Journal of Aquatic Ecology

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Length-weight relationship (LW), condition factor and frequency length of 4190 individuals of the oriental river prawn (Macrobrachium nipponense) collected from western part of the Anzali Lagoon were studied during 2015. Sampling was conducted by using cylindrical pot (CP), opera house traps (OHT) and Hokkaido pot (HP) having oval base. Traps containing baits were checked every 24 hours and the samples were transferred to the laboratory. The results indicated that correlation of LW was 0.93 and 0.89 in males and females, respectively. The coefficient “b” was 3.16 in males and 2.86 in females. The analysis of the coefficient “b” in LW relationship using Paoli test indicates that growth model in both sexes are allometric. The results of frequency length showed significant differences between CP and OHP traps. However, no significant differences were observed among HP, CP and OHP traps. In addition, condition factor showed significant differences among all the traps. The results suggested that, OHT trap can trap prawn with higher length frequency and condition factor.

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This study was carried out to determine the level of heavy metals contamination in the sediments and stone snail Tylothais savignyi from Kharg Island and to determine the potential of the snail to serve as a biomonitoring agent. A sampling of surface sediments and snail was carried out from five different stations in September 2013 and March 2014. Samples were transferred to the laboratory and oven-dried. The samples then were acid digested and their heavy metals content was measured using GBC flame atomic absorption spectrophotometer (model Savantaa Σ, Australia). The results showed that the concentrations of copper, zinc, nickel, and lead in the sediment of Kharg Island was in the range of 26.4- 38.2, 63.9-75, 35.7-52.6, and 27.2-35.9 μg/g of dry weight, respectively, while cadmium concentrations were below the detection limit of the apparatus. The concentrations of copper, zinc, nickel, lead and cadmium in the soft tissue of the T. savignyi were 362.3-590, 127.4-183, 6.9-11.2, 24.1-43.9, and 8.4-18.2 μg/g of dry weight, respectively. Similarly, the concentrations of copper, zinc, nickel, and lead in snails shells were 31.5-49.4, 18.2-24.5, 7.1-8, and 27.4-33.9 μg/g, respectively. Similar to the sediments, cadmium concentrations were below the detection limit of AAs. The comparison of the results with previous studies and the available standards showed that heavy metal concentrations in the sediments were lower than the standard levels. Meanwhile, the concentrations of copper, nickel, lead, and cadmium in the soft tissue of the snail were appeared higher than standard levels. These results indicate that the snail has a strong capacity to accumulate heavy metals from its surrounding environment. Therefore, the snail has a significant ability to accumulate metals in its soft tissue.

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The purpose of this study was to evaluate the antioxidant power of knife shells, Solen dactylus using DPPH, reducing power, and TAC methods. Twenty shells were sampled at Ghouban Estuary in autumn and spring. 2 ml of pure methanol was added per 1 g of sample, and centrifuged at 11,000 rpm for 30 minutes. Then the supernatant was removed and transferred to the rotary machine for 5 minutes. In this method, 100 μl of the sample extract (0.5 g/l concentration) was added to 2 ml of DPPH (0.6 mm DPPH in 95% methanol) in a test tube and distilled into 3 ml distilled water. The reaction solution was then shaken vigorously and allowed to stand at room temperature in the dark for 30 minutes. The optical absorbance of the solution was measured in a wavelength of 517 nm using a spectrophotometer. In antioxidant studies, three different methods were used. DPPH, reducing power, and total antioxidants. Results of the DPPH method showed an average absorption of 67.79% between 2 seasons. In the absorption power reduction method, 62.2% was observed in autumn and 0.98 in spring. In the total antioxidant strength method, by comparing the absorbance of the extract solution with the absorption of ascorbic acid standards at concentrations of 50 to 400 mg/l, the total antioxidant in the autumn was 85.3 and 165.1 µg/ml in the spring.