Abstract
1. Increased water motion is expected to reduce boundary layer diffusion resistance of autotrophs, thereby enabling greater isotopic discrimination against 13C such that lower δ13C values (ratio of 13C : 12C) should ensue. A field test of this hypothesis was undertaken by sampling benthic algae in streams of differing current speed.2. Contrary to the expected negative relationship between δ13C and water motion, filamentous benthic algae were found to exhibit higher δ13C values in rapid water.3. Under conditions of low current in the streams studied, concentrations of dissolved organic carbon as measured by water colour are elevated through the microbial decomposition of largely terrestrial organic matter. Photoassimilation of this respired carbon by benthic filamentous algae generates 13C‐depletion and lower δ13C values, and appears to be substantial enough in the streams used in the present study to override the competing influence of water motion on boundary layer thickness.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
