Hadi Dehghan; Mir Masoud Sajjadi; Paria Parto; Hamid Rajaian; Jafar Jalaei
Volume 12, Issue 3 , September 2014, , Pages 33-41
Abstract
Rays are common elasmobranches in the northern waters of Persian Gulf and Oman Sea that may have one or more mineralized serrated stingers on the whip-like tail. The stingers are covered by epidermal cells among which some can produce venom. When these animals are dorsally touched, the stinger may be ...
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Rays are common elasmobranches in the northern waters of Persian Gulf and Oman Sea that may have one or more mineralized serrated stingers on the whip-like tail. The stingers are covered by epidermal cells among which some can produce venom. When these animals are dorsally touched, the stinger may be introduced into the aggressor by a whip reflex mechanism, causing severe mechanical injuries and inoculating the venom. A comparative morphological characterization of the stinger epidermal tissue of different ray species in the northern part of Persian Gulf and Oman Sea was carried out in this study. EDTA was used for decalcification of stings and conventional histological processes were subsequently employed. The results indicated that structure of dermis and epidermis layers of stings in all species are similar to those of corresponding layers in other parts of fish’s body. The results of the present study have also shown that all three examined species, had venom secretory cells. Distribution of venom secretory cells varies in each species; in Dasyatis bennetti and Himantura walga species, these cells presented in all covered epithelium of stings and in Himantura gerrardi, were in the ventral, ventro-lateral and dorso-lateral of the spine. These differences among the stingers of various species may explain the envenomation severity in these species.
Esmaeil Karami; Mirmasoud Sajjadi; Mohammad Amin Soltani; Abdolrasoul Daryaei
Volume 12, Issue 1 , April 2013, , Pages 80-90
Abstract
This study was conducted to investigate the effect of initial stocking density of red algae Gracilaropsis persica and Gracilariacorticata on the growth and biomass production of these species. Three stocking densities of 50 gm-1, 125 gm-1 and 200 gm-1 were used and algae cultivated in Persian Gulf (Bandar ...
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This study was conducted to investigate the effect of initial stocking density of red algae Gracilaropsis persica and Gracilariacorticata on the growth and biomass production of these species. Three stocking densities of 50 gm-1, 125 gm-1 and 200 gm-1 were used and algae cultivated in Persian Gulf (Bandar Abbas) in winter for 45 days. Algae collected from natural environment and cultivated on poly ethylene rope in the sea.Relative growth rate (RGR) and total biomass were measured fortnightly. Temperature, salinity, pH and nutrients (nitrate, nitrite and phosphate) were measured during the trial. The result of the present study showed that there were significant differences in growth rate between different treatments in both species (P<0.05). Algae that cultivated with 50 gm-1 initial stocking density had the highest relative growth rate in both species. At the end of 45-day trial, total biomass was the highest in 200 gm-1 treatment (P<0.05). Furthermore, the present study showed that the growth rate of Gracilariopsis persica was higher than Gracilariacorticata. The results of the present study showed that stocking density is able to affect the growth of red algae Gracilariopsis persica and Gracilariacorticata and Gracilariopsis persica have higher growth rate and better potential of commercial culture in the Persian Gulf compared to Gracilariacorticata.