نشریه علوم و فنون شیلات
سال دوازدهم شماره 1 (پیاپی 41، زمستان 1401)

The significance of mangrove species in the world is undeniable and planting artificial mangrove forests is a desirable solution to preserve mangroves. The mangroves provide us with superior ecological services and one of their main services is the bioremediation of heavy metals. Hence, this study aimed to assess the effects of artificial mangroves of Velayat Park of Bandar Abbas on the contamination, adsorption pattern and ecological risk of heavy metals in the sediment samples. Thirty samples were collected from two paralleled sampling sections included those without mangroves and containing mangroves. Each sampling area consisted of upper, middle and lower sections. After drying samples using an oven, the dried sediments were sieved by a 63-micrometer sieve and digested by nitric and hydrochloric acid mixture. The concentration of As, Cu, Fe, Ni, Pb, V, and Zn was determined using ICP. The studied factors suggested a high level of ecological risk for as and Pb and the highest risk was observed in the samples without mangroves and a lower risk was reported for samples containing mangroves. Comparing the results with sediment quality guidelines and other studies indicated a dangerous concentration of As. Pearson correlation coefficient values exhibited that artificial mangroves have significantly affected the adsorption pattern of heavy metals (p-Value < 0.05). The principal component analysis (PCA) showed that As and Pb are dominantly derived from oil products leakages and industrial sewages while Cu, Fe, Ni, V and Zn are predominantly derived from natural and geological sources.

Today, the continuous release of environmental pollutants into aquatic ecosystems has made these environments extremely vulnerable and turned them into a storage sites for these toxic substances, so it is necessary to investigate the effects of these pollutants on aquatic life. The present study was conducted with the aim of determining the toxicity of silver nitrate and observing the behavioral changes of Litopenaeus vannamei during its exposure. To determine the toxicity, the standard method of OECD was used. At first, the viability and survival of Litopenaeus vannamei were checked after two weeks of acclimatization to laboratory conditions, then by conducting preliminary tests, the actual lethality values ​​of silver nitrate were obtained. In order to determine the median lethal concentration, shrimps were exposed to concentrations of  0.025, 0.05, 0.1, 0.2, 0.4 and 0.8 mg/L of silver nitrate for 96 h and their mortality were recorded daily every 24 h. The LC50, LOEC, NOEC and MATC were calculated based on shrimp mortality. During the viability and survival test, no mortality were observed up to 96 hours, and the survival rate of shrimps was 100%. The value of LC50, NOEC, LOEC and MATC were determined as 0.084, 0.02, 0.025 and 0.0084 mg/liter, respectively. In different concentrations of silver nitrate, shrimps showed behaviors such as abnormal swimming, fast movements of swimming legs, coming to the surface of the water, twisting the body around itself and eventually losing balance.

Bacteria are used directly by zooplankton as a food source. The purpose of this study is to use straw as a substrate for the proliferation of bacteria in geomembrane pools and its effects on the production and biochemical compositions of Artemia. One week before Artemia culture, the pools inoculated with Dunaliella sp. and straw (particles less than 200 microns) as follows: treatment 1= geomembrane pool containing Dunaliella sp. (one week of algae cultivation), treatment 2 = geomembrane pool containing Dunaliella sp. and 0.5 grams per liter of straw (one-week algae cultivation and adding straw from the second week), treatment 3 = geomembrane pool containing Dunaliella sp. and 0.5 g/l of straw (algae cultivation and adding straw from the first week) and treatment 4= geomembrane pool containing 0.5 g/l of straw (adding straw from the first week). Artemia was cultured for 18 days and fed based on a turbidity depth of 15 cm. The highest growth rate was observed at the end of day 18 in treatment 3 (P<0.05). The highest amount of protein was obtained in treatment 1 (P<0.05). The highest amount of biomass was observed in the control and T3 groups (P<0.05). The presence of straw in Artemia pools decreased EPA fatty acid by 5-7 times less than the control (P<0.05). Artemia can grow while feeding on environmental bacteria. Applying straw in Artemia cultivation can lead to an increase in PUFA fatty acids with 18 carbon chains.

Omega-3 polyunsaturated fatty acids (ω-3PUFAs) have gained increasing interest in recent years due to their beneficial effects in maintaining heart health and regulating blood pressure, improving brain function, strengthening memory, and reducing depression. Fish and algae are known as the main sources of ω-3PUFAs. In the meantime, extracting fish oil from less-exploited species or fish waste not only creates higher added value, but also reduces environmental pollution caused by the process of disposal of fishery waste. In this study, the most common methods of oil extraction from marine sources, such as solvent-based methods (Soxhlet, Bligh and Dyer, and Folch Methods), supercritical fluid extraction (SFE) and enzymatic hydrolysis, along with their advantages and disadvantages, were investigated. Among them, Soxhlet extraction provides a high yield of lipids; Of course, choosing the right solvent is the most important factor in the effective extraction of lipids. However, continuous heating at the boiling temperature could lead to lipid oxidation and degradation of heat liable compounds. Therefore, development of alternative extraction and purification methods based on the use of green technologies and the sustainability principles, avoiding the use of organic solvents and high temperatures, is needed in order to produce omega-3 polyunsaturated fatty acids of higher purity and quality. Supercritical fluid extraction with environment-friendly solvents and enzymatic hydrolysis are the most promising green technologies for extracting fish oil, whereas pressurized extractions are suitable for extracting microalgae oil.

The aim of this study was to extract astaxanthin from banana shrimp (Fenneropenaeus merguiensis) using ultrasound assisted method and to investigate its antioxidant properties. Extraction with organic acetone solvent was performed by soaking on a magnetic stirrer at room temperature for 5, 10, and 15 minutes, as well as neutralization tests of DPPH and ABTS free radicals. Fe3+ ion reduction was carried out. One-way analysis of variance was used for statistical analysis of the data. The best astaxanthin yield was 79.5±0.012 µg/g in the conditions of 20 minutes of magnetic stirrer at ambient temperature with 400 watts of ultrasound for 10 minutes, and the lowest average yield was observed in the condition of 15 minutes of magnetic stirrer at ambient temperature with 400 watts of ultrasound with a time of 15 minutes with a value of 69.3±0.049 µg/g. The findings of all three ABTS, DPPH, and Fe3+ ion reduction tests revealed that the settings were 20 minutes of magnetic stirrer at ambient temperature followed by 10 minutes of 400 watts of ultrasound. In summary, the results of this study demonstrated that using ultrasound for a shorter period of time has a better effect, while increasing the time diminishes the yield and antioxidant qualities.

In this study, the possible impact Asian sea bass fish (Lates calcarifer) cages culture on the population structure of phytoplankton in the coastal waters of Qeshm Island.Water sampling was done monthly for a period of six months in three stations from October 2018 to March 2019.The results showed that the mean Variations of total abundance of phytoplankton at the location of fish cages culture compared to the Reference station had a significant increase (P <0.05). At the location of cages culture, the Trophic status level was high (<5), the risk of eutrophication status (<4) and the value of trophic efficiency coefficient were high. According to the analysis of Simper test, Among the Forty-one genera identified, Noctiluca sp. with a relative abundance of % 82.37, contribution rate of 21.8% with high algal bloom at the location of cages in autumn season and then the genera Chaetoceros sp., Nitzschia sp. and Coclodinium sp. with a relative abundance of less than 10 percent in differentiating the population structure of phytoplankton have played a significant role in the dissimilarity of the population structure of phytoplankton between stations In general, in this study, the effects of fish farming activities on the population structure of phytoplankton are ineffective, but it causes the abundance of some species, available nutrients, increases the trophic level, and the probability of harmful algal blooms in the location of the cages culture.

In the present study, the goldfish kisspeptin peptide was synthesized using the solid phase synthesis method according to the nucleotide sequence of the goldfish (Carassius auratus) kiss1 gene. Next, an acetyl group was added to the amino group of Tyr1 to increase the biological activity. The synthesized peptide (referred to as ACKiss1) was purified by RP-HPLC and its structure was confirmed using electrospray ionization (ESI) mass spectrometry. To determine the biological activity, ACKiss1, native Kiss1 and commercial GnRH hormone were injected to goldfish, some important parameters of the reproductive physiology were studied. Kiss1 and ACKiss1 were injected with a dosage of 100 μg/kg fish body weight and GnRH was injected with dosages of 100 and 200 μg/kg body weight. 6 hours after injection, blood was taken from the caudal vein and sex hormones were measured in plasma. 24 hours after injection, reproductive indices were measured in a series of fish. In another series of fish, 24 hours after injection, ovarian and brain tissues were separated for histological studies and expression of the reproductive-related genes (cyp19b, gpr54a, and kiss1). The results revealed that significant changes in biochemical parameters and gene expression were recorded in both brain tissue samples and ovarian tissue in ACKISS1 treatment. It was also found in ovarian histology that under the influence of kisspeptin and GnRH, the number of mature oocytes increased significantly.