Macroinvertebrate functional feeding group structure along an impacted tropical river : the Portoviejo River (Ecuador)

Performing biological assessments of freshwater systems is crucial in most tropical rivers as the lack of in-depth knowledge about functional diversity inhibits the design of appropriate water management and restoration plans. Therefore, in this paper, we investigated the presence and evolution of the functional diversity of the macroinvertebrate community along a tropical river. More specifically, 31 locations were sampled in the Portoviejo River (Ecuador) and identified macroinvertebrates were assigned to one of the following functional feeding groups (FFGs): shredders, collector-gatherers, collector-filterers, scraper-grazers and predators. Results show that high fluctuations and relatively low similarity in functional feeding group composition occurred among closely located sites, suggesting the presence of local disturbances. Locations close to the effluent of a wastewater treatment plant show an extreme dominance of scraper-grazers, suggesting elevated nutrient input and algae growth. Further downstream, the interaction of upstream disturbances and local land use influenced the community composition. These interactions and the confirmation of the importance of land use on aquatic communities underline the fact that management should include both taxonomic and functional diversity