تعيين دانه بندي، مواد آلي كل و جوامع باكتريهاي بيهوازي اختياري رسوب تحت تاثير پرورش قزل آلاي رنگين كمان (Oncorhynchus mykiss) در قفس شناور در منطقه عباس آباد، حوضه جنوبي درياي خزر

Determination of sediment grading, Total Organic Matter and facultative anaerobic bacteria affected by rainbow trout culture in floating cage in the Abbas Abad area, southern basin of the Caspian Sea

اين تحقيق با هدف تعيين دانهبندي بستر، مواد آلي كل و جوامع باكتريهاي بيهوازي اختياري رسوب تحت تأثير فعاليت پرورش قزلآلاي رنگينكمان در قفس در منطقه عباسآباد، حوضه جنوبي درياي خزر طراحي گرديد. بدين منظور نمونهي رسوب از فواصل 5، 50، 100 و 1000 متري از قفسهاي پرورش ماهي طي 4 دوره شامل ماه دي (قبل از پرورش) و اسفند 1393 و ماه ارديبهشت (دوره پرورش) و ماه مرداد 1394 (بعد از دوره پرورش) جمعآوري شدند. تعيين دانه بندي بستر نشان داد كه جنس بستر بيشتر از دانه هاي سيلت-رس (91/7%) و ماسه خيلي ريز (6/44%) تشكيل شده بود و ساختار آن تحت تأثير فعاليت پرورش ماهي در قفس قرار نگرفت. ميزان مواد آلي كل رسوب فقط در دورههاي مختلف نمونهبرداري تفاوت معنيدار داشت (0/05>P) بهطوريكه، بيشترين ميزان آن همزمان با دورهي پرورش مشاهده گرديد در حاليكه، اثر فاصله از مركز قفس معني‌دار نبود (0/05P)، اما بين ايستگاههاي مختلف تفاوت معنيدار مشاهده نگرديد (0/05

This study was designed to determine the sediment structure, Total Organic Matter (TOM) and facultative anaerobic bacteria communities of sediment affected by cage culture of rainbow trout in the coastal waters of Abbas Abad area (southern basin of the Caspian Sea). For this purpose, sediment samples were collected at distance of 5, 50, 100 and 1000 m from the cages in December 2014 (before the culture period), March and April (production period) and August 2015 (after the culture period). Determination of sediment grading showed that its structure was composed of silt-clay (91.7%) and very fine sand (6.44%) and the sediment structure was not affected by the cage culture. The Total Organic Matter was significantly different only between the sampling periods (P<0.05) so that the highest amount of Total Organic Matter (TOM) was observed during the production period whereas, it was not affected by the distance from the cages (P<0.05). It seems that the rainbow trout cage culture in the Abbas Abad region no remarkable effect on the factors studied in the vicinity of small scale fish cages due to the short duration of cage culture and strong water currents, so that observed changes were more associated with seasonal fluctuant.