Vol.:(0123456789) 1 3 International Journal of Energy and Water Resources (2021) 5:379–389 https://doi.org/10.1007/s42108-021-00141-5 ORIGINAL ARTICLE Using seasonal variability of water quality parameters to assess the risk of aquatic pollution from rainbow trout fsh farms in Greece T. Mavraganis 1  · M. Tsoumani 2,4  · M. Kolygas 3  · M. Chatziefstathiou 4  · C. Nathanailides 1 Received: 22 April 2021 / Accepted: 4 August 2021 / Published online: 6 September 2021 © Islamic Azad University (IAU) 2021 Abstract Sustainable development of fresh water (FW) aquaculture requires minimal environmental impact, by reducing the waste discharged into the surrounding waters. To assess the water quality status and impact of fow-through trout farming in the Louros river (NW Greece), a seasonal evaluation of the trout production in the river was performed. Seasonal samples of river water entering and discharged were obtained to monitor some water quality parameters. The parameters were temperature, pH, ammonium, phosphate, dissolved oxygen (DO), biochemical oxygen demand (BOD 5 ), electrical conductivity (EC), total dissolved solids (TDS), total nitrogen (TN), and total phosphorus (TP) of fow-through trout farms alongside the river. All monitored parameters indicated minimal environmental impact of the fsh farms; pH ranged from 7.57 to 8.03, TDS ranged from 151.43 to 242.56 mg/L, DO ranged from 6.28 to 9.16 mg O 2 /L, BOD ranged from 0 to 2 mg O 2 /L. As for the nutrients, mean values were below each limit set for freshwater systems. NH 4 -N ranged from 0 to 0.28 mg/L, and PO 4 -P ranged from 0.15 to 0.42 mg/L. Based on the comparison of water quality parameters in the outlets and on the Environmental Impacts and Environmental Quality Standards (EQS), it can be concluded that trout fsh farms had no signifcant environmental impact on the river water quality during any of the tested seasons. All parameters presented strong increasing trends during spring and summer and low decreasing trends in autumn and winter. In conclusion, the results indicated minimal aquaculture impact on river Louros water quality. Keywords Freshwater aquaculture · Water quality · Environmental impact · Rainbow trout · Greece Introduction Aquaculture production and the land‑based systems The aquaculture industry is highly developed in Greece, and in the last 20 years, especially, it has been highly ranked among European production standards with marine aqua- culture contributing 125,772 tons per annum (2018) to the world aquaculture market. Freshwater systems situated mostly in land-based facilities adjacent to rivers usually focus on trout and limited quantities of carp in raceways (FAO, 2020). More than 78 farms of freshwater aquacul- ture are present on the mainland. Seventy-two organiza- tions are working with lagoon aquaculture, mostly working as co-operatives, which occupies a space of 40,000 ha with a production of around 600 tons. The number of farms has been relatively stable and did not expand during the current period of economic problems in Greece (F.G.M., 2017). Environmental Impacts and Environmental Quality Standards (EQS) Several parameters can contribute to the environmental impact of aquaculture including energy consumption, pro- duction of equipment and feed, as well several other opera- tional features of a fsh farm (Konstantinidis et al., 2020). The potential aquatic pollution of aquaculture can be divided into two categories depending on the water system and the * C. Nathanailides nathan@uoi.gr 1 Department of Agriculture, University of Ioannina, Arta campus, TK 47100 Arta, Greece 2 Hydrobiological Station of Ioannina, Hellenic Ministry of Rural Development and Food, TK 45500 Terovo, Ioannina, Greece 3 Laboratory of Ichthyology and Ichthyopathology, Veterinary School, University of Thessaly, 43100 Karditsa, Greece 4 Panhellenic Society of Technologists Ichthyologists, R&D, Piraeus, Greece