The dominance of the above phytoplankton species in
most studied farms led to very low phytoplankton species
diversity, with an average value on all farms of
0.76 ± 0.25 bits cell1
, varying from 0.5 to 1.1 bits cell1
(Fig. 2). The highly unbalanced system favored irregular
blooms of some species, showing that the ponds present
low species number and low evenness. According to Paerl
(1988), blooms exist as massive accumulations of a single
or less often two coexisting species with densities of 104
–
106 cells mL1
, and the nuisance species account for as
much as 95–99% of the resident biomass. Smith (1985) suggested
that highly diverse algal communities are less likely
to collapse than blooms dominated by one species.
P