A Importância Do Fósforo Na Produção Ambientalmente Sustentável Em Aquicultura Continental

Artificial floating islands as a tool for the water quality improvement of fishponds

“…The limnological characteristics of the water supply, such as water temperature (26.4ºC), pH (6.25), turbidity (25 NTU), conductivity (50 μS cm -1 ), dissolved oxygen (6.88 mg L -1 ) and total dissolved solids (0.034 mg L -1 ), were regularly monitored during the study period and are detailed in Osti et al (2020). The semi-intensive production system was used for the grow-out period of male Nile tilapia (Oreochromis niloticus), sexually reversed, with an initial average weight of 22.64 g, stocked at the density of three fish per m 2 .…”

“…The artificial floating islands installed in the fishponds were built with 2 m² each, using PVC pipes and fishing nets, easy-finding and low-cost materials, occupying 10% of the fishpond area. The details of the structure and dimensions of the AFIs are described in Osti et al (2020). According to the aforementioned authors, the floating artificial islands model is easy to install and maintain, robust enough to withstand macrophyte management, and it is not necessary to remove it for fish measurements throughout the grow-out period.…”

“…Additionally, overfeeding or the use of unbalanced feed reduces the absorption of nutrients by fish, which can result in excess of organic matter and nutrients in production systems, with direct consequences on water quality, favoring their assimilation by phytoplankton and aquatic macrophytes. The increase in phytoplankton abundance may lead to the reduction in water transparency and depletion of dissolved oxygen, which can compromise the productivity performance and increase fish mortality (Cyrino et al, 2010;Boyd, 2016;Mercante et al, 2020).…”

“…The adoption of Best Management Practices (BMPs) and the development of technologies that combine the necessary speed for an economically viable production, without compromising the water quality of fishponds, must be adopted to ensure a suitable environment for the fish, as well as the conservation of aquatic environments, promoting the sustainability of the activity. The technology of artificial floating islands (AFIs) is an innovative variant of the built wetland system and consists of the elaboration of floating rafts that are colonized by emerging and floating aquatic macrophytes, with the roots of plants submerged below the water surface (Afzal et al, 2019;Spangler et al, 2019;Osti et al, 2020). In these systems, the improvement of water quality is due to the direct assimilation of nutrients by the root system of plants, but also by the biofilm formed by algae, bacteria and other microbes that adhere to the entire surface area of the AFIs (roots of the plants).…”

“…The technology of AFIs has been tested in the control of pollution from different activities, such as swine waste (Hubbard et al, 2004); in rainwater drainage systems (Headley et al, 2008;Lynch et al, 2015); and at acid mine drainage sites (Gupta et al, 2020). Furthermore, the adequacy of this technology was also tested to control the release of nutrients by fishponds' effluents (Osti et al, 2020). These authors concluded that AFIs technology implemented in fishponds can reduce the load of total nitrogen and total phosphorus exported by 66% and 27%, respectively, showing its efficiency.…”