Investigation of bacterial diversity and pathogen abundances in gibel carp (Carassius auratus gibelio) ponds during a cyprinid herpesvirus 2 outbreak

Abstract

Cyprinid herpesvirus 2 (CyHV‐2) infection is detrimental to gibel carp health and may result in severe economic loss in freshwater aquaculture. However, information regarding the interaction of this pathogen with the aquatic environment is scarce. In this study, quantitative polymerase chain reaction (qPCR) and high‐throughput sequencing were used to determine the abundances of pathogens and bacterial community compositions in two aquaculture ponds in Jiangsu Province, China. The results indicate that the concentrations of six selected pathogens were higher in the water than in the sediment and that these concentrations peaked during disease outbreak. In total, 8,326 and 18,244 operational taxonomic units were identified from water and sediment samples, respectively. The dominant phyla were Proteobacteria, Actinobacteria, Cyanobacteria, Bacteroidetes, and Chlorobi in water samples and Proteobacteria, Firmicutes, Actinobacteria, Chloroflexi, and Bacteroidetes in sediment samples. Bacterial communities were similar at the phylum level in different ponds, although significant differences were observed at the genus level. In addition, bacterial diversity was associated with environmental factors (temperature, chemical oxygen demand, NO2 −‐N, NO3 −‐N, and NH4 +‐N) in the pond where the outbreak occurred. Additionally, CyHV‐2 abundance was positively correlated with dissolved oxygen levels and Aeromonas spp. abundance in pond water (p < .01). This study provides comprehensive insight into the mechanisms of interaction between potential pathogens and the freshwater environment of aquaculture ponds during CyHV‐2 disease outbreaks. Furthermore, the results from this study can contribute to improvement of the aquatic environment and establishment of disease prevention and control measures.

Planktonic bacteria in white shrimp ( Litopenaeus vannamei ) and channel catfish ( Letalurus punetaus ) aquaculture ponds in a salt‐alkaline region

“…abundance in pond water (Gao et al . 2019). In our study, alpha diversity indexes in the aquaculture ponds were lower than those in the source water, which can be attributed to the aquaculture operations.…”

Transferred Bacterial Community on the Potentially Pathogenic Bacteria among Aquatic Water, Plant Root, and Sediment When Planting with Chinese Herbs

“…CyHV-2 abundance is positively correlated with dissolved oxygen levels and the presence of abundant Aeromonas spp. in pond water [21]. Plant roots with stronger dissolved oxygen levels and biological nitrification inhibition capacities suppress the populations of Nitrospira in the rhizosphere, Comparisons were also performed to identify the microorganisms that can transform in different media at 30 d (water, roots, and sediment).…”

“…Nitrospirae sig-nificantly increased and decreased in the HcT1 and Jr root groups, respectively, in the present study, with our previous study results showing that HcT1 and Jr are involved in nitrogen and phosphorus removal. The total phosphorus concentration in the pond sediment was the main reason for cyanobacterial blooms [23], with the Ruminococcaceae, Gemmatimonadetes [24], and Cyanobacteria (sediment) [21] populations increasing in the Jr group [25], with Jr releasing yellow allelochemicals, which may inhibit the growth of algae (like cyanobacterial blooms) [26] and nitrite-oxidizing bacteria (Nitrospirae) [27]; our previous study showed that Jr may have potent algae prevention effects in ponds [4]. However, the abundance of some anti-stress bacteria, such as Chlorobi and Fusobacterium, increased.…”