PAC

PAC is an abbreviation for percent area covered and is a measure of the percentage of the bottom area of a waterbody with aquatic macrophytes growing on, or over it. Aquatic scientists use PAC to assess the abundance and importance of aquatic plants in a waterbody.

Waterbodies in the Florida LAKEWATCH database have PAC values ranging from 0 to 100%. PAC values are linked with the biological productivity (trophic state) of waterbodies:

In the least productive (oligotrophic) waterbodies, PAC values are usually low. In rare cases where they are high (occasionally reaching 100%), it is usually because a thin layer of small plants such as chara (a macroalga) is growing along the bottom.
In moderately productive (mesotrophic) and highly productive (eutrophic) waterbodies, PAC values are generally greater than those measured in oligotrophic waterbodies, and the average plant biomass is also greater.
In extremely productive (hypereutrophic) waterbodies dominated by planktonic algae, PAC values are often less than 25%. In Florida, however, many hypereutrophic waterbodies contain mostly aquatic macrophytes, not algae. In these cases, PAC values often tend to be greater than 75%.

The information on this page was derived in part from the following publication of
Florida Lakewatch of the University of Florida Department of Fisheries and Aquatic Sciences.
This booklet may be downloaded in its entirety as a PDF file by clicking here.
Scroll down till you see the Circular 101 icon.

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A collaboration of the Center for Aquatic and Invasive Plants, University of Florida, and the Invasive Plant Management Section of the Florida Fish and Wildlife Conservation Commission.