U.S. Environmental Protection Agency


Date of this Version



[Washington, D.C.] : Office of Research and Monitoring, Environmental Protection Agency, February 1972. Water pollution control research series ; project number 16010 DON.


U. S. government work.


A small Florida lake has been receiving a regimen of nutrient addition equivalent to 500 mg/m3-yr N and 43 mg/m3-yr P since 1967. Data has been accumulated through 1969. The effect on the lacustrine ecosystem of various biogenes includes production by primary producers, species diversity of plankton and certain production estimates at the secondary trophic level using natural populations of planktivorous fish. Plankton production using isotopic carbon is ca. 58 grms/m2-yr; Species diversity is slowly changing to a mixed chlorophycean and yellow-green. Biomass of benthic green filamentous types has increased slightly. Nutrient addition has had little influence on zooplankton production.

Related studies on 53 other regional lakes have been done using a multi-dimensional hybrid concept as defined by several trophic state indicators. This trophic state index has provided a means for ranking the lakes on an arbitrary scale. Cluster analysis utilizing pertinent characteristics resulted in classification of other lakes.

Land use patterns and population characteristics were determined photographically and N and P budgets estimated, Using multiple regression and canonical analysis, several significant relationships were found between lake trophic state, lake basin, land use, and population characteristics. In general, trophic state of lakes can be expressed as a simple relationship incorporating N and P influx rates.

This report was submitted in fulfillment of Grant #16010DON under the (partial) sponsorship of the Water Quality Office, United States Environmental Protection Agency.