A thesissubmitted in partial fulfillment of the requirements for the degree of Master of Science in Aquaculture and Aquatic Resources Management, School of Environment, Resources and Development

Thesis (M.Sc.) - Asian Institute of Technology, 2017

This study aimed at analyzing the plankton dynamicsintwo different systems; biofloc and aquamimicry systems.The experiment was conducted in six tanks. Treatments are either biofloc system withtapioca starch as a carbon source or aquamimicry system with fermented rice bran. Eachtreatment was randomly assigned to three replicates.The experiment was conducted 63 days with zero water exchange.Sex reversed Tilapia fry (average weight is 0.25 g) was stocked atthe density of 1000 fry/m3after 7 days of biofloc development. Species identification and counting wasmeasured in 2 replicates per one sample. Concentrations of chlorophyll a (chl-a) analysis was performed every day before fish stocking then every 3 days.Additionally, phytoplankton species and densityinside the fish stomachs were examined.Phytoplankton biomass as Chlorophyll-a measurement in aquamimicry system was higher than biofloc system, on the other hand, the density of phytoplankton in aquamimicry appeared to be lower than biofloc system even though there were no statistically difference among these systems.There was nosignificantrelationship between phytoplankton biomass and phytoplankton density at the P<0.05 level.Population of Cyanophyceae and Chlorophyceae comprised the major part of the density compared to other groups in both systems. The relationship between phytoplankton density and water quality parameters, microbial activity and energy input appearedto be better in aquamimicry system because significant relationship(P<0.05)between phytoplankton density and alkalinity, free carbon dioxide, microbial activity and number of bacteria were found only in aquamimicry system. On the other hand, relationship betweenphytoplankton density and nitrate was significant (P<0.05)only in biofloc system due to number of phytoplankton in the system. There was no relationship between number of phytoplankton and temperature but were significant relationship (P<0.05)with pH, DO, floc volume andtotal energy input. There were no significant on phytoplankton density in fish stomach between before and after feeding time, and also among treatments. Cyanophyceae and Chlorophyceae inside the gut were noted in both systems.In this current study, the relationship between phytoplankton and some water quality parameters was not clearly revealed. However, Aquamimicry system is a new technology for tilapia culture andcan provide sustainable tool to solve environmental, social and economic problems concurrently. Additionally, scientists and fish farmers can improve and apply this technology to aquaculture systems in the future.