Desempenho produtivo e qualidade da água em um sistema de aquaponia contendo tilápias em diferentes densidades de cultivo, alfaces e macrófitas aquáticas

Abstract

The continuous growth of the world population and the consequent increase in the demand for food and water imply the need for greater production of food and requires investment in research as more productive and environmentally responsible farming systems. The integrated system of fish and vegetable production, called aquaponia, allows the reuse of nutrients present in the residual water of fish farming and which would be discarded from the system, in the growth of vegetables, providing the reuse of water in the cultivation of fish. In this context, the objective of this research was to evaluate an aquaponics system, by determining the ideal stocking density of Nile tilapia, Oreochromis niloticus, and the quality of the water and removing nutrients from the fish effluent by the vegetable Lactuca sativa L. e by the aquatic macrophyte Landoltia punctata, aiming at its best technical and productive performance. The productive performance of fish and vegetables was evaluated, as well as their nutritional quality and the quality of water and removal of nutrients through the use of macrophytes in the tertiary treatment system. The study was conducted in experimental modules installed at the Symbiotec Aquaponics Laboratory - Aquicultura e Sistemas Integrados de Produção Ltda. in Piracicaba - SP. The results showed that different densities of cultivation of Oreochromis niloticus, as well as the introduction of the macrophyte Landoltia punctata in the treatment system, did not interfere in the productive performance of the fish, evidencing the viability of raising tilapia in high density integrated (32 kg/m³) with the hydroponic lettuce system, with water recirculation. The association between the nitrifying bacteria in the biofilter, the hydroponic cultivation of lettuce and the introduction of the macrophytes Landoltia punctata proved to be efficient in treating the effluent of the intensive fish farming system and maintaining the quality of the water necessary for the cultivation of tilapia, mainly reducing ammonia levels, toxic to fish. As for the lettuce productivity, it was found that the residual water from the tilapia farming system proved able to provide sufficient quantities of almost all the nutrients necessary for the good development of lettuce in hydroponic cultivation, thus dispensing the need for supplementation with chemical fertilizers, but only the T4 treatment (114 g of feed/m2 of vegetable cultivation) showed results compatible with that expected in commercial production.