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Nutrient recycling by fish versus zooplankton grazing as drivers of the trophic cascadein alpine lakes
Author(s) -
Sarnelle Orlando,
Knapp Roland A.
Publication year - 2005
Publication title -
limnology and oceanography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 197
eISSN - 1939-5590
pISSN - 0024-3590
DOI - 10.4319/lo.2005.50.6.2032
Subject(s) - zooplankton , phytoplankton , trophic cascade , biomass (ecology) , trophic level , benthic zone , environmental science , daphnia , trophic state index , plankton , nutrient , ecology , benthos , food web , biology
In a multilake experiment, we found little effect of nutrient excretion by zooplanktivorous fish, but a large effect of herbivorous zooplankton, on phytoplankton biomass and phosphorus (P) limitation. Whole‐lake removal of fish from small alpine lakes resulted in little change in phytoplankton biomass or the intensity of P limitation during 1–6 postremoval years, over which herbivorous zooplankton did not change. In contrast, significant decreases in phytoplankton biomass and the intensity of phytoplankton P limitation were observed after Daphnia became reestablished. Fish removal also caused large increases in the biomass of benthic macroinvertebrates, but the timing of these increases suggested that P recycling by the benthos did not confound our attempt to measure the effects of P recycling by fish. Estimates of the amount of P recycled by fish and zooplankton and estimates of P demand by the phytoplankton also supported the conclusion that fish recycling was not a major source of P to the phytoplankton in these lakes. Relative to Daphnia grazing, fish recycling of P appears to be relatively unimportant as a driver of trophic cascades in these alpine lakes.