Dynamic of Nutrients in a Recirculating Aquaponic System Using Red Tilapia (Oreochromis Sp.) and Lettuce (Lactuca Sativa Varlongifolia)

A series of experiments were conducted to evaluate the fish and vegetable production in a recirculating aquaponic system In the first experiment, the efficiency of three recirculating aquaculture systems (plant as a biofilter, a simple handmade- biofilter and combination of both plant and biofilter) in the production of fish and removal of N-compounds were evaluated. It was concluded that all the systems were efficient both in the removal of N-compounds as well as giving high red tilapia (Oreochromis sp.) and lettuce (lactuca sativa var longifolia) production. Within a period of fish culture (15 weeks), and a period of lettuce culture (5 weeks), the yield of red tilapia and lettuce ranged from 13.61 to 19.41 kg/m3 and from 0.851 to 2.87 kg/m2 in the hydroponic area, respectively. Based on the results of the first experiment, the system with the use of plant as a biofilter was selected as a model for investigation of the nutrient removal and reabsorption in an aquaponic system The main parts of the system consisted of a black fiberglass tank (110L x 84 W x 100 H cm) equipped with three hydroponics troughs (110L x 30 W x 5 cm Depth), and a submersible pump (Model Aqua, 1500) for recirculating the water through the culture system In the second, third and fourth experiments, the total ammonia excretion by red tilapia (the endogenous ammonia excretion related to catabolism of body protein and exogenous ammonia excretion related to metabolism of feed protein), as well as gaseous ammonia escape rate during different stages of its growth from the culture system were evaluated. It was found that the weight of fish significantly affected ammonia excretion. The rate of total N content of feed excreted by red tilapia ranged from 31.10 to 54.20% for 20-200g red tilapia On average, 39.54% of the nitrogen content of fish feed was excreted as ammonia-N by red tilapia. Water recycling influenced the escape of ammonia due to ventilation an in the culture system. However, the rate of ammonia escaping from the system, decreased inversely with an increase in the fish weight. The percentage of escaped ammonia ranged from 7-72% of total ammonia excreted by fed fish

Automatic region-of-interest extraction in low depth-of-field images

PhD ThesisAutomatic extraction of focused regions from images with low depth-of-field (DOF) is a problem without an efficient solution yet. The capability of extracting focused regions can help to bridge the semantic gap by integrating image regions which are meaningfully relevant and generally do not exhibit uniform visual characteristics. There exist two main difficulties for extracting focused regions from low DOF images using high-frequency based techniques: computational complexity and performance. A novel unsupervised segmentation approach based on ensemble clustering is proposed to extract the focused regions from low DOF images in two stages. The first stage is to cluster image blocks in a joint contrast-energy feature space into three constituent groups. To achieve this, we make use of a normal mixture-based model along with standard expectation-maximization (EM) algorithm at two consecutive levels of block size. To avoid the common problem of local optima experienced in many models, an ensemble EM clustering algorithm is proposed. As a result, relevant blocks, i.e., block-based region-of-interest (ROI), closely conforming to image objects are extracted. In stage two, two different approaches have been developed to extract pixel-based ROI. In the first approach, a binary saliency map is constructed from the relevant blocks at the pixel level, which is based on difference of Gaussian (DOG) and binarization methods. Then, a set of morphological operations is employed to create the pixel-based ROI from the map. Experimental results demonstrate that the proposed approach achieves an average segmentation performance of 91.3% and is computationally 3 times faster than the best existing approach. In the second approach, a minimal graph cut is constructed by using the max-flow method and also by using object/background seeds provided by the ensemble clustering algorithm. Experimental results demonstrate an average segmentation performance of 91.7% and approximately 50% reduction of the average computational time by the proposed colour based approach compared with existing unsupervised approaches

Effects of diet containing different levels of yeast, Saccharomyces cerevisiae and plant proteins on growth indices, carcass biochemical composition and total intestinal bacteria count in a recirculating aquaculture system for rearing rainbow trout, Oncorhynchus mykiss

In this study, several balanced protein diets using plant proteins and yeast, were employed with the aim of reducing the fish meal in the diet. The experimental treatments included: control (T0) as commercial diet, (Faradaneh Co., Iran); treatment 1 (T1) containing 25% fish meal (FM) and 58% plant protein (pp); treatment 2 (T2) containing 23% FM, 4% yeast, 47% pp; treatment 3 (T3:  20% FM, 9% yeast, 52% pp); treatment 4 (T4: 18.5% FM, 14.5% yeast, 46% pp); treatment 5 (T5: 17% FM, 21% yeast, 41% pp); treatment 6 (T6: 10% FM, 25% yeast, 45% pp) and treatment 7 (T7: 28.5% yeast, 45% pp). A total of 160 rainbow trout Oncorhynchus mykiss fingerlings with an average weight of 38 ± 2 were randomly introduced into the 16 experimental tanks and cultured for nine weeks. The results showed that the growth performance of fish such as final weight, specific growth rates and protein efficiency rates increased in T3 in comparison with the other treatments (p<0.05). The highest carcass protein was observed in T3 and the highest fat was observed in the control group. The highest total count intestinal bacteria was observed in treatment 5 and the lowest in control and treatment 2 (p<0.05). The best experimental diet was recorded in T3. It was found that growing rainbow trout using diets containing vegetable proteins, yeast, without fish meal is possible

Investigation of different levels of glycerol on cyst hatching percentage, total length and survival of Phallocryptus spinosa and Artemia franciscana

Artemia and fairy shrimps due to propitious size and wide distribution throughout the world, purvey ample feed resources with relatively favorable nutritional value to profitable aquatic species. Ambient water physical-chemical properties affect the biological function of zooplanctonic cysts. Glycerol is an alcoholic compound which is soluble in water and it  has three hydroxyl groups that are responsible for solubility in water. There is a relationship between the presence of free glycerol in water and cysts metabolic rate and dormancy duration. The present study aimed to investigate the effects of different levels of free glycerol in the hatchery water on hatching percentage, total length of nauplius and mortality rate of Phallocryptus spinosa and Artemia franciscana cysts. In this experiment, four triplicate treatments including 0% (control), 0.1%, 1% and 10% of glycerol were used on A. franciscana and P. spinosa hatchery water for 48 hours and 72 hours, respectively. The results revealed that 0.1% glycerol was the most efficient level for hatching percentage of P. spinosa cysts with 28.86±1.6%. Also, the size of total length of newly hatched nauplii in this treatment was 0.75±0.08 mm that was significantly greater than the other treatments (P≤0.05); there was no significant difference in the mortality percentage between this treatment and the control treatment. In A. franciscana, the highest hatching rate (68.33±4.71%) and nauplius length (0.90±0.08 mm) were recorded in the 1% glycerol treatment. According to the results, glycerol at 0.1% level for P. spinosa and 1% level for A. franciscana are suitable in the cysts hatching media to increase hatching rate and nauplii performance. Our work could contribute to a better understanding of the hatching biology of dormant life stages in zooplanctonic crustaceans

Hydrocortisone treatment may enhance survival and stocking of Beluga sturgeon (Huso huso Linnaeus, 1758) in estuaries of the Caspian Sea

Beluga sturgeon (Huso huso Linnaeus, 1758) fingerlings are released into the Caspian Sea for recruiting and enhancing commercial and recreational fishing purposes. These fingerlings are reared in fresh water, but released to the estuaries that may be caused mortalities due to acute osmotic stress. In this study, the fingerlings in whole (in vivo) or their gill tissue (in vitro) were exposed to three different levels of ‘the stress hormone’ cortisol (3, 5, 7 mg L-1 hydrocortisone sodium phosphate) for 24 hrs. The effects of treatments on blood cortisol levels and the size and numbers of gill chloride cells were monitored. In each case, hormonal treatment significantly increased blood cortisol levels and also the number but decreased the size of the chloride cells. We conclude that bathing in hydrocortisone could promote the survival rate of the fingerlings in brackish water and may be have a positive effect on their osmoregulation potentiality

Assessment of three Different Recirculating Tilapia Culture Systems Using Biological Filters and Mineral Nutrient

In this study, using different biological factors, we tried to remove the fish metabolites and improve the water quality in the culture system. Therefore, operation of some recirculating system were investigated during a 2-month culture period. The biological factors were bacterial (aerobic and none aerobic bacteria, in two separate departments), Lemnea plant and hetrotrophic bacteria for formation of biofloc with adjusting the ratio of C/N. The treatments included 1- a system consisted of the plant (P), 2- a system comprised the plant and biofilter (PB), a system containing of the plant, biofilter and biofloc (FBP) and finally, a system without biological compartment just physical section as control. Twenty tilapia fingerlings (10 ± 0.5 g) were introduced in each experimental unit. The results indicated that efficiency of FBP system based on food conversion ratio, specific growth rate and survival was significantly higher than other culture systems (p<0.05). The fish were died at the 23th day of initiation of the study in the control system. The rate of Lemnea plant in the treatment P was significantly higher than in other treatments (p<0.05). The concentrations of Ca, P, nitrate, ammonia, nitrite and pH were significantly different among treatments. So that, these minerals in treatment FBP were lower than those in the other treatments at the end of the study. The results indicated that using different biological methods (together) in a tilapia culture system could be more efficient in the removal of fish metabolites, in addition to the improvement of fish growth and plant in an integrated fish and plant culture system

Cold-Resistant Heterotrophic Ammonium and Nitrite-Removing Bacteria Improve Aquaculture Conditions of Rainbow Trout (Oncorhynchus mykiss)

The aim of this study was isolation and characterization of heterotrophic bacteria capable of ammonium and nitrite removal at 15 \ub0C (optimal temperature for growing rainbow trout Oncorhynchus mykiss). Environmental isolates were grown in liquid media containing ammonium or nitrite, and best strains in terms of growth and ammonium or nitrite removal were identified via 16S rRNA sequencing. Dyadobacter sp. (no. 68) and Janthinobacterium sp. (no. 100) were selected for optimal adaptation to growth at 15 \ub0C and best ammonium and nitrite removal (P &lt; 0.05), respectively. A heterotrophic ammonium and nitrite removal (HAN) microbial complex, containing selected strains, was prepared and applied in a trout culture system. After 10 days, the effect of microbial HAN complex was investigated in terms of ammonium and nitrite removal, as well as stress and immune indices present in the plasma of cultivated trout. Compared to a standard cultivation setup, addition of the HAN complex had a clear beneficial effect on keeping the un-ionized ammonia and nitrite level below prescribed standards (P &lt; 0.05). This resulted in reduction of stress and immune reactions of cultivated fish (P &lt; 0.05), leading to an augmentation of final weight and survival. Application of the selected microbial complex resulted in a significant improvement of the aquaculture ecosystem

Simultaneous detection of Aeromonas hydrophila, and Escherichia coli in Rainbow trout (Oncorhynchus mykiss) by Duplex PCR

Rapid and accurate identification of microorganisms have a significant impact on strategies and fish health management programs. Hence, in this study a duplex PCR assay based on the 16s rRNA gene for simultaneous detection of Aeromonas hydrophila RTICC 1032 and Escherichia coli RTICC 2325 from pure cultures, and challenged fish tissues was performed and their results were compared with the results of single PCR assays for each bacterium. For this purpose, an experiment with three treatments including artificially infected with A. hydrophila, E. coli and a mixture of them with a control group was designed. Fish were injected intraperitoneally with 1 ml of sterile physiological saline containing 106CFU/ml of the corresponding bacteria. Samples were collected from liver, kidney and spleen 48 hrs post-injection. A duplex PCR based 16S rRNA genes was developed for the simultaneous detection of A. hydrophila and E. coli. The PCR reaction conditions were optimized to permit detection of organisms from agar plates and fish tissues in less than 8 hrs. Each of the two pairs of oligonucleotide primers exclusively targeted 16S rRNA gene of the specific microorganism. When duplex PCR assay was used to simultaneous detection of the pathogens in asymptomatic fish, spleen and liver were negative for A. hydrophila, whereas kidney was positive for two bacteria. Samples that were duplex PCR negative were also negative by the culture method. On the whole, the duplex PCR has advantages in terms of its accuracy, sensitivity, ease of use, time of length analysis and cost-effectiveness compared to the single PCR and traditional method

Evaluating the water quality changes and formation of Bio-Floc in a zero-exchange water of common carp (Cyprinus carpio) culture system using different ratios of carbon to nitrogen (C:N)

The Bio-Floc has more efficacies compared to fixed Bio-film for removing the nitrogen compounds in water recirculating fish culture system. In this trial, a completely randomized experimental design was run to evaluate the roles of three different ratios of carbon to nitrogen (C:N) including 10 (treatment 10 = T10), 15 (T15) and 20 (T20), into the carp culture systems on growth and water quality. The mean individual weight was significantly higher in T20 compared to the other treatments. At the end of the experiment, the fish attained from 70 to 552.8, 704.7 and 708.8 g in T10, T15 and T20, respectively. The FCR, ammonia and nitrate concentrations were significantly higher in T10 compared to the other treatments (p<0.05). Concentration of ammonia in T10, T15 and T20 were 78, 29.9 and 29.9 mg/L, respectively.  A depletion trend was recorded in pH in all treatments during the experimental period. The electrical conductivity (EC) and Bio-Floc formation rate increased in all treatments and was significantly higher in T20. The EC of water were 1327.5, 1419.83 and 1419.83 mmos/cm in T10, T15 and T20, respectively. The rates of Bio-Floc reached to 71, 143, 163 mL/L in T10, T15 and T20, respectively. The results of this experiment indicated that using molasses to adjust C:N ratio of water at 20, enhances formation of Bio-Floc, carp growth rate and water quality in a zero-exchange water system

Effects of different photoperiods on the survival and growth of beluga sturgeon (huso huso) larvae

Effect of different photoperiodic regimes was evaluated on growth performance and survival rate of the Beluga (Huso huso) prelarvae and larvae. Newly hatched prelarvae were stored in 5 round fiberglass 500‑L tank with different photoperiod (24L:00D, 18L:06D, 12L:12D, 06L:18 D, 00L:24D) till 50 days post hatch with three replicates. Light intensity was 200 lux during the experiment. Feeding was started from 8 days post hatch using live artemia nauplii. Higher total length, survival rates and lower body area, yolk area for beluga prelarvae obtained in long light photoperiods (24L:00D, 18L:06D). Also, higher growth parameters of the beluga larvae observed in long light photoperiods while different photoperiods had no effect on survival rate. The present study indicated that growth performance and survival rates of larvae are significantly influenced by photoperiod. The photoperiod 18L:06D resulted in the best growth performance and survival rate during early development of the beluga