Multiple anthropogenic sources, such as contamination, habitat degradation, eutrophication, and, more recently, fishing, have steadily been impacting marine ecosystems for at least the past two centuries, generating probably irreversible structural and functional changes (Estes et al., 2011; Lotze & Milewski, 2004). In particular, increasing fishing pressure during the past 50 years and habitat degradation have had a wide range of impacts on ecosystems worldwide, which are reflected in changes in abundance, spatial distribution, productivity, and structure of exploited communities (Blaber et al., 2000; Hall, 1999; Jackson et al., 2001; Lotze et al., 2006; Myers & Worm, 2005). These impacts on community structure and function have been widely documented and quantified in many marine ecosystems (Haedrich & Barnes, 1997; Jennings & Kaiser, 1998; Pauly et al., 1998; Sala et al., 2004; Worm et al., 2006; Yemane et al., 2005).

Some authors have suggested that, although changes in species composition are an important indicator to identify perturbed ecosystems, a holistic knowledge allowing identification of structural and functional effects could emerge from the study of communities as networks interconnected by trophic interactions (Bascompte et al., 2005; Dunne et al., 2002). Owing to the relatively stable characteristics of trophic networks, these interactions can provide information on species relationships within a community and how human activities could be degrading ecosystems (Dell et al., 2005).