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Time‐course of inorganic nitrogen uptake and incorporation by natural populations of freshwater phytoplankton
Author(s) -
PRISCU JOHN C.
Publication year - 1987
Publication title -
freshwater biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.297
H-Index - 156
eISSN - 1365-2427
pISSN - 0046-5070
DOI - 10.1111/j.1365-2427.1987.tb01053.x
Subject(s) - incubation , phytoplankton , nutrient , eutrophication , nitrogen , incubation period , substrate (aquarium) , environmental chemistry , zoology , chemistry , biology , ecology , biochemistry , organic chemistry
SUMMARY. 1. Time‐course measurements of NH 4 + and NO 3 − uptake were made on the natural phytoplankton populations in a eutrophic lake at a time when these nutrients were at their lowest annual concentration. 2. Both NH 4 + and NO 3 − uptake was increased at least five‐fold during the first 5 min of incubation following near saturating pulses of these nutrients. 3. Elevated uptake was also observed following low level (∼2μg N 1 −1 ) pulses of NH 4 + and NO 3 − , but substrate depletion during the first hour of incubation may have been partially responsible for this apparent enhancement. 4. Incorporation of I5 N into TCA‐insoluble material (protein) following the saturating NH 4 + pulse was increased less than total cellular 15 N uptake, whereas no elevation of 15 N incorporation into protein was observed following a saturating NO 3 − pulse. 5. The percentage of I5 N incorporated into protein, with respect to total cellular uptake, was ∼32% and ∼12% for NH 4 + and NO 3 − , respectively, following 5 h of incubation.