Monster Seminar JAM - Environmental Pathogens in Ocean and Reservoirs
Dr. Erin Lipp, College of Public Health, Environmental Health Science, University of Georgia
Oceanic and coastal waters are known to harbor and transport microorganisms that cause disease in humans and other animals. While certain pathogenic microorganisms, including Vibrio spp., occur naturally in marine and estuarine waters, anthropogenic contaminants including enteric bacteria, protozoa and viruses may be introduced to coastal waters as sewage pollution. Despite the relatively unfavorable environment, these introduced organisms may survive for prolonged periods in the marine environment; and, it remains unclear how human pathogenic microbes interact in the complex estuarine environment and how those interactions ultimately affect their fate. We are exploring the role of plankton as a defined niche for a suite of microbial pathogens, both native and sewage-associated. We hypothesize that the high level of surface area represented by plankton would present a natural zone for microbial accumulation, in general, and that the specific composition of the plankton community would influence population dynamics in Vibrio spp. in particular. We examined the interactions between plankton, Vibrio spp., human enteric viruses and traditional fecal indicator bacteria in estuaries of coastal Georgia. Consistent with previous findings, Vibrio spp. were highly concentrated in the plankton fractions relative to the water column. Vibrio concentrations were also positively associated with copepod abundance in the small plankton fraction, when temperature and salinity were controlled. Both enterococci and fecal coliform bacteria were also found in higher concentrations in plankton fractions but varied in magnitude of enrichment over the study period; however, plankton-associated enterococci contributed up to 95% of the total enterococci load during summer months. Additionally, the human enteric noroviruses were found at their highest concentrations in the plankton, at up to 1014 genomes g-1. While this project started with the aim of expanding our understanding of the known relationship between Vibrio spp. and plankton our results suggest that microbial association among these phytoplankton and zooplankton groups may be a general phenomenon. It also suggests that plankton may provide critical refuge for many enteric microbes in an estuarine setting and thus enhance persistence and increase chances for human exposure.
Date and Time:
April 22, 2010,
11:00 am - 12:00 pm