Comparison of Growth and Production of Green and Red Salanova Lettuce (Lactuca sativa) and Basil (Ocimum basilicum) When Grown in Either Floating Rafts or Media Beds in a Coupled Aquaponic System with Nile Tilapia (Oreochromis niloticus)

This study compared floating raft and media bed aquaponic systems, assessing fish growth, plant growth, and system performance between common system designs. The study consisted of two trials utilizing six replicated aquaponic systems. In each trial, three of the systems were floating rafts (1514 L/system) and three were media beds (1136 L/system). In Trial 1, basil (Ocimum basilicum, ‘Genovese’) and green salanova lettuce (Lactuca sativa, ‘Salanova Green’) plants were stocked, and, in Trial 2, green and red salanova lettuce (Lactuca sativa, ‘Salanova Red’) plants were stocked. Nile tilapia (Oreochromis niloticus) were used in both trials. In Trial 1, no differences (p > 0.05) in fish or basil growth between floating raft (0.28 ± 0.10% daily growth; 55.0 ± 21.2 g/plant fresh weight (FW); 1106 ± 72 g total biomass/system) and media bed systems (0.29 ± 0.20%; 42.1 ± 7.8 g/plant FW; 879 ± 160 g total biomass/system) were found. However, in Trial 1, floating raft systems produced a significant (p < 0.01) increase in green salanova lettuce (123 ± 21.9 g/plant FW; 3327 ± 256 g total biomass/system) as compared to plants grown in media beds (94.4 ± 35.3 g/plant FW; 2,356 ± 260 g total biomass/system). In Trial 2, no differences (p > 0.05) in fish growth between floating raft (0.50 ± 0.13% daily growth) and media bed systems (0.50 ± 0.01% daily growth) were found; however, floating raft systems produced a significant (p < 0.01) increase in both green and red salanova lettuce individual weight (176.0 ± 34.0 g/plant FW; 169.3 ± 43.6 g/plant FW) as compared to media bed systems (79.2 ± 25.3 g/plant FW; 96.4 ± 22.6 g/plant FW). Green lettuce had a significant (p < 0.01) increase in average total biomass within floating raft systems (3662 ± 350 g total biomass/system) as compared to media beds (1576 ± 474 g total biomass/system). This study highlights the need for further investigation into system design and effects on plant and fish growth to allow producers to make informed decisions when planning an operation.