emphasizes the distinctness for multifractality of the BSDs in all streams (Fig.8.6a).
This result strongly contrasts to spectra, which would collapse into a narrow range
of or even into a single value for a strictly monofractal, homogeneous size
distribution with a single scaling exponent. In the three streams, the multifractal
spectra were characterized by similar entropy dimensions, (1)¼D 1 with values
close to 1, which predicts that the irregularities of the species-frequency distribu-
tion are even across body sizes (Figs.8.4& 8.6a;Table8.3).
The fraction of small-sized particles from interstitial sediments may serve as a
potential food and habitat source for the benthic communities. The particle-size
distribution displayed a decline in the mean number of particles with increasing
particle size (inset Fig.8.4). Scaling irregularities increased with particle size and
were particularly pronounced in the SB (inset Fig.8.4). The interstitial particleMean number of species,<S^ >(λ)^ m–2SB01020304050LL0510152025MYMean body-length, λ (mm)0510152025n = 332n = 2600246810n = 448Particles,<P>^ (λ)^ml–1^Particles,<P>^ (λ)^ml–1Particles,<P>^ (λ)^ml–11001011021031041051061070 5 10 15 20 25 30031 2031 2031 210010110210310410510610710010110210310410510610702468100246810Figure 8.4Species- and
particle-size frequency
distribution in three stream
ecosystems (Seebach (SB),
Llwch (LL) and Mynach (MY)).
Mean number of species per
1m^2 given over 300 size-
classes in increments of
100 mm for the total size
range30 mm. The figure
insets show the most
abundant species over 300
size classes in increments of
10 mm for body sizes3 mm.
Mean particle density per
1 ml over 600 size classes in
increments of 5mm is shown
superimposed in the inset as
open circles (SB), triangles
(LL) and squares (MY).nis the
number of species in each
stream community.156 P.E. SCHMID AND J. M. SCHMID-ARAYA