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Diel fluctuations of DOC generated by algae in a piedmont stream 1
Author(s) -
Kaplan Louis A.,
Bott Thomas L.
Publication year - 1982
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.1982.27.6.1091
Subject(s) - diel vertical migration , periphyton , dissolved organic carbon , benthic zone , algae , sunset , environmental chemistry , microcosm , environmental science , chlorophyll a , chemistry , zoology , oceanography , hydrology (agriculture) , ecology , geology , biology , botany , physics , geotechnical engineering , astronomy
Diel fluctuations in dissolved organic carbon (DOC) were measured in White Clay Creek, a piedmont stream in SE Pennsylvania. DOC concentrations, measured on 16 days from late March to early June and on 2 days in early November, 1978 and 1979, showed rapid increases from predawn minima to late afternoon maxima and gradual decreases after sunset. Concentrations increased during a single day by as much as 40% of the daily minimum. These measurements were made during periods of constant discharge and were not related to volume of flow or changes in groundwater DOC concentrations. Laboratory and microcosm experiments suggested that benthic algae excreted most of the DOM and that bacterial uptake modified its concentration and composition. When the diel pulse was strongest, net algal DOC excretion accounted for 20% of the total DOC exported from the watershed that day. Additional data show that the 14 C method of measuring algal excretion is quantitatively and qualitatively inaccurate for periphyton incubated for 2–4 h.