فصلنامه بوم شناسی آبزیان
سال ششم شماره 4 (پیاپی 604، بهار 1396)

Aeromonas hydrophila is one of common bacterial disease in aquatic animals and its outbreak cause to decrease of aquatic production. Aeromonas disease is due to a protein toxin, aerolysin that exported by Aeromonas hydrophila. This protein toxin forms channels on target cells membrane, disrupting normal activities and cause to destruction and death of them. Aerolysin toxic protein is secreted by expression of the aerolysin gene. Aerolysin gene is 1482 bp and it’s an important and stable molecular marker for detecting possible of Aeromonas hydrophila infection. The PCR technique was used to study of this molecular marker. Different antibiotics used to control and treat of Aeromonas disease and tetracycline is one of the importances of them. Antibacterial mechanism of tetracycline is interference in the translation of aerolysin gene and therefore inhibition of protein synthesis in ribosome of bacteria, therefore they condemn dying. Knowledge of the antimicrobial mechanism of antibiotics can play an important role in finding suitable alternative materials for these synthetic drugs.

The aim of this study was to determine the optimal stocking density in koi carp (Cyprinus carpio var. Koi). For this reason, 2400 juvenile koi (1.28 ± 0.11 g) were stocked at five levels of density (50, 100, 150, 200 and 300 fish per m3) and reared for 11 weeks and growth performance, survival rate, and hematological parameters were evaluated. There was no significant difference between first three treatments, in weight gain, SGR, FCR, mortality and hematological parameters (P>0.05). The minimum weight gain and maximum mortality were observed in treatments 5 and 4, respectively. There was no significant difference between treatments in RBC, WBC, hemoglobin, hematocrit and total protein (P>0.05). The highest amount of immunoglobulin, cortisol, and glucose were observed in treatments 5 and 4, respectively (P<0.05). Levels of lymphocytes were decreased, and levels of neutrophils were increased, by increasing stocking density from 50 to 300 fish/m3. The minimum levels of lymphocytes (73.27±0.12%) were measured in treatment 5. Maximum levels of cortisol (173.97±1.47 ng/ml), was observed in treatment 5 on day 7. According to the results, stocking density more than 150 fish per m3, leading to the growth reduction and incidence of stressful conditions in koi carp, so the optimal stocking density, was 150 fish per m3.

In the current study, the effect of spoilage date palm (Phoenix dactylifera L.) fruit juice and molasses on Pacific white shrimp (Litopenaeus vannamei) cultured in a biofloc technology (BFT) surveyed. Four bioflocs were managed: BFT fed diets of 25% CP and palm juice (P25), diets of 25% CP and Molasses (M25), diets of 15% CP and palm juice (P15), diets of 15% CP and Molasses (M15) and clear water  without biofloc fed with 38% CP (Control) that were performed in triplicate. A 35-day study was conducted with 35 juvenile (average 5.37±0.33 g) shrimp randomly stocked in fifteen 300 L tanks at a stocking density of 175 shrimp m−3. The highest zootechnical performance (weight gain, significantly better feed conversion ratio (FCR), growth rate, survival and biomass increases) of the shrimps was rated in P25 and the lowest in the control (P <0.05). Moreover, the highest body weight index, efficiency feed, and specific growth rate shrimp both in P25 and the lowest in the M15 (P<0.05). P15 treatment with 72% profit was in the first step. Present results demonstrated that palm date juice biofloc appear to be more suitable and with a 15% - 25% CP feed could provide economy in fish meal and reduce production costs.

Nowadays, the entrance of pollutants including heavy metals in environment threatens the life of aquatic animals. In this study, the effect of zinc chloride (6 mg/l) and cadmium chloride (5 mg/l) exposure were studied on the activity of some metabolic enzymes in the liver, gills, brain and muscle in Snow trout (Schizothorax zarudnyi). The results showed that zinc caused a significant increase in AChE activity in the brain, AST activity in the liver and muscle and ALP activities only in the liver (p˂0.05). Exposure to cadmium significantly decreased acetylcholinesterase in the brain (p˂0.05). However, ALT activity in the liver and gills and AST activity only in the gills was increased significantly following cadmium exposure. Cadmium stimulatory effects on ALP in tissues were not statistically significant. Based on the above result, in this Species exposed to cadmium showed more toxicity than zinc, and the most sensitivity and susceptibility to the presence of cadmium and zinc in the environment was seen in livers of fish. Assessing levels of metabolic enzymes in the liver tissue and AChE enzyme in the brain tissue of Snow trout has the potential to be used as a suitable indicator to show heavy metal pollution in the aquatic ecosystem.

In addition to heavy metals, environmental factors affect to induce the synthesis of metallothionein (MT) contamination biomarker in vertebrates and invertebrates. Environmental parameters that were selected of nine stations in Chabahar Bay subtidal area (2013-14)  include temperature, salinity, dissolved oxygen and turbidity and heavy metals (copper, zinc, cadmium) in monsoon and post-monsoon, pre-monsoon, that studied relation them with polychaete metallothionein concentration. Total mean of MT was recorded in pre-monsoon 28.3±5.2, monsoon 15.50±4.9, and post-monsoon 21.39±4.37 µg/ g and ANOVA test showed significant differences among stations and seasons (p≤0.05). There were no significant correlation between metal concentrations in sediments and tissue in stations and seasons, also between metals and MT. Except for temperature and salinity were increased in monsoon, MT and other parameters showed a significant decrease in this season. In PCA test, three components of variance revealed a total of 75.24 variance percent that the second component with 28.73 variance percent was included oxygen and transparency and MT. Despite significant changes of MT and environmental factors in different seasons and also had not been recorded correlation of MT induction with metals, as the main factors in the induction, emphasis the role of Chabahar Bay environmental parameters on biomarker fluctuations. Among the factors under the PCA, dissolved oxygen of the main factors is effective in reducing the synthesis of MT in G.bonhourei.

Planktons are floating microscopic organisms that are confirmed as the primary producers and initial transporters of carbon to the higher levels of food webs. Moreover, planktons have an special importance and status in the habitat of aquatic ecosystems and therefore, their population dynamic assessment is essential in the study of these ecosystems. An extensive range of physical factors viz. nutrients, light, temperature and osmotic stresses influence the growth rate and population of phytoplankton. In the present study, the seasonal dispersion of planktonic populations was modeled in the Strait of Hormuz in 1998, using coupled one- dimensional model (GOTM/NPZD). The results of water column modeling in the summer exhibited the presence of very powerful thermocline and halocline layering in the water column, which maintain till the end of autumn and resulted in hindrance of the water column mix. The model output is indicative of the phytoplankton bloom in the spring followed by zooplankton bloom with a short delay. The zooplankton population bloom peak was at the end of spring. In winter, due to water mixing, temperature and salinity were homogenous in the water column and there were no observed changes in plankton population in studying area According to model output.

On the current study the effects of reducing branched-chain amino acids (BCAA) in diets of Sobaity sea bream in a constant level (40%) on growth and nutritional indices, pancreatic enzymes activity, whole body chemical proximate and amino acids, was assessed. This experiment was conducted in Marine Fish Research Station of Imam Khomeini harbor during July and August of 2014. For these purposes, four different treatments in triplicate were used during 42 days in the base of feeding with semi purified diets containing crystalline amino acids. The control diet was without any deficiency, the leucine (LEU), isoleucine (ILE) and valine (VAL) diets were deficient in leucine, isoleucine, and valine respectively. According to the results, the survival rate was not affected by treatments. Growth and nutritional factors including final weight, the percentage of weight increase, specific growth rate, protein efficiency and nitrogen retention were decreased in deficient diets related to the control but feed conversion ratio increased. Crude lipid decreased in all deficient treatments that showed disorder in lipid metabolism in regards to BCAA deficiency. Leucine, isoleucine and valine content of the whole body showed no significant differences between treatments in spite of deficiency in diets that showed amino acids sparing for these three essential amino acids. Reduction in pancreatic enzyme activity showed the relations of BCAA on secretion and activities of these enzymes.

This study focused on the accumulation of heavy metals (Couper, Nickle, Cobalt, chromium) in the edible tissues of Crucian. Sampling was done in 3 stations (West, Center, and East) of Anzali wetland in 2012. In this study, 10 samples were collected from each site in the standard weight by gill net fishing method and measuring the concentration of heavy metals was performed using flame atomic absorption spectrometry. results showed that the Levels of the heavy metals from maximal to minimal were Cu>Ni>Co> Cr, However concentrations of Cu, Ni, Co and Cr in edible muscle tissue crucian carp did not show the significant difference between stations (P>0.05). The accumulate heavy metals were compared with the standard of American FDA and the WHO. In this study, the toxicity of copper, cobalt, nickel, and chromium has been lower than permissible standards of WHO and FDA. According to the results, nickel showed amount near the permissible limit in Central and East Lagoon samples compared to standard WHO that must more do control over the productive resources of the metal around the basin's wetland. But crucian carp Anzali wetland hygienic in terms of being suitable for human consumption and its consumption lack the side effects for humans.

Gargoor, a wired traditional pot, is used to catch demersal fish on rocky substrates. The objective of this study was to investigate the effect of bait's type and shape on catching efficiency of Gargoors in Bandar Lengeh waters (Hormozgan). The study area was divided into near-shore waters (station 1) and off-shore waters (station 2). Sampling was performed by Seventy-two pots with the same soaking time (24 hours) during 48 cruises. Baits (Sardin, Cuttlefish, and Catfish) were cut into small pieces with similar weight (100 gr). Each bait was held in the cover (polyethylene net with 1 cm mesh size) and hanged inside the pots in two shapes (sliced and minced). Generally, the only bait type that had the significant difference between two shapes, was cuttlefish (p<0.05). Minced cuttlefish in the off-shore station in spring and sliced catfish in the near-shore station in summer had the highest and the lowest CPUE respectively. Based on our results, among the bait type, cuttlefish and between the bait shape, the minced shape had the best efficiency regarding the amount of catch. Therefore, to increase the amount of catch, using of minced cuttlefish is recommended.

This study was conducted to determine the original indicator of microbial pollution (Escherichia coli) in the major swimming areas of Bandar Abbas. Three major swimming areas were selected in Bandar Abbas that included Soroo, Khaje Ata and Ghadir Park.  During the present study, 30 sea water samples were gathered to evaluate the important indicator of microbial contamination and parameters such as pH, salinity was studied in autumn and winter 2015. Results showed that the mean of microbial pollution in swimming areas of Soroo, Khaje Ata and Ghadir Park in autumn was 770, 678.1 and 468.7 MPN/100 ml respectively, and in winter 537.2, 500.6 and 374 MPN/100 ml respectively that all results of microbial pollution were higher than national and global standards. The changes of microbial pollution and physical- chemical parameters were not significant in the two seasons. But the microbial pollution values of Escherichia coli in third stations were significantly decreased in comparison to seaside stations.

In the recent years, water pollution by contaminations are increasing rapidly, the problems of aquatic pollution with heavy metals which is one of the important pollutions indicate that necessary to assess in fish as an important source of human food. The aim of this study was investigated the sub-lethal effects of zinc chloride on hepatic enzymes activity in grey mullet (Mugil Cephalus). In this study after determining the LC50, Two sub-lethal treatments of zinc chloride includes (1.73 and 3.46 mg/L) was considered that any treatment has three replications. Fish were exposed to different doses of sub-lethal for 1, 7, 14 and 21 days and the end of each period samples of liver tissue was taken. The results showed that with increasing concentration of sub-lethal levels of aspartate aminotransferase (AST), alkaline phosphatase (ALP) and alanine aminotransferase (ALT) significantly increased (P≤0.05). Also with the prolonged exposure amount of enzymes AST, AST and ALT were increased significantly (P≤0.05). Results of this research showed those hepatic enzymes as stress indicator can be important factors to the investigation of eco-toxicological changes.

Given the importance of Artemia as the most live feed used in the aquaculture industry, the interaction between light intensity and pH was investigated in two levels of light 1000 and 2000 lux, and three levels of pH 8, 9 and 10 on the percentage of hatching, percentage of umbrella stage and percentage of unhatched cyst on Artemia franciscana. To determine the percentage of hatching, percentage of umbrella stage and percentage of the unhatched cyst, samples were taken from each replicate after 48 hours of the beginning of the incubation. According to the results, there was no interaction between the two factors of light intensity and pH (P = 0.383). There was no significant difference between two light intensities (p = 0.305). However, the highest hatching rate was observed at 2000 lux light intensity. The difference was significant between three pH treatments in the percentage of hatching and percentage of the unhatched cyst (P < 0.001). So that, the highest and lowest hatching rates were observed at pH 9 (73.03 ± 6.98 %) and pH 10 (47.67 ± 2.58 %), respectively. In order, the highest and lowest of umbrella stage were observed at pH 8 (5.96 ± 0.87 %) and pH 9 (2.31 ± 0.58 %). Also, the highest and lowest of unhatched cyst were observed at pH 8 (33.05 ± 3.67 %) and pH 9 (24.65 ± 3.56 %), respectively. According to the results of the present study, it can be suggested that for achieve the maximum hatching rate of Artemia franciscana cyst, it could be used water with a pH 9 and the light intensity 2000 lux

One hundred prisoner cichlid fish, (2.5 g), were fed with levels 1, 2 and 3 grams of prebiotic inulin per kg of diet over a period of 60 days. The highest weight gained in treatment 3 g of inulin, which was not significantly different from treatment  2 g of prebiotic dietary (P>0.05). The highest specific growth rate was measured in 2 and 3 g inulin. The highest feed conversion ratio and the highest protein efficiency ratio were belonged to control and 3 g inulin respectively. The maximum and minimum numbers of white blood cells and red blood cells were observed in 3 and 1 g of inulin, respectively. The highest amounts of hemoglobin and hematocrit belonged to the treatment 3 g of inulin. As a result, inulin can be effective in improving growth performance and hematological parameters in the amounts of 2 and 3 g per kilogram of diet in prisoner cichlid.

According to the different researchers and subjects were done about seaweeds, but, suitable species have not introduced to aquaculture. So, in this researching were comparison two important agarophytes Gracilaria and Gracilariopsis and was selected species that has suitable aquaculture factors. These aquaculture factors as following, quantity and quality of agar, required natural sources and easy access to stock assessment in the environment, possible of culture and adaptation, growing in more large sizes and speedy or increasing of production in per unit. sampling carried out Gracilaria and Gracilariopsis from intertidal Coasts of Sistan and Baluchestan and Hormozgan Provinces respectively from 2012 to 2014. The samples were transferred to the offshore Fisheries Research center of Chabahar and prepared for Extraction of agar. The results were showed that the average in one Kg of wet weight applied about 125 gr. Dry weight and from 100 gr. Dry weight applied 19.83 and 13.03 gr. gel powder from Gracilaria and Gracilariopsis respectively. At least, Gracilariopsis were selected for aquaculture.

This study aimed at investigating the antibacterial effects of extracts from leaf, fruit, and stem of Solanum nigrum on fish pathogenic bacteria. The extraction process was done using the rotary device. The leaf methanol extract and the fruit acetone extract (MIC and MBC of 25 and 12.5 ppm, respectively) showed stronger antibacterial properties. The Streptococcus iniae were the most resistant bacteria against case studies. The Aeromonas hydrophila has been found to be the most resistant bacteria in the fruit methanol and hexane extract. The stem and leaf acetone extracts showed the maximum diameter of the zones of bacterial growth inhibition on Yersinia ruckeri and Aeromonas hydrophila (concentration = 50 ppm) bacteria respectively. Furthermore, the minimum diameter of the zones of bacterial growth inhibition belonged to the leaf hexane extract on Yersinia ruckeri bacteria (concentration = 25 ppm). That using the leaf methanol extract and fruit acetone extract of Solanum nigrum is effective in treating bacterial diseases of the aquaculture.