فهرست مطالب fatemeh peykanheyrati

Assessing the toxic effects of pollutants in the early stages of life of living organism, along with other aspects of aquatic toxicology, helps to better understand toxicity of contaminants and to plan for coping with the conditions created. Aluminum, zinc and copper are some of the trace elements that are increasing in aquatic ecosystems due to human activities. In this study, the acute toxicity of aluminum, copper and zinc were investigated on the survival of the Oreochromis niloticus fish yolk sac larvae and the lethal concentration (LC50-96h) was determined based on the OECD 203 protocol. For this purpose, 200 pieces of larvae with a weight range of 0.0132-0.0156 g and total length of 4.25- 4.75 mm, exposed to different concentrations of aluminum (zero (control), 24, 28.8, 34.56, 41.47, 49.76, 59.71 and 71.65 mg/l), zinc (0 (control), 10, 12, 14.4. 17.28 and 20.73 mg/l) and copper (zero (control), 0.625, 1.25, 2.5, 5 and 10 mg/l) for 96 hours. The mortality was recorded at 24, 48, 72 and 96 hours. The physical and chemical parameters of water were also measured daily. Using probit regression analysis, LC50-96h for aluminum, copper and zinc was 61.839, 1.397 and 14.056 mg/l, respectively. The concentrations were determined at 95% confidence interval in mg / l for aluminum 55.449-67.851, copper 1.157-1.637 and zinc 12.293-16.411. The results, proved that copper was more toxic than zinc and aluminum in tilapia fish larvae.

Phosphorus one of the critical macronutrient that plays an important role in energy transfer, phospholipid and nucleic acids synthesis and biochemical compounds in microalgae cells, as well as plays an important role in the formation and transfer of metabolic energy in ATP and NADP. In this study, the effect of different phosphorus concentration (0, 2, 4, 8 and 16 mg/L) on growth rate and biochemical composition of Isochrysis galbana was investigated. The results showed phosphorus deprivation decreased cell growth, pigments and protein; while carbohydrate and lipid content of I. galbana increased as the phosphorus concentration increased. The highest carbohydrate, protein and lipid content were 23.5, 34.6 and 36.2 % in phosphorus concentrations of 0, 8, 0 mg/L, respectively. Also, by increasing the concentration of phosphorus from 0 to 16 mg/l, the content of C16: 0 (33.96%) and C18: 0 (23.4%) decreased to 27.75% and 14.37%, respectively. The results of this study indicate that phosphorus concentration significantly affects the growth rate and biochemical compositions of I. galbana.

Nowadays, silver nanoparticles have very important application in different industries mainly because of the antimicrobial activity. The purpose of this investigation was to evaluate the possible effects of silver nanoparticles in comparison with the silver ions (as silver nitrate) on some histopathological alterations in gill of rainbow catfish. Eighty-five individual of rainbow Catfish (12 ±0/26 g and 10/7 ± 0/46 cm) were randomly divided into 5 glass tanks (each 100 L) each one was considered as a treatment. The experiment was conducted in 10 days and consisted of five treatments as follows: 1 μg / L silver nanoparticles, 1 μg/L silver nitrate, 20 μg/L silver nanoparticles, 20 μg/L silver nitrate and the control group. At the end of the experiment, the gill tissues were prepared for histological studies. Hyperplasia of gill filaments and gill secondary lamella as well as shortening and looping structures of the secondary lamellae were observed in the gill tissues. Quantitative analysis was done using organ index (Iorg). The Iorg was in the range of 1.33-11.66 were the highest and lowed tissue alternations were observed in the fish which belonged to the highest dose of silver nitrate and control group respectively. The results showed that although silver nanoparticles and silver nitrate have significant adverse effects on gill tissues of rainbow catfish, silver nitrate caused much more structure alterations when compared to similar dose of silver nanoparticle (P