Browsing by Author "Schol, Nikki Floor"
Now showing 1 - 1 of 1
Results Per Page
Sort Options
- Performance of Ulva sp. (Chlorophyta) at different stocking densities in recirculating aquaculture systemsPublication . Schol, Nikki Floor; Galvão, Helena M.; Quintã, RaquelAquaculture may be responsible for deterioration of surrounding natural waters, so focus of research in this field to improve sustainability is directed on the recycling of wastewater in cultivation systems. Recirculating Aquaculture Systems (RAS) show promise, but fish production is often limited because of low water quality due to the accumulation of metabolic waste. Water quality may be improved by integrating seaweed as they effectively clean the water by remediating nutrients. This study explored how to optimize RAS by measuring growth and yield performance of Ulva sp. and how this relates to water quality. An integration experiment was conducted by adding an Ulva filtration unit to outdoor RAS at different fish densities. Seaweed performance was compared by calculating growth rate, biomass yield, and nitrogen removal by biomass of the Ulva stocking densities 1, 2, and 3 kg FW m-2. Additionally, water quality parameters were compared, involving biochemical measurements and fluorescent microscopic microbial counts. The results showed that the highest growth rate was measured for Ulva stocking density 1 kg FW m-2 and the highest biomass and N yield for 2 kg FW m-2. Performance was lower with an increased fish density. The high fish density resulted in lower water quality in the RAS, with a significantly higher abundance of heterotrophic bacteria and bacterivores, a higher level of ammonia, and lower pH. No difference was detected in dissolved oxygen and phytoplankton abundance. These results demonstrate that lower Ulva stocking densities show higher performance in IRAS, but more research is required in improving the cultivation environment of Ulva to increase its capability to enhance water quality parameters.