JOURNAL OF MARINE SCIENCES AND TECHNOLOGY
Year:2008 | Volume:7 | Issue:1-2|Papers Count:23

The effect of different levels of astaxanthin was evaluated on the growth indices and survival rate in whiteleg shrimp (Litopenaeus vannamei) of 17.39±0.04g average weight. The experiment was conducted on the basis of a completely randomized design (CRD) with four dietary treatments (0, 50, 100 and 150 mg/kg levels of astaxanthin) in three replications. The shrimp was fed four times daily for 9 weeks at average water temperature of 28±20C, dissolved oxygen 7±0.05 mg/l, salinity 41±1‰ and pH 8.1±0.02, and natural photoperiod regime. Results showed statistically significant differences in weight gain (WG), specific growth rate (SGR), condition factor (CF) and FCR in different treatments compared to the control group. There were no significant differences in biomas, hepatosomatic index (HSI) and survival rate in the different treatments. Diet containing 100mg/kg astaxanthin showed the highest WG (4.85±0.14g), SGR (0.39±0.01), CF (0.95±0.02) and the best FCR (1.88±0.07) compared to other treatments (P‹0.05), but didn’t significantly differ from 50mg/kg treatment. It can, therefore, be concluded that 50mg/kg diet was the best one in terms of growth performance due to the economic advantage.

Effect of two activators by content NaCl 45 mM, KCl 5mM, Tris 2.5 mM, Glycin, 19 mM and NaCl 50 mM to compare with distilled water and their pH was investigated on total duration of sperm motility in Cyprinus carpio. Total duration of sperm motility with two activators to compare with distilled water had got significant difference (p≤0.05). Total duration of sperm motility in activators 1, 2 and distilled water assessed at 129.1±3.2, 124±2.4 and 90.1±1.5 sec respectively. Forward sperm motility in activators 1, 2 and distilled water assessed at 65.1±2.1, 63.2±2.6 and 50.2±1.2 sec respectively. This duration in two activators had not got any significant difference but had got difference with distilled water. The activator with pH=8.5 had got highest duration of sperm motility about 94±0.8 sec and the activator with pH=7 had got lowest duration of sperm motility about 92.2±1.6 sec. Sperm concentration was assessted at 1.5±0.1×109 cell/ml. The correlation between total duration of sperm motility with sperm concentration was negative and significant (r=-0.609) and so the correlation between body weight and total duration of sperm motility was positive and significant (r=0.545).

The effects of dietary nucleotide on the growth performance and some hemolymph parameters of the Pacific white shrimp Litopenaeus vannamei were investigated for a 5-weeks feeding trial. The experiment, carried in triplicate, was conducted in circular PVC tanks of 300 L capacity, filled with 200 L of seawater. Each tank was randomly stocked with 25 individuals of 3.21±0.04 average weight. The shrimp was fed three times a day at 8.00, 14.00 and 20.00 hrs to satiation with dietary nucleotide at 0.2% of feed level, and a blank feed (without nucleotide) as control. Dietary nucleotide brought about significantly improved growth factors such as FCR, SGR, PER, and some hemolymph parameters such as total haemocyte counts, differential haemocyte count (granular, htalin) and total plasma protein (P<0.05); however, no significant differences in survival, carapace length gain and dry feed consumption between the two treatments were evident (P>0.05).

Kutum (Rutilus frisii kutum) is one of the economically most important bony fishes in the Caspian Sea, with the highest catch quota. In this project we investigated some of the changes in organoleptic as well as in chemical deterioration factors (PV meq 2/kg and TVN mg/100gr) while freezing kutum in cold storage for four months. Three fresh specimens and twenty–one frozen specimens were studied for organoleptic factors such as changes in taste, flavor and texture as well as for chemical deterioration factors at -180oC for 15, 30, 45, 60, 80,100 and 120 days. After four months the TVN value of the fresh specimens and frozen specimens at -180oC was 9.85 and 20.04, respectively. However, the PV value in fresh specimens and frozen specimens was 0.55 and 1.98, respectively. Organoleptic tests showed that freezing specimens for 80 days was ideal, but after 80 days (80-120 days) significant qualities of collapse were observable. Results of organoleptic and chemical deterioration factors represent 80 days retention time of these specimens that stored in -18°C temperature.

Fish diversity was studied at 5 stations in Haraz River (one of the major river in southern Caspian Sea) from 1999 to 2000. Of total 522 collected specimens, 20 species in 9 families were identified, most of which belonged to cyprinids. Diversity of resident fish were more than that of migratory ones. Diversity (1.76) and species richness (1.93) indexes increased while species dominance (0.18) decreased toward downstream. According to IUCN species categories, Salmo trutta fario falls in Vulnerable (VU), while Caspiomyzon wagneri, Barbus lacerta, Barbus mursa, Chalcalburnus chalcoides and Vimba vimba fall in Near Threatended (NT). Most fish species of Haraz River are important in terms of sport fishing.

The formation of coastal jets as one of long shore strong currents is dependent on the presence of fronts and as a result of pressure gradients. The turbulence terms and coriolies force are important for this currents. In this research the contact zone of water masses with different characteristics and generation of fronts in which zone was investigated, based on analytical and computational methods. By results of the numerical models, velocity and direction currents in surface and bottom has been evaluated. With comparison of CTD data and satellite images in different zone, velocity and width jets were determined. Then, the change of hydro dynamical and sediment logy conditions due to presence of jets in relation to decay time in each zone was investigated .As a result of this research clearly shows permanent jets with high velocity has formation in density gradients position that set up for reason situation masses water. Seasonal jets formation, as a result of salinity variations due to evaporation in east half of central portion of Caspian sea. So that strong currents in entrance zone of central part to southern part of Caspian sea with speed of 10-12 cm/s has been moved.

The effects of Na+, K+, Ca2+, Mg+2, ratios on semen biological characteristics in 21male samples of kutum (Rutilus frisii kutum) were investigated during spawning migration. All ratios were investigation three treratments Na+ to K+ (1:3-8 Mmol, 2:8-13 Mmol and 3:13-18 Mmol); Na+ to Ca2+ (1:100-400 Mmol, 2:400-700 Mmol and 3:700-1000 Mmol); Na+ to Mg2+(1:80-120 Mmol, 2:120-160 Mmol and 3:160-200 Mmol); K+ to Ca2+ (1:10-40 Mmol, 2: 40-70 Mmol and 3:70-100 Mmol); K+ to Mg2+ (1:3- 19 Mmol, 2:19-35 Mmol and 3:35-51 Mmol); and Ca2+ to Mg2+(1:0.1- 0.3 Mmol, 2:0.3- 0.6 Mmol and 3:0.6- 0.9 Mmol). It was found increase in Na+ to Ca2+ ratio resulted in significant (p<0.05) decrease of sperm duration and spermatocrit. Na+ to Mg2+ ratio effected on Na+ and total protein, K+ to Ca2+ ratio effected on Ca2+ and total protein also K+ to Mg2+ ratio effected on glucose and Mg2+. With regard effect of ions ratio on this parameters, that are sperm quality parameters, so ions ratio with others parameters should be regarded for selection of suitable quality sperm.

Some morphometric characteristics, feeding regime and reproduction of 600 specimens of Capoeta fusca was studied in qanats of central zone of Birjand county (South Khorasan Province, I. R. IRAN) during November 2006 to October 2007. The mean total length and maximum length of fish were 13.5±1.4 cm and 21.5 cm respectively. The length-weight relationships of this fish was described as BW=0.0101×TL2.9 (R2=0.9). The mean relative length of the gut (RLG) was 4.42±0.48, suggesting that this species is an herbivore. Likewise, the mean of the vacuity index was 30.95±5.90, so this fish is classified in relatively gluttonous group. Beside plants as primary food, mollusks, aquatic insects, and some times frog eggs, were found as secondary food items. Based on the gonadosomatic index (GSI), the reproduction period of this species begins from March and lasts to May. Variations of gastrosomatic index (GI) showed that, feeding is correlated with reproduction. Measurement of salinity resistance in 96 fish specimen showed that this species can withstand up to 10 ppt of salinity.

In this paper annual and small duration time series of Caspian Sea level fluctuations were modeled using Topex/Poseidon and Jason- 1 altimetry data by statistical methods from September 1992 to September 2007” To take into consideration crossover points of ground tracks, Caspian Sea covered with seven crossover passes. By means of principal component analysis technique, seven time series converted into one series. The Caspian sea level changes showed rising at the rate of +13.7 cm/yr between January 1993 and June 1995. However, by June 1995, the sea level started to drop abruptly, a trend was still observed in January 2001. From middle 1995 to March 1996 the rate of the Caspian Sea level drop was −34.0 cm/yr, and later it decreased a rate −29.3 cm/yr (June 1996- April 1997). From July 1998 to January 2001 rate of sea level decrease was −5.1 cm/yr. From January 2001 to March 2007 the sea level was rising at the rate of +5.5 cm/yr. With comparison of altimetry and level gages data in several stations we could observe high correlations. Correlation between altimetry and level gages data in Anzali, oil stokes station and mean of three stations in north part of Caspian Sea (Machachkala, Krasnovodsk and fort- Shevchenko) was 95.6, 97.3 and 77.3 percent respectively.

Effects of UV-B radiation on skin structure and mortality was investigated in newly hatched larvae that were exposed to different doses of UV-B radiation (68.75 and 94. 83 mw/cm2) for 15 minute (between 13:00-13:15) once a day in laboratory condition. Eggs without UV-B exposure served as control. Aquariums were covered with black plastic covers which prevented reception of any solar light by eggs and larvae. Period experiment continues 9 days. In both UV-B treatments, all of the larvae died within 9 days. No mortality was observed in control group. Mortality in days 1 to 6 was low but significantly increased during days 7 to 9. In histological studies of UV-B treatments were observed that the number of mucus cells reduced as a caused by UV-B exposure in 1 to 5 days. We suggest that this decrease is due to secreting of mucus for protection again UV-B radiation, as result decrease in the its number, followed by increased at 7 days and again were decreased significantly in 8 and 9 days than early days. Their size was small. The number of mucous cells was reduced in control treatment. Alteration process of percentage of mucus-secreting cells in UV-B treatments were inverse the number of mucus cells alterations. Epidermis thickness also in UV-B treatments increased in 1 to 7 days and decreased in 8 and 9 days that was due to epidermis destroy. Epidermis thickness was increased in control treatment but this alteration was not significant in each treatments. Alterations among different treatments were not remarkable but there were significant difference between treatments and control. UV-B radiation also induced necrosis, sunburn cells and lifting epidermis from basal membrane and increased melanin pigments. Our results indicated that UV-B radiation has significant effects on survival rate, epidermal thickness, percentage of mucus secreting cells, necrosis, sunburn and melanin pigments. Four to six days assumed for the regeneration time of goblet cells in different fish species. In our experiment larvae have enough time to replace the mucus cells, but skin damages were so much that don’t have compensate by mucus cells generation.

For commercial production of The oriental river prawn within a short period under control conditions, knowledge of macro-nutrients, especially protein, is essential. Because there is limited information regarding nutrient requirements of the river prawn, hence an experiment of 8 weeks duration was conducted in order to find out the optimum level of protein. Four treatments with levels of 20, 25, 30 and 35 percent with isocaloric digestible energy (DE2800 kcal/kg/diet) were formulated. Each treatment was conducted in triplicate. Three hundred and sixty (360) juvenile prawn (of size 1.4±0.4g) were randomly distributed between 12 fiberglass tanks of 500 liter capacity. The juvenile shrimps were fed at 10% of body weight four times daily (at 9, 12, 15 and 18 hrs). Nutritional responses in terms of weight gain (WG), survival rate (SR), food conversion ratio (FCR), specific growth rate (SGR) and protein efficiency ratio (PER) improved in treatments 3 and 4 (with 25 and 30% protein level) and showed significantly different with other treatments (P<0.05).The treatment one (1) with lowest protein level showed lack of improvement in all growth factors and significant improvement (P<0.05) with the other treatments. The composition of the body carcasses, like protein, lipid mineral and moisture, showed no improvement in treatment 1 and a significantly different with other treatments (P<0.05); but treatments 2, 3 and 4 they did not show noticeable significant differences in body carcasses’ composition (P>0.05). In general, the treatment 3 with 30% protein level was shown to be the most reliable one.

Investigation of osmotic, hormonal and ionic regulation in a culture medium of fresh brackish water is very important for comparison with other conventional media. Osmo-ion regulation in 74 specimens of Great sturgeon (Huso huso) aged 4 and 5 years, reared in brackish water pools (12-17 ppt) in Bafgh, Iran, were examined during a sampling period of one-year. Cortisol level was measured by Radio Immunoassay (RIA), glucose by an auto-analyser, calcium and magnesium by a spectrophotometer, and sodium and potassium by a flame photometer. The osmotic pressure and salinity were determined by digital osmometer and refractometer, respectively. In regard to calcium, magnesium, potassium and sodium, significant inverted correlation was found only between calcium and osmosis. In fact, There was a distinct inverted correlation between salinity and osmosis. Therefore, an increase in salinity and calcium levels resulted in decrease of osmosis. These results indicate that salinity is a main factor for osmo-ion regulation in the samples examined; the higher the salinity the more osmo-ion regulation was exhibited, indicating that brackish water is a suitable culture medium for Great sturgeon.