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AMMONIUM, NITRATE, PHOSPHATE, AND INORGANIC CARBON UPTAKE IN AN OLIGOTROPHIC LAKE: SEASONAL VARIATIONS AMONG LIGHT RESPONSE VARIABLES 1
Author(s) -
Dodds Walter K.,
Priscu John C.
Publication year - 1989
Publication title -
journal of phycology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.85
H-Index - 127
eISSN - 1529-8817
pISSN - 0022-3646
DOI - 10.1111/j.0022-3646.1989.00699.x
Subject(s) - ammonium , nitrate , nutrient , photosynthesis , diel vertical migration , phosphate , total inorganic carbon , photosynthetically active radiation , botany , environmental chemistry , biology , carbon dioxide , zoology , chemistry , ecology , organic chemistry , biochemistry
The dependence of substrate saturated uptake of 15 NH 4 + , 15 NO 3 − , 32 PO 4 3− , and 14 CO 2 on photosynthetic photon flux density (PPFD or photsynthetically active radiation, 400–700 nm) was characterized seasonally in oligotrophic Flathead Lake, Montana. PO 4 3− uptake was not dependent upon PPFD at any time of the year, whereas NH 4 + , NO 3 − , and CO 2 uptake were consistently dependent on PPFD over all seasons. Maximal rates of NH 4 + , NO 3 − and CO 2 uptake usually occurred near 40% of surface PPFD, which corresponded to about 5 m in the lake; inhibition was evident at PPFD levels greater than 40%. NH 4 + , NO 3 − and PO 4 3− were incorporated in the dark at measurable rates most of the year, whereas dark CO 2 uptake was always near 0 relative to light uptake. CO 2 and NO 3 − uptake were more strongly influenced by PPFD than was NH 4 3− uptake. The PPFD dependence of PO 4 3− , NH 4 + , NO 3 − and CO 2 uptake may affect algal growth and nutrient status by influencing the balance in diel and seasonal C:N:P uptake ratios.