JOURNAL OF MARINE SCIENCES AND TECHNOLOGY
Year:2013 | Volume:11 | Issue:4|Papers Count:13

The effect of garlic essence on growth, feeding indices and chemical body composition was investigated in juveniles of reared beluga (Huso huso). Six diets (one diet without garlic essential oil and antibiotic as in control diet, one diet with 30 mg/kg Oxytetracycline antibiotic and four diets with 50, 100, 150 and 200 mg/kg garlic essence) were prepared and fed to juvenile Beluga with mean weight of 24±1.50 g for 8 weeks. The final weight (FW) and percentage increase in body weight (BWI), Protein Efficiency Ratio (PER), Protein Production Ratio (PPR) and total body protein content were significantly higher in diet with 150 mg/kg garlic essence while, the Food Conversion Ratio (FCR) was significantly lower. This treatment was significantly (P<0.05) better than other treatments. In conclusion, adding 150mg/kg garlic essential oil to beluga juvenile diet is proposed to improve growth performance, feeding indices and chemical body composition.

The aim of the present study was to evaluate dissolved oxygen concentration on growth and muscle composition of great sturgeon, Huso huso, in two weight groups (initial weight 280.9±49.2 and 1217.9±138.1). Oxygen treatments including hypoxia (2-3 mg/l), normoxia (5-6 mg/l) and hyperoxia (9-10 mg/l) were prepared by adjusting inflowing water and utilizing equipments for providing hyperoxygenation (pure oxygen injection). Fish were acclimated to experimental tank for one week and each group were randomly distributed in 9 tanks (3 fish per tank in higher weight group and 6 fish per tank for lower one) for 8 weeks. There were significant differences between treatments for Wt, WG, BWI, FI and SGR in both groups and CF in higher weight group (P<0.05). Muscle composition analysis showed no significant differences among the treatments in lower weight group (P>0.05) but moisture and fat content showed significant differences between treatments in higher weight group (P<0.05). Results indicated that high oxygen level has a direct effect on growth performance of great sturgeon and hence the use of a high oxygen level is recommended for the culture of great sturgeon.

The present study carried out to assess the effects of Benzo-a-Pyren (BaP), as an important Polycyclic Aromatic Hydrocarbon (PAH) on the plasma levels of cortisol and triiodothyronine (T3) hormones in male Seabream, Acanthopagrus latus (Sparidea). To assess the acute effects of BaP on the endocrine system, a group of fish was injected with dissolved BaP in sunflower oil (50mg/kg BaP in 2mg/l oil according to the body weight). Other fishes were injected with 2mg/l body weight as controls. Blood samples from both groups were collected 3 hours after injection. In another protocol, the chronic effects of BaP on the plasma levels of cortisol and T3 were assessed. Another group of fish was implanted with 50mg/kg BaP in 10ml/g coconut oil in respect to fish body weight. A control group was implanted with the same amount of oil without the BaP. Blood samples were collected from both implanted groups (treatment and control) after 72 hours. Plasma levels of cortisol in yellowfin Seabream increased during both short time and long time exposure but T3 levels in the plasma decreased during the chronic stress of BaP exposure. It seems that the cortisol levels are elevated to meet the increased energy requirement under the acute and chronic stress conditions by direct effect on glyconeogenesis and fast blood sugar level to be consumed by cells. T3 levels may be affected by inhibitory effect of Aryl hydrocarbon receptors (AhRs) which decreased it during long term exposure.

Biomass and density of green tiger prawn were estimated in Bushehr waters during July - August in 2004, 2005 and 2006. Study area was located from Motaf (27 30 N and 51 50 E) to Daylam waters (30 00 N and 50 00 E) in the northern part of the Iranian waters of the Persian Gulf with about 2000 nm limit. 45 stations in 15 transects were selected in the waters less than 10 m, 10-20 m and 20-30 m deep. Sampling was done by bottom trawl net. The maximum catch per unit effort (CPUE) of green tiger prawn was obtained in south area. From middle to end of shrimp fishery season (August) CPUE increased in the northern area. Based on our estimations, the initial total shrimp biomass in the south area was 674, 1024 and 873 tons in 2004, 2005 and 2006, the percentage biomass being 77, 75 and 86, respectively.Investigation of the shrimp concentration in the Bushehr waters showed that the green tiger prawns entered the fishing grounds from the southeastern parts of Bushehr waters, and Motaf, Nakhilu, Rase khan and Rod mond could be considered the initial appearance zones. Dense schools of green tiger prawns were observed above 10 meter depth in late June and early July and at 20-30meter depth in late July.

Clean-up of ecosystems from heavy metals are essential, because heavy metals are not biodegradable. This study was carried out to investigate the mangrove role in accumulation or sequestration of heavy metals (Cu, Pb, Ni, Cd and Zn) from their surrounding environment. For this purpose, samples of sediment and mangrove roots and leaves were taken from Mangrove habitats in Bandar Imam Khomeini during winter. Samples of plant tissue were digested in HNO3 and H2O2(5:1) and sediment samples were digested in HNO3 and HClO4 (4:1) and their metals content was measured using atomic absorption spectrophotometry. Mean of copper concentrations in the sediment, root and leaf of different stations was 29.06, 11.3 and 6.36 mg/g, Pb: 23.68, 11.87 and 9.55 mg/g, Ni: 97.49, 7.35 and 5.01 mg/g, Cd: 5.62, 3.27 and 2.64 mg/g and Zn: 79.97, 32.07 and 18.86 respectively. Mean of heavy metals in area sediment were smaller than world sediment and crust. Also, calculation of marine pollution index was revealed that there are most of heavy metals in mangrove habitat 1.

Wave spectrum provides a frequency domain description of the sea surface elevation and the stochastic process. Depending on the nature of the sea state they will be described by different shapes of spectra. Information about the spectral characteristics of waves such as significant wave height, peak wave period and wave spectral energy density are the basic needs of many scientific and engineering activities. In this study the raw wave's data measured by the ADCP in the Asalouye from April 2006 to April 2007 are analyzed. Due to the need to convert the analyzed data into the frequency spectrum through the Fast Fourier Transform, certain considerations are made in analyses. Time series data obtained are classified, and after quality control, these data are used to obtain spectral energy density. The smoothed measured spectrum is compared with some various wave spectra estimated based on theoretical formulations such as Jonswap-Bretschneider-Ochi-Wallop spectra. Results of this study shows that the JONSWAP spectrum is in a good agreement with the measured spectrum. Root mean square values between maximum spectral energy obtained from measured and estimated by JONSWAP is less than other spectral models. It is also found that the spectrum of the region of study is predominant single peak. Furthermore directional wave spectrum is determined by using frequency spectrum based on Longuet-Higgins theory.

Artemia nauplii, despite their marine origin, have a good potential for application in the freshwater ornamental fish culture. In this study, Artemia urmiana and A. franciscana were used for feeding Guppy (Poecilia reticulata Peters) larvae. Newly hatched nauplii at three different densities of 3, 6, and 12 ind./ml as live feed were compared for measuring larval ingestion rate. Results showed that type and density of Artemia nauplii had significant effects on ingestion rate (P<0.05). The average ingestion rate in larvae which were maintained at 12 hours starvation (first set of experiment) were 36, 244, and 664 ind./larvae/day for A. urmiana, 160, 480, and 880 ind./larvae/day for A. fransiscana at densities of 3, 6, and 12 ind./ml, respectively. The average ingestion rate of guppy larvae with 24, 48 and 72 hours feeding preconditions (2nd, 3rd and 4th set of experiment) significantly (P<0.05) decreased. After starvation, the ingestion rate of guppy larvae fed A. urmiana ranged between 22-54, 86-102, and 148-188 ind./larvae/day, for A. franciscana 66-100, 100-260, and 200-224 ind./larvae/day at 3, 6, and 12 ind./ml, respectively. The use of suitable densities of 6 and 12 ind./ml from Artemia nauplii could increase efficiency of utilization and also improve guppy larvae production.

The present investigation is based on separation and identification of Planktonic Poecilostomatoida in Bahrakan waters during July, August, October of 2010 and December, February, April of 2011. In the present study the order Poecilostomatida was represented by 3 species, Corycaeus andrewsi and Sapphirina nigromaculata and Saphirella-like copepodid. Abundance of each species was estimated in sampling months. The highest density of Poecilostomatoid copepods were recorded in August and October 2010. C. andrewsiwith relative frequency of 73% was the dominant species among Poecilostomatoida and the highest abundance was observed in October 2010. Saphirella-like copepodid was observed in all sampling months. Maximum abundance of this species was in August and October 2010 and this report is the first report of this species in the Persian Gulf. There was a significant positive correlation coefficient between density of C. andrewsi and salinity (P<0.05) but there was no significant correlation was observed between the other species and water parameters.

Rabbit fish (Siganus javus) is a valuable species and is considered a potential fish for aquaculture. . Macroscopic and microscopic studies of tissues facilitate the development of biologic and histopathologic knowledge about the species. This study investigates the anatomical feature of digestive tract and histological characteristics of esophagus in rabbit fish through the necropsy of 10 rabbit fish and subsequent 10% formaldehyde solution fixation and tissue processing of esophagus for H&E staining protocol. The length of digestive tract was 45±5 cm (mean ± SD) which comprised oral cavity, throat, esophagus, stomach, pyloric caeca, duodenum, jejunum, caudal part, rectum and the ending part of intestine. Two appendixes called pyloric caeca were observed at the endof stomach. Microscopic studies of esophagus revealed four layer structure composed of mucosa, sub mucosa, muscularis layer and serosa. A numerous spiral folding existed in the mucosal part which surrounded the lumen of the tube and were covered by stratified squamous cell epithelium.

In order to investigate heavy metals contamination in Bushehr costs, 5 different stations including ports and estuaries were studied. 3 sediment samples were collected from each station during winter 2009 and summer 2010. The samples were oven dried and acid digested and their heavy metals content was analyzed using atomic absorption spectrophotometer. Results showed that the concentrations of Cu, Ni, Pb and Cd in the sediment were 14.54, 55.31, 15.13 and .76 mg/g dry weight respectively. Except for cd, the concentration of metals within various stations was significantly different during winter (P<0.05). Seasonal changes influenced metals level in the sediment so that their concentration in winter was less than summer. Generally the concentrations of studied metals appeared within the range of other researches in the Persian gulf region and less than proposed standards for sediment quality. Among studied stations, Bandar Rig and Shif exhibited higher concentrations of metals.