Evidence of interference of Asterionella formosa with the feeding of Bosmina longirostris: a field study in a south Andes lake

BALSEIRO, EG; QUEIMALIÑOS, CP; MODENUTTI, BE

HYDROBIOLOGIA

Kluwer

Lugar: Dordrecht; Año: 1991 vol. 224 p. 111 - 116

0018-8158

Intensive sampling of a small temperate lake of the Araucanian region (Argentina), revealed changes in the demography of Bosmina longirostris when the diatom Asterionellaformosa density increased (to 54 000 cells ml -1). Bosmina population behaviour in the field was consistent with the idea that large numbers of Asterionella caused its starvation. Individuals were actually colourless and fecundity dropped to zero, as was evident when Asterionella reached 99.4% of total phytoplankton biovolume. Since cyanophytes, as a whole, are scarce in these lakes, we propose that the flagellate/diatom ratio has a direct effect on cladoceran demography.