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Limnetic Herbivory: Effects on Phytoplankton Populations and Primary Production
Author(s) -
Bergquist A. M.,
Carpenter S. R.
Publication year - 1986
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.2307/1938691
Subject(s) - zooplankton , phytoplankton , nutrient , biomass (ecology) , limnetic zone , biology , algae , ecology , chlorophyll a , productivity , grazing , population , ecosystem , botany , littoral zone , demography , macroeconomics , sociology , economics
Population—level and ecosystem—level responses of phytoplankton to grazing by zooplankton were determined in nutrient—enriched and unenriched enclosures in Peter Lake, Michigan. Species—specific net growth rates were determined, and chlorophyll a, primary production (PPR), and alkaline phosphatase activity (APA) were determined for each of three size categories of phytoplankton: <22 μm, 22—75 μm, >75μm. Thirteen of 16 dominant algal taxa were nutrient limited. Zooplankton reduced APA, an indicator of nutrient deficiency. Growth rates of grazed, nutrient—limited algae (< 30 μm) increased at low levels of zooplankton μμm) nutrient—limited algae increased or did not change as zooplankton biomass increased. These species—specific responses resulted in four— to fivefold changes in chlorophyll concentration and PPR. Overall, the stimulatory effect of nutrient regeneration by zooplankton overrode losses due to grazing, and caused net increases in phytoplankton biomass and productivity.