Abstract:
Fluctuation in dissolved oxygen concentration (DO) is one of the major water quality parameters
influencing aquaculture production. Low levels of DO in earthen ponds cause stress in cultured
fish resulting to poor appetite, growth performance and greater exposure to diseases that
subsequently leads in low fish yields. This study aimed to investigate the diurnal variations of
DO concentrations in a high rate algal pond (HRAP) system to ascertain the potential use of its
effluent in aquaculture production. The specific objectives were to: i) determine the DO
concentration of a HRAP system over a 12 hour cycle, iii) to determine the influence of
temperature and light on DO concentration and, iii) find out if diurnal variation of DO
concentration is within the requirement to support fish culture. The study employed a HRAP
system constructed and operated at the Faculty of Natural Resources and Environmental
Sciences, Namasagali campus, Busitema University. DO concentration and temperature were
measured on-site using a multi-meter probe while light intensity data was obtained from an online
meteological
site.
Data
was
collected
at
different
time
intervals
i.e.
6:00 AM, 12:00 NOON
and 6:00 PM for three weeks from 23/06/2024 to 17/07/2024. Results revealed that DO
concentrations varied significantly during the 12 hour monitoring period. Mean DO
concentrations recorded were 5.14±0.20 mg/L, 8.53±0.14 mg/L and 7.14±0.14 mg/L at 6:00 AM,
12:00 NOON and 6:00 PM respectively. Mean DO concentration varied significantly with
temperature and light intensity throughout the monitoring period with highest DO levels
recorded at midday when temperature and light intensity were at maximum. Meanwhile, despite
the diurnal variation in DO, mean DO levels were within the recommended range for culture of
the commonly farmed tropical fish species i.e. Oreochromis niloticus and Clarias gariepinus.
Results of the present study suggest potential application of HRAP system for use in fish ponds
to overcome DO concentration problems and the result improvement in fish health and
production.
