بررسي ساختار جمعيت بزرگ بي مهرگان كفزي در سواحل جنوبي درياي خزر بمنظور استقرار قفس هاي پرورش ماهي

Structure of macrobenthic invertebrate population in the southern coast of Caspian Sea for fish cage culture establishmen

اين پژوهش در راستاي برنامه استقرار قفس هاي پرورش ماهي در سواحل جنوبي درياي خزر انجام شد. نمونه برداري بصورت فصلي و از اعماق 5 تا 100متر از آستارا تا بندر تركمن در 8 نيم خط عرضي عمود بر ساحل صورت پذيرفت. هدف از اين مطالعه بررسي وضعيت پراكنش، تراكم و زي توده بين بي مهره گان كفزي در نيم خط ها، عمق و فصول مي باشد. نتايج نشان داد كه يشترين مقدار تراكم و زي توده به ترتيب در نيم خط هاي اميرآباد با ميانگين (±انحراف معيار) 4/7301±7/10931 عدد در متر مربع و نيم خط آستارا با ميانگين (±انحراف معيار3/160± 2/86 گرم در متر مربع بود. اين امر مي تواند به دليل حضورگونه Streblospio gynobranchiata بعنوان يك گونه غيربومي (قدرت سازش پذيري بالا) از راسته پرتاران (بيش از 58 درصد از كل فراواني) در نيم خط امير آباد و صدف دوكفه اي Cerastoderma glaucum (درشت بودن اندازه) از راسته نرمتنان در نيم خط آستارا مرتبط باشد. همچنين اختلاف معني دار بين ميزان تراكم در نيم خط ها (05/0>p) و عدم اختلاف در اعماق و فصول مختلف وجود داشت (05/0p) و در نيم خط ها و فصول مختلف اختلاف معني داري يافت نشد(05/0

This research in line with fish cage culture plan in the southern coast of the Caspian Sea was carried out. Sampling was seasonally in 8 transects at the depth of 5-100 m from Astara to Torkaman areas in 2008-2009. The aim of this study was to investigate the distribution, abundance and biomass of macrobenthic invertebrate. The highest abundance and biomass were found in transects of Amirabad with average 10931.7±7301.4N/m2 and Astara with mean 86.2±160.3g/m2, respectively. This could be due to the presence of alien species into the Caspian Sea, Streblospio gynobranchiata in 2003 and is the dominant population of macrobenthic invertebrate concern up to 58.4% and increased of S. gynobranchiata (high power compatibility) and mussels of Cerastoderma glaucum (large size) is relevant, respectively. The abundance and biomass have fluctuations in different seasons and the highest abundance with average 6280.1±5693.1N/m2 and biomass with mean 66.1±126.9g/m2 was in winter and spring, respectively. A significant difference between abundance and transects (p<0.05), no significant difference between abundance and depth and seasons (p>0.05), significant difference between biomass and depth (p<0.05) and no significant difference between biomass at transect and seasons (p>0.05) were found. Also, according to multivariate analysis of benthic invertebrate on the abundance at various depths revealed that depths of 5, 10 and 20 meters from the importance of certain fisheries in terms of frequency, abundance and biomass of the macrobenthic invertebrate, slope substrate, substrate, close to the beach, the accumulation of nutrients, Nursery ground, feeding ground and Spawning ground is important for different important species in the Caspian Sea. Therefore, the establishment of fish cage culture was recommended more than 20-meter depths according to the plans of fish cage culture in the southern coast of the Caspian Sea of the Iranian Fisheries Organization.