اسم المؤلف:
ازهار عبد الحميد عبد الحسن
اسم المشرف:
مؤيد جاسم ياس العماري | عدي جاسم عبد الرزاق
المستخلص:
The present study was carried out in AL - Hilla River near Al mahaweel district in the middle of Iraq during autumn 2016 to summer 2017. The study included a collection of high density from microzooplankton by use special device then identified and used it as live food for early feeding common carp larva (Cyprinus carpio). The environmental factors of Hilla river tested for four seasons and ranged between 6 - 44 ˚C of air temperature, 9.5 - 30 ˚C of water temperature, 7.03 - 8.58 of pH, 921 - 1090 µm/cm of conductivity, 654.33 - 772.00 mg/l of total dissolved solids and 550.00 - 636.33 of salinity, 5.43 - 13.03 mg/l of total suspended solids, 7.5 - 10.31 mg/L of dissolved oxygen, 1.96 - 6.30 mg/l of BOD5, 1.61 - 2.49 m/s of water velocity, 5.17 - 16.80 µg/L of chloropyll - a - . The taxonomic and ecological study is done to the microzooplankton specially rotifer. There are few studies of rotifer in Hilla river, The result showed that the density of rotifera was ranged between 23ind. /L in the summer season to 65.66 ind. /L in winter season, included 65 rotifer taxa (62 species +2genera +1 class) were recorded in this study, 10 taxa (9 species + 1 genus) were recorded for the first time in Iraq and 14 taxa (13 species + 1 genus) were recorded for first time in Hilla River compared with available local studies. Keratella tropica showed the highest density of the rotifera, Lecane genus showed the highest species number (10 species). Canonical correspondence analysis showed Physico - chemical parameters of water affected on the density of rotifer both positively and negatively. There was positive significant correlation between density rotifer with electrical conductivity, total dissolved solids, and salinity, while pH showed the lowest effect on the density of rotifer than other environmental factors. Different species of rotifer showed some variations of the correlation with environmental factor, such as the density of Bdelloidea class correlated positive significant correlation with water temperature, while Keratella cochlearis species negative significant correlation with water temperature. Special system (multi - filtration system) designed and made by researchers in our study for collection high density of microzooplankton with size sample range between 50 - less 200 µm, with short time, less effort and low cost. The multi - filtration system that consists of three stages : pumping stage, multi - filtration stage and sample collection stage. The density of the samples was measured seasonally by comparing the density of the microzooplankton in Hilla river and the density of the microzooplankton sample obtained by the multi - filtration system. The highest density of multi - filtration system rotifer was 1023033 ind./L and the highest density of multi - filtration system total microzooplankton was 1052000 ind/L and measured chlorophyll - a - of sample multi - filtration system that ranged between 23.54 - 1931.09 µg/L. The density of rotifer and total microzooplankton that collect by the multi - filtration system were concentration up to 20222.22, 17558.81 times than what is in the river. After collection of the high density of microzooplankton by using the multi - filtration system, this microzooplankton was used as live food for early feeding fish larvae. A special experiment was designed to feed common carp of fish larvae (Cyprinus carpio) using three types of food : first live diet collected by the multi - filtration system that microplankton most rotifer, second soybean meal and third mixed food (rotifer and soybean meal). Some growth indicators for fish larvae were studied; the results showed that the highest growth rate and best survival rate were larvae fed on live food, highest increased weight and increased length, relative growth rate, specific growth rate and lowest survival rate (33.53 mg, 3.33mm, 87.78, 30.11, and32.38 % respectively) for larvae fish feeding on rotifera, while lowest increased weight and increased length, relative growth rate, specific growth rate and lowest survival rate (27.00mg, 1.43mm, 85.23, 27.39, and 61.90 % respectively) for fish larvae feeding on soybean meal.
