Figure 13.2 Population fluctuations in the algae of Lake Erie. The number of algal cells in the water has fluctuated widely over time. The populations of green algae and diatoms that compose the phytoplankton varied by several orders of magnitude on a scale of days, weeks, and months.

Data from C. C. Davis, Evidence for the eutrophication of Lake Erie from phytoplankton records, Limnology and Oceanography 9 (1964): 275–283.