JOURNAL OF MARINE SCIENCES AND TECHNOLOGY
Year:2002 | Volume:1 | Issue:4|Papers Count:11

One of the facing problems in Urumia Lake is the construction of a connecting way on it. Because of the importance of the problem, different activities have been performed in this relation. However, due to specific conditions of the lake, proposed or applied solutions were less successful. Construction of a concrete floating bridge as a new alternative for connecting two sides of the lake may be a good solution. Thus, it is very important to review and assess the specifications and characteristics of this special type of bridge as well as to perform a feasibility study about the possibility of using such a bridge as an important high traffic connecting way.In this paper, the use of floating bridges from the ancient times to present is briefly reviewed. The developments resulted in construction of modem concrete floating bridges is discussed, along with their unique design requirements. Then, the characteristics including: hydraulical and hydrodynamical conditions, geometry, structural aspects, anchorage system and construction time and cost, of several of these bridges are compared. Finally, the possibility of usage of a concrete floating bridge in Urumia Lake, its advantages and disadvantages are discussed.

Chironomid community in the southern coast of the Caspian Sea was investigated. Samples were collected with a Van veen grab in summer 1994 and spring 1995, at 16 sites of 10, 20, 50 and l00m depths located along the benthal zone in the southern shoreline. Chironomid larvae were taken from samples and preserved. The preserved material was examined microscopically.All the studied larvae belonging to the southern coast of the Caspian Sea were identified as Chironomus albidus.

This survey was conducted in order to study the relationship between the invasion of the comb-jelly, M. leidyi and the anchovy kilka catch decline along the southern coasts of the Caspian Sea. Dietry analysis was conducted on the kilka (Clupeonnela engrauliformis) and comb-jelly from August 2001 to October 2002 in the coastal water near Babolsar and Noushahr of Mazandaran. The comb-jelly was caught by plankton net from 5-10m and 15m depths, and the kilka was caught by fisheries boat. Samples of comb-Jelly were fixed in 96% ethanol.In order to study the comb-jelly's digestive system, some live samples were directly studied under the fluorescence microscope which was connected to a computer. Also, gut contents of both species were studied and dietary overlap between them were calculated by Schoener index.We found that the diet of both species were similar. The Schoener index analysis reflected these similarities, for which the highest of 84%, and the lowest of 85% were recorded in Babolsar and Noushahr samples, respectively. Results of this study suggest that the comb-jelly and kilka have a similar feeding niche and the decline in anchovy kilka stocks is the result of competition between them.

The effect of oblique waves on a stony berm breakwater was investigated. The research was conducted using the physical model in the research-pool of the Soil Protection and Watershed Research Center of Jahad-e Keshavarzi Ministry. The type of wave used throughout the experiment was irregular with an energy spectrum of JONSWAP. In this experiment, waves were generated in two direction of 23° and 68° in relation to the centerline of breakwater (CL), with limited heights of the main wave, and 12 second breakwater head. The numbers of damages were computed. The gained data were separately drawn to show the effect of wave height, duration of storm, and the angle of radiation on the stability of breakwater head. Limits with equal damage numbers for the direction of wave radiation of 68° were drawn and the process of displacement of these limits were studied with changing height of the main wave. With the increase of the main height of radiant wave in two directions of 23° and 68°, the value of damage numbers increased and therefore the change of breakwater head increased, too.

Fresh kilka anchovy (Clupeonella engrauliformis) was frozen and stored at -18°C and -30°C. Some qualitative characteristics of samples such as moisture (M), total lipid (TL), peroxide value (PV), index of thiobarbituric acid (TBA) and free fatty acid (FFA) in different periods of frozen storage (0, 2, 4, 6 and 8 months) were determined.Statistical analysis showed significant increase (P≤0.05) of PV and FFA and significant decrease of TL in each temperature in relation to time of storage. Based on the statistical result, the storage at -30°C was selected for its higher quality of lipids.

Acute toxicity and effects of diazinon on some hematological parameters of Acipenser guldenstadti of 12±2 g body weight were studied under static water quality conditions at 22±10c. The values of 6.15, 5.15, 5.11 and 5.09 mg/L were calculated as LC50 after 24, 48, 72 and 96 hours, respectively, while those of LC50 were calculated 7.21, 6.70, 6.13 and 6.09 mg/L, respectively. The affected fish were paralysed showing restless, cramp movements, loss of coordination and orientation in water column. Fish then turned on the flank and swam in half-circles followed by sudden movements and fin tremor. Also, darkening of dorsal body surface and block of respiratory movements were observed before fish death in a short time. After 96 hours exposing fish of 12 g body weight to LC50 concentration of the toxicant (6.09 mg/L), hematological indices of erythrocyte (RBC), haematocrit (PCV), hemoglobin (Hb), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), leukocyte (WBC) and lymphocyte counts were significantly lower than control (P<0.05), while there was a significant increase in values of neutrophiles and monocytes of test group compared to control one (P<0.05). Also, there was no significant difference in the levels of mean corpuscular hemoglobin concentration (MCHC), leucocryte, eosinophile and immature neutrophile bewteen test and control groups (P>0.05). Also, the levels of alanine aminotransferase (ALT), alkaline phosphatase (ALP), lactate dehydrogenase (LDH), aspartate aminotransferase (AST) and total protein were significantly lower in fish exposed to the toxicant compared to control fish (P<0.05), while level of glucose was significantly higher in experimental fish (P<0.05).

The effect of L-carnitine at concentration of 0, 400, 800, and 1200 mg per kilogram of dry feed on the growth and body composition of kutum roach fry, Rutilus frisii kutum, of 275 mg initial weight was studied for 56 days. The experiment was conducted in triplicate, and each experimental tank contained 300 fry. Feeding varied between 7 to 12% of biomass during the experiment. Although no significant difference on growth data at various concentrations of L-carnitine was found (P>0.05), the fry fed with 800 mg L-carnitine per kilogram of dry feed showed a relatively better performance. Also, no significant difference was found in the levels of body protein and fat (p>0.05) at various concentrations of L-carnitine.

Barbus are valuable fishes in the Caspian Sea, and Barbus capito is one of the commercial species. In the present research, a total of 207 specimens from 25 sampling stations in Gilan Province coasts in the years 2001-2002 were biologically studied in terms of their growth, reproduction and feeding. The following biological factors were recorded and analyzed: Length-weight average variations in different age and sex groups, length-weight relationship, growth coefficient, gonadosomatic index variation, sex ratio, average fecundity, sexual maturation stages, gastrosomatic and fatness indexes, relative length of intestine, stomach vacuity index, hepatosomatic index, accumulation of fat around digestive tract. Relation between length and weight was logarithmic; the L ∞ was found to be 73.7 centimeters and the growth coefficient was equal to 0.3254. Sex ratio of male to female was 3:1 gonadosomatic index peaked in reproduction season and was related to feeding intensity and hepatosomatic indexes. Relation between feeding intensity index and gastrosomatic index was direct, while to vacuity index was inverse.

This study was conducted to determine dietary protein requirement of juvenile beluga with emphasis on amino acids balance. In this experiment six isocaloric diets with different levels of protein (25, 30, 35, 40, 45 and 50 percent) prepared by using accessible materials. Juvenile beluga with an initial body weight of 100±10 g was satiably fed during an 8-week experiment. Analysis of variance (One Way ANOVA) and Duncan's Multiple Range Test suggested that growth performance was significantly affected by different levels of dietary protein (P<0.01). The growth performance indicators such as percent of weight gain and specific growth rate increased as dietary protein increased from 25 to 50 percent, whereas there was no significant effect on feed conversion ratio, protein efficiency ratio, net protein utilization and cost index.The maximum and minimum mean of weight gain, specific growth rate and yield occurred at 50 percent and 25 percent dietary protein levels, respectively. As there was no significant difference (P<0.01) in feed conversion ratio and cost index between the diets having different protein levels, the protein level of 45-50% is, therefore, recommended for juvenile beluga.

Kilka meat which in terms of its nutritional value is as good as red and white meats, can be utilized for the production of sausages. After deboning and mincing, the effect of replacement of 5 to 10 percent of kilka meat-without extraction of water soluble proteins from it-on the taste and flavour of sausages which contained 21.5, 26.6 and 32 percent of red meat, was investigated. The taste panel results proved that inclusion of kilka meat without extracting some of its water soluble proteins, cannot be successful.Thus, after partial extraction of water soluble proteins with 2.5 to 3 percent of brine, the kilka meat was included in the production of sausages. In this case, the effect of replacement of red meat with different amounts of kilka meat on the texture, taste and flavour of 60 samples of sausages was studied. The research on the textural properties of kilka sausages showed that if flour and oil indexes were between 0.667-0.878 and 0.382-0.487, respectively, the kilka sausage had a "good" texture; however, if the indexes were 0.335-0.568 and 0.129-0.439, the texture was "loose". Based on the outcome of this study, a sausage contain 61 percent kilka meat is recommended. The percentages of nutrients such as protein, oil, calcium and phosphorous in this sausage were 16.9, 17.4, 0.39-0.48 and 0.22-0.39, respectively.

An analytical method can be used for flow analysis around the simple bodies or with special shapes as a combination of uniform flow, sink and source flows, vortex flow and etc. However, it is not so easy to use flows combination for complex shapes; other methods should, therefore, be used; for example, Panel method in which the body will be covered with some sink, source or vortex series. Then their effects on one another is studied.Unknowns are source and vortex strength of each panel. The goal is to solve n equations and n unknown. So a software has been developed to calculate unknowns at source and vortex panel by getting panel information as input and storing them in a file. To test the software, by analytical and panel methods flow on the circle and elliptic sections of a given object is analyzed. Results are compared in different graphs.Finally, a hydrofoil with specific dimensions when flows hit it has been studied with panel method and by this software.