Culture Tanks Research Articles

External Asymmetry and Pectoral Fin Loss in the Bamboo Sole (Heteromycteris japonica): Small-Sized Sole with Potential as a Pleuronectiformes Experimental Model.

Pleuronectiform fish develop marked external asymmetry in eye location and skin color at metamorphosis. The bamboo sole, Heteromycteris japonica, also exhibits loss of the pectoral fins at metamorphosis. Because of its small body size, short generation time, and long spawning season, we focused on the bamboo sole as an experimental model to investigate metamorphic asymmetry and pectoral fin loss during development. In the present study, we utilized a small-scale culture system to evaluate bamboo sole larvae and larval development, and a microinjection system for fertilized eggs. The culture system described here uses an 18 L culture tank for rotifers (the first diet for larvae) and 5 L plastic beakers for larval culture. Under this system, most larvae completed metamorphosis, including one-eye migration and pigmentation of the ocular side, by 23 days postfertilization (dpf) at 25°C. Larvae at density of 120-150 per liter were grown from hatching to 23 dpf with a survival ratio of 60-75% per beaker. Pectoral fins, including coracoid and disk cartilage, formed but were completely lost in late metamorphosis without formation of proximal radials and fin rays. The microinjection system designed here is adequate for the bamboo sole and allows injection of 100 one-cell-stage embryos per day. We expect that the culture and microinjection systems described here will facilitate the use of the bamboo sole as an experimental model organism in developmental biology.

Coral larvae for restoration and research: a large-scale method for rearing Acropora millepora larvae, inducing settlement, and establishing symbiosis.

Here we describe an efficient and effective technique for rearing sexually-derived coral propagules from spawning through larval settlement and symbiont uptake with minimal impact on natural coral populations. We sought to maximize larval survival while minimizing expense and daily husbandry maintenance by experimentally determining optimized conditions and protocols for gamete fertilization, larval cultivation, induction of larval settlement by crustose coralline algae, and inoculation of newly settled juveniles with their dinoflagellate symbiont Symbiodinium. Larval rearing densities at or below 0.2 larvae mL−1 were found to maximize larval survival and settlement success in culture tanks while minimizing maintenance effort. Induction of larval settlement via the addition of a ground mixture of diverse crustose coralline algae (CCA) is recommended, given the challenging nature of in situ CCA identification and our finding that non settlement-inducing CCA assemblages do not inhibit larval settlement if suitable assemblages are present. Although order of magnitude differences in infectivity were found between common Great Barrier Reef Symbiodinium clades C and D, no significant differences in Symbiodinium uptake were observed between laboratory-cultured and wild-harvested symbionts in each case. The technique presented here for Acropora millepora can be adapted for research and restoration efforts in a wide range of broadcast spawning coral species.

The effects of ozonation on select waterborne steroid hormones in recirculation aquaculture systems containing sexually mature Atlantic salmon Salmo salar

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 in 6 replicated RAS containing a mixture of sexually mature and immature Atlantic salmon Salmo salar to determine whether ozone, as typically applied in RAS to improve water quality, is associated with a reduction in waterborne hormones. Post-smolt Atlantic salmon (1253±15g) were stocked into each RAS; 109 of 264 fish placed in each system were sexually mature males, and 5 were mature females. Water ozonation, controlled using an ORP set-point of 290–300mV, was applied with the pure oxygen feed gas within the low-head oxygenators of 3 randomly selected RAS, while the remaining 3 RAS did not receive ozone. The RAS hydraulic retention time was 6.9±0.3 days. Study fish were raised under these conditions for 12 weeks; during weeks 10 and 12, triplicate water samples were collected from the following locations in each RAS: i) culture tank, ii) makeup water, iii) pre-biofilter, iv) post-biofilter, and v) post-gas conditioning. Concentrations of 3 waterborne hormones – testosterone, 11-ketotestosterone (11-KT), and estradiol (17β-estradiol) – were quantified using enzyme immunoassays (EIA). Estradiol was significantly reduced by ozonation; testosterone and 11-KT were also reduced by ozonation, although these reductions were not observed across all sampling locations and events. Testosterone and 11-KT concentrations, however, were significantly reduced following water passage through the biofilters of both ozonated and non-ozonated RAS. The results of this study demonstrate the potential for ozone to be used in RAS as a means of preventing the accumulation of steroid hormones. Further research is required to assess whether reducing hormones in this manner impacts precocious sexual maturation in RAS-produced Atlantic salmon.

Efficient and stable production of Modified Vaccinia Ankara virus in two-stage semi-continuous and in continuous stirred tank cultivation systems.

One important aim in cell culture-based viral vaccine and vector production is the implementation of continuous processes. Such a development has the potential to reduce costs of vaccine manufacturing as volumetric productivity is increased and the manufacturing footprint is reduced. In this work, continuous production of Modified Vaccinia Ankara (MVA) virus was investigated. First, a semi-continuous two-stage cultivation system consisting of two shaker flasks in series was established as a small-scale approach. Cultures of the avian AGE1.CR.pIX cell line were expanded in the first shaker, and MVA virus was propagated and harvested in the second shaker over a period of 8–15 days. A total of nine small-scale cultivations were performed to investigate the impact of process parameters on virus yields. Harvest volumes of 0.7–1 L with maximum TCID50 titers of up to 1.0×109 virions/mL were obtained. Genetic analysis of control experiments using a recombinant MVA virus containing green-fluorescent-protein suggested that the virus was stable over at least 16 d of cultivation. In addition, a decrease or fluctuation of infectious units that may indicate an excessive accumulation of defective interfering particles was not observed. The process was automated in a two-stage continuous system comprising two connected 1 L stirred tank bioreactors. Stable MVA virus titers, and a total production volume of 7.1 L with an average TCID50 titer of 9×107 virions/mL was achieved. Because titers were at the lower range of the shake flask cultivations potential for further process optimization at large scale will be discussed. Overall, MVA virus was efficiently produced in continuous and semi-continuous cultivations making two-stage stirred tank bioreactor systems a promising platform for industrial production of MVA-derived recombinant vaccines and viral vectors.

Survival and growth of geoduck clam larvae (Panopea generosa ) in flow-through culture tanks under laboratory conditions

The geoduck clam, Panopea generosa, is a species from the west coast of Baja California, Mexico, and the optimization of seed production systems is still a limiting factor for its aquaculture. In this study, a flow-through culture system was designed and tested in P. generosa larvae. Survival and growth was compared in triplicate 45-L fiberglass tanks using three larval densities (5, 10 and 15 larvae/ml). A head tank kept constant the water inflow, with a daily renewal rate of 1.8× tank volume. The food (Isochrysis spp.) was dosed according to the ingestion rate of larvae and the dilution rate. Survival decreased linearly during the first 10 days and reached asymptotic values of ca. 20% (15 larvae/ml) and 50% (densities of 5 and 10 larvae/ml) afterwards. Mean shell length at the end of the experiment (243 ± 1.8 to 270 ± 0.7 μm) was not statistically different among treatments, even though a trend towards higher gross growth rate was observed in the treatment with the lowest density (9.5 μm/day) relative to the rest of the treatments (8.5 μm/day). It is concluded that P. generosa larvae can be successfully grown in flow-through systems at maximum densities of 10 larvae/ml without significantly affecting their survival and growth rates. The system design was reliable, kept a constant water flow with reduced maintenance, and may represent an important option in the laboratory for increasing the stocking density of Panopea species during the larval phase.

Celulasas presentes en el tracto digestivo del camarón Litopenaeus vannamei

Las celulasas han sido clasificadas como endoglucanasas responsables de degradar celulosa, lo que le proporciona gran importancia en los procesos de la cadena alimentaria. Las celulasas y enzimas relacionadas son utilizadas ampliamente en varios procesos industriales. La celulosa es utilizada como una fuente nutricional por varios organismos, inicialmente se pensaba que únicamente microorganismos podrían degradarla, pero en la actualidad se ha encontrado celulasas en varios grupos de animales. En este trabajo, presentamos la detección de celulasas en extractos obtenidos del camarón Litopenaeus vannamei. En los ensayos se utilizaron individuos adultos y de los diferentes subestadios de L. vannamei colectados en los estanques de cría de las camaroneras de la Península de Santa Elena y Muisne, en las provincias de Santa Elena y Esmeraldas, respectivamente. Los hepatopáncreas, los estadios larvarios y los intestinos fueron homogeneizados en un homogeneizador Braun-Melsungen. Para la identificación de la celulasa, se utilizó como sustrato carboximetil celulosa (CMC) de mediana viscosidad. Para medir su actividad se añadió ácido 3,5 dinitrosalicílico (DNS). La actividad de la celulasa se determinó en base en la cantidad de los grupos reductores liberados. Para intentar determinar el origen sea endógeno o microbiano de las celulasas identificadas, se sometieron las muestras de adultos a antibióticos.
 
 En el subestadio zoea 3, se identificó una celulasa con un rango de pH óptimo entre pH 6.5 y pH 9.5. En las muestras de hepatopáncreas del camarón adulto se determinaron dos pH óptimos: uno en el rango ácido (pH 4-6) y otro en el rango básico (pH 10-11) lo cual sugiere la presencia de dos celulasas diferentes. En el intestino se observó actividad únicamente en el pH ácido (pH 4-6). La actividad celulolítica detectada en el desarrollo ontogénetico del camarón fue baja e inestable, una condición reportada también en el análisis comparativo de enzimas digestivas en otras cuatro especies de crustáceos. La actividad relativa de las dos enzimas del hepatopáncreas es similar y cada una de estas tienen una actividad cuatro veces mayor a la encontrada en el intestino. Estos resultados indican la presencia de dos celulasas presentes en el hepatopáncreas y se sugiere que una de ellas (con pH óptimo ácido) podría ser transportada desde el hepatopáncreas al intestino, aunque los datos no son concluyentes. En el caso de la celulasa con actividad a pH básico (10.5) puede tratarse de una celulasa producida de manera endógena por el camarón. Los datos reportados en este estudio sobre las capacidades de producción enzimática del camarón puede ser la base para futuros proyectos de investigación cuyo objetivo sea optimizar los procedimientos de cultivo del camarón.

Experimental study to evaluate the efficacy of locally available waste carbon sources on aquaculture water quality management using biofloc technology

Locally available carbonaceous waste products viz. wheat flour, rice flour and tapioca flour recovered from flour industries were explored as carbon source for biofloc production and water quality management in light limited indoor aquariums without any culture species. The main objective of the study was to find out the efficacy of locally available waste carbon sources on biofloc production. Tapioca flour was found to be encompassed with more than 90% carbohydrate and was observed more suitable for microbial growth, resulting in 41.4 and 33.7% higher floc formation as compared to rice flour and wheat flour, respectively. In addition, enhanced microbial protein assimilation of 33.5% was noted in tapioca flour biofloc system with respect to wheat flour (27%) and rice flour (23.75%). All biofloc systems showed adequate water quality management in terms of nitrite and total ammonium nitrogen removal from the culture tank. The study demonstrates the effective use of waste products from flour industries in biofloc technology to obtain multi-layer benefit as waste minimization and water treatment.

Mortality processes of hatchery-reared Pacific bluefin tuna Thunnus orientalis (Temminck et Schlegel) larvae in relation to their piscivory

In mass culture of Pacific bluefin tuna Thunnus orientalis, yolk-sac larvae of other species are fed as a major prey item to tuna larvae from 7 to 8 mm in total length. Marked growth variations in tuna larvae are frequently observed after feeding of yolk-sac larvae, and this variation in the growth of tuna larvae is subsequently a factor leading to the prevalence of cannibalistic attacks. To elucidate details of the mortality process of hatchery-reared tuna larvae after the initiation of yolk-sac larvae feeding, we compared the nutritional and growth histories of the surviving (live) tuna larvae to those of the dead fish, found dead on the bottom of the tank, as direct evidence of their mortality processes. Cause of mortality of tuna larvae 3 and 5 days after the initiation of feeding of yolk-sac larvae was assessed from nitrogen stable isotope and otolith microstructure analyses. Stable isotope analysis revealed that the live fish rapidly utilized prey fish larvae, but the dead fish had depended more on rotifers relative to the live fish 3 and 5 days after the initiation of feeding of yolk-sac larvae. The growth histories based on otolith increments were compared between the live and dead tuna larvae and indicated that the live fish showed significantly faster growth histories than dead fish. Our results suggest that fast-growing larvae at the onset of piscivory could survive in the mass culture tank of Pacific bluefin tuna and were characterized by growth-selective mortality.

Morphological and physiological differences among cultivation lines of Undaria pinnatifida in a common garden experiment using a tank culture system

Undaria pinnatifida is grown for food and industrial materials worldwide; therefore, advanced breeding is needed to meet quality and productivity requirements. In this study, we examined regional lines of U. pinnatifida from five cultivation sites in Japan with different environmental conditions: Oga (OGA, the northern Sea of Japan coast), Hirota Bay (HRT, the northeastern Pacific coast), Matsushima Bay (MAT, the northeastern Pacific coast), Naruto (the Seto Inland Sea coast) and Shimonoseki (SIM, the southern Sea of Japan coast). The sporophytes of these lines were cultured in a tank culture system under controlled environmental conditions, and their morphological characteristics, nutrient uptake kinetics (V max, K s and V max/K s ), and carbon, nitrogen and phosphorus contents were determined. Sporophytes from MAT grew faster, whereas those from SIM were smaller than those from the other sites. Although the blade thickness of sporophytes cultivated in the sea significantly differs among cultivation sites in the previous study, there was no significant difference in blade thickness among the regional lines cultivated in the tank. Sporophytes from OGA had the greatest V max/K s values and significantly greater nitrogen contents than the other lines. Therefore, the morphological characteristics of MAT and SIM sporophytes, and the nutrient uptake kinetics of OGA sporophytes may have a genetic origin. This indicates that these lines may represent useful resources for selective breeding, with MAT sporophytes providing faster growth and OGA sporophytes being well-adapted to low-nutrient conditions.

Design and performance of a recirculating aquaculture system for oyster larval culture

The major objective of this study was to introduce a newly designed recirculating aquaculture system (RAS) for oyster (Crassostrea angulata) larval culture. The system includes a culture tank, a suspended circular inlet-pipe, an upwelling aeration pipe, combined “banjo” sieves and a bioreactor chamber containing microalgae life keeping installation. The system was designed to resolve three problems: (i) stranding of larvae caused by water level changes and aeration, (ii) physical clogging of the screens and also (iii) deterioration of diet microalgae. The culture tank, “banjo” sieve size, water flow rate and light intensity for maintaining microalgae activity were all designed according to the pattern of larval movement and feeding behaviour. Results of this study showed the best average SGR for larval length was 6.36%/d (9.5 μm/d) and survival rate was 80%, with initial rearing density of 50 larvae/ml, indicating the problems above were fully resolved. Consequently, the system is fit for larval culture in mass production of oysters.

First Record of Captive Larval Culture and Metamorphosis of the Pacific Blue Tang, Paracanthurus hepatus

AbstractThe Pacific blue tang, Paracanthurus hepatus, is consistently among the top 20 marine ornamental species imported into the USA, with all specimens presently sourced from wild stocks. Captive culture of this species through metamorphosis has not been previously documented and fundamental information regarding reproduction, larval culture, and production techniques is scarce. This study aimed to elucidate methods that would advance our understanding and success with captive propagation of this species. A total of 50,000 eggs were collected from a single broodstock population and stocked in a 1000‐L tank. Beginning at 3 d posthatch (DPH), larvae were fed three times daily a diet comprised exclusively of copepod nauplii. At 12 DPH, enriched rotifers were first fed followed by powdered feed (20 DPH) and first instar Artemia (21 DPH). Large mortality events were observed at 7 and 20 DPH, corresponding with starvation and flexion, respectively. By 41 DPH, the majority of the remaining larvae began associating with the bottom of the culture tank. On Day 50, the first signs of blue pigmentation marked the beginning of metamorphosis. A total of 27 juvenile blue tangs were cultured during this trial. This effort represents the first successful culture of this species in captivity.

Growth parameters of whiteleg shrimp Litopenaeus vannamei and red seaweed Gracilaria corticata in integrated culturing method under zero water exchange system

Growth parameters of whiteleg shrimp Litopenaeus vannamei and red seaweed Gracilaria corticata were measured using integrated culturing method under zero-water exchange system in a 45-day period. A 2 × 3 factorial design was used with two levels of shrimp stocking densities and three levels of seaweed weight densities. G. corticata was cultured on a net tied to a round polyethylene frame. Culture tanks were filled with 750-L filtered seawater. A 40-W compact fluorescent lamp was hung over each tank to provide adequate and sufficient light for seaweed growth. Growth parameters of shrimp and seaweed such as specific growth rate (SGR), weight gained (WG) and average daily growth (ADG) were computed based on the initial and final weight of shrimp and seaweed. The maximum and minimum SGR of L. vannamei (1.97 and 1.69%/day) were observed in treatment S1A3 (25 shrimp/m2 and 400 g seaweed/m2) and S2A1 (50 shrimp/m2 without seaweed) respectively. The best survival rate (94.67 ± 1.33%), WG (129.9 ± 2.9%) and feed conversion ratio (1.67 ± 0.04) were also observed in treatment S1A3. The SGR of G.corticata in the treatment S1A3 (1.97 ± 0.00%/day) was significantly higher, compared to others. Strong positive correlations were obtained between the density of G. corticata and the growth parameters of L. vannamei. The red seaweed G. corticata could boost the growth parameters, survival rate and total production of L. vannamei under zero-water exchange system.

Effluent from a biofloc technology (BFT) tilapia culture on the aquaponics production of different lettuce varieties

Aquaponics production is emerging as an alternative for effluent treatment and aquaculture diversification. Also, aquaponics contributes to save water and for the maximum utilization of nutrients and culture areas. The objective of this research was to evaluate the effluent derived from biofloc technology (BFT) tilapia culture on the aquaponics production of three varieties of lettuce Lactuca sativa: red lettuce, butter lettuce, and crispy lettuce, using the clear-water recirculation system (CW) as a control. A total of six treatments were evaluated: BFT- RED; CW- RED; BFT- BUTTER; CW- BUTTER; BFT- CRISPY and CW-CRISPY, with three repetitions each during 21days. Two systems were used, BFT and CW, each one containing respectively: a 500L tilapia Oreochromis niloticus culture tank (∼70g initial weight), clarifiers, biological filter and nine floating beds hydroponic units. Planktonic community profile was weekly measured in BFT. The results suggested that BFT achieved better plant growth regardless of the variety. In addition, at the end of experimental period, a plant quality index was analyzed and indicated that BFT provided superior plants. The plant productivity (kgm−2) of the varieties red, butter and crispy on the BFT system was respectively 0.56, 1.94 and 1.36kgm−2, while on the CW was 0.28, 1.53 and 1.04kgm−2. In addition, the butter variety showed the best performance in each analyzed variable, followed by the crispy and the red. The most abundant groups of planktonics organisms (decreasing order) were the filamentous cyanobacteria, ciliated protozoa, chlorophytes, diatoms, oligochaetes and ostracods. The results indicate that BFT presented as a viable alternative for the aquaponics production, especially for the butter variety.

Alternative prophylaxis/disinfection in aquaculture - Adaptable stress induced by peracetic acid at low concentration and its application strategy in RAS

The application of peracetic acid (PAA) at low concentrations has been proven to be a broad-functioning and eco-friendly prophylaxis/disinfection method against various fish pathogens. However, there is lack of knowledge on how to apply PAA in a recirculating aquaculture system (RAS), and whether the application of PAA at low concentration can affect fish welfare. In the present study, PAA was applied in a pilot-scale carp (Cyprinus carpio) RAS (comprised of a fish culture tank of 1m3, a reservoir tank of 600L and a filter complex of 400L) every 3 or 4days for 5weeks, and the stress response of fish was monitored during every second PAA application by measuring cortisol in water. Results showed that the increase of water cortisol became less pronounced and the decrease of water cortisol occurred earlier after repeated applications of PAA, which indicates an adaptation of the stress response to PAA in the carp. Moreover, the mathematic model showed that the equal distribution of PAA in RAS was a slow progress, which depended on tanks size and flow rate. To avoid potential harm to the biofilter in RAS during PAA application, it's suggested that PAA should be applied only to the fish culture tank at a reduced flow rate. Statement of relevanceFish welfare becomes more and more important in aquaculture. However, there is a lack of knowledge if routine prophylaxis/disinfectant might affect fish welfare. In the present study, we tested how fish responded to repeated applications of peracetic acid (PAA) in a pilot-scale recirculating aquaculture system (RAS) via measurement of cortisol in water. The results showed that fishes reduced their stress during subsequent PAA application, indicating adaptation of fish to repeated prophylaxis/disinfection with PAA. Moreover, we established a model and measured the PAA concentration onsite to investigate the distribution of PAA in RAS. We found out that by simply adding PAA only to the fish culture tank with a reduced flow rate can avoid the potential harm on the biofilter. Findings from the current study provide insights that may prove of benefit to future treatment based studies.

Aquaculture of Sarcothalia atropurpurea tetraspores in New Zealand for carrageenan production

ABSTRACTThe endemic red seaweed Sarcothalia atropurpurea is a potentially valuable source of carrageenan, but no information is available on growing this species as a crop in New Zealand. Tetraspores released from wild-harvested reproductive thalli were settled onto strings and grown initially in tanks under two different day-lengths. Seeded strings were transplanted to open water at 2, 6 and 10 weeks after spore release. Gametophytic biomass was harvested twice by pruning plants approximately six and nine months after spore release. Sporeling length was correlated with day length during tank culture but these differences were not apparent after a period of open-water culture. Spores cultured with medium day-length for 6–10 weeks before transfer to open water grew into harvestable plants that contained similar amounts and types of carrageenan to that from wild material. These results demonstrate for the first time that aquaculture of gametophytic S. atropurpurea from tetraspores is possible.

Innovation in utilization of fish tanks for fish culture among fish farmers in Obio/Akpor Local Government, Rivers State, Nigeria

This study investigated innovation in utilization of fish tanks for fish culture among fish farmers in Obio/Akpor Local Government Area of Rivers State, Nigeria. Data for this study was obtained through the administration of questionnaire and scheduled interview to 120 sampled fish farmers randomly selected from the study area. Analysis of the data was done using descriptive statistics; frequencies, percentages and means. The results showed that fish farmers in the study area utilized innovation on fish tank; raise of platform to keep the tank (77.5%), construction of water inlet and outlet on tank (74.2%) and use of tank for incubation and hatching (64.2%). Fish farmers’ perception of the benefits on innovation utilization of fish tank include mobile and its position can be changed (80.0%), allows a quick view at the base (65.8%), easy to maintain (61.7%), cheap and economical (54.2%). Major constraint to innovation utilization on fish tanks is low stocking density (71.7%). It is recommended that fish farmers should explore all available sources of information on various innovations on fish tank for fish culture. Also, manufacturers of fish tanks should take into consideration various sizes that would accommodate high stocking density.Keyword: fish culture, fish farmer, fish tank, innovation, utilization

Commercial production of tiger puffer (Takifugu rubripes) in winter using a recirculating aquaculture system

Tiger puffer (Takifugu rubripes) is a promising species for aquaculture production because of its high value and limited supply. However, in the north of China, using sea cages to culture this species in winter is hampered by the fact that the seawater temperature is extremely low. Here, a large scale commercial production of tiger puffer has been successfully realized using a recirculating aquaculture system (RAS) from 3 October 2012 to 31 May 2013. The RAS was comprised of nine culture tanks (total water volume 200 m3) and stocked with approximately a total of 14400 fish (initial mean weight 160 g). The tiger puffer was hand-fed at a rate of 0.7% of total body weight per day, and the feed conversion rate was (1.21 ± 0.3) kg kg−1. The recycle water in RAS was treated by a sieve bend screen, a foam fractionator, a submerged biofilter, an UV sterilizer and a submersible aerator. During the whole culture period, an excellent water quality control was achieved in RAS. At the end of this experiment, the survival rate of tiger puffer was more than 98%. The final tank densities averaged 31.2 kg m−3, and the final individual mean weight was 440 g.

Assessment of Nutrients in Seaweed Tank from Land Based Integrated Multitrophic Aquaculture Module

Aquaculture industry is often generating waste that negatively impact to the environment. These wastes are rich in nutrients. Seaweed can utilize these waste nutrients. This experiment was conducted in a flow-through system (FTS) and a recirculation system (RS) in land-based integrated multi-trophic aquaculture module using seaweed Kappaphycus alvarezii as one of the components. The aim was to access the efficiency of the removal of nutrients in the integrated culture. Kappaphycus alvarezii was stocked at the density of 1 kg/tank in the rectangular plastic tank with 500 L of seawater. The waste generated from integrated multi-trophic aquaculture tanks was directed towards K. alvarezii culture tank. Water samples from inlet, outlet and inside of the culture tanks were drawn to determine the nutrients, namely, total nitrogen (mg/L) and total phosphorus (mg/L). Total nitrogen and total phosphorus in the seaweed sample and from the sediment of culture tanks were also analyzed. The total nitrogen amounting to 59.5% and 61.6% nitrogen was taken up by K. alvarezii in FTS and RS culture tank, respectively. The phosphorus showed the highest deposition of 61.1% and 31.6% in the sediment of in FTS and RS culture tanks respectively, whereas only 5.5% and 3.4% of phosphorus were taken up by K. alvarezii from FTS and RS culture tanks, respectively. The percentage of nitrogen remained in water was comparatively higher by 14.2% and 27.5% than phosphorus by 8.3% and 23.0% in water of both FTS and RS culture tanks, respectively. These results indicated that this species seaweed is efficient in the removal of nitrogen from both FTS and RS culture tank.

Design and Performance Evaluation of An Automated Filtration System for Sustainable Fish Culturing

The objective of this project was to design an automated filtration system for sustainable fish culturing and determine its efficiency of solids removal. The filtration system comprised of a sedimentation unit, two screen filters and its housing. Water flows from the culture tank to the sedimentation unit. Then, it passed through the screen filters before being stored in a reservoir. The system removed 85% of total suspended solids. Of the suspended solids removed, 63% was done by the sedimentation unit, 23% by the first screen filter and 13 % by the second screen filter. The results showed that sedimentation units play an important role in the aquaculture filtration system as they can reduce the operation cost of maintaining a filtration system.

Decolorization of Organic Compounds by Controlled Microalgal Culture

This study demonstrates that hydroxyl radicals (·OH) are generated by Chlorella vulgaris under culture conditions where only air is used for aeration, and that these free radicals can be used to degrade organic compounds. Methylene blue was used as a model organic compound and added to a Chlorella culture illuminated with visible light. As a result, methylene blue was essentially bleached entirely. Decolorization was likely due·OH because it was ameliorated by the addition of a radical scavenger (ethanol). Because this system does not require high-energy ultraviolet irradiation or hydrogen peroxide, it is more environmentally friendly than current wastewater treatment methods. Based on these results, we propose a system for decomposing organic matter in a micro algae culture tank, which has a lessened environmental impact than current methods.