Composition and structure of macroinvertebrates in an Amazonian lagoon (Guaviare, Colombia)

Introduction. Benthic macroinvertebrates are widely used organisms for assessing the ecological health of fres-hwater ecosystems, as they respond to variations in environmental conditions. Thus, their composition and struc-ture are key indicators in lacustrine systems infl uenced by the flood pulse. Objective. This study analyzed the composition and structure of aquatic macroinvertebrates in a permanent lagoon located in the village of Gaviotas, municipality of Calamar, Guaviare, as part of a wetland system subject to hydroperiodic variations. Materials and methods. Sampling was carried out in August and October 2018 (high-precipitation period) and February 2019 (low-precipitation period) in two zones: the littoral zone with abundant macrophytes and the Aquatic-Te-rrestrial Transition Zone (ATTZ). Individuals were collected with a D-frame net, preserved, and identifi ed using specialized taxonomic keys. Community structure was evaluated using Simpson’s dominance index, Shannon’s diversity index, Margalef’s richness index, and Morisita’s similarity index. Results. A total of 1,587 individuals were collected, belonging to 5 classes, 13 orders, 40 families, and 76 genera or morphogenera. The most abundant families were Chironomidae, Libellulidae, Hydrophilidae, Dytiscidae, Baetidae, and Glossiphoniidae. Diversity was higher in the ATTZ during the dry season. Conclusions. The composition and structure of macroinvertebrates were infl uenced by hydroperiods, changes in macrophyte cover, and substrate variations. The lagoon exhibits a high diversity of aquatic macroinvertebrates, determined by the dynamic characteristics of its habitat, such as the fl ood pulse and the presence of macrophytes. These results highlight the importance of interactions between the physical habitat and biota in tropical wetland systems.

Keywords: Amazonia, hydroperiods, fl ood pulse, macrophytes