Spatiotemporal Dynamics of Vibrio Communities and Abundance in Dongshan Bay, South of China

Abstract

The Vibrio genus inhabit estuarine and marine ecosystem throughout the world and can cause severe infections in humans and animals. Previous studies have demonstrated the dynamics of Vibrio at both community and population levels and assessed the close relationship between environmental factors and Vibrio diversity and abundance, such as temperature, salinity, and dissolved oxygen. It is also generally believed that aquaculture is the fastest-growing food sector, which is also applying great environmental impacts on microbial communities in aquatic ecosystems. However, our understanding of the spatiotemporal quantification of Vibrio throughout the four seasons in the aquaculture zone and response to environmental factors remains poor. To explore the spatiotemporal distribution and abundance of the Vibrio community with their related environmental factors and detect the relationships among them, we collected 10 seawater sites spanning four seasons across the whole year in Dongshan Bay for investigating the Vibrio community dynamics. Marked differences in diversity and abundance of the Vibrio community were observed between seasons, which were mainly driven by temperature, dissolved oxygen, nitrate, and nitrite. qPCR analysis showed that Vibrio abundance was most abundant in the summer (5.37 × 106 copies/L), compared with the autumn (4.58 × 106 copies/L), spring (1.18 × 106 copies/L), and winter (1.55 × 104 copies/L). A total of 22 Vibrio operational taxonomic units (OTUs) and 28 species were identified by universal bacteria 16S rRNA gene and cultivation methods, with Vibrio fortis the dominant in these aquaculture areas. To summarize, our present study is one of the few studies to research the occurrence of Vibrio in marine aquaculture of South China, and the results indicate that Vibrio are widely distributed in aquaculture environment and that a further risk assessment is needed to be conducted.

Disentangling the abundance and structure of Vibrio communities in a semi-enclosed Bay with mariculture (Dongshan Bay, Southern China)

“…Mariculture is one of the main reasons due to low water exchange and large inputs of animal food and excrements in this area. Our previous study [52] confirmed that input of nutrients resulted in the highest diversity and significant temporal changes of the Vibrio community in summer. As a consequence, factors affecting the health of this important coastal ecosystem are constantly changing, urging to better understand the dynamics of especially pathogenic Vibrio species.…”

“…Water temperature, pH, salinity, dissolved oxygen (DO), and total dissolved solids (TDS) were measured in situ at each sampling site with a multiparameter water quality checker (Horiba U-50, Horiba Co., Kyoto, Japan). Chemical parameters comprised concentrations of nitrate (NO 3 − ), nitrite (NO 2 − ), ammonium nitrogen (NH 4 + ), and phosphate (PO 4 3− ) which were measured using standard protocols [52] .

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“…One L of seawater was filtered through 0.22 μm filter units (GSWG047S6, Millipore, Burlington Unites States) and stored at − 80 °C for later DNA extractions [52] . Total DNA from filters was extracted using the FastDNA Spin Kit for Soil and a FastPrep-24 Instrument (MP Biomedicals, Irvine, United States) according to the manufacturer’s protocol.…”

“…Stronger and more frequent coastal storms or cyclones, higher temperatures, floods and droughts, salinization of upstream rivers, eutrophication due to excess nutrients input from an increase in population size pose a considerable threat to water and food security [54] . Yet, impacts of environmental factors on Vibrio population dynamics in mariculture areas have been rarely studied [31] , [52] . Our research in Dongshan Bay reveals that diversity and abundance of Vibrio species usually fluctuate seasonally with an increasing abundance in summer [52] .…”

“…Yet, impacts of environmental factors on Vibrio population dynamics in mariculture areas have been rarely studied [31] , [52] . Our research in Dongshan Bay reveals that diversity and abundance of Vibrio species usually fluctuate seasonally with an increasing abundance in summer [52] . Similar results have been reported for other Vibrio studies using either culture dependent or independent methods [7] , [21] , [39] , [47] .…”