Because impacted streams usually do

Because impacted streams usually do not have riparian vegetation, they have lower levels of dissolved oxygen due to higher light entrance, higher daily variation indissolved oxygen concentrations, and higher levels of organic matter (in case of presence of cattle) (Suriano et al., 2011). For the refuge building trait—i.e., trait states representing if species construct mobile shelters of sand, twigs, or leaves (mainly trichopterans and chironomids larvae)—and the trophic group trait, we reasoned that impacted streams would have species with no refuge building and mostly detritivorous species, whereas pristine streams with preserved riparian vegetation would have all states of both traits (including taxa that construct shelters of leaves and twigs and leaf shredder species) (Cummins et al.,
2005). Thus, because the results of functional diversity metrics should be a response of traits to the environment, we expected that anthropic impacts would diminish the values of functional diversity metrics.