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Elevated CO2: Impact on diurnal patterns of photosynthesis in natural microbial ecosystemsAlgae, including blue-green algae (cyanobacteria), are the major source of fixed carbon in many aquatic ecosystems. Previous work has shown that photosynthetic carbon fixation is often enhanced in the presence of additional carbon dioxide (CO2). This study was undertaken to determine if this CO2 fertilization effect extended to microbial mats, and, if so, at what times during the day might the addition of CO2 affect carbon fixation. Four microbial mats from diverse environments were selected, including mats from a hypersaline pond (area 5, Exportadora de Sal, Mexico), the marine intertidal (Lyngbya, Laguna Ojo de Liebre, Mexico), an acidic hotspring (Cyanidium, Nymph Creek, Yellowstone National Park), and an acidic stream at ambient temperature (Zygogonium, Yellowstone National Park). Carbon fixation in the absence of additional CO2 essentially followed the rising and falling sunlight levels, except that during the middle of the day there was a short dip in carbon fixation rates. The addition of CO2 profoundly enhanced carbon fixation rates during the daylight hours, including during the midday dip. Therefore, it is unlikely that the midday dip was due to photoinhibition. Surprisingly, enhancement of carbon fixation was often greatest in the early morning or late afternoon, times when carbon fixation would be most likely to be light limited.
Document ID
19950062197
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Rothschild, L. J.
(NASAAmes Research Center Moffett Field, California, US, United States)
Date Acquired
August 16, 2013
Publication Date
November 1, 1994
Publication Information
Publication: Life sciences and space research 25 (3): Natural and artificial ecosystems; Meeting F4 of the COSPAR Plenary Meeting, 29th, Washington, DC, Aug. 28-Sep. 5, 1992 . A95-93759
Volume: 14
Issue: 11
ISSN: 0273-1177
Subject Category
Life Sciences (General)
Accession Number
95A93796
Distribution Limits
Public
Copyright
Other

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