International Journal of Aquatic Biology
Volume:9 Issue: 6, Dec 2021

In the present study, the effects of dietary supplementation of garlic extract on growth performance, skin mucus immunological parameters and antibacterial activity of Carassius auratus were examined. Fish were stocked in 100 L glass tanks (6 fish per tank) in triplicate and fed diets containing different garlic extracts (0 (control), 5, 10, and 15 ml/kg] for eight weeks. At the end of feeding period, the fish skin mucus was collected for evaluating the components of non-specific immune system (including lysozyme, complement, total immunoglobulin, dissolved protein, and alkaline phosphatase). Additionally, antimicrobial activity of the skin mucus against Aeromonas hydrophila, Yersinia ruckeri, Micrococcus luteus, Streptococcus faecium, and S. iniae was assessed. After the feeding trial, the fish fed diets containing garlic extract showed no significant difference in growth parameters. Significantly higher skin mucus lysozyme, complement, alkaline phosphatase activities, and total immunoglobulin and dissolved protein concentration were observed in the fish fed garlic extract-supplemented diets (P<0.0001). The antimicrobial activity of the skin mucus increased along with the increase in the dietary garlic extract levels (P<0.0001). Moreover, garlic extract exhibited the antimicrobial activity against pathogenic bacterial species. The highest level of dietary garlic extract (15 ml/kg) led to significantly higher inhibition zones against pathogenic bacterial species compared to the other garlic extract levels (P<0.0001). The optimal administration of garlic extract at 15 ml/kg enhance skin mucus immune parameters and antimicrobial activity in goldfish.

West African ladyfish, Elops lacerta is a pelagic fish present in the coastal waters of West Africa from Mauritania to Angola. This study is conducted to provide data on the growth and exploitation parameters of E. lacerta important for the management and conservation of this species in the Ivorian’s Exclusive Economic Zone (EEZ). These parameters were estimated by the indirect method using length frequency data collected in the Ivorian’s EEZ during January 2019 to December 2020. Monthly length frequency data were analyzed by FiSAT II software. A total of 865 specimens were examined. The growth parameters from von Bertalanffy growth function (VBGF) estimations were L∞ = 60.38 cm fork length, K = 0.39 year−1, and t0 = 0.46 year. The estimated potential longevity (tmax) was 7.69 years. The exploitation parameters showed that the total mortality rate (Z), natural mortality rate (M) at 28.35°C and fishing mortality rate (F) were 1.57 year−1, 0.80 year−1 and 0.77 year−1, respectively. The exploitation rate (E = F/Z) was 0.49. This value is lower than the optimal exploitation value (E50), thus expressing a case of under-exploitation of the species in the Ivorian’s EEZ. The size of first capture (Lc) below the size of first sexual maturity (FL50) and the optimal size of capture (Lopt) requires the implementation of an adequate mesh size management policy to allow fish to reproduce several times before being captured.

Several effective fungicides have recently been applied, but they can harm ecosystems and non-target organisms. The findings of this study should be helpful to evaluate the reproductive response of redbelly tilapia, Coptodon zillii, of both sexes upon exposure to 0.8 and 1.6 μg/L penconazole and 7.5 and 15 mg/L copper nanoparticle as fungicides for three months. The gonadosomatic index of males increased in the penconazole groups in parallel with testosterone. A significant increase was observed in estradiol and progesterone of penconazole and copper nanoparticle groups. In testicular homogenate, there was a significant decrease in superoxide radical in penconazole (I) and penconazole (II) groups and CAT of penconazole (I) and copper nanoparticle (I) groups, along with a significant increase in nitric oxide (NO) of Cu-NP (II) group. In ovarian homogenate, a significant increase in NO of penconazole (I) group and lipid peroxides of copper nanoparticle (I) group, along with decrease in CAT of penconazole (II) and copper nanoparticle (I) groups and SOD of penconazole (II) and copper nanoparticle (I) groups were found. The histopathological examination indicated gross deteriorations in the gonads of fish exposed to the fungicides except in the copper nanoparticle (II) group. These findings suggested the reproductive burden in C. zillii following exposure to the investigated fungicides by disrupting gonadal sex hormones and inducing redox imbalance and cytopathological abnormalities. It is recommended to reduce the flow of these materials to aquatic areas particularly the natural fisheries and artificial hatcheries.

This work was conducted to study the effect of salinity and pH on the absorption and accumulation of cadmium by the aquatic plant Lemna minor. Different concentrations of salinity (0, 1, 2 and 3 ppt) and pH (6.2, 7 and 8.4) were used. The results showed a decrease in the absorption of cadmium with increasing salinity, and the highest concentration of cadmium absorption at pH 6.2.

The study aimed to determine the concentrations of alkanes compounds using a gas chromatograph with high-precision separation techniques. Samples were collected from four stations in the Al-Gharraf River in southern Iraq during 2018-2019. A seasonal variation was observed in the concentrations of alkanes, which is the highest in the winter. The total alkanes concentrations were the lowest at 0.079 μg/g at station 1 in summer. The highest total concentration of alkanes was in station 3 in winter reaching 2.215 μg/g. There was a dominance of individual carbon compounds of C17, C19, and C21 indicating the source of hydrocarbon from phytoplankton, plant, and bacteria. The presence of carbon compounds higher than C25 reveals that organic matter is derived from land and aquatic plants. The results also indicate that the source of petroleum hydrocarbons in the sediments of the Al-Garraf River is a common biogenic and anthropogenic based CPI index and the pri/phy guide that was less than 1 in the second and third stations for all seasons, and greater than 1 in the first and fourth stations.

This study evaluated the oral administration of gamma-irradiated ethanolic extract of Iranian propolis on juvenile common carp. Fish were assigned into five groups and fed on the basal diet (control group) and an enriched diet containing 0.5 g kg-1 of GI-EEP supplements for 45 days. Growth performance, haematological indices, and immunological parameters were measured. The results showed that oral administration of GI-EEP (0, 10, and 30 kGy) significantly improved the growth performance. However, GI-EEP dietary supplements had no significant effects on the survival rate, haematological indices, catalase activity and total mucosal immunoglobulins of fish. A significant increase in lysozyme activities and total immunoglobulins was observed in fish fed on GI-EEP. The results suggested that feeding fish with 50 kGy of GI-EEP decreased certain growth performance indices and immunological parameters. The highest superoxide dismutase activity was observed in the fish fed on 30 kGy of GI-EEP, while the SOD activity significantly decreased in fish fed on 50 kGy of GI-EEP. The overall results of this study showed the use of GI-EEP at 10 and 30 kGy in the diet could improve growth indices and increase the efficiency of the innate immune and cellular antioxidant capacity. In contrast, the biological impact of EEP treated at 50 KGy gamma rays may be significantly reduced due to changes in its quality.

Fingerlings of Catla catla were exposed to 1, 5, and 25 mg/L of zinc oxide nanoparticles (ZnO NPs) for 15 days, and specific hematological and biochemical parameters were evaluated to assess the toxicity. During the exposure period, red blood cell (RBC) count was found to decrease (except at the end of the 5th day in 1 mg/L) whereas white blood cell (WBC) count was found to increase in ZnO NPs treated fishes. A significantly higher hematocrit (Hct) level was recorded in fish exposed to 1 mg/L when compared with control and a higher concentration of ZnO NPs (5 and 25 mg/L). Erythrocyte indices such as mean cellular volume (MCV) and mean cellular hemoglobin (MCH) values (except at the end of 5 and 10th day at 1 and 10 mg/L exposed groups) were significantly increased. Mean cellular hemoglobin concentration (MCHC) level was found to be increased at 1 and 25 mg/L treated groups compared to 10 mg/L. Compared to the control group, plasma glucose level was increased significantly in fish exposed to 5 and 25 mg/L concentrations of ZnO NPs, while the plasma glucose level was decreased at the end of the 15th day in all the concentrations. Plasma protein level was increased at the end of the 5th day while the level of plasma protein was decreased on the 10 and 15th day. A significant increase in glutamate oxaloacetate transaminase (GOT) (except at the end of 10th day) and glutamate pyruvate transaminase (GPT) activity in gill and liver (except at the end of 10 and 15th day in gill) were noted in all the concentrations tested when compared to control groups. The results of the present study indicate that ZnO NPs at 1, 5, and 25 mg/L can alter the hematological and biochemical parameters of fish and the toxicity data may provide the ecotoxicological impact of ZnO NPs on the aquatic environment.

Planorbarius corneus (Linnaeus, 1758) is the most widespread and numerous gastropods in Central-European waters, which range covers from the Atlantic to the Ural and outside the latter to the Ob river basin. Before the beginning of 21 century, malacologists had no doubts about its species status. This situation changed when genetic labeling showed that P. corneus is not a species, but a superspecies complex, Planorbarius (superspecies) corneus s. lato, according to the centromere indices of the 12th pair chromosome. This complex consists of two vicarious genetic allospecies, western and eastern one, which ranges are separated by a narrow (up to 100 km) zone of the introgressive hybridization lying just in Ukraine. Ecotoxicological features of P. corneus s. lato allospecies under the influence of any pollutants have not been studied yet. Our research focused on how different concentrations (0,001–1000 mg L-1) of some heavy metal ions (Cu2+, Zn2+, Ni2+, Mn2+) in the water environment affected the main ecotoxicological parameters of each vicarious allospecies, and on the limits of toxic effects for studied pollutants. We found the duration of the latency period, time-to-death, and mean time-to-death, as well as the coefficients of persistence and adaptation for each allospecies. According to our results, eastern allospecies are more sensitive to the heavy metals in the aquatic environment than western one. That creates a significant threat to the eastern allospecies populations, because the concentrations of these pollutants in the Ukrainian waters remain rather high, despite some positive downward trends.