Effects of water spinach Ipomoea aquatica cultivation on water quality and performance of Chinese soft-shelled turtle Pelodiscus sinensis pond culture

The Chinese soft-shelled turtle Pelodiscus sinensis is a highly valued freshwater species cultured in China. A 122 d experiment was conducted to assess the effects of water spinach Ipomoea aquatica cultivation in floating beds on water quality, and growth performance and economic return of P. sinensis cultured in ponds. Two treatments, each in triplicate, with and without I. aquatica cultivation were designed. Results showed that the levels of total ammonia nitrogen (TAN), total nitrogen (TN), total phosphorus (TP), chlorophyll a (chl a) and turbidity in treatments with I. aquatica cultivation (IAC) were significantly (p < 0.05) lower than those in treatments without I. aquatica (control). Mean TN and TP concentrations in the IAC treatment were 27.9 and 42.5%, respectively, lower than in the control treatment at the end of the experiment. The presence of I. aquatica also has a positive effect on the performance of P. sinensis. Although no significant difference was found in specific growth rate (SGR) between the 2 treatments, mean survival rates, production and net income were significantly higher in the IAC treatment compared to the control (p < 0.05). These results suggest that I. aquatica cultivation in the pond system of turtles has a synergistic effect on overall economic return and is effective at improving turtle growth performance and water quality.