Using Ipomoea aquatic as an environmental-friendly alternative to Elodea nuttallii for the aquaculture of Chinese mitten crab.

Linlin Shi,Lijuan Mei,Meijuan Jin,Changying Lu,Mingxing Shen,Haihou Wang,Shixue Yin,Xingwei Zhou

doi:10.7717/peerj.6785

Abstract

Elodea nuttallii is widely used in Chinese mitten crab (CMC) rearing practice, but it is not a native aquatic plant and cannot endure high temperature. Thus, large E. nuttallii mortality and water deterioration events could occur during high-temperature seasons. The aim of this study was to identify the use of local macrophytes in CMC rearing practice, including Ipomoea aquatic and Oryza sativa. A completely randomized field experiment was conducted to investigate the crab yield, water quality, bacterioplankton community and functions in the three different systems (E. nuttallii, I. aquatic, and O. sativa). Average crab yields in the different macrophyte systems did not differ significantly. The I. aquatic and O. sativa systems significantly decreased the total nitrogen and nitrate-N quantities in the outflow waters during the rearing period compared to the E. nuttallii system, and the I. aquatic and O. sativa plants assimilated more nitrogen than the E. nuttallii plant. Moreover, the significant changes of bacterioplankton abundances and biodiversity in the three systems implied that cleanliness of rearing waters was concomitantly attributed to the differential microbial community and functions. In addition, principle component analysis successfully differentiated the bacterioplankton communities of the three macrophytes systems. Environmental factor fitting and the co-occurrence network analyses indicated that pH was the driver of bacterioplankton community structure. Functional predictions using PICRUSt (v.1.1.3) software based on evolutionary modeling indicated a higher potential for microbial denitrification in the I. aquatic and O. sativa systems. Notably, the O. sativa plants stopped growing in the middle of the rearing period. Thus, the I. aquatic system rather than the O. sativa system could be a feasible and environmental-friendly alternative to the E. nuttallii system in CMC rearing practice.

Highlights

The Chinese mitten crab (CMC), Eriocheir sinensis, is considered an invasive species in Europe and North America (Brodin & Drotz, 2014; Hanson & Sytsma, 2008), but it is an expensive delicacy in Asia (Chen & Zhang, 2007; Food and Agriculture Organization of the United Nations (FAO), 2019)
I. aquatic, O. sativa, and E. nuttallii were grown in separate sub-ponds with three replicates per plant using a completely randomized design
Elodea nuttallii is routinely cultivated in ponds used for mitten crab aquaculture

Summary

Introduction

The Chinese mitten crab (CMC), Eriocheir sinensis, is considered an invasive species in Europe and North America (Brodin & Drotz, 2014; Hanson & Sytsma, 2008), but it is an expensive delicacy in Asia (Chen & Zhang, 2007; Food and Agriculture Organization of the United Nations (FAO), 2019). In 2014, 796,621 tons of farmed CMCs were produced (Zeng et al, 2013); crabs were primarily bred in ponds and lakes (Zeng et al, 2013). The mitten crabs produced in Yangcheng Lake, Suzhou, China, are of high quality and have high economic value (Gu et al, 2013). Most of the crabs produced in Yangcheng Lake are exported to Shanghai, Hong Kong, and high-profit foreign markets. Aquatic plants assimilate excess nutrients, improve water cleanliness, and absorb solar radiation to maintain cool water temperatures. These properties increase crab growth, yield, and quality (Zhan & Yang, 2015)

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