Açai palm, Euterpe oleracea, seed for aquaponic media and seedling production

The overexploitation of limited resources combined with the excess of residue produced by agroindustry are worldwide concerns that are steering human activities towards cleaner and more efficient production methods. This is the first study to verify the possibility of using discarded açai seed as growth media for water biofiltration and seedling production in an Amazonian aquaponic system with tambaqui, Colossoma macropomum. To conduct the evaluation, three flooding levels (5,10 and 15 cm) with constant flow through the açai seed bed (13 cm depth) and a control (without açai seed) were performed for 30 days and the effects on water quality, vegetable and fish growth performance were analyzed. After 28 days, mean total ammonia was lower than 1 mg L−1 in treatments with açai seed, and was higher than 5 mg L−1 at control during the entire experiment. While phosphate and nitrite were not significantly affected, nitrate was lower at 15 cm of water flow. The açai seed decreased dissolved oxygen, total dissolved solids and conductivity, and increased pH and alkalinity. After 22 days, superficial açai germination was 2.63 and 3.07 times higher at the 10 cm flood level than at 5 and 15 cm respectively, though higher seedling growth was observed at 5 cm. After 30 days, no significant differences were observed in tambaqui performance, which reached more than 1 kg and at a rate of almost 10 g per day. In this context, açai seed is capable of removing nitrogen compounds, producing a high quantity of early seedlings and without negatively affecting tambaqui growth.