An evaluation of Secchi disk visibility for estimating plankton density in Fish ponds

Correlation coefficients between Secchi disk visibility (X) in fish ponds and concentrations of chlorophyll a and particulate organic matter were –0.79 (P< 0.01) and –0.83 (P< 0.01), respectively. Different observers may obtain different values for Secchi disk visibility and measurements by the same observer differ with the time of day. Nevertheless, Secchi disk visibility provides a suitable estimate of plankton density for management purposes in ponds were plankton is the primary source of turbidityResearch supported by Hatch Project Alabama 398 and by the Office of Water research and Technology of the Department of the Interior through the Water Resources Research Institute of Auburn, University under provisions of the Water Research Act of 1964.