نشریه توسعه آبزی پروری
سال پانزدهم شماره 4 (زمستان 1400)

Algae by consuming CO2, light, and nutrients in wastewater not only could reduce the environmental pollutants, but also could increase the productivity of biomass and value-added byproducts such as biofuels in their cells. On the other hand, molecular techniques such as Real-Time quantitative PCR (qPCR) helps to better identify the pathways of response to environmental conditions in algal strains. In this study, at the first, the properties of prospective biodiesel were evaluated for three algal strains (Chaetomorpha antennina, Ulva intestinalis, and Bryopsis pennata) grown on different light intensity (8100, 12150, and 16200 lux) and different CO2 concentrations (380, 5190, and 10000 ppm). Finally, the expression profile of three genes involved in CO2 sequestration (CA, CIA5) and light harvesting (CAB) was investigated in superior strain. The results showed that the light intensity of 12150 lux and CO2 concentration of 5190 ppm led to the highest lipid content (30 to 37%) for all three algal strains. Also, all microalgae used in this study have a good ability to produce biofuels. Moreover, it was observed that increasing CO2 concentration has led to a decrease in the expression of the CA gene, but the highest expression of the CIA5 gene was observed in 5190 ppm CO2 concentration. The highest CAB gene expression was also observed in 12150 lux. In summary, the control of expression of the involved genes could significantly determine the final lipid productivity as well as the properties of prospective biodiesel.

The use of dietary nucleotides in mammals and aquatic organisms has shown various positive effects on growth, immune system, gastrointestinal tract, and intestinal flora, improvement of reproduction, fat metabolism and increased resistance to diseases. The aim of this study was to determine the effect of dietary nucleotide (vanagen) on growth, survival and carcass composition in sterlet fish (Acipenser ruthenus). For this purpose, fish with an average weight of 95±1 g were divided into 5 treatments with 3 replications. The fish were then fed a diet containing 0, 0.15, 0.25, 0.35 and 0.5% nucleotide supplements for ten weeks. The results showed mean of final weight, weight gained (WG), specific growth rate (SGR), and protein efficiency ratio (PER) increased significantly with increasing nucleotide levels (P<0.05), and in the treatment containing 0.5% of nucleotides were the highest. (FCR) was the lowest in the treatment containing 0.5% (P<0.05). According to the results, the amount of protein and carcass fat in 0.25% was the highest and the lowest was observed in the control treatment (P<0.05). The results showed addition of dietary nucleotides to the diet of sterlet fish improved growth indices such as body weight gain, specific growth rate, and protein efficiency rate, feed intake and reduced feed conversion ratio. According to the results, concentrations between 0.25-0.5percent of vanagen nucleotides are recommended to achieve optimal growth and carcass composition in sterlet.

Laboratory examinations on the effect of different densities on production of beluga and Nereis diversicolor worm and purification of total organic matter was carried out in an integrated system. Juvenile beluga with initial weight of 140.44±0.32 g were reared during 60 days with three densities of 2, 4 and 8 fish per tanks. Outlet water of the fish tanks was entered to the Nereis worm tank then was entered to the biofilter tank then after cleaning on this tanks water was returned again into the system. In this system, the Nereis worm was used both as a bioremediator and also byproduct. The results showed that growth factors of fish and increasing of density have related inversely. So that the maximum percentage of body weight increase and weight gain of beluga were 93.86±1.5% and 124.61±1.7 g respectively in low density. However, increased density caused increases in production of fish per unit area. So that highest final biomass of juvenile’s 5.28±0.09 kg/m2 were observed in high density. The lowest amount of total organic matter on the substrate with 2.66±0.94 g/mg was related to high density. The results of this experiment showed that the reliable stocking density is 8 per tank for fish production and bioremediation efficiency of system.

The polymerase chain reaction (PCR) was applied to create the colored transgenic ornamental zebrafish with the specific primers designed for muscle promoter of two genes and genes fragments cloned in Tol2 vector containing GFP gene in the ORF region. The 2000 bp and 2300 bp fragments of MYLZ2 and CKMB promoters' genes respectively were amplified by PCR, cloned into Tol2 plasmid expression vector containing SalI restriction enzyme site and transformed into E. coli Dh5α. Positive clones were tested for having fragments by colony PCR with anchor primers and subcultured for extracting recombinant plasmid miniprep. The extracted recombinant plasmid was tested with SalI enzyme digestion and sequenced with universal primers. Positive recombinant plasmids were applied for injection with transcript produced synthetically in the lab into zebrafish one-cell embryo. In this study, 2000 bp and 2300 bp fragments of MYLZ2 and CKMB promoters, respectively, were cloned in an expression vector Tol2 and confirmed by PCR, sequencing and enzymatic digestion. Also, recombinant plasmid was subcultured and purified for injection with a synthetic transcript. One-cell embryos injected by coinjection materials (recombinant plasmid and transcript) were tested by fluorescence microscope for positive GFP expression, where a few offspring of F0 generation were positive for GFP expression in their muscles. Recombinant plasmids with muscle-specific promoters (MYLZ2 and CKMB) were able to induce expression of GFP in some F0 embryos in a transient form and could be applied for consolidation in the next fish generation.

In this study the effects of replacing fish meal with yeast (Saccharomyces cerevisiae) on feeding and growth in rainbow trout (Onvorhynchus mykiss) fry were analyzed. The experiments of this study were conducted for a period of 10 weeks during summer 2019 in a fish farm located in Chahar-Mahal and Bakhtiari Province (Iran). In treatments used in this study, different ratios of fish meal and yeast were used in production of experimental fish food plates: 1) only fish meal, 2) 66% fish meal and 33% yeast, 3) 66% yeast and 33% fish meal, and 4) only yeast. Based on the results of this study the first two treatments in which only fish meal and 66% fish meal plus 33% yeast were included as animal protein sources were significantly better compared to the 3rd and 4th treatments regarding growth indices (mean final weight, specific growth rate, and condition factor). There were no significant differences observed among treatments for hepatosomatic and visceral indices (P>0.05). The best food conversion ratio (FCR), protein efficiency ratio, and food efficiency were observed in treatments 1 and 2, which differed significantly from other treatments (P<0.05). The total feed consumption by each individual and the total daily food consumption were not significantly different among treatment used in this study (P>0.05). In conclusion, it can be proposed that replacement of 25-50% fish meal with yeast in fish feed plates can provide a more economic fish food.

The aim of this study was Comparison of adjuvant (Montanide™ ISA 763 AVG) and licorice extract (Glycyrrhiza glabra) impacts on the growth performances and survival of rainbow trout vaccinated with lactococcosis vaccine. For this purpose, rainbow trout with an average initial weight of 72±3 g with four experimental treatments including control, vaccine, vaccine with Montanid safety vaccine and vaccine with licorice extract and each treatment containing 30 fish in 3 repetitions in 12 tanks 1,000liter was divided into a closed-circuit breeding system, and after adapting to the new conditions, the midwives first received the vaccine for 24 hours and after anesthesia with clove essential oil by intraperitoneal vaccine or vaccine containing immunosuppression and herbal extract. The fish were then fed for 8 weeks with extruded food faradaeneh and according to the factory's instructions. At the end of the period, growth indicators were analyzed by anesthesia and biometrics and the survival rate was determined. The highest final weight was (102.07±2.49 g and 100.47±3.27 g), respectively, for vaccine-containing montanide and vaccine-containing licorice extracts (P<0.05), respectively. Also, the highest percentage of survival in the vaccine group contained Montanid immunosuppression (96.66±3.33%) and the lowest rate in the control group (20±2%). The results of this study showed that the addition of Montanid's safety aid and licorice extract did not have a negative effect on salivary growth index, while improving some of these characteristics.

With the development of aquaculture in the marine fish sector, the identification of the nutrient composition required by larvae in the early stages of life has more considered. Despite the obvious importance of nutrition in the development of larvae of Sparidentex hasta, which is an economic species in aquaculture at; the south of the country, due to the small size and sensitivity to manipulation of marine fish larvae, little information is available about nutritional needs. Embryo and yolk sac compounds are affected by reproductive nutrition and according to the vital role of fatty acids in membrane permeability in the larval stage; it is possible to increase the survival rate of larvae by proper management of the fatty acid compounds required at the beginning of initial feeding (dry food or live food enrichment). In this study, samples were taken in three stages of gastrula, at the time of yolk sac uptake and three days after complete yolk sac uptake (beginning of active feeding). It was then stored in liquid nitrogen and -80 ° C freezer until laboratory work was performed using GC gas chromatography. The most abundant fatty acids were oleic and palmitic and there was a statistically significant difference in different stages of fatty acids (P<0.05). According to the results in SFA and PUFA up to larval stage, the trend was increasing, and in MUFA, oleic, it was a decreasing trend. The reduction of some fatty acids is because of energy consumption and further increase is for the role of storage, especially in membrane tissue. Therefore, the amount and ratio of fatty acids in the early stages of the life of the Sparidentex hasta determines the minimum larval requirement in the initial diet.

This research was conducted in order to find the abilities of the downstream river of Ardabil Yamchi Dam and to determine suitable aquaculture places and to estimate the amount of production. For this purpose, available meteorological and climatic information of the region and data obtained from monthly and seasonal sampling in the field of physical and chemical factors of water, discharge and flood status, phytoplankton, zooplankton, benthic and fish communities, pollutants including heavy metals and agricultural pesticides and groundwater status were examined. The results of physical and chemical factors of water showed that almost all factors are in the right range of salmon farming. Bacillariophyta branch was predominant phytoplankton. According to benthos, biological index in stations 1 and 2 was very good to excellent. Also, 6 fish species from families of Cyprinidae and Nemacheilidae were identified in river. The amount of heavy metals examined was within the allowable standard range. Geophysical studies of groundwater showed that the thickness of the water layer is about 20 to 30 meters and acceptable to drinking according to Schuler diagram. The data showed that in general the Yamchi River can be exploited for cold-water aquatics, especially rainbow trout, and it is not possible to culture warm-water fish. Also, various rearing systems including race way and preferably a semi-recirculation system were proposed. In the current conditions of the river, if the minimum potentials of the region are used for aquaculture, production of at least 65 tons by race way up to a maximum of 650 tons in the semi-recirculation system and in case of allocating special water directly from Yamchi Dam Lake for aquaculture, a minimum of 300 to a maximum of3000 tons of salmon was predicted, respectively. In addition, it was recommended that aquaculture complexes be established instead of individuals.

The emergence of newly released nanoparticles in water results in stress response of fishes, which ultimately affects the physiological state and reduces the immune function of fishes. Therefore, it seems the use of immune stimulants such as molasses is very necessary. In this study 250 common carp were exposed to molasses in four groups, with no molasses (treatment 1), diet containing 0.5% molasses (treatment 2), 1% molasses (treatment 3) and diet containing 2% molasses (Treatment 4) for 42 days. Each group were exposed to 50% of lethal concentration of nano-iron for 14 days. Then, various indices such as soluble protein, alkaline phosphatase, lysozyme and immunoglobulin were measured in mucus. Results showed that total experimental treatments had a significant effect on mucus immune parameters (P<0.05), so these indices were affected by treatments fed with molasses increased with the increase of molasses concentration, in the treatment of nano-iron and in the treatment of nano-iron and molasses, the amount of this indicator increased significantly. The overall conclusion of this study shows that molasses, iron nanoparticles, molasses and iron compound increased the mucosal immune parameters.

In order to investigate the efficiency of farms and the rainbow trout production function, the study was carried out at rainbow trout breeding farms in Alshtar city in Lorestan province during 2017. The data collection method was interviews and questionnaires. Data on production functions were estimated by Cobb Douglas functions and technical efficiency by deterministic parametric frontier (DPF) analysis method. The average technical, allocative and economic efficiency was 62.1%, 57.7% and 54.6%, respectively, that indicating significant potential of the units in increasing their efficiencies. The results of trout production function showed that the amount of feed intake and the area of fish farm with elasticity coefficients (0.369 and 0.270) had the most effect on trout production (P<0.01). The results showed that most trout breeding farms in Alshater due to lack of observance of economic principles in management, lack of knowledge of the factors affecting the production had low efficiency and profitability. In general, according to the results, there was a considerable gap between the units studied in Al-Shater city in terms of economic performance. This is due to the lack of attention to management issues in choosing the right combination of inputs (low allocative efficiency), respectively. Therefore, improving the conditions of breeding units, including nutrition and hygiene, is necessary to increase the efficiency and production of fish farms units in Alshtar.