Spring 2007 Update: Fall Chlorophyll Distribution
A general pattern is evident where chlorophyll concentration is greatest in continental shelf waters, intermediate over the deeper slope water, and lowest in the vicinity of the Gulf Stream and Sargasso Sea (see upper map figure showing concentration of chlorophyll during October 2006 from Cape Hatteras to Nova Scotia). High levels of chlorophyll occur in the tidally mixed central areas of Georges Bank and Nantucket Shoals, and in the Middle Atlantic Bight estuaries and coastal waters enriched by estuarine plumes. The high chlorophyll values (3-8 mg m-3) in the nearshore northern Gulf of Maine indicate that fall bloom is underway during October. The same geographic range is used to illustrate how chlorophyll conditions during October 2006 compare with the average values for this month, where the average is computed from October data from 1997 through 2006 (see lower map figure showing ratio of chlorophyll concentration). The ratio of October 2006 chlorophyll to the 10-year October mean chlorophyll indicates that each of the four major subareas of the ecosystem have some areas above and below the climatological average for October. In the nearshore areas, the phytoplankton fall bloom usually starts in September and peaks during October. These recent data from October 2006 suggest that while the fall bloom is underway it is somewhat above the mean levels only in the nearshore GOM and nearshore waters off New Jersey.