The impacts of alien species on river bioassessment

The impact of alien taxa on river ecosystem health is uncertain, but their presence continues to rise. The paper with title “The impacts of alien species on river bioassessment” presents the results of work carried out by a global collaboration of researchers in the field, which examined the inclusion of alien taxa in bioindicators for river bioassessment, their effect on native species richness and abundance, and whether their inclusion improved sensitivity to river degradation. According to the paper, across 17 countries, fish had the highest number of alien species (1726), followed by macrophytes (925), macroinvertebrates (556), and diatoms (7). Alien species are often only distinguished in some fish and macrophyte indices. Analysis of data from eight databases indicated that alien taxa abundance correlates with various stressors leading to river degradation and significantly affects native community composition. When accounting for alien species, there was a strong negative correlation between fish index values and alien richness and abundance. Recommendations include incorporating specific metrics for alien species in quality indices, investigating small organisms, eliminating invaded sites as reference points, excluding aliens from total richness calculations, identifying species in biomonitoring programs, avoiding protection legislation for alien species, and promoting behaviors to prevent alien invasions.

Author(s): University of Coimbra

Resources: “The impacts of alien species on river bioassessment” (2025), J. F. Maria, P. S. Janine, M. H. Robert, C. A. Francisca, Journal of Environmental Management, https://www.sciencedirect.com/science/article/pii/S0301479724038611?via%3Dihub, (Accessed on 13.01.2025)