The Lake Superior Biomass Size-Spectrum

We combined data from multiple sampling programs to describe the Lake Superior pelagic biomass size structure.  The data represented phytoplankton, zooplankton and prey-fish that spanned over 10 orders of magnitude in size and two time periods separated by five years.  The biomass size-spectrum was stable over the 5-year time frame.  The primary scaling or overall slope of the normalized biomass size-spectra (NBSS) for the combined years was -1.113.  The slope was consistent with a previous estimate for Lake Superior (-1.10) that was based on phytoplankton and zooplankton (Sprules and Munawar 1986).  Periodic dome structures within the overall biomass size-spectrum were fit to polynomial regressions.  The regressions described observed sub-domes that occurred within the classical taxonomic positions (algae, zooplankton, and fish).  This more restricted interpretation of periodic dome structure was aligned more closely with predator-prey size relationships that existed within the zooplankton (herbivorous, predacious) and fish (planktivorous, piscivorous) taxonomic positions.  Domes were spaced approximately every 3.78 Log₁₀ units along the axis and with a decreasing peak magnitude of -4.1 Log₁₀ units.  The relative position of the algal and herbivorous zooplankton domes predicted well the subsequent biomass domes for larger predatory zooplankton and planktivorous prey fish.