Ensamblaje de macroinvertebrados acuáticos en dos arroyos del piedemonte llanero en la ecoreserva ASA, Acacias - Meta

Abstract

Aquatic macroinvertebrates (AMI) are one of the most studied biological groups in Colombia, but their knowledge remains limited in the Orinoquia and the Llanero foothills, in aspects of diversity, ecology and biology. This study focused on the Bijao and NN channels of the ASA La Guarupaya Ecoreserve, in Acacias, Meta. The objective was to determine the composition and spatiotemporal structure of AMI and their relationship with environmental variables. A monthly sampling with a multihabitat approach was carried out and environmental variables were measured from December to May. 11,746 individuals, 70 families and 146 genera were collected. The most abundant families were Chironomidae (Diptera); Leptophlebiidae, Baetidae and Leptohyphidae (Ephemeroptera); Elmidae (Coleoptera); and Polycentropodidae and Hydropsychidae (Trichoptera). Regarding the space-time structure, a differentiated MIA assembly was found between streams, with the months of transition towards high waters being where the greatest abundance and richness of taxa was presented, with dissolved oxygen and flow as the environmental variables with the greatest influence on the AMI. The greater availability and types of microhabitats of the Bijao channel compared to the NN channel allowed for a greater abundance and richness of taxa in one channel compared to the other. This supply of microhabitats increased during the transition periods towards high waters, mainly in the stream. NN, while in the periods of receding water and low water, brought with them a reduction in flow, and, therefore, a lower availability of microhabitats, but also lower values, for example, in dissolved oxygen. These results highlight the diversity of AMI in the Llanero foothills and the heterogeneity of the aquatic ecosystems in the region, while the ASA La Guarupaya Eco-Reserve is established as an important area for the conservation of aquatic ecosystems and their fauna, in an area impacted by anthropic activities such as the municipality of Acacias and the middle basin of the Orotoy River.