NCCOS scientists and their partners have identified a link between inter-annual patterns of precipitation and air temperature and fecal coliform levels inshellfish harvest waters in Maryland's portion of the Chesapeake Bay.

Drawing on 34 years of monitoring data (1979 -2013) from the Maryland Department of the Environment, the team found that fecal coliform tended to be higher in years when the bulk of precipitation occurred throughout the summer and fall.The study also revealed an intra-annual delay in timing between elevatedprecipitation and bacterial levels. Fecal coliform often peaked in late fall and winter, with precipitation peaking in summer and early fall.Additionally, continental-scale sea level pressure analysis showed an association between storm-generating atmospheric patterns and very high fecal coliform years.

Patterns of sea level pressure and precipitation corresponded to years with high fecal bacteria in shellfish harvest waters, with some delays in timing between rainfall and elevated bacterial levels. Credit: Integration and Application Network, University of Maryland Center for Environmental Science.

While natural resource managers have worked to reduce bacterial levels in the Chesapeake Bay, most rivers in the region contain areas where shellfish harvest is restricted due to excessive fecal bacteria. Understanding thelinksbetween these bacteria and climate variables will inform decisions about restricting access to shellfish harvest beds. The results of this study will also be useful for management of shellfish aquaculture, a growing industry in Maryland waters.

This study was in done in collaboration with the Maryland Department of the Environment and the University of Maryland Center for Environmental Science and was recently published inWater Research.

For more information, contact AK.Leight@noaa.gov.