Biomass of a trophic level increases with maximum body size, but less than proportionally

A recent paper by Enquist and colleagues1 took a very important step in predicting the ecosystemic effects of species losses on a global scale. Using Metabolic Scaling Theory (MST), they concluded that large-sized species contribute disproportionately to several ecosystem functions. One of their key predictions is that total biomass of animals in a trophic level (MTot, using their notation) should increase more than proportionally with its maximum body size (mmax), following the relationship MTot {propto} mmax5/4. Here I argue that this superlinear scaling results from an incorrect representation of the individual size distribution and that the exponent should be 1/4, implying a sublinear scaling. The same reasoning applies to total energy flux or metabolism BTot, which should be invariant to maximum size according to the energetic equivalence and perfect compensatory responses entailed by MST.