Assessment of microplastic contamination in some commercial fishes of the southern Caspian Sea and its potential risks.

This study examined the occurrence of microplastics (MPs) in the gastrointestinal tract (GIT) of 384 fishes classified into four species from 11 sites in 2022 from the southern part of the Caspian Sea. GITs of fishes were collected and digested in H2O2 and KOH at 45 °C for 72 h. After filtration, extracted MPs were observed under a stereomicroscope, and selected MP particles were identified using FTIR. Presence of MPs was 68.98% in the GIT of the investigated fish. The mean abundance of MPs was 5.9 ± 0.9 MPs/GIT in Rutilus kutum, 9.2 ± 1.2 MPs/GIT in Chelon auratus, 3.6 ± 0.7 MPs/GIT in Alosa braschnikowi, and 2.7 ± 0.5 MPs/GIT in Vimba vimba. The predominant form of MPs was fiber (58.21%), followed by fragment (34.77%). Black (34.4%), white (19.07%), and blue (14.58%) were the most frequently detected colors of MPs. Overall, 6 MP polymers were identified, dominantly polypropylene (42.86%), polystyrene (17.86%), and cellophane (14.28%). The western part of the Caspian Sea (mostly tourist spots and urban areas) showed more MP pollution in fish compared to the eastern part. Polymer hazard index (PHI) revealed alarming microplastic contamination in the southern Caspian Sea. The PHI value of the present study showed that PES (PHI = 8403.78) and PS (PHI = 535.80) were "Extreme danger" and "Danger" risk categories, respectively.

Modulation of toxicity effects of CuSO4 by sulfated polysaccharides extracted from brown algae (Sargassum tenerrimum) in Danio rerio as a model.

Copper is widely used in agriculture and aquaculture due to its high disinfection properties and relatively low cost. However, the increase in copper concentration due to evaporation can lead to water reservoir pollution, which can harm the health of consumers. The present study aimed to determine the role of sulfated polysaccharides (SPs) extracted from Sargassum tenerimum algae in reducing lesions caused by the heavy metal copper. Zebrafish (Danio rerio) were used as a human model in five treatments. The negative and positive control groups were fed a diet containing zero percent of SPs, while the experimental groups were fed 0.5%, 1%, and 1.5% of SPs in three treatments for 56 days, finally CuSO4 was exposed only to the positive control group and the groups fed with SPs. Results showed a significant decrease in the activity level of ALT enzymes (39-16 U/mL), AST (67-46 U/mL), and ALP (485-237 U/mL), confirming the results obtained from histopathological studies in CuSO4 exposed groups. The addition of SPs to the diet resulted in a significant reduction (sig < 0.05) of mortalities due to the decrease of tissue damage. Additionally, due to the anti-inflammatory properties and the protective effect of SPs, a significant decrease (sig < 0.05) was observed in the relative expression of Il-1ß and Tnf-α genes.

Different land uses influenced on characteristics and distribution of microplastics in Qarasu Basin Rivers, Gorgan Bay, Caspian Sea.

Concerns about the negative effects of microplastics (MPs) on human health have led to increasing attention to the occurrence of MPs in the aquatic environment. Recent studies have focus on the spatio-temporal distribution of MPs in rivers for residential and agricultural areas. Qarasu River Basin, watershed to Gorgan Bay, is the site of many permanent rivers and the levels of MP pollution in those rivers are unknown. This research was conducted in three different types of land use: forest, residential, and agricultural along 8 different rivers. A total of 9 fish species were identified and the presence of MPs in 87% of fish was confirmed. The prevalence of MP among species was Liza sp. > Carassius gibelio > Gambusia holbrooki > Rutilus rutilus > Neogobius melanostomus > Cyprinus carpio = Vimba vimba > Rutilus frisii > Barbus sp. The highest frequency of MPs was observed in Qarasu River (1880 ± 251 n/kg) and Mohammadabad River (184 ± 1340 n/kg) in agricultural land use, and the lowest frequency was related to Baghu and Ziarat Rivers with 660 ± 77 and 600 ± 91 n/kg found in forest land use respectively. The highest type, color, and size of MP sediments were fragment, black, and 1-2 mm, respectively. The highest type, color, and size of MP in fishes were fiber, black, and 0.5-0.1 mm respectively. Overall according to the source tracing result, agricultural land use was the main source of MP pollution of Gorgan Bay. The Bay is strongly affected by the incoming rivers, the Qarasu River Basin as the most important river supplying water.

Dietary Beet Molasses Improved the Immune System of Common Carp (Cyprinus carpio) After Exposure to Titanium Oxide Nanoparticles, TiO2-NPs.

This study was carried out to evaluate dietary effect of beet molasses on immunity indices of common carp treated with titanium oxide nanoparticles TiO2-NPs. 250 fish were distributed in four treatments containing 0, 0.5%, 1% and 2% molasses and fed for 42 days, then fish were exposed to TiO2-NPs during a 14-day. At the end of experiment, hematological, biochemichal and mucusal immunity indices were evaluated. The aboved indices showed a significant difference compare to the control group (p < 0.05). Blood monocyte and lymphocyte in the TiO2-NPs with molasses group was reduced, that means molasses in combination with TiO2-NPs could alleviate the effect of TiO2-NPs. In treatments of TiO2-NPs and molasses combination, molasses was able to reduce the additive effect of monocyte, mean corpuscular hemoglobin concentration, alkaline phosphatase, alanine aminotransferase and aspartate aminotransferase. Molasses in combination with TiO2-NPs was able to improve the negative effect of TiO2-NPs, so 2% molasses in combination with TiO2-NPs, could neutralized undesirable effect of TiO2-NPs on common carp.

Microplastics distribution, abundance and composition in sediment, fishes and benthic organisms of the Gorgan Bay, Caspian sea.

Microplastic is releaseing to the aquatic environment worldwide, so they considered as a global issue and appeare to be widespread in all level of aquatic ecosystems and reveal serious threats to biota. Since they are often ingested by living organisms, the major concern is their transferring from lower trophic level to higher trophic level through the food chain. Due to the importance of Gorgan Bay as one of the ecologically important areas of the Caspian Sea and the need for fundamental information on the pollution status of this region, a study conducted for evaluation of microplastic pollution in sediments, fish and benthose, from 3 areas (north, central, south) through sampling from 21 stations. The range of microplastics (MPs) abundance in sediments was 80 ± 25 to 740 ± 105 n/kg. Fibers, Black MPs, and size of 1-2 mm (42.4%) were prevalence observed in sediment and living organisms. According to the FTIR results, among studied organisms, the most microplastic levels were found in the soft tissues of fish Neogobius melanostomus (39 MP/g) and mussel Cerastoderma lamarcki (19.8 MP/g) dry weight. The results of this study present the comprehensive information on MPs distribution and charecteristics in sediments, fish and mussel of Gorgan Bay which could help to run better management over this sensitive ecosystem and would be a start point for further research on MPs effect on organisms of the Caspian sea.

Effects of Probiotic Bacteria Bacillus on Growth Performance, Digestive Enzyme Activity, and Hematological Parameters of Asian Sea Bass, Lates calcarifer (Bloch).

This study was conducted to evaluate different doses of two species of Bacillus (Bacillus licheniformis and Bacillus subtilis), on growth parameters, chemical composition of fish, activity of liver, and digestive enzymes of Asian sea bass. During 8 weeks, juvenile Asian sea bass received diets supplemented with 1 × 103, 1 × 106, and 1 × 109 CFU g-1 probiotic in addition to a control diet without added microorganisms. At the end of the trial, growth indices (total weight, total length, specific growth rate, total weight gain, food conversion ratio, and condition factor), body composition (crude protein, crude lipid, ash, and dry matter), digestive enzymes (protease, lipase, and amylase), liver enzymes [aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP)], immunologic indicators (lysozyme), and hematological parameters [hematocrit (Hct), hemoglobin (Hb), red blood cells (RBCs), white blood cells (WBCs)] were assessed. Asian sea bass receiving diets supplemented with probiotic Bacillus (Bacillus licheniformis and Bacillus subtilis) showed significantly better growth than those fed the basal diet (control). Regarding body composition, total protein levels and dry matter were higher and lipid levels were lower in fish fed the diet containing 1 × 106 CFU g-1 probiotic compared with the control group (P < 0.05). Digestive enzymes (protease, lipase, and amylase) and hematological parameters (RBC, WBC, and Hb) were all highest in fish fed diet supplemented with 1 × 106 CFU g-1 probiotic Bacillus. Also, liver enzymes (AST, ALT, ALP) were lower in fish fed diet supplemented with 1 × 106 CFU g-1 probiotic Bacillus. Being that supplementation of 1 × 106 CFU g-1 of Bacillus in the diet is the dose which delivers the best results.