JOURNAL OF MARINE SCIENCES AND TECHNOLOGY
Year:2007 | Volume:6 | Issue:1-2|Papers Count:11

Concentration of heavy metals Pb, Cu, Cd, Ni, V in blood serum of the Persian sturgeon and their length weight, and age correlation were determined. Samples were collected from the fish landing sites in Guilan and Golestan provinces located in western and eastern parts of the South Caspian Sea during the catch seasons of 2001-2. Analyses were carried out using the flameless atomic absorption for Cu, Cd, Ni, V and flame atomic absorption for Pb. The lowest accumulation was found for Cd and the highest for Cu. Positive correlation between Pb and Ni concentration and fork length and weight was observed (p<0.05). No correlations were observed between heavy metal concentration, age, catch season, and sex of the specimens.

Application of different organic and inorganic coating layers is one of the common ways to protect corrosion of steel marine structures. Appropriate coating operation, adhesion between the primary, middle and the top layers, are necessary for this purpose. Also, the strength of primary layer which exposes to corrosive environment is required. All these processes depend on the chemical and mechanical coatings characteristics. In this research, the laboratory tests and field operation are investigated to find out the efficiency of coating of zinc, ethyl silicate on ST37 in three layers. The results show that these layers are appropriate for the submerging zone in the Persian Gulf. These tests have been performed in NACERPO176-64 standard in Bandar Abbas every week during six mounts.

Five groups of 2+ years rainbow trout brood stock were fed with supplemented diets containing 0.07, 12.46, 33.33, 65.1 and 92.9mg/kg astaxanthin till final sexual maturation. Broods produced egg containing 2.03-29.97 mg/kg astaxanthin; there was significant difference among treatments in egg astaxanthin content (P<0.05). Larval astaxanthin content range was 0.7-7 mg/kg; there was significant difference among treatments in larval astaxanthin content (P<0.05). The astaxanthin content of larvae was far less than egg astaxanthin content, showing low transmission rate from egg to larvae and high conversion rate of astaxanthin to its metabolites during embryonic development. There was no significant difference in transmission rate among treatments (P>0.05).  The regression relationship between diet and egg and also egg and larvae astaxanthin content was significant. According to initial weight and length measurement at the time of active feeding, there was significant difference among treatments in mentioned factors. Treatments containing 5.32 and 0.7 mg/kg yielded highest and lowest average initial weight and length, respectively. According to egg and larval astaxanthin content and also its transmission to larvae, we can conclude that the accumulated astaxanthin in egg can be active during embryonic development and can affect the initial growth. 

The biomass of batoidfishes biomasses (rays and skates) was estimated during November and December 2005 in Hormuzgan provincial waters (between Ras Meidani in the Oman Sea and Ras Naiband in the Persian Gulf). The total biomass was 12454 tons. Furthermore, the estimated biomass for depth layers 10-20, 20-30 and 30-50 meter were 7567, 1966231 and 292 tons, respectively.In addition, the biomass, CPUA and CPUE rates were also evaluated for each species in different depth layers. Himantura gerrardi with 6065 tons in depth layer 10-20 meter and Torpedo sp. with 0.6 ton in depth layer 20-30 meter had maximum and minimum biomass, respectively, among all the specimens. The number per area, mean weight and catch per unit area of batoidfishes in different depth layers were statistically analysed at 95 percent confidence.The number and catch per unit area of Himantura gerrardi significantly differed (P<0.05) between depth layers 30-50 meter and deeper than 50 meter, but not for other species (P>0.05).

Frequency of Lenkoran, Capoeta capoeta gracilis (Keyserlhng, 1861), in Madarsoo stream of Golestan National Park was determined from November 2003 to December 2004 and was compared with results of studies conducted earlier years before the occurrence of two huge floods in 2001 and 2002. The fish samples were collected through electro shocking. The mean catch per unit effort and absolute frequency in this research was 579±824 fish and 2.33±2.6 fish per square meter, respectively, which were significantly (p<0.01) higher than those obtained before the flood occurrence. The lowest and highest frequencies were recorded in Golestan and Sarcheshmeh, respectively. Frequency greatly varied in different sampling months depending on flow speed. Fish frequency and flow speed were inversely related. The reason for higher frequency in this work could, probably, be attributed to algal bloom as the result of flood occurrence.

Some biological aspects of bream (Abramis brama) such as seminal plasma indices (ionic and organic composition) and their relationships with sperm motility were investigated. Seminal plasma contained 59.05±8.27 mmol/l Na+, 1.65±0.354 mmol/l K+, 5.95±1.45 mg/dl Ca2+, 18.36±3.46 mEq/l Mg2+, 0.150±0.055g/dl protein, 29.42±7.17 mg/dl cholesterol and 38.11±8.59 mg/dl glucose. Semen spermatocrit was 35.35±8.06%, pH 7.69±0.227 and duration of spermatozoa movement was 56.30±14.18s. The sodium/potassium and calcium/potassium ratios were 35.78 and 3.60, respectively. Spermatazoa in two out of 10 bream semen samples were motile in seminal plasma.There were no significant correlation between ionic and organic composition of the seminal plasma and sperm motility (p>0.05), but there were significant negative correlation between glucose and spermatocrite (r=-0.785, p<0.01).Consequently, although there were no definite correlations between biochemical and spermatological parameters, it was observed that higher spermatocrite content had negative effect on glucose content.

Population dynamics of buccaneer anchovy, Encrasicholina punctifer, from the Qeshm Island coastal waters was studied during April 2005 to March 2006. The asymptotic length (L¥ and growth coefficient (K) were estimated as 110(mm) and 1.1(yr-1), respectively. The value of to was calculated as -0.19 year, which gives the growth equation for this species as L (t) = 110 (1- exp (-1.1(t-(-0.19))). The minimum and maximum T.L was recorded 33 and 108 (mm), respectively. Total mortality (Z) rate was estimated 3.56yr-1) (r2=0.93) using length-converted catch curve method. The rates of natural mortality (M) on Pauly's empirical equation, fishing mortality (F) and exploitation ratio were estimated 1.29 (yr-1), 2.27 (yr-1) and 0.64, respectively. Four cohorts were annually distinguished on Bhattacharya's method. Length-weight relationship was determined W= 0.000009 L2.9125.

Morphometrical characteristics of the crab, Rhithropanopeus harrisii tridentatus, were studied during six months (July to December, 2005) in Noor coast of the South Caspian Sea (the Noor coast). From the 175 collected specimens, 47.4% were males and 52.6% were females. Comparison of the carapace width, carapace length, chela length and height and wet weight showed the males significantly were larger than females (P<0.05). Maximum and minimum carapace width in males and females were 5.4-15 and 4-14 mm, respectively. Significant relationship (P<0.05) was found between carapace length and other characteristics. In addition, the results of this study showed that the size of this species in Caspian Sea is smaller than the other areas.

The biomass fluctuation of the green seaweeds in the intertidal zone of Chabahar was estimated from. April 2005 to March 2006 (one year) Sampling was performed monthly using 50´50 cm quaderate. The samples were identified to species level and the biomass of each species was measured. Totally 5 genera of green seaweeds, including: Ulva (one species), Caulerpa (3 Species), Chaetomorpha (one species), Enteromorpha (one species) and Halimeda (one species) were identified. Total biomasses of these seaweeds were 718760 kg. and monthly average were 59896 kg. The maximum biomass of 109260 kg (%15.2) was obtained in Aug. and minimum biomass of 5708 kg. (%0.8) was obtained in Dec. Maximum biomass belonged to Ulva fasciata (%70.7) and minimum biomass belonged to Halimeda tuna (%0.2).