Future scenarios of biological invasions threaten endemism in a neotropical basin

Abstract

Globalization and climate change are accelerating the introduction of non-native fish species, posing a threat to global biodiversity. However, monitoring of these species remains neglected in many Neotropical regions, and studies applying tools to detect and track invasions, especially at early stages, are still scarce. In the Iguaçu River Basin, southern Brazil, the uncontrolled introduction of non-native species has posed a risk to local endemism. Given the threat of negative impacts on regional biodiversity, this study aimed to assess the invasive potential and to model current and future (2040–2100) invasion scenarios for five non-native species in the Iguaçu River Basin. The Aquatic Species Invasiveness Screening Kit (AS-ISK) was used to determine the invasive potential of each of the five species analyzed, and ecological niche modeling was applied to evaluate the current and future environmental suitability of the target species. All five species assessed exhibited high potential invasion risk in the region. Current and future environmental suitability varied among species across sections of the basin and among the future periods analyzed; however, all of these species require early and urgent monitoring. In particular, Cichla kelberi and Micropterus salmoides (already recorded in the basin), as well as Plagioscion squamosissimus (not yet recorded), showed a high probability of near-term invasion, indicating the need for targeted management actions. Therefore, decision-makers should implement strict public policies to monitor and contain the spread of these species in the Iguaçu River Basin, ensuring the preservation of its endemic ichthyofaunal biodiversity and anticipating a potential environmental collapse and threats to the region’s unique endemism.