The influence of the coagulant PAX-18 on Planktothrix agardhii bloom in a shallow eutrophic fishpond.

Abstract

For the first time in the Czech Republic, the PAX-18 coagulant has beenused to restore a eutrophic fishpond. The polyaluminium hydrochloridecoagulant was applied repeatedly to a shallow eutrophic fishpond inspring 2005. Two cylindrical plastic enclosures were used to isolateparts of the pond as untreated controls. Selected environmentalvariables were measured in situ. Water samples were analyzed regularlyfor nutrients, chlorophyll a concentration and phytoplankton abundanceand structure with special focus on Planktothrix agardhii. The PAX-18treatment led to a marked increase in the N/P ratio and changes in thestructure and abundance of phytoplankton in the fishpond and P. agardhiiblooms were eliminated in the fishpond. By contrast, P agardhiidominated the phytoplankton in the control enclosures, as it bad in thefishpond in 2004, prior to the PAX-18 treatment.