Md Ali Haider
Faculty of Fisheries, Hajee Mohammad Danesh Science & Technology University, Dinajpur
Sheik Istiak Md Shahriar
Faculty of Fisheries, Hajee Mohammad Danesh Science & Technology University, Dinajpur
Md Hafiz All Hosen
Faculty of Fisheries, Hajee Mohammad Danesh Science & Technology University, Dinajpur
Mousumi Sarker Chhanda
Faculty of Fisheries, Hajee Mohammad Danesh Science & Technology University, Dinajpur
Mst Masuma Khatun
Faculty of Fisheries, Hajee Mohammad Danesh Science & Technology University, Dinajpur
Water quality parameters, Benthos abundance, Dinajpur district, Bangladesh
Sadar upazila of Dinajpur, Bangladesh
Crop-Soil-Water Management
Water quality, Freshwater, Pond
2.1 Study area and site selection The study was conducted in nine ponds for a period of three months from January 2016 to March 2016. The experimental ponds were selected from sadar upazila of Dinajpur, Bangladesh. In order to observe the physico-chemical conditions and benthic fauna of the ponds, samples were collected at 15 days interval. Ponds were selected by size, shape, water color and surrounding conditions. Present study includes three treatment where treatment 1 (T1) represents small sized pond (5 decimal), treatment 2 (T2) represents medium sized pond (10 decimal) and treatment 3 (T3) represents large sized ponds (15 decimal) and each of them had three replications.
2.2 Study of water quality parameters A number of water quality parameters such as temperature (°C), transparency (cm), dissolved oxygen (mgl-1), pH, total alkalinity (mgl-1), chlorophyll-a (µgl-1), ammonia-nitrogen (mgl-1), phosphate-phosphorus (mgl-1), nitrite-nitrogen (mgl-1) and nitrate-nitrogen (mgl-1) were measured. Water samples were collected within 8.30 to 10.30 am on each sampling day using a tube sampler (3-4ft) in a manner that it is representative of all layers of the water column. Temperature and transparency was measured on the spot and rest of the above parameters was measured in the Water Quality and Pond Dynamics Laboratory, Faculty of Fisheries, Bangladesh Agricultural University, Mymensingh, Bangladesh. A volume of 250 ml of water sample was filtered through glassfibre filter paper (Whatman GF/C) with the help of electronic vaccum pressure air pump for chlorophyll-a measurement. Water temperature was recorded with a celsius thermometer. Transparency was measured with a secchi disc. Dissolved oxygen and pH of the water samples were determined by using a direct reading digital meter (HACH 40d, multiparameter sensor) in the laboratory. Total alkalinity was determined titrimetrically. The concentration of Nitratenitrogen and phosphate-phosphorus of water samples were determined by HACH kit (DR-4000, a direct reading spectrophotometer) using Nitra Ver-6 and Nitri Ver-3 powder pillows. Ammonia-nitrogen was also determined by HACH kit with mineral stabilizer and Nesslar reagent. Chlorophyll-a was measured in a spectrophotometer (DR 6000) at 664 and 750 wavelength.
2.3 Collection of benthos samples The benthic macro-invertebrate samples were collected from 3 different locations of each pond by using an Ekman dredge (covering an area of lower mouth 225 cm). After collecting, the bottom materials were passed through a 0.2 mm mesh sieve in order to separate benthic organisms. Collected organisms were washed and preserved in 10% formalin. Finally, samples were taken to laboratory for further analysis.
2.4 Separation, identification and calculation of benthic fauna Benthic samples were kept in a petri dish and washed with tap water to remove the remaining washable detritus and mud. The samples were then cleared using distilled water. The organisms were separated from each other with the help of sorting needles and fine forceps. Subsequently, the benthic organisms were identified and counted according to different taxonomic groups. The abundance of benthic organism was expressed as density (ind.m-2) by following the formula of Welch (1984).
2.5 Statistical analysis For the statistical analysis, a one-way ANOVA and DMRT (Duncan’s Multiple Range Test) was performed by using the SPSS (Statistical Package for Social Science) version-16. Significance of mean values was tested at 0.05% level.
International Journal of Fisheries and Aquatic Studies 2017; 5(2): 27-32
Journal