Abstract

Links between ecosystem collapse and biological invasions have been scarcely documented with empirical field measurements. In Chile the recent collapse of Aculeo lake, which was the largest natural freshwater body of the Central zone of Chile, produced a serious socio-environmental crisis in the local population. Here, we aim to report the concerning densities of the highly invasive Bagrada hilaris in this recently collapsed ecosystem. Densities of B. hilaris in plots combined with mapping of the area covered by infested plants allowed us to estimate the size of the B. hilaris population. Densities of B. hilaris in the dried lake reached 628.88 +/- 95.28 ind/m(2) and the infested area amounted to 310 ha, representing 26% of the total lake area. The population of B. hilaris in the dried Aculeo Lake reached 1948.9 +/- 295.3 million individuals. Here we highlight the need for control actions to avoid a potential invasion over important nearby crops and protected areas, and the link between freshwater ecosystem collapse with the rapid colonization of invasive species.