Elizabeth Halliday


My research focuses on the fecal indicator bacteria that are used for monitoring whether beaches are safe for bathing. Elevated amounts of fecal indicator bacteria correspond to increased outcomes of gastrointestinal illness in bathers, and quite often the high bacteria counts detected through monitoring come from unknown sources of pollution.  The goals of my research are twofold: developing a faster method for monitoring harmful bacteria in recreational waters, as well as a better understanding of the environmental conditions that coincide with these bacterial water quality violations.  Working with biologist Rebecca Gast, we use the traditional culture-based methods that are the basis for current monitoring standards, as well as DNA-based methods to examine how amounts of fecal indicator bacteria in sand and water change over time, and to look for DNA signatures of pathogens and sewage. 

Recent research, including my own, has indicated that beach sands can contain abundant populations of the fecal indicator bacteria.  Understanding the sanitary condition of beach sands is one aspect of protecting beachgoers and maintaining healthy beaches.  Additionally, the interaction of tides with bacteria-rich beach sands can influence water quality measurements.  My results illustrate the complex relationship between fecal indicator bacteria and the environment at my field sites, and show how environmental parameters beyond rainfall can predict when bacterial violations are more likely to occur.

Ultimately, nobody wants to get sick from a day at the beach, nor unnecessarily close a beach when it’s actually safe for swimming! It has been a privilege working with communities on Cape Cod and in southern Maine that are concerned with improving their beach water quality, and to be supported in this work by the Coastal Ocean Institute.