JOURNAL OF MARINE SCIENCES AND TECHNOLOGY
Year:2002 | Volume:1 | Issue:3|Papers Count:10

AS a potentially new source of valuable chitin and chitosan, cyst shell of Artemia urmiana was collected from the Lake Urmieh. The Chitin was extracted chemically in 4 steps of demineralization, deproteinization, delipidization and decolorization; then purified with NaCl and CHCOOH solution. The yield efficiency was 28±3 (w/w) % .The chitosan was prepared from chitin through deacetylation method using 50% sodium hydroxide solution (v/v) and 97% ethanol boiled for 4 hours, with a yield efficiency of 60±3% degree of deacetylation (DDA). Chemical structure and composition of chitin and chitosan were obtained by methods of CHN-O - analyzer, Infrared spectroscopy (FTIR), and X-Ray powder diffraction.According to results, chitin contained 7.6%N, 7%H, 48.6%C and its empirical formula was (C7.6.H12.36.No17.7)n. This results for chitosan was 7.6%N, 41.4%C, 6.7%H with empirical formula of (C6.27 .H11.29N1O28.4 ) n. It was concluded that chitin and chitosan could be produced in large amount from cyst shell of Artemia urmiana as a new source.

The biflagellated cells of the alga, Haematococcus pluvialis, is greenish during its growth phase, and turn into reddish cysts, under unfavourable circumstances, due to accumulation of kelocarotenoid astaxanthin. We investigated the effects of the light intensity on the astaxanthin production in two strains isolated in Iran (TMU) and Germany (SAG). Red cysts of these algae were preserved in agar medium. We cultivated, these strains in liquid culture medium under controlled conditions. The results showed transformation of green biflagellated moving cells to green immobile cells and then to red cysts in both strains, followed a different pattern, depending on incubation time and light intensities used. The accumulation of astaxanthin in the TMU strains was 2.5-3 fold more than that of the SAG-strain. This could be interpretedas a specific adaptation of TMU-strain to the habitat with high light intensity, which in turn could be correlated with the increase in the number of cells

Effects of washing cycle (1,2 and 3 cycles) and time (5,10 and 15 min) and washing media (chilled water and alkalin-salin washing Containing 0.15% NaCl and 0.2% NaHC03) on color (L*, a* and b*), flavor and odor of Clupeonella engrauliformis were evaluated. The results showed that increasing the washing cycle could improve the color of surimi, and increase in witheness occurred for minced washed with chilled water, but increasing the washing time slowly improved the color of surimi and alkalin -salin washing had a lower effect compared with Chilled water. Increasing the washing cycle and time improved the flavor and odor of mince and alkalin washinghad a grater effect than chilled water. Extraction of 21% protein of mince reduced the flavorand odor intensities.

To investigate the impact of rainbow trout farm on water quality, three farms were selected along the Haraz River. The sampling processes was made twice per day i.e. morning and afternoon in March, May and June at inlet and outlet points of selected farms. Parameters of pH, EC and BOD5 were measured using DO meter, model Multiline F/Set3-WTW. The amount of nutrients vis. NH+4NO-2, NO-3 and H2PO-4were also measured with the help of Ion Chromatograph (HPLC) model Shimadzu-6AV with detector CDD-6A. The result of analyses revealed that the difference between parameter values at inlet and outlet and outlet points varied from 0.15 to 3.92 mg/L, .0.02 to 0.32, 1 to 31 µs/cm, 0.12 to 1.91 mg/L, 0.05 to 0.69 mg/L and 0.09 to 0.67 mg/L for DO, pH, EC, BOD5, NH+4 and NO-3, respectively, whereas the concentration of NO-2 and H2PO-4 was not measurable by the HPLC. A significant correlation was also found between fish density and NH+4 concentration.

Cross-breeding of grass carp and bighead carp resulted into viable hybrid. Artificial propagation was induced by I.P. injection of LRH-A. Percentage of egg fecundity, hatching ratio and active swimming larvae were found to be 88%, 90% and 90%, respectively. Larval development of hybrids during incubation was normal and nearly identical to other Chinese carps until the fifth day. Then they were transferred into 400 m2 ponds for further rearing. The high mortality rate of 60% "vas observed in the first day of feeding, due to the failure in development of gill and mouth of hybrids. During the early life stage, the larvae were zooplankton feeder and then turned to a mixed phyto-zooplankton feeding regime and finally after day 48 were completely phyto feeder. Morphological analysis on color, scales, structure of fins, mouth, body shape, body length, vertebral bones, body ratios and the form of pharyngeal teeth of the hybrid showed significant differences with control fish. Furthermore, blood smears of hybrids indicated different shape and cell volume in the erythrocytes in comparison with control. Chromosomal preparation also indicated that the majority of hybrids were triploid (2n=72) as well as some diploid (2n=48) whereas both the grass carp and bighead carp were totally diploid with 2n=48.The proximate analysis results of hybrids meat showed different amount in protein, fat and ash with control, too.

An efficient numerical model is applied to estimate the detailed storm surge in the Caspian Sea. This model uses an economic fully implicit finite difference shame and variable grid size to solve the depth-averaged equations of motion and the continuity equation. Terms of atmospheric pressure gradient, wind stresses, tidal force, bottom and lateral friction, coriolis force and convective acceleration are all included. Also, this model is included wetting and draining for cells. Thus this can be used to simulate tidal circulation, storm surge and shear induced flow. A variable grid system was used to give better resolution at specified subareas. Model can be easily maintained and adopted for other applications. The model can be run on a personal computer with sufficient efficiency. For the nonlinear system used in this study, the time increment must be determined by experience, and, in general, it is much larger than the time increment used in an explicit scheme. However, one should be careful not to choose too large time increment to misrepresent the variation of applied forces. This model also provides a basic framework for future study on wave induced current because the radiation stress terms can be added into the equations of motion and solved similarly. This paper presents the basic algorithm and the application of this model in the Caspian Sea for estimate wind induced currents and storm surge with including conditions of the Caspian Sea.

Changes in density and biomass of Mnemiopsis leidyi population from three sites of the Iranian coast of the Caspian Sea (Noor area) were studied in upper layers (layers above 5 m depth), during winter, spring and summer of 2002. The lowest biomass was recorded on February 20 and the highest biomass was recorded on May 22 (0.024 g/m3 and 10.037 g/m3, respectively). Also the lowest density was observed on March 17 and the highest density was on May 22 (2.3ind./m3and 203ind./m3, respectively). The lowest mean weight of each individual was observed on February 20 and the highest mean weight was recorded on September 4 (0.008g and 0.123g, respectively). The result of the present study showed that Mnemiopsis leidyi reproduction occurred in spring and summer, but the highest rate of reproduction was recorded in spring. The increase in biomass of ctenophore occurring in spring is due to high rate of reproduction, whereas the biomass changes recorded in summer is due to an increase in growth and weight of each individual. Our results showed that weight and size of Mnemiopsis leidyi increased from March to September and reached the highest level in September.

The biochemical composition of the Caspian Sea ctenophore, Mnemiopsis leidyi. was analysed in terms of total fractions of protein, lipid, ninhydrin-positive substances (NPS), polysaccharides (PS) and low molecular- weight carbohydrates (LMC).The sum of organic substance per garm dry weight was 84.18 mg/g. Protein was the major fraction followed by lipid and NPS. The NPS/ protein and LMC/PS ratios were 0.45 and 0:50 mg/g DM, respectively. Starvation of Mnemiopsis leidyi for one week resulted in reduction of all biochemical fractions, and for 3 weeks, high loss of body weight occurred. The sum of organic substances per gram dry weight after one week starvation was 56.7 mg which was 30% less than the non-starved condition. In unfavorable conditions all biochemical fraction changed simultaneously.