Zooplankton densities in a Hydrilla infested lake

Abstract

The number of individuals and species of zooplankton were sampled concurrently with Hydrilla biomass and water quality for one year in a small, eutrophic central Florida lake . Throughout the study, rotifer species and individuals dominated the zooplankton . The abundance of the zooplankton tended to remain high when Hydrilla biomass was at its seasonal low during late winter and early spring . When hydrilla growth increased in the late spring and summer months causing a decrease in total alkalinity, specific conductivity, water color, turbidity, orthophosphate and chlorophyll a concentrations ; the abundance of the zooplankton declined .

Dynamics of the exotic Daphnia lumholtzii and native macro‐zooplankton in a subtropical chain‐of‐lakes in Florida, U.S.A.

“…Therefore, temperature effects on growth rates of zooplankton or their prey may have been a causal factor. The short duration of biomass peaks could be the result of fish predation, adverse physiological effects of water temperature near 30°C, or a rapid build-up of Hydrilla and the associated release of inhibitory chemicals, as has been observed in other Florida lakes (Schmitz & Osborne, 1984). A decline in edible algae, protozoa and bacterioplankton may also have played a role.…”

“…Zooplankton dynamics in subtropical lakes have been studied intensively, primarily in the 1970s and 1980s, much of the work being performed in Florida, U.S.A., where there are over 2000 lakes of differing size, trophic status, acidity and other features (Fernald & Purdum, 1998). The resulting generalities on subtropical macro-zooplankton include: (1) maximal biomass occurs during spring and/or autumn, separated by a mid-summer minimum (Nordlie, 1976;Schmitz & Osborne, 1984); (2) copepods dominate, particularly in summer, when cladocerans are rare or absent (Nordlie, 1976); (3) large Daphnia are absent (Blancher, 1984;Elmore, Cowell & Vodopich, 1984); and (4) there is little control of phytoplankton by macro-zooplankton grazing (Crisman & Beaver, 1990).…”

Somatic mutation‐mediated evolution of herbicide resistance in the nonindigenous invasive plant hydrilla (Hydrilla verticillata)

“…Left unmanaged, this invasive plant can rapidly cover thousands of contiguous hectares (Fig. 2A), displacing native plant communities and causing significant damage to the ecosystems (Colle & Shireman 1980; Schmitz & Osborne 1984; van Dijk 1985; Schmitz et al . 1993; Bates & Smith 1994).…”