Determination of maximum allowable concentration and LC50 96h of Sefidroud River sediments for Persian sturgeon (Acipenser persicus) fingerlings

The impact of Sefidroud River sediments on the fingerlings of Persian Sturgeon (Acipenser persicus) was studied in 2005. The tests were done in 20 liter aquariums each containing 10 Persian Sturgeons fingerlings weighing 3-5 grams each. We devised 6 treatments and a control with 3 repetitions in the four day investigation through which the lethal concentration (LC50 96h) of Sefidroud sediments were studied. During the test, physicochemical parameters of water such as pH, oxygen and temperature were measured as 8, 8.5mg/1 and 25±1°C respectively. The results showed that LC5096h and LC50 24h of sediments on Persian sturgeon were 15367.39mg/1 and 124882.04mg/1 respectively. We determined the maximum allow-able concentration (M.A.C) of sediments to be I 536.74mg/l

Effects of enriched daphnia with microscopic algae on some growth indices and survival rate of Persian sturgeon (Acipenser persicus) larvae

Microalgae as a source of valuable compounds such as fatty acids are isolated from the natural environments and their mass production with high nutritional value is one the necessities of many hatcheries. The present study aimed to determine the effects of enriched daphnia with microscopic algae on some growth indices and survival rate of Persian sturgeon (Acipenser persicus) larvae. Chlorella vulgaris and Scenedesmus dimorphus were purified and cultured. Then, Daphnia longispina was fed microalgae including Chlorella vulgaris and Scenedesmus dimorphus enriched with Docosahexaenoic acid (DHA). The microalgae density to enrich daphnia was estimated at 5× 107 cells mL-1. Three treatments with three replicates and a control group were considered in this study. A total of 30 Acipenser persicus larvae were allocated to each sixty liters tank. Experimental fish were fed daphnia enriched with Chlorella vulgaris (treatment 1), daphnia enriched with Scenedesmus dimorphus (treatment 2) and daphnia enriched with Chlorella vulgaris and Scenedesmus dimorphus (at the rates of 50%) (treatment 3). Persian sturgeon larvae in the control group were fed like VNIRO stage from daphnia caught in pond. Larvae were fed 30% of body weight per day for four times. During the experimental period, water temperature, dissolved oxygen concentration and pH ranged between 18-24°C, 5.8-7.2 mg l-1 and 5.6-8.2, respectively. The minimum (219 ± 98.4 mg) and maximum (315.16 ± 140.8 mg) mean (±SD) weights were observed in the control group and treatment 3, respectively. The results obtained from the body weight increase (BWI %) revealed that there were significant differences between treatment 3 and other treatments. Highest (4.6±1.13% day-1) and lowest (5.5±1.24% day-1) mean (±SD) specific growth rates (SGR) were recorded in fish fed the control group and treatment 3, respectively. Lowest (68%) and highest (85%) survival rates were recorded in the control group and treatment 3, respectively

Determination of LC_(50) 96h of dyazinon, hinosan and tilt for Acipenser nudiventris fingerlings

The toxic effects of agricultural pesticides Dyazinon, Hinosan and Tilt (Propiconazole) were studied on Acipenser nudiventris fingerlings (1-3g) in Spring 2005. We conducted our experiments in aquaria holding 20L water in static systems based on O.E.C.D method using five treatments, one control concentration and three replications. In each aquarium, ten individual Ship Sturgeon fingerlings were introduced, and water physical and chemical factors were controlled to be in the range pH=7-8, TH>400mg/l (CaCO _(3)) as for the water used for culture, and DO=80% and temperature was kept between 24 ±1°C. Our results for the LC _(50) value of Dyazinon, Hinosan and Tilt in 96 hours were 0.36, 0.28 and 3.9mg/l in the fish fingerlings. We also determined the maximum allowable concentration value of the toxins at 0.036, 0.028 and 0.39, respectively

The role of daphnia fed with purified and enriched phytoplankton with PUFA in enhancing growth and survival of Acipenser persicus larvae

In this study, Daphnia longispina were fed with two freshwater green algae species, Chlorella vulgaris and Scenedesmus dimorphus, enriched with Docosahexaenoic acid (DHA). Chlorella vulgaris and Scenedesmus dimorphus were isolated and cultured for mass production. Three treatments with three replicates and a control group were considered to conduct this study. In order to investigate feeding, a total of 30 Acipenser persicus larvae with the initial mean weight of 68±3.6 mg were distributed into 12 plastic tanks of 60 L. Experimental fish larvae were fed daphnia collected from earthen ponds (as control group), daphnia enriched with Scenedesmus dimorphus (treatment 1), daphnia enriched with Chlorella vulgaris (treatment 2) and daphnia enriched with Chlorella vulgaris and Scenedesmus dimorphus (at the rates of 50%) (treatment 3). The microalgae density to enrich daphnia is estimated at 5×107 cells mL^-1. Fish larvae were fed at an amount of 30% body weight per day for four times. During the experimental period, water temperature, dissolved oxygen concentration and pH ranged between 18-24°C, 5.8-7.2 mg l^-1 and 5.6-8.2, respectively. Monounsaturated fatty acids (MUFA) were the highest (32.3 %) in D. longispina enriched with Chlorella vulgaris and the highest concentration of polyunsaturated fatty acids (PUFA) (19.8%) was observed in D. longispina enriched with Scenedesmus dimorphus. The highest (21.6%) and lowest (13.2%) concentrations of PUFA in fish larvae were recorded in treatment 3 and the control group, respectively. The results obtained from the body weight increase (BWI %) revealed that there were significant differences (P≤0.05) between treatment 3 (daphnia enriched with chlorella and scenedesmus) and other treatments. The highest (5.5±1.24% day^-1) and the lowest (4.6±1.13% day^-1) mean specific growth rates (SGR) were recorded in fish fed treatment 3 and the control group, respectively. The lowest (68%) and the highest (85%) survival rates were obtained in the control group and treatment 3, respectively