Spatial variability and trophic structure of aquatic macroinvertebrate communities in the semi-arid Quilca-Chili basin, Peru

Introduction: The trophic structure of macroinvertebrate communities is of particular interest for understanding the functioning of the river ecosystems. Objective: To determine the community structure and functional feeding groups of aquatic macroinvertebrates in the Quilca-Chili basin. Methods: Two sampling campaigns were conducted at 26 stations, distributed across six sectors, from June to October 2022. The community structure was analyzed based on basic ecological parameters, including taxonomic richness, dominance, evenness, and diversity. Spatial variability was assessed through a similarity percentage analysis and non-metric multidimensional scaling using the Bray-Curtis distance index. The relationship with physicochemical variables was determined through canonical correlation analysis. Results: A total of 51 families were identified and assigned to functional feeding groups: predator, shredder, collector-gatherer, scraper, and filterer. The highest and lowest diversity was observed in the Sihuas sector and the Chili and Lluta sectors, respectively. Differences in community structure indices were found between the six sectors of the basin. The most abundant functional feeding groups were scrapers, while shredders and predators were the least abundant. Conclusion: The spatial distribution reflects the complexity and variability among physicochemical parameters and functional feeding groups in this basin.