International Journal of Aquatic Biology
Volume:7 Issue: 5, Oct 2019

In the current study, the retinoic acid isomers such as 9cis retinoic acid and alltrans retinoic acid were detected in the mature ovaries of mud crabs, Scylla serrata using HPLC analysis. Given the detection of retinoids in the ovaries, an attempt has been made to elucidate the possible role of retinoic acid in the regulation of reproduction in mud crabs. Injection of 9cis retinoic acid induced ovarian maturation in intact mud crabs as evidenced by a significance elevation in the ovarian index (226.76%; P <0.001), and oocyte diameter (150.61%; P <0.001) accompanied by accumulation of yolk globules in the oocytes as compared to the untreated crabs. Further, a significant increase (258.63%; P <0.0001) in the circulatory ecdysteroid levels were also observed in 9cis retinoic acid injected mud crabs over vehicle injected crabs. From the results, it can be postulated that retinoic acid-induced stimulation of ovarian maturation at least in part mediates ecdysteroids in the mud crabs.

The diversity of macroalgae and evaluation of the Algerian coastal waters using EEI-c index were studied. Macroalgae were sampled at seven stations in summer 2019. Coverage data for the macroalgae at each site were analysed at species level. Eleven species have been identified and the results showed the prevalence of Cystoseira compressa and Ulva sp .. The least abundant species were Cladophora sp. and Corallina elongata . Classification of sites based on the cluster analysis shewed an agreement with the water degradation information. Based on the results, the EEI-c values were quite homogeneous over all the studied sites, and generally correspond to undisturbed states except for one site.

In this study, 32 male and female Caspian kutum were anesthetized with clove extract (50 mg/L), lidocaine (150 mg/L), and sodium bicarbonate (300 mg/L). Blood parameters and serum cortisol levels were investigated in the control (no anesthetic) and the treated groups containing both males and females in 10 min and 24 h after anesthesia. Based on the result, difference in the red blood cells in the control group and treated groups males was not significant. In females, however, the red blood cells in all treated groups was different except lidocaine treatment after both sampling times ( P >0.05). The white blood cells of males and females in control group was significantly different in the sodium bicarbonate group in 10 min and 24 hours after anesthesia ( P <0.05). The hemoglobin and hematocrit did not change in male and female fish in lidocaine treatment after both times. Cortisol changed in male and female in the sodium bicarbonate group after both times. The WBCs in females was significantly higher in clove extract and lidocaine treatments, whereas RBCs, Hb, Hct, and cortisol were significantly higher in males ( P <0.05). Therefore, due to irreversible stressful effects of the sodium bicarbonate, it is not a suitable anesthetic for the studied fish. Although the stressful effects of lidocaine were lower than clove extract, especially in females, the clove extract has no irreversible effects and the stress-induced effects had been moderated 24 h after anesthesia. Hence, lidocaine and then clove extract is recommended as suitable anesthetics, especially for female Caspian kutum.

This study investigated microbial load and diversity of gastro-intestinal tract of the cultured Nile tilapia ( Oreochromis niloticus ) and hybrid catfish ( Clarias gariepinus ♀ x Heterobranchus bidorsalis ♂) in Ilorin metropolis, Nigeria. A set of apparently healthy Nile Tilapia and hybrid catfish were obtained from a fish farm in Ilorin metropolis. After dissecting the fish sample aseptically, the entire alimentary canals of the specimens were divided into foregut, midgut and hindgut. Then bacterial isolates were characterised, following standard operating procedures for gram reaction, morphology, motility, catalase and oxidase reactions, citrate utilization, coagulase production, starch hydrolysis, sugar fermentation, and eventual identification of the resultant colonies. The moulds were examined based on their micro-morphology as well as the colour and micro-morphology of their sporulating structures and conidia. The results of the study revealed that microbes were present in the entire gastro-intestinal tract of cultured hybrid catfish and Nile tilapia with highest microbial load found in the hindgut of the two fish species under study. Also, larger number of bacteria diversity indices were found in the hindgut of cultured Nile tilapia, while the hindgut of cultured clariid catfish had higher fungi diversity indices.

Heavy metals are generally discharged from untreated wastewater in the aquatic ecosystem. This study was aimed to investigating the effective parameters in the sorption of nickel metal by a native halophile bacterium isolated from sediments of the Miankaleh Wetland in the north of Iran. Halobacillus sp. KN57 as the most resistant Gram-positive strain was selected and identified by phenotypic and phylogenetic properties (16S rRNA). The optimum contact time, pH, temperature, salinity, and initial biosorbent concentration of nickel for this strain were 100 min, 7, 30°C, 10%, 1 g.L-1, and 150 mg.L-1, respectively. The nickel biosorption was 111.11 mg/g by the selected strain under the laboratory conditions, followed Langmuir isotherm with a correlation coefficient of more than 0.98 and the maximum single layer sorption. In addition, the kinetics of nickel biosorption of this strain correspond to a pseudo second order kinetic model with a correlation coefficient of more than 0.99. Scanning electron microscopy was applied to confirm the biosorption of Ni2+ by Halobacillus sp. KN57. Finally, the FT-IR spectrum identified that the amide, carbonyl, and amine functional groups were participated in binding to nickel ions. The results showed that the native bacterial strain ( Halobacillus sp. KN57) isolated from Miankaleh Wetland, is potentially a promising biosorbent for sorption of nickel metal.

The skin of a fish acts as the primary protective agent against biological, physical, and chemical stress. However, the effects of such stressors on fish mucosal immune responses have been hardly investigated. Fasting or feed deprivation commonly is occurred in aquaculture due to season, production policies, or disease. This research was aimed to investigate the impacts of 20-day starvation on skin mucosal immune responses of rainbow trout. The results revealed that the enzymatic activities of lysozyme (LZM) and alkaline phosphatase (ALP), as well as the total immunoglobulins (Ig) level and bactericidal activities were significantly reduced in the skin mucus of fasted fish. No significant changes were observed in the esterase and protease activities. Bactericidal activity in the mucus of starved fish was significantly lower than control group after 20 days. Therefore, it could be strongly suggested that this species should not remain under starvation stress as this kind of stress impairs mucosal immune barriers which, in turn, could make the fish more susceptible to infections or harmful agents.

The present work aimed to explore the effects of nutritional ginger on rainbow trout. The fish were fed various concentrations of ginger extract i.e. 1, 3, 6, and 10 g/kg; the control was fed no ginger. Having fed for 56 days, the fish were exposed to Yers inia ruckeri and any case of death was documented for two weeks. The diet with the extract of ginger could check the experimental infection in rainbow trout. The highest survival rate, i.e. 91.4%, was attained in the group nourished with ginger at 10 g/kg while the survival rate for the control was 41.6%. Ginger diet of 6 and 10 g/kg affected the biochemical parameters and the immune response. Total serum protein and total serum immunoglobulin, together with lysozyme, phagocytic, bactericidal and antioxidant enzymes activities, significantly improved in some groups, other than the control, in a dose-reliant mode (P<0.05). No variations were detected in the levels of alanine aminotransferase, lactate dehydrogenase, and aspartate aminotransferase activities in the ginger-fed groups, indicating no liver toxicity. The findings of the current research revealed that some doses of nutritional ginger (6 and 10 g/kg) could reinforce the non-specific immunity and diminish the vulnerability of rainbow trout to Y. ruckeri .

This study aimed to examine two concentrations of Rosa damascene extract on toxic effect of Zn on the liver of common carp. For this purpose, four treatments with three replicates were designed as following: treatment one as control, treatment 2 exposed to 3 mg/l ZnSO4, and treatments 3 and 4 supplemented with 2.5 and 5 g of R. damascene extract along with exposure to 3 mg/L ZnSO4. After 45 days, the bioaccumulation of Zn and histopathological alternation in the liver, as well as aspartate aminotransferase (AST), alanine transaminase (ALT), triglyceride, cholesterol and albumin were measured. The results showed the highest concentration of Zn in treatment, and its decreasing trend in treatments 3 and 4. The histopathological examinations showed the most alternations in treatment 2, but lower changes in treatment 3 and 4 due to application of R. damascene extract. In addition, those measured biochemical parameters had increased in treatment 2 following exposure to ZnSO4, whereas they had decrease in treatments 3 and 4. These results revealed positive effect of R. damascene extract to decrease toxicity of Zn on the liver of common carp.