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- Title
EVALUATION OF COMPETITIVE ABILITY OF <em>STAURASTRUM LUETKEMUELLERII</em> (CHLOROPHYCEAE) AND <em>MICROCYSTIS AERUGINOSA</em> (CYANOPHYCEAE) UNDER P LIMITATION.
- Authors
Olsen, Yngvar
- Abstract
The desmid Staurastrum luetkemuellerii Donat et Ruttner and the cyanobacterium Microcystis aeruginosa Kütz showed pronounced differences in chemical composition and ability to maintain P fluxes. The cellular P:C ratio (Q[SUBp]) and the surplus P:C ratio (Q[SUBse]) were higher in M. aeruginosa, indicating a lower yield of biomass C per unit of P. The subsistence quota (Q[SUB0]) was 1.85 μg P mg C[SUP-1] in S. luetkemuellerii and 6.09 μg P mg C[SUP-1] in M. aeuginosa, whereas the respective Q[SUBp] of P satustores could support four divisions in S. luetkemuellerii and three divisions in M. aeruginosa, which suggests that the former exhibited highest storage capacity (Q/Q[SUB0]) M. aeruginosa showed a ten-fold higher activity of alkaline phosphatase than S. luetkemullerii when P starved. The optimum N:P ratio (by weight) was 5 in S, luetkemuellerii and 7 in M. aeruginosa. The initial uptake of P[SUB1] pulses in the organisms was no inhibited by rapid (<1 h) internal feedback mechanism and the short term uptake rate could be expressed solely as a function of ambient P[SUB0]. The maximum cellular C-based uptake rate (V[SUBm]) in P starved M. aeruginosa was up to 50 times higher than that of S. Iuetkemuellerii. It decreased with increasing growth rate (P status) in the former species and remained fairly constant in the latter. The corresponding cellular P-based value (U[SUBm] = V[SUBm]/Q[SUBp]) decreased with growth rate in both spcies and was about 10 times higher in P starved M. aeruginosa than in S. Iuetkemuellerii. The average half saturation constant for uptake (K[SUBm]) was equal for both species (22 μg P L-1) and varied with the P status. S. luetkemuellerii exhibited shifts in the uptake rate of P[SUB1] that were characterized by increased affinity (U[SUBm]/K[SUBm]) at low P. concentrations. The species thus was sell adopted to uptake at low ambient P[SUBi] uptake under steady state and transient conditions when the growth rate was lower than 0.75 d[SUP-1]. Moreover, M. aeruginosa was favored by pulsed addtion of P[SUBi]. M. aeruginosa released P[SUBi] at a higher rate than S. Iuetemuellerii. Leakage of P[SUBi] from the cells caused C-shaped μ vs P[SUBi] curves. Therefore, no unique K[SUBi] for growth could be estimeated. The maximum growth rate (μ[SUBm]) (23°C) was 0.94 d[SUP-1] for S. Iuetkemuellerii and 0.81 d[SUP-1] for m. aeroginosa. The steady state concentration of P[SUBi] (P[SUP4]) was lower n M. aeruginosa than in S. Iuetkemuellerii at medium growth rates. The concentration of P[SUBi] at which the uptake and release of P[SUBi] was equl (P) was, however, lower in S. Iuetkemuellerii.
- Subjects
RUGOSA; CHROOCOCCACEAE; MICROCYSTIS aeruginosa; GREEN algae; ALGAL growth; COMPETITION (Biology)
- Publication
Journal of Phycology, 1989, Vol 25, Issue 3, p486
- ISSN
0022-3646
- Publication type
Article
- DOI
10.1111/j.1529-8817.1989.tb00254.x