Abstract
AB Aquatic Biology Contact the journal Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections AB 23:49-60 (2014) - DOI: https://doi.org/10.3354/ab00601 Supply- and demand-driven phosphate uptake and tissue phosphorus in temperate seaweeds E. J. Douglas, T. R. Haggitt, T. A. V. Rees* Leigh Marine Laboratory and Institute of Marine Science, University of Auckland, PO Box 349, Warkworth, New Zealand *Corresponding author: ta.rees@auckland.ac.nz ABSTRACT: High in situ rates of phosphate uptake should coincide with high tissue phosphorus content and/or high growth rate and be either supply-driven (largely controlled by the phosphate concentration in the surrounding seawater) or demand-driven (largely dictated by the maximum uptake rate, Vmax, and under the control of the organism). To test this hypothesis, 6 common New Zealand seaweed species (Cystophora torulosa, Melanthalia abscissa, Pterocladia lucida, Ulva intestinalis, Xiphophora chondrophylla and Zonaria turneriana) were used. We calculated in situ rates of phosphate uptake from the kinetic constants of uptake, monthly rates of uptake at a fixed phosphate concentration and seawater phosphate concentration, and compared these rates with monthly tissue phosphorus content. There were no significant differences in the half-saturation constant (Km) values for phosphate uptake by the 6 species. Vmax and affinity (Vmax/Km) were largely a function of the seaweed surface area:volume quotient. In the 5 species where there was a peak in tissue phosphorus levels, it occurred in July or September/October. Peaks in tissue phosphorus in M. abscissa, P. lucida, U. intestinalis and Z. turneriana coincided with, or occurred soon after, peaks in calculated in situ rates of phosphate uptake. Maximum rates of in situ phosphate uptake were demand-driven in all subtidal species and supply-driven in the only intertidal alga U. intestinalis. KEY WORDS: Phosphate uptake · Phosphorus · Seaweeds · Uptake kinetics Full text in pdf format PreviousNextCite this article as: Douglas EJ, Haggitt TR, Rees TAV (2014) Supply- and demand-driven phosphate uptake and tissue phosphorus in temperate seaweeds. Aquat Biol 23:49-60. https://doi.org/10.3354/ab00601 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AB Vol. 23, No. 1. Online publication date: December 02, 2014 Print ISSN: 1864-7782; Online ISSN: 1864-7790 Copyright © 2014 Inter-Research.
Highlights
Seaweeds require phosphorus for growth, as it is a major constituent of RNA and, is involved in protein synthesis (Sterner & Elser 2002)
Rates of phosphate uptake at an external concentration of 5 μM phosphate reached a peak in spring (September/October) for 4 species (Melanthalia abscissa, Pterocladia lucida, U. intestinalis and Zonaria turneriana) (Fig. 4)
Stronger patterns emerged with comparisons of calculated in situ rates of phosphate uptake (Fig. 5)
Summary
Seaweeds require phosphorus for growth, as it is a major constituent of RNA and, is involved in protein synthesis (Sterner & Elser 2002). It is a constituent of phospholipid, sugar phosphates and nucleotides such as ATP. The amount of phosphorus present in the tissues of a seaweed can change depending on the rates of input (rate of net uptake) and output (growth, reproduction and other loss of tissue). The balance between these 2 is the cellular phosphorus content of intact tissue.
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