Phytoplankton responses to reduction and elimination of submerged vegetation by herbicides and grass carp in four Florida lakes

摘要: Abstract Four central Florida lakes were monitored for 3 years to determine the effects of macrophyte reduction and elimination by grass carp herbicide on phytoplankton populations. Clear Lake, in which stocked after a year baseline studies, had all macrophytes eliminated within 14 months. The density increased significantly from an initial 24-month mean 165 000 cells 1 −1 level 787 900 third year. In Little Lake Fairview, with both first study, vegetation was not until 34th month. Phytoplankton 64 200 370 Orienta, year, 6 abundance did change over course study (mean: 2 700 ). Mann treated alone data collection. Submerged reduced second but near biomass levels Year 3, Nitella sp. replacing Hydrilla verticillata (L.f.) Royle as dominant macrophyte. No significant yearly changes noted this lake. Orienta only lake number species collected differed between years. Cyanophytes (notably Anacystis, Microcystis Anabaena ) diatom, Fragilaria sp., predominated removed. Most observed direction apparent trophic state. Major shifts assemblage (e.g., Shannon diversity indices abundance) coincided periods maximal fluctuation vegetation. Reversals these tendencies during prolonged stable high low macrophute biomass.