text: The stratification index for a Shelf Break Front is an indication of how productive phytoplankton will be. When the stratification index is approximately 1.5, this produces a nutrient-rich environment for the growth of phytoplankton. Too much higher, and the stratification of the water column will not cause the upwellings of nutrients needed for the phytoplankton to prosper, too much lower, and the water will be too turbulent for the phytoplankton to use the nutrients available.  
  Stability of the front, in addition to nutrients, is a key to phytoplankton production. 
  An illustration of the stratification index for Narragansett Bay is shown here, with the average speeds estimated, using actual bathymetry for the bay, and an estimated  for silt, which composes much of the bays bottom.  Using the Stokes Spreadsheet, and some customization on the size of silt particles, I used a  = 0.0011.  More accurate speed measurements and detailed  values for the Bays bottom could yield a higher fidelity image.
  Notice the green color (a stratification index of approximately 1.5) along the edges of the Northern Bay and near some of the islands.  These areas are favorable to the formation of algal blooms in the Narraganset Bay habitat due to the stratification index being approximately 1.5.  Algae have been observed in high concentration in some of these areas, but not all of them.
  Using flow cytometry, results  have determined that the relative abundance of picophytoplankton (m), small nanophytoplankton (2 to 10 m) and large nanophytoplankton (10-20 m) are greatly affected by the stratification index of the water column. Cell diversity was greatest in the presence of moderate levels of stratification.
  If the turbulence is too high, their numbers remain stable or fall, but if there is no turbulence, their numbers do fall.  It is postulated that the nutrient-rich boundary layer around each phytoplankton cell is not exhausted, but renewed, by this moderate level of turbulence.