VIBRIO AND PHYTOPLANKTON DYNAMICS DURING THE SUMMER OF 2004 IN A EUTROPHYING ESTUARY

Abstract

Abstract. Bacterioplankton response to eutrophication is a critical part of the transition from phytoplankton blooms to bottom-water hypoxia in estuaries. This topic is of particular concern when endemic bacterial populations, such as Vibrio sp., may pose a health risk to local human populations using estuaries for recreation and food. The purpose of this study was to observe the dynamics of both Vibrio and phytoplankton in the Neuse River Estuary (NRE) in North Carolina, USA, during the summer of 2004. Vibrio concentrations, particle suspension characteristics, and chlorophyll a were measured in surface water collected at a series of stations along the estuarine gradient. Consistent with previous studies, a strong positive relationship between Vibrio concentration and salinity was found. Both Vibrio sp. and phytoplankton concentrations increased moving downstream, but beyond the salt front, phytoplankton declined while Vibrio sp. concentrations continued to increase. In surface waters, a large portion of suspensions was comprised of phytoplankton cells. The fraction of Vibrio cells attached to phytoplankton increased with phytoplankton concentration and decreased with increasing salinity. These observations of Vibrio dynamics in the NRE provide evidence that populations interact with phytoplankton populations in surface waters. This information may prove critical for models of estuarine bacterial dynamics in response to eutrophication.

Occurrence and seasonality of Vibrio aestuarianus in sediment and Crassostrea gigas haemolymph at two oyster farms in France

“…A positive correlation between Vibrio spp. and seasonal salinity has been shown by several authors (Hsieh et al 2004, Hsieh et al 2008, although other authors have found temperature to be a more important factor (Pfeffer et al 2003). For example, with V. parahaemolyticus, Parveen et al (2008) found a significant relationship between salinity and counts of this bacterium, while other studies did not (Ristori et al 2007).…”

Eos, Transactions, American Geophysical Union Volume 88, Number 8, 20 February 2007

“…Previous observations in the NRE support the possibility that a signifi cant portion of Vibrio (~30%) are attached to particles and that attachment increases when environmental conditions are unfavorable for growth (i.e., low salinity) or particulate loads are high [Hsieh et al, 2007].…”

“…The high Vibrio concentrations coincident with these winds were far in excess of predictions based on salinity and temperature [Hsieh et al, 2007]. Vibrio concentrations for samples collected during high-turbidity periods (normalized turbidity units (NTU) > 10) were signifi cantly higher (698 CFU per 100 milliliters) than for low-turbidity samples (161 CFU per 100 milliliters).…”

“…For example, shellfi sh providers have confidence that oysters harvested during winter contain low concentrations of Vibrio, thus the adage that shellfi sh consumption is safer during months containing the letter R. Particle-bound Vibrio could fi nd their way into fi lter-feeding organisms during resuspension events. This contamination would render ineffective current regulations that restrict harvesting following rainfall, but [Hsieh et al, 2007].…”

Spatio-Temporal Variations in Pathogenic Bacteria in the Surface Sediments of the Zuari Estuary, Goa, India

“…The ratio of TOC/TN was low (8.71) at the mouth of the estuary, indicating contribution of phytoplankton which could be a possible reason for high abundance of VC, as Vibrio spp. are associated with plankton population 49 . The abundance of Shigella spp.…”