Abiotic variables (turbidity in (a) and temperature in (b)) followed by biotic ones (<i>I_H(M)</i> for OMNI in (a) and TERR in (b)).

<p>To help visual comparability, values have been transformed in such a way that the minimum and the maximum value be equal to 0 and 1, respectively. The <i>x</i> axis is the series of study sites.</p

The <i>I_H(V)</i> value for four selected trophic groups at each site.

<p>The top-down effects of fish on the dynamical variability of other groups in increasing in the more human-influenced site.</p

The food web of the pristine river (site 1), size of nodes is proportional to six measures of importance: <i>D</i> (a), <i>nBC</i> (b), <i>K</i> (c), <i>TI³</i> (d), <i>I_H(V)</i> (e) and <i>K_H(V)</i> (f).

<p>Network drawn by COSBILAB Graph <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0040280#pone.0040280-Valentini1" target="_blank">[17]</a>.</p

Importance ranks of trophic groups in the food web of the pristine river (site 1).

<p>Ranking is based on topological (<i>D</i>, <i>nBC</i>, <i>K</i>, <i>TI³</i>) and dynamical (<i>I_H(M)</i>, <i>I_H(V)</i>) measures, as well as keystone indices considering also population size (<i>K_H(M)</i>, <i>K_H(V)</i>). The <i>I_H(M)</i> and <i>I_H(V)</i> indices for all groups in each of the six sites are given in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0040280#pone.0040280.s005" target="_blank">Appendix S5</a>.</p