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Title: Improved estimation of f-ratio in natural phytoplankton assemblages
Authors: Elskens, M ×
Goeyens, Leo
Dehairs, F
Rees, A
Joint, I
Baeyens, W #
Issue Date: 1999
Publisher: Pergamon-elsevier science ltd
Series Title: Deep-sea research part i-oceanographic research papers vol:46 issue:10 pages:1793-1808
Abstract: Statistical properties in non-linear regression models of f-ratio versus nitrate relationships were investigated using a case study conducted at the European continental margin (Project OMEX). Although the OMEX data fit within the family of empirical models introduced by Platt and Harrison (1985, Nature 318, 55-58), it is shown that the discrepancy between experimental and fitted values is larger than expected, assuming that the data are accurate. Since the ambient ammonium concentration plays a leading role in regulating new production, the present analysis was extended to include explicitly the effect of ammonium on f-ratio versus nitrate plots. Experimental results based on controlled ammonium additions were used to express the f-ratio as a function of both nitrate concentration and ammonium inhibition, i.e, f*((NO3,alpha)).I-(NH4,I-beta). The estimation behaviour of the data set/model combination was analysed by testing the appropriateness of various model functions for f* and I. The best fit was obtained with a sigmoid curve, for which mean values of the random fluctuation are almost commensurate with the estimated uncertainty of the measurements with natural phytoplankton assemblages. Precision of the f-ratio estimates was further assessed from contour diagrams of constant likelihood. The significance, validity limits of the estimated parameters, and the relevance of the proposed model as a predictive tool are discussed. Overall, this empirically determined model results in improved precision off-ratio estimations. (C) 1999 Elsevier Science Ltd. All rights reserved.
URI: 
ISSN: 0967-0637
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Centre for Food and Microbial Technology
× corresponding author
# (joint) last author

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