AQUATIC PHYSIOLOGY AND BIOTECHNOLOGY
Year:2020 | Volume:8 | Issue:2|Papers Count:9

To study the spawning migration of five-year-old reproductive and non-reproductive female kutum, Rutilus frisii kutum, the trace elements of Sr, Ba, Ca and the ratios of Sr: Ca, Ba: Ca and Sr: Ba were examined in their otoliths using ICP-MS. Water and fish samples were collected from the southern part of the Caspian Sea in reproductive season (February and March) of kutum. The concentration of Sr in Caspian Sea was twice than river while there was insignificant difference between two habitats in terms of Ba levels. Statistical comparison between reproductive and non-reproductive female kutum revealed small difference in the concentration of otolith Sr, but showed significant difference in Ba: Ca ratio. Differences in Ba: Ca ratio could be the result of fish migration towards the coastal zones over reproductive season and feeding of nonreproductive individuals in estuarine areas. Results indicated that microchemical analyses of otolith can be used as a valuable tool for differentiate reproductive and non-reproductive individuals. By means of elemental content relative to calcium, two types of fish could be differentiated for better understanding the movement pattern of fish broodstock, which could be completed with data from the other methods like tagging.

In order to predict the environmental effect of biosynthesized magnetic iron oxide nanoparticles (magnetite or bio-Fe3O4) using marine green algae Ulva flexuosa in aquatic ecosystems, its toxicity was assessed on the early life stages and larvae of zebrafish, Danio rerio as an aquatic model. For this purpose, 10 fertilized eggs of zebrafish were exposed to serial concentrations of bio-Fe3O4 nanoparticles (0, 10, 50, 100, 200 and 500 mg/L) in 6 well plates in 6 replicates. After 12, 48, 72, 96, 110 and 134h samples were assessed. Results showed that the percentage of hatching rate and the larval survival rate decreased with increasing exposure time and concentration of magnetite nanoparticles (P<0. 05). After 48h of exposure, in the highest concentration (500mg/L), the hatching rate of fish decreased to 36. 6% (48 h LC50 = 638. 2 mg/L) and after 134h of experimental periods, the survival rate of larvae reached to 43. 3% (134 h LC50 = 645. 4mg/L). The mean of all skeletal malformations in zebrafish would be significant with an increase in a dose-and time-dependent pattern during the exposure to nanoparticles and in the highest dose (500mg/L) reached 13. 3% (P<0. 05). It seems that the toxicity of bio-Fe3O4 nanoparticles affected by their particle size (13. 8nm) and potentially toxic kinetic actions of particles at the nanoscale.

The use of natural antifouling agents is a new and suitable approach to solve the worldwide biofouling problem. In this study, anti-micro algal and antifouling activity of a series of n-hexane, ethyl acetate and methanol extracts from four sections of sea cucumber Holothuria leucospilota (body wall, gonad, digestive tract and respiratory tree) were investigated. Anti-microalgal assay against two microalgae species Chlorella vulgaris and Isochrysis galbana was conducted to determine the minimum inhibitory concentration (MIC) for each extract. The best extracts were added to resin epoxy and applied on fiberglass panels (10×10cm). All panels were immersed in the Persian Gulf (Bandar-e-Gorzeh) for three months. Results indicated that ethyl acetate extract of the body wall had the best inhibitory activity against I. galbana, with MIC of 0. 062 mg/mL. Based on field results, the panel coated with 4% ethyl acetate extract from body wall added to resin epoxy had the lowest final weight (123. 33± 8. 32g) and lowest fouling cover percentage (57. 8%) among all panels after three months (P<0. 05). Regarding the high antifouling activity of ethyl acetate extract from the body wall of sea cucumber H. leucospilota, its use as a potential alternative to commercial biocides in antifouling coats is suggestable.

An 8-week experiment was conducted to evaluate the effect of different carbon sources and protein levels on mucus immune parameters, hepatic enzymes and intestine lactic acid bacteria loading in biofl oc system of common carp (Cyprinus carpio) juvenile in intensive culture. Fish fed the feed containing 20 or 30% crude protein including two groups in clear water conditions with no biofloc, two biofloc groups given a molasses as additional carbon source (M), two biofloc groups given rice bran (RB) and two biofloc groups given mixture of molasses + rice bran at equal weight ratio (M+RB). At the end of trial, mucus immune parameters (lysozyme activity and total immunoglobulin), hepatic enzymes (LDH, AST, ALT, ALP) and intestine lactic acid bacteria loading were investigated. The results showed that significant improvements in immune parameters were observed in fish fed 30% dietary protein and reared in biofloc condition (P<0. 05). Hepatic enzymes and lactic acid bacteria loading significantly improved in fish fed 30% dietary protein and reared in M and M+RB biofloc than control group (P<0. 05). In conclusion, using mixture of M+RB as carbon source associated higher protein can be improved immune response, metabolic enzyme and lactobacillus loading in intensive farming of common carp.

In this study, the role of probiotic and halophilic bacteria were studied in biofloc system using different carbon sources including corn starch (treatments 1 and 4), beetroot molasses (treatments 2 and 5), rice-bran (treatments 3 and 6), with sugar cane vinasses (used in all treatments) at presence of commercial probiotics (Bacillus subtilis and Bacillus coagulans) (treatments 1, 2 and 3) and combination of probiotics and halophylic bacteria (treatments 4, 5 and 6) at salinity of 60± 5g/L during 42 days. Minimum concentrations of nitrite and nitrate were recorded in treatment 6 and lowest ammonia in treatment 1. The highest floc volume were produced in treatments 2 and 5 (41-48mL/L). In terms of nutritional value, significantly higher protein (2025%) and ash (75-80%) were detected in treatments 2, 3, 5 and 6. But significantly higher carbohydrate (64%) was detected in treatments 1 and 4. Fatty acid analysis of the bioflocs showed that treatments 2 and 5 had highest PUFA n-3 (32%) and treatments 3 and 6 had significantly higher MUFA (22-25%). Results of this research showed that different carbon sources had significant effect on biofloc quality, but the use of probiotics separately or in combination with halophilic bacteria had no significant effect on biofloc quality.

A high rate of pesticide use has increased the concern regarding the toxic effects of pesticides. In this respect, the genotoxic effects of carbamate in the liver and the gill of Aphanius kavirensis have been investigated. The experiment was run for up to nine days. The specimens were exposed to 0, 0. 5, 1 and 1. 5 mg. L-1 of carbamate and the gill and liver of the specimens were sampled at 1, 3 and 5 days after the start of the experiment. The results showed that the pesticide concentration had no significant effect on DNA breakage (P>0. 05). But, exposure duration had a significant effect on DNA breakage (P<0. 05). There were dissimilar trend in DNA breakage of the gill and liver. The highest rate of DNA breakage in the gill was found at day 1 and in the liver at day 5. A decrease in the percentage of DNA breakage was found in two organs after day 9 indicating that there was a mechanism in both organs to recover the damaged DNA. In conclusion, the highest rate of DNA breakage in this species was found in initial stages of exposure to the pesticide and the rate of the breakage may be decreased or disappeared over time.

This study was conducted to evaluate water quality impacts on phytoplankton community and nutritional status of the Gomishan shrimp ponds. During the breeding season (May-October 2016), water was sampled using one-liter dark bottles from 6 ponds and in each pond, three stations, near the entrance, the middle and near the outlet. At the sampling site, some physical and chemical factors of water were measured and recorded, including: temperature, salinity, pH, dissolved oxygen (DO), turbidity and EC. Water Samples were transferred to the laboratory for measuring nitrate and phosphate, as well as the identification and counting of phytoplankton. Total of 23 genus belonging to 6 phylum recorded for the ponds. Bacilloriophyta and Dinophyta phylums dominated the phytoplankton community in June. There was a significant difference in phytoplankton phylum abundance among months of study period (P<0. 05). The results showed that all recorded environmental factors were in an optimal range, while DO and salinity variations were considerable. Pearsons test analysis revealed that there is significant correlation between phytoplankton abundant and environmental factors in the study period.

Siberian sturgeon is a suitable species for using in aquaculture industry. The purpose of this study was to investigate the effect of glutamine on growth and blood and immunity indices of Siberian sturgeon fingerling and to determine the optimal amount of glutamine in rearing conditions. This study was performed on 126 fish with a mean weight of 45. 71± 7. 56g in six treatments (control, 5, 10, 15, 20 and 30g glutamine/kg diet) and three replicates during 8 weeks. The results showed that there was no significant difference in growth factors (P>0. 05). However, final weight, final length, the percentage of increasing body weight, feed conversion ratio, specific growth factor and daily growth rate were higher in fish fed the diet containing 30g glutamine/kg diet compared to other treatments. The highest obesity coefficient was observed in fish fed the diet containing 5g glutamine/kg diet. Also, there was no significant difference in red and white blood cell count, hemoglobin, hematocrit, MCV, MCH, MCHC, neutrophil and lysozyme (P>0. 05), but lymphocytes, monocytes, eosinophils, IgM and total immunoglobulin were significantly different (P<0. 05). Glutamine had no significant effect on most of the blood parameters of Siberian sturgeon, but an increase in immunity parameters such as lymphocytes, monocytes, total immunoglobulin and IgM was observed. It seems that the addition of glutamine to the basal diet is not necessary in this age and culture conditions and the basal diet supports the needs of fish.

In this study, the effects of salinity and light intensity stress on the fresh weight, some of pigments, protein and carbohydrates has been studied in green algae Scenedesmus obliquus. For salt stress, BG11 culture was used with 0, 100, 200 and 300mM NaCl concentrations and for light intensity stress a week after subculture, algae were exposed to 114 μ mol. m-2-1. s light intensity for 0, 2, 4 and 6 days. Samples were harvested 14 days after subculture and fresh weight of Scenedesmus decreased under both stress. The lowest fresh weight was observed in 300 mM NaCl and six days light intensity treatment and controls were the most. Also the amount of carotenoids severely decreased under these stress. The most of β-carotene and lutein were observed in the control samples and the lowest of them in 300 mM of salt concentration and six day treatment of light intensity. The amount of astaxanthin increased under both stress. These results showed that salinity in applied concentration and also light intensity in different levels significantly reduced growth but increased astaxanthin content. In addition, growth reduction and other parameters were indicative low resistant and incompatibility of this species of algae to salinity and light intensity stress.