Population dynamics of pearl oyster Pinctada radiata west of Lavan Island of the Persian Gulf, Iran

Investigation on pearl oyster, Pinctada radiata growth and mortality parameters was carried out from September 2001 to October 2002 in west of Lavan Island using scuba diving method. Hinge length (HL) and dorsoventral measurement (DVM) relationship was significantly (r ^ (2) =0.98) linear. Weight and dorsoventral measurement relationship was shown to be W=0.0004 L ^ (2.812) (r ^ (2) =0.98). Asymptotic length (L infinity) and growth rate (K) were estimated at 98 (mm) and 0.96 y ^ (-1) respectively. More than 70 percent of the individuals were matured in April 2001. Mortality parameters including natural mortality (M), total mortality (Z) and fishery mortality (F) were estimated to be 1.21y ^ (-1), 1.68y ^ (-1) and 0.66y ^ (-1) respectively. Exploitation rate was estimated to be 0.27 in this survey

Effects of water temperature on filtration rate of micro-algae Isochrysis affines galbana by black lip pearl oyster spat (Pinctada margaritifera)

This study was conducted to compare the effects of varying water temperatures on filtration rate of micro-algae Isochrysis affines galbana by Pinctada margaritfera spat on microalgae. To determine the optimum temperature and maximum filtration rate, 10 pearl oyster. margaritfera spats with mean total and total hinge length 32.67 ±2.76 and 31.57 ±2.90 respectively were stocked in 70 liter rectangular glass tanks supplied with filtered seawater. The spats were exposed to seven treatments of temperature including 18.5 ±0.21°C, 20.5 ±0.21°C, 23 ±0.1°C, 24.5 ±0.31°C, 26.5 ±0.21°C, 27.5 ±0.15°C and 28.5 ±0.21°C with 3 replicates. The results of filtration on I. affines galbana showed that the maximum filtration of spats on microalgae cells and water volume were 181,324,595 cells and 3626 ml per hour and 635,031,212 cells and 12700 ml per two hours in 27.5 ±0.15°C, respectively. The minimum filtration of microalgae cells and water volume were 5,224,028 and 104ml per hour and 65,874,413 cells and 1317 ml per two hours in 18.50 ±021C, respectively. The results of this study demonstrated that the optimum temperature for maximum feeding of spats on I. affines galbana is 27.5 ±0.15°C

Life cycle of pharaoh cuttlefish (Sepia pharaonis) under laboratory condition

Pharaoh Cuttlefish (Sepia pharaonis) is commercially important and native cephalopods in the Persian Gulf and Oman Sea. In 2013, a total of 150 eggs of Pharaoh Cuttlefish were collected from 20 m depth in about 6 miles south of Lengeh Port and transferred to the laboratory of Mollusks Research Station in Bandar-e Lengeh. Eggs were incubated in temperature of 27.5±0.5 0C (mean ± SD) and salinity of about 37-38 ppt. After about 15±3 days (mean ± SD), eggs were hatched and the mean (±SD) of mantle length and wet weight of new hatched juveniles were 6.1±0.3 mm and 0.15±.04 g, respectively. In the first month, Artemia, Mysid and PL of L. vannamei shrimps were fed to juveniles and in second month it shifted to fish slices. After 30 days, average (±SD) mantle length and wet weight reached to 18.6±0.6 mm and 1.67±0.14 g, respectively. At the age of 60 days they reached to average (±SD) length of 32.3±4.2 mm and average (±SD) weight of 8.00±3.72 g. At the age of 120 days they reached to average (±SD) length of 74.5±11.3 mm and average (±SD) weight of 55.74±13.81 g. The sex was identified on the day of 150, and mate selecting occurred on 180th day, mating and spawning were occurred in days 208 and 210 of rearing period, respectively. Each female laid average (±SD) 185±30 eggs; and average (±SD) life spans for female and male were 212±7 and 218±20 days, respectively. Males were bigger than females and the biggest male reached to 157.9 mm in length and 367.10 g in weight. The biggest female reached to 105.1 mm in length and 227.18 g in weight. Results showed that Pharaoh Cuttlefish could easily be cultured under laboratory condition with possibility of rearing to the next generation after spawning

Density index and length scale of Pearl Oyster Pinctada radiata in two habitats around Hendorabi Island (Iran, the Persian Gulf)

As pearling has been banned in Iran since 2006, stocks of pearl oysters has not been investigated during these years; therefore, condition of natural habitats for Pinctada radiata in its old habitats was surveyed in present research. Shallow waters around Hendorabi Island were searched with diving and two habitats namely “Sooleh” and “Sahel-e-sheni”, were considered for study. The pearl oysters had most distribution in these habitats in depth ranges of 7 to 12 m and 8 to 11 m, respectively. Total stock in Sooleh and Sahel-e-sheni was surveyed near 35700 and 12563 Pinctada radiata, respectively, of which 22% and 67% were catchable, respectively. Catch Per Unit of Area (CPUA) in Sooleh and Sahel-e-sheni habitats was estimated equal to 0.3 N/m2 in both habitats, and Catch Per Unit of Effort (CPUE) in these habitats was calculated equal to 59.5 N/hr and 50.3 N/hr, respectively. Results of this study demonstrated that area, stocks and CPUA for studied habitats were less than previous years. Despite of interdict of pearling in this region since 7 years ago, stock revival has done slowly

Study of existing biological communities in Hormuzgan province waters (Persian Gulf) for installation of artificial reefs

To determine the suitable locations for installation of artificial reefs we studied Persian Gulf waters (Hormuzgan province) from December 2006 to March 2007 seasonally. The area was stratified to 10 transects and each transect was divided to three layers and used random sampling method. Habitats of fauna and flora including: Communities of corals, seaweeds, sea cucumbers and sea grasses, and sedimentation depth using SCUBA diving method were studied in each transect and layer. Sea grass communities existed in some places with below 10m depth of Bandar Mesan, Bandar Kang, Kish Island and Bandar Chirooyeh transects. Also, seaweed habitats were seen in Bandar Mesan and some areas in Bandar Lengeh and Kish Island in 10-20m depth transect. The study of coral and sea cucumber communities indicated presence of Acropora sp. habitats in Bahman jetty, Bandar Mesan and Bandar Bostaneh transects , and Porites sp. habitats in Hengam island transect, Holothuria sp. habitats in Bandar masen and Bandar Lengeh transects and Stichopus sp. habitat in Hengam Island transect. All these species were found in shallow waters bellow 10 meters depth and showed a patchy distribution. Sedimentation depth results showed a statistically significant difference between layer <10m in Bandar Salakh and the same layers in other transects, also between layer 10-20m and 20-30m in other transects. Based on the sedimentation depth and habitats studies, we recommend layer 10-20m in Bandar Lengeh area and Bandar Lengeh to Hendurabi Island area as suitable for artificial reefs installation

Propagation and rearing larvae of black lip pearl oyster Pinctada margaritifera until spat stage

The black lip pearl oyster Pinctada margaritifer is one of the three valuable species of pearl oyster for the cultured pearl industry of the world. Due to its high economical value, endangered species status in Persian Gulf, its historical and social importance, and the technical feasibility to produce pearl oysters seeds in hatchery, Persian Gulf Shellfish Research Center in northern part of Persian Gulf, Iran developed the spat production of this important species for the first time. Ten pairs of matured P. margaritifera broodstocks collected from the pearl oysters beds in Lavan Island, Persian Gulf during Jun-July 2004, were transferred to the hatchery at the Persian Gulf Shellfish Research Center. All the broodstocks were thoroughly brushed free of fouling organisms and washed with freshwater. The oysters subjected to thermal stimulation (temperature elevated from 20 °C to 30 °C). Around 70% of oysters spawned approximately after an hour. Fertilization was normal ranging between 97-98% and early larval development was viable. Six one-tone fiberglass tanks holding 1μ filtered and UV sterilized seawater with gentle aeration were used for culturing the larvae. Pure culture of three micro algae, Isochrysis aff galbana ,Chaetoceros calcitrans and Chaetoceros mulleri were used as diets. Feeding started with I. galbana and a combination of I. galbana and C. calcitrans from day 4 of rearing period. The initial larval density was 50 larvae/mL at D-Shape larval stage and reduced to 1 laravae/mL at later stages. The larvae reached to the D-Shape stage between 20-24 hours, Umbo stage on day 6-12, Eye-spot on day 17-21and Pediveliger and Plantigarad on day 22-30. Oyster Spats were settled on collectors after 32 days of rearing period. Survival rate was 70% at D-Shape stage, 60% for Umbo stage, 50% for Eye-spot and 30% for Spat. Total produced spat 123500 in two years and realized and transferred 23500 spat to sea

A study on distribution and biomass estimination of seaweeds in coastal and its islands

Distribution and biomass of seaweeds in the Persian Gulf and its islands were assessed monthly during low tide from July 2001 to August 2003. Ten stations were defined in the study area and random spots along a transect vertical to the coastline were selected to carry out the sampling. Six stations were located in the coastal waters and four others were close to the islands. Samples were taken in quadrats 0.25 square meter in size (0.5mx0.5m). As a result, 77 species belonging to 4 division of seaweeds were identified. Rhodophyta was represented by 38 species, Chlorophyta had 21 species followed by 17 species of Phaeophyta and only I species of Cyanophyta. The highest and lowest seaweed diversity was seen around Larak Island and Michael station with 74 and 31 species respectively. Although some species such as Gracilaria corticata, Gelidiella acerosa, Laurencia snyderia, Colpomenia sinousa, Padina australis and Diciyosphaeria covernosa were abundant in all stations during the study, some species were absent from some stations. Thrbinaria conoiedes was only seen in Larak island, Spatoglassum variable and Steochospermum marginatum were present only in Larak and Qeshem islands, Codium papilatum and Ulva spp. were spotted only in Larak and Hormoz islands, and Sargassum ilicifolium was detected only in Bandar Lengeh, Shiyo, Larak and Qeshem islands. The maximum and minimum algal biomass (wet weight) was recorded in Bandar Lengeh with 1.058gram^2 and Qeshem island with 391gram'2 and there was significant difference between the two stations (P<0.05). Also the maximum algal biomass was recorded in summer (1466gr.m^2) in Tahoneh-Gorzeh and the minimum biomass (130gram^2) in Qeshem islands. The highest biomass was recorded for the brown algae division (824gram^2) in Bandar Lengeh and the minimum biomass was seen for the green algae division (26gram^2) in Hormoz. and Qeshm islands. The maximum biomass was 755gram in summer for red algae, 1160gram^-2 in Spring for brown algae and 519gram^2 in Summer for green algae

Monitoring of commercial marine stocks around Hormuzgan (bandar-e-Lengeh) artificial reefs

Over-fishing of marine resources has endangered many commercial fish species in the world; with aquaculture development, setting up artificial reef systems is an important way for marine stocks and fishing enhancement. The present study was designed to monitor fish abundance and species changes around a small and newly established artificial reef system in Moloo area at Bandar-e-Lengeh during two years after installation (Sep. 2005 to Sep. 2007). The artificial reef includes three types of concrete structures arranged in a seven by three grid. Each cross point considered as a sampling station and two other stations selected from two sides of the system as control stations. Based on obtained results CPUE (P = 0.00001), frequency (P = 0.001) and species diversity of captured fishes (P = 0.024) showed significant differences between three types of sampling traps. With type of structures, The CPUE and frequency of fishes in transect 7(mixed structures) showed the significant differences with other six transects (p= 0.001, P = 0.009). No diversity relationships were seen between transects (p= 0.100). In this study there were no significant differences between depths. Although the means of CPUE between seasons were different, but the ANOVA test could not show the significant differences because of the differention between variances. The T-Test showed no significant differences between the numbers per trap per day dominant species (Epinephelus coioides, Plectorhinchus shotaf, Diagrama pictum, Siganus javus) in different seasons. Movie prepared from artificial reefs showed diversity of fish were more than that of fishing by trap. Although fishes increased but there was no enough causes evidences for product in artificial reefs. Therefore, the study need to continue in this area

Nutritional requirements to increase the survival rate of black-lip pearl oyster, Pinctada margaritifera from D-shape to spate stage

Black lip pearl oyster (pinctada magaritifera) is one of the most important species of Pearl maker in the world. Its reserves in the Persian Gulf waters is facing to a variety of causes, especially oil pollution from Persian Gulf war that cause genetic changes in pearl oyster. 65 broodstocks black lip pearl oyster mature with average length of the dorsal ventral (15 ± 2cm DVM) were collected from its typical natural Lavan Island in the months of June and July 2007 and were transferred to the research station and then were washed in cold rooms (20 ° C). The gonad indices were determined by microscope based on the gametogenez steps. After 2 days from collection time, the broodstocks were exposed to thermal shock in order of spawning stimulation. For the analysis of biochemical compounds, microalgae were sampled at logarithmic phase stage with three replications. Firstly, the samples were concentrated by centrifuges (3500g, 20 min). After washing with ammonium formate solution 0.5 molar, the samples were again centrifuged at 3500 g for 15 min. After spawning, D shape larvae form and then the larva ambo feeded from different micro-algae and lipid and the amount of growth and survival rates were studied. D shape larvae with 3 larvae per ml density and dorsal- abdominal length of 78.9 ± 0.7 μm were cultured in 5 liter Erlenmeyer flask containing 2 liters water. Whereas, samples at umbo stage with average dorsal-ventral length of 133 ± 3.1 μm were cultured in 15 liters plastic containers at 27- 29 ° C and salinity of 34 to 35 parts per thousand. The studied microalgae were Isochrysis aff galbana, Chaetoceros calcitrans and c.muelleri. The results of biochemical compounds showed that protein is the most component of all species with a maximum amount of 527.5 ± 2.1 mg g^-1 in T. Iso microalgae. Also, T. Iso has a maximum amount of lipids, following by seek c. muelleri and c. calcitrans, respectively. Test results showed that feeding of larvae black lip pearl oyster in stage D shape with microalgae T. Iso alone has more growth rate than double or triple mixtures. However, diatoms have a high nutritional value for larval mussels in umbo state, and they are accounted as important components in a double and triple mixture of microalgae diet. The size of the larval D shape after 10 days showed a difference among treatments. The cultured larves that feeded from T Iso reached to maximum length of 111.4 ± 10 μm and the maximum survival rate of 57.7% was related to larves that feeded by fresh microalgae T. Iso. D.V.M for microalgae with microalgae or lipid nutrition showed no significant difference

Feasibility study on development of artificial reefs in the Persian Gulf (Hormuzgan province)

Persian Gulf waters (areas of Hormuzgan province) in order to determine the best location for installation of Artificial reefs were studied seasonally from December 2006 to March 2007. Distribution of fauna and flora and estimation of deposit depth by SCUBA diving method, density and frequency of macrobenthose communities, frequency of ichthyoplankton communities, determination of organic carbon (OC) and Grain size and measurement of water physical factors including salinity, saturation oxygen, dissolved oxygen, temperature, chlorophyll a, in transect and subtransect was studied for recognizing the best placement to installation of artificial reefs. All areas of Shipping, military areas, around of Islands, natural habitats and entrance to jetty were introduced for excluding areas. South of Qeshm Island (transects of Bahman jetty, Bandar Masen and Bandar Salakh) are catching area for small pelagic (sardine and anchovy fishes), therefore in these areas installation of artificial reefs have confined with this restriction. Also entrance to Bahman jetty, sea plant habitats (sea grass and algae) in transects of Bahman jetty and Bandar Masen were considered as restricted areas. In this area, suitable areas for installation of artificial reefs was determined based on distribution of Ichthyoplankton societies for every transect, for macrobenthose enrichment Bahman jetty transect was calculated middle, but transects of Bandar Masen, Hengam island and Bandar Salakh was done good indicator. The deposition depth in transects of Bandar Masen and Hengam island was determined as good factor but this index was known as average factor for transects of Bahman jetty and Bandar Masen. Also, two another indicators, primary production and bottom sturdiness, were calculated as middle factor for Bahman jetty transect, but these indicators were known as good factors for other transects in this area (Bandar Masen, Hengam island and Bandar Salakh). The results of these indicators in transects of Bandar Kong and Bandar Bostaneh in Bandar Lengeh area was indicated that T. O. C and bottom sturdiness indices had no significant difference (p>0. 05) and the whole of these transects had average priority. Bottom sturdiness, primary productions and macrobenthose communities indices had difference in Bandar Lengeh area (p<0. 05) and these indices had average priority in Bandar Kong transect and had good priority in transects of Bandar Bostaneh and Bandar Hasineh. Ichthyoplankton community had average priority for Bandar Bostaneh transect, and had good priority for transects of Bandar Kong and Bandar Hasineh. The good priority has obtained for transects of Bandar Charak, Bandar Gorzeh and Bandar Chiroeyah. Also Macrobenthose community, primary production, water physical factors and bottom sturdiness were known as good, good, average and weakness priority respectively for transects of Bandar Charak, Bandar Gorzeh, but primary production, bottom sturdiness, water physical factors and macrobenthose community were resulted as average, good, good and average priority respectively for Bandar Chiroeyah transect . T.O.C index was determined as average priority for transects of Bandar Gorzeh and Bandar Chiroeyah and good priority for Bandar Charak transect. Finally, excluded areas maps, suitability areas maps and feasibility areas maps were drawn by Arc GIS software. In this survey, layers between 10 to 20 meters depth were recognized as the best position for installation of artificial reefs