Decadal monitoring reveals an increase in Vibrio spp. concentrations in the Neuse River Estuary, North Carolina, USA.

Brett Froelich,Brett Froelich,Rachel Noble,Denene Blackwood,Rachel Noble,Kellen Lauer,Kellen Lauer,Raul Gonzalez,Denene Blackwood,Iddya Karunasagar

doi:10.1371/journal.pone.0215254

Brett Froelich, Brett Froelich + Show 8 more

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https://doi.org/10.1371/journal.pone.0215254

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Abstract

A decade long study was conducted to investigate the ecological, biological, and temporal conditions that affect concentrations of Vibrio spp. bacteria in a well-studied lagoonal estuary. Water samples collected from the Neuse River Estuary in eastern North Carolina from 2004–2014 (with additional follow-up samples from Fall of 2018) were analyzed to determine Vibrio spp. concentrations, as well as the concentrations of inorganic and organic nutrients, fecal indicator bacteria, phytoplankton biomass, and a wide range of other physio-chemical estuarine parameters. A significant increase in Vibrio spp. was observed to occur in the estuary over the examined period. Strikingly, over this long duration study period, this statistically significant increase in total culturable Vibrio spp. concentrations does not appear to be correlated with changes in salinity, temperature, or dissolved oxygen, the three most commonly cited influential factors that predict estuarine Vibrio spp. abundance. Furthermore, shorter term (~3 years) data on specific Vibrio species (V. vulnificus and V. parahaemolyticus)show that while Vibrio spp. are increasing overall as a genus, the numbers of some key potentially pathogenic species are decreasing as a part of the total population, further supporting the concept that quantification of the entire genus is not a worthwhile use of resources toward predicting levels of specific potentially pathogenic species of public health concern. The significant increase in this concentration of Vibrio spp. in the studied estuary appears to be related to nitrogen and carbon in the system, indicating a continued need for further research.

Highlights

Bacteria in the genus Vibrio exhibit a great deal of variation, both phenotypically and genotypically
Factors driving the health of this important estuarine ecosystem are changing making an understanding of the dynamics of bacterial populations important to study
This continuous monitoring effort revealed that Vibrio spp. concentrations appear to be increasing in the Neuse River Estuary (NRE) in eastern North Carolina (NC) (Fig 3)

Summary

Introduction

Bacteria in the genus Vibrio exhibit a great deal of variation, both phenotypically and genotypically. Most bacteria of the Vibrio genus are important aquatic ecosystem members that can be found in fresh, brackish, and marine waters, often with strong, species-specific salinity preferences [1,2,3]. Vibrio are fast-growing, with some species capable of doubling in less than ten minutes, and are able to take rapid advantage of pulses of nutrient or shifts in meteorological conditions [4,5]. Vibrio spp. are ubiquitous across aquatic environments and over. Support for this project came from the UNC Research Opportunities Initiative, and from funds from the Office of the Vice Chancellor for Research at UNC Chapel Hill. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

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