فصلنامه فیزیولوژی و بیوتکنولوژی آبزیان
سال دوازدهم شماره 2 (تابستان 1403)

There are widespread concerns about the potential toxic effects of microplastics as emerging pollutants. The current research investigated the impact of polystyrene nanoplastics on the growth performance, survival rate, liver enzymes activity and the immune gene expression of IL1 and IL8 genes in zebrafish (Danio rerio). Fish were divided into four treatments and fed with diets containing 0 (control), 100 (treatment 1), 500 (treatment 2) and 1000 (treatment 3) mg/kg diet for one month. The present study results showed that weight gain (WG) and specific growth rate (SGR) were affected by the experimental treatments, and with increasing concentration of polystyrene nanoplastic, they decreased significantly (P<0.05). The best food conversion ratio (FCR) was obtained in control and treatment 1 (P<0.05). No mortality was observed through different treatments. The highest activity of alanine aminotransferase) ALT(, alkaline phosphatase) ALP(, and aspartate aminotransferase )AST( was observed in treatment 3 (P<0.05). The highest level of IL1 and IL8 gene expression were measured in treatment 3 and the lowest level was seen in control (P<0.05). In conclusion, the results of this research showed that a diet containing polystyrene nanoplastics had a negative effect on the growth (WG and SGR) and health indicators of the fish and the greatest disturbance in the growth and health of fish were observed in high concentrations.

Common carp (Cyprinus carpio) with densities of 6, 12, 24 and 48kg/m3 (D1, D2, D3 and D4, respectively) were stocked in biofloc environment with acute hypoxia stress in order to investigate the physiological response of fish. At the first stage, the fish were kept in biofloc conditions for 28 days, and then in the second stage of the experiment, the fish were separately divided in 12 tanks with a water volume of 25 liters (4 treatments × 3 replicates) with the same biological conditions, and the only variable was the stocking density of fish. Increasing stocking density in D4 treatment significantly increased WBC, RBC, hemoglobin and hematocrit, but decreased lymphocytes and liver enzymes (P<0.05). Stocking density significantly increased total Immunoglobulin, lysozyme and ACH50 were observed in D1and D2 treatments (6 and 12k/m3) (P<0.05). The stress index had a significant increase in D3 and D4 treatments (P<0.05). Stocking density in D1 and D2 treatments significantly increased superoxide dismutase enzyme and decreased malondialdehyde enzyme (P<0.05). In general, the storage density between 6 and 12kg/m3 is recommended to control the hypoxia stress in the biofloc environment, so that the problem can be solved within one to two hours.

Green synthesis of nanoparticles has attracted a lot of attention due to economic and environmental benefits compared to common chemical synthesis methods. The aqueous extract of brown macroalgae Sargassum ilicifolium was used for the green synthesis of zinc oxide nanoparticles. Biosynthesized nanoparticles were identified by color change, UV-Vis spectroscopy, FT-IR, TEM, SEM and XRD. The results showed that the formed nanoparticles were spherical and crystalline with a size range between 15.1 to 27nm. Antibacterial activity of biosynthesized zinc oxide nanoparticles was investigated by MIC and MBC method against Staphylococcus aureus and Escherichia coli bacteria and the results showed that biosynthesized zinc oxide nanoparticles had a significant antibacterial effect against the tested bacteria. Finally, this study shows that the green synthesis of zinc nanoparticles from marine macroalgae can be an effective, sustainable and environmentally friendly method to produce zinc oxide nanoparticles with antibacterial properties.

The Persian Gulf is a semi-closed inland sea with specific ecological conditions, and the level of oil pollution in it exceeds the global average acceptable for the marine environment. Echinoderms, due to their benthic nature, are more exposed to sediment pollution. This study was conducted in the intertidal zones of Bushehr province, including the shores of Shaghab, Owli, Shirino, Nay-Band, the T-pier and the Northern Khark Island, to determine the level of contamination in sediments and the tissue of the sea urchin Echinometra mathaei. Sampling was carried out in two seasons, winter and summer (2014-2015). In the laboratory, the samples were analyzed for the type and concentration of polycyclic aromatic hydrocarbons (PAHs) using chromatography and GC-MS. The highest concentration of PAHs in the sediments at the T pier in Khark was found to be naphthalene (913.7ng/g dry weight) in the winter, while the highest concentration of PAHs in the tissue was measured as phenanthrene (371.5ng/g dry weight) in the summer. No significant difference was observed between the levels of PAHs in sediments and tissues (P>0.05). The trend of PAH accumulation in sediments and tissues was increasing. The level of PAHs in sediments across all study areas (3059-441ng/g) was higher than the global standards set for sediments (197µg/kg), indicating greater pollution in the examined areas. A comparison of pollution accumulation in the tissues of the sea urchin with other aquatic species revealed higher PAH levels in the tissues of benthic species. This finding is due to the habitat and feeding type of these organisms, highlighting the importance of this species and the need for environmental toxicological studies on it.

In this research, the anesthetic effects of peppermint essential oil with concentrations of 100, 150, 200, 250 and 300 mg/L and its comparison with concentrations of 20, 30, 40, 60, 80 and 100 mg/L of clove essential oil were evaluated in rainbow trout. 132 fish with an average weight of 23.31±1.27g were used for anesthesia experiments. The induction time of anesthesia using peppermint essential oil varied from 1.69 to 4.81 minutes among different concentrations. In the case of clove essential oil, this time varied from 0.82 to 2.51 minutes in different concentrations. Recovery from complete anesthesia in both anesthetics significantly increase with increasing concentration of the anesthetic. The recovery time from complete anesthesia in the case of peppermint essential oil was from 2.50 to 5.55 minutes and in fish anesthetized with Clove essential oil varied from 2.96 to 3.87. Based on the ideal criteria of induction of anesthesia (less than 3 minutes) and recovery from anesthesia (less than 5 minutes), it is recommended that the most suitable concentration of peppermint essential oil to anesthetize rainbow trout in the tested weight is 200mg/L and the most suitable concentration of clove essential oil is 30mg/L.

This research was conducted with the aim of identifying and survey of oogenesis and spermatogenesis of the dominant bivalves of the Karun River seasonally. Bivalves, after catching and transferred to the laboratory, were bioassayed using valid identification books and keys. Gonads were examined histologically after dissection and isolation and tissue passage. The results showed the presence of the invasive alien species Sinanodonta woodiana (a bivalve clam from the Unionidae family) that for the first time was isolated and identified from the muddy sediments of the Karun River only in spring. The results of the histological studies of the gonads showed that the individuals of this species were heterosexual. Ovary was asynchronous type because at any time all types of female sex cells (oogonia, pre-vitellogenic oocytes, vitellogenic oocytes) were visible in the ovaries. Also, due to the presence of a large number of sperms in the lumen of the testicular follicles, intense spermatogenesis and the male gonad seemed developed and mature in this season.

After catching, aquatic animals undergo chemical, microbial and sensory changes, which cause them to spoil and reduce the shelf life of the product. The purpose of this study was to use edible chitosan coating containing the alcoholic extract of Nannochloropsis sp. on the shelf life of Metapenaeus affinis. For optimization, different concentrations of algae extract (0, 1.5 and 3%), temperature (-10, -3 and 4°C) and storage time (0, 7 and 15 days) were considered as independent variables. Based on the output of RSM software, 15 treatments were selected, and variance analysis was used to determine the suitability of the obtained models. Peroxide value (PV), thiobarbituric acid (TBA), total volatile nitrogen bases (TVB-N), free fatty acids (FFA), total aerobic bacteria (TVC) and color changes (L*, a*and b*) were investigated. Based on the results, the amount of microbial, chemical and indicators of shrimp fillet decreased significantly with the increase in the concentration of algae extract compared to the control group (P<0.05). On the seventh and fifteenth days of storage, the ninth and twelfth treatments showed the lowest bacterial load with 3.22±0.64 Log CFU/g and 4.60±0.65 Log CFU/g (P<0.05). The increase in extract concentration and temperature caused the increase of a* and b* indices and the decrease of L* color index. The percentage of fat and weight yield of shrimp fillet increased significantly with the increase in extract concentration (P<0.05). Based on the results of quality indicators, shrimp fillet at -10°C and 3% extract concentration was favorable for human consumption. According to F-value, in all indicators, temperature was more influential compared to time. The proposed formulas for each index were able to predict the quality changes of shrimp fillet.