فصلنامه بوم شناسی آبزیان
سال دوم شماره 4 (پیاپی 204، بهار 1392)

As pearling has been banned since 2006 in Persian Gulf¡ growth and mortality rate of Mohar pearl oyster in its old habitats was surveyed in present research. For early survey and identification of habitats of Mohar pearl oyster Pinctada radiata¡ primary sea tours in coastal waters of Lavan Island¡ were done. Two habitats were identified and sampled seasonally from autumn 2011 to summer 2012¡ to investigate Pinctada radiata stock condition. Belt transects and random quadrates method was used in this sampling. Infinity length¡ L∞¡ in Lavan No. 1 (Dardoor) and Lavan No. 2 (Hedabad) habitats was 89.16 and 87.68 mm. Growth constant¡ K¡ estimated 0.34 and 0.44 year-1in that two habitats. The amount of t0 for oysters in Dardoor and Hedabad habitats was -0.36 and -0.28 year and tmax was estimated equal to 8.46 and 6.54 year respectively. Natural mortality constant¡ M¡ was 0.63 and 0.75 year-1 respectively. Analyses of growth constant¡ K¡ revealed that this figure has decrease in these habitats in recent years. Investigation of recruitment plots indicated semi continuous pattern of recruitment in pearl oysters¡ demonstrating that reproduction occurs in almost throughout the year although two peaks of reproduction were observed in summer and winter.

This study was undertaken to determine the concentration of Pb in liver and muscle tissues of Platycephalus indicus fish collected from two creeks Jafari and Behad (Musa estuary, northwestern Persian Gulf) and was conducted to survey influence of total length and sex on accumulation of Pb in fish tissues during Agust 2010. Concentration of Pb in sediments was also measured. Total number of fish and sediment from each creek were respectively 30 and 9 samples. The samples were digested in laboratory according to MOOPAM 1999 instruction and lead concentration (in µg/g d.w.) was analyzed by Inductively Coupled Plasma-Optical Emission Spectrophotometer (ICP-OES). Results of regression showed a negative correlation between concentrations of Pb in liver and total length that reason of this negative correlation can be lesser absorption rate than excretion rate as the fish grows. In term of lead concentration in liver no significant difference was found between male and female (P>0.05) that indicates sex has no effect on accumulation of Pb in liver. Significant difference between studied areas in concentration of Pb in liver and sediment (P

The beach seine fishery is performed regularly along Iranian coasts of the Caspian Sea. The aim of the present study was to determinate of the species composition of beach seine fishery in Golestan Province. Due to the extent of fisheries cooperatives in the study area 7 cooperatives was selected, namely Magtymguly, Niyaz Abad, Yashar, Shayan Aydin, Golestan, Charqly, Norgolestan and Nemune. Sampling was done weekly basis from late September 2009 to late April 2010. The beach seine nets used in this fishing area were 1200m long and mesh size was 30 to 33mm (Bar length). A total of 462680 Kg teleost fish were caught during the 1534 hauls. The CPUE of teleost fish was 298.8 Kg among the selected cooperatives. The highest and lowest CPUE was observed in Yashar (with 207.5 Kg) and Norgolestan cooperatives (462.4 Kg). Data analyses indicate that Golden grey mullet (with 52.6%) and Roach (with 0.02%) have the highest and lowest proportion of total teleost fish catch. The catch composition did not differ significantly between different months (Chi-square test, P>0.05). In Golden grey mullet, Kutum and Common carp 70.75%, 49.36% and 73.68% of specimens caught were larger than fishing standard size respectively, but in Persian sturgeon 96% of fish captured was smaller than fishing standard size. Results of one sample t test showed that mean length of caught target species, except Kutum, have differ significantly with their Lm 50. In the last decade, catch amount of teleost fish have fluctuated and it was lowest in 2009. It could be managed by making regulations for improving fishing selectivity (such as mesh size and other equipment of fishing gears), more prohibition of spatial and temporal fishing, etc.

The impact of rainbow trout farm effluents on water physico-chemical parameters of Ryjab River was investigated. Five stations were considered at different parts of the river. Station 1 located at the headwaters of the river, station 2 after nearly 30 percent of fish farms, station 3 after 60 percent of fish farms, station 4 after the last fish farm and station 5 located one kilometer after the last fish farm. Water physico-chemical parameters including temperature, oxygen, pH, carbon dioxide, electrical conductivity, ammonia, nitrate, nitrite, phosphate, total dissolved solids, biological oxygen demand and chemical oxygen demand were measured every 15 days at different stations from March to February, 2012. The results showed that there was no difference between the study stations in terms of nitrate rate (P>0.05). The fish farm effluent had significant impact on Ryjab water parameters including pH, CO2, oxygen, alkalinity, the total hardness, the electrical conductivity, ammonia, phosphate, TDS, BOD5 and COD (P 0.05). In conclusion, the effluents of rainbow trout farms have caused the pollution of the Ryjab River and the water physico-chemical parameters have changed.

Global warming due to fossil fuel, price increases, environmental pollution resulting from their use and production green house gases caused scientists trying to produce proper fuel, renewable of replacing fossil fuels. The purpose of this study was to determine the conditions of survival, growth, pigments and fatty acid profiles to biodiesel production from cyanobacteria Synechococcus ISC 106 in nitrogen and pH different levels. Sampling was done of Kharg Island. After purification, the samples were cultured in BG11 at temperature 25ºC under a light and pH 7 were kept. Examples were identified of semi- permanent slides and molecular methods. Then the samples were treated under concentrations of 0.25, 0.5, 1 and 1.5 (g/L) NaNO3 and pH 5, 7, 9 growth rate, the amount of chlorophyll pigments, phicobiliprotein were measured.The amount of total fatty acids, fatty acid profiling were measured by FTIR and GC. Comparison of results between treatments showed the best growth conditions in the concentration of 1.5 (g/L) NaNO3 and pH 7 observed. The greatest amount of pigment and production of fatty acids in a concentration of 0.25 (g/L) NaNO3 and pH 9 was found. The maximum content of lipids were measured such as methyl Myrstat (32.46%), methyl palmitate (16.73%), methyl stearate (5.85%), methyl oleat (1.14%), methyl linoleic (0.64%), methyl linolenic (0%) were measured. Our results indicate that increases lipid production rate in the cyanobacteria Synechococcus elongata in environmental stress conditions.

In this study, reproduction cycle of Silver pomfret (Pampus argenteus, Euphrasen, 1788) was examined in the coastal waters of the Persian Gulf waters (Qeshm Island). Sampling was done using gill and fixed net, in 5-10 m depth, during April 2011 to March 2012. At the end of sampling period, 474 fish were collected (292 male and 182 female). Male to female ratio was increased in month of peak spawning (P 0.05) were observed in the oocytes size frequency distribution between different parts of ovary (proximal, middle and distal). Females are most fecund at 24.5-26 cm (SL) and males are most fecund at 20-21.5 cm length class (SL). This species has a prolonged spawning period as extend of April to September. Two peak spawning observed for both sex. The first peak in May and the second peak in July were observed for females and the first peak in June and the second peak in July were observed for males. At the end of experiment, it was concluded that there was no difference between reproduction cycles of Silver pomfret in compare with other repetitious spawning fishes.