Initial conditions mediate the interaction between Daphnia and bloom-forming cyanobacteria

Title
Initial conditions mediate the interaction between Daphnia and bloom-forming cyanobacteria
Publication Type
Journal Article
Year of Publication
2007
Authors

Sarnelle O

Journal
Limnology and Oceanography
Volume
52
Pagination
2120-2127
ISBN Number
0024-3590
Keywords

toxic cyanobacteria, eutrophic lake, Dapnhia, microcystis-aeruginosa, body-size, Zooplankton, water, biomass, phytoplankton, chlorophyll, phosphorus, mesocosm, freshwater, California, USA, 4m3

Abstract
To assess whether Daphnia populations in eutrophic lakes can increase when bloom-forming cyanobacteria dominate the phytoplankton assemblage and whether such an increase can result in strong suppression of phytoplankton biomass, I created contrasting initial conditions ( high Daphnia pulicaria, low cyanobacteria vs. low D. pulicaria, high cyanobacteria) via fish manipulation in large enclosures, then removed fish from some enclosures and subsequently monitored zooplankton and phytoplankton abundance for 48 days. After being released from fish predation, D. pulicaria was apparently able to reduce cyanobacteria and total phytoplankton biomass to very low levels despite the fact that the phytoplankton assemblage was initially composed of about 90% Microcystis aeruginosa, a species that has inhibited Daphnia growth and reproduction in many laboratory studies. Thus, it appears possible for Daphnia to graze down an established bloom of cyanobacteria. In contrast, in enclosures where fish were never present, M. aeruginosa was eventually able to increase from low levels despite initially high D. pulicaria biomass. As a result, the apparent effect of D. pulicaria on M. aeruginosa at the end of the experiment was very different across enclosures with different initial conditions.
Date of Published
Sep
Accession Number
WOS:000249416200032
Type of Article
Article
Alternate Journal
Limnol. Oceanogr.