فصلنامه شیلات
سال هفتاد و یکم شماره 1 (بهار 1397)

Myrcene is a compound found in many plants with beneficial health effects. Anesthetic efficacy of myrcene has been demonstrated in fish; however, there is no information about its effects on hematological effects. The aim of the present study was to investigate the effects of anesthesia with myrcene on hematological parameters of rainbow trout in comparison to eugenol. In this study, 240 rainbow trout (300 g) were used. The fish were anesthetized within 60, 180, 300 and 600 s with either myrcene or eugenol. To reach these time on anesthesia, 81, 30, 19 and 10 mg/L eugenol, or 531, 251, 177 and 111 mg/L myrcene were used. Blood samples were taken from the fish after anesthesia. Hematological parameters including blood cells’ number, leukocyte differential count, hemoglobin, hematocrit, MCV, MCH and MCHC were determined and compared among the treatments. Increase in anesthesia time of either eugenol or myrcene led to significant increase in hemoglobin and RBC, and the lowest value was related to 60 s. Among the myrcene treatments, increase in induction time results in a significant decrease in WBC and there was a significant difference between 60 and 600 s. Nevertheless, there was no significant difference in leukocyte differential count, MCV, MCH and MCHC among the treatments. Overall, it is concluded that increase in the time of anesthesia with eugenol and myrcene leads to increase in RBC and hemoglobin, which might be an indication of stress. In addition, it seems that anesthesia with myrcene and eugenol within 60-600 s has no certain side effects on the fish.

In this study, the effects of different levels of copper oxide nanoparticles (CuO NPS) were evaluated on hematological indices and liver enzymes activity of the grass carp (Ctenopharyngodon idella). Firstly, 150 fish (with mean weigh 38± 5 g) exposed under different concentrations of copper oxide nanoparticles for 96 hours and were recorded daily losses. As a result, the concentration of lethal toxicity (LC50) nano-copper oxide for grass carp was obtained 2589.14±0.5 mg/l. Then the fish exposed under sub-lethal concentrations (1/20, 1/30 and 1/50 concentration LC50) copper oxide nanoparticles for 10 days that were measured hematological indices and liver enzyme activities in fish. The results showed that the nano-particles causes changes in the blood parameters of the fish that these changes was affected by the nano-particles in blood indices by reducing the level of red blood cells (RBC), Hematocrit and increase in white blood cells (WBC) and liver enzymes in treatment groups (p<0.05). Finally, the results suggested that copper nanoparticles in the high level could side effect on the fish health. Therefore, preventing the entry of these new materials into the food chain of aquatic organisms seems to be necessary.

Oil pollutants are most important challenges in the development of marine aquaculture in Persian Gulf and Oman Sea. The aim of this study is investigate the effects of crude oil on some blood biochemical parameters in Asian seabass (Lates calcarifer) fingerlings. In the first stage of experiment, the fishes exposed to five experimental treatment for 14 days, including control, dispersed chemical as a positive control, water-soluble fraction of oil, mechanically and chemically dispersed crude oil with three repetitions. In the second phase of the experiment, to assess the ability of fish for physiological recovery, fish were transferred to a clean water for 14 days. Blood biochemical changes alanine aminotransferase (ALT) and aspartate aminotransferase (AST), glucose, triglycerides and total protein in blood plasma were measured. The results showed there wasn’t any significant difference in ALT activity and levels of total protein in all sampling time, AST activities in the blood plasma has significant increase in all crude oil treatments, after 7 and 14 days. This increased in mechanically dispersed oil treatment also continued to recovery phase. Blood glucose levels were decreased after one week exposed to crude oil treatments. After 14 days, the concentration of glucose in mechanically chemically dispersed crude oil treatments showed a significant reduction compared to control group. Levels of triglyceride in the all exposed treatments show significant decrease than controls groups. In conclusion, the results of this study showed that crude oil was able to alter some of the biochemical factors in fingerlings of Asian sea bass, and these effects are observed until 14 days after the end of exposed fish to crude oil.

Despite a good phytochemical potential, common water hyacinth (Echhornia crasipes) is considered among the worst weeds in the world due to its high reproductive capacity. Since medicinal use of the weeds is new and innovative approach for researchers, the present study was carried out to evaluate the antimicrobial effects of aquatic and hydro-methanolic extracts of common water hyacinth on pathogenic agents. The dried powder of common water hyacinth leaves was extracted with 80% methanol and water using soaking extraction. Antimicrobial activity was investigated on two aquatic and three clinical pathogenic species. The zone of inhibition was evaluated employing the agar diffusion test (well) using 5, 20, 100, and 400 mg/mL of each extract. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined using the agar dilution method. The hydro-alcoholic extract had the largest zone of inhibition on the aquatic pathogenic species Streptococcus iniae. The aqueous extract had the highest antimicrobial effect on Escherichia coli (P≤0.05).Paired comparison of the independent t-test on the effect of solvent type on the studied bacterial species showed that antimicrobial activity significantly increased against E. coli in hydro-methanolic extract and against S. iniae in the aqueous extract (P>0.05).MIC ​​ and MBC were 64-256 mg/mL and 128-512 mg/mL, respectively. The extract of the weed common water hyacinth has antimicrobial effects due to the presence of the effective secondary metabolites belonging to phenolic, tannin and alkaloid groups of compounds, and the type of solvent used is effective on the degree of antimicrobial activity.

The present study was conducted to investigate the bioaccumulation of copper in gill, mantle and foot of freshwater mussel, Anodonta cygnea. For this purpose, the bivalves were exposed to 125 μg/l of Cu during a period of 9 days and the Cu content were analyzed in the organs in days 3, 6 and 9. The results showed the concentration of Cu in unexposed mussels were the highest (10.35±2.12 μg Cu/g DW) and lowest (5.39±1.8 μg Cu/g DW) in the gill and foot, respectively. Cu concentrations were increased significantly (P<0.05) in all studied organs during exposure period compared to unexposed mussels. Among organs, the gill and mantle has the highest and lowest accumulation levels, respectively. Also, the highest and the lowest values of bioconcentration factor (BCF) were observed in gill and mantle, respectively. Based on the results, it can be said that Cu content in organs of A. cygnea (especially in the gills) is a proper indices of Cu pollution in the habitats of this organism.

Water quality management in brood-stock tanks, especially in terms of water salinity and water hardness, is of great importance to the reproductive performance of the crustaceans. The sodium absorption ratio (SAR) is a compound formula that has a ratio of sodium ion to total calcium and magnesium ions of water. The purpose of this study was to investigate the effects of different ratios of sodium to total calcium and magnesium of (SAR) in water on reproductive indices of female freshwater prawn. For this study, 12 tanks of 80 liters were assigned to 4 treatments with 0, 5, 10 and 15 sodium absorption ratios, each with 3 replicates. After the 60-day period of experiment, different reproductive indices were measured. The results indicated that the egg clutch somatic index (ESI) and the dry weight of eggs were significantly higher in treatment of sodium absorption ratio 5 than other treatments. Fertilized eggs percentage and hatched eggs percentage in control and 5 treatments were not significantly different but decreased with increasing of sodium absorption ratio in 10 and 15 treatments respectively. While different levels of sodium absorption ratio in water had no significant effect on total and relative fecundity parameters. Larval status index was significantly higher in treatment of sodium absorption ratio 5 than other treatments. Finally, the SAR at female brood-stock tank water can be optimized to achieve the highest reproductive performance and produce the best quality larvae. Therefore, it is recommended that the authorities of the reproductive centers that do not have natural brackish-water should adjust the water absorption ratio to 5 when making brackish-water for hatchery centers.

Lactococcus garvieae is one of the main causative agents of streptococcusis/lactococcosis in farmed fish particularly in rainbow trout causing remarkable losses each year. Genotyping of 20 isolates of Lactococcus garvieae strains recovered from the mortality of farmed rainbow trout in different provinces of Iran was performed using RAPD-PCR method. The gram-positive cocci were first obtained from the kidney tissues of diseased trout. The bacterial isolates were grown on brain heart agar (BHI) and were then identified by a specific PCR method. The recovered gram-positive cocci strains were identified as L. garvieae by producing a 1100bp PCR product Then bacterial genotyping were processed with RAPD-PCR using two distinct random primers: P5 and M13. The RAPD-PCR results showed that primer P5 was able to produce maximum of 3 bands and 4 banding patterns, but primer M13 produced maximum of 7 bands and 5 banding patterns. Accordingly, the phylogenetic tree of the RAPD-PCR product using UPMGA software and using the primer P5 included these strains in 2 major clusters and 4 genetic groups, but using the primer M13 included these strains into 2 major clusters and 5 genetic groups. The results of this study indicate that although there are some phenotypic similarities between isolates of L. garvieae in different regions of Iran, these isolates have noticeable genetic differences. Further studies are need to clarify whether such genetic diversity of the isolates are important for bacterial severity and prophylactic vaccination.

In general, the relationship between zooplankton and bacteria is important to increase the productivity of live food production. The present study was done with the objective to investigate the predominant bacteria in Daphnia pulex (Cladocera) and Apocyclops dengizicus (Copepoda) fed with manure (chicken and sheep manure at rates of 1:1), vegetables (Fenugreek + Thymus + Savory at rates of 1: 1: 1 weight ratio) and Oscillatoria africanum, the effect of culture medium on zooplankton density and medium BOD and COD. The results showed that different diets had a significant effect on the D. pulex and A. dengizicus density, bacterial populations and biochemical medium properties (BOD and COD). The dominant bacteria in the mediums enriched with manure and vegetables for D. pulex were Acinetobacter sp. and in the medium containing O. africanum, Aeromonas sp. was dominant. In the A. dengizicus cultivation medium enriched with manure, vegetables and O. africanum, the Neisseri sp., Enterobacteria sp. and Alcaligenes sp. were dominant, respectively. Maximum microbial population in medium was measured in D. pulex fed manure (11×104 cells/ml) and A. dengizicus fed with O. africanum (12×103 cells/ml). The highest density of D. pulex (289±11.9) and A. dengizicus (188±19.2) were calculated in the medium enriched with O. africanum, while the least density was counted when manure was used. BOD and COD showed maximum amount in D. pulex and A. dengizicus fed with vegetables (101 and 298 mg/l, respectively). The results showed that there was no significant correlation between D. pulex density and bacterial population, but there was a significant correlation between bacterial populations and A. dengizicus density. Also, there was a significant correlation between zooplankton density (D. pulex and A. dengizicus) and biochemical medium parameters (BOD and COD). In general, it can be concluded that in order to achieve the highest density of D. pulex and A. dengizicus, the use of culture media containing O. africanum has a higher efficiency. Also, zooplankton species and diet used during breeding period affect the type of bacteria and their population density.

Nowadays, mitigating the effects of mycotoxins is an important issue in aquafeed industry. In the present study, 135 common carp fingerlings with an average body weight of 15±1.5 g were reared for 12 weeks in three distinctive treatments (control group, 400 ppb aflatoxin B1 and 400 ppb aflatoxin B1 400 ppb along with rosemary and thyme powder). At the end of the trial, hepatopancreas, intestine and blood samples were taken for determination of alkaline protease, lipase and amylase activities and some blood indices. Results revealed that diets contaminated with aflatoxin B1 and the diet supplemented with rosemary and thyme for 12 weeks did significantly affect alkaline protease activity of hepatopancreas and intestine activity, RBC count, hemoglobin, neutrophil and lymphocyte (P≥0.05), however, did not significantly affect intestinal lipase and hepatopancreatic amylase activity along with other hematological indices (P<0.05). The highest intestinal alkaline protease and amylase activity were observed in fish fed diet containing 400 ppb aflatoxin. In addition, the lowest hepatopancreatic and intestinal alkaline protease, lipase and amylase activities belonged to those fish received aflatoxin contaminated diet supplemented with rosemary and thyme (P<0.05). It could be concluded that including rosemary and thyme in diet contaminated with aflatoxin B1 could mitigate the deteriorative effect of the mycotoxin on intestinal alkaline protease and amylase activities along with RBC count, hemoglobin content, neutrophil and lymphocytes of common carp fingerlings.

Lecithin as a source of phospholipid are considered to increase the growth efficiency, reproduction and evolution of fish and crustaceans. Due to Insufficient synthesis of phospholipids in the aquatic this research was performed to investigate the effect of enrichment of Artemia franciscana nauplii and adults with soybean lecithin on proximate and lipid class composition. In the first stage, 200,000 nauplii / liter of water was enriched with soyabeen lecithin (74.42% phospholipid) for 24 hours. Enrichment emulsion (with a ratio of 10:1 ml: g of water and powdered lecithin) was added to enrichment containers at 3 ml for 2 times zero (beginning of enrichment) and 12 hours. To enrich adult Artemia (14 days and length 8.50 mm) with a density of 3000 Artemia per liter similar the first step the enrichment emulsion at 3 ml was used at 0 and 3 hours. After 6 hours, the enriched Artemia was washed by sieve and harvested. The results showed that there was no significant difference in the amount of dry matter and crude protein between lecithin-enriched Artemia nauplii and adults and unenriched Artemia (P> 0.05). Enrichment with lecithin in both steps of nauplii and adults, causes a significant increase in the amount of crude lipid (in nauplii from 17.62 to 21.39 and in biomass from 16.05 to 19.69 %). In terms of lipid classes, phosphatidylcholine, phosphatidylserine + phosphatidylinositol was significantly higher in lecithin-enrichednauplii than unenriched nauplii (P< 0.05). In enriched Artemia adult, levels of phosphatidylethanolamine and lysophosphatidylcholine were significantly different than control groups. Also enrichment of Artemia nauplii and adults with soybean lecithin significantly increased total polar lipids (12.96% and 43.72%) and triglycerides (53.35% and 79.9%). In conclusion, it can be stated that using 0.6 g L-1 soybean lecithin increases phospholipid groups as well as total fat in Artemia nauplii and adults.