اثرات متقابل شوری و تراکم بر شاخص های بیوشیمیایی سرم ماهی باس دریایی (lates calcalifer)

تعیین شوری بهینه برای پروش ماهیان دریایی از اهمیت بسیاری برخوردار است. همچنین تراکم به عنوان یکی از مهمترین عوامل تاثیر گذار بر رشد و ایمنی آبزاین پرورشی همیشه مورد توجه قرار گرفته است. مطالعه حاضر ﺑﻪ ﻣﻨﻈﻮر ﺗﻌﻴﻴﻦ شوری و ﺗﺮاﻛﻢ مناسب ذﺧﻴﺮهﺳﺎزى برای ماهی باس دریایی آسیایی در ﺷﺮاﻳﻂ ﭘﺮورﺷﻲ اﻧﺠﺎم شد. هدف اصلی از این تحقیق، بررسی اثرات متقابل تراکم و شوری بر پارامترهای بیوشیمیایی ماهی باس دریایی آسیایی است. به منظور انجام این آزمایش، تعداد 450 قطعه بچه ماهی باس‌دریایی (lates calcalifer) با میانگین وزن اولیه 5/4±30 گرم، بطور تصادفی انتخاب و در27 مخزن فایبرگلاس (هر تیمار در 3 تکرار) تقسیم شدند و به مدت دو ماه با جیره‌های غذایی تجاری، تغذیه شدند. بطور کلی در این پژوهش 9 تیمار آزمایشی شامل 3 سطح شوری (ppt 10، 20 و 30) و 3 سطح تراکم (1، 2 و 3 کیلوگرم بر متر مکعب) به صورت متقابل مورد ارزیابی قرار گرفتند. ماهیان در طول دوره آزمایش، تا حد سیری به صورت دستی تغذیه شدند. جهت بررسی وضعیت فیزیولوژیک ماهیان پس از دو ماه تغذیه، از ماهیان خون‌گیری و جداسازی سرم به عمل آمد. پارامترهای بیوشیمیایی مورد مطالعه شامل کلسترول، تری گلیسرید، گلوکز، پروتئین تام، آلبومین، فسفر، منیزیم، کلسیم و ldl و hdl، به روش آنزیمی-فتومتریک مورد سنجش قرار گرفتند. بر اساس نتایج به بدست آمده در این تحقیق، سطوح مختلف شوری دارای اثرات معنی داری بر میزان تری گلیسرید و گلوکز سرم بود  (p<0/05). میزان تراکم فقط در شاخص منیزیم سرم تاثیر معنی دار داشت (p<0/05) و در سایر شاخص ها تاثیر معنی داری مشاهده نگردید (p<0/05) بر اساس آنالیز آماری صورت گرفته، اثر متقابل شوری و تراکم بر میزان آلبومین دارای اثر معنی دار بوده است به طوری که در شوری متوسط و تراکم متوسط کمترین میزان آلبومین سرم مشاهده گردید. همچنین شوری و تراکم دارای اثرات متقابل معنی دار بر میزان گلوکز سرم نیز بودند (p<0/05). با توجه به نتایج به دست آمده از مطالعه حاضر می توان گفت که ماهی سی باس آسیایی می تواند گزینه مناسبی برای پرورش در آب های لب شور (شوری 20 گرم بر لیتر ) و تراکم متوسط (2 کیلوگرم در متر مکعب) باشد.

interaction effects of salinity and density on serum biochemical indices of asian sea bass (lates calcalifer)

abstractthe present study was conducted to determine the appropriate stocking density and salinity for asian sea bass (lates calcalifer) in rearing conditions. the main purpose of this research is to investigate the mutual effects of density and salinity on the biochemical parameters of asian sea bass. to perform this experiment, 450 sea bass fingerlings with an average initial weight of 30±5.4 grams were randomly selected and divided into 27 fiberglass tanks (each treatment in 3 replicates) and fed with diets for two months. they were fed commercial food. in general, in this research, 9 experimental treatments including 3 salinity levels (10, 20, and 30 ppt) and 3 density levels (1, 2, and 3 kg/m3) were mutually evaluated. during the experimental period, the fish were fed manually until satiety. to investigate the physiological condition of the fish after two months of feeding, blood was taken from the fish's caudal vein and serum was separated. the studied biochemical parameters including cholesterol, triglyceride, glucose, total protein, albumin, phosphorus, magnesium, calcium, ldl, and hdl were measured by enzyme-photometric method. based on the results obtained in this research, different levels of salinity had significant effects on serum triglyceride and glucose levels (p<0.05). the density had a significant effect only on the serum magnesium index (p<0.05) and no significant effect was observed on other indices (p<0.05). based on the statistical analysis, the interaction effect of salinity and density on the amount of albumin has a significant effect, so the lowest amount of serum albumin was observed in medium salinity and medium density. also, salinity and density had significant interaction effects on serum glucose (p<0.05). according to the results obtained from the present study, it can be said that asian seabass can be a suitable option for culture in brackish waters (salinity 20 g/l) and medium density (2 kg/m3). introduction:it seems that each fish species has an optimal water salinity specified for the growth of that species. salinity along with other parameters such as temperature, feed consumption, sex, and growth stage may also affect the growth performance (boeuf and payan, 2001). it has been proven that the digestive capacity of fish can change due to changes in the amount of drinking water in different densities and salinities of water, which may affect the activity of digestive enzymes, the salinity content, the composition of ions, and the ph of the intestine. (gifard-mena et al., 2006). it seems that there has been no study on the mutual effects of density and salinity on asian sea bass (lates calcarifer). this study was done to determine the suitable stocking density and salinity for asian sea bass in farm conditions and the main part of this research is to investigate the mutual effects of density and salinity on the biochemical parameters of asian sea bass. materials and methodsto perform this experiment, 450 sea bass fingerlings with an average initial weight of 30±5.4 grams were randomly selected and divided into 27 fiberglass tanks (each treatment in 3 replicates) and fed with diets for two months. they were fed commercial food. in general, in this research, 9 experimental treatments including 3 salinity levels (10, 20, and 30 ppt) and 3 density levels (1, 2, and 3 kg/m3) were mutually evaluated. during the experimental period, the fish were fed manually until satiety. in order to investigate the physiological condition of the fish after two months of feeding, blood was taken from the fish's caudal vein and serum was separated. the studied biochemical parameters including cholesterol, triglyceride, glucose, total protein, albumin, phosphorus, magnesium, calcium, ldl, and hdl were measured by enzyme-photometric method. resultsbased on the results obtained in this research, different levels of salinity had significant effects on serum triglyceride and glucose levels (p<0.05). the density had a significant effect only on the serum magnesium index (p<0.05) and no significant effect was observed on other indices (p<0.05). based on the statistical analysis, the interaction effect of salinity and density on the amount of albumin has a significant effect, so the lowest amount of serum albumin was observed in medium salinity and medium density. also, salinity and density had significant interaction effects on serum glucose (p<0.05). conclusionbecause aquaculture is often related to high density, the production and culture systems should consider the quality of the product and health, which depends on proper care and culture methods (irwin et al., 1999). it has been proven that changing the culture density is a source of stress for fish. stocking density directly depends on the calmness of the fish culture environment and plays a role as a determining factor in the amount of fish production and economic efficiency. optimum density improves the quality of the rearing environment and growth rate (braun et al., 2010; van de nieuwegiessen et al., 2008). euryhaline fishes are relatively able to keep the ratio of ionic compounds and osmolarity of internal body fluids constant (when exposed to different salinities), this action is done through a series of ionic processes and osmotic adjustments that require energy (lisboa et al., 2015; nordlie, 2009).in general, based on the results of this research, the lowest amount of changes in serum parameters was observed in mean salinity (20 ppt) and densities of 1 and 2 kg per cubic meter. even though this species is considered a euryhaline species, low salinities near fresh water lead to increased stress and increased metabolism, which can further cause negative effects on the growth rate and also the fish's immune system. further studies on immune system variables and growth and nutrition indicators can provide better operational results for the use of aquaculture farmers while confirming the results of this research. based on the results, it can be said that this species can tolerate changes in the range of seawater to brackish water within 60 days and successfully adapts to fresh water, so it can be a suitable option for culture in brackish water (20 ppt of salinity) and mean density (2 kg per cubic meter).references:boeuf, g. and payan, p., 2001. how should salinity influence fish growth? comparative biochemistry and physiology, part c, 130: 411–423. doi: 10.1016/s1532-0456(01)00268-xbraun, n., lima de lima, r., baldisserotto, b. and dafre, a.l., pires de oliveira nuñer, a., 2010. growth, biochemical and physiological responses of salminus brasiliensis with different stocking densities and handling. aquaculture, 301: 22–30. doi: 10.1016/j.aquaculture.2010.01.022giffard-mena, i., charmantier, g., grousset, e., aujoulat, f., castille, r., 2006. digestive tract ontogeny of dicentrarchus labrax: implication in osmoregulation. development, growth and differentiation, 48, 139–151. doi: 10.1111/j.1440-169x.2006.00852.xirwin, s., o'halloran, j., fitzgerald, r.d., 1999. stocking density, and growth variation in juvenile turbot, scophthalmus maximus (rafinesque). aquaculture, 178: 77–88.lisboa, v., barcarolli, i.f., sampaio, l.a., bianchini, a., 2015. effect of salinity on survival, growth and biochemical parameters in juvenile lebranch mullet mugil liza (perciformes: mugilidae). neotropical ichthyology, 13: 447–452. doi: 10.1590/1982-0224-20140122nordlie, f.g., 2009. environmental influences on regulation of blood plasma/serum components in teleost fishes: a review. review in fish biology, 19: 481–564. doi: 10.1007/s11160-009-9131-4van de nieuwegiessen, p., boerlage, a., verreth, j. and schrama, j., 2008. assessing the effects of a chronic stressor, stocking density, on welfare indicators of juvenile african catfish, clarias gariepinus burchell. applied animal behaviour science, 115: 233–243. doi: 10.1016/j.applanim.2008.05.008