Influence of Fish Farming on the Spatial Patterns and Biological Traits of River Invertebrates in an Appenine Stream System (Italy)

In applied river ecology it is implicitly assumed that community structure is a surrogate for functional properties. To test this hypothesis, 26 sites were sampled for macroinvertebrates in a Central Italian stream system impacted by 13 trout farms (1 upstream and 1 downstream site per facility). We used a fuzzy-coding approach of biological traits combined with species distribution analysis. Trout farm locally impacted the structure of macroinvertebrate communities, but serial disturbances at the stream system scale did not affect the overall regional diversity pattern. Impacted sites had species with large body size, which fed upon microorganisms and fine detritus, and which showed asexual reproduction. Least impact sites hosted small-sized invertebrates showing sexual reproduction, and feeding upon plant material and/or algae.