L. Peters et al.
Journal of the North American Benthological Society 26(1): 78–91 (2007)
Spatial variation of grazer effects on epilithic meiofauna and algae
L. Peters 1,3,
H. Hillebrand 2, and W. Traunspurger
1Limnological Institute, University of Konstanz, Germany
2University of Cologne, Institute for Botany, Germany
3University Bielefeld, Animal Ecology, Germany
Periphyton is a key component of shallow littoral zones of lakes and streams because it is an important
source of primary production and a food resource for herbivores. Meiofauna are abundant in periphyton,
but macroinvertebrate grazer (macrograzers) effects on periphytic meiofauna have not been studied so far.
We used a spatially structured field experiment (hierarchical nested design consisting of 3 subsites at
each of 3 sites) in Lake Erken (Sweden) to investigate the effect of macrograzers on epilithic meiofauna and
algae in periphyton by controlling macrograzer access to littoral periphyton communities. Overall, we found a
strong negative effect of macrograzer presence on algal biomass and some evidence for negative macrograzer effects
on meiofaunal abundance and community composition. The impact of macrograzers on both algae and meiofauna were
highly variable between sites and subsites. The largest spatial differences were for macrograzer effects on
meiofaunal abundance and composition. We also investigated the ability of macrograzers to reduce spatial
heterogeneity of periphyton biomass, but the presence of macrograzers did not alter the variation in algal biomass
and associated meiofauna among replicates. We conclude that strong local variability in algal biomass and meiofauna
abundance exists between neighboring sites even in the presence of strong overall macrograzer effects. This local
variability could be based on factors known to cause spatial heterogeneity such as hydrodynamics, nutrients,
substrate characteristics (size, texture, exposure), or biotic interactions.