As algae and their concentrations are important factors for mass culture of rotifer, two experiments were conducted to find the effects of two types of algae, Chlorella sp. and Scenedesmus obliquus, and three concentration of chosen algae (0.1 × 106, 1 × 106, and 10 × 106 cells/mL) on growth and fatty acid composition of freshwater rotifer, Brachionus calyciflorus. The result of the first experiment showed that the maximum density of rotifer was significantly higher when fed with Chlorella sp. (478 individuals/mL) than fed with S. obliquus (328 individuals/mL). Mean population growth rate (r) was 0.61 and 0.44 for rotifer fed with Chlorella sp. and S. obliquus, respectively. The amount of highly unsaturated fatty acid (HUFA) in rotifer fed with Chlorella sp. (3.32%) was relatively more than those fed with S. obliquus (2.65%). Then, Chlorella sp. was selected based on better performance. In the second experiment, the maximum rotifer density of 108 ± 8, 489 ± 47, and 493 ± 51 individuals/mL was reached after 5 d for the respective Chlorella sp. concentrations; at concentration of 10 × 106 cells/mL, the maximum density of 1820 ± 47 individuals/mL was obtained. Mean growth rate at mentioned concentrations was 0.18, 0.42, and 0.51/d, respectively. Increase in algal concentration was associated with a relative increase in HUFA and decrease in monounsaturated fatty acid.

Measurements of natural radioactivity levels and heavy metals in sediment and soil samples of the Anzali international wetland were carried out by two HPGe-gamma ray spectrometry and atomic absorption spectroscopy techniques. The concentrations of (235)U, (226)Ra, (232)Th, (40)K, and (137)Cs in sediment samples ranged between 1.05 ± 0.51-5.81 ± 0.61, 18.06 ± 0.63-33.36 ± .0.34, 17.57 ± 0.38-45.84 ± 6.23, 371.88 ± 6.36-652.28 ± 11.60, and 0.43 ± 0.06-63.35 ± 0.94 Bq/kg, while in the soil samples they vary between 2.36-5.97, 22.71-38.37, 29.27-42.89, 472.66-533, and 1.05-9.60 Bq/kg for (235)U, (226)Ra, (232)Th, (40)K, and (137)Cs, respectively. Present results are compared with the available literature data and also with the world average values. The radium equivalent activity was well below the defined limit of 370 Bq/kg. The external hazard indices were found to be less than 1, indicating a low dose. Heavy metal concentrations were found to decrease in order as Fe > Mn > Sr > Zn > Cu > Cr > Ni > Pb > Co > Cd. These measurements will serve as background reference levels for the Anzali wetland.

Anzali International wetland is located in the south coast of the Caspian Sea. Physicochemical analysis and zooplankton survey of the wetland were carried out on monthly basis for the period of one year from January 2012 to December 2013 at 9 different stations of Anzali wetland and its related channel to the Caspian Sea. Water temperature of the wetland followed more or less similar trend as that of air temperature. pH determined alkaline nature of the wetland ranging between 7.05 to 9.47, dissolved oxygen was recorded in the range of 3.36 mg/l to 10.51 mg/l while other parameters recorded were water temperature (10 to 23 C), Nitrate (0.48 to 4.36 mg/l), Total Phosphates (0.15 to 0.67 mg/l), Salinity (220 to 692 mg/l), Electrical Conductivity (235 to 1369 µs/cm), TDS (246 to 1971 mg/l), BOD (2 to 36 mg/l) and COD (4 to 74 mg/l). During study period, total 60 species of zooplankton were identified in four main groups such as Protozoa (22 sp.), Rotifera (29 sp.), Copepoda (5 sp.) and Cladocera (4 sp.). The highest numbers of zooplankton were recorded in summer months and lowest in winter which is the second rainy season of this area. The water body is receiving domestic discharge, agricultural run-off and industrial wastes leading to large amount of nutrient inputs to the ecosystem which indicates the eutrophic statue of the wetland. The aim of present study was to investigate the interrelationship between physicochemical factors and zooplankton population in context of their seasonal abundance.

Abstract:The rotifer, Brachionus calyciflorus, was grown with two algae species (Chlorella sp. and Scenedesmus obliquus) at different concentrations (0.1, 1 and 10 × 10 6 cells ml −1 ). The body size (lorica biovolume) of individual rotifer and their egg size were measured when the populations were roughly in the exponential phase of population growth. The body size of the rotifers differed significantly (P < 0.05) among the two algae species used, however this effect was not observed for egg size. The body size of rotifers fed on higher densities of Chlorella sp. (10 × 10 6 cells ml −1 ) was significantly larger than for those fed on lower and medium densities (0.1 and 1 × 10 6 cells ml −1 ). Body size and egg size of rotifers fed with different amounts of Scenedesmus did not differ significantly. The egg size was significantly larger at higher food level of Chlorella. A significantly positive correlation was observed between the adult rotifer body size and their egg size.