Phosphorus and nitrogen in coral reef sediments

The occurrence of P and N in the sediments has been investigated on Davies Reef in the central region of the Great Barrier Reef Complex. Concentrations of inorganic P and N in the water were typical of nutrient-depleted tropical surface water. Carbonate sediments were found to contain a uniform pool...

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Veröffentlicht in:Limnol. Oceanogr.; (United States) 1983-05, Vol.28 (3), p.465-476
Hauptverfasser: Entsch, Barrie, Boto, Kevin G., Sim, Robin G., Wellington, John T.
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Sprache:eng
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Zusammenfassung:The occurrence of P and N in the sediments has been investigated on Davies Reef in the central region of the Great Barrier Reef Complex. Concentrations of inorganic P and N in the water were typical of nutrient-depleted tropical surface water. Carbonate sediments were found to contain a uniform pool of P (300 ppm by wt), principally in the form of inorganic phosphate. The interstitial water of the surface layer of sediment contained micromolar concentrations of inorganic P and even higher concentrations of inorganic N, principally as ammonium. These nutrient concentrations should allow high rates of uptake of N and P by epilithic algae. Arsenate concentrations were considered too low to compete significantly with the uptake of available phosphate into algae. The presence of ammonium and soluble P was associated with anaerobic redox potentials in the sediments just below the surface. Soluble phosphorus was in equilibrium with a small, rapidly exchangeable fraction of the sedimentary pool of inorganic phosphate. Analyses of P in growing tips of Halimeda and corals (wich supply more than half of reef sediments) suggested that the skeletons provide a biological mechanism for the replenishment of at least some of the sedimentary pool. Ratios of C:N:P for a selection of benthic algae were used as a preliminary indicator of their N and P status.
ISSN:0024-3590
1939-5590
DOI:10.4319/lo.1983.28.3.0465