Wastewater Bacteria and Shellfish

Abstract

Extensive field and laboratory studies were conducted from 1986 to <br /><br />1989 to determine relationships between wastewater discharges and bacteria in <br /><br />shellfish. Dyed wastewater plume studies showed rapid decrease in recoverable <br /><br />bacteria in seawater. Weekly measurement of water column bacteria throughout <br /><br />the study area over a year-long period showed that waters met the standards for <br /><br />approved growing waters for shellfish. Nevertheless, some shellfish tissue samples <br /><br />exceeded market standards for total and fecal coliform bacteria. Thus, spatial <br /><br />deployments of oysters and mussels were used to evaluate potential sources of <br /><br />bacteria. Bacterial concentrations in shellfish showed poor correlation with periods <br /><br />of disinfection and non-disinfection of wastewater discharges. Bacteria in shellfish <br /><br />correlated with periods of storm water runoff. Laboratory studies determined the <br /><br />rate of uptake and depuration of wastewater bacteria by shellfish. Results showed <br /><br />that there must be cultureable bacteria in the water to retrieve cultureable bacteria <br /><br />in shellfish. Fecal Streptococcus appeared to be a better indicator than total and <br /><br />fecal coliform for correlating bacteria in shellfish with various sources of bacteria.