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Microenvironments and microscale productivity of cyanobacterial desert crusts

Journal of Phycology

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Abstract

We used microsensors to characterize physicochemical microenvironments and photosynthesis occurring immediately after water saturation in two desert soil crusts from southeastern Utah, which were formed by the cyanobacteria Microcoleus vaginatus Gomont, Nostoc spp., and Scytonema sp. The light fields within the crusts presented steep vertical gradients in magnitude and spectral composition. Near-surface light-trapping zones were formed due to the scattering nature of the sand particles, but strong light attenuation resulted in euphotic zones only ca. 1 mm deep, which were progressively enriched in longer wavelengths with depth. Rates of gross photosynthesis (3.4a??9.4 mmol O2A?ma??2A?ha??1) and dark respiration (0.81a??3.1 mmol Oa??2A?ma??2A?ha??1) occurring within 1 to several mm from the surface were high enough to drive the formation of marked oxygen microenvironments that ranged from oxygen supersaturation to anoxia. The photosynthetic activity also resulted in localized pH values in excess of 10, 2a??3 units above the soil pH. Differences in metabolic parameters and community structure between two types of crusts were consistent with a successional pattern, which could be partially explained on the basis of the microenvironments. We discuss the significance of high metabolic rates and the formation of microenvironments for the ecology of desert crusts, as well as the advantages and limitations of microsensor-based methods for crust investigation.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Microenvironments and microscale productivity of cyanobacterial desert crusts
Series title:
Journal of Phycology
Volume
32
Issue:
5
Year Published:
1996
Language:
English
Contributing office(s):
Forest and Rangeland Ecosystem Science Center
Description:
p. 774-782
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
774
Last page:
782
Number of Pages:
9