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  • 1
    Publication Date: 2018-08-03
    Description: In order to culture the G. corticata for further agar extraction, during one year study (2001), 3 treatments with 3 different densities of 500, 1000 and 2000 g/m^2 and 3 replicates were cultured in fiberglass tanks. During the culture period the parameters of temperature, pH and salinity were measured and 30-40 percent of water was exchanged once every two days. The aeration activity was constantly done and also 0.5g urea added into the water after exchanging the water. The biometric measurement of algae was carried out every week and ultimately end of the period culture, the daily growth and net production (wet weight) was calculated in proportion to g/m2. Also, amount of extracted agar (dry weight) estimated seasonally. In winter, the daily growth (%), net production and agar extracted (%) were estimated 1.46±0.11, 11.5±3.57 and 17.5%, in which these figures for three other seasons of spring, summer and autumn were: 3.74±0.31, 38.3±5.4, 19.3 and 1.5±0.28, 12.43±3.3, 14% and 3.11±0.04, 26.9±0.61 and 15%, respectively. Some epiphytes and grazers were recognized in algae cultivation tanks such as Navicula, Nitzschia, Oscillatoria, Peridinium, Chaetoceros, Enteromorpha, Ulva, and Isopoda, Nemertine and Nereis. Two seasons of spring and autumn showed the best daily growth and net production, and also the 500 g/m^2 treatment was recognized the best culture treatment.
    Keywords: Aquaculture
    Repository Name: Aquatic Commons
    Type: Article , PeerReviewed
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  • 2
    Publication Date: 2018-10-13
    Description: Shrimp is one of the most important aquatic animals,that have decreased their stocks in Hormozgan province, especially the eastern province . Evalution of food interaction in shrimp habitats (Estuaries of Tyab, Yek shabeh, Laft and Khouran) was studied with Ecopaht with Ecosim software (ver. 6.5) in Hormuzgan province. After entering the input components (Biomass,P/B and Q/B), model was balanced and outputs were extracted. Results of trophic levels, was close to previous research in these areas for all species in estuaries. Maximum of ecotrophic efficiency was belonged to phytoplankton and other preys that were observed in predator stomachs. Biological future of food web estimated to be threatened based on omnivore index of planktonivore groups. Maximum food competition between the four food models was estimated in detritivores communities in Laft estuary, that may be related to the low density of mangrove in this region. Khamir estuary ecosystem could be more stable, because each impacting group had its own separate ecological niche and special predation territory. key indices in each of four food models were related to phytoplankton communities, this key role has been demonstrated much better in Yek Shovy estuary than others. Future of commercial shrimp stocks will be expected to be in better condition in Khoran estuary compared to other three ones, due to selection of separate ecological niche by predators and High biomass of detritus in this estuary.
    Keywords: Biology ; Ecology
    Repository Name: Aquatic Commons
    Type: Monograph or Serial Issue , NonPeerReviewed
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  • 3
    Publication Date: 2018-10-13
    Description: The most important habitats of mudskippers are muddy areas in tidal zone of tropical mangrove forests. Mudskippers are related to Oxudercinae subfamily of Gobiid fishes. Three most distributed species of Hormozgan mudskippers were Periophthalmus waltoni, Boleophthalmus dussumieri and Scartelaos tenuis. These fishes can be considered as euryhaline and eurythermal aquatic species, because they can tolerate a wide range of salinity and temperature. A research was done since september 2008 to september 2009 in two important mangrove regions of Hormuzgan (Tyab and Khamir) to determine some ecological characteristics of inhabited mudskipper species. Results showed that nitrate levels are significantly different between tidal lines and seasons (P〈0.05). Maximum nitrite concentrations were recorded 53.2 and 92.5 µg/l in Khamir and Tyab respectively. The annual correlation matrix showed that a positive correlation between phosphate concentration and nitrite and silicate (P〈0.05). Silicate concentration was very high, because of too low density of diatoms and radiolarians. Some species of diatoms, dinoflagellates, cyanobacteria and larvae of crustacea and echinoderms were observed with different density and diversity. Sediment composition of the studied areas were categorized in three classes (clay, sand and clay - sand). Polychaetes formed dominant group of benthic fauna in Tyab and Khamir areas. High density of capitellid worms was possibly related to some environmntal stress caused by activity of fishing and cargo vessels. It was not observed significant difference between fishes length in two areas (P〈0.05); Mean lengths of P. waltoni, B. dussumieri and S. tenuis were calculated 9.85, 14.7 and 11.5 cm respectively. Spawning period of each three species in both areas were obtained from late winter to late spring based on gonadosomatic index values. Male to female sex ratio of P. waltoni, B. dussumieri and S. tenuis were calculated 1:0.45, 1:0.41and 1:0.74 respectively. Absolute fecundity of P. waltoni, B. dussumieri and S. tenuis were estimated 3558 ± 2202, 3952 ± 1030 and 6742 ± 1939 respectively. P. waltoni feeds mainly on fiddler crab, S. tenuis uses crustaceans and gastropods and B. dussumieri has a vegetarian diet.
    Keywords: Ecology
    Repository Name: Aquatic Commons
    Type: Monograph or Serial Issue , NonPeerReviewed
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  • 4
    Publication Date: 2018-07-15
    Description: 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.
    Keywords: Biology
    Repository Name: Aquatic Commons
    Type: Article , PeerReviewed
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