Trophic structure and functional feeding groups of macroinvertebrates in a section of the Gallinazo tropical stream

Abstract

Aquatic macroinvertebrates play crucial roles in ecosystem processes such as grazing, decomposition, and mineralization. Classifying these organisms into functional feeding groups (FFGs) enables a more comprehensive understanding of energy and matter flow through trait-based approaches, complementing traditional taxonomic methods. The study analyzed the trophic structure and FFG variation of aquatic macroinvertebrates in a section of a tropical stream, located in the municipality of Aguachica, Colombia. Sampling was carried out during the rainy season in May and the dry season in July 2024, during which the composition and abundance of macroinvertebrate feeding groups were analyzed. Physical and chemical parameters were measured both in situ and ex situ at strategically selected stations based on accessibility and location. Macroinvertebrates were collected using Surber and D-type nets and identified to the family level. They were then assigned to functional feeding groups. Ecological indices and multivariate statistical analyses were applied to evaluate ecosystem attributes. Results revealed seasonal variations in water parameters, including lower dissolved oxygen and higher chemical oxygen demand during the dry season, suggesting potential organic pollution. Macroinvertebrate richness was higher during the dry season, with Caenis sp. and Tanypodinae sp. being dominant, while Drepanotrema sp. and Physa sp. were more abundant during the rainy season, reflecting eutrophic conditions. The P/R index indicated heterotrophic dominance, and low CPOM/FPOM ratios pointed to limited riparian cover. These findings underscore the importance of implementing conservation strategies to mitigate anthropogenic pressures and preserve the ecological integrity of freshwater ecosystems.