Do stocking densities affect the gut microbiota of gibel carp Carassius auratus gibelio cultured in ponds?

Z Zhou,S He

doi:10.4172/2155-9546.s1-003

Abstract

The aim of the present study was to evaluate the intestinal microbial communities of gibel carp (Carassius auratus gibelio) cultivated in two beach ponds at different stocking densities. The two ponds were both ~3.33 hm 2 in acreage and ~1.5 m in depth. The stocking densities included one intensive with 2 fish m –3 while the other treated as semi-intensive with 1 fish m –3 . The gut microbiota (both allochthonous and autochthonous) were sampled after 135 days of feeding. Denaturing gradient gel electrophoresis (DGGE) of PCR-amplified 16S rRNA gene segments was used to evaluate the bacterial community. Actinobacteria, Cyanobacteria, Firmicutes, Fusobacteria, Proteobacteria and some unclassified_bacteria taxa were identified in gut samples and feed. Similar bacterial communities (C s=0.83) were observed with respect to the autochthonous and allochthonous gut microbiota of gibel carp cultured in the intensive culture pond. In contrast to these results, some difference (C s =0.61) was observed in the gut microbiota of fish reared in the semi-intensive culture pond. Our results indicated that the difference in the bacterial communities between allochthonous bacteria and gut associated bacteria of gibel carp was not constant and was modulated by the stocking density.

Highlights

In order to expand aquaculture production, the increase in stocking density is of high importance because the cultured area in China has decreased from 7,281,252 ha to 6,549,932 ha from 2004 to 2008 [1]
The 16S rDNA V3 Denaturing gradient gel electrophoresis (DGGE) fingerprints were used to profile the microbial communities of feed and in the gastrointestinal tract of gibel carp cultivated at high density (HD) and low density (LD) (Tables 1–3 and Figure 1)
Similar bacterial communities (Cs=0.83; Table 1) were observed with respect to the autochthonous (Auto) and allochthonous (Allo) gut microbiota of gibel carp cultured in the HD pond (Auto-HD vs. allochthonous gut microbiota in HD pond (Allo-HD))

Summary

Introduction

In order to expand aquaculture production, the increase in stocking density is of high importance because the cultured area in China has decreased from 7,281,252 ha to 6,549,932 ha from 2004 to 2008 [1]. It has been reported that higher stocking density could affect the production and nutritional status, health and stress indicators of the fish [2,3]. There are present of many bacteria that have adhered to the mucosal surface of the intestine which may contribute to indigenous microbiota called autochthonous microbiota [4]. These microbiota play an important role in the health and disease control of fish, which is affected by the developmental stages, diet and environmental conditions [4,5,6]. Dietary supplementation with Cu2+-exchanged montmorillonite significantly reduced (P < 0.05) the total intestinal aerobic bacterial counts and affected the composition of intestinal microflora with a tendency of Aeromonas, Vibrio, Pseudomonas, Flavobacterium, Acinetaobacteria, Alcaligence, Enterobacteriaceae decreasing as compared with control [9]

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Conclusion