Journal of the Persian Gulf (Marine Science)
Volume:1 Issue: 2, Winter 2010

Effects of artificial diets on growth, spawning performance, egg and larval biochemical compositions and quality of Acanthopagrus latus in the Persian Gulf were studied. Nine diets representing a combination of three protein levels (40, 50 and 60%) and three energy levels (22.5, 23.5 and 24.5 MJ GE/Kg) were tested in triplicates. Each tank was stocked with 10 fish with a sex ratio of 1:1 and with an average weight of 415g and 236g for females and males, respectively. Fish were fed to satiation, twice daily. The growth of Acanthopagrus latus broodstock was not significantly affected (P>0.05) by dietary protein and energy levels. Biometry, relative fecundity and survival rate and crude protein and lipid of eggs, hatchling and 3 day post-hatch (3DPH) larvae were significantly affected (P<0.05), but spawning performance and body composition of broodstock, with the exception of body crude protein and lipid were not significantly affected by dietary protein and energy levels. This study revealed the best spawning performances of A. latus broodstock were achieved at 40% dietary protein and 23.5 MJ GE/Kg dietary energy.

Stock assessment and reproductive biology of the blue swimming crab, Portunus pelagicus, in Bandar Abbas coastal waters was conducted from August 2006 to July 2007. A total of 424 male and 348 female crabs were taken to the laboratory for length, weight and reproductive biometry. Estimate of growth parameter of crab showed t asymptotic carapace width (CW∞) was 172.5 mm, the curvature parameter, K(year-1) was 0.98, total mortality coefficient, Z(year-1) was 2.13, natural mortality coefficient, M (year-1) was 1.05 and the fishing mortality coefficient, F(year-1) was 1.08 then the exploitation rate, E (year-1) was 0.51. Results showed the sex ratio was 1:1.2 with 46.1% female throughout the year. All four stages of ovarian development were observed throughout the year. The Gonad Somatic Index (GSI) monthly mean values ranged between 2.05 to 2.97%. The highest values of GSI were recorded in December. Carapace width of ovigerous crabs varied from 32 to 173 mm. This crab spawned all year round with a spawning peak in December. The fecundity of ovigerous crabs ranged from 277421 to 1114348 eggs, with average fecundity of 662978 eggs. The minimum carapace width (CW) of sexually matured female crabs was 32-151 mm.

Aquatic environments receive significant levels of chemical contaminants generated by human activities. Among these pollutants, we noticed the xenobiotics known as reproductive toxicants and endocrine disruptors. The endocrine disruption in wildlife has been the subject of many reviews and workshops in recent years. Field observations of reproductively abnormal organisms and population declines in polluted sites stimulated major research efforts to understand links between environmental pollution and health problems. Laboratory studies evidenced that many compounds can interfere with the synthesis, secretion, transport, metabolism, mechanism of action or clearance of natural hormones responsible for the maintenance of homeostasis and the regulation of developmental processes. These chemicals are thus defined as Endocrine Disrupting Compounds (EDC), and a list of more than 500 known or suspected EDC has been established by the European Community, such as numerous pesticides, industrial chemicals, and commercial products that have been released into the environment. Of particular importance are those that mimic estrogens and androgens (and their antagonists), because of their central role in reproductive function. Estrogens are substances both natural and synthetic that mimic the effect of the female estrogenic hormone in the body and impart estrogenic activity. Because of this effect, they potentially can disrupt the endocrine system in the exposed aquatic species. Human wastes are a major source of estrogens in the environment, too. These wastes are treated in wastewater treatment plants where some of the estrogens are removed, and the rest is discharged in the effluent. Other sources of estrogenic compounds include birth control pills and chemicals like detergents. It is important to be able to reduce their concentrations and it would be ideal if this can be achieved using available existing treatment processes. Both natural and synthetic estrogens released in the marine environment by the wastewater treatment plants are suspected to interfere with the exposed endocrine systems of aquatic species. In fact, they mimic the effect of the endogenous hormone and therefore, can disrupt the endocrine systems of exposed species and the reproductive systems of aquatic fauna. To understand their environmental fate, the estrogenic activity was studied by using the Yeast Estrogenic Screening (YES) bioassay. This bioassay has been validated in the detection of a wide range of estrogenic receptor agonists. The present work is based on in situ studies. Different compartments were used: the effluents of a wastewater treatment plant, the sea water, the sediment and the clam Ruditapes decussatus. A reverse phase HPLC method was used to identify the nature of estrogenic components. Some observed histological results showing hermaphroditic cases and parasites are also discussed in this paper.

Sea water samples were collected from 32 stations in the southern part of the Persian Gulf and the Gulf of Oman during winter of 1987. Surface water of the Persian Gulf exhibited wide range and higher values of salinity (37.15-43.95, mean 40.02%) compared with lower values and narrow range (36.58-36.95, mean 36.74%) in the Gulf of Oman.Surface salinity did not reflect any significant relationship with nutrients and organic and inorganic carbon except, silicate which showed an increase in concentration with decreasing values of salinity (r= -065, p<0.01) in the Persian Gulf waters.The Gulf of Oman exhibited higher levels of phosphate (0.08-1.65, mean 0.57 µ moles/L), nitrate (0.08-3.44, mean 0.78 µ moles/L) and silicate (2.49-22.47, mean 6.37 µ moles/L) than the surface water of the southern Persian Gulf, while inorganic carbon (7.5-22.6, mean 13.62 mg/L) and organic carbon (2.1-14.6, mean 6.37 mg/L) of the Gulf of Oman showed nearly comparable results with those of the Persian Gulf,respectively. Atomic ratio of the elements P:N:Si for the surface water showed similar values 1:2.2:11.1 and 1:2.7:11.8 for the Persian Gulf and the Gulf of Oman, respectively, indicating N is the limiting nutrient for this area.The presence of a shallow Oxygen minimum in the Gulf of Oman (0.23-1.30 m1/L) at depth 140-370 m and t values (25.51-26.60) coincide with the layer of maximum PO4 (1.06-2.23 µ moles/L), NO3 (3.39-19.33 µ moles/L), SiO3 (12.54-29.51 µ moles/L) and PCO2 which could be resulted from mineralization of organic matter.Water mass of Gulf origin was identified at 190-300 m in the Gulf of Oman that exhibit higher density levels 26.05-26.74 and medium concentrations of organic carbon.The nutrients, inorganic and organic carbon budget in the Persian Gulf waters were evaluated as 42608, 20165, 227909, 3395×103 and 4943×103 Ton/year for phosphate, nitrate, silicate, organic and inorganic carbon, respectively, representing the net gain to the Persian Gulf water.

On the basis of the continuity equation and the Bernoulli equation in the steady form, a differential equation is developed to evaluate the successive water levels within compartments of an upright perforated wave absorber. Then the initial and boundary conditions are introduced and the differential equation is solved as an initial value problem. Finally the reflection coefficient from the wave absorber is calculated by establishing a balance bet ween the rates of energy dissipated, the energy propagation and the energy reflected of the incident waves. The results of numerical model are verified by experimental tests with regular waves. A new non-dimensional parameter is introduced to characterise the hydraulic performance of the upright perforated wave absorber. It is shown that the rate of wave dissipation through the absorber decreases as this parameter increases.

In this study, concentrations of mercury (Hg) and 16 other elements as well as methylmercury speciation were quantified in muscle and liver of two commercial fish species. It was also our intention to evaluate potential risks to human health associated with seafood consumption. The fish species, Mullet and Kutum (Caspian White fish) fishes, were obtained from Tonekabon at the Iranian waters of the Caspian Sea. In this investigation fish tissues (muscle and liver) were analyzed to determine Al, As, Be, Cd, Cr, Co, Cu, Fe, Hg, Pb, Mn, Mo, Ni, Sb, Tl, V, Zn and methylmercury. Total mercury concentration in the fish muscles and liver ranged from 0.02 to 0.13 and from 0.03 to 0.06 µg g-1 w.w, respectively. Almost all the elements were more accumulated in the muscle of Mullet than Kutum fish, except for Hg, Pb and Ni. Concentrations of all elements in the muscle of both fishes were lower than the WHO maximum consumption limit in fish muscle. All elements were more accumulated in the fish liver than the muscle tissue, except for mercury in Kutum fish. This study identifies a statistical relationship between metal concentrations and fish sizes and also the relationship between element levels in the fish liver and muscle.