Surfing the Biomass Size Spectrum: Some Remarks on History, Theory, and Application

Following upon their prior Coulter Counter observations on the size distributions of small particles in the ocean, RW Sheldon and colleagues published a seminal paper in 1972 in which they proposed as a first approximation that concentrations of marine particles in logarithmic size intervals “from bacteria to whales” were roughly equal.  This concept was quickly expanded both empirically and theoretically by a small group of researchers, and before long the biomass size spectrum caught the attention of a much broader diversity of scholars.  The underlying theory describes a community in which body size increases with trophic level, predators consume prey smaller than themselves, and material flow up the size spectrum is modelled by size-dependent ecological and physiological processes.  We will briefly review the development and application of the size spectrum and focus on some more problematic aspects of the theory including what it means when the structure of a community does not fit size spectrum predictions; whether the normalized size spectrum is best described by a linear or non-linear model and how this affects predictions of productivity in parts of the food web; and the importance of spatial, temporal and biological scales in applications of size spectrum theory.