predictions about the effects of energy and materials on the ecology of organ-
isms and the roles of organisms on the fluxes and storage of energy and mater-
ials in ecological systems. The theoretical predictions provide baselines from
which to measure and understand the influences of additional factors that
contribute to the variation in and around empirical scaling relations for organ-
isms in different phylogenetic lineages, functional groups and environments.
The conceptual framework of MTE presumably applies to all organisms and
ecosystems. Marine and freshwater organisms and ecosystems are no exception.
Indeed, there is a rich tradition of empirical and theoretical work in biological
oceanography and limnology that relates the structure, function and biotic
composition of these systems to the body sizes of the organisms present and
the temperatures at which they are operating. We have presented just a few
examples to show more explicitly and quantitatively how the developing MTE
can be applied. Many of the contributions to this symposium volume present
additional examples.
But all these studies togetherprovide only a limited sample ofthe kinds ofwork
that can potentially be done, and the breadth and depth of understanding that
they can potentially contribute. Through fisheries, pollution, climate change and
other impacts, humans are transforming marine and freshwater ecosystems
faster than they can be studied in detail. More data are available for some systems,
such as temperate lakes and streams and the surface waters of temperate oceans,
than for others, such as tropical lakes and streams and the abyssal depths of the
oceans. The metabolic theory of ecology provides a general, quantitative concep-
tual framework, grounded in accepted first principles of biology, physics and
chemistry, not only for understanding the basic ecology of aquatic ecosystems,
but also for applying this knowledge to conservation, management and policy.References
Ackerman, J. L., Bellwood, D. R. & Brown, J. H.
(2004). The contribution of small indivi-
duals to density-body size relationships:
examination of energetic equivalence in
reef fishes.Oecologia, 138 , 568–571.
Allen, A. P., Brown, J.H. & Gillooly, J. F. (2002).
Global biodiversity, biochemical kinetics,
and the energetic-equivalence rule.Science,
297 , 1545–1548.
Allen, A.P., Gillooly, J.F. & Brown, J.H. (2005).
Linking the global carbon cycle to individual
metabolism.Functional Ecology, 19 , 202–213.
Belgrano, A., Allen, A.P., Enquist, B.J. & Gillooly,
J. F. (2002). Allometric scaling of maximum
population density: a common rule for
marine phytoplankton and terrestrial
plants.Ecology Letters, 5 , 611–613.
Brooks, J.L. & Dodson, S.I. (1965). Predation,
body size and composition of plankton.
Science, 150 , 28–35.
Brown, J.H. & Gillooly, J. F. (2003). Ecological
food webs: high-quality data facilitate
theoretical unification.Proceedings of the
National Academy of Sciences, 100 , 1467–1468.
Brown, J.H., Gillooly, J.F., Allen, A.P.,
Savage, V.M. & West, G. B. (2004). Towards
a metabolic theory of ecology.Ecology,
85 , 1771–1789.
Calder, W. A. (1984).Size, Function, and Life History.
Cambridge, MA: Harvard University Press.THE METABOLIC THEORY OF ECOLOGY 13