Figure 6.2Detrended correspondence analysis ordination biplot of the diets of
macroinvertebrate predators within Broadstone Stream (redrawn after Woodward &
Hildrew,2002b), showing a clear effect of body size along the first axis and the influence
of microhabitat use along the second axis. Predator species scores are labelled in bold
italics as initials, denoting genus (in decreasing order of mean body mass:Cordulegaster
boltonii–C;Sialis fuliginosa–S;Plectrocnemia conspersa–P;Macropelopia nebulosa–M;
Trissopelopia longimana–T;Zavrelimyia barbatipes–Z), followed by numbers, denoting size-
classes within species (low numbers representing the smallest size class). Prey taxa are
labelled as in Appendix 2 of Woodward & Hildrew (2002b). The arrows linking the seven
size classes of the top predatorCordulegaster(C1–C7) depict the ontogenetic shifts in diet
from the smallest to the largest individuals of this species. The smallest and largest ‘prey’
species found in the guts of the predators are denoted with stars and highlighted inbold
type(cyclopoid copepods andC. boltonii, respectively). The solid line drawn parallel to the
x-axis separates the epibenthic ambush predators from the interstitial searching
predators, barring two exceptions (C5andM3).
BODY SIZE AND PREDATORY INTERACTIONS IN FRESHWATERS 103