TY - JOUR
T1 - Direct and indirect effects of zooplankton on algal composition in in situ grazing experiments
AU - Kagami, Maiko
AU - Yoshida, Takehito
AU - Gurung, Tek Bahadur
AU - Urabe, Jotaro
N1 - Funding Information:
Acknowledgements We thank Jef Huisman and Sabine Floeder for reviewing the manuscript and providing comments. We are grateful to R. D. Gulati for comments. M. Nakanishi and the participants of the aquatic ecology seminar in CER, Kyoto University gave us general support. T. Koitabashi and T. Ueda provided field assistance. This study was supported by Grand-in Aid for Scientific Researches (A) no. 10308025 and for Creative Basic Research (09NP1501) from the Ministry of Education, Science, Sports and Culture of Japan, and partly supported by a research fellowship of the Japan Society for the Promotion of Science for Young Scientists.
PY - 2002
Y1 - 2002
N2 - To examine both direct and indirect effects of macrozooplankton on phytoplankton species in Lake Biwa, we conducted in situ grazer-gradient experiments under different nutrient levels in summer, when Daphnia galeata dominated, and in autumn, when Eodiaptomus japonicus dominated. The experiments revealed that grazing pressure on phytoplankton was highly dependent on zooplankton species composition. Smaller phytoplankton species such as Stephanodiscus carconensis were more grazed when D. galeata was abundant, whereas large colonial diatom species such as Aulacoseira granulata were preferentially grazed when E. japonicus dominated. In addition, indirect effect of macrozooplankton through nutrient regeneration was suggested, although the magnitude of nutrient regeneration effects seemed to differ between D. galeata and E. japonicus. Specifically, growth rates of Sphaerocystis schroeteri were stimulated more by E. japonicus than by D. galeata. Macrozooplankton also enhanced the growth rates of colonial cyanobacteria such as Microcystis incerta, probably through decreasing the density of microzooplankton grazers (ciliates and rotifers). The results suggest that the effects of large zooplankton on phytoplankton populations are species-specific and cannot be understood without consideration of changes in abundance of other components of plankton communities.
AB - To examine both direct and indirect effects of macrozooplankton on phytoplankton species in Lake Biwa, we conducted in situ grazer-gradient experiments under different nutrient levels in summer, when Daphnia galeata dominated, and in autumn, when Eodiaptomus japonicus dominated. The experiments revealed that grazing pressure on phytoplankton was highly dependent on zooplankton species composition. Smaller phytoplankton species such as Stephanodiscus carconensis were more grazed when D. galeata was abundant, whereas large colonial diatom species such as Aulacoseira granulata were preferentially grazed when E. japonicus dominated. In addition, indirect effect of macrozooplankton through nutrient regeneration was suggested, although the magnitude of nutrient regeneration effects seemed to differ between D. galeata and E. japonicus. Specifically, growth rates of Sphaerocystis schroeteri were stimulated more by E. japonicus than by D. galeata. Macrozooplankton also enhanced the growth rates of colonial cyanobacteria such as Microcystis incerta, probably through decreasing the density of microzooplankton grazers (ciliates and rotifers). The results suggest that the effects of large zooplankton on phytoplankton populations are species-specific and cannot be understood without consideration of changes in abundance of other components of plankton communities.
KW - Grazing
KW - Lake Biwa
KW - Nutrient regeneration
KW - Species-specific response
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U2 - 10.1007/s00442-002-1035-0
DO - 10.1007/s00442-002-1035-0
M3 - Article
AN - SCOPUS:0036933454
VL - 133
SP - 356
EP - 363
JO - Oecologia
JF - Oecologia
SN - 0029-8519
IS - 3
ER -