Particle Size Spectra in Ecology

Abstract

The use of size distributions as descriptors of ecosystems goes back at least to Elton (1927), although quantitative applications have appeared only during the past decade. Elton noted that there was a characteristic difference between terrestrial and aquatic ecosystems; on land the organisms in the lower trophic levels tend to be larger than the organisms which feed on them (e.g. trees, giraffes, tigers), while in the sea the reverse is true (phytoplankton, zooplankton, fish). The value of this observation was dramatically emphasized by the advent of automated particle size measurement devices and their use in marine biology, which occurred in the 1960’s (Sheldon and Parsons 1967). A Coulter counter was used on the 1970 circumnavigation of the western hemisphere by the Canadian research vessel Hudson and this provided the first opportunity to compare particle size distributions from widely distributed pelagic marine environments, including both polar regions and the tropical waters of the Atlantic and Pacific oceans (Sheldon et al. 1972). This work greatly extended Elton’s observation by showing that there are also patterns in the size distributions from temperate and polar regions which are characteristically different from those found in tropical waters.