A bloom of Karlodinium micrum continues to flourish in St. Leonard's Creek. A sample collected on July 1 showed concentrations of K. micrum were 58,000 cells/ml, similar to the later days of last week's "Black Tide" observations (see HAB News from June 24, 2003: "Black Tide on St. Leonards Creek, Calvert County.").

An update on data for the "Black Tide" measurements showed that chlorophyll (CHLA) measured last week in the surface layer by the Academy of Natural Sciences Estuarine Research Center taken in St. Leonard Creek at Mackall Cover (June 18th) was 6,645 ug/L. At approximately 1 foot (0.3m) below the surface CHLA measured 678 ug/L and from 1m to the bottom CHLA was less than or equal to 10 ug/L. By comparison, CHLA of 30 to 50 ug/L can often be considered as elevated levels in many systems.