Assembly of aquatic macroinvertebrates in lotic ecosystems of Reserva natural el Caduceo, San Martin-Meta, Colombia

Abstract

Aquatic macroinvertebrates are characterized by their high variability and adaptability to environmental changes, allowing them to play a fundamental role in the functioning of aquatic ecosystems and making them key bioindicators of water quality. This study aimed to analyze the relationship between physicochemical variables of water bodies and the structure of macroinvertebrate communities in the El Caduceo Natural Reserve, located in the Colombian Orinoquía piedmont. Quantitative and qualitative sampling was conducted at two sites: a stream and the sub-basin of the Camoa River. Physicochemical variables, including pH, temperature, total dissolved solids, and electrical conductivity, were measured, and D-net, kick net, and Surber sampler were used for organism collection. Taxonomic identification was performed to family and genus levels. Water quality was assessed using the BMWP/Col index, and diversity and evenness metrics were estimated. Results showed that the stream exhibited higher richness, diversity, and evenness, whereas the Camoa River presented a simplified community dominated by tolerant taxa such as Trichoptera. BMWP/Col values indicated moderately polluted conditions in the stream and highly polluted conditions in the river. These findings suggest that dissolved oxygen directly influences community structure and diversity, highlighting the importance of macroinvertebrates as effective tools for environmental monitoring.