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CHAPTER FOUR

Relationship between biomass turnover

and body size for stream communities

ALEXANDER D.HURYN

University of Alabama

ARTHUR C.BENKE

University of Alabama

Introduction
A crucial requirement for the analysis of energy flow through freshwater food
webs is the accurate and precise estimation of secondary production (Benke
et al., 1988). Therateof production (or biomass-turnover rate) is often expressed
as either annual production-to-biomass ratios (annual P/B) or daily biomass-
growth rates (g, AppendixI). Invertebrate production and annual P/Bs have now
been estimated on a taxon-specific basis for a relatively wide range of freshwater
habitats, streams and rivers in particular, and often this has been done within
a community context (see reviews by Benke, 1993 and Huryn & Wallace, 2000 ).
The relationships between body size and either daily or annual P/B for fresh-
water invertebrates have been assessed using empirical approaches (Banse &
Mosher, 1980 ; Plante & Downing, 1989 ; Morin & Bourassa, 1992 ; Benke, 1993 ;
Morin & Dumont, 1994 ). The results of such studies provide strong evidence that
annual P/B is negatively related to body size (AppendixI; Fig.4.10). However,
recent efforts showing remarkably high P/Bs for some benthic macroinverte-
brates in both warm-water (e.g. Benke, 1998 ; reviewed by Huryn & Wallace,
2000 ) and cool-water streams (e.g. Nolte & Hoffman, 1992 ) suggest that the
results of these early studies – Banse and Mosher’s ( 1980 ) still widely cited
analysis, for example – greatly underestimate biomass turnover. Furthermore,
because they are based on meta-analytical approaches incorporating compar-
ison of populations taken from many different communities, these earlier
studies do not allow the analysis of factors constraining patterns of P/B as a
function of the body size of individual taxawithinsingle communities.
The allometric relationship between body size and bioenergetic variables has
captured the interest of ecologists for some time (reviewed by Peters, 1983 ;
Schmidt-Nielsen, 1984 ; Glazier, 2006 ). Recent studies of the role of metabolic
constraints as determinants of the relationship between body size and produc-
tion have advanced earlier efforts by producing a conceptual framework that
explicitly links metabolic theory with ecological theory (Brownet al., 2004;

Body Size: The Structure and Function of Aquatic Ecosystems, eds. Alan G. Hildrew, David G. Raffaelli and Ronni
Edmonds-Brown. Published by Cambridge University Press.#British Ecological Society 2007.