فصلنامه بوم شناسی آبزیان
سال سیزدهم شماره 1 (پیاپی 48، تابستان 1402)

In this study, γ-Fe2O3 magnetic nanoparticles were synthesized via solvothermal method and after coating a silica layer (SiO2), TiO2 nanoparticles were used as a core to grow on the outer surface to get γ-Fe2O3@SiO2@TiO2 nanocomposite. In order to increase the photocatalytic efficiency, the obtained nanocomposite was doped with different metals such as copper and nickel. Different techniques such as XRD, SEM and FTIR were used to characterize and determine the properties of the produced nanoparticles. Antibacterial activities of the doped magnetic nanocomposites on the gram-positive S. aureus and gram-negative E.coli strains were investigated by disc diffusion and minimum inhibitory concentration methods. The results obtained from the inhibition amount of the bacterial growth showed that the γ-Fe2O3@SiO2@TiO2 nanocomposite has high antibacterial properties which could be increased by doping with copper and nickel metals. The amounts of 15 mg were selected as the minimum inhibition amount of the growth of the bacteria for the two photocatalysts consisting of copper and nickel. It can be concluded that the synthesized nanocomposites with photocatalytic properties have a suitable potential to remove harmful bacteria from the aquatic environments.

The widespread use of produced metal oxide nanoparticles has raised major concerns about their impact on human health and aquatic organisms. The aim of the present study was to determine the effects of iron oxide nanoparticles (FeO) and microalgae Spirulina platensis on the gills of gray mullet (Mugil cephalus) in four groups, i.e., first or control (without iron oxide nanoparticles and algae extract), second (15 mg/kg iron oxide nanoparticles), third (300 mg/kg algae extract) and fourth (15 mg/kg iron oxide nanoparticles and 300 mg/kg algae extract) during three periods of 3, 14 and 28 days. For this purpose, 72 specimens of gray mullet were acclimated to the experimental condition and exposed to different concentrations of iron oxide nanoparticles and algae extract in the mentioned groups and time periods. Then the gill tissue of each fish was sampled and the slide tissues were prepared. The gill tissue complications were hyperplasia, hyperemia, secondary lamella shortness, secondary lamella fusion, lamella deformity, epithelial detachment, and lamella clubbing. The fourth group showed more complications in all three time periods, and after that, the second and third groups showed more respectively. The more exposure time caused more tissue complications and the highest number of complications was observed on day 28. Also, algae had no effect on reducing tissue complications in fish, while it caused tissue complications but with less intensity. Based on the results, iron oxide nanoparticles can endanger fish health over time. Therefore, further studies are needed to evaluate its potential toxic effects.

The filtration rate is one of the physiological indices in bivalves that indicates the degree of the effectiveness of the filtration function in exposure to contaminants. In this study, the changes in filtration rate of Dressina poly morpha were investigated after 7 and 14 days of exposure to silver nanoparticles. Bivalves were removed from the natural environment and transferred to the laboratory. The distribution of nanoparticles in water tanks was tested with the DLS device. Bivalves were exposed to concentrations of 0.25, 2.5 and 25 ppm of nanoparticles for 14 days. The results showed the highest filtration rate for the control group (96 ± 47.74 ml min-1 g-1DW). On day 7, the highest filtration rate was observed in the first treatment (88.58 ± 64.38 ml min-1 g-1DW) and the lowest filtration rate was observed in treatment 3 (47.67 ± 11.81) ml min-1 g-1DW), no significant difference was observed in the filtration rate betwen first treatment and control (P >0.05), but the filtration rate in the third treatment was significantly (P <0.05) lower than that of the other treatments and the control group. Moreover, the filtration rate on day 14 showed similar differences to day 7, but more significant. Therefore, it can be concluded that filtration rate changes are a good indicator for nanoparticles contamination.

Marine plants are good source of natural antioxidant compounds. Mangroves are a group of salt-tolerant marine plants of intertidal areas with numerous medicinal properties. In the present study, phytochemical analysis (steroids, alkaloids, phenols, flavonoids and tannins) and antioxidant properties (total phenolic content, DPPH free radical scavenging activity, reduction power and metal chelating activity) of methanolic extract of leaves, stem bark, and roots of mangrove species Avicennia marina was investigated. The mangrove samples were collected from the shores of Gwater Bay in the southeast of Sistan and Baluchestan province. Phytochemical analysis showed that all the tested compounds were present in the extract of mangrove leaves, except alkaloids. While in the stem bark extract, only phenolic compounds, flavonoids and tannins were observed and alkaloids and steroids were not detected. Alkaloids, phenols and flavonoids were discovered in the root extract. The assessment of the antioxidant properties showed that among different parts of mangroves, the highest amount of phenol (6.28 mg gallic acid/ g extract), free radical scavenging (59.18 %) and iron ion reduction power (absorbance at 700 nm: 0.37) was found in the leaves extract. Contrary to these two indicators, the highest amount of iron chelating activity (absorbance at 562 nm: 0.84) was found in mangrove root extract. The results of this research showed that different parts of the mangrove plant, especially its leaves, can be considered as a potential source of natural antioxidants.

Polyaromatic hydrocarbons (PAH) with a benzene ring are petroleum compounds and are known as the most important cause of environmental pollution. Phenanthrene and anthracene are PAHs found in the aquatic environment. In the present study, the effect of these two substances on a freshwater algae, Spirulina platensis, was investigated at biochemical levels. Algae mass cultivation was performed in laboratory conditions in nine treatments and 27 repetitions of anthracene (5, 25, 50, 250 mg/l) and phenanthrene (10, 50, 100, 500 mg/l) for 72 h. A control treatment with no anthracene and phenanthrene was also considered. The amount of malondialdehyde (MDA) in the treatment of phenanthrene and anthracene increased compared to the control treatment, which was significant at the 5% level, but the amount of MDA in the treatment of phenanthrene at a concentration of 10 mg/L did not show a significant difference (P>0.05). Sugar content showed a significant difference except in the concentration of 10 mg/liter of phenanthrene (P<0.05). Proline content increased significantly in response to both hydrocarbons (P<0.05), There was a significant increase in proline in both anthracene and phenanthrene treatments compared to the control group at a probability level of 5%. Catalase activity showed significant changes between the treatments compared to the control (P<0.05). The amount of total protein significantly increased in phenanthrene stress and significantly decreased in anthracene stress in all concentrations compared to the control group (P<0.05). The results showed that both hydrocarbon substances at different concentrations had significant effects on the biochemical characteristics of spirulina algae.

The physical, chemical and biological characteristics of rivers are gradually changed from upstream to downstream of the river, and one of the obvious consequences of these changes is the creation of limited and specific reaches along the river for fish species. In the present survey, the Jajroud river was sampled and surveyed from the upstream tributaries to downstream using the Huet classification method. In this study, 783 specimens of fish belonging to 3 families, 8 genus and 10 species were caught. The cyprinidae with 54.4% and salmonidae with 4.3% were the highest and the lowest percentages of native species, respectively. The results showed three major zones from four zones of the Huet's classification including trout, barbel, and bream. In addition, four distinct local zones were recognized along the river based on the presence of fish species. The trout zone with a length of less than 10 km and is of important conservation and management measures. This research addresses the longitudinal reaches of the Jajroud river that helps to conduct future ecological research in this river and also could  be an onset of using this method in other rivers in Iran to identify the longitudinal zones and the distribution pattern of fish fauna.

Ciliates are among the largest classes of protozoans. They can be found in almost every aquatic environment. Ciliates serve as an intermediate link in the energy transfer chain from picoplankton to zooplankton. They also serve as indicators of water eutrophication and pollution. Given the important roles that ciliates play in the ecology of aquatic ecosystems, their identification, morphological aspects, and taxonomic position are of great importance in order to conduct ecological studies. The present research aims to identify and study the plankton and periphyton ciliates of the Zayandeh Rud river and the reservoir. The identifications were done using the available keys and catalogs. As a result, 45 species from 30 genera and 19 families were identified in this study. There are nine families belonging to the suborder Gymnostomata, three families belonging to the suborder of Trichostomata, and seven families belonging to the suborder Hymenostomata. For the first time in this study, 45 new species of ciliates were reported in the study area and 25 new species in the country's aquatic ecosystems