Data/hora: 08/06/2024 13:30:34

Provedor de dados: 	27	
País: 	Belgium	
Título: 	Improved estimation of f-ratio in natural phytoplankton assemblages	
Autores: 	Elskens, M.; Goeyens, L.; Dehairs, F.A.; Rees, A.; Joint, I.; Baeyens, J.	
Data: 	1999	
Ano: 	1999	
Resumo: 	Statistical properties in non-linear regression models of &lt;i&gt;f&lt;/i&gt;-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&amp;#x2013;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 &lt;i&gt;f&lt;/i&gt;-ratio versus nitrate plots. Experimental results based on controlled ammonium additions were used to express the &lt;i&gt;f&lt;/i&gt;-ratio as a function of both nitrate concentration and ammonium inhibition, i.e. &lt;i&gt;f&lt;/i&gt;&lt;sup&gt;*&lt;/sup&gt;&lt;sub&gt;(&lt;i&gt;NO&lt;/i&gt;3,&amp;#x3b1;)&lt;/sub&gt;.&lt;i&gt;I&lt;/i&gt;&lt;sub&gt;(&lt;i&gt;NH&lt;/i&gt;4,&amp;#x3b2;)&lt;/sub&gt;. The estimation behaviour of the data set/model combination was analysed by testing the appropriateness of various model functions for &lt;i&gt;f&lt;/i&gt;&lt;sup&gt;*&lt;/sup&gt; and &lt;i&gt;I&lt;/i&gt;. 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 &lt;i&gt;f&lt;/i&gt;-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 of &lt;i&gt;f&lt;/i&gt;-ratio estimations.	
Tipo: 	Info:eu-repo/semantics/article	
Idioma: 	Inglês	
Identificador: 	http://www.vliz.be/nl/open-marien-archief?module=ref&refid=10269	
Fonte: 	%3Ci%3EDeep-Sea+Res.%2C+Part+1%2C+Oceanogr.+Res.+Pap.+46%2810%29%3C%2Fi%3E%3A+1793-1808	
Fonte: 	info:eu-repo/semantics/restrictedAccess