Relationships between Nannoplankton and Lake Trophic Status

The hypotheses that with increasing eutrophication (1) nannoplankton biomass increases and (2) the relative proportion (percent) of nannoplankton biomass decreases were tested with data from Lake Memphremagog, a lake exhibiting a nutrient gradient, and on a more general scale using published data from a number of lakes. Both hypotheses were supported within and among lakes if trophic status was defined by total algal biomass. This was also generally true if total phosphorus (TP) was used as an alternative measure of trophy, although percent nannoplankton biomass showed no relationship to TP among lakes. Empirical relationships that allow a first prediction of total nannoplankton biomass from total algal biomass or TP were calculated. The data suggest that among lakes, net plankton will show a more variable relationship with TP than nannoplankton.