JOURNAL OF AQUATIC SCIENCES
Year:2010 | Volume:1 | Issue:2|Papers Count:7

With regards to the importance of scale morphology in fish taxonomy, scale ultrastructure of two gobies including Neogobius melanostomus and N. fluviatilis from south Caspian Sea basin of Iran, was studied using scanning electron microscopy. Scales were gathered from below the dorsal fin and head. They were cleaned in potassium hydroxide solution and were prepared for the electron microscopy scanning. Variations are found in scale morphology of both fishes and in different body parts. Ctenoid scales are present on the head and body regions of both fishes. Focus in N. melanostomus is clear and located in the posterior part of scale and has round shape. Circuli are closed to each other and are regular throughout the scale. Radii in this fish are found only on the anterior part of scale and number of primary radii is more than the second and tertiary radii. But focus in N. fluviatilis is located in the center part of scale and is unclear; radii are found on the anterior and lateral regions of scale. Tongues or lobes of the anterior part are distinct in both fishes. Lepidonts are found on circuli on anterior and lateral regions of the scales in both fishes. It seems that focus shape, lepidonts and arrangement of cteni on the scales of those fishes could be used as important taxonomic features.

Nannochloropsis oculata is an important microalgae that is valuable for hatching of marine fishes and culture of rotifer that has many applicants in marine fishes hatchery of Imam Khomeini. Our purpose was determination of growth dynamic of this microalgae in two different conditions. The study of density increasing in indoor (stock) shows that diagram of density for this species is the same as other researches but phases take a longer time. In outdoor cultures at low temperature condition ( lower than optimum temperature for microalgae culture) duration of growth dynamic also take a longer time than optimum condition. Our study confirmed that this microalgae species can be cultured at winter in south of Iran (Bandar Imam Khomeini- Khozestan) is possible but in a longer period. Also, the optimum time for harvesting this microalgae cultures of conditions were studied.

This study was conducted to evaluate effluent pollution of shrimp culture ponds in Delvar and Helleh in Bushehr Province in 1386. Considering that the water supply for ponds is provided from the sea and the effluent is discharged into the sea afterwards, samples from the following areas were taken: the sea water inlet to the site (control), the sea water inlet before entering the ponds, the effluent outlet of the shrimp culture ponds, and the effluent discharge place to the sea. In these stations, dissolved oxygen (DO), pH, chemical oxygen demand (COD), biochemical oxygen demand (BOD), nitrite content, phosphate content, TSS and TDS were measured. Based on the obtained results, there were no change in pH of the sea water and the effluent during the shrimp culture. The decrease of DO in the effluent was quite marked and its content decreased to less than half. The decrease of COD value indicated the entrance of oxidizing organic and inorganic compounds into the effluent. BOD value remarkably increased in outlet effluent of ponds which was due to the entrance of organic and food compounds into the effluent. The sea water's TSS (total suspended solids) (average = 280 mg/litr) slightly decreased before entering the ponds (average = 190 mg/litr) that might have caused by its precipitation over the pathway. But TSS value in outlet effluent remarkably increased (average = 750 mg/litr) and then slightly decreased due to precipitation (average = 650 mg/litr) until entering the sea water. Nitrite and nitrite contents existing in the sea water increased considerably in outlet effluent. Phosphate in the sea water did not markedly change before entering the ponds, but its value in outlet effluent of ponds significantly increased. By making use of an optimized management of ford and water in shrimp culture ponds and also performing the ETS (effluent treatment system), we will be able to reduce the pollution of the effluent to protect our environment and achieve a sustainable development.

Some physical properties of nesting area of hawksbill turtles (Eretmochelys imbricata), such as slope, grain size and status of nests from March (2005) to June (2006), with four selected stations on the Hormoz Island, was evaluated. According to the results, the stations average slope of the stations was 4.11. The highest degree of slope related to station 1, which was 6 degrees. In grain size all the stations except station 1 almost more than 50% which were 0.125 mm (fine sand) and in station 1 it was 0.25mm (medium sand) which was the highest rate (61.2%). Overall, 46 nests were observed and the average depth of nests was 51.5 cm. The highest formation (35.7%) and degradation (34.7%) nest Station No.2 was related to that of other similar gradation, but there were a lot of plants around the stations which can be considered as an important factor in nesting. It can be concluded that the hawksbill turtle, prefers sand grain size display with 25.0-125.0 mm for hatchery.

Fish food decays is one of the farmers problems in the farms, especially in the warm and humid climate. To avoid probable side effects of chemical antioxidants usage in trout food, the green cumin meal for its antioxidants properties were applied. 5 treatment samples with 3.0, 4.5, 6.0, 10.0 and 20g of cumin meal and 1 blank sample without any cumin meal were prepared. All of the samples preserved in the same conditions of trout culture farms along 35 days in Mazandaran Province (Amol). Along this period the average of temperature and humidity evaluated 18ºC and 79 percent respectively. Lipid and peroxide values were amounted before and after preservation period. Results showed that increasing cumin meal in the treatments will result in decreasing peroxide value from 158 in the blank sample to 9.23 ml ekevalance peroxide per 1000 g fat material.

In this study changes in pH and its relation to psychrophilic and mesophilic bacteria in orange-spotted grouper at 0, 3, 6, 9, 12, 15 and 18 days during a 18-day ice storage were investigated. The objective of this study is to measure and freshness assessment of orange spotted grouper by using pH changes as well as the growth of mesophilic and psychrophilic bacteria and limitation in its consumption due to deterioration during ice storage. The amount of pH was increased during different days of storage. According to one-way anova test the average of pH on initial days with all days showed significant difference (p<0.05). Psychrophilic bacteria had more gradual change unlike mesophilic bacteria and became prevalent with duration of ice storage. Mesophilic bacteria had increasing and decreasing fluctuation during storage period so that it was a decreasing of their number at 15th day, but since 18th day, they started to increase. Microbiologcal indices at first and last day of storage showed significant difference (p<0.05). According to the linear regression, pH showed good relation between mesophilic bacteria and storage days (R= 0.96). An increase in pH at different times of ice storage in orange spotted grouper can create favorable condition for the growth and propagation of these bacteria. Our research revealed that after 18 days of ice storage, the bacterial count specially psychrophilic bacteria was measured more than the optimum level (7.72±0.09 log cfu.g). This is an indicator of quality loss and gradual decomposition of orange spotted grouper which makes it undesirable for human consumption.

This research was occurred to investigate some morphometric and meristic characteristics of Rutilus frisii kutum in both Shazdehrood and Shirood rivers during spring 2010 in their reproductive migration period. Totally, 140 specimens were caught and 26 morphometric and 9 meristic characteristics were studied. According to mean difference coefficients of morphometric characteristics for females in Shirood and Shazdehrood were 11.02 and 12.97 while for males they were 10.78 and 13.08, respectively. Although meristic characteristics for females in Shirood and Shazdehrood were 6.49 and 9.27 for males, they were 8.55 and 9.26, respectively. Morphometric data before analysis were standardized to reduce errors of allometric growth. For morphometric and meristic characteristics of females between Shirood and Shazdehrood there were 3 factors which concluded 79.43 and 56.39 percent traits diversity, respectively, while for males there were 8 and 4 factors which indicated 73.79 and 70.25 percent traits diversity. The obtained results from t-test in 35 morphometric and mersitic characteristics in both rivers indicated that for females two morphometric and six mersitic characteristics and for males seven morphometric and four mersitic characteristics had significant differences (p<0.05). Principal Components Analysis showed both morphometric and mersitic characteristics of females and only mersitic characteristics of males showed overlapping, but morphometric characteristics males had no overlapping.