MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 495:77-90 (2014) - DOI: https://doi.org/10.3354/meps10559 Evidence for light-environment control of carbon isotope fractionation by benthic microalgal communities Kara R. Radabaugh*, Elon M. Malkin, David J. Hollander, Ernst B. Peebles University of South Florida, College of Marine Science, St. Petersburg, Florida 33701, USA *Corresponding author: kradabau@mail.usf.edu ABSTRACT: Assemblages of filamentous algae and diatoms were grown on glass plates suspended in the water column in Tampa Bay, Florida (USA). Carbon isotope ratios (δ13C) of the accumulated OM (OM) were analyzed to compare the effects of aqueous CO2 concentration, OM accumulation rate, algal type, and photosynthetically active radiation (PAR) on community-level carbon isotope fractionation between aqueous CO2 and organic carbon. Concentrations of nutrients, PAR, and colored dissolved OM exhibited spatiotemporal variation during 6 experiments conducted over 2 mo of variable rainfall and terrestrial runoff. Fractionation ranged from 6.8 to 13.7‰ and was positively correlated with PAR, resulting in higher δ13C values for OM in low-light conditions. Fractionation was lower and OM accumulation rates were higher during the 3 early experiments, which had high nutrient concentrations as a result of terrestrial runoff. OM accumulation rates and CO2 concentrations did not independently correlate with fractionation. The dominant factors influencing fractionation were PAR and spatial coverage by pennate diatoms, which together explained 56% of variability in fractionation. These results indicate that PAR significantly influences microalgal fractionation in estuaries, supporting the concept that the light environment may contribute to the widely observed phenomenon of higher δ13C values in benthic algae relative to phytoplankton. KEY WORDS: Photosynthetic fractionation · Benthic algae · Basal resource · Light attenuation · Estuary Full text in pdf format PreviousNextCite this article as: Radabaugh KR, Malkin EM, Hollander DJ, Peebles EB (2014) Evidence for light-environment control of carbon isotope fractionation by benthic microalgal communities. Mar Ecol Prog Ser 495:77-90. https://doi.org/10.3354/meps10559 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 495. Online publication date: January 09, 2014 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2014 Inter-Research.