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Assessment of diurnal fluctuation of water quality parameters in different types of ponds In Rupandehi district, Nepal

Agriculture and Forestry University, Nepal

Abstract

The number of farmers involved in fish farming is gradually increasing in Nepal, especially in the Terai region where fish are cultured in earthen ponds, concrete ponds and plastic ponds in intensive or semi-intensive way. Assessment of diurnal fluctuation of water quality parameters was carried out in 18 selected ponds from Siyari Municipality of Rupandehi district, Nepal in the year 2021. The treatment consisted of pond type as between-subject factor with six earthen nursery ponds, six earthen production ponds and six plastic production ponds. Data were taken by using Aquaread, a multi-parameter water quality testing meter, at dawn (6 AM), noon (12 PM), dusk (6 PM) and night (2 AM), with Time as within-subject factor. Ten repeated observations were taken on cloudy and sunny days during three summer months viz. March, April and May. Field determination of physical (temperature and total dissolved solid) and chemical (pH, dissolved oxygen, salinity, electrical conductivity and oxygen reduction potential) properties of water was carried out. Statistic values of mean and range were computed and represented graphically using MS-Excel. Variation in each parameter at different sampling hours in three types of ponds were compared by Repeated Measures Analysis of Variance (ANOVA) using R-studio which showed that the values varied with time and day of observation, but not with pond type. Pairwise comparison for each significant factor explained that the parameters vary significantly between daytime and morning/nighttime. Results of T-test showed value difference between cloudy and sunny days. There was a linear correlation among Temperature, pH, dissolved oxygen and oxygen reduction potential with greater diurnal fluctuation for all ponds. Earthen nursery ponds had statistically higher values of total dissolved solid, electrical conductivity and salinity and these parameters were highly correlated. Lower mean absolute percent error for best fitted linear regression model depicted good predictability of pH, electrical conductivity, dissolved oxygen and oxygen reduction potential for different time of a day. This research observed the fluctuation of water quality parameters at certain time interval thus opening up the scope for improvement in water quality at local management conditions.

Keywords: Aquaculture, dissolved oxygen, ph, temperature, total dissolved solids, water quality

Contact Address: Soniya Bashyal, Agriculture and Forestry University, Bharatpur-12 Thani Chowk, 44200 Bharatpur, Nepal, e-mail: bashyalsoniya77gmail.com