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High long‐term nitrate uptake by oyster‐pond microalgae in the presence of high ammonium concentrations
Author(s) -
Collos Y.,
Maestrini S. Y.,
Robert J.M.
Publication year - 1989
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.1989.34.5.0957
Subject(s) - nitrate , ammonium , axenic , environmental chemistry , chemistry , nitrogen , biomass (ecology) , biology , botany , zoology , ecology , genetics , organic chemistry , bacteria
Natural assemblages and axenic cultures of oyster‐pond microalgae (dominated by pennate diatoms) were subjected to nutrient pulses in which the concentrations of ammonium and nitrate simulated the natural pulses to which these populations are regularly exposed. In natural populations, nitrate uptake (per unit of Chl a or particulate N) always presented a maximum at ammonium levels between 10 and 30 µ g‐atoms N liter ‘. Such maxima coincided either with the maximal ammonium uptake rate or with the start of a decrease in ammonium uptake. Nitrate uptake then decreased and went through a secondary maximum at lower ammonium levels. Although species succession could not be ruled out as a possible cause for these patterns, 48–69% of the variability in nitrate uptake could be explained by variations in the concentration of nitrate relative to the sum of nitrate and ammonium, corrected for biomass increases. In axenic cultures of three species of diatoms isolated from these environments, this percentage varied between 78 and 99%.