نشریه پژوهش های علوم و فنون دریایی
سال نهم شماره 2 (تابستان 1393)

The present study fulfilled to investigate possible changes in the structure of the gills of Flower horn fishes fed diets containing different levels of cow skin hydrolyze. For this purpose, 216 Flower horn fishes with mean weight of 0.95 ± 0.2 g and the mean length of 3.7 ± 0.2 cm were fed for 100 days with levels of 20 percent (T1), 40 percent (T2), 60 percent (T3), 80 percent (T4), 100 percent (T5) replacement hydrolyzed cow skin instead of fish meal. Control diet (T6) had no hydrolyzed cow skin. The results indicated that the gills of fishes fed with level 0, 20 and 40 percent cow skin hydrolyze were healthy and certain symptoms in the gills were not found. In the gills of fishes fed with diet containing 60 percent cow skin hydrolyze, symptoms such as mild hyperplasia in the secondary lamella and mild skin lesions were observed. In some gill tissue samples from treatment (T4) some secondary lamella were wide. In the gill treatment T5, tissue lesions were more. Cutaneous lesions in the secondary lamella, shortage and lengthening of some secondary strings and Aneurysm (hyperemia) in the secondary lamella, were lesions that were observed in the gill tissue samples of treatment T5. From the above findings, it can be concluded that with the increase in cow skin hydrolyze, from levels of 40%, adverse effects in gill tissue was increased.

Caspian Sea and its coastal areas are one of the most important ecosystems. There is great diversity associated with non-biological parameters of water, in this largest lake in the world. In this study the physical and chemical parameters, including nitrates, phosphate, temperature, salinity, dissolved oxygen, transparency, EC and pH were investigated. Sampling was performed in 2008 in thirteen regions from Astara to Khajenafas in the south coastal waters of Caspian Sea. There were three stations in each area and sampling was done from surface waters (5 and 10 m) from each station. In this study, the mean temperature, salinity, pH, EC, water transparency, dissolved oxygen, nitrate and phosphate were 19.6 ° C, 11.8 ppt, 8.7, 17.28 (mm/cm), 82.23 cm, 6.22, 0.061 and 0.014 mg/l, respectively. Maximum and minimum of nitrate levels were 0.154 and 0.007mg/l in Kyashahr and Astara, respectively. The peak level of phosphate concentration (0.062mg/l) was found in Bandar Torkaman and the minimum level (0.001 mg/l) was obtained in the Anzali and Nashtaroud. The results show that concentrations of nitrate and phosphate were higher in south-east compared with south-west coast of the Caspian Sea. There was a significant difference in nitrate concentration in different regions (P< 0.05), but there was no significant difference in the concentration of nutrients in the water column (p>0.05). Results indicate that an increase in level of nitrate was found in compared to previous years. There were positive correlations in dissolved oxygen with nitrate levels and negative correlations with temperature and water transparency. Temperature, salinity and EC had positive correlation and the correlation of temperature with dissolved oxygen was negative.

A comparative study was conducted on composition of protein, lipid and ash and concentration of metals As, Hg and Cd in muscle of Cynoglossus arel from Hendijan area in 2011. Ten samples of Cynoglossus arel were collected using trawl net. Concentration of Hg, As and Cd in the muscle of flat fish was 41.60±7.27, 73.30±7.50 and 189.02±21.40 µgkg-1 ww. Also composition of protein, lipid and ash in the muscle of this fish was determined; 16.58±0.54, 1.04±0.14 and 1.57±0.13 %. Comparison of the results showed significant difference between (P<0.05) concentration of Hg, As and Cd in the muscle of Cynoglossus arel. The highest correlation (R=0.964, P<0.05) was observed in the muscle of Cynoglossus arel between to Cd and As. In this study significant correlation was observed between concentration of Hg, As and Cd with chemical compositions, in the muscle of Cynoglossus arel (P<0.05). The highest correlation (R=0.972, P<0.05) was observed in the muscle of Cynoglossus arel between to As and protein. Also the lowest correlation (R=0.880 P<0.05) was observed in the muscle of Cynoglossus arel between to Hg and protein.

In this study, in order to investigate the acute toxicity of heavy metal copper on blood indices of Silver Carp (Hypophthalmicthys molitrix), 135 fish were exposed to 0, 5 and 10 mg/L of Cu (NO3)2. 24h- LC50 of Cu2+ was 2.5 mg/L. Results showed that white blood cells count (WBC) decreased significantly with the increase of copper concentration (P<0.05). Red blood cells count (RBC) showed no significant difference (P>0.05). Hemoglobin (Hb) levels was decreased with the increase of copper concentration and time (P<0.05). Hematocrit (Hct), mean corpuscular volume (MCV), mean corpuscular hemoglobin concentration (MCHC) and mean corpuscular hemoglobin (MCH) were decreased significantly (P<0.05) with the increase of time. Triglyceride level changed significantly (P<0.05), but cholesterol level didnot. Glucose levels changed significantly with the increase of copper concentration in 12 and 24 hours (P<0.05). Total protein levels decreased significantly at 5 mg/L treatment in 24 hours. Differential count of leukocyte showed significant decrease in lymphocyte and monocyte and significant increase in neutrophil. Based on these results, copper induced significant changes in many blood indices and showed acute toxicity in Silver Carp. Therefore, this species has a low resistance to copper toxicity.

The North Atlantic oscillation (NAO) is one of the effective indices in changing atmospheric situation of northern hemisphere .Southern coastal region of Caspian Sea is affected by different atmospheric systems and teleconnections such as NAO because of its special geographical situation. In this research, precipitation and temperature data of southern coastal region of Caspian Sea are examined for 8 synoptic stations in 1977-2009 period. NAO index data are also received from cpc.noaa.gov website. Precipitation and temperature data were examined with their corresponding NAO indices data by correlation test in monthly and yearly time scales. Furthermore, we found that in this region, when NAO index increases, precipitation will increase and temperature will decrease and vice versa. During recent years, NAO index shows negative trend, so we expect decrease of precipitation and increase of temperature in the region.

The present study investigated sexually disrupting effects of a weak estrogen receptor agonist, nonylphenol ethoxylale on 17 ß – estradiolproduction and ovary tissue in immature Zebra Cichlid (Cichlasoma nigrofasciatum). To determine the effects of nonylphenol ethoxylale ( NPEO ) on female sex hormone of Zebra cichlid, the fish were divided in 3 weight groups ( < 4 g , 4 – 5 g and > 5 g ) and exposed to three concentrations ( 10 – 50 – 100 µg / L ) of NPEO in glass aquariums during 60 days. At an estimated NPEO concentration of 50 and 100 µg / L, 17 ß – estradiol production significantly was increased (P < 0.01). Special changes were showed in 50 µg / L. Estadiol levels were 0.13 – 0.70 ng /ml. This evidence of steroid hormone (17 ß – estradiol) levels showed that nonylphenol ethoxylate (>10 µg / L ) could exert estrogenic effects through gene expression and producting enzymes involving vitellogenesis and lead to production of grown oocytes in 50 µg / L of nonylphenol ethoxylale.

Ten specimen of Vimba vimba persa fish were caught using a bach seine net by local fishermen in December 2013 from the Anzali coasts (Anzali Wetland openings). Samples were transferred to the laboratory and then the fish gender was determined. Biometry of each was done. Samples consisted of 6 female and 4 male. Average length of females and males were 19.21 ± 1.01 and 18.65±0.264 cm respectively and the average weight of females and males were 68.8± 8.160 and 62.9±2.201 gr respectively. Then, 1 gram of every fish muscle was separated and Al, Ni, Cr, Pb were measured in the muscles after chemical digestion using ICP. Hg measurement in muscles was done by atomic absorption using cold vapor method. Each treatment had 3 replicates. The amount of metals in both females and males was as follows Al> Ni> Pb> Hg> Cr. Significant differences between the concentrations of these metals were not observed in both males and females (P≥0.05). By comparing the concentration of studied heavy metals with international standards (WHO, FAO, SAW, FEPA) showed that mercury levels in males and females were 0.22± 0.05 and 0.20±0.06 milligram in kilogram respectively (WHO=0.1-0.5), chromium in both sex was less than 0.01 milligrams in kilogram (WHO=0.15) and lead in males was 0.85± 0.44 and in females were 0.58± 0.36 milligram in kilogram (WHO= O/5-1/5) and each 3 metals were less than the international standard levels. The concentration of Aluminum in males was 1.95±0.51 and in females was 1.23±0.59 milligram in kilogram (SAW=0/03) and Nickel was 1.60±2.00 and 0.766± 0.18 milligram in kilogram in males and females respectively (WHO=0.5-0.6), which exceeded of international standards.

Changes in abundance and biomass of cyanobacteria have been studied in the southern part of the Caspian Sea (the stretch between Tonekabon and Amirabad) in four seasons (spring, summer, autumn, winter) in which samples were taken from five depths of 5, 10, 20, 50 and 100 meters in the stations of Tonekabon, Noshahr, Babolsar and Amirabad. Samples were fixed with formalin (2%) before transferring to the lab for both qualitative and quantitative analyses. The results of this study showed higher abundance and biomass of cyanobacteria in euphotic layer compared to aphotic layer. Temperature, ammonium, nitrate and nitrite levels have shown significant differences.