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

Abstract

1. Seasonal dynamics of the exotic Daphnia lumholtzii and native macro‐zooplankton species were studied for 2 years in six inter‐connected lakes in Florida, U.S.A. The lakes ranged widely in pH, colour and trophic status, and were dominated by copepods. 2. All six lakes contained both D. lumholtzii and the native D. ambigua, but the two species did not overlap in time. D. ambigua was dominant in autumn–spring, coinciding with lower water temperature, higher transparency and lower nutrient and chlorophyll a (Chl a) concentrations than in summer, when D. lumholtzii was dominant. 3. Based on the field observations, temperature optima were 24 °C for D. ambigua and 29 °C for D. lumholtzii, suggesting that temperature plays a role in determining dominance among the daphnids of subtropical Florida lakes. 4. D. lumholtzii has not displaced native cladocerans but occupies a ‘vacant’ seasonal niche, unexploited due to the inability of native taxa to tolerate high temperature. Furthermore, D. lumholtzii did not significantly alter algal–zooplankton interactions. There was evidence of top–down control by grazing, but it was primarily attributable to the native taxa.

Crustacean zooplankton communities in 13 lakes of Yunnan-Guizhou plateau: Relationship between crustacean zooplankton biomass or size structure and trophic indicators after invasion by exotic fish

“…In the present study, there is no consistent correlation between chlorophyll a and cladoceran biomass or size structure. This suggests that there is little control of phytoplankton biomass by macrozooplankton, which is consistent with findings in subtropical lakes (Havens et al, 2000;Wang et al, 2007a). It also suggests that phytoplankton biomass in the 13 lakes was controlled by bottom-up, rather than top-down forces.…”

Crustacean zooplankton size structure in aquaculture lakes: is larger size structure always associated with higher grazing pressure?

“…Also, the ratio of zooplankton to phytoplankton biomass decreased with increasing total phosphorus. Havens et al (2000) generalized that subtropical lakes are usually dominated by copepods and large cladocerans are rare or absent in summer, and there is little control of phytoplankton by macro-zooplankton grazing. Our results provided evidence for the above generalization.…”

Daphnia lumholtzi Sars, 1885 (Cladocera: Daphniidae) invades Argentina

“…1A). Large defensive spines and pronounced success in reservoirs in North America have meant that this species has a negative effect on native ecosystems and fisheries (Swaffar and O'Brien, 1996;Havens et al, 2000). D. lumholtzi was first established in North America in 1983 in association with mass stocking of African Blue Tilapia Oreochromis aureus (Steindachner, 1864) or/and Nile perch Lates niloticus (Linnaeus, 1758) to Fairfield Reservoir, Texas (Sorensen and Sterner, 1992;Havel and Hebert, 1993).…”