Laguna de Olomega is a tropical lake in southeastern El Salvador that supports a rich ecosystem and is deeply connected to nearby communities. However, this lake is under serious threat from pollution, invasive species like tilapia and water buffalo, and untreated wastewater. These pressures are harming both aquatic wildlife and the surrounding land-based species. Yet, little is known about which species still live in and around the lake, making it difficult to conserve them.

To fill this gap, we used a technique called environmental DNA (eDNA) to detect and inventory which animals are present in the lake without needing to see or capture them. By collecting and analyzing small traces of DNA from lake water and sediment, we are able to identify species of fish, amphibians, reptiles, mammals, and invertebrates such as insects and mollusks. We used three different DNA markers to get a full picture of the lake’s biodiversity.

Our results will help identify species that indicate ecosystem health or stress, and guide conservation strategies rooted in both science and community knowledge. By involving local people in this process, we aim to build long-term solutions that improve biodiversity monitoring, empower communities, and support local decision-making for sustainable lake management.