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ENHANCEMENT OF NET PRIMARY PRODUCTIVITY BY HERBIVORE GRAZING IN AQUATIC LABORATORY MICROCOSMS 1
Author(s) -
Cooper David C.
Publication year - 1973
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.1973.18.1.0031
Subject(s) - microcosm , herbivore , grazing , standing crop , productivity , biomass (ecology) , primary production , autotroph , ecology , biology , salmo , population , agronomy , environmental science , ecosystem , fish <actinopterygii> , fishery , genetics , demography , sociology , bacteria , economics , macroeconomics
The role of herbivore grazing intensity as a factor affecting net primary productivity was investigated by introducing varying biomasses of a starved herbivore ( Notropis spilopterus ) into replicate autotrophic microcosms. After 20 days, the enhancement of net primary productivity in the experimental microcosms was directly related to herbivore biomass up to a certain density and inversely related above this. The relationship approximates the first derivative of a sigmoid population growth model. Enhancement of primary production under these experimental conditions appears to be due to reductions of standing crop and increased turnover rates of producer populations. The results suggest that these responses were independent of increased nutrient regeneration rates brought about by grazing.