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

W Li,Z Li,H Ding,F Zhang,J Liu,T Zhang

doi:10.3354/aei00198

Abstract

The Chinese soft-shelled turtle Pelodiscus sinensis is a highly valued freshwater spe- cies 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 eco- nomic 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 with- out 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 pres- ence of I. aquatica also has a positive effect on the performance of P. sinensis. Although no signif- icant 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.

Highlights

The Chinese soft-shelled turtle Pelodiscus sinensis is the most common turtle species cultured in China (Li et al 2013)
total phosphorus (TP) concentrations were significantly affected by the presence of Ipomoea aquatica (p < 0.05; Fig. 1C); the mean TP concentration in the I. aquatica cultivation (IAC) treatment was 42.5% lower compared to the control treatment at the end of the experiment
The chemical oxygen demand (CODMn) levels did not significantly differ between the 2 treatments during the whole experimental period (p > 0.05; Fig. 1D), chl a concentration and turbidity were significantly influenced by I. aquatica, with lower mean values in IAC ponds compared to the controls from August to October, respectively (p < 0.05; Fig. 1E,F)

Summary

Introduction

The Chinese soft-shelled turtle Pelodiscus sinensis is the most common turtle species cultured in China (Li et al 2013). There are many approaches to improving a culture environment, and phytoremediation, especially using aquatic plants, is currently attracting much attention. It is considered promising because of its low cost, non-intrusiveness and safety (Li et al 2009, Mook et al 2012). Floating bed technology makes it possible to plant this species on the water surface of fishponds, which improves the culture environment, and provides additional economic benefits (Li & Li 2009)

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Conclusion