Nuclear DNA in the determination of weighing factors to estimate exergy from organisms biomass

The application of ecological exergy as a suitable system-oriented development indicator of ecosystems and the estimation proposals from biomass are revised. DNA contents (C-values) of several groups of organisms are figured, either determined by flow cytometry or taken from literature. The applicability of DNA contents for determination of weighing factors to estimate ecological exergy from the biomass of organisms, as proposed by [Marques, J.C., M.Â. Pardal, S.N. Neilsen, S.E. Jørgensen, 1997. Analysis of the properties of exergy and biodiversity along an estuarine gradient of eutrophication. Ecol. Model. 102: 155–167.], is discussed and putative values for these weighing factors (β) are presented. This proposal is discussed in theoretical and practical aspects, concerning reliability and eventual application in ecological ‘exergetic’ studies.