Unfortunately, no direct
measurements of N and P flux to the phytoplankton were made.
Berman (1997) showed evidence based on the concentration changes of epilimnetic
DIN and DON indicating that most of the N requirement for the
outgrowth of the A.ovalisporum bloom was derived from DON, either directly
or indirectly as NH3
+
after bacterial deamination of the organic N substrates. This
suggestion does not preclude some N fixation by the cyanobacteria, but posits that
in the case of the 1994 bloom, the capability to fix dissolved N2 did not serve as
a competitive advantage for A.ovalisporum.