International Journal of Aquatic Biology
Volume:12 Issue: 4, Aug 2024

The present study assessed the effects of dietary supplementation with Cirsium arvenseessential oil (CAEO) on growth and antioxidant responses in rainbow trout, Oncorhynchus mykiss. Four diets were prepared containing 0 (CTR), 2 (CAEO2), 4 (CAEO4), and 6 (CAEO6) mL/kg CAEO and offered to fish (31.31±0.15 g) in triplicate for 60 days. Dietary CAEO significantly increased growth, feed efficiency, intestinal chymotrypsin, trypsin, serum superoxide dismutase (SOD), catalase (CAT), andglutathione peroxidase (GPx). Dietary CAEO significantly decreased serum malondialdehyde. The highest growth rate, gut chymotrypsin, and serum GPx were observed in CAEO6, whereas the highest feed efficiency, intestinal trypsin, serum SOD, and CAT, and lowest serum MDA were observed in CAEO4 and CAEO6. In conclusion, CAEO can be used as a feed additive for the aquaculture of rainbow trout, as it improves theproduction and antioxidant of the fish at a concentration of 6 mL/kg.

This study examined the occurrence, characterization, and hazard risk of microplastics (MPs) in the edible tissues of commercial fish from public wet markets in Cebu Province, Philippines. Fish samples from eleven species were collected from eight municipalities (Argao, Bogo City, Carcar City, Daanbantayan, Liloan, Naga City, Oslob, and Toledo City) and analyzed for microplastics using microscopy and ATR-FTIR. Three hundred eighty-nine MP particles were identified, with benthic fish (N = 197) showing a slightly higher count than pelagic fish (N = 192). Argao had the highest MP count (N = 60), while Daanbantayan had the lowest. Euthynnus affinishad the highest MP concentration (19%, N = 74), followed by Scarus psittacusand Cypselurus opisthopus(16%, N = 64 each). Of the samples, 30% were confirmed as microplastics, revealing 15 distinct polymer types, including polyvinyl alcohol (PVA) (20%), polyacetylene (PA) (17%), and polyvinyl chloride (PVC) (7%). The polymer hazard index (PHI) indicated that polyethylene (PE) and polyethylene terephthalate (PET) posed a "High" risk, while acrylonitrile-butadiene-styrene (ABS), PVC, and polyurethane (PU) were classified under "Extreme Danger". These findings suggest that local agricultural practices, laundry activities, and waste disposal contribute to MP contamination in fish tissues, warranting further investigation into the health implications of MP consumption.

Recirculating aquaculture systems (RAS) present a problem involving the accumulation of NO3-and PO43-atthe end of the culture. The study aimed to identify native aquatic plants ofPistia stratiotes, Lemna minor, Salvinia molesta, and Eichhornia crassipeswith wastewater treatment capabilities in RAS. The catfish, Clarias macrocephalus, weighing 60 g each, were stocked at a density of 65 fish/100L and fed a diet of floating pellets containing 41% crude protein. Pistia stratiotes was the most effective macrophyte for treating wastewater from the catfish culture system during the first 10 days of the experiment. Following treatment with P. stratiotes, the concentrations of CO₂, COD, TAN, N-NO₃⁻, P-PO₄³⁻, and TP in the wastewater decreased by 65.83, 34.28, 40.70, 46.70, 24.56, and 9.16%, respectively, while dissolved oxygen increased by 37.68% compared to the initial concentrations. Further research isrequired to thoroughly comprehend the efficacy and long-term effects of the P. stratiotesin RAS.

This study investigates the preparation and characterization of nano-antioxidant formulations using ionic cross-linking between silymarin and chitosan polymer to produce Silymarin-Chitosan Nanoparticles (S-CsNPs). Silymarin, Silybum marianum, is renowned for its hepatoprotective properties, attributed to its antioxidant activity. However, its clinical efficacy is limited by poor oral bioavailability, primarily due to low water solubility and rapid systemic clearance. To address these challenges, this research uses nanotechnology to enhance silymarin's solubility, stability, and bioavailability. Through ionic gelation methods, silymarin is encapsulated within chitosan, a biocompatible and biodegradable polymer, to protect it from physicochemical degradation and enhance therapeutic efficacy. Initial findings highlight the potential of this nanoparticulate system in improving dissolution.Based on the results, silymarin was effectively loaded onto chitosan. SEM analysis showed that the size of the nano-silymarin particles ranged from 25.81 to 43.03 nm. Additionally, XRD analysis confirmed the crystalline nature of the S-CsNPs. The study also observed a relatively smooth surface and homogeneous distribution of the S-CsNPs particles.

Given the textile sector's intense economic activity, its effluents are known to contribute to water quality degradation, with ecological and ecotoxicological implications. This study aimed to evaluate the influence of pure textile dyes (tartrazine yellow and indigo blue) on the growth of the cyanobacterium species Microcystis aeruginosathrough direct and indirect methods. Furthermore, it aimed to verify whether this species has bioremediation potential in effluents contaminated with dyes through ecotoxicological evaluation and color reduction. Therefore, we added an inoculum of 3x103cells/mL of M. aeruginosato a concentration of 500 mg/L of each pure dye in solutions with WC medium. They remained in direct and indirect light for seven days, and the number of cells was evaluated over 168 hours. Then, we collected two types of effluents representative of the dyes studied (jeans factory blue dye and carpet factory yellow dye), which remained raw and diluted by 50%. We added an inoculum of 8.64x103± 93 cells/mL of this cyanobacterium to each effluent. Moreover, we added a control without inoculum for each condition. Aeration remained constant for 25 days. We conducted ecotoxicological evaluations of the effluents (before and after 25 days of bioremediation) through seven-day assays with the larvae of Danio rerio, verifying survival and growth parameters. The results showed that the cyanobacterium grew significantly in direct contact with the tartrazine yellow dye (1.49x105± 1910 cells/mL). However, growth wasreduced with both dyes in indirect contact, and there was total inhibition with indigo blue in direct contact, significantly differing from the control. After 25 days, the number of cells in the effluents diluted by 50% decreased compared to the inoculated amount. Considering the color reduction in the carpet factory effluent (100%), the presence of cells enabled a 43% reduction, and in the only aerated condition, 34.6% decolorization. Thus, considering the greater color degradation in the presence of cyanobacteria in this effluent, we believe that cell growth and active metabolism occurred before the 25 days tested. The color removal percentages in the presence of cells did not reduce toxicity. Therefore, we concluded that M.aeruginosahas the potential to grow in high concentrations of tartrazine yellow (500 mg/L).

Antibiotics belong to a large group of pharmaceutical substances that tend to kill or prevent the growth of bacteria like rifampicin and other antibiotics. The overuse of rifampicin has resulted in the accumulation in the natural environmentand has potential health hazard that involves carcinogenicity, mutagenicity, reproductive toxicity, and neurotoxicity. This study focuses on the toxic effects of rifampicin on zebrafish embryosandfollows OECD 236 guidelines. The embryos are treated with 1.25, 2.5, 5, and 10 mg/L of rifampicinfor a range of 4-96 hours post-fertilization. Exposed zebrafish embryos showed a variety of deformities in somites, spines, tails, hearts, and yolk sacs. Heart rate was decreasing with increasing centration of rifampicin. For adults, we exposed 5, 10, and 20 mg/L of rifampicin. The hepatotoxicity was assessed by expression of SOD, GH1, and TNF-α gene and observed a spike inthe expressed at a low dose (5 mg/L) by 2.13-fold, 15.6-fold, and 3.53-fold, respectively. MDA levels were 0.32 and 0.39 nM at 10 and 20 mg/L ofrifampicin, respectively. Therefore, zebrafish provide newinsights into the toxicological effects of pharmaceuticals, and we found teratogenicity and rifampicin-induced hepatotoxicity in adult zebrafish.

This study evaluatedthe Tigris River's water quality in Baghdad City for four different purposes, including drinking water supply, aquatic life, and agricultural requirements using Canadian WQI. The evaluation is based on data collected over 2021 and 2022.The parameters of water temperature, turbidity, total dissolved solids, pH, DO, nitrate, nitrite, ammonia, phosphate, chloride, fluoride, magnesium, calcium, sulfate, sodium, magnesium hazard (MH), and sodium adsorption ratio (SAR) were measured for index CCME calculation. The results indicated that water temperature and turbidity are the variables that crossed standard guidelines for aquatic life protection, ranked within fair quality. In contrast, water temperature, turbidity, and TDS are the variables that exceeded the allowable levels for overall water quality, mainly ranked within a good class. For drinking water purposes, turbidity and Ca are among the parameters that fall outside the acceptable limits, rated between marginal and fair class.

This study is aimed to provide detailed information on the diet of Rhizoprionodonacutusin the Gulf of Suez. The findings suggest the specialized feeding behavior of this species in the Gulf of Suez. A total of 240 Stomachs of R. acutuswere examined. The number of stomachs that contained prey items was 146 (60.83%), while 94 stomachs were empty (39.16%). Identifiable prey items belonging to 24 species of marine organisms correspond to 13 families of teleost fishes, three families of cephalopods, two families of crustaceans, one of eels, and oneof sea urchins. Prey items of little importanceincluded the teleost fishes Lutjanus bohar(0.003%(and the sea urchin Clypeaster humilis, (0.004%); each was only found in one stomach. Unidentified teleosts comprised the bulk of the observed prey items in terms of frequency of occurrence (63.7%),number (66.67%), weight (53.94%), and relative importance (96.54%). The identified prey items contained pelagic, demersal, reef-associated, and benthic organisms. When grouping food items into their large categories and comparing them in terms of %IRI, teleost fishes were the preferable prey item, with 96.54% unidentified and 1.49% identified, followed by Cephalopods (1.73%), eels (0.16%) and finally, Crustacean (0.09%). The trophic level of R. acutusin the Gulf of Suez was estimated to be 4.2, which categorizes it as a tertiary consumer.

PAHs are toxic pollutants that endanger human health and the environment. This study aimed to assess the PAH levels in sediment and two tilapia species of Oreochromis niloticusand Coptodon zilliiinthe Shatt Al-Arab Riveralong theBasrah City, southern Iraq, from May to October 2021. In addition, the risk to human health from fish was calculated using dietary daily intake and the carcinogenic potencies of PAH concentrations. Sixteen PAH congeners were found in sediment and fish samples. The total PAH concentrations in sediment and fish samples ranged from 37.46 to 76.33 μg/g dry weight and 23.55 to 55.81μg/g wet weight. The total concentration pattern of PAHs wasas follows: Sediment > O. niloticus> C. zillii. PAH levels in the fish's dietary intake were 0.00866 mg/kg body weight/day for 8 PAHs and 0.01288 mg/kg body weight/day for 16 PAHs, respectively. The TEQ (0.0025888mg/kg body weight/day) exceeded the SV (0.677 ng/g wet weight) of the USEPA.

The study investigated the influence of continuous illumination at increasing light intensities on feeding, growth, and survival of early-stage snubnose pompano,Trachinotus blochii,larvae from 1 to 10 days post-hatching (DPH). Fish larvae were exposed to 5 treatments with 3 replicates [T1-natural indoor 12 hours light (hL): 12 hours dark (hD), T2-300-500 lux (lx), T3-300-1000 lx, T4-300-2000 lx, and T5-300-3000 lx]. Newly hatched larvae were stocked at 15 ind. /L density and fed with enriched rotifers (Brachionus plicatilis; 50-250 μm) at 30 ind. /ml starting from 2 DPH. The number of rotifers in the digestive organ, feeding incidence, and total length of larvae were examined at 3-hour intervals from 0400 to 2200 hours (H) on 3 DPH, at 6-hour intervals from 4 to 5 DPH, and once on 8 DPH at 1000 H. The results justified that snubnose pompano was a visual feeder and exhibited diel rhythm within 24 hours of light, while larvae at natural photoperiod usually underwent diurnal rhythms. However, changing light intensity conditions from low to high levels altered the feeding behavior of the fish larvae. Better and consistent feeding and survival of larvae were obtained at moderate continuous illumination at increasing light intensities (300-500 lx). While higher light treatments (300-1000, 300-2000) can yield more remarkable fish growth, they adversely affect larval survival after 5 DPH. In conclusion, moderate continuous illumination (300–500 lx) promotes consistent feeding, resulting in a positive growth response and improved survival in early-stage snub nosepompano.

This study aimed to examine the growth performance of common carp, Cyprinus carpio, fry in different stocking densities in the environmental conditions of central Iraq. The experiment was performed for 60 days at the central fish hatchery in the Suwayra district, the Kut Province. The study examined four groups: three with different stocking densities (1 million (T1), 1.5 million (T2), and 2 million (T3) fry per hectare) and a control group (T0) without supplementary feeding. The fry were reared in earthen ponds, with water quality parameters constantly monitored and maintained within optimal conditions. The results revealed that stocking density significantly impacted growth performance and survival rates. T2 exhibited the highest survival rate (84.91%) and the greatest final average weight (8.23 g). Furthermore, T2 displayed the highestspecific growth rate (SGR) and daily weight gain (DWG), suggesting that this stocking density is optimal for the prevailing conditions in central Iraq. The economic analysis revealed that T2 had the highest profitability, with a benefit-cost ratio (BCR) of 1.2, followed by T1 (BCR = 1.18) and T3 (BCR = 1.00). Feed expenses accounted for the majority of total costs, emphasizing the importance of efficient feed management. The findings underscore the importance of maintaining optimal stocking densities and implementing effective feeding strategies to enhance growth performance and economic sustainability in common carp farming in Iraq.