AIMS & CONTEXT:
Evaluations of aquatic biodiversity and of the river ecological status are usually regarded in separated compartments for the diverse co-occurring biological groups. For instance, the classification offered by the EU-Water Framework Directive (2000/60/EC) is based in the biological quality element (e.g. microalgae, benthic invertebrates) that was lowest ranked (one-out-all-out approach), and riparian vegetation is considered a geomorphological component. It is our purpose to incorporate ecological realism to assessments of fluvial ecological quality by a process-based understanding of the overall fluvial ecosystem.
RESOURCES AND METHODS:
Feio et al. (2017) found for Portuguese river benchmarks (minimally disturbed locations) a set of predictable functional associations between aquatic organisms and riparian vegetation. For each taxa recorded of each biological group (Activity 2), we will assign trait categories (trophic group for macroinvertebrates, form/type of attachment for diatoms, and growth-forms for macrophytes), and derive functional guilds for riparian vegetation (as in Aguiar et al., 2017 and Bejarano et al., 2017). In this sense, a riparian guild is a group of co-occurring species that share similar traits (e.g. leaf thickness, leaf anatomy, root type) that suit them to interact with aquatic environment and biota. To assess if regulation determines changes in abundance of associations and guilds, we first test whether each association/guild responded to the hydrological regime (free-flowing vs. regulated) and other stressors (e.g. land use). For this purpose, we will fit Generalized Mixed-Models (GLMM) using stressor variables as the fixed effect. Then, we will model the likelihood of finding guilds and associations of aquatic and riparian biota in a particular site by running Stepwise Multiple Linear Regressions (MLR) or, in alternative, Generalized Linear Models (GLM). This analysis will enable us to predict the probability of presence of each association/riparian guild as a function of a combination of the most significant pressure variables (i.e., in explaining the guild’s and associations presence/absence pattern) selected by a step-wise forward procedure.