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Kinetic examination of nitrogen release by zooplankters 1
Author(s) -
Gardner Wayne S.,
Scavia Donald
Publication year - 1981
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.1981.26.5.0801
Subject(s) - ammonium , daphnia pulex , daphnia magna , nitrogen , chemistry , reagent , zoology , nuclear chemistry , dry weight , nutrient , chromatography , environmental chemistry , biology , botany , daphnia , ecology , toxicity , organic chemistry , crustacean
Kinetics of nitrogen release by Daphnia magna (0.2–0.4 mg dry wt) and Daphnia pulex ( ca. 0.03 mg dry wt) were followed by measuring ammonium (plus primary amines) in water flowing past individual animals. Culture media water was pumped slowly (6 ml · h −1 ) through an incubation chamber (volume 0.05 ml) containing a daphnid and then either mixed with o‐phthalaldehyde reagent for continuous analysis of nitrogen compounds or passed into a sample loop of an ammonium analyzer for measurements of ammonium release at discrete intervals. Within the resolution of the technique (3 min), nutrient regeneration appeared continuous rather than pulsed. Highest rates of ammonium release, 44 nmol·(mg dry wt) −1 ·h −1 (SE = 5, N = 8), were typically observed immediately after the animals were removed from food. Regeneration rates for D. magna gradually decreased during the first hour to a mean steady state rate of 11 nmol·(mg dry wt) −1 ·h −1 (SE = 2, N = 8).