most female and male teleost fishes go through a similar cycle of preparation for spawning, including development and growth of gametes, spawning, cessation of spawning, and preparation for the subsequent reproductive season. Following this scheme, fish can be classified within the following reproductive phases based on both macroscopic and microscopic/histological features: immature phase, developing phase, spawning capable phase, regressing phase, or regenerating phase (for details, see Brown-Peterson et al. 2011). It is also important to note that the terms mature or maturation are used to refer to the initial, one-time attainment of sexual maturity (i.e., puberty or adulthood), and not to individuals that are developmentally and physiologically able to spawn. Thus, a fish that has attained sexual maturity will never exit the reproductive cycle and return to the immature phase. Given the diversity of fishes (>33,000 extant species
identified), it should also be noted that this scheme may need to be adapted to the reproductive specificities of each species (e.g., semelparity, hermaphroditism, live-bearing) and the scope of the study under consideration.
We hope that this overview will be useful to readers and provide links to the broader scientific literature for detailed and specific questions regarding methods for species of interest. In an effort to provide a case study or continuum on reproductive assessment and manipulation in a single species, throughout the chapter we make special reference to Sablefish Anoplopoma fimbria (a.k.a. Black Cod), a species for which a number of reproductive methods have been recently applied for purposes of aquaculture and fisheries management.
... Mota et al. (2014) estimated cortisol clearance efficacy to be <99% in commercial RAS during baseline conditions. Still, studies comparing steroid concentrations in the make-up water (new water into the system) with concentrations in the rearing water have shown that waterborne cortisol and other steroids accumulate in the rearing water of commercial and experimental RAS (Mota et al., 2014;Good et al., 2017). In the present study, cortisol clearance efficacy was 99.8% 1 day before smolt insertion. ...
... Since steroids induce behavioral and physiological changes in fish by acting as pheromones, concerns regarding the behavioral and physiological effects of waterborne steroids in RAS have been raised (Mota et al., 2014;Good and Davidson, 2016;Good et al., 2017). However, these effects seems mainly to be induced by the sex steroids, and whether waterborne cortisol affects fish, has been questioned (Mota et al., 2017b). ...
... However, it is important to keep in mind that cortisol release and clearance rate were estimated assuming a quasi-steady state of hormone release during a smolt insertion event, while the results show a highly dynamic response to this perturbation. Other factors, which can contribute to the dynamics of waterborne cortisol in RAS, include changes in clearance capacity of water treatment processes, amount of new water into the system, and hormone concentrations in this make-up water (Good et al., 2017). Altogether, this accentuates the need for further studies on the underlying mechanisms of the dynamics of water cortisol concentrations, to refine waterborne cortisol as a non-invasive fish-based welfare indicator in commercial RAS. ...
Sampling protocols and water quality sensors have been developed to assess fish health and welfare in recirculating aquaculture systems (RASs). Still, the use of fish-based non-invasive welfare indicators, reflecting the physiological state of the fish, is limited in this type of system. Cortisol, the major stress-coping hormone in fish, diffuses through the gills. Consequently, waterborne cortisol is a potential fish-based non-invasive welfare indicator in RAS. However, its use in commercial rearing systems is sparse. In this study, we evaluated water cortisol levels and feeding behavior as welfare indicators of newly inserted smolt in a commercial RAS for harvest size Atlantic salmon. The RAS consisted of two parallel fish rearing raceways, raceways 1 and 2, sharing the same water treatment with common outlets and inlets. The smolts were inserted in raceway 1 while salmon that have been in the system for 6 months or more were kept in raceway 2. The smolt insertion period was 3 days. Samples for water cortisol levels were withdrawn the day before, 1 and 3 days after the smolt insertion period. Smolt insertion resulted in elevated water cortisol concentrations in the entire system, with the highest values in raceway 1, one day after smolt insertion. Estimated cortisol production in newly inserted smolt decreased over time, was similar to what has been reported in salmon adapting to experimental tanks. Feeding behavior indicated that the appetite was not fully resumed in the newly inserted smolts, while the appetite of fish in raceway 2 was unaffected by smolt insertion. These results, obtained in a highly intensive commercial RAS, suggest that waterborne cortisol together with feeding behavior can be used as indicators for adaptive processes associated with stress resilience in farmed fish. Thus, they are promising non-invasive indicators for assessing the impact of potential stressors on fish welfare in this type of rearing system.
... All photocatalytic studies were conducted at bench scale, except one performed at full-scale RAS (Rodriguez-Gonzalez et al., 2019) and two performed in pilot plants involving solar compound parabolic collectors (Pereira et al., 2013) and packed-bed photocatalytic reactors (Pestana et al., 2014). Likewise, the other studied technologies were performed at the lab scale, except three studies on UV-and ozonation-based processes implemented in RAS (Good et al., 2017;Klausen and Grønborg, 2010;Fig. 2. Total number of studies dealing with the application of AOTs in aquaculture farms (102) and the distribution of studies regarding the type of contaminant studied (i.e., organic MPs, bacteria or conventional pollutantse.g. ...
... Consequently, the treatment efficiency is often overestimated when synthetic solutions are used. In general, studies that do not spike the effluents correspond to those that implement AOTs in aquaculture facilities (Good et al., 2017;Pettit et al., 2014;Rodriguez-Gonzalez et al., 2019;Zhang et al., 2020a). The selection of high concentrations in most studies is related to the unavailability of the highly sensitive analytical apparatus required to assess the treatment performance at ng-μg⋅L − 1 levels of MPs. ...
... Nevertheless, the reported results demonstrate the potential of these innovative technologies, and more studies are necessary at full-scale to assess their performance under real conditions, as well as a comprehensive cost analysis. In fact, two studies involving AOTs (O 3 , UV/O 3 and UV/H 2 O 2 ) at full-scale RAS (Good et al., 2017;Klausen and Grønborg, 2010), highlighted the capacity of these technologies to remove MPs, indicating that further research is needed for the possible integration of AOTs into the existing water treatment systems, creating a new treatment approach that can remove MPs. ...
Aquaculture is the fastest growing animal food-producing sector. Water is the central resource for aquaculture, and it is essential that its quality be preserved. Micropollutants (MPs) can reach aquaculture through anthropogenic addition or inlet water, and may cause harmful effects such as endocrine disruption and antibiotic resistance, adversely affecting the fish species being farmed. Furthermore, the discharge of aquaculture effluents into the environment may contribute to the deterioration of water courses. In this sense, the implementation of environmentally responsible measures in aquaculture farms is imperative for the protection of ecosystems and human health. The European Commission has recently launched a guiding document promoting ecological aquaculture practices; however, options for water treatment are still lacking. Conventional processes are not designed to deal with MPs; this review article consolidates relevant information on the application of advanced oxidation technologies (AOTs) and constructed wetlands (CWs) (singly applied or combined) as potential strategies in this regard. Although 161 studies on the application of AOTs or CWs in aquaculture have already been published, only 34 focused on MPs (28 on AOTs and 6 on CWs), whereas the others reported the removal of contaminants such as bacteria, organic matter, solids and inorganic ions. No study coupling both treatments has been reported to date for the removal of MPs from aquaculture waters. AOTs and CWs are prospective alternatives for the treatment of aquacultural aqueous matrices. However, the type of aquaculture activity and the specifications of these available technologies should be considered while selecting the most suitable treatment option.
... However, a tangential inlet flow and central bottom drain have been the most common flow boundaries in several studies [46,49,50] . The physiological studies of Davidson et al. [16] and Good et al. [22] deployed circular RAS tanks with tangential inlet and Cornell type dual-drain system. Indeed, the combination of a central bottom outlet and an elevated wall drain is often used in circular RAS tanks to achieve a controlled flow pattern. ...
The salmon farming industry has recently shifted to larger culture tanks with greater water flows to optimize the land-based production, but tanks approaching 1000 m³ in volume create challenging hydrodynamics. This paper presents a computational study of four combinations of inlet and outlet designs of a commercial land-based aquaculture tank. Windows-based OpenFOAM solvers are used to solve the conservation equations for tank hydrodynamics with an implicit unsteady second-order Eulerian (finite volume) technique on unstructured hybrid meshes. The model is validated by the velocity measurements at discrete locations in the tank using acoustic doppler velocimetry. To understand the dispersion of biosolids in the tank, 500 particles with a uniform size of 200 µm are tracked in the Lagrangian frame. While the tank's Reynolds number varies between 2E6 - 3.5E6 depending on the flow exchange rate, the local Reynolds number at the inlet pipe is about 2E5 which discovers the drag-crisis phenomenon. The effect of inlet and outlet placement on the velocity, vorticity and turbulence is addressed. The existing tank design could be improved using the bottom-drain and corner-inlet options, which strengthens rotational flow with better uniformity. Such design change is also proved to provide better particle removal and thus ensure the improved self-cleaning ability of the tank.
... Obtaining information on the fate of estradiol and its metabolites in RAS type systems represents an initial step towards understanding the risk of environmental release and the means of effluent treatment, following which mitigation strategies could be developed (Good et al., 2017). The aim of the current study was to determine the concentrations of 17β-estradiol (E2) and its metabolites (i.e. ...
Recirculating aquaculture system (RAS) is being applied in many aquaculture industries as it provides an opportunity to produce fish in a contained system with minimal use of water. In proposed RAS-based farming of the American eel, 17β-estradiol (E2) is being investigated as an in-feed drug to feminize and increase growth of farmed eels. This creates potential for release of E2 and its metabolites from the eel RAS and information is needed to monitor and manage eel farm effluents to reduce impact on the environment. In the current study, the concentrations of E2 and its metabolites (i.e., estrone (E1) and estriol (E3)) were monitored from different compartments in the RAS and analyzed by liquid chromatography tandem mass spectrometry (LC–MS/MS). E2 levels ranged from 8 to 25 ng/L in the water recirculating within the RAS and declined to 2–6 ng/L in the weeks post-treatment. E1 levels were within similar ranges as E2, whereas E3 levels were below 2 ng/L throughout the study. The results were used to develop a computational model to describe the fate of E2 and its metabolites in the RAS, and to delineate the influences of metabolism and hydrodynamics for the removal of E2 by RAS processes. The rapid removal of uneaten feed and feces downstream of inventory tanks was found to be the most significant mechanism for the removal of 2–6% of the E2 added in feed daily, producing a concentrated effluent stream suitable for strategic treatment strategies. Greater than 94% of E2 added to the system with feed was either metabolized by the eels and/or bacteria in the biofilters of the RAS or was sufficiently bound to solids fractions in the solid samples to resist organic extraction and detection. Additionally, reducing daily water exchange from 23 to 7% of the system water inventory resulted in an increase of only 1 ng/L in E1 concentrations within the RAS system while a negligible change in the concentration of E2 was observed.
... For example, pharmaceuticals, hormones and bromate fall under the first category, whereas metabolites from cyanobacteria (cyanotoxins and off-flavours), polyphenols, such as terpenes, humic and fulvic acids fall mainly under the second one. Interestingly, recent researches demonstrate that photocatalysis and/or ozonation are able to degrade these kinds of compounds [16][17][18][19][20][21][22][23][24][25][26][27][28]. ...
... OZ is applied in aquaculture [7,[16][17][18][19][20][21], maintenance of aquaria [33,34], and water potabilization plants [35,36], thanks to the sterilization and purification capabilities. ...
A long-term test at a laboratory scale with a closed system (a coral reef aquarium)has been carried out to study the potentialities of photocatalytic ozonation and photocatalysis for the removal of noxious organic compounds in recirculating systems (aquaria and recirculating aquaculture systems)working with a minimum make up of new water. Attention has been focused not only on the depuration capabilities but also on possible negative phenomena, some of which could become apparent only at long times. After having tuned the system by setting appropriate operating conditions and procedures, positive results were obtained. In particular, it was observed that the alternation of photocatalytic ozonation with photocatalysis with definite cycle allowed to severely limit the presence of the organic compounds, which otherwise could accumulate in the system, and at the same time to control the formation of bromate, the ozonation side-product of main concern. In addition, the values of other parameters, which are important for water quality, remained at satisfactory values. It was also verified that the prepared photocatalytic films maintained a good photocatalytic activity even after several months of utilization in seawater. These results demonstrate that photocatalytic ozonation is a good candidate for water purification in recirculating systems in view of sustainable aquaculture.
... Davidson et al. (2011) demonstrated that application of low-dose ozone (ORP˜250 mV) in the same replicate RAS reduced true color by more than 90%, albeit while culturing rainbow trout at greater feed loading rates (3.98 kg feed/m 3 daily makeup water). During another onsite study evaluating the effect of ozone on waterborne hormone levels, ozone reduced true color by 74% from 20 ± 1 to 3.7 ± 0.3 Pt Co units, respectively (Good et al., 2017b), when operating RAS with feed loading rates comparable to the present study. In comparison, true color was reduced by approximately 20 and 22%, respectively, during the 0.10 and 0.30 mg/L PAA trials. ...
Peracetic acid (PAA) is an effective disinfectant/sanitizer for certain industrial applications. PAA has been described as a powerful oxidant capable of producing water quality benefits comparable to those expected with ozone application; however, the water oxidizing capacity of PAA in aquaculture systems and its effects on fish production require further investigation, particularly within recirculation aquaculture systems (RAS). To this end, a trial was conducted using six replicated RAS; three operated with semi-continuous PAA dosing and three without PAA addition, while culturing rainbow trout Oncorhynchus mykiss. Three target PAA doses (0.05, 0.10, and 0.30 mg/L) were evaluated at approximately monthly intervals. A water recycle rate >99% was maintained and system hydraulic retention time averaged 2.7 days. Rainbow trout performance metrics including growth, survival, and feed conversion ratio were not affected by PAA dosing. Water quality was unaffected by PAA for most tested parameters. Oxidative reduction potential increased directly with PAA dose and was greater (P < 0.05) in RAS where PAA was added, indicating the potential for ORP to monitor PAA residuals. True color was lower (P < 0.05) in RAS with target PAA concentrations of 0.10 and 0.30 mg/L. Off-flavor (geosmin and 2-methylisoborneol) levels in culture water, biofilm, and trout fillets were not affected by PAA dosing under the conditions of this study. Overall, semi-continuous PAA dosing from 0.05-0.30 mg/L was compatible with rainbow trout performance and RAS operation, but did not create water quality improvements like those expected when applying low-dose ozone.
... Microbial biofilms can establish inside of pipes and on submerged surfaces of unit processes throughout water reuse systems; therefore, it is difficult to significantly influence these microbial populations. During other onsite trials, heterotrophic bacteria counts were not significantly reduced even when applying powerful oxidants such as ozone (Davidson et al. 2011;Good et al. 2017) or peracetic acid (authors' unpublished data). Davidson et al. (2011) described trends for bacterial reduction by ozone, but the variability of bacterial counts among replicate RAS limited detection of significant differences. ...
A study was conducted to analyze the effects of snails (Physa gyrina) on biofilm, bacterial abundance, off-flavor-producing bacteria , and off-flavor compounds in reuse aquaculture systems cul-turing rainbow trout (Oncorhynchus mykiss). Eight experimental-scale systems were used, including four with and without snails. Mean heterotrophic bacteria counts in water were lower (P < 0.05) in systems with snails. Submerged surfaces of sumps containing snails were nearly biofilm-free, while sumps without snails were coated with biofilm. Geosmin levels in trout fillets from snail-stocked systems were generally lower but not statistically different from the controls. Rainbow trout health and performance was not affected by snail presence.
There are various types of IAS in which aquaculture and hydroponics are the two major combining techniques, namely called aquaponic systems. The system continuously recirculates water from the fish tank containing the metabolic waste of fish. The water passes through a mechanical filter that captures solid waste, and then goes through a biofilter, oxidizing ammonia to nitrate. The media beds, where plants and vegetables grow, are the next destination of the water, so the plants can absorb the nutrients, and finally, the water returns, purified to the fish tank (Fig. 5.1).
Aquaculture activities surge tremendously worldwide and intensively shifted the landscape of food consuming across the globe. As the fish catch production from natural environment has reached its limit, the public has begun to rely on farmed aquatic products for continuity of protein sources. The aquaculture industry is currently dominated by Asia and has evolved into multiple configurations to increase fish production. Nonetheless, the constituent in aquaculture wastewater (mainly from fish feed) and other pharmaceutical substances have raised public concern as those constituents are potent to jeopardize surrounding environment when released into the ecosystem. In order to minimize the impact of aquaculture wastewater, rigorous researches have been proposed and conducted to effectively treat aquaculture effluent. A thorough treatment mechanisms have been covered, of which the recirculation aquaculture system (RAS) is the most extensively implemented, other technologies introduced include biological, physical and chemical treatments. This review covers an in-depth analysis of these technologies, including their pros and cons, treatment efficacies and process intensifications. Bioreactor, bio-floc, wetlands and phytoremediation are among the biological treatment methods revealed in the discussion, while the physiochemical section encompassed an overview of adsorption, advanced oxidation processes (AOPs) and membranes technologies. Future recommendations are proposed in terms of aquaculture regulations to ensure sustainable aquaculture development.
