Synchronizing use of sophisticated wet-laboratory and in-field handheld technologies for real-time monitoring of key microalgae, bacteria and physicochemical parameters influencing efficacy of water quality in a freshwater aquaculture recirculation system: A case study from the Republic of Ireland

There has been growing interest in exploiting microalgae as a natural process for low cost wastewater treatment and for water quality control and remediation in aquaculture. This constitutes the first study to report on a strong relationship between use of sophisticated wet-laboratory flow cytometry equipment and in-field AlgaeTorch® technologies for determining microalgae and bacteria population dynamics in a freshwater pill-pond aquaculture farm over a 10-month monitoring period producing Eurasian Perch, Perca fluviatilis, in the Republic of Ireland. Nitrate levels and temperature were the most significant factors influencing microalgae numbers in rearing and treatment ponds as determined by Principle Component Analysis. Variance in climate, namely drought conditions that occurred during monitoring period, did not affect microalgae or microbial numbers. Chlorophyta, Bacillariophyta and Cryptophyta were the most dominant algal divisions observed in this recirculating aquaculture system, many of these are recognized as a natural source of beneficial prebiotics for fish. Determining baseline microalgal profiles in rearing water, followed by elucidating physicochemical parameters governing wastewater treatment performance, can inform future intensification and diversification of freshwater aquaculture by exploiting and replicating knowledge of favourable algal-microbial ecosystems. Furthermore, holistic datasets can be utilised for smart agriculture by way of informing management tools for future remote monitoring and decision-making by producers.