Dealing with size-spectra: Some conceptual and mathematical problems
José M. Blanco, Fidel Echevarría, Carlos M. García

This contribution tries to depict and resolve some problems that arise when the researcher begins to study the size structure of the planktonic community. Data organization and representation, problems linked to choosing a nominal size of the class; extent, implications and meaning of the parameters arising from the representation and the influence of the sample size on the estimation of parameters are reviewed. We show how the representation of size in length or volume changes the form of the spectrum. Then, we give a method to avoid those differences, by calculating an optimum nominal size. The effect of correlation y/x vs x is analyzed in its implication on the random distribution of biomass in geometrical classes. Finally, we use the Montecarlo method to simulate the acquisition of data in a size-structured system, analyzing the effects of size of sample and size of class. This study shows an overestimation of spectrum parameters when the bulk of sample and size of classes are not in agreement.

Keywords: Biomass, abundance, size, models, spectra.
Contents of this volume Sci. Mar. 58(1-2) : 17-29 Back PDF
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