FORUM: Ecological networks: the missing links in biomonitoring science

Abstract

Monitoring anthropogenic impacts is essential for managing and conserving ecosystems, yet current biomonitoring approaches lack the tools required to deal with the effects of stressors on species and their interactions in complex natural systems.Ecological networks (trophic or mutualistic) can offer new insights into ecosystem degradation, adding value to current taxonomically constrained schemes. We highlight some examples to show how new network approaches can be used to interpret ecological responses.Synthesis and applications. Augmenting routine biomonitoring data with interaction data derived from the literature, complemented with ground-truthed data from direct observations where feasible, allows us to begin to characterise large numbers of ecological networks across environmental gradients. This process can be accelerated by adopting emerging technologies and novel analytical approaches, enabling biomonitoring to move beyond simple pass/fail schemes and to address the many ecological responses that can only be understood from a network-based perspective.

Keywords: anthropogenic stress; climate change; conservation; food web; global warming; mutualism; pollination.

Figure 1

Effects of habitat modification on food web metrics (mean ± SEM) While some of the more traditional network metrics show no change across the gradient (connectance, linkage density) others, such as interaction evenness and node vulnerability, are sensitive to environmental degradation. Letters above individual means indicate significant differences among habitat types for that particular metric. Letters in common or no letters indicate no significant difference. Adapted from Tylianakis, Tscharntke & Lewis (2007).

Figure 2

Broadstone stream food webs plotted as species abundance versus body mass data, with links between nodes representing trophic interactions. The abundance of invertebrates declines despite improving environmental conditions, as top‐down effects intensify. Redrawn from Layer et al. (2011).

Figure 3

A conceptual diagram of how a networks based approach to biomonitoring can be incorporated into and work alongside traditional biomonitoring protocols through the use of Next‐Generation Sequencing technologies and a data base of ecological interactions.