Journal of the Marine Biological Association of the United Kingdom

Research Article

The Redfield Ratio and Phytoplankton Growth Rate

P. Tetta1, M. R. Droopa1 and S. I. Heaneya2

a1 Scottish Marine Biological Association, Dunstaffhage Marine Research Laboratory, P.O. Box 3, Oban, Argyll PA34 4AD

a2 Freshwater Biological Association, The Ferry House, Ambleside, Cumbria

Goldman, McCarthy & Peavey (1979b) argued that growth rates of phyto-plankton in apparently oligotrophic ocean waters may near maximal. Their hypothesis was succinctly restated by Goldman (1980): ‘…the chemical composition of phytoplankton is extremely variable under exacting laboratory conditions of nutrient limitation and approaches the ‘Redfield’ proportions (C:N:P of 106:16:1) when neither nitrogen nor phosphorus is limiting so that near maximal growth rates are attained. In marine surface waters the chemical composition of particular matter often is in the Redfield proportions, thus implying that natural phytoplankton growth rates may be close to maximal.’ We argue on theoretical, experimental and observational grounds that this implication may not necessarily be correct.