Light dependence of phosphorus uptake by microorganisms in the subtropical North and South Pacific Ocean

Abstract

AME Aquatic Microbial Ecology Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials AME 67:225-238 (2012) - DOI: https://doi.org/10.3354/ame01593 Light dependence of phosphorus uptake by microorganisms in the subtropical North and South Pacific Ocean Solange Duhamel1,2,*, Karin M. Björkman1, David M. Karl1 1Department of Oceanography, Center for Microbial Oceanography: Research and Education (C-MORE) and School of Ocean & Earth Science & Technology (SOEST), University of Hawaii, 1000 Pope Road, Honolulu, Hawaii 96822, USA 2Present address: Lamont-Doherty Earth Observatory (LDEO), Division of Biology and Paleo Environment, Columbia University, PO Box 1000, 61 Route 9W, Palisades, New York 10964, USA *Email: sduhamel@ldeo.columbia.edu ABSTRACT: Light and dark phosphate (PO43−) uptake rates were investigated in the North Pacific Subtropical Gyre (NPSG) and along a coastal to open ocean transect in the South Pacific Ocean. PO43− uptake rates were consistently higher when incubated in the light, but the ratio of uptake in the light and dark (L:D) decreased with depth. In the NPSG, the L:D ratio of euphotic-layer integrated PO43− uptake was 1.58 ± 0.08 (±SE, n = 15 profiles), and the average L:D ratio was 1.60 ± 0.45 (±SE, n = 42) between 5 and 45 m and 1.25 ± 0.70 (±SE, n = 28) between 150 and 175 m. The L:D ratio was higher for the pigmented plankton-enriched size fractions (0.6 to 2 µm and >2 µm), but results were difficult to interpret at the oligotrophic stations where non-pigmented and pigmented plankton cell sizes overlapped. Group-specific measurements obtained using flow cytometric cell sorting demonstrated that Prochlorococcus PO43− uptake rates were higher when the samples were incubated under ambient light. Adenosine-5′-triphosphate (ATP) uptake by Prochlorococcus was also higher in the light for the uptake of both the terminal PO43− group ([γ‑33P]ATP) and adenine moiety ([2,8-3H]ATP). This could be the result of secondary uptake of PO43− and/or adenine after ATP cleavage by non-pigmented picoplankton. There was no significant difference in P-assimilation by non-pigmented picoplankton between light and dark incubated samples. Light dependence of phytoplankton PO43− uptake could thus influence the functioning of the microbial loop and the flows of matter and energy in marine environments by creating temporal patterns of resource utilization. KEY WORDS: Light · Phosphorus uptake · Flow cytometry cell sorting · Picoplankton · Oligotrophic gyre Full text in pdf format PreviousNextCite this article as: Duhamel S, Björkman KM, Karl DM (2012) Light dependence of phosphorus uptake by microorganisms in the subtropical North and South Pacific Ocean. Aquat Microb Ecol 67:225-238. https://doi.org/10.3354/ame01593 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AME Vol. 67, No. 3. Online publication date: November 02, 2012 Print ISSN: 0948-3055; Online ISSN: 1616-1564 Copyright © 2012 Inter-Research.