Abstract
Biological and environmental contrasts between aquatic and terrestrial
systems have hindered analyses of community and ecosystem structure across
Earth's diverse habitats. Ecological stoichiometry provides
an integrative approach for such analyses, as all organisms are composed of
the same major elements (C, N, P) whose balance affects production, nutrient
cycling, and food-web dynamics. Here we show both similarities
and differences in the C:N:P ratios of primary producers (autotrophs) and
invertebrate primary consumers (herbivores) across habitats. Terrestrial food
webs are built on an extremely nutrient-poor autotroph base with C:P and C:N
ratios higher than in lake particulate matter, although the N:P ratios are
nearly identical. Terrestrial herbivores (insects) and their freshwater counterparts
(zooplankton) are nutrient-rich and indistinguishable in C:N:P stoichiometry.
In both lakes and terrestrial systems, herbivores should have low growth efficiencies
(10-30%) when consuming autotrophs with typical carbon-to-nutrient ratios.
These stoichiometric constraints on herbivore growth appear to be qualitatively
similar and widespread in both environments.