Procambarus clarkii in Andean Waters: Ecological impacts and mitigation efforts

In 2013, the invasive crayfish species Procambarus clarkii was introduced into the high Andean lake of Yahuarcocha in Ecuador. By 2018, the population had increased significantly, coinciding with the last recorded presence of submerged macrophytes. By 2020, the abundance of P. clarkii had declined, with only a few individuals detected in traps or after several days of monitoring in areas adjacent to the lake. P. clarkii is considered a major factor driving the lake into a hypereutrophic state, exacerbated by anthropogenic influences such as sewage and influent pollution. This crayfish species is also associated with changes in the composition of the local macroinvertebrate and fish communities. Since 2019, various efforts have been made to improve the water quality of the lake. These efforts include the control and monitoring of influents and effluents, the use of ultrasound technology, eDNA monitoring and the reintroduction of aquatic plants. Initially, these measures resulted in a resurgence of submerged macrophytes in 2021. However, in 2023 the regrowth of the P. clarkii population reduced the submerged macrophytes again. Currently the species is present in twelve water bodies in the Ecuadorian highlands.